Effect of HIV and chlamydia infection on rectal inflammation and cytokine concentrations in men who have sex with men

Asymptomatic Chlamydia trachomatis infections are common in HIV-infected men who have sex with men (MSM). Although C. trachomatis combined with HIV would be likely to enhance inflammation, the asymptomatic course suggests otherwise. We assessed local inflammation, mucosal damage, and cytokine concentrations in rectal mucosal fluid samples from patients with HIV (with or without the use of combination antiretroviral therapy [cART]) and with or without the presence of rectal C. trachomatis. Rectal swabs from 79 MSM (with and without C. trachomatis, HIV, and cART use) who reported a history of receptive anal sex were analyzed for neutrophil activation (measured by myeloperoxidase [MPO]), mucosal leakage (measured by albumin and alpha-2-macroglobulin), and proinflammatory and anti-inflammatory cytokines. C. trachomatis infection, HIV infection, and cART use in MSM had no differential effects on rectal neutrophilic inflammation and mucosal damage. Interleukin 8 (IL-8) was found to correlate with MPO, and MPO correlated with markers of mucosal damage. In HIV-negative participants, men with C. trachomatis infection had lower concentrations of monocyte chemotactic protein 1 (MCP-1), IL-1α, and IL-1 receptor antagonist (IL-1RA) than men without rectal C. trachomatis infection (P = 0.005, 0.007, and 0.07, respectively). We found no difference in anal cytokine concentrations in HIV-infected participants in relation to the presence of C. trachomatis infection or cART use. In participants with rectal C. trachomatis infection, those who were HIV negative had lower median concentrations of IL-8 and IL-1α than those with HIV (P = 0.05 and 0.06, respectively). The slope of the regression line between MPO and IL-8 was reduced in participants with rectal C. trachomatis infection. C. trachomatis dampens cytokine concentrations but not in HIV-infected patients. The extent of mucosal damage was comparable in all patient groups. The apparent reduced neutrophil response to IL-8 in HIV-infected patients with C. trachomatis infection is in accordance with its asymptomatic course