The Dynamic Role of the IL-33/ST2 Axis in Chronic Viral-infections: Alarming and Adjuvanting the Immune Response

Effects of statins beyond lipid-lowering agents in ART-treated HIV infection

Antiretroviral therapies (ART) have reduced human immunodeficiency virus (HIV) infection-associated morbidity and mortality improving the life of people with HIV (PWH). However, ART lead to residual HIV production, which in conjunction with microbial translocation and immune dysfunction contributes to chronic inflammation and immune activation. PWH on ART remain at an increased risk for cardiovascular diseases (CVDs) including myocardial infarction and stroke; which in part is explained by chronic inflammation and immune activation. Lifestyle factors and certain ART are associated with dyslipidemia characterized by an increase of low-density lipoprotein (LDL), which further contributes in the increased risk for CVDs. Lipid-lowering agents like statins are emerging as immune modulators in decreasing inflammation in a variety of conditions including HIV. The international randomized clinical trial REPRIEVE has shed light on the reduction of CVDs with statin therapy among PWH. Such reports indicate a more than expected benefit of statins beyond their lipid-lowering effects. Bempedoic acid, a first-in-class non-statin LDL-lowering drug with immune modulatory effects, may further aid PWH in combination with statins. Herein, we critically reviewed studies aimed at lipid-lowering and immune-modulating roles of statins that may benefit aging PWH.

IL-33 supplementation improves uterine artery resistance and maternal hypertension in response to placental ischemia

Preeclampsia (PE), a leading cause of maternal/fetal morbidity and mortality, is a hypertensive pregnancy disorder with end-organ damage that manifests after 20 wk of gestation. PE is characterized by chronic immune activation and endothelial dysfunction. Clinical studies report reduced IL-33 signaling in PE. We use the Reduced Uterine Perfusion Pressure (RUPP) rat model, which mimics many PE characteristics including reduced IL-33, to identify mechanisms mediating PE pathophysiology. We hypothesized that IL-33 supplementation would improve blood pressure (BP), inflammation, and oxidative stress (ROS) during placental ischemia. We implanted intraperitoneal mini-osmotic pumps infusing recombinant rat IL-33 (1 µg/kg/day) into normal pregnant (NP) and RUPP rats from gestation day 14 to 19. We found that IL-33 supplementation in RUPP rats reduces maternal blood pressure and improves the uterine artery resistance index (UARI). In addition to physiological improvements, we found decreased circulating and placental cytolytic Natural Killer cells (cNKs) and decreased circulating, placental, and renal TH17s in IL-33-treated RUPP rats. cNK cell cytotoxic activity also decreased in IL-33-supplemented RUPP rats. Furthermore, renal ROS and placental preproendothelin-1 (PPET-1) decreased in RUPP rats treated with IL-33. These findings demonstrate a role for IL-33 in controlling vascular function and maternal BP during pregnancy by decreasing inflammation, renal ROS, and PPET-1 expression. These data suggest that IL-33 may have therapeutic potential in managing PE.NEW & NOTEWORTHY Though decreased IL-33 signaling has been clinically associated with PE, the mechanisms linking this signaling pathway to overall disease pathophysiology are not well understood. This study provides compelling evidence that mechanistically links reduced IL-33 with the inflammatory response and vascular dysfunction observed in response to placental ischemia, such as in PE. Data presented in this study submit the IL-33 signaling pathway as a possible therapeutic target for the treatment of PE.

Plasma IL-33 levels and immune activation in HIV-TB coinfection: a cross-sectional study in Yaoundé, Cameroon

Introduction

HIV-1 and Mtb are characterized by immune activation and unbalances production of cytokines, but the expression of IL33 in HIV/TB coinfection remain understudied. This study aimed to evaluate the level of IL-33 in plasma of HIV and M. tuberculosis (HIV/TB) coinfected patients compared to patients with respective mono infections in Yaoundé.

Methods

a cross-sectional study was conducted among patients attending the pneumology service and HIV treatment center of the Yaoundé Jamot Hospital. Plasma samples of 157 HIV/TB coinfected patients (n =26, 50% males and 50% females, mean age 39), HIV-1 monoinfected patients (n = 41, 41% males and 59% females, mean age 35), TB monoinfected patients (n = 48, 56% males and 44% females, mean age 37) and healthy controls (n = 42, 29% males and 71% females, mean age 32) were examined by enzyme-linked immunoassay (ELISA) to detect the levels of IL-33 cytokine.

Results

plasma level of IL-33 were higher in HIV/TB coinfected (33.1±30.9 pg/ml) and TB monoinfected individuals (15.1±2.9 pg/ml) compared to healthy controls (14.0±3.4 pg/ml) and could not be detected in most of the HIV-1 monoinfected individuals (12.6±8.7 pg/ml). Interestingly, the increased plasma level of IL-33 in HIV/TB coinfected patients showed a statistically significant difference between healthy controls (33.1±30.9 pg/ml vs 14.0±3.4 pg/ml, P<0.0001) and HIV-1 monoinfected patients (33.1±30.9 pg/ml vs 12.6±8.7 pg/ml, P=0.0002). We further found that IL-33 was higher in patients with high viral load group (40.6±59.7 pg/ml vs 12.6±1.8 pg/ml), P= 0.47) whereas patients under highly active antiretroviral therapy (HAART) showed decreased level of IL-33 concentration as the number of years under ART increased. Our data showed a positive association between plasma IL-33 and viral load in the context of HIV/TB coinfection in our study population with a positive Pearson coefficient of r=0.21.

