Chlamydia pneumoniae can infect the central nervous system via the olfactory and trigeminal nerves and contributes to Alzheimer’s disease risk

May combine two claims.

Hspa4 maintained the disaggregating property of misfolded proteins, thereby preventing further damage and inducing tissue integrity.

“Amongst the heat shock proteins, we found Hspa4 to be upregulated which ensured that it maintained the disaggregating property of any misfolded proteins, thereby, preventing further damage and inducing tissue integrity89.”

• cites [89] Koopman, M. B. & Rüdiger, S. G. Alzheimer cells on their way to derailment show selective changes in protein quality control network. Front. Mol. Biosci. 7, 25 (2020). sourceDisputed

  The Results section, “HSP70 Efflux Derails Toward Autophagy” (page unavailable), identifies HSPA4 as contributing to Hsp70-mediated disaggregation but explicitly says its levels remained unaffected in Alzheimer’s brains—not upregulated. It does not report that HSPA4 prevented further damage or improved tissue integrity. (LLM, conf=0.88)

  Checked by a reasoning model — may be wrong.

  Experimental — accuracy not yet measured

May combine two claims.

C. pneumoniae DNA, antigen and/or live bacteria have been detected in the brain of inoculated mice, which resulted in Aβ deposition or altered appearance of Aβ deposits.

“C. pneumoniae DNA, antigen and/or live bacteria have been detected in the brain of inoculated mice15–18, which resulted in Aβ deposition16,17 or altered appearance of Aβ deposits18.”

• cites [15] Little, C. S. et al. Age alterations in extent and severity of experimental in infection with Chlamydophila pneumoniae in BALB/c mice. Infect. Immun. 73, 1723–1734. https://doi.org/10.1128/IAI.73.3.1723-1734.2005 (2005). sourcePartly supported

  The Results report C. pneumoniae antigen and viable bacteria in the brains of inoculated mice. The Discussion reports Aβ deposits in infected mice from previous work, but this study did not assess Aβ deposition and our copy does not report an altered appearance of Aβ deposits. (LLM, conf=0.86)

  Experimental — accuracy not yet measured
• cites [16] Little, C. S., Hammond, C. J., MacIntyre, A., Balin, B. J. & Appelt, D. M. Chlamydia pneumoniae induces alzheimer’s-like amyloid plaques in brains of BALB/c mice. Neurobiol. Aging 25, 419–429. https://doi.org/10.1016/S0197-4580(03)00127-1 (2004). sourceNot checked — no full text of the source
• cites [17] Little, C. S. et al. Detection of bacterial antigens and Alzheimer’s-like pathology in the central nervous system of BALB/c mice following intranasal infection with a laboratory isolate of Chlamydia pneumoniae. Front. Aging Neurosci. 6, 304. https://doi.org/10.3389/fnagi.2014.00304 (2014). sourceSupported
• cites [18] van Boelen, E. et al. Detection of amyloid beta aggregates in the brain of BALB/c mice after Chlamydia pneumoniae infection. Acta Neuropathol. 114, 255–261. https://doi.org/10.1007/s00401-007-0252-3 (2007). sourcePartly supported

  The Discussion reports C. pneumoniae DNA in the olfactory bulbs of infected mice one week after inoculation. But it reports nearly identical Aβ immunoreactivity in infected, mock-infected, and uninoculated BALB/c mice, suggesting that the deposits did not directly result from infection. The morphological differences described in the Results are between BALB/c and transgenic mice, not between infected and uninfected BALB/c mice. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

May combine two claims.

C. pneumoniae can infect lung macrophages, which migrate through the mucosal barrier and enter the blood; the bacteria can disseminate to vasculature by surviving intracellularly in blood monocytes, which can then cross the blood-brain barrier (BBB).

“C. pneumoniae can infect lung macrophages, which migrate through the mucosal barrier and enter the blood; the bacteria can disseminate to vasculature by surviving intracellularly in blood monocytes, which can then cross the blood–brain barrier (BBB)19.”

• cites [19] Gieffers, J. et al. Phagocytes transmit Chlamydia pneumoniae from the lungs to the vasculature. Eur. Respir. J. 23, 506–510. https://doi.org/10.1183/09031936.04.00093304 (2004). sourcePartly supported

  Split into 2 atoms — 1 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing).

Other studies have failed to detect higher levels of C. pneumoniae in post-mortem brains from patients with late-onset dementia.

“In contrast, however, other studies have failed to detect higher levels of C. pneumoniae in post-mortem brains from patients with late-onset dementia14, although the analytical methods have varied between studies7.”

• cites [14] Ring, R. H. & Lyons, J. M. Failure to detect Chlamydia pneumoniae in the late-onset Alzheimer’s brain. J. Clin. Microbiol. 38, 2591–2594 (2000). sourceSupported

May combine two claims.

Aβ is an antimicrobial peptide, released by neural cells in response to infectious agents.

“It is now well known that Aβ is an antimicrobial peptide, released by neural cells in response to infectious agents12,13, so it is not surprising that the presence of bacteria in the brain can result in Aβ deposition reviewed in8.”

