T Helper Subsets, Peripheral Plasticity, and the Acute Phase Protein, α1-Antitrypsin

Alpha-1-antitrypsin antagonizes COVID-19: a review of the epidemiology, molecular mechanisms, and clinical evidence

Alpha-1-antitrypsin (AAT), a serine protease inhibitor (serpin), is increasingly recognized to inhibit SARS-CoV-2 infection and counter many of the pathogenic mechanisms of COVID-19. Herein, we reviewed the epidemiologic evidence, the molecular mechanisms, and the clinical evidence that support this paradigm. As background to our discussion, we first examined the basic mechanism of SARS-CoV-2 infection and contend that despite the availability of vaccines and anti-viral agents, COVID-19 remains problematic due to viral evolution. We next underscored that measures to prevent severe COVID-19 currently exists but teeters on a balance and that current treatment for severe COVID-19 remains grossly suboptimal. We then reviewed the epidemiologic and clinical evidence that AAT deficiency increases risk of COVID-19 infection and of more severe disease, and the experimental evidence that AAT inhibits cell surface transmembrane protease 2 (TMPRSS2) - a host serine protease required for SARS-CoV-2 entry into cells - and that this inhibition may be augmented by heparin. We also elaborated on the panoply of other activities of AAT (and heparin) that could mitigate severity of COVID-19. Finally, we evaluated the available clinical evidence for AAT treatment of COVID-19.

Th17-Derived Cytokines Synergistically Enhance IL-17C Production by the Colonic Epithelium

Tightly regulated communication between the gastrointestinal epithelium and immune cells in the underlying lamina propria is critical for immune homeostasis and inflammation. IL-17C, produced by epithelial cells after exposure to inflammatory stimuli, facilitates cell-to-cell communication by promoting inflammatory responses in Th17 cells. In this study, we demonstrate that Th17-derived cytokines TNF-α, IL-17A, and IL-22 synergistically enhance IL-17C expression in both human-transformed colonic epithelial cell lines and primary non-inflammatory bowel disease colonic epithelial spheroids. This synergistic expression requires activation of the transcription factor NF-κB downstream of the TNF-α stimulus, evidenced by the reduction of IL-17C expression in the presence of an IκBα inhibitor. IL-17A and IL-22 enhance IL-17C expression through the activation of the transcription factor AP-1 in a p38 MAPK-dependent manner. Colonic spheroids derived from uninvolved epithelial of ulcerative colitis patients stimulated with TNF-α, IL-17A, and IL-22 show muted responses compared with non-inflammatory bowel disease spheroids, and inflamed spheroids yielded more IL-17C expression in the presence of TNF-α, and no response to IL-22 stimulation. Altogether, a role for IL-17C in activating Th17 cells combined with our findings of Th17-derived cytokine-driven synergy in the expression of IL-17C identifies a novel inflammatory amplification loop in the gastrointestinal tract between epithelial cells and Th17 cells.

Insights into the potential role of alpha1-antitrypsin in COVID-19 patients: Mechanisms, current update, and future perspectives

In this work, we provide an up-to-date summary of the available molecular- and cell-related mechanisms by which alpha1-antitrypsin (AAT) protein could be of benefit in treating COVID-19 patients. As well, we demonstrate the current status in terms of the ongoing clinical trials using AAT in COVID-19 patients. Finally, we touch on the potential role gene therapy and stem cell-based gene therapy could have in such emerging and serious condition caused by the SARS-CoV-2 virus.

Update on the pathophysiology of transfusion-related acute lung injury

PURPOSE OF REVIEW

The aim of this study was to discuss recent advances regarding the pathogenesis of transfusion-related acute lung injury (TRALI), which highlight the pathogenic role of macrophages.

RECENT FINDINGS

TRALI remains a leading cause of transfusion-related fatalities, despite the success of the mitigation strategy, and therapeutic approaches are unavailable. Neutrophils (PMNs) are recognized pathogenic cells in TRALI. Macrophages have previously also been suggested to be pathogenic in mice via binding of C5a to their C5a-receptor, producing reactive oxygen species (ROS), which damages the pulmonary endothelium. Recent work has further highlighted the role of macrophages in the TRALI-pathogenesis. It has been shown that the protein osteopontin (OPN) released by macrophages is critical for pulmonary PMN recruitment in mice suffering from TRALI and that targeting OPN prevents the occurrence of TRALI. Another recent study demonstrated the importance of M1-polarized alveolar macrophages in murine TRALI induction by showing that α1-antitrypsin (AAT) overexpression prevented TRALI in mice through decreasing the polarization of alveolar macrophages towards the M1 phenotype.