Conclusion

this study indicates that plasma level of IL-33 differs among HIV/TB coinfected patients and respective monoinfections patients. The increased level of plasma IL-33 reveals that IL-33 measurement in HIV-1 monoinfected patients may represent an early predictor of development of tuberculosis.

NLRP3 inhibition improves maternal hypertension, inflammation, and vascular dysfunction in response to placental ischemia

Preeclampsia (PE) is a pregnancy-specific hypertensive disorder with end-organ damage that presents after 20 wk of gestation. PE pathophysiology often includes vascular dysfunction and increased inflammation that continues to damage patient health even after PE resolves. Currently, there is no cure for PE beyond delivery of the fetal-placental unit. Previous clinical studies have identified elevated placental NLRP3 expression in patients with PE and suggest NLRP3 as a potential therapeutic target. In this study, we examined the effect of NLRP3 inhibition on PE pathophysiology in the reduced uterine perfusion pressure (RUPP) model rat using MCC950 (20 mg/kg/day) or esomeprazole (3.5 mg/kg/day). We hypothesized that increased NLRP3 in response to placental ischemia impairs anti-inflammatory IL-33 signaling to induce T-helper 17 cell (TH17) and cytolytic NK cell (cNK) activation, which is known to mediate oxidative stress and vascular dysfunction leading to maternal HTN and intrauterine growth restriction. RUPP rats had significantly higher placental NLRP3 expression, maternal blood pressure, fetal reabsorption rate, vascular resistance, oxidative stress, cNKs and TH17s, and decreased IL-33 compared with normal pregnant (NP) rats. NLRP3 inhibition, with either treatment, significantly reduced placental NLRP3 expression, maternal blood pressure, fetal reabsorption rates, vascular resistance, oxidative stress, cNK, and TH17 populations in RUPP rats. Based on our findings, NLRP3 inhibition reduces PE pathophysiology and esomeprazole may be a potential therapeutic for PE treatment.

Epithelial cell alarmin cytokines: Frontline mediators of the asthma inflammatory response

The exposure of the airway epithelium to external stimuli such as allergens, microbes, and air pollution triggers the release of the alarmin cytokines IL-25, IL-33 and thymic stromal lymphopoietin (TSLP). IL-25, IL-33 and TSLP interact with their ligands, IL-17RA, IL1RL1 and TSLPR respectively, expressed by hematopoietic and non-hematopoietic cells including dendritic cells, ILC2 cells, endothelial cells, and fibroblasts. Alarmins play key roles in driving type 2-high, and to a lesser extent type 2-low responses, in asthma. In addition, studies in which each of these three alarmins were targeted in allergen-challenged mice showed decreased chronicity of type-2 driven disease. Consequently, ascertaining the mechanism of activity of these upstream mediators has implications for understanding the outcome of targeted therapies designed to counteract their activity and alleviate downstream type 2-high and low effector responses. Furthermore, identifying the factors which shift the balance between the elicitation of type 2-high, eosinophilic asthma and type-2 low, neutrophilic-positive/negative asthma by alarmins is essential. In support of these efforts, observations from the NAVIGATOR trial imply that targeting TSLP in patients with tezepelumab results in reduced asthma exacerbations, improved lung function and control of the disease. In this review, we will discuss the mechanisms surrounding the secretion of IL-25, IL-33, and TSLP from the airway epithelium and how this influences the allergic airway cascade. We also review in detail how alarmin-receptor/co-receptor interactions modulate downstream allergic inflammation. Current strategies which target alarmins, their efficacy and inflammatory phenotype will be discussed.

Novel Vaccine Strategies and Factors to Consider in Addressing Health Disparities of HPV Infection and Cervical Cancer Development among Native American Women

Cervical cancer is the 4th most common type of cancer in women world-wide. Many factors play a role in cervical cancer development/progression that include genetics, social behaviors, social determinants of health, and even the microbiome. The prevalence of HPV infections and cervical cancer is high and often understudied among Native American communities. While effective HPV vaccines exist, less than 60% of 13- to 17-year-olds in the general population are up to date on their HPV vaccination as of 2020. Vaccination rates are higher among Native American adolescents, approximately 85% for females and 60% for males in the same age group. Unfortunately, the burden of cervical cancer remains high in many Native American populations. In this paper, we will discuss HPV infection, vaccination and the cervicovaginal microbiome with a Native American perspective. We will also provide insight into new strategies for developing novel methods and therapeutics to prevent HPV infections and limit HPV persistence and progression to cervical cancer in all populations.

Host and Microbiome Interplay Shapes the Vaginal Microenvironment

The female reproductive tract harbors a unique microbiome, especially the vagina. The human vaginal microbiome exhibits a low diversity and is dominated by Lactobacillus species, compared to the microbiome of other organs. The host and vaginal microbiome mutually coexist in the vaginal microenvironment. Host cells provide Lactobacillus glycogen as an energy source, and Lactobacillus produce lactic acid, which lowers vaginal pH thereby preventing growth of other bacteria. Bacterial vaginosis can modulate host immune systems, and is frequently associated with various aspects of disease, including sexually transmitted infection, gynecologic cancer, and poor pregnancy outcomes. Because of this, numerous studies focused on the impact of the vaginal microbiome on women`s health and disease. Furthermore, numerous epidemiologic studies also have demonstrated various host factors regulate the vaginal microbiome. The female reproductive tract undergoes constant fluctuations due to hormonal cycle, pregnancy, and other extrinsic factors. Depending on these fluctuations, the vaginal microbiome composition can shift temporally and dynamically. In this review, we highlight the current knowledge of how host factors modulate vaginal microbiome composition and how the vaginal microbiome contributes to maintaining homeostasis or inducing pathogenesis. A better understanding of relationship between host and vaginal microbiome could identify novel targets for diagnosis, prognosis, or treatment of microbiome-related diseases.

