Redefining IL11 as a regeneration-limiting hepatotoxin and therapeutic target in acetaminophen-induced liver injury

Deficiency of ASGR1 promotes liver injury by increasing GP73-mediated hepatic endoplasmic reticulum stress

Liver injury is a core pathological process in the majority of liver diseases, yet the genetic factors predisposing individuals to its initiation and progression remain poorly understood. Here we show that asialoglycoprotein receptor 1 (ASGR1), a lectin specifically expressed in the liver, is downregulated in patients with liver fibrosis or cirrhosis and male mice with liver injury. ASGR1 deficiency exacerbates while its overexpression mitigates acetaminophen-induced acute and CCl4-induced chronic liver injuries in male mice. Mechanistically, ASGR1 binds to an endoplasmic reticulum stress mediator GP73 and facilitates its lysosomal degradation. ASGR1 depletion increases circulating GP73 levels and promotes the interaction between GP73 and BIP to activate endoplasmic reticulum stress, leading to liver injury. Neutralization of GP73 not only attenuates ASGR1 deficiency-induced liver injuries but also improves survival in mice received a lethal dose of acetaminophen. Collectively, these findings identify ASGR1 as a potential genetic determinant of susceptibility to liver injury and propose it as a therapeutic target for the treatment of liver injury.

S-nitrosylation attenuates pregnane X receptor hyperactivity and acetaminophen-induced liver injury

Drug-induced liver injury (DILI), especially acetaminophen overdose, is the leading cause of acute liver failure. Pregnane X receptor (PXR) is a nuclear receptor and the master regulator of drug metabolism. Aberrant activation of PXR plays a pathogenic role in the acetaminophen hepatotoxicity. Here, we aimed to examine the S-nitrosylation of PXR (SNO-PXR) in response to acetaminophen. We found that PXR was S-nitrosylated in hepatocytes and the mouse livers after exposure to acetaminophen or S-nitrosoglutathione (GSNO). Mass spectrometry and site-directed mutagenesis identified the cysteine 307 as the primary residue for S-nitrosylation (SNO) modification. In hepatocytes, SNO suppressed both agonist-induced (rifampicin and SR12813) and constitutively active PXR (VP-PXR, a human PXR fused to the minimal transactivator domain of the herpes virus transcription factor VP16) activations. Furthermore, in acetaminophen-overdosed mouse livers, PXR protein was decreased at the centrilobular regions overlapping with increased SNO. In PXR-/- mice, replenishing the livers with the SNO-deficient PXR significantly aggravated hepatic necrosis, increased HMGB1 release, and exacerbated liver injury and inflammation. Particularly, we demonstrated that S-nitrosoglutathione reductase (GSNOR) inhibitor N6022 promoted hepatoprotection by increasing the levels of SNO-PXR. In conclusion, PXR is posttranslationally modified by SNO in hepatocytes in response to acetaminophen. This modification mitigated the acetaminophen-induced PXR hyperactivity. It may serve as a target for therapeutical intervention.

Oral magnesium prevents acetaminophen-induced acute liver injury by modulating microbial metabolism

Acetaminophen overuse is a common cause of acute liver failure (ALF). During ALF, toxins are metabolized by enzymes such as CYP2E1 and transformed into reactive species, leading to oxidative damage and liver failure. Here, we found that oral magnesium (Mg) alleviated acetaminophen-induced ALF through metabolic changes in gut microbiota that inhibit CYP2E1. The gut microbiota from Mg-supplemented humans prevented acetaminophen-induced ALF in mice. Mg exposure modulated Bifidobacterium metabolism and enriched indole-3-carboxylic acid (I3C) levels. Formate C-acetyltransferase (pflB) was identified as a key Bifidobacterium enzyme involved in I3C generation. Accordingly, a Bifidobacterium pflB knockout showed diminished I3C generation and reduced the beneficial effects of Mg. Conversely, treatment with I3C or an engineered bacteria overexpressing Bifidobacterium pflB protected against ALF. Mechanistically, I3C bound and inactivated CYP2E1, thus suppressing formation of harmful reactive intermediates and diminishing hepatocyte oxidative damage. These findings highlight how interactions between Mg and gut microbiota may help combat ALF.

Estrogen receptor-related receptor (Esrra) induces ribosomal protein Rplp1-mediated adaptive hepatic translation during prolonged starvation

Protein translation is an energy-intensive ribosome-driven process that is reduced during nutrient scarcity to conserve cellular resources. During prolonged starvation, cells selectively translate specific proteins to enhance their survival (adaptive translation); however, this process is poorly understood. Accordingly, we analyzed protein translation and mRNA transcription by multiple methods in vitro and in vivo to investigate adaptive hepatic translation during starvation. While acute starvation suppressed protein translation in general, proteomic analysis showed that prolonged starvation selectively induced translation of lysosome and autolysosome proteins. Significantly, the expression of the orphan nuclear receptor, estrogen-related receptor alpha (Esrra) increased during prolonged starvation and served as a master regulator of this adaptive translation by transcriptionally stimulating 60S acidic ribosomal protein P1 (Rplp1) gene expression. Overexpression or siRNA knockdown of Esrra expression in vitro or in vivo led to parallel changes in Rplp1 gene expression, lysosome/autophagy protein translation, and autophagy. Remarkably, we have found that Esrra had dual functions by not only regulating transcription but also controling adaptive translation via the Esrra/Rplp1/lysosome/autophagy pathway during prolonged starvation.

