TDP-43 protein inclusions are found inside nerve cells, in Parkinson’s, ALS, MS, and now LATE dementia. One study proposed TDP-43 proteins move intracellularly. It is unclear how a protein could move intracellularly, from cell-to-cell, unaided; because proteins are not alive and cannot be killed.

Chlamydia pathogens live intracellularly, spread through migration and metastasis, disperse abnormal proteins, cause inclusions, and generate an immune response. It is reasonable to suggest one or more forms of chlamydia generate TDP-43 proteins; and as the pathogen spreads to new cells, forms and disperses new TDP-43 proteins. The pathogen and/or the immune response traps TDP-43 proteins inside inclusions.

Other pathogens may also generate TDP-43, and chronic diseases may be triggered by a single pathogen or a combination of pathogens.

https://www.researchgate.net/publication/284547142_TDP43_is_intercellularly_transmitted_across_axon_terminals