• cites [12] Soscia, S. J. et al. The Alzheimer’s disease-associated amyloid beta-protein is an antimicrobial peptide. PLoS One 5, e9505. https://doi.org/10.1371/journal.pone.0009505 (2010). sourcePartly supported

  The Abstract (Methodology/Principal Findings; page unavailable) reports Aβ’s antimicrobial activity, and the Discussion calls it an antimicrobial peptide. But the Discussion presents increased Aβ generation in response to infection as a possibility, not an established finding, and does not show that neural cells release Aβ in response to infectious agents. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [13] Kumar, D. K. et al. Amyloid-beta peptide protects against microbial infection in mouse and worm models of Alzheimer’s disease. Sci. Transl. Med. 8, 340ra372. https://doi.org/10.1126/scitranslmed.aaf1059 (2016). sourcePartly supported

  The Introduction and Discussion describe Aβ’s antimicrobial activity, and the Results report that cultured human brain neuroglioma cells secrete Aβ. But the Discussion says the study’s models expressed Aβ constitutively and could not test whether infection normally increases its production; it cites other investigators’ findings only as suggesting that Aβ may be inducible. The source therefore does not establish that neural cells release Aβ in response to infectious agents. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

May combine two claims.

The mice used in these studies were wild-type mice and not mouse models of Alzheimer's disease, suggesting that C. pneumoniae can contribute to the neuropathologies associated with late-onset dementia.

“Importantly, the mice used in these studies were wild-type mice and not mouse models of Alzheimer’s disease, suggesting that C. pneumoniae can contribute to the neuropathologies associated with late-onset dementia.”

• cites [15] Little, C. S. et al. Age alterations in extent and severity of experimental in infection with Chlamydophila pneumoniae in BALB/c mice. Infect. Immun. 73, 1723–1734. https://doi.org/10.1128/IAI.73.3.1723-1734.2005 (2005). sourceSupported
• cites [16] Little, C. S., Hammond, C. J., MacIntyre, A., Balin, B. J. & Appelt, D. M. Chlamydia pneumoniae induces alzheimer’s-like amyloid plaques in brains of BALB/c mice. Neurobiol. Aging 25, 419–429. https://doi.org/10.1016/S0197-4580(03)00127-1 (2004). sourceNot checked — no full text of the source
• cites [17] Little, C. S. et al. Detection of bacterial antigens and Alzheimer’s-like pathology in the central nervous system of BALB/c mice following intranasal infection with a laboratory isolate of Chlamydia pneumoniae. Front. Aging Neurosci. 6, 304. https://doi.org/10.3389/fnagi.2014.00304 (2014). sourceSupported
• cites [18] van Boelen, E. et al. Detection of amyloid beta aggregates in the brain of BALB/c mice after Chlamydia pneumoniae infection. Acta Neuropathol. 114, 255–261. https://doi.org/10.1007/s00401-007-0252-3 (2007). sourcePartly supported

  The Discussion identifies the infected BALB/c mice as naïve, non-transgenic mice, supporting the wild-type part of the claim. But it reports similar Aβ immunoreactivity in infected and uninfected mice and concludes that the data do not unequivocally support infection-induced AD-like plaques. The proposed contribution to late-onset dementia remains a possibility, not a finding established by this study. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

May combine two claims.

Chlamydia infection can induce cellular stress that impacts protein folding, thus inducing UPR activation; it is also proposed to modulate the UPR to promote its survival and replication.

“Chlamydia infection can induce cellular stress that impacts protein folding, thus inducing UPR activation however it is also proposed to modulate the UPR to promote their survival and replication79.”

• cites [79] Smith, J. A. Regulation of cytokine production by the unfolded protein response; implications for infection and autoimmunity. Front. Immunol. https://doi.org/10.3389/fimmu.2018.00422 (2018). sourcePartly supported

  The 'Implications for Bacterial Infections' section (page not provided) reports that Chlamydia infection activates several ER-stress pathways, supporting the first part of the claim. It does not propose that Chlamydia modulates the UPR to promote its own survival or replication; the discussion of UPR-supported bacterial replication concerns Brucella. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

After approximately 72 h (in cell culture), the RBs transform into EBs, which are released by cell lysis and can infect new cells.

“After approximately 72 h (in cell culture), the RBs transform into EBs, which are released by cell lysis and can infect new cells (exit via extrusion of membrane-bound compartments can also occur39).”

• cites [36] Abdelrahman, Y. M. & Belland, R. J. The chlamydial developmental cycle. FEMS Microbiol. Rev. 29, 949–959. https://doi.org/10.1016/j.femsre.2005.03.002 (2005). sourceNot checked — no full text of the source
• cites [39] Zuck, M., Sherrid, A., Suchland, R., Ellis, T. & Hybiske, K. Conservation of extrusion as an exit mechanism for Chlamydia. Pathog. Dis. https://doi.org/10.1093/femspd/ftw093 (2016). sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing).

Several reports have described manifestations of ER stress in post-mortem brain samples from Alzheimer's disease patients.

“Several reports have described manifestations of ER stress in post-mortem brain samples from Alzheimer’s disease patients78.”

• cites [78] Hashimoto, S. & Saido, T. C. Critical review: Involvement of endoplasmic reticulum stress in the aetiology of Alzheimer’s disease. Open Biol. 8, 180024. https://doi.org/10.1098/rsob.180024 (2018). sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing).

Microglia activation reduces the accumulation of Aβ in the brain by increasing its phagocytosis, clearance, and degradation.