Understanding interleukin 11 as a disease gene and therapeutic target

Interleukin 11 (IL11) is an elusive member of the IL6 family of cytokines. While initially thought to be a haematopoietic and cytoprotective factor, more recent data show instead that IL11 is redundant for haematopoiesis and toxic. In this review, the reasons that led to the original misunderstandings of IL11 biology, which are now understandable, are explained with particular attention on the use of recombinant human IL11 in mice and humans. Following tissue injury, as part of an evolutionary ancient homeostatic response, IL11 is secreted from damaged mammalian cells to signal via JAK/STAT3, ERK/P90RSK, LKB1/mTOR and GSK3β/SNAI1 in autocrine and paracrine. This activates a program of mesenchymal transition of epithelial, stromal, and endothelial cells to cause inflammation, fibrosis, and stalled endogenous tissue repair, leading to organ failure. The role of IL11 signalling in cell- and organ-specific pathobiology is described, the large unknowns about IL11 biology are discussed and the promise of targeting IL11 signalling as a therapeutic approach is reviewed.

Interleukin-11 and its eminent role in tissue fibrosis: a possible therapeutic target

Interleukin-11 is a cytokine from the IL-6 family of cytokines that includes IL-6 and oncostatin-M. Initially described for its role in platelet generation, it is now appreciated that this cytokine has multiple functions. Recently it has been found that IL-11 is critical in fibrosis in multiple different organ systems and systemically as in the autoimmune disease systemic sclerosis. Animal models of fibrosis have determined that animals with IL-11 receptor deletions have retarded fibrosis and that in wild-type animals IL-11 is found at the organ of fibrosis. Recent evidence suggests that IL-11 may be a master regulator of fibrosis regardless of end target organ. With the development of neutralizing antibodies targeting the cytokine in pre-clinical models this could be a possible therapeutic, in a disease in which no specific therapies exist. This review appraises the evidence of the role of IL-11 in tissue fibrosis, its signalling properties, and therapeutic targeting. The review ends with an appraisal of indications for which IL-11 modulation is targeted.

Glutaredoxin-1 alleviates acetaminophen-induced liver injury by decreasing its toxic metabolites

Excessive N-acetyl-p-benzoquinone imine (NAPQI) formation is a starting event that triggers oxidative stress and subsequent hepatocyte necrosis in acetaminophen (APAP) overdose caused acute liver failure (ALF). S-glutathionylation is a reversible redox post-translational modification and a prospective mechanism of APAP hepatotoxicity. Glutaredoxin-1 (Glrx1), a glutathione-specific thioltransferase, is a primary enzyme to catalyze deglutathionylation. The objective of this study was to explored whether and how Glrx1 is associated with the development of ALF induced by APAP. The Glrx1 knockout mice (Glrx1-/-) and liver-specific overexpression of Glrx1 (AAV8-Glrx1) mice were produced and underwent APAP-induced ALF. Pirfenidone (PFD), a potential inducer of Glrx1, was administrated preceding APAP to assess its protective effects. Our results revealed that the hepatic total protein S-glutathionylation (PSSG) increased and the Glrx1 level reduced in mice after APAP toxicity. Glrx1-/- mice were more sensitive to APAP overdose, with higher oxidative stress and more toxic metabolites of APAP. This was attributed to Glrx1 deficiency increasing the total hepatic PSSG and the S-glutathionylation of cytochrome p450 3a11 (Cyp3a11), which likely increased the activity of Cyp3a11. Conversely, AAV8-Glrx1 mice were defended against liver damage caused by APAP overdose by inhibiting the S-glutathionylation and activity of Cyp3a11, which reduced the toxic metabolites of APAP and oxidative stress. PFD precede administration upregulated Glrx1 expression and alleviated APAP-induced ALF by decreasing oxidative stress. We have identified the function of Glrx1 mediated PSSG in liver injury caused by APAP overdose. Increasing Glrx1 expression may be investigated for the medical treatment of APAP-caused hepatic injury.

Targeting IL-6 trans-signalling: past, present and future prospects

Interleukin-6 (IL-6) is a key immunomodulatory cytokine that affects the pathogenesis of diverse diseases, including autoimmune diseases, chronic inflammatory conditions and cancer. Classical IL-6 signalling involves the binding of IL-6 to the membrane-bound IL-6 receptor α-subunit (hereafter termed 'mIL-6R') and glycoprotein 130 (gp130) signal-transducing subunit. By contrast, in IL-6 trans-signalling, complexes of IL-6 and the soluble form of IL-6 receptor (sIL-6R) signal via membrane-bound gp130. A third mode of IL-6 signalling - known as cluster signalling - involves preformed complexes of membrane-bound IL-6-mIL-6R on one cell activating gp130 subunits on target cells. Antibodies and small molecules have been developed that block all three forms of IL-6 signalling, but in the past decade, IL-6 trans-signalling has emerged as the predominant pathway by which IL-6 promotes disease pathogenesis. The first selective inhibitor of IL-6 trans-signalling, sgp130, has shown therapeutic potential in various preclinical models of disease and olamkicept, a sgp130Fc variant, had promising results in phase II clinical studies for inflammatory bowel disease. Technological developments have already led to next-generation sgp130 variants with increased affinity and selectivity towards IL-6 trans-signalling, along with indirect strategies to block IL-6 trans-signalling. Here, we summarize our current understanding of the biological outcomes of IL-6-mediated signalling and the potential for targeting this pathway in the clinic.

Cardiomyocyte-Restricted Expression of IL11 Causes Cardiac Fibrosis, Inflammation, and Dysfunction

Cardiac fibrosis is a common pathological process in heart disease, representing a therapeutic target. Transforming growth factor β (TGFβ) is the canonical driver of cardiac fibrosis and was recently shown to be dependent on interleukin 11 (IL11) for its profibrotic effects in fibroblasts. In the opposite direction, recombinant human IL11 has been reported as anti-fibrotic and anti-inflammatory in the mouse heart. In this study, we determined the effects of IL11 expression in cardiomyocytes on cardiac pathobiology and function. We used the Cre-loxP system to generate a tamoxifen-inducible mouse with cardiomyocyte-restricted murine Il11 expression. Using protein assays, bulk RNA-sequencing, and in vivo imaging, we analyzed the effects of IL11 on myocardial fibrosis, inflammation, and cardiac function, challenging previous reports suggesting the cardioprotective potential of IL11. TGFβ stimulation of cardiomyocytes caused Il11 upregulation. Compared to wild-type controls, Il11-expressing hearts demonstrated severe cardiac fibrosis and inflammation that was associated with the upregulation of cytokines, chemokines, complement factors, and increased inflammatory cells. IL11 expression also activated a program of endothelial-to-mesenchymal transition and resulted in left ventricular dysfunction. Our data define species-matched IL11 as strongly profibrotic and proinflammatory when secreted from cardiomyocytes and further establish IL11 as a disease factor.

