Suppressor of cytokine signaling 4 (SOCS4) protects against severe cytokine storm and enhances viral clearance during influenza infection

miR-1915-3p regulates megakaryocytic and erythroid differentiation by targeting SOCS4

BACKGROUND

Proper control of the lineage bias of megakaryocytic and erythroid progenitor cells (MEPs) is of significant importance, the disorder of which will lead to abnormalities in the number and function of platelets and erythrocytes. Unfortunately, the signaling pathways regulating MEP differentiation largely remain to be elucidated. This study aimed to analyze the role and the underlying molecular mechanism of miR-1915-3p in megakaryocytic and erythroid differentiation.

METHODS

We utilized miRNA mimics and miRNA sponge to alter the expression of miR-1915-3p in megakaryocytic and/or erythroid potential cells; siRNA and overexpression plasmid to change the expression of SOCS4, a potential target of miR-1915-3p. The expression of relevant surface markers was detected by flow cytometry. We scanned for miR-1915-3p target genes by mRNA expression profiling and bioinformatic analysis, and confirmed the targeting by dual-luciferase reporter assay, western blot and gain- and lost-of-function studies. One-way ANOVA and t-test were used to analyze the statistical significance.

RESULTS

In this study, overexpression or knockdown of miR-1915-3p inhibited or promoted erythroid differentiation, respectively. Accordingly, we scanned for miR-1915-3p target genes and confirmed that SOCS4 is one of the direct targets of miR-1915-3p. An attentive examination of the endogenous expression of SOCS4 during megakaryocytic and erythroid differentiation suggested the involvement of SOCS4 in erythroid/megakaryocytic lineage determination. SOCS4 knockdown lessened erythroid surface markers expression, as well as improved megakaryocytic differentiation, similar to the effects of miR-1915-3p overexpression. While SOCS4 overexpression resulted in reversed effects. SOCS4 overexpression in miR-1915-3p upregulated cells rescued the effect of miR-1915-3p.

CONCLUSIONS

miR-1915-3p acts as a negative regulator of erythropoiesis, and positively in thrombopoiesis. SOCS4 is one of the key mediators of miR-1915-3p during the differentiation of MEPs.

Genome-wide identification and characterization of large yellow croaker (Larimichthys crocea) suppressors of cytokine signaling (SOCS) in immune response to Pseudomonas plecoglossicida infection and acute hypoxia stress

The suppressor of cytokine signaling (SOCS) gene family is a group of genes involved in the negative regulation of cytokine signal transduction. The members of this family play a crucial role in regulating immune and inflammatory processes. However, comprehensive investigations of these genes have not yet been conducted in the economically significant fish large yellow croaker (Larimichthys crocea). In this study, a total of 13 SOCS genes (LcSOCS1a, LcSOCS1b, LcSOCS2, LcSOCS3a, LcSOCS3b, LcSOCS4, LcSOCS5a, LcSOCS5b, LcSOCS6, LcSOCS7a, LcSOCS7b, LcCISHa and LcCISHb) were identified and analyzed in L. crocea. The phylogenetic tree revealed a high conservation of SOCS genes in evolution, and the gene structure and motif analysis indicated a high similarity in the structure of LcSOCSs in the same subfamily. In addition, the expression patterns of LcSOCSs showed that LcSOCS1b was significantly down-regulated in all time under acute hypoxia stress, but it was markedly up-regulated throughout the entire process after P. plecoglossicida infection, revealing its different immune effects to two stresses. Besides, LcSOCS2a, LcSOCS6 and LcSOCS7a only participated in acute hypoxic stress, while LcSOCS5a was more sensitive to P. plecoglossicida infection. In summary, these results indicated that SOCS genes were involved in stress responses to both biological and non-biological stimuli, setting the foundation for deeper study on the functions of SOCS genes.