“Microglia activation reduces the accumulation of Aβ in the brain by increasing its phagocytosis, clearance, and degradation75.”

• cites [75] Ries, M. & Sastre, M. Mechanisms of Aβ clearance and degradation by glial cells. Front. Aging Neurosci. https://doi.org/10.3389/fnagi.2016.00160 (2016). sourcePartly supported

  The Phagocytosis section says microglia phagocytose Aβ, and the Conclusion says activated glial cells can promote its removal. But the Conclusion associates this protective function with a particular, alternatively activated microglial phenotype and also notes potentially detrimental effects of activation. The claim overstates this as an unqualified effect of microglial activation. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing).

The glia limitans layer between the peripheral nerves and brain, populated by astrocytes, constitutes a further immunological barrier against CNS infection.

“The glia limitans layer between the peripheral nerves and brain, populated by astrocytes, constitutes a further immunological barrier against CNS infection32,33.”

• cites [32] Nazareth, L. et al. Novel insights into the glia limitans of the olfactory nervous system. J. Comp. Neurol. 527, 1228–1244. https://doi.org/10.1002/cne.24618 (2019). sourceSupported
• cites [33] Jung, Y.-J. & Chung, W.-S. Phagocytic roles of glial cells in healthy and diseased brains. Biomol. Ther. (Seoul) 26, 350–357. https://doi.org/10.4062/biomolther.2017.133 (2018). sourceCould not verify

  The Introduction discusses astrocytes and glial phagocytosis as an innate immune defense, but does not describe the glia limitans or an astrocyte-populated barrier against CNS infection. Searches for the glia limitans and for a barrier between peripheral nerves and the brain found no passage addressing that claim in our copy. (LLM, conf=0.74)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing).

C. pneumoniae EBs can become internalized into host cells, including many phagocytes.

“C. pneumoniae EBs can become internalized into host cells, including many phagocytes1,37,38.”

• cites [1] Beagley, K. W., Huston, W. M., Hansbro, P. M. & Timms, P. Chlamydial infection of immune cells: Altered function and implications for disease. Crit. Rev. Immunol. 29, 275–305 (2009). sourceSupported
• cites [37] Armitage, C. W., O’Meara, C. P. & Beagley, K. W. Chlamydia pneumoniae and Chlamydia trachomatis infection differentially modulates human dendritic cell line (MUTZ) differentiation and activation. Scand. J. Immunol. 82, 48–54. https://doi.org/10.1111/sji.12295 (2015). sourcePartly supported

  The Results section reports internalized C. pneumoniae elementary bodies in iMUTZ dendritic cells, supporting uptake by a host phagocyte. The Introduction describes infection of several immune-cell types by Chlamydia species generally, but does not establish that C. pneumoniae EBs enter many types of phagocytes specifically. Page numbers are unavailable in our copy. (LLM, conf=0.82)

  Experimental — accuracy not yet measured
• cites [38] Herweg, J. A. & Rudel, T. Interaction of Chlamydiae with human macrophages. FEBS J. 283, 608–618. https://doi.org/10.1111/febs.13609 (2016). sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing).

Experimental injury to the olfactory neuroepithelium facilitates invasion of the olfactory nerve and bulb by certain bacteria.

“It has previously been shown that experimental injury to the olfactory neuroepithelium facilitates invasion of the olfactory nerve and bulb by certain bacteria27,28.”

• cites [27] Walkden, H. et al. Burkholderia pseudomallei invades the olfactory nerve and bulb after epithelial injury in mice and causes the formation of multinucleated giant glial cells in vitro. PLoS Negl. Trop. Dis. 14, e0008017. https://doi.org/10.1371/journal.pntd.0008017 (2020). sourceSupported
• cites [28] Herbert, R. P. et al. Cytokines and olfactory bulb microglia in response to bacterial challenge in the compromised primary olfactory pathway. J. Neuroinflamm. 9, 109. https://doi.org/10.1186/1742-2094-9-109 (2012). sourceSupported

Classified as probably not a substantial claim.

In a transgenic mouse model of familial Alzheimer's disease (5xFAD mice), intracranial injection with Salmonella typhimurium resulted in a dramatic increase in Aβ deposition after only 48 h.

“In a transgenic mouse model of familial Alzheimer’s disease (5xFAD mice, which exhibit the human amyloid precursor protein and presenilin 1 transgenes with five mutations linked to Alzheimer’s disease), intracranial injection with Salmonella typhimurium resulted in a dramatic increase in Aβ deposition after only 48 h13.”

• cites [13] Kumar, D. K. et al. Amyloid-beta peptide protects against microbial infection in mouse and worm models of Alzheimer’s disease. Sci. Transl. Med. 8, 340ra372. https://doi.org/10.1126/scitranslmed.aaf1059 (2016). sourceSupported

Classified as probably not a substantial claim.

The capacity to infect and survive inside glial cells is thought to be a key mechanism for the ability of bacteria to invade the CNS via cranial nerves.

“The capacity to infect and survive inside glial cells is thought to be a key mechanism for the ability of bacteria to invade the CNS via cranial nerves34,35.”