SUMMARY

Apart from PMNs, macrophages also appear to be important in the pathogenesis of TRALI. Targeting the pathogenic functions of macrophages may be a promising therapeutic strategy to explore in TRALI.

Human-Derived α1-Antitrypsin is Still Efficacious in Heavily Pretreated Patients with Steroid-Resistant Gastrointestinal Graft-versus-Host Disease

Almost one-half of patients developing graft-versus-host disease (GVHD) will not respond to standard first-line steroid treatment. Alpha-1 antitrypsin (AAT) is able to induce tolerance in preclinical models of GVHD. AAT alters the cytokine milieu, promotes a tolerogenic shift of dendritic cells, and skews effector T cells toward regulatory T cells. Gastrointestinal steroid-refractory (SR)-GVHD is a protein-losing enteropathy that might represent the optimal setting in which to use AAT. Here we analyze the outcomes of 16 patients treated with human-derived AAT in advanced-stage gut SR-GVHD, with two-thirds of the patients having failed at least 1 treatment for SR-GVHD. The overall response rate (ORR) was 44%, with a complete response (CR) rate of 27%. Gastrointestinal response was observed in 61% of patients. The median time to best response was 21 days (range, 6 to 26 days). At day 56 after AAT treatment, all CRs were maintained, and the ORR was 39%. The 1-year overall survival was 48% (95% confidence interval, 26% to 74%). Ancillary studies showed that AAT serum levels were in the normal range at the beginning of treatment, whereas fecal loss was elevated. AAT levels consistently rose after exogenous administration, but no correlation was found between serum levels and response. REG3α and IL-33 levels were associated with response while, in contrast to previous reports, regulatory T cells decreased during AAT treatment. This retrospective analysis supports a previous report of AAT as a promising agent in the management of gut SR-GVHD and should prompt its evaluation at an earlier stage.

Venom components of the scorpion Centruroides limpidus modulate cytokine expression by T helper lymphocytes: Identification of ion channel-related toxins by mass spectrometry

The study of the effector mechanisms of T helper cells has revealed different phenotypic characteristics that can be manipulated for designing new therapeutic schemes in different pathological scenarios. Ion channels are significant targets in T lymphocyte modulation since they are closely related to their effector activity. Remarkably, some toxins produced by scorpions specifically affect the function of these membrane proteins. For that reason, these toxins are important candidates in the search for new immunomodulators. Here, the effect of two venom fractions of the scorpion Centruroides limpidus was assessed on T lymphocyte proliferation and cytokine production. The venom fractions ClF8 and ClF9 were separated by reversed-phase high-performance liquid chromatography (RP-HPLC) and cultured at 25 and 35 µg/ml with murine T lymphocytes. The results indicate that the fraction ClF8 increased both production and secretion levels of IFN-γ, IL-4, IL-17A and IL-10 by CD4⁺ T cells at 24 h. In contrast, fraction ClF9 only promoted the secretion of IL-17A and IL-10 at its highest concentration (35 µg/ml). Both fractions did not show any effect on T cell proliferation. Subsequent analyses by liquid chromatography-tandem mass spectrometry (LC-MS/MS) revealed seventeen toxins in the fraction ClF8 and five toxins in the fraction ClF9, most of them with voltage-gated sodium (NaScTx) and potassium (KScTx) channels as molecular targets. These toxins might probably interact with ion channels involved in T lymphocyte activity. Our findings suggest that the difference in composition between the two fractions could be related to the observed effects, and the components identified could be isolated to search for possible immunomodulatory molecules.

M1-polarized alveolar macrophages are crucial in a mouse model of transfusion-related acute lung injury

BACKGROUND

The pathogenesis of transfusion-related acute lung injury (TRALI) progress is incompletely understood, and specific therapies for TRALI are lacking. Alveolar macrophages (AMs) are critical for initiation and resolution of lung inflammation. However, the role of AMs in the pathogenesis of TRALI-associated lung failure is poorly understood.

STUDY DESIGN AND METHODS

Mouse model for in vivo imaging of interleukin (IL)-6 activation in AMs was established by intratracheal instillation of a lentiviral vector carrying the luciferase reporter gene. The TRALI mouse model was produced by intraperitoneal lipopolysaccharide plus intravenous major histocompatibility complex Class I monoclonal antibody treatment. We focused on the changes in AMs in the lung during TRALI and examined whether targeting AMs is an effective strategy to alleviate this condition.

