Low Interleukin-22 Binding Protein Is Associated With High Mortality in Alcoholic Hepatitis and Modulates Interleukin-22 Receptor Expression

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

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.

Relationship between IL-22 and IL-22BP in diabetic cognitive dysfunction

BACKGROUND

CD4 + T helper (Th)22 cells play a regulatory role in autoimmune diseases such as type 1 diabetes mellitus. The Th22-related cytokine interleukin (IL)-22, the expression of which is increased in diabetes mellitus (DM), can act as a neurotrophic factor to protect neurons from apoptosis. Paradoxically, neuronal apoptosis and learning and memory decline occur in DM. In this study, we investigated the relationship between IL-22 and its receptors IL-22Rα1 and IL-22 binding protein (IL-22BP, a soluble inhibitor of IL-22) in diabetic encephalopathy (DE) and the effects of IL-22 on hippocampal neurons, learning and memory.

METHODS

A C57BL/6 mouse model of diabetes was constructed by intraperitoneal injection of streptozotocin. The mice were randomly divided into 4 groups: the control group, diabetes group, diabetes + recombinantIL-22 (rIL-22) group and diabetes + IL-22BP group. The Morris water maze test was used to evaluate learning and memory, the expression of IL-22 was measured by ELISA, and Evans Blue staining was used to evaluate blood-brain barrier permeability. Quantitative reverse transcription polymerase chain reaction (RT-qPCR) was used to measure the mRNA expression of IL-22 and IL-22Rα1 in the hippocampus. The morphology and number of hippocampal neurons were assessed by Nissl staining, and TUNEL staining was used to detect hippocampal neuronal apoptosis. Immunofluorescence was used to analyze IL-22Rα1 expression and localization in hippocampus, and Western blotting was used to evaluate the expression of IL-22, IL-22Rα1, IL-22BP, and the apoptosis related proteins Caspase-3 and C-caspase-3.

RESULTS

Compared with those in the control group, mice in the diabetes group showed cognitive decline; apoptosis of hippocampal neurons; increased expression of hippocampal Caspase-3, C-Caspase-3, IL-22, IL-22Rα1, and IL-22BP; and a decreased IL-22/IL-22BP ratio. Learning and memory were improved, neuronal apoptosis was attenuated, IL-22Rα1 expression and the IL-22/IL-22BP ratio were increased, and caspase-3 and C-caspase-3 expression was decreased in the rIL-22-treated group compared with the diabetes group. IL-22BP treatment aggravated diabetic cognitive dysfunction and pathological alterations in the hippocampus, decreased the IL-22/IL-22BP ratio, and increased the expression of caspase-3 and C-caspase-3 in mice with diabetes.

CONCLUSION

A decrease in the IL-22/IL-22BP ratio plays an important role in diabetic cognitive dysfunction, and rIL-22 can effectively alleviate DE. Herein, we shed light on the interaction between IL-22 and IL-22BP as therapeutic targets for DM.

Down-regulating Interleukin-22/Interleukin-22 binding protein axis promotes inflammation and aggravates diet-induced metabolic disorders

The prevalence of metabolic diseases has become a severe public health problem. Previously, we reported that Interleukin-22 (IL-22) was independently associated with type 2 diabetes mellitus and cardiovascular disease, and could protect endothelial cells from glucose- and lysophosphatidylcholine-induced injury. The activity of IL-22 is strongly regulated by IL-22-binding protein (IL-22BP). The aim of this investigation was to determine the effect of IL-22/IL-22BP axis on glucolipid metabolism. Serum IL-22 and IL-22BP expression in metabolic syndrome (MetS) patients and healthy controls was examined. IL-22BP-knockout (IL-22ra2^-/-) and wild-type (WT) mice were fed with control diet (CTD) and high-fat diet (HFD) for 12 weeks. The IL-22 related pathway expression, the glucolipid metabolism, and inflammatory markers in mice were examined. Serum IL-22 and IL-22BP levels were found significantly increased in MetS patients (p < 0.001). IL-22BP deficiency down-regulated IL-22-related pathway, aggravated glucolipid metabolism disorder, and promoted inflammation in mice. Collectively, this work deepens the understanding of the relationship between IL-22/IL-22BP axis and metabolism disorders, and identified that down-regulation of IL-22/IL-22BP axis promotes metabolic disorders in mice.