CD8+ T Cells in SARS-CoV-2 Induced Disease and Cancer-Clinical Perspectives

Dysregulated innate and adaptive immunity is a sign of SARS-CoV-2-induced disease and cancer. CD8+ T cells are important cells of the immune system. The cells belong to the adaptive immunity and take a front-line defense against viral infections and cancer. Extreme CD8+ T-cell activities in the lung of patients with a SARS-CoV-2-induced disease and within the tumor microenvironment (TME) will change their functionality into exhausted state and undergo apoptosis. Such diminished immunity will put cancer cases at a high-risk group for SARS-CoV-2-induced disease, rendering viral sepsis and a more severe condition which will finally cause a higher rate of mortality. Recovering responses from CD8+ T cells is a purpose of vaccination against SARS-CoV-2. The aim of this review is to discuss the CD8+ T cellular state in SARS-CoV-2-induced disease and in cancer and to present some strategies for recovering the functionality of these critical cells.

The Merkel Cell Polyomavirus T-Antigens and IL-33/ST2-IL1RAcP Axis: Possible Role in Merkel Cell Carcinoma

Merkel cell polyomavirus (MCPyV) is a causal factor in Merkel cell carcinoma (MCC). The oncogenic potential is mediated through its viral oncoproteins large T-antigen (LT) and small T-antigen (sT). Cytokines produced by tumor cells play an important role in cancer pathogenesis, and viruses affect their expression. Therefore, we compared human cytokine and receptor transcript levels in virus positive (V+) and virus negative (V−) MCC cell lines. Increased expression of IL-33, a potent modulator of tumor microenvironment, was observed in V+ MCC cell lines when compared to V− MCC-13 cells. Transient transfection studies with luciferase reporter plasmids demonstrated that LT and sT stimulated IL-33, ST2/IL1RL1 and IL1RAcP promoter activity. The induction of IL-33 expression was confirmed by transfecting MCC-13 cells with MCPyV LT. Furthermore, recombinant human cytokine domain IL-33 induced activation of MAP kinase and NF-κB pathways, which could be blocked by a ST2 receptor antibody. Immunohistochemical analysis demonstrated a significantly stronger IL-33, ST2, and IL1RAcP expression in MCC tissues compared to normal skin. Of interest, significantly higher IL-33 and IL1RAcP protein levels were observed in MCC patient plasma compared to plasma from healthy controls. Previous studies have demonstrated the implication of the IL-33/STL2 pathway in cancer. Because our results revealed a T-antigens-dependent induction of the IL-33/ST2 axis, IL-33/ST2 may play a role in the tumorigenesis of MCPyV-positive MCC. Therefore, neutralizing the IL-33/ST2 axis may present a novel therapeutic approach for MCC patients.

Effect of the COVID-19 Lockdown on Asthma Biological Rhythms

Asthma has a striking temporal character, in which time-of-day, patient age, and season each influence disease activity. The extent to which rhythms in asthma activity reflect exposure to specific disease triggers remains unclear. In this study, we examined how virus mitigation strategies enacted during the COVID-19 pandemic ("lockdown measures") affected rhythms in asthma clinical activity in children. To this end, we retrospectively analyzed asthma clinical presentations in children aged <18 years to our regional academic medical center, comparing 4 years of medical records prior to COVID-19 lockdown measures with the 12 months immediately after the institution of such measures. We correlated these data to positive viral test results, febrile seizures, and allergic clinical surrogates (allergic reaction visits and Emergency Department [ED] antihistamine prescriptions, respectively) over the same time frame. In the 12 months following the institution of the COVID-19 lockdown, positivity rates for common respiratory viruses dropped by 70.2% and ED visits for asthma among children dropped by 62% compared to pre-COVID years. Lockdown suppressed seasonal variation in positive viral tests and asthma ED visits, while diurnal rhythms in asthma visits were unchanged. Asthma seasonality correlated most strongly with rhinovirus positivity both before and after the institution of COVID lockdown measures. Altogether, our data support a causal role for viruses in driving seasonal variability in asthma exacerbations in children.

