Correlates and outcomes of high inflammatory cytokine levels in ART naive Kenyan children diagnosed with HIV at hospital enrollment

Background: Cytokines are the key mediators of innate and adaptive immunity and the key modulators of inflammation during acute illness. Owing to the immune dysregulation and inflammation during HIV-infection, multiple studies have reported the association of inflammatory cytokines with increased mortality and other adverse clinical outcomes in people living with HIV (PLH) regardless of antiretroviral therapy (ART) status. However, very few studies have investigated the predictors of inflammatory cytokines and their association with adverse clinical outcomes in children living with HIV (CLHIV). The objective of our study was to identify the correlates of high proinflammatory cytokine levels at hospital admission and whether high cytokine levels were associated with an increased risk of death and prolonged hospitalization among newly diagnosed hospitalized CLHIV. Methods:Cytokine levels were measured in repository serum specimens from a prior randomized clinical trial of hospitalized Kenyan CLHIV, who were diagnosed with HIV infection at hospital admission, and randomized to initiate ART either urgently or after medical stabilization. Based on the distribution of cytokine levels, the cytokines were treated as either binary (detected/undetected) (IL-1β, Il-2, TNF-α, IFN-gamma, IL-4, IL-10, IL-13) or continuous (IL-6, IL-8, IL-12p70) for the analyses. Cytokines IL-1β, IL-2, IL-6, and TNF-α were selected as primary cytokines of interest given their association with mortality in the critical care literature. Primary study endpoints were defined a priori as death within six months of hospital admission, the combined end point of death or continued hospitalization at 15 days, and the mean duration of hospitalization. The potential correlates of cytokines were selected from existing literature and assessed using Poisson regression models for binary outcomes and linear regression models for continuous outcomes. Linear regression was used to assess the association between cytokine levels and duration of hospitalization in survivors. Cox regression and Kaplan-Meier survival analysis were used to estimate 6-month hazard ratios and median time to death. Poisson regression was used to estimate the relative risk of the combined endpoint. All analyses were adjusted for age and sex at admission. Results:Of 181 CLHIV in the overall RCT, a total of 104 children had sufficient enrollment serum for cytokine testing. IL-6 and IL-8 were detected in nearly all children (103 for each cytokine, 99.04%) children while IL-1β was detectable in only 7 children (6.31%). After adjusting for age and sex at enrollment, higher baseline C-reactive protein (CRP) ([adjusted coefficient (aCoefficient)] = 0.008 [95% CI = 0.00, 0.001, p=0.04]), higher CD4% (aCoefficient = 0.04 [95% CI = 0.00, 0.08, p=0.029]) and lower CD4% <15 (aCoefficient = -0.86 [95% CI = -1.59, -0.14] p=0.02]) were associated with higher IL-6 levels. Total neutrophil count ([adjusted Prevalence Ration (PR)] = 0.82 [95% CI = 0.72, 0.94], p=0.004) and hemoglobin level (g/dL) ([aPR] = 0.84 [95% CI = 0.72, 0.98], p=0.027) were independently associated with decreased IL-2 detection. Higher log10 CMV DNA levels (adjusted prevalence ratio [aPR] = 8.50 [95% CI = 1.99, 36.25], p=0.004) were independently associated with increased IL-1β detection. Meanwhile, the recruitment site (Kisumu) ([aPR] = 0.12 [95% CI = 0.015, 0.97], p=0.047) and administration of steroid at enrollment ([aPR] = 3.97e-07 [95% CI = 1.20e-07, 1.32e-06], p<0.01) were significantly associated with decreased IL-1β detection in the adjusted analysis. We did not identify any significant correlates of TNF-α. In adjusted analyses, each doubling of IL-6 levels (1-log2 increase) was associated with a 27% increased hazard of death ([aHR] = 1.27, [95% CI = 1.07, 1.50]). None of the other cytokines were associated with 6-month mortality risk or the combined outcome. Additionally, there was no association between any cytokines and the duration of hospitalization. Conclusion:IL-2 and Inflammatory cytokines were detected at high levels in this cohort of hospitalized newly diagnosed CLHIV. IL-1β detection was positively associated with CMV DNA levels and was negatively associated with the receipt of steroids IL-6 levels were associated with biomarkers of inflammation (CRP), and severe immunosuppression, and higher IL-6 level was independently associated with an increased hazard of death over 6-months in ART-naive Kenyan CLHIV diagnosed at hospital admission. Our study provides some novel insights into the immunological status and prognosis of severely ill, ART-naive CLHIV, highlighting the importance of inflammation in critical care outcomes in this population.
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