Role of IL-22 in intestinal microenvironment and potential targeted therapy through diet

IL-22 is a type 2 receptor cytokine in IL-10 family. IL-22 is usually secreted by innate and adaptive immune cells and takes its effects on non-hematopoietic cells. Through activate STAT3 pathway, IL-22 plays an important role in infection clearance and tissue regeneration, which is critical for barrier integrate and homeostasis. Abnormal activation of IL-22 signal was observed in inflammation diseases, autoimmune diseases, and cancers. We review the recent discoveries about the mechanism and regulation of IL-22 signal pathway from the perspective of intestinal micro-environment. Diet-based IL-22 target therapeutic strategies and their potential clinical significance will also be discussed.

Sex-Dependent Hepatoprotective Role of IL-22 Receptor Signaling in Non-Alcoholic Fatty Liver Disease-Related Fibrosis

BACKGROUND & AIMS

Nonalcoholic fatty liver disease (NAFLD) is a major health problem with complex pathogenesis. Although sex differences in NAFLD pathogenesis have been reported, the mechanisms underlying such differences remain understudied. Interleukin (IL)22 is a pleiotropic cytokine with both protective and/or pathogenic effects during liver injury. IL22 was shown to be hepatoprotective in NAFLD-related liver injury. However, these studies relied primarily on exogenous administration of IL22 and did not examine the sex-dependent effect of IL22. Here, we sought to characterize the role of endogenous IL22-receptor signaling during NAFLD-induced liver injury in males and females.

METHODS

We used immunofluorescence, flow cytometry, histopathologic assessment, and gene expression analysis to examine IL22 production and characterize the intrahepatic immune landscape in human subjects with NAFLD (n = 20; 11 men and 9 women) and in an in vivo Western high-fat diet-induced NAFLD model in IL22RA knock out mice and their wild-type littermates.

RESULTS

Examination of publicly available data sets from 2 cohorts with NAFLD showed increased hepatic IL22 gene expression in females compared with males. Furthermore, our immunofluorescence analysis of liver sections from NAFLD subjects (n = 20) showed increased infiltration of IL22-producing cells in females. Similarly, IL22-producing cells were increased in wild-type female mice with NAFLD and the hepatic IL22/IL22 binding protein messenger RNA ratio correlated with expression of anti-apoptosis genes. The lack of endogenous IL22-receptor signaling (IL22RA knockout) led to exacerbated liver damage, inflammation, apoptosis, and liver fibrosis in female, but not male, mice with NAFLD.

CONCLUSIONS

Our data suggest a sex-dependent hepatoprotective antiapoptotic effect of IL22-receptor signaling during NAFLD-related liver injury in females.

Early loss of T lymphocyte 4-1BB receptor expression is associated with higher short-term mortality in alcoholic hepatitis

Objectives

In alcoholic hepatitis (AH), dysfunctional T lymphocytes may contribute to the high mortality from infections. T lymphocyte activation is governed by the expression of co-stimulatory receptors such as 4-1BB balanced by inhibitory receptors such as Programmed Death receptor 1 (PD-1). 4-1BB expression is unaccounted for in AH, while PD-1 is elevated. We characterized expression of 4-1BB and PD-1 and the associated T lymphocyte functional status in AH and investigated whether these were associated with short-term mortality.

Methods

Thirty-five patients with AH (at diagnosis and days 7 and 90) were compared with healthy controls (HC). Spontaneous and in vitro stimulated receptor expression were quantified by flow cytometry, and plasma proteins by ELISA.