Role of Interleukin-6 Family Cytokines in Organ Fibrosis

Background

Organ fibrosis remains an important cause of high incidence rate and mortality worldwide. The prominent role of interleukin-6 (IL-6) family members represented by IL-6 in inflammation has been extensively studied, and drugs targeting IL-6 have been used clinically. Because of the close relationship between inflammation and fibrosis, researches on the role of IL-6 family members in organ fibrosis are also gradually emerging.

Summary

In this review, we systematically reviewed the role of IL-6 family members in fibrosis and their possible mechanisms. We listed the role of IL-6 family members in organ fibrosis and drew two diagrams to illustrate the downstream signal transductions of IL-6 family members. We also summarized the effect of some IL-6 family members' antagonists in a table.

Key Messages

Fibrosis contributes to organ structure damage, organ dysfunction, and eventually organ failure. Although IL-6 family cytokines have similar downstream signal pathways, different members play various roles in an organ-specific manner which might be partly due to their different target cell populations. The pathogenic role of individual member in various diseases needs to be deciphered carefully.

Celastrol-loaded biomimetic nanodrug ameliorates APAP-induced liver injury through modulating macrophage polarization

Drug-induced liver injury (DILI) is a major concern in clinical treatment as well as postmarketing surveillance, showing an urgent requirement for the development of protective medications. Celastrol (Cel), a highly active natural product extracted from the roots of Tripterygium wilfordii, has a potential liver protective activity due to its antioxidant and anti-inflammatory effects. However, the further application of Cel to DILI remains a challenge because of its short half-life, low solubility, and toxic side effects. Herein, we developed a Cel-loaded biomimetic nanodrug based on erythrocyte membrane vesicles (EMV) for protecting the liver from acetaminophen (APAP)-induced liver injury. The Cel-loaded EMV (C-EMV) with lower cytotoxicity had a well-sustained release effect and exhibited excellent ability for liver accumulation under physiological and pathological conditions. By suppressing the inflammatory response of pro-inflammatory macrophage M1 polarization while stimulating anti-inflammatory macrophage M2 polarization, C-EMV could significantly alleviate the primary pathological manifestations related to liver injury, including aberrant elevation of biochemical indicators, histopathological alterations, neutrophil infiltration as well as hepatocyte DNA fragmentation. The macrophage depletion experiment further demonstrated that the protective effect of C-EMV on APAP-induced liver injury appeared to be dependent on hepatic macrophages. Therefore, C-EMV as a biomimetic nanodrug exhibits great potential for attenuating the progress of DILI, providing a new approach to protecting the liver from DILI as well as other liver inflammatory diseases through a targeted nanodelivery system. KEY MESSAGES: EMV biomimetic nanocarrier has good monodispersity and sustained-release property. EMV biomimetic nanocarrier displays excellent liver-targeting capability under physiological and pathological conditions. C-EMV biomimetic nanodrug with lower cytotoxicity regulates macrophage polarization in vitro and in vivo. C-EMV biomimetic nanodrug can significantly alleviate APAP-induced liver injury. The protective effect of C-EMV on APAP-induced liver injury is dependent on hepatic macrophages.

IL11 (Interleukin-11) Causes Emphysematous Lung Disease in a Mouse Model of Marfan Syndrome

BACKGROUND

Marfan Syndrome (MFS) is an inherited connective tissue disorder caused by mutations in the FBN1 (fibrillin-1) gene. Lung abnormalities are common in MFS, but their pathogenesis is poorly understood. IL11 (interleukin-11) causes aortic disease in a mouse model of MFS and was studied here in the lung.

METHODS

We examined histological and molecular phenotypes in the lungs of Fbn1C1041G/+ mice (mouse model of Marfan Syndrome [mMFS]), an established mouse model of MFS. To identify IL11-expressing cells, we used immunohistochemistry on lungs of 4- and 16-week-old Fbn1C1041G/+:Il11EGFP/+ reporter mice. We studied the effects of IL11 inhibition by RT-qPCR, immunoblots and histopathology in lungs from genetic or pharmacologic models: (1) 16-week-old IL11 receptor (IL11RA) knockout mMFS mice (Fbn1C1041G/+:Il11ra1-/- mice) and (2) in mMFS mice administered IgG control or interleukin-11 receptor antibodies twice weekly from 4 to 24 weeks of age.

RESULTS

mMFS lungs showed progressive loss and enlargement of distal airspaces associated with increased proinflammatory and profibrotic gene expression as well as matrix metalloproteinases 2, 9, and 12. IL11 was increased in mMFS lungs and localized to smooth muscle and endothelial cells in young mMFS mice in the Fbn1C1041G/+:Il11EGFP/+ reporter strain and in fibroblasts, in older mice. In mMFS mice, genetic (Fbn1C1041G/+:Il11ra1-/-) or pharmacologic (anti-interleukin-11 receptor) inhibition of IL11 signaling reduced lung emphysema, fibrosis, and inflammation. This protective effect was associated with reduced pathogenic ERK1/2 signaling and lower metalloproteinase 2, 9, and 12 expression.

CONCLUSIONS

IL11 causes lung disease in mMFS. This reveals a shared IL11-driven disease mechanism in lung and aorta in MFS and suggests inhibition of IL11 signaling as a holistic approach for treating multiorgan morbidity in MFS.

