Hans Norrgren [1], Kajsa Ström [2], Fredrik Månsson [3], Antonio Biague [4], Zacarias José Da Silva [4], Joakim Esbjörnsson [5], Marianne Jansson [6], Patrik Medstrand [5], Kristina Jakobsson [7], Jacob Lindman [1] for the SWEGUB CORE group
Affiliates: [1] Department of Clinical Sciences Lund, Division of Infection Medicine, Lund University, Lund, Sweden. [2] Faculty of Medicine, Lund University, Lund, Sweden. [3] Department of Clinical Sciences, Infectious Diseases Research Unit, Lund University, Malmö, Sweden. [4]National Public Health Laboratory, Bissau, Guinea-Bissau. [5]Department of Experimental Medical Science, Lund University, Lund, Sweden. [6] Department of Laboratory Medicine, Lund University, Lund, Sweden [7] Department of Occupational and Environmental Medicine, Gothenburg University, Sweden.

HIV-2 infected individuals have in general lower risk of transmission and slower progression to AIDS compared to HIV-1 positive subjects. It is yet unclear why some HIV-2 positive subjects develop immunodeficiency while some remain long-term non-progressors. Persistent organic pollutants (POPs) have many negative effects on the human health and by working as endocrine disruptors these substances can affect the immune system inducing autoimmune diseases, allergy, diabetes mellitus and cancer. In a previous study we have found high levels of POPs in HIV-negative subjects in Guinea-Bissau and in the present study we aimed to explore if exposure to POPs may have an inverse effect on disease progression to AIDS among HIV-2 infected subjects in Guinea-Bissau.

The individuals in this study were selected from a cohort of police officers in Guinea-Bissau. Inclusion to this cohort started in 1990 and continued until 2009. Group 1 (progressors) consisted of participants positive for HIV-2 at the time of inclusion and with disease progression to AIDS within 10 years of clinical follow-up (n=30). Group 2 (non-progressors) consisted of participants positive for HIV-2 at inclusion without severe HIV-associated symptoms at inclusion or during at least 10 years of follow-up (n=37). The serum samples were analyzed for 21 different POPs. Values of serum levels below the LOQ (limits of quantification) for each POP were set to half of this limit. POPs with more than 50% of the results below LOQ were excluded. The association between POP exposure and disease progression was first evaluated with the Mann-Whitney test and then with a multivariate analysis using tertiles of POPs based on the distribution among non-progressors controlled for age and sex.

Median age was higher among progressors (37.5 years interquartile range (IQR) 32-47) vs non-progressors (34 years IQR 31-38) (p<0.05). Men had higher levels of POPs from almost all classes and individuals ≥30 years had higher levels of several congeners of polychlorinated biphenyls compared to younger individuals. In the univariate analysis a slightly higher level of dichlorodiphenyltrichloroethane (DDT) among non-progressors and a trend for higher levels of β-hexachlorocyclohexane (β-HCH) among progressors (p=0.1) was noted. To reinforce the difference between the study groups the study population was divided in two new comparison groups. In one group we included subjects with progression to AIDS within 5 years (n=23), and in the other group subjects with no progression to WHO clinical stage 3 or 4 within 15 years of observation were included (n=18). The levels of β-HCH was now significantly higher among fast-progressors compared to long term non-progressors (p<0.05). However in the multivariate regression analysis no significant difference could be found between the four study groups for any of the POPs including β-HCH.

This study is the first to evaluate the effect of POPs on the clinical progression in HIV-infected individuals. We could not find any association between high levels of POPs and the risk of developing AIDS in HIV-2 infected subjects in Guinea-Bissau, but further studies of the association between exposure to environmental toxic agents and the development of other immune disturbances are of great importance worldwide. The levels of POPs were high which call for urgent regulatory measures.