Characterisation of the pruritus responses and pruritic behaviours in an interleukin 31-induced canine model of pruritus

BACKGROUND

Intravenous administration of interleukin (IL)-31 in healthy dogs has been used as a model to assess antipruritic drugs. However, there is no known in-depth characterisation of pruritic behaviours, and the repeatability of the IL-31-induced pruritus in the individual dogs is currently unknown.

OBJECTIVES

To evaluate the immediate/delayed pruritus responses and the pruritic behaviours observed in the IL-31-induced pruritic model in healthy dogs after repeated IL-31 injections.

ANIMALS

Fifteen healthy laboratory beagles.

METHODS

All dogs were video-recorded for 270 min after two intravenous recombinant IL-31 injections (1.75 μg/kg) and vehicle (phosphate-buffered saline, control) injections, respectively; interventions were randomised and performed with a 2 week wash-out period. Two blinded investigators reviewed the pruritic behaviours of all video recordings.

RESULTS

Both canine IL-31 (IL-31_01, IL-31_02) injections significantly increased pruritic seconds and categorical minutes ('YES'/'NO' behaviour per discrete 1 min interval) in healthy dogs compared with both vehicle groups (Vehicle_01, Vehicle_02). The second intravenous canine IL-31 (IL-31_02) administered 14 days after the first IL-31 injection induced a significant increase in pruritic seconds (p = 0.021) and not pruritic categorical minutes (p = 0.231). An increase in pruritic seconds was observed in both IL-31 groups in the first 30 min post-administration, while there was no significant difference between IL-31 and vehicle groups.

CONCLUSIONS AND CLINICAL RELEVANCE

In conclusion, intravenous IL-31 reproducibly induces itch responses in dogs. Future evaluations of the canine IL-31 pruritic model should assess total pruritic behaviours in seconds rather than using a biased 'YES/NO' behaviour per 1 min scoring system.

Therapeutic effects of vitamin D and IL-22 on methotrexate-induced mucositis in mice

Mucositis is a common side effect of cancer therapies and transplant conditioning regimens. Management of mucositis involves multiple approaches from oral hygiene, anti-inflammatory, anti-apoptotic, cytoprotective, and antioxidant agents, to cryo-therapy, physical therapy, and growth factors. There is room for novel, affordable treatment options, or improvement of currently available therapies. Vitamin D has been shown to regulate mucosa-resident cell populations such as Th17 or innate lymphoid cells and critical mucosal cytokine IL-22; however, their therapeutic potential has not been put to test in preclinical mouse models. In this study, we aimed to test the therapeutic potential of vitamin D injections and IL-22 overexpression in a murine model of chemotherapy-induced mucositis. Balb/c mice were given daily intraperitoneal injections of vitamin D. Mucositis was induced by methotrexate. Another group received IL-22 plasmid via hydrodynamic gene delivery. Weight loss and intestinal histopathology, intestinal levels of cytokines IL-22, IL-17A, GM-CSF, IL-23, IFN-γ, TNF-α, and IL-10, and number of intestinal lamina propria B cell, neutrophil, and total innate lymphoid cells were quantified. Daily vitamin D injections ameliorated intestinal inflammation and elevated intestinal IL-22 levels compared with control groups. Temporal overexpression of IL-22 by hydrodynamic gene delivery slightly increased intestinal IL-22 but failed to confer significant protection from mucositis. To our knowledge, this is the first experimental demonstration in an animal model of mucositis of therapeutic use of vitamin D and IL-22 supplementation and our results with vitamin D suggest it may have merit in further trials in human mucositis patients.

IL-38 and IL-36 Target Autophagy for Regulating Synoviocyte Proliferation, Migration, and Invasion in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease leading to severe joint damage and disability. Fibroblast-like synoviocytes (FLSs) mostly contribute to the joint inflammation and destruction in RA through distinct mechanisms. However, little is known about newly discovered interleukin- (IL-) 36 and IL-38 involving in the pathology of RA. Here, we assessed the effect of IL-36 and IL-38 on RA-FLS function using IL-36 and IL-38 overexpression plasmids. We found that IL-36 inhibited synoviocytes proliferation while IL-38 showed an opposite influence. Furthermore, IL-36 and IL-38 significantly sequestered or accelerated RA-FLS migration and invasion capacity, respectively. Mechanically, IL-36 and IL-38 targeted autophagy for RA-FLS modulation. Using autophagy inhibitor 3-MA and inducer compound rapamycin, we found that autophagy negatively regulated the survival, migration, and invasion of synovial cells. Based on these results, IL-38 in combination with autophagy inhibitor 3-MA treatment demonstrated the strongest blockage of the above three activities of RA-FLS, and IL-38 overexpression reversed rapamycin-inhibited cell proliferation, migration, and invasion. Moreover, injection of IL-36 can improve the symptoms of RA in a rat model of RA. Taken together, we conclude that IL-38 and IL-36 target autophagy for regulating synoviocyte proliferation, migration, and invasion in RA.

Multiparametric magnetic resonance imaging/magnetic resonance elastography assesses progression and regression of steatosis, inflammation, and fibrosis in alcohol-associated liver disease

BACKGROUND

Magnetic resonance imaging (MRI) and MRI-based elastography (MRE) are the most promising noninvasive techniques in assessing liver diseases. The purpose of this study was to evaluate an advanced multiparametric imaging method for staging disease and assessing treatment response in realistic preclinical alcohol-associated liver disease (ALD).

METHODS

We utilized four different preclinical mouse models in our study: Model 1-mice were fed a fast-food diet and fructose water for 48 weeks to induce nonalcoholic fatty liver disease; Model 2-mice were fed chronic-binge ethanol (EtOH) for 10 days or 8 weeks to induce liver steatosis/inflammation. Two groups of mice were treated with interleukin-22 at different time points to induce disease regression; Model 3-mice were administered CCl4 for 2 to 4 weeks to establish liver fibrosis followed by 2 or 4 weeks of recovery; and Model 4-mice were administered EtOH plus CCl4 for 12 weeks. Mouse liver imaging biomarkers including proton density fat fraction (PDFF), liver stiffness (LS), loss modulus (LM), and damping ratio (DR) were assessed. Liver and serum samples were obtained for histologic and biochemical analyses. Ordinal logistic regression and generalized linear regression analyses were used to model the severity of steatosis, inflammation, and fibrosis, and to assess the regression of these conditions.

RESULTS

Multiparametric models with combinations of biomarkers (LS, LM, DR, and PDFF) used noninvasively to predict the histologic severity and regression of steatosis, inflammation, and fibrosis were highly accurate (area under the curve > 0.84 for all). A three-parameter model that incorporates LS, DR, and ALT predicted histologic fibrosis progression (r = 0.84, p < 0.0001) and regression (r = 0.79, p < 0.0001) as measured by collagen content in livers.

CONCLUSION

This preclinical study provides evidence that multiparametric MRI/MRE can be used noninvasively to assess disease severity and monitor treatment response in ALD.

Prior transient exposure to interleukin-21 delivered by recombinant adeno-associated virus vector protects mice from hepatitis B virus persistence

Chronic infection of hepatitis B virus (HBV) is a high risk factor for hepatic diseases, such as liver fibrosis, cirrhosis and hepatocellular carcinoma. Non-responders and hyporesponders to HBV vaccine are not protected from HBV infection. Patients that achieve autonomous or treatment-induced recovery are at risk of reactivation due to persistence of HBV covalently closed circular DNA (cccDNA) in hepatocytes. Interleukin 21 (IL-21) is a key regulator of HBV clearance in mouse models of HBV persistence: IL-21-based therapies effectively induces HBV clearance and protects mice from subsequent re-challenge. In this study, we explore the possibility of using IL-21 as prophylaxis against HBV by using mouse models of HBV persistence. HBV-naïve mice were transiently exposed to exogenous IL-21 through injection with recombinant adeno-associated virus expressing mouse IL-21 (AAV-IL-21). After extraneous IL-21 protein and DNA had become undetectable, mice were challenged with persistence-inducing HBV replicon plasmid through hydrodynamic injection. Viral persistence was analyzed by measuring viral antigens and DNA markers in serum and intrahepatic HBV DNA. For mechanistic studies, CD8⁺ T cell functions were blocked by repeated intraperitoneal injections of CD8 monoclonal antibodies in HBV-challenged mice. AAV-IL-21-injected mice quickly cleared HBV after HBV replicon challenge. In contrast, untreated mice and mice injected with control virus (AAV-Ctrl) allowed establishment of HBV persistence. Mechanistically, mice with prior IL-21 exposure displayed marked intrahepatic CD8⁺ T cell infiltrations, and CD8 blocking experiments demonstrated that CD8⁺ T cell responses functionally contributed toward clearance.

A mouse-adapted model of SARS-CoV-2 to test COVID-19 countermeasures

Coronaviruses are prone to transmission to new host species, as recently demonstrated by the spread to humans of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of the coronavirus disease 2019 (COVID-19) pandemic1. Small animal models that recapitulate SARS-CoV-2 disease are needed urgently for rapid evaluation of medical countermeasures2,3. SARS-CoV-2 cannot infect wild-type laboratory mice owing to inefficient interactions between the viral spike protein and the mouse orthologue of the human receptor, angiotensin-converting enzyme 2 (ACE2)4. Here we used reverse genetics5 to remodel the interaction between SARS-CoV-2 spike protein and mouse ACE2 and designed mouse-adapted SARS-CoV-2 (SARS-CoV-2 MA), a recombinant virus that can use mouse ACE2 for entry into cells. SARS-CoV-2 MA was able to replicate in the upper and lower airways of both young adult and aged BALB/c mice. SARS-CoV-2 MA caused more severe disease in aged mice, and exhibited more clinically relevant phenotypes than those seen in Hfh4-ACE2 transgenic mice, which express human ACE2 under the control of the Hfh4 (also known as Foxj1) promoter. We demonstrate the utility of this model using vaccine-challenge studies in immune-competent mice with native expression of mouse ACE2. Finally, we show that the clinical candidate interferon-λ1a (IFN-λ1a) potently inhibits SARS-CoV-2 replication in primary human airway epithelial cells in vitro-both prophylactic and therapeutic administration of IFN-λ1a diminished SARS-CoV-2 replication in mice. In summary, the mouse-adapted SARS-CoV-2 MA model demonstrates age-related disease pathogenesis and supports the clinical use of pegylated IFN-λ1a as a treatment for human COVID-196.