Results

At diagnosis, the patients showed increased stimulated 4-1BB responses of CD4⁺ T lymphocytes. Also, the frequencies of PD-1⁺ T lymphocytes both with and without co-expressed 4-1BB were increased. Further, interferon-gamma was predominantly produced in T lymphocytes co-expressing 4-1BB. A decrease in the frequency of spontaneous 4-1BB⁺ T lymphocytes and an increase in soluble 4-1BB during the first week after diagnosis were associated with higher mortality at day 90 in AH. PD-1 expression showed no systematic dynamics related to mortality.

Conclusions

We found an increased stimulated 4-1BB response of T lymphocytes in AH and early loss of these lymphocytes was associated with a higher short-term mortality. This suggests a role of T lymphocyte 4-1BB expression in the progression of AH.

The good and the bad about separation anxiety: roles of IL-22 and IL-22BP in liver pathologies

The human liver fulfills several vital tasks daily and possesses an impressive ability to self-regenerate. However, the capacity of this self-healing process can be exhausted by a variety of different liver diseases, such as alcoholic liver damage, viral hepatitis, or hepatocellular carcinoma. Over time, all these diseases generally lead to progressive liver failure that can become fatal if left untreated. Thus, a great effort has been directed towards the development of innovative therapies. The most recently discovered therapies often involve modifying the patient's immune system to enhance a beneficial immune response. Current data suggest that, among others, the cytokine IL-22 might be a promising therapeutical candidate. IL-22 and its endogenous antagonist, IL-22BP, have been under thorough scientific investigation for nearly 20 years. While IL-22 is mainly produced by TH22 cells, ILC3s, NKT cells, or γδ T cells, sources of IL-22BP include dendritic cells, eosinophils, and CD4+ cells. In many settings, IL-22 was shown to promote regenerative potential and, thus, could protect tissues from pathogens and damage. However, the effects of IL-22 during carcinogenesis are more ambiguous and depend on the tumor entity and microenvironment. In line with its capabilities of neutralizing IL-22 in vivo, IL-22BP possesses often, but not always, an inverse expression pattern compared to its ligand. In this comprehensive review, we will summarize past and current findings regarding the roles of IL-22 and IL-22BP in liver diseases with a particular focus on the leading causes of advanced liver failure, namely, liver infections, liver damage, and liver malignancies.

Diminished Non-Classical Monocytes in the Blood Associate with Disease Severity in Alcoholic Hepatitis

Objective

Alcoholic hepatitis (AH) holds a high mortality, and vast macrophage infiltration of the liver is involved in the progressive liver injury. No efficient medical treatment exists, and macrophages may be a future treatment target. Here, we examine associations between non-classical monocyte subsets and cell surface markers of migration with disease activity in patients with severe AH.

Methods

We analyzed samples from two cohorts of patients with AH. Cohort 1 included 15 AH patients, followed for 30 days, and 8 healthy controls (HCs). Cohort 2 included 23 AH patients, followed for 90 days, and 9 HCs. Peripheral blood mononuclear cells (PBMCs) from both cohorts were analyzed by flow cytometry. Liver biopsies from cohort 2 were analyzed by RNA sequencing.

Results

Circulating non-classical monocytes in all but absent in patients with AH compared to HC in both cohorts (both p<0.0001). The frequency of non-classical monocytes was significantly associated with Maddrey’s discriminant function (mDF) (r=−0.79, p=0.0008, cohort 1), Child–Pugh score (CP) (r=−0.56, p=0.03, cohort 1), Model for End-Stage Liver Disease (MELD) (r=−0.54, p=0.02, cohort 2) and C-reactive protein (CRP) (r=−0.51, p=0.027, cohort 2). The surface expression of CD11b was increased on non-classical monocytes in patients with AH compared to HC (p<0.0001) (cohort 1). The mRNA expression of CD11b was increased in liver biopsies in patients with AH compared to HC (cohort 2) (p<0.0001).

Conclusion

In this study, we describe an almost complete depletion of circulating non-classical monocytes in the blood in two independent cohorts of patients with AH, which may be associated with a possible harmful recruitment of these cells to the liver. These results contribute to a better understanding of the disease, which hopefully can lead to therapies that target the acute inflammatory response leading to severe AH.