Interleukin 11 confers resistance to dextran sulfate sodium-induced colitis in mice

Intestinal homeostasis is tightly regulated by epithelial cells, leukocytes, and stromal cells, and its dysregulation is associated with inflammatory bowel diseases. Interleukin (IL)-11, a member of the IL-6 family of cytokines, is produced by inflammatory fibroblasts during acute colitis. However, the role of IL-11 in the development of colitis is still unclear. Herein, we showed that IL-11 ameliorated DSS-induced acute colitis in mouse models. We found that deletion of Il11ra1 or Il11 rendered mice highly susceptible to DSS-induced colitis compared to the respective control mice. The number of apoptotic epithelial cells was increased in DSS-treated Il11ra1- or Il11-deficient mice. Moreover, we showed that IL-11 production was regulated by reactive oxygen species (ROS) produced by lysozyme M-positive myeloid cells. These findings indicate that fibroblast-produced IL-11 plays an important role in protecting the mucosal epithelium in acute colitis. Myeloid cell-derived ROS contribute to the attenuation of colitis through the production of IL-11.

Interleukin-11 Is Elevated in Patients with Atrial Fibrillation, Correlates with Serum Fibrosis Markers, and Represents a Therapeutic Target for Atrial Fibrosis

INTRODUCTION

Inflammatory cytokines are closely associated with developing cardiac fibrosis. This research aimed to explore the significant role of IL-11 in atrial fibrosis progression and potential therapeutic targets.

METHODS

207 AF patients and 160 healthy subjects were included in the case-control study. Blood samples were analyzed for the level of IL-11 by enzyme-linked immunosorbent assay (ELISA). Angiotensin II (Ang II)-treated fibrosis mouse models were generated, and expression of IL-11 mRNA and protein was detected by RT-qPCR and Western blot. IL-11 antagonist was used to evaluating atrial fibrosis-related markers.

RESULTS

The persistent atrial fibrillation patients (n = 76) had significantly larger left atrial size, higher serum levels of hypertrophic protein BNP, proinflammatory cytokine high-sensitivity C-reactive protein (hs-CRP), and interleukin-6 (IL-6) compared to paroxysmal atrial fibrillation patients (n = 131), and healthy subjects (all p < 0.05). Pearson correlation analysis revealed significant positive correlation between serum IL-11 and cardiac fibrosis markers BNP (r = 0.394, p < 0.001), CTX-I (r = 0.418, p < 0.001), PICP (r = 0.306, p < 0.001), PIIINP (r = 0.335, p < 0.001), and TGF-β1 (r = 0.273, p < 0.001). In the fibrosis mouse model, Ang II infusion significantly upregulated IL-11 mRNA and protein expression in the left atrium of mice (p < 0.05), as well as staining intensity of Masson trichrome, the intensity of α-SMA, and it increased mRNA expression of collagen I and III in atrial tissue. IL-11 antagonist treatment significantly attenuated Masson trichrome, number of α-SMA-positive myofibroblasts in atrial tissue. Also, it significantly reduced the p-ERK1/2 in atrial tissue of mice infused with Ang II (p < 0.05).

CONCLUSIONS

IL-11 is upregulated in the serum of AF patients, and IL-11 inhibitor significantly inhibited Ang II-induced atrial fibrosis, a key pathological feature of AF. Therefore, IL-11 could be a potential therapeutic target for AF.

Interleukin-11 drives human and mouse alcohol-related liver disease

OBJECTIVE

Alcoholic hepatitis (AH) reflects acute exacerbation of alcoholic liver disease (ALD) and is a growing healthcare burden worldwide. Interleukin-11 (IL-11) is a profibrotic, proinflammatory cytokine with increasingly recognised toxicities in parenchymal and epithelial cells. We explored IL-11 serum levels and their prognostic value in patients suffering from AH and cirrhosis of various aetiology and experimental ALD.

DESIGN

IL-11 serum concentration and tissue expression was determined in a cohort comprising 50 patients with AH, 110 patients with cirrhosis and 19 healthy volunteers. Findings were replicated in an independent patient cohort (n=186). Primary human hepatocytes exposed to ethanol were studied in vitro. Ethanol-fed wildtype mice were treated with a neutralising murine IL-11 receptor-antibody (anti-IL11RA) and examined for severity signs and markers of ALD.

RESULTS

IL-11 serum concentration and hepatic expression increased with severity of liver disease, mostly pronounced in AH. In a multivariate Cox-regression, a serum level above 6.4 pg/mL was a model of end-stage liver disease independent risk factor for transplant-free survival in patients with compensated and decompensated cirrhosis. In mice, severity of alcohol-induced liver inflammation correlated with enhanced hepatic IL-11 and IL11RA expression. In vitro and in vivo, anti-IL11RA reduced pathogenic signalling pathways (extracellular signal-regulated kinases, c-Jun N-terminal kinase, NADPH oxidase 4) and protected hepatocytes and murine livers from ethanol-induced inflammation and injury.

CONCLUSION

Pathogenic IL-11 signalling in hepatocytes plays a crucial role in the pathogenesis of ALD and could serve as an independent prognostic factor for transplant-free survival. Blocking IL-11 signalling might be a therapeutic option in human ALD, particularly AH.

Targeting endogenous kidney regeneration using anti-IL11 therapy in acute and chronic models of kidney disease

The kidney has large regenerative capacity, but this is compromised when kidney damage is excessive and renal tubular epithelial cells (TECs) undergo SNAI1-driven growth arrest. Here we investigate the role of IL11 in TECs, kidney injury and renal repair. IL11 stimulation of TECs induces ERK- and p90RSK-mediated GSK3β inactivation, SNAI1 upregulation and pro-inflammatory gene expression. Mice with acute kidney injury upregulate IL11 in TECs leading to SNAI1 expression and kidney dysfunction, which is not seen in Il11 deleted mice or in mice administered a neutralizing IL11 antibody in either preemptive or treatment modes. In acute kidney injury, anti-TGFβ reduces renal fibrosis but exacerbates inflammation and tubule damage whereas anti-IL11 reduces all pathologies. Mice with TEC-specific deletion of Il11ra1 have reduced pathogenic signaling and are protected from renal injury-induced inflammation, fibrosis, and failure. In a model of chronic kidney disease, anti-IL11 therapy promotes TEC proliferation and parenchymal regeneration, reverses fibroinflammation and restores renal mass and function. These data highlight IL11-induced mesenchymal transition of injured TECs as an important renal pathology and suggest IL11 as a therapeutic target for restoring stalled endogenous regeneration in the diseased kidney.