Safety and Immunological Evaluation of Interleukin-21 Plus Anti-α4β7 mAb Combination Therapy in Rhesus Macaques

Human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) infections compromise gut immunological barriers, inducing high levels of inflammation and a severe depletion of intestinal CD4+ T cells. Expression of α4β7 integrin promotes homing of activated T cells to intestinal sites where they become preferentially infected; blockade of α4β7 with an anti-α4β7 monoclonal antibody (mAb) prior to infection has been reported to reduce gut SIV viremia in rhesus macaques (RMs). Interleukin-21 (IL-21) administration in antiretroviral therapy-treated, SIV-infected RMs reduces gut inflammation and improves gut integrity. We therefore hypothesized that the combination of IL-21 and anti-α4β7 mAb therapies could synergize to reduce inflammation and HIV persistence. We co-administered two intravenous doses of rhesus anti-α4β7 mAb (50 mg/kg) combined with seven weekly subcutaneous infusions of IL-21-IgFc (100 μg/kg) in four healthy, SIV-uninfected RMs to evaluate the safety and immunological profiles of this intervention in blood and gut. Co-administration of IL-21 and anti-α4β7 mAb showed no toxicity at the given dosages as assessed by multiple hematological and chemical parameters and did not alter the bioavailability of the therapeutics or result in the generation of antibodies against the anti-α4β7 mAb or IL-21-IgFc. Upon treatment, the frequency of CD4 memory T cells expressing β7 increased in blood and decreased in gut, consistent with an inhibition of activated CD4 T-cell homing to the gut. Furthermore, the frequency of T cells expressing proliferation and immune activation markers decreased in blood and, more profoundly, in gut. The combined IL-21 plus anti-α4β7 mAb therapy is well-tolerated in SIV-uninfected RMs and reduces the gut homing of α4β7+ CD4 T cells as well as the levels of gut immune activation.

IL-22 promotes tumor growth of breast cancer cells in mice

Increased interleukin-22 (IL-22) level was reported to associate with progression of breast cancer. Regulation of IL-22 in breast cancer still needs to be elucidated. We assessed the effect of giving IL-22 in tumor growth of mice inoculated with 4T1, MCF7 and MDA-MB-231 breast cancer cells. IL-22-producing cells were analyzed in tumor tissues. We also analyzed the impact of giving IL-1β and IL-23 on IL-22 levels in tumor tissues. Giving exogenous IL-22 increased tumor size and intra-tumor Ki-67-positive cells in vivo. IL-22 increased phosphorylated STAT3 level and proliferation of breast cancer cells in vitro, an effect blocked by a STAT3-inhibitor stattic. Endogenous IL-22 mRNA level was up-regulated in tumor tissue, compared with normal mammary tissue. Innate lymphoid cell group 3 (ILC3) is a major producer of IL-22 in 4T1 tumor. Giving IL-1β and/or IL-23 increased cell proliferation in 4T1 tumor, which was reversed by concurrent use of an IL-22 neutralization antibody. IL-1β and IL-23 increased levels of IL-22 mRNA and IL-22-producing ILC3 in 4T1 tumor. Our findings suggest a mechanism for how IL-22 regulates tumor growth in breast cancer, and indicate blocking IL-22 function might reduce IL-1β- and IL-23-induced tumor progression of breast cancer.

Secretion of Recombinant Interleukin-22 by Engineered Lactobacillus reuteri Reduces Fatty Liver Disease in a Mouse Model of Diet-Induced Obesity

The incidence of metabolic syndrome continues to rise globally. In mice, intravenous administration of interleukin-22 (IL-22) ameliorates various disease phenotypes associated with diet-induced metabolic syndrome. In patients, oral treatment is favored over intravenous treatment, but methodologies to deliver IL-22 via the oral route are nonexistent. The goal of this study was to assess to what extent engineered Lactobacillus reuteri secreting IL-22 could ameliorate nonalcoholic fatty liver disease. We used a mouse model of diet-induced obesity and assessed various markers of metabolic syndrome following treatment with L. reuteri and a recombinant derivative. Mice that received an 8-week treatment of wild-type probiotic gained less weight and had a smaller fat pad than the control group, but these phenotypes were not further enhanced by recombinant L. reuteri However, L. reuteri secreting IL-22 significantly reduced liver weight and triglycerides at levels that exceeded those of the probiotic wild-type treatment group. Our findings are interesting in light of the observed phenotypes associated with reduced nonalcoholic liver disease, in humans the most prevalent chronic liver disease, following treatment of a next-generation probiotic that is administered orally. Once biological and environmental containment strategies are in place, therapeutic applications of recombinant Lactobacillus reuteri are on the horizon.IMPORTANCE In humans, nonalcoholic fatty liver disease (NAFLD) is the most prevalent liver disease due to the increased prevalence of obesity. While treatment of NAFLD is often geared toward lifestyle changes, such as diet and exercise, the use of dietary supplements such as probiotics is underinvestigated. Here, we report that probiotic Lactobacillus reuteri reduces fatty liver in a mouse model of diet-induced obesity. This phenotype was further enhanced upon delivery of recombinant interleukin-22 by engineered Lactobacillus reuteri These observations pave the road to a better understanding of probiotic mechanisms driving the reduction of diet-induced steatosis and to development of next-generation probiotics for use in the clinic. Ultimately, these studies may lead to rational selection of (engineered) probiotics to ameliorate fatty liver disease.

Interleukin 27 Protects From Gastric Atrophy and Metaplasia During Chronic Autoimmune Gastritis

BACKGROUND & AIMS

The association between chronic inflammation and gastric carcinogenesis is well established, but it is not clear how immune cells and cytokines regulate this process. We investigated the role of interleukin 27 (IL27) in the development of gastric atrophy, hyperplasia, and metaplasia (preneoplastic lesions associated with inflammation-induced gastric cancer) in mice with autoimmune gastritis.

METHODS

We performed studies with TxA23 mice (control mice), which express a T-cell receptor against the H+/K+ adenosine triphosphatase α chain and develop autoimmune gastritis, and TxA23xEbi3-/- mice, which develop gastritis but do not express IL27. In some experiments, mice were given high-dose tamoxifen to induce parietal cell atrophy and spasmolytic polypeptide-expressing metaplasia (SPEM). Recombinant IL27 was administered to mice with mini osmotic pumps. Stomachs were collected and analyzed by histopathology and immunofluorescence; we used flow cytometry to measure IL27 and identify immune cells that secrete IL27 in the gastric mucosa. Single-cell RNA sequencing was performed on immune cells that infiltrated stomach tissues.

RESULTS

We identified IL27-secreting macrophages and dendritic cell in the corpus of mice with chronic gastritis (TxA23 mice). Mice deficient in IL27 developed more severe gastritis, atrophy, and SPEM than control mice. Administration of recombinant IL27 significantly reduced the severity of inflammation, atrophy, and SPEM in mice with gastritis. Single-cell RNA sequencing showed that IL27 acted almost exclusively on stomach-infiltrating CD4+ T cells to suppress expression of inflammatory genes.

CONCLUSIONS

In studies of mice with autoimmune gastritis, we found that IL27 is an inhibitor of gastritis and SPEM, suppressing CD4+ T-cell-mediated inflammation in the gastric mucosa.

Interleukin-22 ameliorates acute-on-chronic liver failure by reprogramming impaired regeneration pathways in mice

BACKGROUND & AIMS

Acute-on-chronic liver failure (ACLF) is a clinical syndrome defined by liver failure on pre-existing chronic liver disease. It is often associated with bacterial infection and high short-term mortality. Experimental models that fully reproduce ACLF are lacking, so too are effective pharmacological therapies for this condition.

METHODS

To mimic ACLF conditions, we developed a severe liver injury model by combining chronic injury (chronic carbon tetrachloride [CCl4] injection), acute hepatic insult (injection of a double dose of CCl4), and bacterial infection (intraperitoneal injection of bacteria). Serum and liver samples from patients with ACLF or acute drug-induced liver injury (DILI) were used. Liver injury and regeneration were assessed to ascertain the potential benefits of interleukin-22 (IL-22Fc) administration.

RESULTS

This severe liver injury model recapitulated some of the key features of clinical ACLF, including acute-on-chronic liver injury, bacterial infection, multi-organ injury, and high mortality. Liver regeneration in this model was severely impaired because of a shift from the activation of the pro-regenerative IL-6/STAT3 pathway to the anti-regenerative IFN-γ/STAT1 pathway. The impaired IL-6/STAT3 activation was due to the inability of Kupffer cells to produce IL-6; whereas the enhanced STAT1 activation was due to a strong innate immune response and subsequent production of IFN-γ. Compared to patients with DILI, patients with ACLF had higher levels of IFN-γ but lower liver regeneration. IL-22Fc treatment improved survival in ACLF mice by reversing the STAT1/STAT3 pathway imbalance and enhancing expression of many antibacterial genes in a manner involving the anti-apoptotic protein BCL2.