• cites [34] Macedo-Ramos, H. et al. Olfactory ensheathing cells as putative host cells for Streptococcus pneumoniae: Evidence of bacterial invasion via mannose receptor-mediated endocytosis. Neurosci. Res. 69, 308–313. https://doi.org/10.1016/j.neures.2010.12.015 (2011). sourcePartly supported

  The Discussion (page unavailable) proposes that olfactory ensheathing cells harboring Streptococcus pneumoniae could provide a route into the CNS, and the Methods describe recovering colony-forming bacteria from lysed host cells after infection. This supports the proposed mechanism for pneumococci via the olfactory route, but the paper does not establish it as a key mechanism for bacteria generally or for invasion via cranial nerves broadly. (LLM, conf=0.82)

  Experimental — accuracy not yet measured
• cites [35] Delbaz, A. et al. Neisseria meningitidis induces pathology-associated cellular and molecular changes in trigeminal schwann cells. Infect. Immun. https://doi.org/10.1128/IAI.00955-19 (2020). sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing).

Bag2 is a Bcl-2 associated co-chaperone gene that controls Hsp70 functionality.

“In addition, Bag2, a Bcl-2 associated co-chaperone gene which controls Hsp70 functionality was also downregulated leading to further failure of the system to protect cells from oxidative damage82.”

• cites [82] Qin, L., Guo, J., Zheng, Q. & Zhang, H. BAG2 structure, function and involvement in disease. Cell. Mol. Biol. Lett. 21, 1–11 (2016). sourceSupported

May combine two claims.

Aβ may be secreted as a normal immune response to any microbe that invades the nervous system, and if infection clears, deposited Aβ can be cleared by phagocytic glia.

“The secretion of Aβ may thus be a normal immune response to any microbe that may invade the nervous system, and if infection clears, the deposited Aβ can be cleared by phagocytic glia71.”

• cites [71] Ries, M. & Sastre, M. Mechanisms of abeta clearance and degradation by glial cells. Front. Aging Neurosci. 8, 160. https://doi.org/10.3389/fnagi.2016.00160 (2016). sourcePartly supported

  The Aβ Internalisation > Phagocytosis section (page not provided) says microglia phagocytose fibrillar Aβ, supporting clearance by phagocytic glia. The paper does not say that Aβ secretion is an immune response to invading microbes or that its deposits are cleared specifically after an infection resolves. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

Classified as probably not a substantial claim.

Chlamydia muridarum can quickly (within two days) enter the CNS via the olfactory and/or trigeminal nerves.

“We recently demonstrated that Chlamydia muridarum can quickly (within two days) enter the CNS via these paths24, suggesting that C. pneumoniae may also rapidly infect the brain via the nerves.”

• cites [24] Nazareth, L. et al. Chlamydia muridarum can invade the central nervous system via the olfactory and trigeminal nerves and infect peripheral nerve glial cells. Front Cell Infect. Microbiol. 10, 607779. https://doi.org/10.3389/fcimb.2020.607779 (2020). sourceSupported

May combine two claims.

Neuroinflammatory responses are considered a major driving factor in patients with neurodegeneration and Alzheimer's disease pathology, which starts early in the course of the disease, prior to the formation of Aβ plaques in the brain.

“Theses neuroinflammatory responses are considered a major driving factor in patients with neurodegeneration and Alzheimer’s disease pathology, which starts early in the course of the disease, prior to the formation of Aβ plaques in the brain73.”

• cites [73] Kinney, J. W. et al. Inflammation as a central mechanism in Alzheimer’s disease. Alzheimers Dement (N Y) 4, 575–590. https://doi.org/10.1016/j.trci.2018.06.014 (2018). sourcePartly supported

  The Overview and Inflammation in AD sections describe sustained neuroinflammation as a central feature of neurodegenerative disorders and a contributor to AD pathology. They do not establish that it begins before Aβ plaques form; the Microglia section instead describes Aβ as a hypothesized primary driver of microglial activation. The paper copy provides no page numbers for these passages. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

May combine two claims.

Chlamydiae can also persistently infect cells which is likely relevant for the link to chronic diseases.

“Chlamydiae can also persistently infect cells40 which is likely relevant for the link to chronic diseases1.”

• cites [40] Airenne, S. et al. Chlamydia pneumoniae infection in human monocytes. Infect. Immun. 67, 1445–1449 (1999). sourceSupported
• cites [1] Beagley, K. W., Huston, W. M., Hansbro, P. M. & Timms, P. Chlamydial infection of immune cells: Altered function and implications for disease. Crit. Rev. Immunol. 29, 275–305 (2009). sourceSupported

Classified as probably not a substantial claim.

Certain other bacteria have been shown to very rapidly (within days) reach the CNS via the olfactory and/or trigeminal nerves.

“Certain other bacteria, however, have been shown to very rapidly (within days) reach the CNS via the olfactory and/or trigeminal nerves reviewed in20.”

• cites [20] Dando, S. J. et al. Pathogens penetrating the central nervous system: Infection pathways and the cellular and molecular mechanisms of invasion. Clin. Microbiol. Rev. 27, 691–726. https://doi.org/10.1128/CMR.00118-13 (2014). sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The faster time-frame may be due to differences in inoculation dose since they used a higher dose than two previous studies but lower than another.

“which may be due to differences in the inoculation dose since we used a higher inoculation dose than two previous studies16,50 but lower than another18.”