COVID-19 and Lung Mast Cells: The Kallikrein-Kinin Activation Pathway

Mast cells (MCs) have relevant participation in inflammatory and vascular hyperpermeability events, responsible for the action of the kallikrein-kinin system (KKS), that affect patients inflicted by the severe form of COVID-19. Given a higher number of activated MCs present in COVID-19 patients and their association with vascular hyperpermeability events, we investigated the factors that lead to the activation and degranulation of these cells and their harmful effects on the alveolar septum environment provided by the action of its mediators. Therefore, the pyroptotic processes throughout caspase-1 (CASP-1) and alarmin interleukin-33 (IL-33) secretion were investigated, along with the immunoexpression of angiotensin-converting enzyme 2 (ACE2), bradykinin receptor B1 (B1R) and bradykinin receptor B2 (B2R) on post-mortem lung samples from 24 patients affected by COVID-19. The results were compared to 10 patients affected by H1N1pdm09 and 11 control patients. As a result of the inflammatory processes induced by SARS-CoV-2, the activation by immunoglobulin E (IgE) and degranulation of tryptase, as well as Toluidine Blue metachromatic (TB)-stained MCs of the interstitial and perivascular regions of the same groups were also counted. An increased immunoexpression of the tissue biomarkers CASP-1, IL-33, ACE2, B1R and B2R was observed in the alveolar septum of the COVID-19 patients, associated with a higher density of IgE+ MCs, tryptase+ MCs and TB-stained MCs, in addition to the presence of intra-alveolar edema. These findings suggest the direct correlation of MCs with vascular hyperpermeability, edema and diffuse alveolar damage (DAD) events that affect patients with a severe form of this disease. The role of KKS activation in events involving the exacerbated increase in vascular permeability and its direct link with the conditions that precede intra-alveolar edema, and the consequent DAD, is evidenced. Therapy with drugs that inhibit the activation/degranulation of MCs can prevent the worsening of the prognosis and provide a better outcome for the patient.

Elevated Levels of IL-33, IL-17 and IL-25 Indicate the Progression from Chronicity to Hepatocellular Carcinoma in Hepatitis C Virus Patients

Hepatitis C virus (HCV) is one of the most epidemic viral infections in the world. Three-quarters of individuals infected with HCV become chronic. As a consequence of persistent inflammation, a considerable percentage of chronic patients progress to liver fibrosis, cirrhosis, and finally hepatocellular carcinoma. Cytokines, which are particularly produced from T-helper cells, play a crucial role in immune protection against HCV and the progression of the disease as well. In this study, the role of interleukins IL-33, IL-17, and IL-25 in HCV patients and progression of disease from chronicity to hepatocellular carcinoma will be characterized in order to use them as biomarkers of disease progression. The serum levels of the tested interleukins were measured in patients suffering from chronic hepatitis C (CHC), hepatocellular carcinoma (HCC), and healthy controls (C), and their levels were correlated to the degree of liver fibrosis, liver fibrosis markers and viral load. In contrast to the IL-25 serum level, which increased in patients suffering from HCC only, the serum levels of both IL-33 and IL-17 increased significantly in those patients suffering from CHC and HCC. In addition, IL-33 serum level was found to increase by liver fibrosis progression and viral load, in contrast to both IL-17 and IL-25. Current results indicate a significant role of IL-33 in liver inflammation and fibrosis progress in CHC, whereas IL-17 and IL-25 may be used as biomarkers for the development of hepatocellular carcinoma.

Host-Viral Interactions in the Pathogenesis of Ulcerative Colitis

Ulcerative colitis is characterized by relapsing and remitting colonic mucosal inflammation. During the early stages of viral infection, innate immune defenses are activated, leading to the rapid release of cytokines and the subsequent initiation of downstream responses including inflammation. Previously, intestinal viruses were thought to be either detrimental or neutral to the host. However, persisting viruses may have a role as resident commensals and confer protective immunity during inflammation. On the other hand, the dysregulation of gut mucosal immune responses to viruses can trigger excessive, pathogenic inflammation. The purpose of this review is to discuss virus-induced innate immune responses that are at play in ulcerative colitis.

Reduced pannexin 1-IL-33 axis function in donor livers increases risk of MRSA infection in liver transplant recipients

Liver transplantation patients are at increased risk for methicillin-resistant Staphylococcus aureus (MRSA) infection, but the molecular mechanism remains unclear. We found that genetic predisposition to low pannexin 1 (PANX1) expression in donor livers was associated with MRSA infection in human liver transplantation recipients. Using Panx1 and Il-33-knockout mice for liver transplantation models with MRSA tail vein injection, we demonstrated that Panx1 deficiency increased MRSA-induced liver injury and animal death. We found that decreased PANX1 expression in the liver led to reduced release of adenosine triphosphate (ATP) from hepatocytes, which further reduced the activation of P2X2, an ATP-activating P2X receptor. Reduced P2X2 function further decreased the NLRP3-mediated release of interleukin-33 (IL-33), reducing hepatic recruitment of macrophages and neutrophils. Administration of mouse IL-33 to Panx1^-/- mice significantly (P = 0.011) ameliorated MRSA infection and animal death. Reduced human hepatic IL-33 protein abundance also associated with increased predisposition to MRSA infection. Our findings reveal that genetic predisposition to reduced PANX1 function increases risk for MRSA infection after liver transplantation by decreasing hepatic host innate immune defense, which can be attenuated by IL-33 treatment.

IL-33 activates mTORC1 and modulates glycolytic metabolism in CD8+ T cells

Interleukin (IL)-33, a member in the IL-1 family, plays a central role in innate and adaptive immunity; however, how IL-33 mediates cytotoxic T-cell regulation and the downstream signals remain elusive. In this study, we found increased mouse IL-33 expression in CD8⁺ T cells following cell activation via anti-CD3/CD28 stimulation in vitro or lymphocytic choriomeningitis virus (LCMV) infection in vivo. Our cell adoptive transfer experiment demonstrated that extracellular, but not nuclear, IL-33 contributed to the activation and proliferation of CD8⁺ , but not CD4⁺ T effector cells in LCMV infection. Importantly, IL-33 induced mTORC1 activation in CD8⁺ T cells as evidenced by increased phosphorylated S6 ribosomal protein (p-S6) levels both in vitro and in vivo. Meanwhile, this IL-33-induced CD8⁺ T-cell activation was suppressed by mTORC1 inhibitors. Furthermore, IL-33 elevated glucose uptake and lactate production in CD8⁺ T cells in both dose- and time-dependent manners. The results of glycolytic rate assay demonstrated the increased glycolytic capacity of IL-33-treated CD8⁺ T cells compared with that of control cells. Our mechanistic study further revealed the capacity of IL-33 in promoting the expression of glucose transporter 1 (Glut1) and glycolytic enzymes via mTORC1, leading to accelerated aerobic glucose metabolism Warburg effect and increased effector T-cell activation. Together, our data provide new insights into IL-33-mediated regulation of CD8⁺ T cells, which might be beneficial for therapeutic strategies of inflammatory and infectious diseases in the future.