CONCLUSIONS

Acute-on-chronic liver injury or bacterial infection is associated with impaired liver regeneration due to a shift from a pro-regenerative to an anti-regenerative pathway. IL-22Fc therapy reverses this shift and attenuates bacterial infection, thus IL-22Fc may have therapeutic potential for ACLF treatment.

LAY SUMMARY

A mouse model combining chronic liver injury, acute hepatic insult, and bacterial infection recapitulates some of the key features of acute-on-chronic liver failure (ACLF) in patients. Both fibrosis and bacterial infection contribute to the impaired regenerative capacity of the liver in patients with ACLF. Herein, we show that IL-22Fc therapy improves ACLF by reprogramming impaired regenerative pathways and attenuating bacterial infection. Thus, it may have therapeutic potential for patients with ACLF.

Interleukin-22 promotes development of malignant lesions in a mouse model of spontaneous breast cancer

Interleukin (IL)-22 is recognized as a tumor-supporting cytokine and is implicated in the proliferation of multiple epithelial cancers. In breast cancer, the current knowledge of IL-22 function is based on cell line models and little is known about how IL-22 affects the tumor initiation, proliferation, invasion, and metastasis in the in vivo system. Here, we investigated the tumor stage-specific function of IL-22 in disease development by evaluating the stage-by-stage progression of breast cancer in an IL-22 knockout spontaneous breast cancer mouse model. We found that among all the stages, IL-22 is specifically upregulated in tumor microenvironment (TME) during the malignant transformation stage of breast tumor progression. The deletion of IL-22 gene leads to the arrest of malignant transition stage, and reduced invasion and tumor burden. Administration of recombinant IL-22 in the TME does not influence in vivo tumor initiation and proliferation but only promotes malignant transformation of cancer cells. Mechanistically, deletion of IL-22 gene causes downregulation of epithelial-to-mesenchymal transition (EMT)-associated transcription factors in breast tumors, suggesting EMT as the mechanism of regulation of malignancy by IL-22. Clinically, in human breast tumor tissues, increased number of IL-22+ cells in the TME is associated with an aggressive phenotype of breast cancer. For the first time, this study provides an insight into the tumor stage-specific function of IL-22 in breast tumorigenesis.

Interleukin-22 Attenuated Renal Tubular Injury in Aristolochic Acid Nephropathy via Suppressing Activation of NLRP3 Inflammasome

Aristolochic acid nephropathy (AAN), as a rapidly progressive interstitial nephropathy due to excessive ingestion of aristolochia herbal medications, has recently raised considerable concerns among clinicians and researchers as its underlying pathogenic mechanisms are largely unclear. In the current study, we identified NLRP3 inflammasome activation as a novel pathological mechanism of AAN. We found that NLRP3 inflammasome was aberrantly activated both in vivo and in vitro after AA exposure. Blockade of IL-1β and NLRP3 inflammasome activation by IL-1Ra significantly attenuated renal tubular injury and function loss in AA-induced nephropathy. Moreover, NLRP3 or Caspase-1 deficiency protected against renal injury in the mouse model of acute AAN, suggesting that the NLRP3 signaling pathway was probably involved in the pathogenesis of AAN. We also found that administration of IL-22 could markedly attenuate renal tubular injury in AAN. Notably, IL-22 intervention significantly alleviated renal fibrosis and dysfunction in AA-induced nephropathy. Furthermore, IL-22 largely inhibited renal activation of NLRP3 inflammasome in AA-induced nephropathy. These results indicated that IL-22 ameliorated renal tubular injury in AAN through suppression of NLRP3 inflammasome activation. In summary, this study identified renal activation of NLRP3 inflammasome as a novel mechanism underlying the pathogenesis of AAN, thus providing a potential therapeutic strategy for AAN based on suppression of NLRP3 inflammasome activation.

Randomized Phase I Healthy Volunteer Study of UTTR1147A (IL-22Fc): A Potential Therapy for Epithelial Injury

Most treatments for epithelial injury target hematopoietic mechanisms, possibly causing immunosuppression. Interleukin (IL)-22 promotes tissue regeneration, acting directly on epithelial cells. UTTR1147A, a human IL-22Fc (immunoglobulin G (IgG)4) fusion protein, activates IL-22 signaling. This phase I placebo-controlled trial of single, ascending, i.v. (1-120 μg/kg) and s.c (3-120 μg/kg) doses of UTTR1147A analyzed its effects on safety, tolerability, pharmacokinetics, and pharmacodynamic biomarkers in healthy volunteers. Most adverse events (AEs) were mild or moderate. The maximum tolerated i.v. dose in healthy volunteers was 90 μg/kg. Predominant AEs were dose-dependent reversible skin effects consistent with IL-22 pharmacology. UTTR1147A exposure increased approximately dose-proportionally, with a half-life of ~1 week. IL-22 biomarkers (regenerating islet protein 3A (REG3A), serum amyloid A (SAA), and C-reactive protein (CRP)) increased dose-dependently. Neither inflammatory symptoms and signs nor cytokines increased with CRP elevations. UTTR1147A demonstrated acceptable safety, pharmacokinetics, and IL-22R engagement, supporting further clinical development.

Nonclinical safety assessment of a human interleukin-22FC IG fusion protein demonstrates in vitro to in vivo and cross-species translatability

Although Interleukin-22 (IL-22) is produced by various leukocytes, it preferentially targets cells with epithelial origins. IL-22 exerts essential roles in modulating various tissue epithelial functions, such as innate host defense against extracellular pathogens, barrier integrity, regeneration, and wound healing. Therefore, IL-22 is thought to have therapeutic potential in treating diseases associated with infection, tissue injury or chronic tissue damage. A number of in vitro and in vivo nonclinical studies were conducted to characterize the pharmacological activity and safety parameters of UTTR1147A, an IL-22 recombinant fusion protein that links the human cytokine IL-22 with the Fc portion of a human immunoglobulin. To assess the pharmacological activity of UTTR1147A, STAT3 activation was evaluated in primary hepatocytes isolated from human, cynomolgus monkey, minipig, rat, and mouse after incubation with UTTR1147A. UTTR1147A activated STAT3 in all species evaluated, demonstrating that all were appropriate nonclinical species for toxicology studies. The nonclinical safety profile of UTTR1147A was evaluated in rats, minipigs, and cynomolgus monkeys to establish a safe clinical starting dose for humans in Phase I trials and to support clinical intravenous, subcutaneous and/or topical administration treatment regimen. Results demonstrate the cross-species translatability of the biological response in activating the IL-22 pathway as well as the translatability of findings from in vitro to in vivo systems. UTTR1147A was well tolerated in all species tested and induced the expected pharmacologic effects of epidermal hyperplasia and a transient increase in on-target acute phase proteins. These effects were all considered to be clinically predictable, manageable, monitorable, and reversible.

TNFα gene silencing mediated by orally targeted nanoparticles combined with interleukin-22 for synergistic combination therapy of ulcerative colitis

Pro-resolving factors that are critical for colonic epithelial restitution were down-regulated during the treatment with inhibitor of pro-inflammatory cytokines (e.g., anti-TNFα antibody) in ulcerative colitis (UC) therapy. We hypothesized that increased amounts of factors such as interleukin-22 (IL-22) during the therapeutic inhibition of TNFα could facilitate the resolution of intestinal inflammation. As combination therapy is an emerging strategy for UC treatment, we attempt to treat established UC based on the combination of TNFα siRNA (siTNF) and IL-22. Initially, we loaded siTNF into galactosylated polymeric nanoparticles (NPs). The resultant Gal-siTNF-NPs had a desirable average diameter (~261 nm), a narrow size distribution and a slightly negative surface charge (~-6 mV). These NPs successfully mediated the targeted delivery of siTNF to macrophages and efficiently inhibited the expression of TNFα. Meanwhile, IL-22 could obviously accelerate mucosal healing. More importantly, oral administration of Gal-siTNF-NPs plus IL-22 embedded in a hydrogel (chitosan/alginate) showed much stronger capacities to down-regulate the expression of pro-inflammatory factors and promote mucosal healing. This formulation also yielded a much better therapeutic efficacy against UC in a mouse model compared to hydrogel loaded with Gal-siTNF-NPs or IL-22 alone. Our results strongly demonstrate that Gal-siTNF-NP/IL-22-embedded hydrogel can target to inflamed colon, and co-deliver siTNF and IL-22 to boost the effects of either monotherapy, which may become a promising oral drug formulation and enable targeted combination therapy of UC.

Liver-heart crosstalk controls IL-22 activity in cardiac protection after myocardial infarction

Interleukin (IL)-22 regulates tissue inflammation and repair. Here we report participation of the liver in IL-22-mediated cardiac repair after acute myocardial infarction (MI). Methods: We induced experimental MI in mice by ligation of the left ascending artery and evaluated the effect of IL-22 on post-MI cardiac function and ventricular remodeling. Results: Daily subcutaneous injection of 100 µg/kg mouse recombinant IL-22 for seven days attenuated adverse ventricular remodeling and improved cardiac function in mice at 28 days after left anterior descending coronary artery ligation-induced MI. Pharmacological inhibition of signal transducer and activator of transcription (STAT3) muted these IL-22 activities. While cardiomyocyte-selective depletion of STAT3 did not affect IL-22 activities in protecting post-MI cardiac injury, hepatocyte-specific depletion of STAT3 fully muted these IL-22 cardioprotective activities. Hepatocyte-derived fibroblast growth factor (FGF21) was markedly increased in a STAT3-dependent manner following IL-22 administration and accounted for the cardioprotective benefit of IL-22. Microarray analyses revealed that FGF21 controlled the expression of cardiomyocyte genes that are involved in cholesterol homeostasis, DNA repair, peroxisome, oxidative phosphorylation, glycolysis, apoptosis, and steroid responses, all of which are responsible for cardiomyocyte survival. Conclusions: Supplementation of IL-22 in the first week after acute MI effectively prevented left ventricular dysfunction and heart failure. This activity of IL-22 involved crosstalk between the liver and heart after demonstrating a role of the hepatic STAT3-FGF21 axis in IL-22-induced post-MI cardiac protection.

