Severity of intestinal disease following Campylobacter jejuni infection correlates with level of TNF-α production and macrophage apoptosis (42.6)

Abstract Campylobacter jejuni causes diarrhea ranging from mild to bloody.Penetration of epithelial barrier allows organisms to interact with macrophages inducing proinflammatory cytokines. Infection of macrophages induces apoptosis, potentially leading to immune evasion or suppression. We investigated invasiveness, cytokine production and apoptosis of the human monocytic cell line THP-1 using three human C. jejuni isolates. To determine invasiveness,THP-1 cells were infected in vitro,treated with Gentamicin, lysed and plated. Cytokine mRNA expression was determined by semi quantitative multiplex RT-PCR and protein by ELISA.Apoptosis was determined by flow cytometry following Annexin V and TUNEL staining of infected cells. In vitro invasiveness of isolates correlated with disease severity. The isolate from severest disease(3915) was most invasive and the least invasive isolate was from the patient with mildest disease(115) while the third isolate from a patient with intermediate severity(417) fell in between. Cytokine message and expression(IL-1β,TNF-α and IL-8) was highest with 3915 followed by 417 and the least being 115. Differences between the three isolates were most prominent in TNF-α where mRNA expression following 3915 infection was about 3x of 417 and about 7x of 115. ELISA showed similar differences. 60.7% of 3915 cells underwent apoptosis while 417 induced 42.3% and 115 only 30%. We suggest that severity of disease is related to levels of TNF-α production and apoptosis.