MEASUREMENTS AND MAIN RESULTS

We confirmed that TRALI progress is accompanied by IL-6 activation in AMs. Further study showed that AMs undergo M1 activation during TRALI progress. AM depletion protected mice from TRALI, and transfusion of M1-polarized AMs into 34-1-2 s-treated mice elevated acute lung injury, indicating that the severity of TRALI was able to be ameliorated by targeting AM polarization. Next, we showed that α₁ -antitrypsin (AAT) expression improved lung injury by modulating the production of IL-6 in AMs and decreased polarization of AMs toward the M1 phenotype.

CONCLUSIONS

M1-polarized AMs are crucial in a mouse model of TRALI, and AAT may serve as a future treatment for TRALI by regulating the polarization of AMs.

Methionine enkephalin (MENK) regulates the immune pathogenesis of type 2 diabetes mellitus via the IL-33/ST2 pathway

The incidence and mortality of type 2 diabetes mellitus (T2DM) rank among the top ten worldwide. Emerging studies indicate pathological roles for the immune system in inflammation, insulin resistance and islet β-cell damage in subjects with T2DM. Methionine enkephalin (MENK) is present in endocrine cells of the pancreas and has been suggested to be an important mediator between the immune and neuroendocrine systems. Therefore, it may play a role in modulating insulin secretion from islet cells. Since little is known about the effect of MENK on T2DM, therefore it was the aim of this study to characterize the role and possible mechanism of action of MENK on plasma glucose and serum insulin levels in T2DM rats and INS-1 cells in vivo and in vitro. MENK significantly decreased the plasma glucose level and increased the serum insulin concentration in T2DM rats. It also increased the serum levels of the cytokines IL-5 and IL-10, while decreased TNF-α and IL-2 levels. We further confirmed that MENK regulated glucose metabolism by upregulating opioid receptor expression and modulating the IL-33/ST2 and MyD88-TRAF6-NF-κB p65 signaling pathways. Based on these results, an intraperitoneal injection of MENK represents a potentially new approach for T2DM.

Effectiveness of Antihyperglycemic Effect of Momordica charantia: Implication of T-Cell Cytokines

BACKGROUND/OBJECTIVE

We investigate the effect of antidiabetic Momordica charantia fruit juice on T cells' differentiation, through plasmatic cytokine quantification in type 1 diabetic rats (T1D).

METHODS

Male Wistar rats were rendered diabetic by the injection of five low doses of streptozotocin. Then, animals were treated with Momordica charantia fruit juice for 28 consecutive days. Plasmatic levels of Th1 interleukin- (IL-) 02 and interferon- (IFN-) γ, Th2 (IL-4), and regulatory (IL-10) cytokines were determined in rats.

RESULTS

We observed that fruit juice induced a significant decrease in blood glucose of T1D rats. Besides, the concentrations of IL-2 and IFN-γ significantly increased while those of IL-4 and IL-10 diminished in diabetic rats compared to control animals. Interestingly, after treatment with Momordica charantia fruit juice, IL-4 and IL-10 levels significantly increased in diabetic rats, while IL-2 and IFN-γ concentrations decreased, suggesting a Th2 phenotype in these animals. Phytochemical analysis of the fruit juice revealed the presence of tannins, flavonoids, and coumarins, compounds which possess antioxidant activity.

CONCLUSION

This study shows that Momordica charantia fruit juice, by lowering the hyperglycemia, induced a shift of proinflammatory Th1 phenotype in T1D rats towards a favorable anti-inflammatory Th2 status. These effects might be due to the presence of antioxidant compounds in the juice and confirms the use of this plant in the treatment of autoimmune type 1 diabetes.

Evidence of Immunosuppressive and Th2 Immune Polarizing Effects of Antidiabetic Momordica charantia Fruit Juice

The mechanism of action of the antidiabetic capacity of Momordica charantia is still under investigation. Here, we assessed phytochemical compositions, antioxidant activity, and effects of total and filtered fruit and leafy stem juices of Momordica charantia on human T cell proliferation and differentiation through quantification of Th1/Th2 cytokines. In the absence of stimulation, total fruit and leafy stem juices induced significant T cell proliferation. Under PHA stimulation, both juices potentiated plant-induced T cell proliferation. However, the filtered fruit and leafy stem juices significantly inhibited PHA-stimulated T cell proliferation, while neither juice influenced T cell proliferation. Moreover, total and filtered fruit juice increased IL-4 secretion, while total and filtered leafy stem juice enhanced IFN-γ production. Phytochemical screening revealed the presence of tannins, flavonoids, anthocyans, steroids, and triterpenoids in both juices. Alkaloids, quinone derivatives, cardenolides, and cyanogenic derivatives were undetectable. The saponins present in total juices were undetectable after filtration. Moreover, both juices had appreciable antioxidant capacity. Our study supports the type 1 antidiabetic effect of filtered fruit juice of M. charantia which may be related to its immunosuppressive and T-helper 2 cell inducing capacities. Due to their immune-stimulatory activities and their ability to increase T-helper 1 cell cytokines, total fruit and leafy stem juices may serve in the treatment of immunodeficiency and certain infections.

