GAPDH, Interferon γ, and Nitric Oxide: Inhibitors of Coronaviruses

As the COVID-19 pandemic finishes its second year, progress has been made against SARS-CoV-2 with vaccine candidates showing efficacy against this latest coronavirus strain. However, this pandemic presents a unique opportunity to investigate anti-viral therapies given the likely probability of another outbreak. One possible (and perhaps unlikely) therapeutic target could be GAPDH (glyceraldehyde-3-phosphate dehydrogenase). Studies have show that downregulation of GAPDH leads to a decrease in interferon gamma (IFNγ production (which is an important cytokine response against coronaviruses and viruses in general). In this light, the previous coronavirus strain (SARS-CoV) has actually been shown to downregulate GAPDH. Although perhaps better known for its role in glycolysis, GAPDH also plays a role in gene expression of a varied set of genes by binding to their mRNA to affect stability and thereby translation Moreover, GAPDH is also upregulated by nitric oxide (NO), an inhibitor against both SARS-CoV and SARS-CoV-2. Additionally, GAPDH has also been shown to be a negative transcriptional regulator of AT1R (angiotensin II receptor 1), which has been shown to bind ACE2 for eventual endocytosis of the complex implicating GAPDH's potential role in the kinetics of coronavirus entry as well in downstream inflammatory signaling resulting from AT1R activation. Lastly, another important role for GAPDH is its requirement in the assembly of the GAIT complex that is responsible for termination of translation of IFNγ-responsive genes that would be critical for the resolution of any inflammatory response. These observations would imply that sufficient levels of GAPDH are needed for immune responses to function properly during a coronaviral infection. By examining different coronavirus studies, this review explores GAPDH's role as an inhibitor of coronaviruses (at the viral transcriptional level and also as a modulator of gene expression related to inflammation), and its signal transduction links to the IFNγ and NO pathways.

IL-17 Upregulates MCP-1 Expression via Act1 / TRAF6 / TAK1 in Experimental Autoimmune Myocarditis

Myocarditis is a myocardial inflammatory infiltration heterogeneous disease. At present, various interventions are not effective in the treatment of myocarditis. IL-17, an important pro‐inflammatory factor secreted mainly by Th17 cells, can promote the expression of multiple cytokines. MCP-1 is an important cytokine that mediates mononuclear cell infiltration. Studies have found that IL-17 could stimulate the expression of MCP-1 to mediate inflammatory infiltration. But the mechanism by which IL-17 induces MCP-1 expression in experimental autoimmune myocarditis (EAM) remains unclear. The purpose of this study is to establish an EAM model to explore the role of Act1/TRAF6/TAK1 cascade in the induction of MCP-1 by IL-17. In the present study, we found that in EAM, IL-17 could stimulate the expression of MCP-1 by activating Act1/TRAF6/TAK1 cascade. After interfering TAK1 with si-TAK1, myocardial tissue inflammation was greatly alleviated, and both MCP-1 mRNA and protein expression were downregulated. In conclusion, IL-17 can activate AP-1, NF-κB via Act1/TRAF6/TAK1 upregulation of MCP-1 expression in EAM.

Enterocytes, fibroblasts and myeloid cells synergize in anti-bacterial and anti-viral pathways with IL22 as the central cytokine

IL22 is an important cytokine involved in the intestinal defense mechanisms against microbiome. By using ileum-derived organoids, we show that the expression of anti-microbial peptides (AMPs) and anti-viral peptides (AVPs) can be induced by IL22. In addition, we identified a bacterial and a viral route, both leading to IL22 production by T cells, but via different pathways. Bacterial products, such as LPS, induce enterocyte-secreted SAA1, which triggers the secretion of IL6 in fibroblasts, and subsequently IL22 in T cells. This IL22 induction can then be enhanced by macrophage-derived TNFα in two ways: by enhancing the responsiveness of T cells to IL6 and by increasing the expression of IL6 by fibroblasts. Viral infections of intestinal cells induce IFNβ1 and subsequently IL7. IFNβ1 can induce the expression of IL6 in fibroblasts and the combined activity of IL6 and IL7 can then induce IL22 expression in T cells. We also show that IL22 reduces the expression of viral entry receptors (e.g. ACE2, TMPRSS2, DPP4, CD46 and TNFRSF14), increases the expression of anti-viral proteins (e.g. RSAD2, AOS, ISG20 and Mx1) and, consequently, reduces the viral infection of neighboring cells. Overall, our data indicates that IL22 contributes to the innate responses against both bacteria and viruses.