• cites [16] Little, C. S., Hammond, C. J., MacIntyre, A., Balin, B. J. & Appelt, D. M. Chlamydia pneumoniae induces alzheimer’s-like amyloid plaques in brains of BALB/c mice. Neurobiol. Aging 25, 419–429. https://doi.org/10.1016/S0197-4580(03)00127-1 (2004). sourceNot checked — no full text of the source
• cites [50] Little, C. S. et al. Detection of bacterial antigens and Alzheimer’s disease-like pathology in the central nervous system of BALB/c mice following intranasal infection with a laboratory isolate of Chlamydia pneumoniae. Front. Aging Neurosci. 6, 304. https://doi.org/10.3389/fnagi.2014.00304 (2014). sourceSupported
• cites [18] van Boelen, E. et al. Detection of amyloid beta aggregates in the brain of BALB/c mice after Chlamydia pneumoniae infection. Acta Neuropathol. 114, 255–261. https://doi.org/10.1007/s00401-007-0252-3 (2007). sourceSupported

May combine two claims.

Following infection, activated microglia and astrocytes secrete pro-inflammatory cytokines, including IL-1β, TNFα and IL-6, which are neurotoxic and may directly increase Aβ production via activation of β-secretase (BACE).

“It has been shown that following infection, activated microglia and astrocytes secrete pro-inflammatory cytokines, including IL-1β, TNFα and IL-6 which are neurotoxic and may directly increase Aβ production via activation of β-secretase (BACE)66,74.”

• cites [66] Al-Atrache, Z., Lopez, D. B., Hingley, S. T. & Appelt, D. M. Astrocytes infected with Chlamydia pneumoniae demonstrate altered expression and activity of secretases involved in the generation of β-amyloid found in Alzheimer disease. BMC Neurosci. 20, 6–6. https://doi.org/10.1186/s12868-019-0489-5 (2019). sourcePartly supported

  The Background (page unavailable) links infectious stimuli to inflammatory cytokine release and altered BACE1 activity, and the Results report increased BACE1 activity after infection of astrocytoma cells. The paper does not show that infected microglia and astrocytes secrete the specified IL-1β, TNFα, and IL-6, or that those cytokines directly cause the increase in Aβ through BACE1. Its Discussion reports increased transcription of IL-1α, not IL-1β, in infected astrocytes. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [74] Alasmari, F., Alshammari, M. A., Alasmari, A. F., Alanazi, W. A. & Alhazzani, K. Neuroinflammatory cytokines induce amyloid beta neurotoxicity through modulating amyloid precursor protein levels/metabolism. Biomed. Res. Int. 3087475–3087475, 2018. https://doi.org/10.1155/2018/3087475 (2018). sourcePartly supported

  Section 2.2 reports that TNF-α and IFN-γ enhance β-secretase expression in an AD mouse model, with increased Aβ deposition. The Introduction also says inflammatory cytokines can cause neurodegeneration. Our copy does not establish the claimed sequence following infection or show that activated microglia and astrocytes secrete all three listed cytokines, including IL-6, to increase Aβ through β-secretase. Page numbers were not available in the indexed passages. (LLM, conf=0.87)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing).

Upregulation of Flt1 could reflect cognition impairment due to higher Aβ and Tau deposition in Alzheimer's disease etiopathogenesis.

“In contrast, upregulation of Flt1, a key gene in vascular endothelial growth factor (VEGF) regulation was a key feature in long term infection which could reflect cognition impairment due to higher Aβ and Tau deposition in AD etiopathogenesis, as observed in a previous study95.”

• cites [95] Mahoney, E. R. et al. Brain expression of the vascular endothelial growth factor gene family in cognitive aging and alzheimer’s disease. Mol. Psychiatry 26, 888–896 (2021). sourcePartly supported

  The Results (Associations with cognition and Associations with pathology; page unavailable) link higher FLT1 expression to worse cognitive trajectories and greater β-amyloid burden, but do not find a significant gene-level association with tau burden. The Discussion reports associations for some membrane-bound FLT1 isoforms with tau and says it is unclear whether expression changes are a cause or consequence of neuropathology. The proposed explanation involving both deposits therefore goes beyond what the study establishes. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing).

Cd2ap has been previously associated with Alzheimer's disease pathology aggravated by increased deposition of Aβ and Tau-induced neurotoxicity.

“In fact, the long-term infection was also associated with low expression of Cd2ap which has been previously associated with AD pathology aggravated by increased deposition of Aβ and Tau-induced neurotoxicity87.”

• cites [87] Tao, Q.-Q., Chen, Y.-C. & Wu, Z.-Y. The role of CD2AP in the pathogenesis of Alzheimer’s disease. Aging Dis. 10, 901 (2019). sourcePartly supported

  The Conclusions (page unavailable) link CD2AP loss of function to altered Aβ metabolism and Tau-induced neurotoxicity. The amyloidogenesis section discusses Aβ generation and levels, but does not establish that CD2AP loss increases Aβ deposition specifically. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

May combine two claims.

Mbp maintained myelination and prevented further neuroinflammation.

“Long term infection also induced Mbp gene, which maintained myelination and prevented further neuroinflammation94.”

