One-month assessment of Th-cell axis related inflammatory cytokines, IL-17 and IL-22 and their role in alcohol-associated liver disease

Abstract

Introduction: Changes in the expression of cyto- and chemokines due to alcohol-associated liver disease (ALD) have been reported to be both protective and pathogenic. This study examined plasma levels of two key cytokines, Il-17 and Il-22, which construct the proinflammatory vs. anti-inflammatory axes across the spectrum of alcohol use disorder (AUD) and ALD including alcohol-associated hepatitis (AH) to determine the underlying status of the inflammation.

Methods: Forty-two males and females aged 25-63 yrs. were grouped as healthy controls (HV[n=8]), AUD with no liver injury (AUDNLI [n=8]), AUD with liver injury (AUDLI [n=8]), non-severe alcohol-associated hepatitis (NSAH [n=9]), and severe alcohol-associated hepatitis (SAH [n=9]). Demographic, drinking, and clinical data were collected. Blood samples were collected at baseline (BL, all subjects) and during week 4 (W4, only patients) for IL-17 and IL-22; and statistically analyzed.

Results: IL-17 was highly elevated in the SAH group both at BL and post-SOC. LTDH and BL IL-22 in non-severe AH patients were associated significantly. LTDH significantly predicted W4 IL-22 levels, positively (increasing) in NSAH and inversely (lowering) in SAH patients. BL and W4 IL-22 levels were significantly higher (4-fold, p≤0.001) in all AH patients compared to all AUD patients (AUROC=0.988, p≤0.001). IL-22 showed significant affinity with AST, AST: ALT ratio, total bilirubin, INR, and PT both at BL and W4. IL-22 was inversely associated with IL-1β; and positively with TNF-α and IL-8 both at BL, and W4. BL IL-17 showed a positive correlation with MELD (p=0.017) in all AH patients. In SAH, > 2-fold W4 IL-17 level compared to BL showed significant within subjects' effects, p=0.006. In AUD patients without AH, the drop in IL-17 at W4 vs. BL showed a significant within subjects' effect, p=0.031.

Discussion: Drinking chronicity predicted opposite effects in IL-22 levels in NSAH (antiinflammatory) and SAH (pro-inflammatory) patients at post-SOC. BL IL-22 levels differentiated AH patients robustly from the AUD patients (with or without liver injury); and showed corresponding increases stepwise with the stages of ALD. IL-22 was closely associated with progression and injury markers of the liver; and response to the cytokines of pro-inflammatory nature. Pro-inflammatory indicator of IL-17 cell axis, IL-17 showed a strong positive association with MELD, a severity indicator of AH.

Keywords: IL-17; IL-22; alcohol use disorder; alcohol-associated hepatitis; audit.

Figure 1

levels of (A) IL-17 and (B) IL-22 in human plasma (+/- SEM) at baseline (dark bars) and week 4 (lighter bars). Groups were as follows: AUDNLI, AUD no liver injury; AUDLI, AUD with liver injury; NSAH, non-severe alcohol associated hepatitis; SAH, severe alcohol associated hepatitis. IL-17 tended to increase in SAH. IL-22 decreased in AUD from healthy volunteers but increased in SAH. There was no statistical difference between time points within any group. Statistical significance was set as p< 0.05.

Figure 2

IL-22 increased significantly in all AH (combined severe and non-severe) compared to all AUD (combined with and without liver injury) subjects at (A) baseline (p=0.001) and (B) week 4. (C) Baseline IL-22 increased significantly in non-severe AH compared to AUD with liver injury (p=0.001). Statistical significance was set as p< 0.05.

Figure 3

Correlation of IL-22 plasma levels with LTDH in non-severe alcohol associated hepatitis at (A) baseline (p=0.044) and (B) week 4 (p=0.021), and (C) in severe alcohol associated hepatitis at week 4 (p=0.05). Statistical significance was set as p< 0.05.

Figure 4

(A) At baseline, IL-1IL-17 levels correlate with MELD score (p=0.017) in all AH patients (with-in subject). (B) In all AUD patients, IL-1IL-17 decreased significantly from BL to week 4 with standard treatment (p=0.031, within-subject difference). (C) However, in severe AH patients, IL-1IL-17 increased significantly during the 4 weeks of standard care (p=0.006, within-subject difference) suggesting unresolved inflammatory activity (and/or a feedback loop). Statistical significance was set as p< 0.05.

Figure 5

Schema of IL-17 Cell Axis Response and interaction of cytokine pathways in Alcohol-associated Liver Disease. Model for Th-cell associated pathophysiology of alcohol–induced gut dysfunction and pro-inflammatory response leading to liver injury in acute alcohol associated hepatitis.