The growth factor/ cytokine midkine may participate to cytokine storm and contribute to the pathogenesis of SARS-CoV-2 infected patients

The current coronavirus disease 2019 (COVID-19) outbreak caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has emerged in Wuhan, China and has rapidly become global challenges, creating major challenges to health systems in almost every country in the world it has turned into a pandemic. COVID-19 poses a risky clinical situation that can range from mild illness to severe respiratory failure requiring admission to intensive care. It is known to cause cytokine storm in some critically ill patients. However, more and more evidence showed that there is a dramatic increase in cytokine levels in patients diagnosed with COVID-19. Midkine (MK) is involved in various physiological and pathological processes, which some of them are desired and beneficial such as controlling tissue repair and antimicrobial effects, but some others are harmful such as promoting inflammation, carcinogenesis and chemo-resistance. Also, MK is expressed in inflammatory cells and released by endothelial cells under hypoxic conditions. Considering all this information, there are strong data that MK, an important cytokine known to increase in inflammatory diseases, may overexpressed in patients who are positive for COVID-19. The overexpression of MK reveals a picture leading to fibrosis in the lung damage. Therefore, questions arise about how the concentration of MK changes in CoVID-19 patients and can we use it as an inflammation biomarker or in the treatment protocol in the future.

Type I IFN exacerbates disease in tuberculosis-susceptible mice by inducing neutrophil-mediated lung inflammation and NETosis

Tuberculosis (TB) is a leading cause of mortality due to infectious disease, but the factors determining disease progression are unclear. Transcriptional signatures associated with type I IFN signalling and neutrophilic inflammation were shown to correlate with disease severity in mouse models of TB. Here we show that similar transcriptional signatures correlate with increased bacterial loads and exacerbate pathology during Mycobacterium tuberculosis infection upon GM-CSF blockade. Loss of GM-CSF signalling or genetic susceptibility to TB (C3HeB/FeJ mice) result in type I IFN-induced neutrophil extracellular trap (NET) formation that promotes bacterial growth and promotes disease severity. Consistently, NETs are present in necrotic lung lesions of TB patients responding poorly to antibiotic therapy, supporting the role of NETs in a late stage of TB pathogenesis. Our findings reveal an important cytokine-based innate immune effector network with a central role in determining the outcome of M. tuberculosis infection.

Tumor Suppressors—HTRA Proteases and Interleukin-12—in Pediatric Asthma and Allergic Rhinitis Patients

Background and objective: Allergy belongs to a group of mast cell-related disorders and is one of the most common diseases of childhood. It was shown that asthma and allergic rhinitis diminish the risk of various cancers, including colon cancer and acute lymphoblastic leukemia. On the other hand, asthma augments the risk of lung cancer and an increased risk of breast cancer in patients with allergy has been observed. Thus, the relation between allergy and cancer is not straightforward and furthermore, its biological mechanism is unknown. The HTRA (high temperature requirement A) proteases promote apoptosis, may function as tumor suppressors and HTRA1 is known to be released by mast cells. Interleukin-12 (Il-12) is an important cytokine that induces antitumor immune responses and is produced mainly by dendritic cells that co-localize with mast cells in superficial organs. Material and methods: In the present study we have assessed with ELISA plasma levels of the HTRA proteins, Il-12, and of the anti-HTRA autoantibodies in children with allergy (40) and in age matched controls (39). Children are a special population, since they usually do not have comorbidities and take not many drugs the processes we want to observe are not influenced by many other factors. Results: We have found a significant increase of HTRA1, 2 and 3, and of the Il-12 levels in the children with atopy (asthma and allergic rhinitis) compared to controls. Conclusion: Our results suggest that the HTRA1–3 and Il-12 levels might be useful in analyzing the pro- and antioncogenic potential in young atopic patients.

Effects of IL-1β-induced ADAMTS-4/-5 and TAK1 on the degradation of cartilage aggrecan in the progression of human osteoarthritis

Objective Interleukin-1β (IL-1β) is a potentially important cytokine involved in several pathological processes of osteoarthritis (OA). It is well known that a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS-4/-5) and transforming growth factor-β activated kinase 1 (TAK1) contribute to the degradation of human OA cartilage aggrecan. The purpose of this study was to investigate the mechanism by which IL-1β induced the expression of ADAMTS-4/-5 and TAK1 in human OA cartilage aggrecan degradation. Methods The pathological changes of cartilage tissues and chondrocytes were observed by histomorphological analysis. OA chondrocytes were isolated from human articular cartilage tissues and stimulated with 10 ng/ml of IL-1β at the per-designed times (24 h, 48 h, 72 h). Expression of ADAMTS-4/-5 and TAK1 in cartilage tissues and chondrocytes were measured using immunohistochemistry (IHC) and Western blot (WB). Results The level of IL-1β in synovial fluid in the normal group was significantly lower than that in OA group. The expression of ADAMTS-4/-5 and TAK1 were simultaneously upregulated in human OA cartilage tissues,and ADAMTS-4 was more positively correlated with TAK1 than ADAMTS-5. Furthermore, the expression of ADAMTS-4/-5 and TAK1 were increased by stimulation with IL-1β in human OA chondrocytes, but no positive correlation was found. Conclusion It is proposed that reducing the expression of ADAMTS-4/-5 in prevention of OA may involve the inhibition of TAK1 activity.