Altered homeostatic regulation of innate and adaptive immunity in lower gastrointestinal tract GVHD pathogenesis

Lower gastrointestinal (GI) tract graft-versus-host disease (GVHD) is the predominant cause of morbidity and mortality from GVHD after allogeneic stem cell transplantation. Recent data indicate that lower GI tract GVHD is a complicated process mediated by donor/host antigenic disparities. This process is exacerbated by significant changes to the microbiome, and innate and adaptive immune responses that are critical to the induction of disease, persistence of inflammation, and a lack of response to therapy. Here, we discuss new insights into the biology of lower GI tract GVHD and focus on intrinsic pathways and regulatory mechanisms crucial to normal intestinal function. We then describe multiple instances in which these homeostatic mechanisms are altered by donor T cells or conditioning therapy, resulting in exacerbation of GVHD. We also discuss data suggesting that some of these mechanisms produce biomarkers that could be informative as to the severity of GVHD and its response to therapy. Finally, novel therapies that might restore homeostasis in the GI tract during GVHD are highlighted.

Biologics for Targeting Inflammatory Cytokines, Clinical Uses, and Limitations

Proinflammatory cytokines are potent mediators of numerous biological processes and are tightly regulated in the body. Chronic uncontrolled levels of such cytokines can initiate and derive many pathologies, including incidences of autoimmunity and cancer. Therefore, therapies that regulate the activity of inflammatory cytokines, either by supplementation of anti-inflammatory recombinant cytokines or by neutralizing them by using blocking antibodies, have been extensively used over the past decades. Over the past few years, new innovative biological agents for blocking and regulating cytokine activities have emerged. Here, we review some of the most recent approaches of cytokine targeting, focusing on anti-TNF antibodies or recombinant TNF decoy receptor, recombinant IL-1 receptor antagonist (IL-1Ra) and anti-IL-1 antibodies, anti-IL-6 receptor antibodies, and TH17 targeting antibodies. We discuss their effects as biologic drugs, as evaluated in numerous clinical trials, and highlight their therapeutic potential as well as emphasize their inherent limitations and clinical risks. We suggest that while systemic blocking of proinflammatory cytokines using biological agents can ameliorate disease pathogenesis and progression, it may also abrogate the hosts defense against infections. Moreover, we outline the rational need to develop new therapies, which block inflammatory cytokines only at sites of inflammation, while enabling their function systemically.

Modulation of immune cells and Th1/Th2 cytokines in insulin-treated type 2 diabetes mellitus

BACKGROUND

The role of the immune system in insulin resistance associated with type 2 diabetes has been suggested.

OBJECTIVES

We assessed the profile of Th1/Th2 cytokines along with the frequencies of immune cells in insulin-treated type 2 diabetic patients (T2DP).

METHODS

45 T2D patients and 43 age-matched healthy subjects were selected. Serum concentrations of T-helper type 1 (Th1) and Th2 cytokines and the frequencies of innate and adaptive immunity cells were assessed.

RESULTS

T2DP were hyperglycemic and showed high level of insulin, normal levels of triglycerides and total-cholesterol and without any change in HDL-cholesterol.Compared to healthy subjects, T2DP exhibited significant decreased frequencies of neutrophils, without any change in monocytes, eosinophils and natural killer cells. The percentages of total lymphocytes (CD3+) and CD8+-T-cells decreased whereas those of regulatory T-cells increased without any change in CD4+ T-cells in T2DP. Interestingly, the frequencies of effector CD4+-T and B-cells increased in T2DP. Serum concentrations of IL-2, IFN-γ and IL-4 decreased while IL-10 significantly enhanced in T2DP, suggesting a differentiation of CD4+T helper cells towards IL-10-producing-Teff-cells in these patients.

CONCLUSION

Insulin-treated type 2 diabetes is associated with anti-inflammatory profile consistent with differentiation of CD4+-Th-cells towards IL-10-producing-Teff-cells, concomitant with increased frequencies of Treg and B-cells, and this may probably offer prevention against certain infections or autoimmune/inflammatory diseases.