Syndemics and preexposure prophylaxis are independently associated with rectal immune dysregulation in sexual minority men

OBJECTIVE

Syndemic conditions have been linked to engagement in receptive condomless anal sex (CAS) and HIV seroconversion. However, little is known about the biological pathways whereby syndemics could amplify vulnerability to HIV and other sexually transmitted infections (STIs).

DESIGN

HIV-negative sexual minority men (i.e. gay, bisexual and other MSM) were recruited from four STI clinics in South Florida for a cross-sectional study.

METHODS

Participants completed assessments for four syndemic conditions: depression, posttraumatic stress disorder, hazardous alcohol use and any stimulant use (i.e. any self-reported use or reactive urine toxicology results). Cytokine and chemokine levels were measured using LEGENDplex from the rectal swabs of 92 participants reporting receptive CAS and no antibiotic use in the past three months.

RESULTS

After controlling for age, race/ethnicity, preexposure prophylaxis (PrEP) use and number of receptive CAS partners, a greater number of syndemic conditions was associated with higher levels of rectal cytokines/chemokines relevant to immune activation, inflammation and the expansion and maintenance of T-helper 17 target cells, including rectal interferon-gamma (β = 0.22; P = 0.047), CXCL-8 (β = 0.24; P = 0.025) and interleukin-23 (β = 0.22; P = 0.049). Elevations in rectal cytokine or chemokine levels were most pronounced among participants experiencing two or more syndemic conditions compared with those experiencing no syndemic conditions. PrEP use was independently associated with elevations in multiple rectal cytokines/chemokines.

CONCLUSION

Syndemic conditions could increase biological vulnerability to HIV and other STIs in sexual minority men by potentiating rectal immune dysregulation.

Role for IL-1 Family Cytokines in Fungal Infections

Fungal pathogens kill approximately 1.5 million individuals per year and represent a severe disease burden worldwide. It is estimated over 150 million people have serious fungal disease such as recurrent mucosal infections or life-threatening systemic infections. Disease can ensue from commensal fungi or new infection and involves different fungal morphologies and the expression of virulence factors. Therefore, anti-fungal immunity is complex and requires coordination between multiple facets of the immune system. IL-1 family cytokines are associated with acute and chronic inflammation and are essential for the innate response to infection. Recent research indicates IL-1 cytokines play a key role mediating immunity against different fungal infections. During mucosal disease, IL-1R and IL-36R are required for neutrophil recruitment and protective Th17 responses, but function through different mechanisms. During systemic disease, IL-18 drives protective Th1 responses, while IL-33 promotes Th2 and suppresses Th1 immunity. The IL-1 family represents an attractive anti-fungal immunotherapy target. There is a need for novel anti-fungal therapeutics, as current therapies are ineffective, toxic and encounter resistance, and no anti-fungal vaccine exists. Furthering our understanding of the IL-1 family cytokines and their complex role during fungal infection may aid the development of novel therapies. As such, this review will discuss the role for IL-1 family cytokines in fungal infections.

Serum-soluble ST2 as a novel biomarker reflecting inflammatory status and illness severity in patients with COVID-19

Aim: The authors studied the role of soluble ST2 (sST2) in COVID-19 and its relationship with inflammatory status and disease severity. Materials & methods: Serum levels of sST2 and interleukin (IL)-33, C-reactive protein (CRP), serum amyloid protein (SAA), IL-6 and procalcitonin (PCT), and T lymphocyte subsets from 80 subjects diagnosed with COVID-19 including 36 mild, 41 severe and three asymptomatic cases were tested. Results: Serum sST2 levels were significantly increased in COVID-19 patients, which were positively correlated with CRP, but negatively correlated with CD4⁺ and CD8⁺ T lymphocyte counts. Serum sST2 levels in nonsurviving severe cases were persistently high during disease progression. Conclusion: Serum sST2 level test is helpful for reflecting inflammatory status and illness severity of COVID-19.

