Human immunodeficiency virus-1(HIV-1) and hepatitis C virus (HCV) co-infection are two
rapidly growing epidemics and health concerns strongly driven by injection drug use (IDU) in
Kenya and the entire world. Inflammatory cytokines are important mediators of the host
response to HIV-1 and HCV infections including injection drugs. However, the molecular
interaction between HIV-1 and HCV co-infection and correlation with injection drug use is
largely undefined. Therefore, this cross-sectional study determined plasma levels of interferon
(IFN)-, interleukin (IL)-10, adiponectin and their association with CD4+ T cell count, HIV-1
viral load and basal metabolic index (BMI) in HIV-1 and HCV mono-infected antiretroviral
(ART)-naive (n=18) and -exposed (n=38); and co-infected ART-naive (n=5) and -exposed
(n=14); and uninfected (n=24) IDUs and healthy controls (n=27). One hundred and thirty five
injection drug users and 27 healthy controls were recruited from Bomu Medical Center,
Mombasa, Kenya through outreach and respondent driven sampling methods. Social
demographic information including drug use histories were collected from the study subjects
upon enrolment into the study through structured interview schedules with open- and closedended
questions. Plasma cytokines levels were determined using Enzyme linked Immunosorbent
assay (ELISA) technique, CD4 T cell count were enumerated using FacsCaliburTM flow
cytometry, HIV-1 viral load through polymerase chain reaction (PCR), and HIV-1 and HCV
infections determined by rapid sero-diagnosis. Interferon (IFN)- levels differed across-group
(P<0.0001) and were significantly elevated in HIV-1 mono-infected ART-exposed and
uninfected individuals relative to healthy controls (p<0.0001). Interleukin (IL)-10 levels also
varied across-group (P<0.0001) and were higher in HIV-1 and HCV co-infected ART-exposed,
HCV mono-infected and uninfected IDUs compared to healthy controls (p<0.0001).
Adiponectin levels varied across-group (p<0.0001) and were significantly higher in HCV monoinfected
compared to HIV-1 mono-infected ART-exposed or -naive (p<0.0001). Interferon-
(IFN-)/IL-10 ratio differed across-group (P<0.0001) and was increased in HIV-1 and HCV coinfected
ART-exposed, HCV mono-infected, HIV-1 mono-infected ART-exposed, and
uninfected groups relative to healthy controls (P<0.0001). Interferon- (IFN-) was correlated
with BMI (=-0.628; P=0.029) in HIV-1 and HCV co-infected ART-exposed, viral load (=-
0.998; P=0.004) in HIV-1 and HCV co-infected ART-naive, CD4+ T cell count (=-0.393;
P=0.018) in HCV mono-infected IDUs. Interferon- (IFN-) was also correlated with IL-10 in
HIV/HCV co-infected ART-exposed (r=0.711, p=0.010), HIV mono-infected ART-naive
(r=0.616, p=0.011), healthy controls (r=0.877, p< 0.0001), adiponectin (r= -0.422, p=0.013) in
ART-exposed HIV-1 mono-infected IDUs. Taken together, these results suggest profound
dysregulation in IFN- and IL-10 production that is associated with clinical outcomes in both
HIV-1 and HCV mono- and co-infected and uninfected IDUs. The implications of these findings
include their utility in initiation and monitoring of treatment in IDUs.