Enhanced autophagy contributes to protective effects of IL-22 against acetaminophen-induced liver injury

Acute or acute-on-chronic liver failure is a leading cause of death in liver diseases without effective treatment. Interleukin-22 (IL-22) is currently in clinical trials for the treatment of severe alcoholic hepatitis, but the underlying mechanisms remain to be explored. Autophagy plays a critical role in alleviating liver injury. The aim of the current study is to explore the role of autophagy in IL-22-mediated hepato-protective effect against acetaminophen (APAP)-induced liver injury. Methods: A model of acute liver injury induced by APAP was used in vivo. IL-22 was administrated to the APAP-treated mice. Hepatocytes were pre-incubated with IL-22, followed by exposure to APAP for in vitro analyses. Results: IL-22 administration significantly reduced serum ALT and AST, hepatic reactive oxygen species, and liver necrosis in APAP-challenged mice. APAP treatment increased hepatic autophagosomes, which was further intensified by IL-22 co-treatment. Hepatic LC3-II was moderately upregulated after APAP administration without obvious alteration of phosphorylation of AMP-activated kinase (p-AMPK). IL-22 pretreatment significantly upregulated hepatic LC3-II and p-AMPK in APAP-treated mice. IL-22 also alleviated APAP-induced cytotoxicity and upregulated LC3-II and p-AMPK expression in cultured hepatocytes treated with APAP in vitro. When p-AMPK was blocked with compound C (an AMPK inhibitor), IL-22-mediated LC3-II conversion and protection against APAP-induced cytotoxicity was weakened. Conclusions: Enhanced AMPK-dependent autophagy contributes to protective effects of IL-22 against APAP-induced liver injury.

Lentiviral delivery of novel fusion protein IL12/FasTI for cancer immune/gene therapy

Many of the cytokine-based cancer immunotherapies are hindered by the devastating side effects of systemic delivery of the cytokines. To address this problem, we previously described a novel approach to locally achieve high doses of interleukin-12 (IL-12) in tumors and demonstrated that bi-functional fusion protein mIL-12/FasTI expressed by stable clones of TC-1 cells efficiently suppressed tumor proliferation by activating natural killer (NK) cells and other cytolytic killer cells and sending apoptotic signals into tumor cells. In the present study, we employed a lentiviral vector-based gene delivery system to deliver this fusion construct directly into tumor cells. We show that lentiviral vector efficiently delivers the fusion constructs into Hela cells in vitro as assayed by RT-PCR and immunohistochemistry (IHC). We also confirm that fusion protein mIL-12/FasTI delivered by the viral vector significantly enhanced killer cell activation, increased caspase-3 activity and decreased tumor growth in vitro. This study offers a further step for fusion protein cancer therapy for cancer patients.

IL-22: There Is a Gap in Our Knowledge

IL-22 is a critical cytokine in modulating tissue responses during inflammation. IL-22 is upregulated in many chronic inflammatory diseases, making IL-22 biology a potentially rewarding therapeutic target. However, this is complicated by the dual-natured role of IL-22 in inflammation, as the cytokine can be protective or inflammatory depending on the disease model. Although scientific interest in IL-22 has increased considerably in the past 10 y, there is still much we do not know about the environmental, cellular, and molecular factors that regulate the production and function of this cytokine. A better understanding of IL-22 biology will allow us to develop new or improved therapeutics for treating chronic inflammatory diseases. In this article, I will highlight some of the outstanding questions in IL-22 biology.

IL-35 is a Protective Immunomodulator in Brain Ischemic Injury in Mice

IL-35 has been identified as a novel anti-inflammatory cytokine that belongs to the IL-12 cytokine family and has been verified to play a protective role in autoimmune diseases. In this study, we investigated the protective effects of IL-35 on cerebral ischemia/reperfusion (I/R) injury in a middle cerebral artery occlusion mouse model. We determined that the expression of IL-35 was initially decreased and subsequently increased in I/R injury. Moreover, IL-35 (i.c.v.) pre- and posttreatment significantly reduced the infarct volume and improved neurological deficits after 45 min of ischemia and 24 h of reperfusion. Importantly, IL-35 treatment improved neurological function recovery, particularly in balance ability, at 14 days after treatment. Finally, our results showed that IL-35 treatment reduced the expression of IL-6 and IL-1β, which are confirmed proinflammatory cytokines, thus indicating that these cytokines have both been linked to the anti-inflammatory mechanisms of IL-35. Therefore, IL-35 may be a key immune mediator in brain ischemic injury and appears to have promising potential for clinical trials.

A Prominent Role of Interleukin-18 in Acetaminophen-Induced Liver Injury Advocates Its Blockage for Therapy of Hepatic Necroinflammation

Acetaminophen [paracetamol, N-acetyl-p-aminophenol (APAP)]-induced acute liver injury (ALI) not only remains a persistent clinical challenge but likewise stands out as well-characterized paradigmatic model of drug-induced liver damage. APAP intoxication associates with robust hepatic necroinflammation the role of which remains elusive with pathogenic but also pro-regenerative/-resolving functions being ascribed to leukocyte activation. Here, we shine a light on and put forward a unique role of the interleukin (IL)-1 family member IL-18 in experimental APAP-induced ALI. Indeed, amelioration of disease as previously observed in IL-18-deficient mice was further substantiated herein by application of the IL-18 opponent IL-18-binding protein (IL-18BPd:Fc) to wild-type mice. Data altogether emphasize crucial pathological action of this cytokine in APAP toxicity. Adding recombinant IL-22 to IL-18BPd:Fc further enhanced protection from liver injury. In contrast to IL-18, the role of prototypic pro-inflammatory IL-1 and tumor necrosis factor-α is controversially discussed with lack of effects or even protective action being repeatedly reported. A prominent detrimental function for IL-18 in APAP-induced ALI as proposed herein should relate to its pivotal role for hepatic expression of interferon-γ and Fas ligand, both of which aggravate APAP toxicity. As IL-18 serum levels increase in patients after APAP overdosing, targeting IL-18 may evolve as novel therapeutic option in those hard-to-treat patients where standard therapy with N-acetylcysteine is unsuccessful. Being a paradigmatic experimental model of ALI, current knowledge on ill-fated properties of IL-18 in APAP intoxication likewise emphasizes the potential of this cytokine to serve as therapeutic target in other entities of inflammatory liver diseases.

Interferon lambda1/IL-29 and inorganic polyphosphate are novel regulators of neutrophil-driven thromboinflammation

Neutrophils and neutrophil-released meshwork structures termed neutrophil extracellular traps (NETs) are major mediators of thromboinflammation and emerging targets for therapy, yet the mechanisms and pathways that control the role of neutrophils in thromboinflammation remain poorly understood. Here, we explored the role of IFN-λ1/IL-29, a major antiviral cytokine recently shown to suppress the neutrophil migratory capacity, in prothrombotic and proNETotic functions of neutrophils. In an ex vivo human experimental setting of acute ST-segment elevation myocardial infarction (STEMI), we show that IFN-λ1/IL-29 hinders NET release and diminishes the amount of cytoplasmic TF in neutrophils. Since platelet-neutrophil interaction plays a major role in NET-induced thromboinflammation, we further studied how IFN-λ1/IL-29 may interrupt this interaction. In this context, we identified inorganic polyphosphate (polyP) as a platelet-derived NET inducer in STEMI. In arterial STEMI thrombi, polyP was present in platelets and in close proximity to NET remnants. PolyP release from activated platelets was dependent on thrombin present in infarcted artery plasma, resulting in NET formation by promoting mTOR inhibition and autophagy induction. The effect of polyP on mTOR inhibition was counteracted by IFN-λ1/IL-29 treatment, leading to inhibition of NET formation. Consistently, we show in an in vivo model of FeCl3 -induced arterial thrombosis that IFN-λ2/IL-28A exerts strong antithrombotic potential. Taken together, these findings reveal a novel function of IFN-λ1/IL-29 in the suppression of thromboinflammation. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

IL-21 Augments Rapamycin in Expansion of Alpha Fetoprotein Antigen Specific Stem-Cell-like Memory T Cells in vitro

INTRODUCTION

Alloreactive tumor specific T cells are important arsenals of the adaptive immune system in the fight against tumors. However, stem cell-like memory T cells (Tscm) provide the key to effective elimination of tumor cells. Methods for generating these T cell subsets already exist. However, they could be made more efficient. Further, they are expensive and unattainable to the resource poor laboratories. In this regard, we are hereby describing a novel in vitro allogeneic co-culture method for raising allo-restricted tumor specific Tscm cells that we developed.

METHODS

We started by obtaining PBLs that screened negative for HLA-A2 molecules from healthy donors followed by co-culture with T2/AFP cells to generate AFP peptide specific tumor-reactive T cells. Controls, IL-21 and/or rapamycin were applied to samples in 24 well plates. Samples were harvested and stained with anti-human CD3, CD8, CD44, CD62L, and HLA-A2/AFP dimer followed by flow cytometry analysis. Cell viability was measured by Trypan blue exclusion assay. One Way ANOVA and independent t test were used to compare the mean differences among and between groups where P values less than 0.05 were considered significant.