Treating From the Inside Out: Relevance of Fecal Microbiota Transplantation to Counteract Gut Damage in GVHD and HIV Infection

The gastrointestinal (GI) tract is a complex and well-balanced milieu of anatomic and immunological barriers. The epithelial surface of the GI tract is colonized by trillions of microorganisms, known as the gut microbiota, which is considered an “organ” with distinctive endocrine and immunoregulatory functions. Dysregulation of the gut microbiota composition, termed dysbiosis, has been associated with epithelial damage and translocation of microbial products into the circulating blood. Dysbiosis, increased gut permeability and chronic inflammation play a major role on the clinical outcome of inflammatory bowel diseases, graft-vs.-host disease (GVHD) and HIV infection. In this review, we focus on GVHD and HIV infection, conditions sharing gut immune damage leading to dysbiosis. The degree of dysbiosis and level of epithelial gut damage predict poor clinical outcome in both conditions. Emerging interventions are therefore warranted to promote gut microbiota homeostasis and improve intestinal barrier function. Interventions such as anti-inflammatory medications, and probiotics have toxicity and/or limited transitory effects, justifying innovative approaches. Fecal microbiota transplantation (FMT) is one such approach where fecal microorganisms are transferred from healthy donors into the GI tract of the recipient to restore microbiota composition in patients with Clostridium difficile-induced colitis or inflammatory bowel diseases. Preliminary findings point toward a beneficial effect of FMT to improve GVHD and HIV-related outcomes through the engraftment of beneficial donor bacteria, notably those producing anti-inflammatory metabolites. Herein, we critically review the potential for FMT in alleviating dysbiosis and gut damage in patients with GVHD or HIV-infection. Understanding the underlying mechanism by which FMT restores gut function will pave the way toward novel scalable and targeted interventions.

Hepatitis B virus X protein (HBx) promotes ST2 expression by GATA2 in liver cells

At present, most studies on the relationship between hepatitis B virus (HBV) and IL-33/ST2 axis focus on clinical detection, but the underlying molecular mechanisms of HBx and IL-33/ST2 axis regulation and Th cell function regulation have not been explored. In this study, serum samples of patients with chronic hepatitis B (CHB) and HBV-related liver cancer (HBV-HCC), and healthy controls, as well as the supernatant solutions of HL7702-WT, HL7702-NC, and HL7702-HBx cells were collected to detect the content of soluble ST2 (sST2). The contents of Th1 cytokines (TNF-α and TNF-γ) and Th2 cytokines (IL-6 and IL-10) in the supernatant of different co-culture groups were detected. The effects of GATA2 on ST2 promoter transcription were investigated by upregulation or interference with GATA2 expression, dual-luciferase reporting, and ChIP experiments. The combined detection of sST2 and FIB-4 was beneficial to the non-invasive diagnosis of liver fibrosis. HBx promotes sST2 expression in liver cells, upregulates Th2 cell function, and inhibits Th1 cell function through IL-33/ST2 axis. HBx interacts with GATA2 to influence the activity of ST2 promoter. Serum sST2 detection is an invaluable indicator for the assessment of the progress of HBV infectious diseases, and the IL-33/ST2 axis plays an important role in changing the cellular immune function caused by HBV infection.

Comparison of IL-33 and IL-5 family mediated activation of human eosinophils

Eosinophils are the prominent inflammatory cell involved in allergic asthma, atopic dermatitis, eosinophilic esophagitis, and hypereosinophilic syndrome and are found in high numbers in local tissue and/or circulating blood of affected patients. There is recent interest in a family of alarmins, including TSLP, IL-25 and IL-33, that are epithelial-derived and released upon stimulation of epithelial cells. Several genome wide association studies have found SNPs in genes encoding IL-33 to be risk factors for asthma. In two studies examining the direct role of IL-33 in eosinophils, there were differences in eosinophil responses. We sought to further characterize activation of eosinophils with IL-33 compared to activation by other cytokines and chemokines. We assessed IL-33 stimulated adhesion, degranulation, chemotaxis and cell surface protein expression in comparison to IL-3, IL-5, and eotaxin-1 on human eosinophils. Our results demonstrate that IL-33 can produce as potent eosinophil activation as IL-3, IL-5 and eotaxin-1. Thus, when considering specific cytokine targeting strategies, IL-33 will be important to consider for modulating eosinophil function.

Serum levels of interleukin 33 and its receptor ST2 in patients treated with subcutaneous allergen immunotherapy in intermittent allergic rhinitis

Introduction

Interleukin 33 (IL-33) is a pleiotropic cytokine involved in pathological processes in seasonal allergic rhinitis. IL-33 binds to ST2 receptor, which is highly expressed on mast cells and selectively on Th2 cells. Information is lacking on the role of IL-33/ST2 axis in allergen subcutaneous immunotherapy.

Aim of the study

To determine if allergen immunotherapy changes the IL-33/ST2l axis in seasonal allergic rhinitis patients.

Material and methods

40 patients with intermittent allergic rhinitis sensitive to grass and/or tree pollen were studied. Among these, 10 patients were longitudinally assessed in the follow-up visit after completing the first course of immunotherapy. Twenty-two healthy subjects were included as controls. Immunotherapy was applied according to a perennial schedule comprising up-building and maintenance phases. Serum levels of ST2/IL-33 R and IL-33 were measured by ELISA (R&D Systems).

Results

Serum levels of IL-33 significantly rose after the first course of immunotherapy and reached the controls levels. Serum levels of ST2 were comparable before the pollen season and after the first course of immunotherapy.

Conclusions

Increase in serum levels of IL-33 after the first course of immunotherapy may suggest it is too short period to prevent the expected raise in serum IL-33 levels in the pollen season, and longer treatment is required to observe significant changes of this cytokine. ST2 serum levels are independent of immunotherapy and pollen season.

Soluble suppression of tumorigenicity 2 levels are not predictive of non-AIDS events during antiretroviral therapy-mediated viral suppression

: Before initiation of antiretroviral therapy (ART), levels of soluble suppression of tumorigenicity 2 (sST2) were not elevated in people living with HIV who later developed non-AIDS events (including myocardial infarction and stroke), compared with controls. However, higher sST2 levels measured pre-ART were a significant predictor of death while on ART. Future studies should explore the potential of sST2 to serve as a short-term predictor of non-AIDS events during viral suppression.

