Comparison Of Cytokines And Chemokines In QFT Positive And Negative House Hold Contacts Of TB Patients

Abstract

Abstract Background: Tuberculosis (TB) is a highly contagious bacterial infection caused by Mycobacterium tuberculosis(MTB). It is the leading cause of death worldwide resulting in approximately 1.6 million deaths annually, yet only a small fraction of those infected with TB ever develop the illness depending on the host’s immune status. Our immune system fight pathogens by secretion of chemicals called cytokines. Cytokines are substances released to help our bodies fight infection and their levels can determine if we are infected or not. These cytokines serve multiple purposes: they stimulate the immune response; inhibit bacterial growth; and induce cell-death. Together these actions protect us from MTB infections by eliminating infected cells and limiting further spread of bacteria. Objective: Comparison Of Cytokines And Chemokines In QFT Positive (LTBI) And Negative House Hold Contacts Of TB Patients Methods: The study was conducted inhouse hold contacts of TB patients and Community controls from selected health facilities in Addis Ababa, Ethiopia. A Comparative cross-sectional study was used from April 2022 to September 2023. Study involed three groups; Household contacts of TB patients (QFT Negative and QFT positive group(LTBI)) and Community controls with total sample size of 65 were recruited. Socio demographic data was collected using structured questionnaires and blood sample of participants were drawn and the QuantiFERON assay which contains TB antigen tubes(TB1 and TB2) coated with ESAT-6 and CFP-10 peptides to stimulate IFN-γ production. The QuantiFERON assay was performed on House Hold contacts of TB patients (QFT Negative group 16 and QFT positive group(LTBI) 21) and Community controls (CC of QFT Negative group) 28 participants. Cytokine analysis was performed using Luminex technology. Statistical analysis was done using GraphPad Prism 9.5 and Statistical Package for Social Sciences (SPSS). The unstimulated level (Nil) and the background-corrected TB stimulated level (TB1 and TB2 -Nil) of each marker were included as separate variables in the statistical analyses. The Kruskal-Wallis test (the ANOVA one-way non-parametric multiple comparison test coupled to the Dunn’s multiple comparison test was used to detect differences between the study groups. A p-value <0.05 with a 95% confidence interval was considered statistically significant. Results: When assessing socio-demographic, behavioral, clinical and hematological parameters of all participants, the majority were female including 82% (n=23) of CCs, 76% (n=16) of LTBIs, iii and 69% (n=11) of . HHC QFT negative Regarding age distribution, the majority of participants across the three groups were in the 26-35 years category, with 29% of CCs, 43% of LTBIs, and 38% of HHC QFT negative in this age range. In terms of BCG vaccination scar, 46% of HCCs, 33% of LTBIs, and 56% of resistors had a visible scar present. Latently infected participants have shown higher levels of proinflammatory molecules like IFN-γ (p<0.0001), IFN- α (p=0.0074), IL1RA(p<0.0001), IL2(p<0.0001), IL12(p=0.0464), IL17A(p=0.0002), IL17F(p=0.0015) compared to HHC QFT negative and Community Controls. Likewise, the level of chemokines like MCP-1(p<0.0001), MIP-1β(p<0.0001), IP-10(p<0.0001), and MIG(p<0.0001) were significantly higher in the LTBI group as compared to HHC QFT negative and Community Controls. The growth factors FGF basic(p=0.0175), GCSF(p=0.0009), GMCSF(p<0.0001), VEGF(p=0.0104), as well as immunoregulatory cytokines like IL-2R(p=0.0002), IL-13(p=0.0172), IL-15 (p=0.0248) and IL-9(p=0.0361) and anti-inflammatory cytokine IL-22 were also significantly higher in HHC QFT negative groups compared with the other two groups. The following cytokines have no statistically significant difference between the groups (p> 0.05) TNF-α, IL-1α, IL-1 β, IL-3, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, RANTES, MIP-1α, Eotaxin, EGF, HGF. Conclusion: The observed cytokine profile difference indicates that LTBI individuals show a distinct immunological signature that distinguishes them from HHC QFT negative and Community Controls in that they have heightened proinflammatory cytokines, chemokines, growth factors, and immunoregulators and Anti-inflammatory cytokines. This indicates a sustained activation of the immune system in LTBI individuals which controls the infection from activation. Our findings could help in understanding the interaction of the immune system with MTB infection for therapeutics and vaccine delivery and development Recommendation: Further research should delineate immune cell phenotypes and antimicrobial functions across infection stages to identify correlates of protection. Keywords: TB, Cytokine and chemokine , QFT Assay, Luminex Assay.