• cites [94] Ou-Yang, M.-H. & Van Nostrand, W. E. The absence of myelin basic protein promotes neuroinflammation and reduces amyloid β-protein accumulation in Tg-5xFAD mice. J. Neuroinflamm. 10, 1–12 (2013). sourcePartly supported

  The Background identifies MBP as a major structural protein of the myelin sheath, and the Discussion links MBP loss and abnormal myelination to increased neuroinflammatory cells. The paper studies MBP-deficient mice; it does not show that infection-induced Mbp maintained myelination or prevented further inflammation during infection. (LLM, conf=0.84)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing).

Cdk18 is a cyclin-dependent kinase that usually functions to clear DNA damages.

“It led to higher expression of Cdk18 which is a cyclin-dependent kinase and usually functions to clear DNA damages88.”

• cites [88] Barone, G. et al. Human CDK18 promotes replication stress signaling and genome stability. Nucleic Acids Res. 44, 8772–8785 (2016). sourcePartly supported

  The Introduction identifies CDK18 as a cyclin-dependent kinase. The Results report that CDK18-depleted cells accumulate DNA damage and cannot efficiently repair DNA breaks by homologous recombination. This supports a role in the DNA-damage response, but the paper characterizes CDK18 chiefly as a regulator of replication-stress signaling, not as a kinase that usually clears DNA damage. (LLM, conf=0.84)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing).

Axl is a phagocytotic gene important in maintaining homeostatic levels of the major Alzheimer's disease related lipoprotein ApoE.

“Additionally, further protection was provided by increased Axl activity, a phagocytotic gene (autophagy) important in maintaining homeostatic levels of major AD related lipoprotein, ApoE93.”

• cites [93] Zhao, W. et al. Axl receptor tyrosine kinase is a regulator of apolipoprotein E. Mol. Brain 13, 1–13 (2020). sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing).

Sumf2 is associated with modulation of tissue homeostasis.

“Additionally, it also helped in sulfatase gene (Sumf2) maintenance which is associated with modulation of tissue homeostasis90.”

• cites [90] Roberts, R. O. et al. Decreased expression of sulfatase 2 in the brains of Alzheimer’s disease patients: Implications for regulation of neuronal cell signaling. J. Alzheimer’s Dis. Rep. 1, 115–124 (2017). sourceCould not verify

  The Introduction says SULF2 modulates homeostasis, but the claim names Sumf2. Searches for “SUMF2” and “Sumf2 maintenance” returned passages about SULF2, not Sumf2; our copy does not establish the claimed association for Sumf2. (LLM, conf=0.78)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Ezr and Cldn5 are associated with maintenance of actin cytoskeletal structure, synapse and tight junctions, respectively.

“Interestingly, long term infection also induced expressions of Ezr91 and Cldn592 which are associated with maintenance of actin cytoskeletal structure, synapse and tight junctions, respectively.”

• cites [91] Lanke, V., Moolamalla, S., Roy, D. & Vinod, P. Integrative analysis of hippocampus gene expression profiles identifies network alterations in aging and Alzheimer’s disease. Front. Aging Neurosci. 10, 153 (2018). sourceSupported
• cites [92] Yamazaki, Y. et al. Selective loss of cortical endothelial tight junction proteins during Alzheimer’s disease progression. Brain 142, 1077–1092 (2019). sourceSupported

May combine two claims.

C. pneumoniae could infect, survive in and replicate within glia from the PNS (OECs and TgSCs) and the CNS (astrocytes and microglia).

“We here showed that C. pneumoniae could infect, survive in and replicate (form inclusions) within glia from the PNS (OECs and TgSCs) and the CNS (astrocytes and microglia).”

May combine two claims.

In C. pneumoniae-infected mouse brains, 514 genes were up-regulated at day 7 and 232 genes at day 28 compared to non-infected controls, with 81 genes common to both.

“We found that a total of 514 genes were up-regulated in day 7 samples compared to 232 genes in day 28, out of which 81 genes were common to both and 433 (84.2%) were exclusively up-regulated in day 7 while 151 (65.1%) were exclusively up-regulated by day 28 (Fig. 7A).”

May combine two claims.

Despite isolating viable C. pneumoniae from the brain beyond the olfactory bulb, no definitive C. pneumoniae inclusions were found in brain tissue sections from these mice.

“Despite being able to isolate viable C. pneumoniae from the brain (beyond the bulb), we did not find definitive C. pneumoniae inclusions in brain tissue sections from these mice (not shown)”

May combine two claims.

Within the olfactory bulb, C. pneumoniae was only detected within the nerve fibre layer and glomerular layer, with inclusion bodies present inside OECs.

“Within the olfactory bulb, C. pneumoniae was only detected within the nerve fibre layer and glomerular layer, with C. pneumoniae inclusion bodies being present inside OECs (Fig. 3G).”

May combine two claims.

C. pneumoniae was detected within the olfactory mucosa and olfactory bulb 24 h after intranasal inoculation, and infectious C. pneumoniae were isolated from both the olfactory mucosa and olfactory bulb.

“24 h after inoculation C. pneumoniae was detected within the olfactory mucosa and olfactory bulb and infectious C. pneumoniae were isolated from both the olfactory mucosa and olfactory bulb (Supplementary Fig. 1).”

May combine two claims.

As a result of increased growth factor signalling, angiogenesis was induced with increased trophic activity demonstrating ongoing inflammatory activity.

“As a result of increased growth factor signalling, angiogenesis was induced with increased trophic activity demonstrating ongoing inflammatory activity.”