Interleukin 1 Receptor-Like 1 (IL1RL1) Promotes Airway Bacterial and Viral Infection and Inflammation

Interleukin 1 receptor-like 1 (IL1RL1), also known as suppression of tumorigenicity 2 (ST2), is the receptor for interleukin 33 (IL-33) and has been increasingly studied in type 2 inflammation. An increase in airway IL-33/ST2 signaling in asthma has been associated with eosinophilic inflammation, but little is known about the role of ST2 in neutrophilic inflammation. Airway Mycoplasma pneumoniae and human rhinovirus (HRV) infections are linked to neutrophilic inflammation during acute exacerbations of asthma. However, whether ST2 contributes to M. pneumoniae- and HRV-mediated airway inflammation is poorly understood. The current study sought to determine the functions of ST2 during airway M. pneumoniae or HRV infection. In cultured normal human primary airway epithelial cells, ST2 overexpression (OE) increased the production of neutrophilic chemoattractant IL-8 in the absence or presence of M. pneumoniae or HRV1B infection. ST2 OE also enhanced HRV1B-induced IP-10, a chemokine involved in asthma exacerbations. In the M. pneumoniae-infected mouse model, ST2 deficiency, in contrast to sufficiency, significantly reduced the levels of neutrophils following acute (≤24 h) infection, while in the HRV1B-infected mouse model, ST2 deficiency significantly reduced the levels of proinflammatory cytokines KC, IP-10, and IL-33 in bronchoalveolar lavage (BAL) fluid. Overall, ST2 overexpression in human epithelial cells and ST2 sufficiency in mice increased the M. pneumoniae and HRV loads in cell supernatants and BAL fluid. After pathogen infection, ST2-deficient mice showed a higher level of the host defense protein lactotransferrin in BAL fluid. Our data suggest that ST2 promotes proinflammatory responses (e.g., neutrophils) to airway bacterial and viral infection and that blocking ST2 signaling may broadly attenuate airway infection and inflammation.

Circulating LPS and (1→3)-β-D-Glucan: A Folie à Deux Contributing to HIV-Associated Immune Activation

Immune activation is the driving force behind the occurrence of AIDS and non-AIDS events, and is only partially reduced by antiretroviral therapy (ART). Soon after HIV infection, intestinal CD4+ T cells are depleted leading to epithelial gut damage and subsequent translocation of microbes and/or their products into systemic circulation. Bacteria and fungi are the two most abundant populations of the gut microbiome. Circulating lipopolysaccharide (LPS) and (1→3)-β-D-Glucan (βDG), major components of bacterial and fungal cell walls respectively, are measured as markers of microbial translocation in the context of compromised gut barriers. While LPS is a well-known inducer of innate immune activation, βDG is emerging as a significant source of monocyte and NK cell activation that contributes to immune dysfunction. Herein, we critically evaluated recent literature to untangle the respective roles of LPS and βDG in HIV-associated immune dysfunction. Furthermore, we appraised the relevance of LPS and βDG as biomarkers of disease progression and immune activation on ART. Understanding the consequences of elevated LPS and βDG on immune activation will provide insight into novel therapeutic strategies against the occurrence of AIDS and non-AIDS events.

Increased Expression of sST2 in Early HIV Infected Patients Attenuated the IL-33 Induced T Cell Responses

T cell responses were less functional and persisted in an exhausted state in chronic HIV infection. Even in early phase of HIV infection, the dysfunction of HIV-specific T cells can be observed in rapid progressors, but the underlying mechanisms are not fully understood. Cytokines play a central role in regulating T cell function. In this study, we sought to elucidate whether IL-33/ST2 axis plays roles in the regulation of T cell function in HIV infection. We found that the level of IL-33 was upregulated in early HIV-infected patients compared with that in healthy controls and has a trend associated with disease progression. In vitro study shows that IL-33 promotes the expression of IFN-γ by Gag stimulated CD4+ and CD8+T cells from HIV-infected patients to a certain extent. However, soluble ST2 (sST2), a decoy receptor of IL-33, was also increased in early HIV infected patients, especially in those with progressive infection. We found that anti-ST2 antibodies attenuated the effect of IL-33 to CD4+ and CD8+T cells. Our data indicates that elevated expression of IL-33 in early HIV infection has the potential to enhance the function of T cells, but the upregulated sST2 weakens the activity of IL-33, which may indirectly contribute to the dysfunction of T cells and rapid disease progression. This data broadens the understanding of HIV pathogenesis and provides critical information for HIV intervention.

IL-33 drives the antitumor effects of dendritic cells via the induction of Tc9 cells

Dendritic cell (DC) tumor vaccines exert their antitumor effects through the induction of effector T cells. We recently identified Tc9 cells as a new potent antitumor effector T cell subset. However, approaches to direct DCs to preferably prime antitumor Tc9 cells should be further exploited. Here, we demonstrate that the addition of interleukin (IL)-33 potently promotes the induction of Tc9 cells by DCs in vitro and in vivo. IL-33 treatment also drives the cytotoxic activities of DC-induced Tc9 cells. Notably, IL-33 treatment enhances cell survival and proliferation of DC-primed CD8⁺ T cells. More importantly, the addition of IL-33 during in vitro priming of tumor-specific Tc9 cells by DCs increases the antitumor capability of Tc9 cells. Mechanistic studies demonstrated that IL-33 treatment inhibits exhaustive CD8⁺ T cell differentiation by inhibiting PD-1 and 2B4 expression and increasing IL-2 and CD127 (IL-7 receptor-α, IL-7Rα) expression in CD8⁺ T cells. Finally, the addition of IL-33 further promotes the therapeutic efficacy of DC-based tumor vaccines in the OT-I mouse model. Our study demonstrates the important role of IL-33 in DC-induced Tc9 cell differentiation and antitumor immunity and may have important clinical implications.

