Analysis of blood plasma cytokine profile in healthy residents of the Republic of Guinea
Authors: Arsentieva N. A. , Lyubimova N. E. , Batsunov O. K. , Semenov A. V. , Totolian A. A. 
Published: August 2020

The cytokine system is a large group of humoral factors  produced by immune cells and involved in the  pathogenesis of most  human diseases.  To assess the  significance of changes  in cytokines/chemokines under  pathological conditions, appropriate reference values are required for healthy  people.  As known  from existing literature, most studies of various cytokine/chemokine concentrations in blood plasma were performed in healthy  subjects from Western Europe and North America.  Certain inter-population differences are known, with  respect  to production of distinct cytokines in different  racial  and  national groups.  Only  single studies concern normal levels of distinct cytokines in blood  plasma  of healthy  African  residents. The purpose  of this study was to determine the blood plasma cytokine profile in healthy  residents of the Republic of Guinea (RG), and to establish normal cytokine values.

We have  examined 24  healthy  RG  residents and  23  residents of St.  Petersburg. Concentrations  of 40 cytokines/chemokines were determined in blood plasma.  The study was performed using multiplex analysis by xMAP technology.

The  following  cytokine/chemokine levels  were  significantly   increased in  the  blood  plasma  of the  RG residents: IFNγ, IL-2, IL-4, IL-6, IL-10, TNFα, CCL1/I-309, CCL3/MIP-1α, CCL7/MCP-3, CCL17/ TARC, CCL19/MIP-3β,  CCL20/MIP-3α,  CCL21/6Ckine, CXCL2/Gro-β,  CXCL5/ENA-78, CXCL6/ GCP-2, CXCL9/MiG, CX3CL1/Fractalkine (р < 0.001).  For  the  CCL8/MCP-2, CCL22/MDC, CXCL1/ Gro-α and CXCL12/SDF-1α+β chemokines a trend for increased concentration was revealed, in comparison with residents of St. Petersburg (р < 0.05). Moreover, the levels of CCL23/MPIF-1 and MIF were significantly lower (р < 0.0001) in the RG residents. There was a tendency for decreased levels (р < 0.05) for CCL2/MCP-1 and CCL24/Eotaxin-2 chemokines in blood plasma taken from RG residents. There were no differences in levels of cytokines/chemokines for the studied  groups: GM-CSF, IL-1β, IL-16, CCL11/Eotaxin, CCL13/MCP-4, CCL15/Leukotactin-1, CCL25/TECK, CCL26/Eotaxin-3, CCL27/CTACK, CXCL8/IL-8, CXCL10/IP-10, CXCL11/I-TAC, CXCL13/BCA, and  CXCL16/SCYB16. Hence, this study  has presented for the  first time the normal limits for a wide range of cytokines/chemokines in blood plasma  of the African inhabitants. Interpopulation differences were found, including those  for constitutive chemokines. Different levels of CCL19/ MIP-3β and CCL21/6Ckine chemokines (the CCR7 receptor ligands) for the two populations may indirectly indicate the physiological features of T-cell maturation. Increased levels of CXCR2 receptor ligands in the blood plasma  of Guineans, i.e.,  CXCL2/Gro-β, CXCL5/ENA-78 and  CXCL6/GCP-2, may be due  to additional function of these chemokines as ligands for atypical DARC chemokine receptor, which neutralizes chemokines from the blood flow, whereas 95% of West Africans have mutations in the DARC gene and do not express this receptor. Increased levels of proinflammatory IL-6  and TNFα cytokines, and chemokine CCL20/MIP-3α in blood plasma  from RG  residents may suggest inflammatory processes  in the liver, since 100% of the examined Guineans had antibodies against the hepatitis A virus, 48% had antibodies to hepatitis B virus (anti-HBs), and 12% had antibodies against hepatitis C virus. In summary, the differences in cytokine/chemokine level may be related  to specific environment, circulation of infectious diseases, composition of intestinal, skin and mucosal microbiota, as well as distinct genetic  features.