RESULTS

Our results show that rapamycin arrests the differentiation of, and expands AFP specific Tscm cells. Further, the expansion of Tscm cells is augmented in the presence of IL-21.

CONCLUSION

IL-21 and Rapamycin can be used concurrently to raise and maintain antigen specific Tscm cells in vitro for purposes of augmenting immunotherapy strategies against cancers.

IL-22R Ligands IL-20, IL-22, and IL-24 Promote Wound Healing in Diabetic db/db Mice

Diabetic foot ulcers (DFU) are one of the major complications in type II diabetes patients and can result in amputation and morbidity. Although multiple approaches are used clinically to help wound closure, many patients still lack adequate treatment. Here we show that IL-20 subfamily cytokines are upregulated during normal wound healing. While there is a redundant role for each individual cytokine in this subfamily in wound healing, mice deficient in IL-22R, the common receptor chain for IL-20, IL-22, and IL-24, display a significant delay in wound healing. Furthermore, IL-20, IL-22 and IL-24 are all able to promote wound healing in type II diabetic db/db mice. Mechanistically, when compared to other growth factors such as VEGF and PDGF that accelerate wound healing in this model, IL-22 uniquely induced genes involved in reepithelialization, tissue remodeling and innate host defense mechanisms from wounded skin. Interestingly, IL-22 treatment showed superior efficacy compared to PDGF or VEGF in an infectious diabetic wound model. Taken together, our data suggest that IL-20 subfamily cytokines, particularly IL-20, IL-22, and IL-24, might provide therapeutic benefit for patients with DFU.

[GenomeLabTM GeXP analysis system to detect apoptosis-associated genes in A549 cells treated by recombinant human IL-24 combined with cisplatin]

Objective To investigate the changes of apoptosis-associated genes in human lung adenocarcinoma cell line A549 after treated by the recombinant human interleukin-24 (rhIL-24) combined with cisplatin (DDP). Methods The mRNA levels of Bax, Bcl-2, survivin, caspase-3, retinoblastoma (Rb) gene, p53 were analyzed by GenomeLab^TM GeXP genetic analysis system after A549 cells were treated with 160 ng/mL rhIL-24 or 3 μg/mL DDP or 160 ng/mL rhIL-24 combined with 3 μg/mL DDP. Results The rhIL-24 up-regulated the levels of Bax, Rb, caspase-3 mRNAs and down-regulated Bcl-2, survivin mRNAs, but the change of p53 mRNA was not regular. The combination of rhIL-24 and DDP strengthened the above changes. Conclusion The rhIL-24 protein can induce the apoptosis of A549 cells by up-regulating Bax, caspase-3, Rb mRNAs and down-regulating Bcl-2, survivin mRNAs.

Critical Role of IL-22/IL22-RA1 Signaling in Pneumococcal Pneumonia

IL-22-IL-22R signaling plays a crucial role in regulating host defenses against extracellular pathogens, particularly in the intestine, through the induction of antimicrobial peptides and chemotactic genes. However, the role of IL-22-IL-22R is understudied in Streptococcus pneumoniae lung infection, a prevalent pathogen of pneumonia. This paper presents the findings of IL-22 signaling during a murine model of pneumococcal pneumonia and improvement of bacterial burden upon IL-22 administration. IL-22 was rapidly induced in the lung during pneumococcal infection in wild-type mice, and Il22(-/-) mice had higher pneumococcal burdens compared with controls. Additionally, mice with hepatic-specific deletion of Il22ra1 also had higher bacterial burdens in lungs compared with littermate controls after intrapulmonary pneumococcal infection, suggesting that IL-22 signaling in the liver is important to control pneumococcal pneumonia. Thus, we hypothesized that enhancement of IL-22 signaling would control pneumococcal burden in lung tissues in an experimental pneumonia model. Administration of rIL-22 systemically to infected wild-type mice decreased bacterial burden in lung and liver at 24 h postinfection. Our in vitro studies also showed that mice treated with IL-22 had increased C3 expression in the liver compared with the isotype control group. Furthermore, serum from mice treated with IL-22 had improved opsonic capacity by increasing C3 binding on S. pneumoniae Taken together, endogenous IL-22 and hepatic IL-22R signaling play critical roles in controlling pneumococcal lung burden, and systemic IL-22 decreases bacterial burden in the lungs and peripheral organs by potentiating C3 opsonization on bacterial surfaces, through the increase of hepatic C3 expression.

Antibody-Based Targeted Delivery of Interleukin-22 Promotes Rapid Clinical Recovery in Mice With DSS-Induced Colitis

BACKGROUND

We have recently described the potential of the alternatively spliced extradomain A of fibronectin as a target for antibody-based pharmacodelivery applications in ulcerative colitis. Here, we report on the cloning and therapeutic properties of novel antibody-based fusion proteins, comprising the F8 antibody specific to extradomain A and murine interleukin (IL)-22, a globular cytokine belonging to the IL10 family. A protective function for IL22 in colitis has previously been described, as this cytokine induces antimicrobial, proliferative, and antiapoptotic pathways, preventing tissue damage and promoting epithelial repair.

METHODS

Two fusion proteins comprising IL22, fused at the N- or at the C-terminus of the F8 antibody in diabody format, were expressed in mammalian cells. The ability of radiolabeled preparations of the 2 fusion proteins to localize at sites of disease was assessed by autoradiography in a murine model of dextran sodium sulfate-induced colitis and by quantitative biodistribution analysis in a syngeneic mouse teratocarcinoma model. Therapeutic activity was assessed in mice with dextran sodium sulfate-induced colitis, which received intravenous injections of antibody-cytokine fusion proteins.

RESULTS

Both fusion proteins were able to selectively accumulate at the site of disease. The fusion protein with the cytokine moiety at the N-terminal extremity (IL22-F8) exhibited better results than the C-terminal fusion, both in terms of targeting selectivity and therapeutic efficacy. Mice treated with IL22-F8 showed a more rapid recovery from clinical symptoms compared with controls and improved macroscopic and microscopic morphology of the colon.

CONCLUSIONS

IL22-F8 is a promising biopharmaceutical drug candidate for the treatment of ulcerative colitis.

MALDI-MSI for the analysis of a 3D tissue-engineered psoriatic skin model

MALDI-MS Imaging is a novel label-free technique that can be used to visualize the changes in multiple mass responses following treatment. Following treatment with proinflammatory cytokine interleukin-22 (IL-22), the epidermal differentiation of Labskin, a living skin equivalent (LSE), successfully modeled psoriasis in vitro. Masson's trichrome staining enabled visualization and quantification of epidermal differentiation between the untreated and IL-22 treated psoriatic LSEs. Matrix-assisted laser desorption ionization mass spectrometry imaging was used to observe the spatial location of the psoriatic therapy drug acetretin following 48 h treatments within both psoriatic and normal LSEs. After 24 h, the drug was primarily located in the epidermal regions of both the psoriatic and nonpsoriatic LSE models whereas after 48 h it was detectible in the dermis.

Interleukin-35 upregulates OPG and inhibits RANKL in mice with collagen-induced arthritis and fibroblast-like synoviocytes

IL-35 is a novel anti-inflammatory cytokine, but the exact role of IL-35 in the progression of RA remains unclear, especially associated with osteoporosis and bone erosion. The present research has not been reported. Our purpose is to study how IL-35 affects RA bone destruction.

INTRODUCTION

This study investigated the effect of interleukin-35 (IL-35) on OPG and RANKL expression in collagen-induced arthritis (CIA) in rats and in cultured fibroblast-like synoviocytes (FLS).

METHODS

Thirty DBA/1J mice were randomly assigned to three groups (n = 10 per group): the control group, the CIA group, and the CIA + IL-35 group. Collagen-induced arthritis was induced by immunization with collagen. IL-35 was intraperitoneally injected daily for 10 days, starting from the 24(th) day after immunization. FLS cells were isolated and cultured from CIA. The expression of IL-17, RANKL, and OPG was determined by RT-PCR and Western blot. Each experiment was repeated three times.

RESULTS

CIA mice exhibited arthritis symptoms on day 24, followed by a rapid progression of arthritis. The expression of IL-17 and RANKL was increased and the expression of OPG was decreased in CIA mice compared with control mice. IL-35 treatment inhibited the development of arthritis in CIA mice, accompanied by a decrease in the expression of IL-17 and RANKL and an increase in the expression of OPG. Furthermore, IL-35 dose-dependently inhibited the expression of RANKL and increased the expression of OPG in cultured FLS cells.

CONCLUSION

IL-35 inhibits RANKL expression and increases OPG expression in CIA mice. IL-35 may be used for treating rheumatoid arthritis.

Interleukin-22 contributes to liver regeneration in mice with concanavalin A-induced hepatitis after hepatectomy

AIM

To investigate the therapeutic effects and mechanisms of interleukin (IL)-22 in liver regeneration in mice with concanavalin A (ConA)-induced liver injury following 70% hepatectomy.

METHODS

Mice were injected intravenously with ConA at 10 μg/g body weight 4 d before 70% hepatectomy to create a hepatitis model, and recombinant IL-22 was injected at 0.125 μg/g body weight 30 min prior to 70% hepatectomy to create a therapy model. Control animals received an intravenous injection of an identical volume of normal saline.