The immunological mechanisms and therapeutic potential in drug-induced liver injury: lessons learned from acetaminophen hepatotoxicity

Acute liver failure caused by drug overdose is a significant clinical problem in developed countries. Acetaminophen (APAP), a widely used analgesic and antipyretic drug, but its overdose can cause acute liver failure. In addition to APAP-induced direct hepatotoxicity, the intracellular signaling mechanisms of APAP-induced liver injury (AILI) including metabolic activation, mitochondrial oxidant stress and proinflammatory response further affect progression and severity of AILI. Liver inflammation is a result of multiple interactions of cell death molecules, immune cell-derived cytokines and chemokines, as well as damaged cell-released signals which orchestrate hepatic immune cell infiltration. The immunoregulatory interplay of these inflammatory mediators and switching of immune responses during AILI lead to different fate of liver pathology. Thus, better understanding the complex interplay of immune cell subsets in experimental models and defining their functional involvement in disease progression are essential to identify novel therapeutic targets for the treatment of AILI. Here, this present review aims to systematically elaborate on the underlying immunological mechanisms of AILI, its relevance to immune cells and their effector molecules, and briefly discuss great therapeutic potential based on inflammatory mediators.

IL11 stimulates ERK/P90RSK to inhibit LKB1/AMPK and activate mTOR initiating a mesenchymal program in stromal, epithelial, and cancer cells

IL11 initiates fibroblast activation but also causes epithelial cell dysfunction. The mechanisms underlying these processes are not known. We report that IL11-stimulated ERK/P90RSK activity causes the phosphorylation of LKB1 at S325 and S428, leading to its inactivation. This inhibits AMPK and activates mTOR across cell types. In stromal cells, IL11-stimulated ERK activity inhibits LKB1/AMPK which is associated with mTOR activation, ⍺SMA expression, and myofibroblast transformation. In hepatocytes and epithelial cells, IL11/ERK activity inhibits LKB1/AMPK leading to mTOR activation, SNAI1 expression, and cell dysfunction. Across cells, IL11-induced phenotypes were inhibited by metformin stimulated AMPK activation. In mice, genetic or pharmacologic manipulation of IL11 activity revealed a critical role of IL11/ERK signaling for LKB1/AMPK inhibition and mTOR activation in fatty liver disease. These data identify the IL11/mTOR axis as a signaling commonality in stromal, epithelial, and cancer cells and reveal a shared IL11-driven mesenchymal program across cell types.

IL11 Stimulates IL33 Expression and Proinflammatory Fibroblast Activation across Tissues

Interleukin 11 (IL11) is upregulated in inflammatory conditions, where it is mostly believed to have anti-inflammatory activity. However, recent studies suggest instead that IL11 promotes inflammation by activating fibroblasts. Here, we assessed whether IL11 is pro- or anti-inflammatory in fibroblasts. Primary cultures of human kidney, lung or skin fibroblasts were stimulated with IL11 that resulted in the transient phosphorylation of signal transducer and activator of transcription 3 (STAT3) and the sustained activation of extracellular signal-regulated protein kinases (ERK). RNA sequencing over a time course of IL11 stimulation revealed a robust but short-lived transcriptional response that was enriched for gene set hallmarks of inflammation and characterized by the upregulation of SERPINB2, TNFRSF18, Interleukin 33 (IL33), CCL20, IL1RL1, CXCL3/5/8, ICAM1 and IL11 itself. IL33 was the most upregulated signaling factor (38-fold, p = 9.8 × 10^-5), and IL1RL1, its cognate receptor, was similarly increased (18-fold, p = 1.1 × 10^-34). In proteomic studies, IL11 triggered a proinflammatory secretome with the notable upregulation of IL8, IL6, MCP1, CCL20 and CXCL1/5/6, which are important chemotaxins for neutrophils, monocytes, and lymphocytes. IL11 induced IL33 expression across fibroblast types, and the inhibition of STAT3 but not of MEK/ERK prevented this. These data establish IL11 as pro-inflammatory with specific importance for priming the IL33 alarmin response in inflammatory fibroblasts across tissues.

Ultrasmall Ruthenium Nanoparticles with Boosted Antioxidant Activity Upregulate Regulatory T Cells for Highly Efficient Liver Injury Therapy

Nanozymes exhibiting antioxidant activity are beneficial for the treatment of oxidative stress-associated diseases. Ruthenium nanoparticles (RuNPs) with multiple enzyme-like activities have attracted growing attention, but the relatively low antioxidant enzyme-like activities hinder their practical biomedical applications. Here, a size regulation strategy is presented to significantly boost the antioxidant enzyme-like activities of RuNPs. It is found that as the size of RuNPs decreases to ≈2.0 nm (sRuNP), the surface-oxidized Ru atoms become dominant, thus possessing an unprecedentedly boosted antioxidant activity as compared to medium-sized (≈3.9 nm) or large-sized counterparts (≈5.9 nm) that are mainly composed of surface metallic Ru atoms. Notably, based on their antioxidant enzyme-like activities and ultrasmall size, sRuNP can not only sustainably ameliorate oxidative stress but also upregulate regulatory T cells in late-stage acetaminophen (APAP)-induced liver injury (ALI). Consequently, sRuNPs perform highly efficient therapeutic efficiency on ALI mice even when treated at 6 h after APAP intoxication. This strategy is insightful for tuning the catalytic performances of nanozymes for their extensive biomedical applications.