Use of (1→3)-β-d-glucan for diagnosis and management of invasive mycoses in HIV-infected patients

People living with HIV (PLHIV) are highly vulnerable to invasive fungal infections (IFIs) due to their immune dysfunction. Diagnosis and treatment of IFIs remain challenging due to the requirement of deep tissue sampling to visualise and culture fungi before initiating treatment. Such techniques are less practical in resource‐limited settings due to their cost and requirement of relatively invasive procedures. Hence, identification of surrogate markers for the early diagnosis and therapeutic monitoring of IFIs is required. Recent studies have shown that (1→3)‐β‐d‐glucan (BDG), a major fungal cell wall antigen, represents a promising soluble marker for the presumptive diagnosis and therapeutic monitoring of IFIs in HIV‐infected patients. Herein, we review findings on the merits of BDG assays in the diagnosis of IFIs and monitoring of antifungal therapies for PLHIV. Conversely to other types of immunocompromised patients, HIV infection is associated with gut damage and subsequent bacterial and fungal translocation leading to elevated BDG plasma levels.

Comprehensive cytokine profiling provides evidence for a multi-lineage Th responses in Guillain Barré Syndrome

Guillain Barré Syndrome (GBS) is one of the commonest acquired immune-mediated neuropathies, often preceded by infections. Although cellular immune responses are shown to substantially account for the pathophysiology of GBS, the precise mechanistic basis of risk and disease course remains enigmatic till date. Cytokines are best known for their abilities to drive cellular immunity and inflammation through their co-ordinated actions. Data obtained from clinical and animal model studies suggest important implications of some of the cytokines in the progression and recovery of GBS. However, these studies were performed on few cytokines and small set of GBS patients, thereby lacking a complete understanding of the patterns of association of cytokines representing Th1, Th2, and Th17 responses with GBS. We studied 65 well-characterized GBS patients and 73 age- and sex-matched healthy controls. A panel of 15 cytokines representing Th1, Th2 and Th17 pathways was assayed using Multiplex Suspension Array platform. Plasma levels of five cytokines were found to be altered in GBS patients compared to healthy control subjects: (i) IL-1β exhibited reduced levels, and (ii) IFN-γ, IL-4, IL-21 and IL-33 were elevated in GBS patients. The most important finding of this study was up-regulated expression of IL-21 and IL-33 in patients with GBS. Given the role of IL-33 as an alarmin, the elevated level of this cytokine provides important indication about a much broader role of cytokines in GBS. This study also provides evidence towards a multi-lineage Th cells (Th1, Th2 and Th17) associated cytokine responses in the pathophysiology of GBS.

Plasma Level of Soluble ST2 in Chronically Infected HIV-1 Patients with Suppressed Viremia

Introduction:

Interleukin-33 (IL-33) is a cell damage-induced alarmin. The plasma concentration of suppression of tumorogenicity (sST2), a surrogate marker of IL-33 production, is a prognostic marker of cardiovascular disease.

Observation:

Recently, we reported that sST2 plasma levels were elevated in early HIV-1 infection and linked to markers of microbial translocation and of T cell activation.

Results:

Here we show that it is not the case in patients with suppressed viremia. Thus, IL-33 plays its alarmin role only during the early phase of the infection.

The influence of gut-decontamination prophylactic antibiotics on acute graft-versus-host disease and survival following allogeneic hematopoietic stem cell transplantation

The intestinal microbiota plays a key role in the pathogenesis of acute graft-versus-host disease (aGVHD). High-dose conditioning regimens given prior to allogeneic hematopoietic stem cell transplantation (aHSCT) modulate the composition of gut microbiota and damage the gut epithelial barrier, resulting in increased systemic inflammation. We assessed whether gut decontamination with antibiotics (ATB) prior to aHSCT influenced the frequency of aGVHD and mortality in 500 patients from two Canadian centers between 2005 and 2012. The rate of grade II-IV aGVHD was higher in the ATB arm compared with the arm without ATB (42% vs 28%; p < 0.001). This difference was mainly driven by a 2-fold higher rate of grade II-IV gastrointestinal aGVHD (GI-GVHD) in the ATB arm compared with the arm without ATB (20.7% vs 10.8%; p = 0.003). Multivariate analyses adjusted for known aGVHD risk factors revealed that more patients in the ATB group developed clinically significant GI-GVHD and liver aGVHD; adjusted odds ratio (aOR) = 1.83; p = 0.023 and aOR = 3.56; p = 0.047, respectively. Importantly, median overall survival (OS) was significantly lower in the group receiving ATB and the OS at 10 y remained decreased in the ATB group; adjusted hazard ratio (aHR) = 1.61 (p < 0.001). Without undermining the role of ATB prophylaxis to prevent infection in aHSCT, we have shown that the use of ATB that targets intestinal bacteria is associated with a more severe aGVHD that involves the GI organs and impacts OS. Prospective studies that evaluate the contribution of bacterial decontamination to aGVHD are warranted.