Analysis of alpha-1-antitrypsin (AAT)-regulated, glucocorticoid receptor-dependent genes in macrophages reveals a novel host defense function of AAT

Alpha-1-antitrypsin (AAT) plays a homeostatic role in attenuating excessive inflammation and augmenting host defense against microbes. We demonstrated previously that AAT binds to the glucocorticoid receptor (GR) resulting in significant anti-inflammatory and antimycobacterial consequences in macrophages. Our current investigation aims to uncover AAT-regulated genes that rely on GR in macrophages. We incubated control THP-1 cells (THP-1control) and THP-1 cells knocked down for GR (THP-1GR-KD) with AAT, performed bulk RNA sequencing, and analyzed the findings. In THP-1control cells, AAT significantly upregulated 408 genes and downregulated 376 genes. Comparing THP-1control and THP-1GR-KD cells, 125 (30.6%) of the AAT-upregulated genes and 154 (41.0%) of the AAT-downregulated genes were significantly dependent on GR. Among the AAT-upregulated, GR-dependent genes, CSF-2 that encodes for granulocyte-monocyte colony-stimulating factor (GM-CSF), known to be host-protective against nontuberculous mycobacteria, was strongly upregulated by AAT and dependent on GR. We further quantified the mRNA and protein of several AAT-upregulated, GR-dependent genes in macrophages and the mRNA of several AAT-downregulated, GR-dependent genes. We also discussed the function(s) of selected AAT-regulated, GR-dependent gene products largely in the context of mycobacterial infections. In conclusion, AAT regulated several genes that are dependent on GR and play roles in host immunity against mycobacteria.

Prior infection with unrelated neurotropic virus exacerbates influenza disease and impairs lung T cell responses

Immunity to infectious diseases is predominantly studied by measuring immune responses towards a single pathogen, although co-infections are common. In-depth mechanisms on how co-infections impact anti-viral immunity are lacking, but are highly relevant to treatment and prevention. We established a mouse model of co-infection with unrelated viruses, influenza A (IAV) and Semliki Forest virus (SFV), causing disease in different organ systems. SFV infection eight days before IAV infection results in prolonged IAV replication, elevated cytokine/chemokine levels and exacerbated lung pathology. This is associated with impaired lung IAV-specific CD8+ T cell responses, stemming from suboptimal CD8+ T cell activation and proliferation in draining lymph nodes, and dendritic cell paralysis. Prior SFV infection leads to increased blood brain barrier permeability and presence of IAV RNA in brain, associated with increased trafficking of IAV-specific CD8+ T cells and establishment of long-term tissue-resident memory. Relative to lung IAV-specific CD8+ T cells, brain memory IAV-specific CD8+ T cells have increased TCR repertoire diversity within immunodominant DbNP366+CD8+ and DbPA224+CD8+ responses, featuring suboptimal TCR clonotypes. Overall, our study demonstrates that infection with an unrelated neurotropic virus perturbs IAV-specific immune responses and exacerbates IAV disease. Our work provides key insights into therapy and vaccine regimens directed against unrelated pathogens.

Qingjin Huatan decoction protects mice against influenza a virus pneumonia via the chemokine signaling pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Qingjin Huatan Decoction (QJHTT) consists of 11 herbal medicines: Scutellaria baicalensis Georgi, Gardenia jasminoides J.Ellis, Platycodon grandiflorus (Jacq.) A.DC., Ophiopogon japonicus (Thunb.) Ker Gawl., Morus alba L., Fritillaria thunbergii Miq., Anemarrhena asphodeloides Bunge, Trichosanthes kirilowii Maxim., Citrus reticulata Blanco, Poria cocos (Schw.) Wolf, and Glycyrrhiza uralensis Fisch. As a traditional compound Chinese medicinal formula, QJHTT has been used for more than 400 years in China. Historically, it was used to treat respiratory diseases and had shown beneficial clinical results for diseases related to lung inflammation.

AIM OF THE STUDY

To investigate the therapeutic effect of QJHTT on influenza A virus (IAV) pneumonia in mice and explore its possible mechanism of action.