JAK2/STAT3 regulates estrogen-related senescence of bone marrow stem cells

Emerging evidence has indicated that estrogen deficiency contributes to osteoporosis by affecting the level of inflammation. The inflammation microenvironment affects many cellular physiological processes, one of which may be cellular senescence according to previous studies. Senescent cells cannot function normally and secrete inflammatory cytokines and degradative proteins, which are referred to as senescence-associated secretory phenotype (SASP) factors, inducing further senescence and inflammation. Thus, stopping this vicious cycle may be helpful for postmenopausal osteoporosis treatment. Here, we used ovariectomized (OVX) mice as an estrogen-deficient model and confirmed that OVX bone marrow mesenchymal stem cells (BMSCs) displayed a senescent phenotype and upregulated SASP factor secretion both in vitro and in vivo. Furthermore, JAK2/STAT3, an important cytokine secretion-related signalling pathway that is associated with SASP secretion, was activated. Estrogen addition and estrogen receptor blockade confirmed that the JAK2/STAT3 axis participated in OVX BMSC senescence by mediating SASP factors. And JAK inhibition reduced SASP factor expression, alleviated senescence and enhanced osteogenic differentiation. Intraperitoneal injection of a JAK inhibitor, ruxolitinib, prevented bone loss in OVX mice. Collectively, our results revealed that JAK2/STAT3 plays an important role in the inflammation-senescence-SASP feedback loop in OVX BMSCs and that JAK inhibition could be a new method for treating postmenopausal osteoporosis.

IL-4 Augments IL-31/IL-31 Receptor Alpha Interaction Leading to Enhanced Ccl 17 and Ccl 22 Production in Dendritic Cells: Implications for Atopic Dermatitis

Severe pruritus is a characteristic feature of atopic dermatitis (AD) and is closely related to its activity. Recent studies have shown that IL-31 is a key determinant of pruritus in AD. Anti-IL-31 receptor alpha (IL-31RA) antibody treatment has also been reported to improve pruritus clinically, subsequently contributing to the attenuation of AD disease activity. Therefore, IL-31 has been thought to be an important cytokine for regulating pruritus and AD disease activity; however, how IL-31 is involved in the immune response in AD has remained largely unknown. Epidermal Langerhans cells (LCs) and dermal dendritic cells (DCs) derived from bone marrow cells have been reported to play a critical role in AD pathogenesis. LCs and DCs produce Ccl 17 and Ccl 22, which chemoattract Th2 cells, leading to AD development. Therefore, we aimed to clarify how IL-31/IL-31RA interaction affects Ccl 17 and Ccl 22 production. To test this, we analyzed murine bone marrow-derived DCs (BMDCs) stimulated with IL-4, an important cytokine in AD development. We found that IL-31RA expression was upregulated by IL-4 stimulation in a dose-dependent manner in BMDCs. Furthermore, IL-31 upregulates Ccl 17 and Ccl 22 production in the presence of IL-4, whereas IL-31 stimulation alone did not produce Ccl 17 and Ccl 22. These findings suggest that IL-4 mediates IL-31RA expression and IL-31/IL-31RA interaction augments Ccl 17 and Ccl 22 production in BMDCs, which promotes Th2-deviated immune response in AD. Since we previously reported that soybean tar Glyteer, an aryl hydrocarbon receptor (AHR) ligand, impairs IL-4/Stat 6 signaling in BMDCs, we examined whether Glyteer affects IL-31RA expression induced by IL-4 stimulation. Glyteer inhibited upregulation of IL-31RA expression induced by IL-4 stimulation in a dose-dependent manner. Glyteer also inhibited Ccl 17 and Ccl 22 production induced by IL-4 and IL-31 stimulation. Taken together, these findings suggest that Glyteer treatment may improve AD disease activity by impairing IL-31/IL-31RA interaction in DCs.

Topological control of cytokine receptor signaling induces differential effects in hematopoiesis

Although tunable signaling by G protein–coupled receptors can be exploited through medicinal chemistry, a comparable pharmacological approach has been lacking for the modulation of signaling through dimeric receptors, such as those for cytokines. We present a strategy to modulate cytokine receptor signaling output by use of a series of designed C2-symmetric cytokine mimetics, based on the designed ankyrin repeat protein (DARPin) scaffold, that can systematically control erythropoietin receptor (EpoR) dimerization orientation and distance between monomers. We sampled a range of EpoR geometries by varying intermonomer angle and distance, corroborated by several ligand-EpoR complex crystal structures. Across the range, we observed full, partial, and biased agonism as well as stage-selective effects on hematopoiesis. This surrogate ligand strategy opens access to pharmacological modulation of therapeutically important cytokine and growth factor receptor systems.