Hepatocyte Specific gp130 Signalling Underlies APAP Induced Liver Injury

N-acetyl-p-aminophenol (APAP)-induced liver damage is associated with upregulation of Interleukin-11 (IL11), which is thought to stimulate IL6ST (gp130)-mediated STAT3 activity in hepatocytes, as a compensatory response. However, recent studies have found IL11/IL11RA/gp130 signaling to be hepatotoxic. To investigate further the role of IL11 and gp130 in APAP liver injury, we generated two new mouse strains with conditional knockout (CKO) of either Il11 (CKO^Il11) or gp130 (CKO^gp130) in adult hepatocytes. Following APAP, as compared to controls, CKO^gp130 mice had lesser liver damage with lower serum Alanine Transaminase (ALT) and Aspartate Aminotransferase (AST), greatly reduced serum IL11 levels (90% lower), and lesser centrilobular necrosis. Livers from APAP-injured CKO^gp130 mice had lesser ERK, JNK, NOX4 activation and increased markers of regeneration (PCNA, Cyclin D1, Ki67). Experiments were repeated in CKO^Il11 mice that, as compared to wild-type mice, had lower APAP-induced ALT/AST, reduced centrilobular necrosis and undetectable IL11 in serum. As seen with CKO^gp130 mice, APAP-treated CKO^Il11 mice had lesser ERK/JNK/NOX4 activation and greater features of regeneration. Both CKO^gp130 and CKO^Il11 mice had normal APAP metabolism. After APAP, CKO^gp130 and CKO^Il11 mice had reduced Il6, Ccl2, Ccl5, Il1β, and Tnfα expression. These studies exclude IL11 upregulation as compensatory and establish autocrine, self-amplifying, gp130-dependent IL11 secretion from damaged hepatocytes as toxic and anti-regenerative.

IL11 Activates Pancreatic Stellate Cells and Causes Pancreatic Inflammation, Fibrosis and Atrophy in a Mouse Model of Pancreatitis

Interleukin-11 (IL11) is important for fibrosis and inflammation, but its role in the pancreas is unclear. In pancreatitis, fibrosis, inflammation and organ dysfunction are associated with pancreatic stellate cell (PSC)-to-myofibroblast transformation. Here, we show that IL11 stimulation of PSCs, which specifically express IL11RA in the pancreas, results in transient STAT3 phosphorylation, sustained ERK activation and PSC activation. In contrast, IL6 stimulation of PSCs caused sustained STAT3 phosphorylation but did not result in ERK activation or PSC transformation. Pancreatitis factors, including TGFβ, CTGF and PDGF, induced IL11 secretion from PSCs and a neutralising IL11RA antibody prevented PSC activation by these stimuli. This revealed an important ERK-dependent role for autocrine IL11 activity in PSCs. In mice, IL11 was increased in the pancreas after pancreatic duct ligation, and in humans, IL11 and IL11RA levels were elevated in chronic pancreatitis. Following pancreatic duct ligation, administration of anti-IL11RA to mice reduced pathologic (ERK, STAT, NF-κB) signalling, pancreatic atrophy, fibrosis and pro-inflammatory cytokine (TNFα, IL6 and IL1β) levels. This is the first description of IL11-mediated activation of PSCs, and the data suggest IL11 as a stromal therapeutic target in pancreatitis.

Inhibition of IL11 Signaling Reduces Aortic Pathology in Murine Marfan Syndrome

BACKGROUND

Marfan syndrome (MFS) is associated with TGF (transforming growth factor) β-stimulated ERK (extracellular signal-regulated kinase) activity in vascular smooth muscle cells (VSMCs), which adopt a mixed synthetic/contractile phenotype. In VSMCs, TGFβ induces IL (interleukin) 11) that stimulates ERK-dependent secretion of collagens and MMPs (matrix metalloproteinases). Here, we examined the role of IL11 in the MFS aorta.

METHODS

We used echocardiography, histology, immunostaining, and biochemical methods to study aortic anatomy, physiology, and molecular endophenotypes in Fbn1^C1041G/+ mice, an established murine model of MFS (mMFS). mMFS mice were crossed to an IL11-tagged EGFP (enhanced green fluorescent protein; Il11^EGFP/+) reporter strain or to a strain deleted for the IL11 receptor (Il11ra1^-/-). In therapeutic studies, mMFS were administered an X209 (neutralizing antibody against IL11RA [IL11 receptor subunit alpha]) or IgG for 20 weeks and imaged longitudinally.

RESULTS

IL11 mRNA and protein were elevated in the aortas of mMFS mice, as compared to controls. mMFS mice crossed to Il11^EGFP/+ mice had increased IL11 expression in VSMCs, notably in the aortic root and ascending aorta. As compared to the mMFS parental strain, double mutant mMFS:Il11ra1^-/- mice had reduced aortic dilatation and exhibited lesser fibrosis, inflammation, elastin breaks, and VSMC loss, which was associated with reduced aortic COL1A1 (collagen type I alpha 1 chain), IL11, MMP2/9, and phospho-ERK expression. To explore therapeutic targeting of IL11 signaling in MFS, we administered either a neutralizing antibody against IL11RA (X209) or an IgG control. After 20 weeks of antibody administration, as compared to IgG, mMFS mice receiving X209 had reduced thoracic and abdominal aortic dilation as well as lesser fibrosis, inflammation, elastin breaks, and VSMC loss. By immunoblotting, X209 was shown to reduce aortic COL1A1, IL11, MMP2/9, and phospho-ERK expression.

CONCLUSIONS

In MFS, IL11 is upregulated in aortic VSMCs to cause ERK-related thoracic aortic dilatation, inflammation, and fibrosis. Therapeutic inhibition of IL11, imminent in clinical trials, might be considered as a new approach in MFS.