May combine two claims.

Injury to the nasal epithelium led to increased bacterial load in the peripheral nerves and olfactory bulb, but did not increase load in the rest of the brain during the time course of the study.

“We also showed that injury to the nasal epithelium led to increased bacterial load in the peripheral nerves and olfactory bulb, but did not increase load in the rest of the brain during the time course of our study.”

May combine two claims.

In the olfactory nerve and bulb, C. pneumoniae inclusions were associated with localized deposits of Aβ, which appeared in the olfactory nerve earlier than in the bulb.

“In the olfactory nerve and bulb, C. pneumoniae inclusions were associated with localized deposits of Aβ, which appeared in the olfactory nerve earlier than in the bulb.”

May combine two claims.

All these gene modulations led to increased unfolded protein response, oxidative stress, and higher disease association as evident by the biological processes heat map.

“Nevertheless, all these gene modulations led to increased unfolded protein response, oxidative stress, and had higher disease association as evident by the biological processes heat map.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Hspa4 helped in sulfatase gene (Sumf2) maintenance.

“Additionally, it also helped in sulfatase gene (Sumf2) maintenance which is associated with modulation of tissue homeostasis90.”

May combine two claims.

The nerves extending between the nasal cavity and the brain constitute invasion paths by which C. pneumoniae can rapidly invade the CNS likely by surviving in glia and leading to Aβ deposition.

“In summary, the nerves extending between the nasal cavity and the brain constitute invasion paths by which C. pneumoniae can rapidly invade the CNS likely by surviving in glia and leading to Aβ deposition.”

• AssumptionRests on an assumption: Findings in intranasally inoculated mice about C. pneumoniae CNS invasion and Aβ deposition are relevant to human late-onset Alzheimer's disease.

Probably not a substantial claim: may not pass S3 (load-bearing).

Intracellular pathogens like Chlamydia would benefit from UPR because increased folding capacity and activation of lipid biosynthesis can sustain bacterial replication.

“Intracellular pathogens like Chlamydia would benefit from UPR since increase in folding capacity and activation of lipid biosynthesis can sustain bacterial replication.”

Probably not a substantial claim: may not pass S3 (load-bearing).

The experimental procedures used in the study were conducted with the approval of the Griffith University Biosafety Committee and the Griffith University Animal Ethics Committee in accordance with guidelines.

“The experimental procedures used in the study were conducted with the approval of the Griffith University Biosafety Committee (NLRD/09/15_var7) and the Griffith University Animal Ethics Committee (MSC/08/18/AEC) in accordance with guidelines of the Australian Commonwealth Office of Gene Technology Regulator and the National Health and Medical Research Council of Australia.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Aβ oligomers have also been proposed to cause ER dysfunction leading to UPR-mediated neurotoxicity and neuronal cell death.

“Conversely, Aβ oligomers have also been proposed to cause ER dysfunction leading to UPR mediated neurotoxicity and neuronal cell death77.”

• cites [77] Hetz, C. & Mollereau, B. Disturbance of endoplasmic reticulum proteostasis in neurodegenerative diseases. Nat. Rev. Neurosci. 15, 233–249. https://doi.org/10.1038/nrn3689 (2014). sourceNot checked — no full text of the source

May combine two claims.

C. pneumoniae entered the CNS via nerves within 24-72 h after intranasal inoculation and without concurrent blood infection.

“C. pneumoniae entered the CNS via nerves within 24–72 h after intranasal inoculation and without concurrent blood infection”

May combine two claims.

Injury to the nasal epithelium exacerbated peripheral nerve infection, but reduced brain infection.

“injury to the nasal epithelium exacerbated peripheral nerve infection, but reduced brain infection”

Probably not a substantial claim: may not pass S3 (load-bearing).

All animal experiments in this study are reported in accordance with ARRIVE guidelines.

“All the animal experiments in this study are reported in accordance with ARRIVE guidelines (https://arriveguidelines.org).”

Probably not a substantial claim: may not pass S3 (load-bearing).

For comparison between groups, the same image capture settings, laser intensity and focal depths were used.

“For comparison between groups, the same image capture settings, laser intensity and focal depths were used.”

May combine two claims.

C. pneumoniae infection leads to differential regulation of Alzheimer's disease genes, with long-term infection (day 28) down-regulating most genes related to protein folding and aiding in misaggregation.

“In summary, these findings suggest that C. pneumoniae infection leads to a differential regulation of Alzheimer’s disease genes with long term infection (day 28) down-regulating most of the genes related to folding of proteins and aiding in misaggregation.”

May combine two claims.

Hspa1b (Hsp70-2) is associated with increased oxidative stress and initiation of Alzheimer's disease pathology.

“Most importantly there was downregulation of key protective heat shock protein (Hspa1b or Hsp70-2), associated with increased oxidative stress and initiation of AD pathology81.”

• cites [81] Clarimón, J., Bertranpetit, J., Boada, M., Tàrraga, L. & Comas, D. HSP70-2 (HSPA1B) is associated with noncognitive symptoms in late-onset Alzheimer’s disease. J. Geriatr. Psychiatry Neurol. 16, 146–150 (2003). sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Chlamydiae are obligate intracellular bacteria with a unique biphasic life-cycle.

“Chlamydiae are obligate intracellular bacteria with a unique biphasic life-cycle reviewed in36.”

