Abstract
BackgroundIt is not known if there is a difference in the immune response to syphilis between HIV-infected and uninfected individuals.MethodsWe prospectively recruited all patients with a new diagnosis of syphilis and tested their plasma for IFNα, IFNγ, IL-1β, IL-12p40, IL-12p70, IP-10, MCP-1, MIP-1α, MIP-1β, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10 and IL-17A at baseline pre-treatment and 6 months following therapy.ResultsA total of 79 HIV-infected [44 primary/secondary syphilis (PSS) and 35 latent syphilis (LS)] and 12 HIV-uninfected (10 PSS and 2 LS) cases of syphilis and 30 HIV-infected controls were included in the study. At the baseline visit, compared to the control group, concentrations of IL-10 were significantly elevated in the HIV-infected and uninfected groups. The level of IL-10 was significantly higher in the HIV-infected compared to the HIV-uninfected PSS group (25.3 pg/mL (IQR, 4.56–41.76) vs 2.73 pg/mL (IQR, 1.55–9.02), P = 0.0192). In the HIV-infected PSS group (but not the HIV-infected LS or HIV-uninfected PSS groups) the IP-10, MIP-1b, IL-6 and IL-8 were raised compared to the controls. IL-10 levels decreased but did not return to control baseline values by 6 months in HIV infected PSS and LS and HIV uninfected PSS.ConclusionPSS and LS in HIV-infected individuals is characterized by an increase in inflammatory and anti-inflammatory cytokines such as IL-10. The increase of IL-10 is greater in HIV-infected than uninfected individuals. Further work is required to ascertain if this is part of an immunological profile that correlates with adverse outcomes such as serofast syphilis and neurosyphilis, in HIV-infected individuals.
Highlights
It is not known if there is a difference in the immune response to syphilis between Human Immunodeficiency Virus (HIV)-infected and uninfected individuals
Except for a higher HIV viral load in the controls than the primary/secondary syphilis (PSS) and latent syphilis (LS) groups, there was no significant difference in the age, CD4 T cell count, percent on antiretroviral therapy (ART) or HIV viral load between the controls and HIVinfected syphilis patients
The positive correlations we found between IL-10 and IL-12p40, IL-12p70, MIP1α, Macrophage Inflammatory Protein (MIP)-1β, IL-5, IL-6, IL-7 and IL-8 in the HIVinfected PSS group could be interpreted as evidence that the increased IL-10 is acting as a feedback response to limit inflammation
Summary
It is not known if there is a difference in the immune response to syphilis between HIV-infected and uninfected individuals. A number of studies have found the natural course of syphilis to be altered in HIV-infected patients. There is evidence that neurosyphilis may occur more frequently, at. These findings generate the hypothesis that the immune responses to syphilis differ by HIV-infection status. Most previous studies have characterized the immune response to syphilis in animal models or in HIV-uninfected individuals [14,15,16,17,18,19,20]. The only study that we are aware of that has included an HIV-infected population was weakened by its retrospective study design, Kenyon et al BMC Infectious Diseases (2017) 17:111 small sample size, small number of cytokines evaluated and lack of HIV-uninfected and healthy HIV-infected control groups [21]
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