RESULTS

IL-22 treatment prior to 70% hepatectomy performed under general anesthesia resulted in reductions in the biochemical and histological evidence of liver injury, earlier proliferating cell nuclear antigen expression and accelerated recovery of liver mass. IL-22 pretreatment also significantly induced signal transducer and activator of transcription factor 3 (STAT3) activation and increased the expression of a variety of mitogenic proteins, such as Cyclin D1. Furthermore, alpha fetal protein mRNA expression was significantly elevated after IL-22 treatment.

CONCLUSION

In this study, we demonstrated that IL-22 is a survival factor for hepatocytes and prevents and repairs liver injury by enhancing pro-growth pathways via STAT3 activation. Treatment with IL-22 protein may represent a novel therapeutic strategy for preventing liver injury in patients with liver disease who have undergone hepatectomy.

Therapeutic Role of Interleukin 22 in Experimental Intra-abdominal Klebsiella pneumoniae Infection in Mice

Interleukin 22 (IL-22) is an IL-10-related cytokine produced by T helper 17 (Th17) cells and other immune cells that signals via IL-22 receptor alpha 1 (IL-22Ra1), which is expressed on epithelial tissues, as well as hepatocytes. IL-22 has been shown to have hepatoprotective effects that are mediated by signal transducer and activator of transcription 3 (STAT3) signaling. However, it is unclear whether IL-22 can directly regulate antimicrobial programs in the liver. To test this hypothesis, hepatocyte-specific IL-22Ra1 knockout (Il22Ra1(Hep-/-)) and Stat3 knockout (Stat3(Hep-/-)) mice were generated and subjected to intra-abdominal infection with Klebsiella pneumoniae, which results in liver injury and necrosis. We found that overexpression of IL-22 or therapeutic administration of recombinant IL-22 (rIL-22), given 2 h postinfection, significantly reduced the bacterial burden in both the liver and spleen. The antimicrobial activity of rIL-22 required hepatic Il22Ra1 and Stat3. Serum from rIL-22-treated mice showed potent bacteriostatic activity against K. pneumoniae, which was dependent on lipocalin 2 (LCN2). However, in vivo, rIL-22-induced antimicrobial activity was only partially reduced in LCN2-deficient mice. We found that rIL-22 also induced serum amyloid A2 (SAA2) and that SAA2 had anti-K. pneumoniae bactericidal activity in vitro. These results demonstrate that IL-22, through IL-22Ra1 and STAT3 singling, can induce intrinsic antimicrobial activity in the liver, which is due in part to LCN2 and SAA2. Therefore, IL-22 may be a useful adjunct in treating hepatic and intra-abdominal infections.

Th22 cell accumulation is associated with colorectal cancer development

AIM

To investigate the expression of Th22 cells and related cytokines in colorectal cancer (CRC) tissues, and the probably mechanism.

METHODS

CRC tumor and paratumor tissues were collected to detect the expression levels of Th22 cells and of related cytokines by immunohistochemistry, flow cytometry and real-time quantitative polymerase chain reaction (RT-qPCR). Interleukin (IL)-22 alone or with a STAT3 inhibitor was co-cultured with RKO cells in vitro to study the effects of IL-22 on colon cancer cells. IL-22 alone or with a STAT3 inhibitor was injected into a BALB/c nude mouse model with subcutaneously transplanted RKO cells to study the effects of IL-22 on colon cancer growth.

RESULTS

The percentage of Th22 cells in the CD4(+) T subset was significantly higher in tumor tissues compared with that in paratumor tissues (1.47% ± 0.083% vs 1.23% ± 0.077%, P < 0.05) as determined by flow cytometry. RT-qPCR analysis revealed that the mRNA expression levels of IL-22, aryl hydrocarbon receptor, CCL20 and CCL22 were significantly higher in tumor tissues compared with those in paratumor tissues. CCL27 mRNA also displayed a higher expression level in tumor tissues compared with that in paratumor tissues; however, these levels were not significantly different (2.58 ± 0.93 vs 2.30 ± 0.78, P > 0.05). IL-22 enhanced colon cancer cell proliferation in vitro and displayed anti-apoptotic effects; these effects were blocked by adding a STAT3 inhibitor. IL-22 promoted tumor growth in BALB/c nude mice; however, this effect was reversed by adding a STAT3 inhibitor.

CONCLUSION

Th22 cells that accumulate in CRC may be associated with the chemotactic effect of the tumor microenvironment. IL-22 is associated with CRC development, most likely via STAT3 activation.

rIL-22 as an adjuvant enhances the immunogenicity of rGroEL in mice and its protective efficacy against S. Typhi and S. Typhimurium

Salmonella infection, ranging from mild, self-limiting diarrhea to severe gastrointestinal, septicemic disease and enteric fever, is a global health problem both in humans and animals. Rapid development of microbial drug resistance has led to a need for efficacious and affordable vaccines against Salmonella. Microbial heat shock proteins (HSPs), including HSP60 and HSP70, are the dominant antigens that promote the host immune response. Co-administration of these antigens with cytokines, such as IL-22, which plays an important role in antimicrobial defense, can enhance the immune response and protection against pathogens. Therefore, the aim of the present study was to determine the immunogenicity of rGroEL (Hsp60) of S. Typhi, alone or administered in combination with murine rIL-22, and its protective efficacy against lethal infection with Salmonella, in mice. There was appreciable stimulation of the humoral and cell-mediated immune responses in mice immunized with rGroEL alone. However, co-administration of rGroEL with rIL-22 further boosted the antibody titers (IgG, IgG1 and IgG2a), T-cell proliferative responses and the secretion of both Th1 and Th2 cytokines. Additionally, rGroEL alone accorded 65%-70% protection against lethal challenge with S. Typhi and S. Typhimurium, which increased to 90% when co-administered with rIL-22.

Derivation of Phase 3 dosing for peginterferon lambda-1a in chronic hepatitis C, Part 2: Exposure-response analyses for efficacy and safety variables

This is the second of two manuscripts detailing the pharmacodynamic derivation of peginterferon lambda-1a (Lambda) dosing and treatment durations for Phase 3 studies in hepatitis C virus (HCV) infection, based on Phase 2 data. Herein, we describe the derivation of regression models for 12-week on-treatment virologic response and safety outcomes at 120, 180, and 240 μg Lambda with ribavirin. In patients with HCV genotypes 1 or 4, there was a significant (P = 0.024) relationship between undetectable HCV-RNA at Week 4 and Lambda exposure (AUC or Cmax ), with the largest difference between adjacent dose levels between the 180 and 120 μg exposure ranges. Risk of Grade 3-4 aminotransferase or bilirubin elevations relative to a peginterferon alfa-2a/ribavirin control were related to Lambda exposure for all patients, and the largest increase between adjacent dose levels was seen for 240 versus 180 μg. Anemia and neutropenia events were lower than control across all doses and exposures. Based on these data and those in our previous manuscript, Phase 3 studies will evaluate fixed 180 µg doses of Lambda in combination with ribavirin and a direct-acting antiviral for 24-48 weeks in HCV genotypes 1 or 4 or 12-24 weeks in genotypes 2 or 3.

Derivation of Phase 3 dosing for peginterferon lambda-1a in chronic hepatitis C, Part 1: Modeling optimal treatment duration and sustained virologic response rates

Peginterferon lambda-1a (Lambda) is under clinical development for the treatment of chronic hepatitis B and C virus (HBV, HCV, respectively) infection. This is the first of two manuscripts detailing the pharmacodynamic derivation of Lambda dosing and treatment durations for Phase 3 studies in HCV, based on Phase 2 data. We describe here the derivation of a population model of Lambda exposure; the adaptation of a previously published viral dynamic model for Lambda treatment and host genotype, and its use to simulate sustained virologic responses (SVR). Lambda population pharmacokinetics was described by a one-compartment model with first-order absorption, and 33.0 L per day clearance with 47% interindividual (36% intra-individual) variability. Weight explained a negligible proportion of the variability. Based on SVR predictions, optimum treatment durations were 48 weeks for HCV genotypes 1 or 4 (SVR estimates for 120, 180, and 240 μg Lambda: 58%, 54%, 47%, respectively) and 24 weeks for genotypes 2 or 3 (75%, 72%, 67%). SVR predictions for 240 μg were lower due to dropout predictions. The SVR model established the optimum treatment duration for Phase 3 studies but did not differentiate between 120 and 180 μg dosing. A companion manuscript describes dose selection based on exposure-response/safety modeling.

Dynamic and extensive metabolic state-dependent regulation of cytokine expression and circulating levels

Cytokines play diverse and critical roles in innate and acquired immunity, and several function within the central nervous system and in peripheral tissues to modulate energy metabolism. The extent to which changes in energy balance impact the expression and circulating levels of cytokines (many of which have pleiotropic functions) has not been systematically examined. To investigate metabolism-related changes in cytokine profiles, we used a multiplex approach to assess changes in 71 circulating mouse cytokines in response to acute (fasting and refeeding) and chronic (high-fat feeding) alterations in whole body metabolism. Refeeding significantly decreased serum levels of IL-22, IL-1α, soluble (s)IL-2Rα, and soluble vascular endothelial growth factor receptor 3 (VEGFR3), but markedly increased granulocyte colony-stimulating factor (G-CSF), IL-1β, chemokine (C-C motif) ligand (CCL2), sIL-1RI, lipocalin-2, pentraxin-3, tissue inhibitor of metalloproteinase (TIMP-1), and serum amyloid protein (SAP) relative to the fasted state. Interestingly, only a few of these changes paralleled the alterations in expression of their corresponding mRNAs. Functional studies demonstrated that central delivery of G-CSF increased, whereas IL-22 decreased, food intake. Changes in food intake were not accompanied by acute alterations in orexigenic (Npy and Agrp) and anorexigenic (Pomc and Cart) neuropeptide gene expression in the hypothalamus. In the context of chronic high-fat feeding, circulating levels of chemokine (C-X-C) ligand (CXCL1), serum amyloid protein A3 (SAA3), TIMP-1, α1-acid glycoprotein (AGP), and A2M were increased, whereas IL-12p40, CCL4, sCD30, soluble receptor for advanced glycation end products (sRAGE), CCL12, CCL20, CX3CL1, IL-16, IL-22, and haptoglobin were decreased relative to mice fed a control low-fat diet. These results demonstrate that both short- and long-term changes in whole body metabolism extensively alter cytokine expression and circulating levels, thus providing a foundation and framework for further investigations to ascertain the metabolic roles for these molecules in physiological and pathological states.