MATERIALS AND METHODS

The components in QJHTT were analyzed by UPLC-Q-TOF-MS and some antiviral active components reported in the literature were determined and quantified by HPLC. The protective effects of QJHTT were investigated using lethal and sublethal doses (2 LD50 or 0.8 LD50 viral suspension, separately) of H1N1-infected mice. Mortality and lung lesions in H1N1-infected mice were used to evaluate the efficacy of QJHTT. The potential mechanism of QJHTT in the treatment of viral pneumonia was determined at the gene level by RNA sequencing and validated by qRT-PCR. Following this, the changes in protein levels of JAK2/STAT3 were analyzed since it is a key downstream target of the chemokine signaling pathways. Preliminary elucidation of the mechanism of QJHTT to protect mice against IAV pneumonia through this pathway was conducted.

RESULTS

In this study, 12 antiviral active constituents including baicalin, geniposide, and mangiferin were identified from QJHTT. In vivo treatment of QJHTT reduced the virus titers of lung tissue significantly and improved the survival rate, lung index, and pulmonary histopathological changes; additionally, a reduction in the serum levels of TNF-α, IL-1β, IL-6, and IFN-γ inflammatory factors in H1N1-infected mice was observed. RNA-seq analysis and qRT-PCR showed that QJHTT primarily reversed the activities CCL2, CCL7, CCR1, and other chemokines and their reception-related genes, suggesting that QJHTT may produce disease-resistant pneumonia by inhibiting the downstream JAK2/STAT3 pathway. Western blot analysis confirmed that QJHTT effectively reduced the protein levels of JAK2, STAT3, and related phosphorylated products in the lung tissue of H1N1-infected mice.

CONCLUSIONS

Our results indicated that QJHTT alleviated IAV pneumonia in mice by regulating related chemokines and their receptor-related genes in lung tissue, thereby inhibiting JAK2/STAT3 pathway. This could pave way for the design of novel therapeutic strategies to treat viral pneumonia.

SOCSs: important regulators of host cell susceptibility or resistance to viral infection

Suppressors of cytokine signaling (SOCSs) are implicated in viral infection and host antiviral innate immune response. Recent studies demonstrate that viruses can hijack SOCSs to inhibit Janus kinase-signal transducers and activators of transcription (JAK-STAT) pathway, block the production and signaling of interferons (IFNs). At the same time, viruses can hijack SOCS to regulate non-IFN factors to evade antiviral response. Host cells can also regulate SOCSs to resist viral infection. The competition of the control of SOCSs may largely determine the fate of viral infection and the susceptibility or resistance of host cells, which is of significance for development of novel antiviral therapies targeting SOCSs. Accumulating evidence reveal that the regulation and function of SOCSs by viruses and host cells are very complicated, which is determined by characteristics of both viruses and host cell types. This report presents a systematic review to evaluate the roles of SOCSs in viral infection and host antiviral responses. One of messages worth attention is that all eight SOCS members should be investigated to accurately characterize their roles and relative contribution in each viral infection, which may help identify the most effective SOCS to be used in "individualized" antiviral therapy.

Baicalin inhibits influenza A (H1N1)-induced pyroptosis of lung alveolar epithelial cells via caspase-3/GSDME pathway

Baicalin (7-d-glucuronic acid-5, 6-dihydroxyflavone) derived from the root of Scutellaria baicalensis used as Traditional Chinese Medicine (TCM) has been revealed to exert potential antiviral activity via various pathways, while the molecular mechanisms have not been fully understood. Pyroptosis, an inflammatory form of programmed cell death (PCD), is reported to play a crucial role in host cell fate during viral infection. In this study, transcriptome analysis of mice lung tissue reveals that baicalin reverses the alterations of the mRNA levels of PCD-associated genes upon H1N1 challenge, with a concomitant decrease in the population of H1N1-induced propidium iodide (PI)⁺ and Annexin Ⅴ⁺ cells. Intriguingly, we find that baicalin contributes to the survival of infected lung alveolar epithelial cells partly through its inhibition of H1N1-induced cell pyroptosis, which is manifested by reduced bubble-like protrusion cells and lactate dehydrogenase (LDH) release. Moreover, the antipyroptosis effect of baicalin in response to H1N1 infection is found to be mediated by its repression on caspase-3/Gasdermin E (GSDME) pathway. Cleaved caspase-3 and N-terminal fragment of GSDME (GSDME-N) are detected in H1N1-infected cell lines and mice lung tissues, which are markedly reversed by baicalin treatment. Furthermore, inhibition of caspase-3/GSDME pathway by caspase-3 inhibitor or siRNA exerts an antipyroptosis effect equal to that of baicalin treatment in infected A549 and BEAS-2B cells, indicating a pivotal role of caspase-3 in the antiviral activities of baicalin. Conclusively, for the first time, we demonstrate that baicalin could effectively suppress H1N1-induced pyroptosis of lung alveolar epithelial cells via caspase-3/GSDME pathway both in vitro and in vivo.