A Neutralizing IL-11 Antibody Improves Renal Function and Increases Lifespan in a Mouse Model of Alport Syndrome

BACKGROUND

Alport syndrome is a genetic disorder characterized by a defective glomerular basement membrane, tubulointerstitial fibrosis, inflammation, and progressive renal failure. IL-11 was recently implicated in fibrotic kidney disease but its role in Alport syndrome is unknown Methods: We determined IL-11 expression by molecular analyses and in an Alport syndrome mouse model. We assessed the effects of a neutralizing IL-11 antibody (X203) versus an IgG control in Col4a3-/- mice (lacking the gene encoding a type IV collagen component) on renal tubule damage, function, fibrosis, and inflammation. Effects on lifespan of X203, the IgG control, an angiotensin-converting enzyme inhibitor (ramipril), or ramipril+X203 were also studied.

RESULTS

In Col4a3 mice, as kidney failure advanced, renal IL-11 levels increased and IL-11 expression localized to tubular epithelial cells. The IL-11 receptor IL11RA is expressed in tubular epithelial cells and podocytes and is upregulated in tubular epithelial cells of Col4a3 mice. Administration of X203 reduced albuminuria, improved renal function, and preserved podocyte numbers and levels of key podocyte proteins that are reduced in Col4a3 mice; these effects were accompanied by reduced fibrosis and inflammation, attenuation of epithelial-tomesenchymal transition, and increased expression of regenerative markers. X203 attenuated pathogenic ERK and STAT3 pathways, which were activated in Col4a3 mice. Median lifespan of Col4a3 mice was prolonged 22% by ramapril, 44% with X203, and 99% with amipril+X203.

CONCLUSIONS

In an Alport syndrome mouse model, renal IL-11 is upregulated, and neutralization of IL-11 reduces epithelial-to-mesenchymal transition, fibrosis, and inflammation, while improving renal function. Anti-IL-11 combined with ACE inhibition synergistically extends lifespan. This suggests that a therapeutic approach targeting IL-11 holds promise for progressive kidney disease in Alport syndrome.

CD5L deficiency attenuate acetaminophen-induced liver damage in mice via regulation of JNK and ERK signaling pathway

CD5 molecule like (CD5L), a member of the scavenger receptor cysteine-rich domain superfamily, plays a critical role in immune homeostasis and inflammatory disease. Acetaminophen (APAP) is a safe and effective antipyretic analgesic. However, overdose may cause liver damage or even liver failure. APAP hepatotoxicity is characterized by extensive necrotic cell death and a sterile inflammatory response, in which the role of CD5L remains to be investigated. In this study, we found that the expression of CD5L was increased in the livers of mice after APAP overdose. Furthermore, CD5L deficiency reduced the increase of alanine transaminase (ALT) level, histopathologic lesion area, c-Jun N-terminal kinase (JNK)/extracellular signal-regulated kinase (ERK) phosphorylation level, Transferase-Mediated dUTP Nick End-Labeling positive (TUNEL⁺) cells proportion, vascular endothelial cell permeability and release of inflammatory cytokines induced by excess APAP. Therefore, our findings reveal that CD5L may be a potential therapeutic target for prevention and treatment of APAP-induced liver injury.

Emerging roles for IL-11 in inflammatory diseases

Interleukin-11 (IL-11) is a cytokine that has been strongly implicated in the pathogenesis of fibrotic diseases and solid malignancies. Elevated IL-11 expression is also associated with several non-malignant inflammatory diseases where its function remains less well-characterized. Here, we summarize current literature surrounding the contribution of IL-11 to the pathogenesis of autoimmune inflammatory diseases, including rheumatoid arthritis, multiple sclerosis, diabetes and systemic sclerosis, as well as other chronic inflammatory conditions such as periodontitis, asthma, chronic obstructive pulmonary disease, psoriasis and colitis.

A neutralizing IL-11 antibody reduces vessel hyperplasia in a mouse carotid artery wire injury model

Vascular restenosis remains a major problem in patients with coronary artery disease (CAD) and peripheral artery disease (PAD). Neointimal hyperplasia, defined by post-procedure proliferation and migration of vascular smooth muscle cells (VSMCs) is a key underlying pathology. Here we investigated the role of Interleukin 11 (IL-11) in a mouse model of injury-related plaque development. Apoe^-/- mice were fed a hyperlipidaemic diet and subjected to carotid wire injury of the right carotid. Mice were injected with an anti-IL11 antibody (X203), IgG control antibody or buffer. We performed ultrasound analysis to assess vessel wall thickness and blood velocity. Using histology and immunofluorescence approaches, we determined the effects of IL-11 inhibition on VSMC and macrophages phenotypes and fibrosis. Treatment of mice with carotid wire injury using X203 significantly reduced post-endothelial injury vessel wall thickness, and injury-related plaque, when compared to control. Immunofluorescence staining of the injury-related plaque showed that X203 treatment did not reduce macrophage numbers, but reduced the number of VSMCs and lowered matrix metalloproteinase 2 (MMP2) levels and collagen content in comparison to control. X203 treatment was associated with a significant increase in smooth muscle protein 22α (SM22α) positive cells in injury-related plaque compared to control, suggesting preservation of the contractile VSMC phenotype. Interestingly, X203 also reduced the collagen content of uninjured carotid arteries as compared to IgG, showing an additional effect on hyperlipidemia-induced arterial remodeling in the absence of mechanical injury. Therapeutic inhibition of IL-11 reduced vessel wall thickness, attenuated neointimal hyperplasia, and has favorable effects on vascular remodeling following wire-induced endothelial injury. This suggests IL-11 inhibition as a potential novel therapeutic approach to reduce arterial stenosis following revascularization in CAD and PAD patients.