Viral infection. Prevention and cure of rotavirus infection via TLR5/NLRC4-mediated production of IL-22 and IL-18

Activators of innate immunity may have the potential to combat a broad range of infectious agents. We report that treatment with bacterial flagellin prevented rotavirus (RV) infection in mice and cured chronically RV-infected mice. Protection was independent of adaptive immunity and interferon (IFN, type I and II) and required flagellin receptors Toll-like receptor 5 (TLR5) and NOD-like receptor C4 (NLRC4). Flagellin-induced activation of TLR5 on dendritic cells elicited production of the cytokine interleukin-22 (IL-22), which induced a protective gene expression program in intestinal epithelial cells. Flagellin also induced NLRC4-dependent production of IL-18 and immediate elimination of RV-infected cells. Administration of IL-22 and IL-18 to mice fully recapitulated the capacity of flagellin to prevent or eliminate RV infection and thus holds promise as a broad-spectrum antiviral agent.

In vitro anti-influenza A activity of interferon (IFN)-λ1 combined with IFN-β or oseltamivir carboxylate

Influenza viruses, which can cross species barriers and adapt to new hosts, pose a constant potential threat to human health. The influenza pandemic of 2009 highlighted the rapidity with which an influenza virus can spread worldwide. Currently available antivirals have a number of limitations against influenza, and novel antiviral strategies, including novel drugs and drug combinations, are urgently needed. Here, we evaluated the in vitro effects of interferon (IFN)-β, IFN-λ1, oseltamivir carboxylate (a neuraminidase (NA) inhibitor), and combinations of these agents against two seasonal (i.e., H1N1 and H3N2) influenza A viruses. We observed that A/California/04/09 (H1N1) and A/Panama/2007/99 (H3N2) isolates were equally sensitive to the antiviral activity of IFN-β and oseltamivir carboxylate in A549 and Calu-3 cells. In contrast, IFN-λ1 exhibited substantially lower protective potential against the H1N1 strain (64-1030-fold ↓, P<0.05), and was ineffective against H3N2 virus in both cell lines. Three dimensional analysis of drug-drug interactions revealed that IFN-λ1 interacted with IFN-β and oseltamivir carboxylate in an additive or synergistic manner, respectively, to inhibit influenza A virus replication in human airway epithelial cells. Overall, the present study demonstrated that anti-influenza agents with different mechanisms of action (e.g., a NA inhibitor combined with IFN-λ1) exerted a significantly greater (P<0.05) synergistic effect compared to co-treatment with drugs that target the same signaling pathway (i.e., IFN-β plus IFN-λ1) in vitro. Our findings provide support for the combined use of interferon plus oseltamivir as a potential means for treating influenza infections.

Suppression of hepatocellular carcinoma proliferation and hepatitis B surface antigen secretion with interferon-λ1 or PEG-interferon-λ1

Hepatocellular carcinoma (HCC) is a common cancer associated with chronic hepatitis B virus (HBV) infection. Conventional interferon-α (IFN-α) and pegylated IFNs (PEG-IFNs) approved for chronic HBV infection treatment can reduce the risk of HCC but are not suitable for the majority of patients and cause significant side effects. IFN-λ1 is a type III IFN with antiviral, antiproliferative, and immunomodulatory functions similar to type I IFNs but with fewer side effects. However, the tolerability and antitumor activity of PEG-IFN-λ1 in HCC xenograft mice are unknown. In vitro IFN-λ1 treatment of Hep3B and Huh7 human hepatoma cell lines increased MHC class I expression, activated JAK-STAT signaling pathways, induced IFN-stimulated gene expression, and inhibited hepatitis B surface antigen (HBsAg) expression. IFN-λ1 treatment also caused 23.2 and 19.9% growth inhibition of Hep3B and Huh7 cells, respectively, and promoted cellular apoptosis. PEG-IFN-λ1, but not IFN-λ1 treatment, significantly suppressed tumor growth (P=0.002) and induced tumor cell apoptosis in a Hep3B cell xenograft mouse model without significant weight loss or toxicity. PEG-IFN-λ1 also significantly inhibited (P=0.000) serum HBsAg secretion from Hep3B xenograft tumors in vivo. Thus, PEG-IFN-λ1 can suppress Hep3B xenograft tumor growth and inhibit HBsAg production and may be a potential treatment for HBV-related HCC.

Interleukin-21 and T follicular helper cells in HIV infection: research focus and future perspectives

Interleukin (IL)-21 is a member of the γ chain-receptor cytokine family along with IL-2, IL-4, IL-7, IL-9, and IL-15. The effects of IL-21 are pleiotropic, owing to the broad cellular distribution of the IL-21 receptor. IL-21 is secreted by activated CD4 T cells and natural killer T cells. Within CD4 T cells, its secretion is restricted mainly to T follicular helper (Tfh) cells and Th17 cells to a lesser extent. Our research focus has been on the role of IL-21 and more recently of Tfh in immunopathogenesis of HIV infection. This review focuses on first the influence of IL-21 in regulation of T cell, B cell, and NK cell responses and its immunotherapeutic potential in viral infections and as a vaccine adjuvant. Second, we discuss the pivotal role of Tfh in generation of antibody responses in HIV-infected persons in studies using influenza vaccines as a probe. Lastly, we review data supporting ability of HIV to infect Tfh and the role of these cells as reservoirs for HIV and their contribution to viral persistence.

Adenovirus expressing IFN-λ1 (IL-29) attenuates allergic airway inflammation and airway hyperreactivity in experimental asthma

BACKGROUND

Asthma is thought to result from the generation of T helper type 2 (Th2) responses, leading to bronchial inflammation. IFN-λ1 (also known as IL-29) is a recently described member of the IFN-λ family and has been shown to decrease production of Th2 cytokines in vitro. However, the role and mechanism of IFN-λ1 in asthma remain unknown.

OBJECTIVES

The aim of this study was to clarify the importance of IFN-λ1 in allergen-induced airway hyperresponsiveness (AHR) and inflammation.

METHODS

We used a murine model for ovalbumin (OVA)-induced asthma to examine the effect of intranasal delivery of recombinant adenovirus expressing human IFN-λ1 (Ad-hIFN-λ1) on AHR and allergic airway inflammation.

RESULTS

Intranasal instillation of Ad-hIFN-λ1 before airway antigen challenge in OVA-immunized mice significantly decreased the severity of AHR and numbers of eosinophils and levels of IL-4, IL-5, and IL-13, but not IL-10 and IFN-γ; both in vivo, in the bronchoalveolar lavage fluid and in vitro, following stimulation of lymphocytes from spleens with OVA, compared with administration of a control virus (Ad-mock). Furthermore, Ad-hIFN-λ1 treatment inhibited serum IgE secretion and increased numbers of splenic CD4(+)CD25(+)FOXP3(+) Treg cells. Histological studies showed that Ad-hIFN-λ1 attenuated OVA-induced lung tissue eosinophilia.

CONCLUSIONS

These results demonstrate that delivery of the Ad-hIFN-λ1 can mitigate allergic airway inflammation in experimental asthma. The potent immunoregulatory action of IFN-λ1 may offer a novel therapeutic approach to treat allergic asthma.

Amelioration of Muc5b mucin hypersecretion is enhanced by IL-33 after 2-APB administration in a murine model of allergic rhinitis

We attempted to clarify whether hypersecretion of Muc5b mucin from mouse nasal submucosal glands that is enhanced by interleukin (IL)-33 under allergic conditions can be ameliorated by administration of 2-APB. Immunohistochemistry was used to examine both the distribution of T cells in the nasal mucosa of an allergic rhinitis mouse model and expressions of IL-33 receptor ST2 and Muc5b protein in mouse submucosal gland cells. The amounts of protein and mRNA of Orai1, Muc5b, IL-4, IL-5, IL-13 and IL-33 in mouse nasal lavage fluid (NLF) and nasal mucosa were determined using enzyme-linked immunosorbent assay and real-time reverse transcription-polymerase chain reaction. Expressions of Orai1, Muc5b, IL-4, IL-5, IL-13 and IL-33 were up-regulated in the allergic state and IL-33 increased the levels of Muc5b, IL-4, IL-5 and IL-13, but did not influence proliferation of T cells; however, ST2 was diminished in nasal submucosal gland cells. 2-APB reduced proliferation of T cells and the Orai1 level in the nasal mucosa. It also reduced the concentrations of IL-4, IL-5 and IL-13 in NLF and nasal mucosa, and hypersecretion of Muc5b from glandular cells that was enhanced by IL-33, but did not affect IL-33 production. 2-APB decreased Muc5b mucin hypersecretion from submucosal gland that was enhanced by IL-33 in allergic mice by limiting Ca(2+) release-activated Ca(2+) channel activity in which Orai1 plays a crucial role in the gland cells and/or by controlling channel activation in T cells and proliferation of these cells.