• cites [36] Abdelrahman, Y. M. & Belland, R. J. The chlamydial developmental cycle. FEMS Microbiol. Rev. 29, 949–959. https://doi.org/10.1016/j.femsre.2005.03.002 (2005). sourceNot checked — no full text of the source

May combine two claims.

The duration of infection had a definite role in differential gene expression of Alzheimer's disease genes, as biological replicates from respective time points clustered together but away from each other as a group.

“This analysis showed that the duration of infection had a definite role as the individual biological replicates from respective time points clustered together but away from each other as a group.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The nerves are well-protected physically and immunologically by the nasal epithelium which exhibits powerful innate and adaptive immune system components; together with NALT, the epithelium constitutes the first defence against microbes.

“The nerves are well-protected physically and immunologically by the nasal epithelium which exhibits powerful innate and adaptive immune system components. Together with the associated nasopharynx-associated lymphoid tissue (NALT), the epithelium constitutes the first defence against microbes25.”

• cites [25] Wu, H. Y. & Russell, M. W. Nasal lymphoid tissue, intranasal immunization, and compartmentalization of the common mucosal immune system. Immunol. Res. 16, 187–201 (1997). sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing).

In APP/PS1 mice, the terminal end of the olfactory nerve within the nasal olfactory epithelium is the first nervous system area to exhibit Aβ deposition, which then progresses to the olfactory bulb and other CNS areas.

“one study in an Alzheimer’s disease mouse model (APP/PS1 mice) showed that the terminal end of the olfactory nerve within the nasal olfactory epithelium is the first nervous system area to exhibit Aβ deposition, which then progresses to the olfactory bulb and other CNS areas72.”

• cites [72] Wu, N., Rao, X., Gao, Y., Wang, J. & Xu, F. Amyloid-beta deposition and olfactory dysfunction in an Alzheimer’s disease model. J. Alzheimer’s Dis. 37, 699–712. https://doi.org/10.3233/JAD-122443 (2013). sourceNot checked — no full text of the source

May combine two claims.

Persistent Chlamydia infection can last for many years, and the persistent Chlamydia bacteria can re-activate.

“Persistent Chlamydia infection can last for many years, and the persistent Chlamydia bacteria can re-activate41,42.”

• cites [41] Dean, D., Suchland, R. J. & Stamm, W. E. Evidence for long-term cervical persistence of Chlamydia trachomatis by omp1 genotyping. J. Infect. Dis. 182, 909–916. https://doi.org/10.1086/315778 (2000). sourceNot checked — no full text of the source
• cites [42] Hammerschlag, M. R. et al. Persistent infection with Chlamydia pneumoniae following acute respiratory illness. Clin. Infect. Dis. 14, 178–182. https://doi.org/10.1093/clinids/14.1.178 (1992). sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing).

Disturbance of endoplasmic reticulum function is emerging as a relevant factor driving neurodegeneration in Alzheimer's disease.

“Disturbance of endoplasmic reticulum (ER) function is emerging as a relevant factor driving neurodegeneration in Alzheimer’s disease77.”

• cites [77] Hetz, C. & Mollereau, B. Disturbance of endoplasmic reticulum proteostasis in neurodegenerative diseases. Nat. Rev. Neurosci. 15, 233–249. https://doi.org/10.1038/nrn3689 (2014). sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

RBs replicate in inclusions (modified cellular vacuoles), which expand in size as the bacteria replicate.

“RBs replicate in inclusions (modified cellular vacuoles), which expand in size as the bacteria replicate.”

• cites [36] Abdelrahman, Y. M. & Belland, R. J. The chlamydial developmental cycle. FEMS Microbiol. Rev. 29, 949–959. https://doi.org/10.1016/j.femsre.2005.03.002 (2005). sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing).

Primary glial cultures with approximately 70-80% purity were used in the experiments.

“Primary glial cultures with approximately 70–80% purity was used in the experiments.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Outside of host cells, Chlamydiae exist as infectious, biologically inactive elementary bodies (EBs), which exhibit strong resistance to environmental stress.

“Outside of host cells, Chlamydiae exist as infectious, biologically inactive elementary bodies (EBs), which exhibit strong resistance to environmental stress.”

• cites [36] Abdelrahman, Y. M. & Belland, R. J. The chlamydial developmental cycle. FEMS Microbiol. Rev. 29, 949–959. https://doi.org/10.1016/j.femsre.2005.03.002 (2005). sourceNot checked — no full text of the source

May combine two claims.

Long-term infection induced greater organisation of neuronal cytoskeleton and/or dendritic structure while also maintaining synaptic transmission and reuptake.

“This ensured that long-term infection induced greater organisation of neuronal cytoskeleton and/or dendritic structure while also maintaining synaptic transmission and reuptake.”

May combine two claims.

The nerves extending between the nasal cavity and the brain constitute invasion paths by which C. pneumoniae can rapidly invade the CNS and trigger genetic and molecular changes in the longer term which may contribute to the onset of Alzheimer's disease pathogenesis.

“From these results, we conclude that the nerves extending between the nasal cavity and the brain constitute invasion paths by which C. pneumoniae can rapidly invade the CNS and trigger genetic and molecular changes in the longer term which may contribute to the onset of Alzheimer’s disease pathogenesis.”