Background: Chlamydia pneumoniae (Cpn) is one of the most common respiratory pathogens in children and adults. It is characterized as an obligate intracellular parasite. Peripheral blood monocytes (PBMC), lymphocytes, and macrophages are involved in spreading chlamydia infection to extrapulmonary organs indicating that Cpn infection can cause systematic symptoms in vivo via blood transmission.
Methods: This review summarizes the mechanisms of Cpn infection in host cells, the immune response of the body, and the relationship between Cpn infection and some chronic diseases.
Results: Cpn participation in extrapulmonary chronic diseases has been proven owing to the presence of Cpn DNA in AS plaque, nerve tissues, and synovium tissues of the joints.
Conclusions: Cpn infection is related to the development of chronic diseases such as atherosclerosis, Alzheimer's Disease (AD), and reactive arthritis through in vivo and in vitro experiments.