Induction of innate lymphoid cell-derived interleukin-22 by the transcription factor STAT3 mediates protection against intestinal infection

Inhibitors of the transcription factor STAT3 target STAT3-dependent tumorigenesis but patients often develop diarrhea from unknown mechanisms. Here we showed that STAT3 deficiency increased morbidity and mortality after Citrobacter rodentium infection with decreased secretion of cytokines including IL-17 and IL-22 associated with the transcription factor RORγt. Administration of the cytokine IL-22 was sufficient to rescue STAT3-deficient mice from lethal infection. Although STAT3 was required for IL-22 production in both innate and adaptive arms, by using conditional gene-deficient mice, we observed that STAT3 expression in RORγt(+) innate lymphoid cells (ILC3s), but not T cells, was essential for the protection. However, STAT3 was required for RORγt expression in T helper cells, but not in ILC3s. Activated STAT3 could directly bind to the Il22 locus. Thus, cancer therapies that utilize STAT3 inhibitors increase the risk for pathogen-mediated diarrhea through direct suppression of IL-22 from gut ILCs.

IL-33 mediates the expressions of IL-5 and IL-13 in Angiostrongylus cantonensis-infected mice

Angiostrongylus cantonensis is the major cause of human eosinophilic meningoencephalitis. C57BL/6 mice were experimentally infected with 35 infectious larvae. Two groups of infected mice received intraperitoneal injections of mouse IL-33 (1μg) or anti-IL-33 monoclonal antibody (mAb) (10μg) 3days post infection (dpi) and subsequent booster shots of the same dose at 5day intervals. Blood samples from each group were collected weekly for assays. IgE levels were significantly increased in all infected mice. The eosinophil percentage and levels of IL-5 and IL-13 significantly increased in the IL-33-treated group relative to infected but non-treated animals. The level of IL-5 decreased in the mAb-treated group. The severity of eosinophilic meningitis was exacerbated in the IL-33 injected group. Taken together, these results suggest that IL-33 mediates the expressions of IL-5 and IL-13, and plays a crucial role in the pathogenesis of angiostrongylosis.

Application of interleukin-22 mediates protection in experimental acetaminophen-induced acute liver injury

Acetaminophen (APAP, paracetamol)-induced hepatotoxicity, although treatable by timely application of N-acetylcysteine, can be fatal. Because it is among the common causes of acute liver failure in intensive care units and in light of its gradually increasing incidence, the need for novel therapeutic strategies aimed at severe intoxication is apparent. Recently, it has been shown that IL-22, a STAT3-activating cytokine, has the capability to mediate liver protection. Herein, the protective potential of IL-22 in murine APAP-induced hepatotoxicity was assessed. Intravenous administration of prophylactic IL-22 significantly reduced serum alanine aminotransferase levels and histopathologic damage in APAP-induced liver injury, a process that coincided with increased hepatocyte proliferation in vivo. Concomitant gene expression analysis revealed hepatic induction of genes prototypically up-regulated by the IL-22/STAT3 axis, among others suppressor of cytokine signaling-3, lipocalin-2, and α1-antichymotrypsin. Notably, in a translational setting of therapeutic treatment 2 hours after APAP, IL-22 supported protection in the context of suboptimal N-acetylcysteine dosing. IL-22 likewise connected to augmented hepatocyte proliferation in this experimental setting. As detected by analysis of inflammatory cytokine production, systemically applied IL-22 did not display acute immunomodulation/stimulation in otherwise untreated or endotoxemic mice. Those latter observations clearly confirm acute tolerability of systemically applied IL-22. Observations presented altogether suggest that therapeutic IL-22 administration is a conceivable tissue-protective regimen aimed at hard-to-treat patients with severe APAP-induced hepatotoxicity.

Macrophages as IL-25/IL-33-responsive cells play an important role in the induction of type 2 immunity

Type 2 immunity is essential for host protection against nematode infection but is detrimental in allergic inflammation or asthma. There is a major research focus on the effector molecules and specific cell types involved in the initiation of type 2 immunity. Recent work has implicated an important role of epithelial-derived cytokines, IL-25 and IL-33, acting on innate immune cells that are believed to be the initial sources of type 2 cytokines IL-4/IL-5/IL-13. The identities of the cell types that mediate the effects of IL-25/IL-33, however, remain to be fully elucidated. In the present study, we demonstrate that macrophages as IL-25/IL-33-responsive cells play an important role in inducing type 2 immunity using both in vitro and in vivo approaches. Macrophages produced type 2 cytokines IL-5 and IL-13 in response to the stimulation of IL-25/IL-33 in vitro, or were the IL-13-producing cells in mice administrated with exogenous IL-33 or infected with Heligmosomoides bakeri. In addition, IL-33 induced alternative activation of macrophages primarily through autocrine IL-13 activating the IL-4Rα-STAT6 pathway. Moreover, depletion of macrophages attenuated the IL-25/IL-33-induced type 2 immunity in mice, while adoptive transfer of IL-33-activated macrophages into mice with a chronic Heligmosomoides bakeri infection induced worm expulsion accompanied by a potent type 2 protective immune response. Thus, macrophages represent a unique population of the innate immune cells pivotal to type 2 immunity and a potential therapeutic target in controlling type 2 immunity-mediated inflammatory pathologies.

Nuclear receptor NR4A2 orchestrates Th17 cell-mediated autoimmune inflammation via IL-21 signalling

IL-17-producing CD4⁺ T helper 17 (Th17) cells are pathogenic in a range of human autoimmune diseases and corresponding animal models. We now demonstrate that such T cells infiltrating the target organ during the induction of experimental autoimmune encephalomyelitis (EAE) and experimental autoimmune uveoretinitis (EAU) specifically express NR4A2. Further, we reveal a critical involvement of NR4A2 in Th17 cell functions and Th17 cell-driven autoimmune diseases. When NR4A2 expression was blocked with siRNA, full Th17 differentiation was prevented in vitro: although cells expressed the master Th17 regulator, RORγt, they expressed reduced levels of IL-23R and were unable to produce IL-17 and IL-21. Notably, Th17 differentiation in the absence of NR4A2 was restored by exogenous IL-21, indicating that NR4A2 controls full maturation of Th17 cells via autocrine IL-21 signalling. Preventing NR4A2 expression in vivo by systemic treatment with NR4A2-specific siRNA also reduced Th17 effector responses and furthermore protected mice from EAE induction. In addition, the lack of disease was associated with a reduction in autocrine IL-21 production and IL-23R expression. Similar modulation of NR4A2 expression was also effective as an intervention, reversing established autoimmune responses and ameliorating clinical disease symptoms. Thus, NR4A2 appears to control Th17 differentiation and so plays an essential role in the development of Th17-mediated autoimmune disease. As NR4A2 is also upregulated during human autoimmune disease, targeting NR4A2 may provide a new therapeutic approach in treating autoimmune disease.

Interleukin-17 signaling in inflammatory, Kupffer cells, and hepatic stellate cells exacerbates liver fibrosis in mice

BACKGROUND & AIMS

Interleukin (IL)-17 signaling has been implicated in lung and skin fibrosis. We examined the role of IL-17 signaling in the pathogenesis of liver fibrosis in mice.

METHODS

Using cholestatic and hepatotoxic models of liver injury, we compared the development of liver fibrosis in wild-type mice with that of IL-17RA(-/-) mice and of bone marrow chimeric mice devoid of IL-17 signaling in immune and Kupffer cells (IL-17RA(-/-) to wild-type and IL-17A(-/-) to wild-type mice) or liver resident cells (wild-type to IL-17RA(-/-) mice).

RESULTS

In response to liver injury, levels of Il-17A and its receptor increased. IL-17A increased appeared to promote fibrosis by activating inflammatory and liver resident cells. IL-17 signaling facilitated production of IL-6, IL-1, and tumor necrosis factor-α by inflammatory cells and increased the expression of transforming growth factor-1, a fibrogenic cytokine. IL-17 directly induced production of collagen type I in hepatic stellate cells by activating the signal transducer and activator of transcription 3 (Stat3) signaling pathway. Mice devoid of Stat3 signaling in hepatic stellate cells (GFAPStat3(-/-) mice) were less susceptible to fibrosis. Furthermore, deletion of IL-23 from immune cells attenuated liver fibrosis, whereas deletion of IL-22 exacerbated fibrosis. Administration of IL-22 and IL-17E (IL-25, a negative regulator of IL-23) protected mice from bile duct ligation-induced liver fibrosis.

CONCLUSIONS

IL-17 induces liver fibrosis through multiple mechanisms in mice. Reagents that block these pathways might be developed as therapeutics for patients with cirrhosis.

Innate lymphoid cells promote anatomical containment of lymphoid-resident commensal bacteria

The mammalian intestinal tract is colonized by trillions of beneficial commensal bacteria that are anatomically restricted to specific niches. However, the mechanisms that regulate anatomical containment remain unclear. Here, we show that interleukin-22 (IL-22)-producing innate lymphoid cells (ILCs) are present in intestinal tissues of healthy mammals. Depletion of ILCs resulted in peripheral dissemination of commensal bacteria and systemic inflammation, which was prevented by administration of IL-22. Disseminating bacteria were identified as Alcaligenes species originating from host lymphoid tissues. Alcaligenes was sufficient to promote systemic inflammation after ILC depletion in mice, and Alcaligenes-specific systemic immune responses were associated with Crohn's disease and progressive hepatitis C virus infection in patients. Collectively, these data indicate that ILCs regulate selective containment of lymphoid-resident bacteria to prevent systemic inflammation associated with chronic diseases.