Molecular Dissection of Pro-Fibrotic IL11 Signaling in Cardiac and Pulmonary Fibroblasts

In fibroblasts, TGFβ1 stimulates IL11 upregulation that leads to an autocrine loop of IL11-dependent pro-fibrotic protein translation. The signaling pathways downstream of IL11, which acts via IL6ST, are contentious with both STAT3 and ERK implicated. Here we dissect IL11 signaling in fibroblasts and study IL11-dependent protein synthesis pathways in the context of approved anti-fibrotic drug mechanisms of action. We show that IL11-induced ERK activation drives fibrogenesis and while STAT3 phosphorylation (pSTAT3) is also seen, this appears unrelated to fibroblast activation. Ironically, recombinant human IL11, which has been used extensively in mouse experiments to infer STAT3 activity downstream of IL11, increases pSTAT3 in Il11ra1 null mouse fibroblasts. Unexpectedly, inhibition of STAT3 was found to induce severe proteotoxic ER stress, generalized fibroblast dysfunction and cell death. In contrast, inhibition of ERK prevented fibroblast activation in the absence of ER stress. IL11 stimulated an axis of ERK/mTOR/P70RSK protein translation and its selectivity for Collagen 1 synthesis was ascribed to an EPRS-regulated, ribosome stalling mechanism. Surprisingly, the anti-fibrotic drug nintedanib caused dose-dependent ER stress and lesser pSTAT3 expression. Pirfenidone had no effect on ER stress whereas anti-IL11 specifically inhibited the ERK/mTOR axis while reducing ER stress. These studies define the translation-specific signaling pathways downstream of IL11, intersect immune and metabolic signaling and reveal unappreciated effects of nintedanib.

The TGF-β/NADPH Oxidases Axis in the Regulation of Liver Cell Biology in Health and Disease

The Transforming Growth Factor-beta (TGF-β) pathway plays essential roles in liver development and homeostasis and become a relevant factor involved in different liver pathologies, particularly fibrosis and cancer. The family of NADPH oxidases (NOXs) has emerged in recent years as targets of the TGF-β pathway mediating many of its effects on hepatocytes, stellate cells and macrophages. This review focuses on how the axis TGF-β/NOXs may regulate the biology of different liver cells and how this influences physiological situations, such as liver regeneration, and pathological circumstances, such as liver fibrosis and cancer. Finally, we discuss whether NOX inhibitors may be considered as potential therapeutic tools in liver diseases.

The pro-regenerative effects of hyperIL6 in drug-induced liver injury are unexpectedly due to competitive inhibition of IL11 signaling

It is generally accepted that IL6-mediated STAT3 signaling in hepatocytes, mediated via glycoprotein 130 (gp130; IL6ST), is beneficial and that the synthetic IL6:IL6ST fusion protein (HyperIL6) promotes liver regeneration. Recently, autocrine IL11 activity that also acts via IL6ST but uses ERK rather than STAT3 to signal, was found to be hepatotoxic. Here we examined whether the beneficial effects of HyperIL6 could reflect unappreciated competitive inhibition of IL11-dependent IL6ST signaling. In human and mouse hepatocytes, HyperIL6 reduced N-acetyl-p-aminophenol (APAP)-induced cell death independent of STAT3 activation and instead, dose-dependently, inhibited IL11-related signaling and toxicities. In mice, expression of HyperIl6 reduced ERK activation and promoted STAT3-independent hepatic regeneration (PCNA, Cyclin D1, Ki67) following administration of either IL11 or APAP. Inhibition of putative intrinsic IL6 trans-signaling had no effect on liver regeneration in mice. Following APAP, mice deleted for Il11 exhibited spontaneous liver repair but HyperIl6, despite robustly activating STAT3, had no effect on liver regeneration in this strain. These data show that synthetic IL6ST binding proteins such as HyperIL6 can have unexpected, on-target effects and suggest IL11, not IL6, as important for liver regeneration.

Comparison of the toxicity of pure compounds and commercial formulations of imidacloprid and acetamiprid on HT-29 cells: Single and mixture exposure

Neonicotinoids, which are widely used worldwide, including in Turkey, are an insecticide group that are synthetic derivatives of nicotine. Recently, they have attracted attention due to their toxic effects on non-target organisms, especially bees. Numerous studies have shown that neonicotinoids have been found in detectable levels in the environment and cause various undesirable effects on living organisms, including humans and other mammals. In this study, the possible toxic effects of imidacloprid and acetamiprid, commonly used neonicotinoids, are investigated by their pure forms and commercial formulations on HT-29 cells with individual and combined exposures. According to our results, imidacloprid and acetamiprid induced cytotoxicity by caspase-mediated apoptosis, mitochondrial membrane depolarization, DNA damage, and oxidative stress under these experimental conditions. It is worth mentioning low doses of DNA damage, mixture exposure causes toxic effects at lower concentrations than individual exposure, and formulation groups are at the forefront of toxicity formation, though this varies depending on the parameters.

Similarities and differences between IL11 and IL11RA1 knockout mice for lung fibro-inflammation, fertility and craniosynostosis

Loss of function (LOF) in IL11RA infers IL11 signaling as important for fertility, fibrosis, inflammation and incompletely penetrant craniosynostosis. The impact of LOF in IL11 has not been characterized. We generated IL11 knockout (Il11-/-) mice that are born in expected ratios and have normal hematological profiles. Lung fibroblasts from Il11-/- mice are resistant to pro-fibrotic stimulation with TGFβ1. Following bleomycin-induced lung injury, Il11-/- mice are protected from pulmonary fibrosis and exhibit lesser ERK, STAT3 and NF-kB activation, reduced Il1b, Timp1, Ccl2 and diminished IL6 expression, both at baseline and after injury: placing Il11 activity upstream of IL6 in this model. Il11-/- female mice are infertile. Unlike Il11ra1-/- mice, Il11-/- mice do not have craniosynostosis, have normal long bone mass and reduced body weights. These data further establish the role of IL11 signaling in lung fibrosis while suggesting that bone development abnormalities can be associated with mutation of IL11RA but not IL11, which may have implications for therapeutic targeting of IL11 signaling.