Altered microRNA Transcriptome in Cultured Human Airway Cells upon Infection with SARS-CoV-2

Numerous proteomic and transcriptomic studies have been carried out to better understand the current multi-variant SARS-CoV-2 virus mechanisms of action and effects. However, they are mostly centered on mRNAs and proteins. The effect of the virus on human post-transcriptional regulatory agents such as microRNAs (miRNAs), which are involved in the regulation of 60% of human gene activity, remains poorly explored. Similar to research we have previously undertaken with other viruses such as Ebola and HIV, in this study we investigated the miRNA profile of lung epithelial cells following infection with SARS-CoV-2. At the 24 and 72 h post-infection time points, SARS-CoV-2 did not drastically alter the miRNome. About 90% of the miRNAs remained non-differentially expressed. The results revealed that miR-1246, miR-1290 and miR-4728-5p were the most upregulated over time. miR-196b-5p and miR-196a-5p were the most downregulated at 24 h, whereas at 72 h, miR-3924, miR-30e-5p and miR-145-3p showed the highest level of downregulation. In the top significantly enriched KEGG pathways of genes targeted by differentially expressed miRNAs we found, among others, MAPK, RAS, P13K-Akt and renin secretion signaling pathways. Using RT-qPCR, we also showed that SARS-CoV-2 may regulate several predicted host mRNA targets involved in the entry of the virus into host cells (ACE2, TMPRSS2, ADAM17, FURIN), renin-angiotensin system (RAS) (Renin, Angiotensinogen, ACE), innate immune response (IL-6, IFN1β, CXCL10, SOCS4) and fundamental cellular processes (AKT, NOTCH, WNT). Finally, we demonstrated by dual-luciferase assay a direct interaction between miR-1246 and ACE-2 mRNA. This study highlights the modulatory role of miRNAs in the pathogenesis of SARS-CoV-2.

Forsythiaside A improves Influenza A virus infection through TLR7 signaling pathway in the lungs of mice

Background

Influenza A virus infection due to drug resistance and side effects of the conventional antiviral drugs yet remains a serious public health threat for humans and animals. Forsythiaside A is an effective ingredient isolated from the Chinese herbal medicine forsythia. It has various pharmacological effects and has a good therapeutic effect against a variety of infectious diseases. This study aimed to further explore the immunological mechanism of Forsythiaside A in the treatment of influenza virus-infected mice and its effect on the Toll-like receptor 7 (TLR7) signaling pathway in the lungs of these mice.

Methods

C57/BL6J mice and TLR7−/− mice were infected with the FM1 strains (H1N1 and A/FM/1/4) of the Influenza A virus. Each group of experimental mice were divided into the mock, virus, oseltamivir, and Forsythiaside A groups. Weight change, lung index change, and the mRNA and protein expression levels of key factors in the TLR7 signaling pathway were detected. Flow cytometry was used to detect the changes in the Th1/Th2 and Th17/Treg ratios.

Results

After infection with the Influenza A virus, the weight loss of C57/BL6J mice treated with forsythoside A and oseltamivir decreased, and the pathological tissue sections showed that the inflammatory damage was reduced. The expression levels of the key factors, TLR7, myeloid differentiation factor 88(Myd88), and nuclear factor-kappa B (NF-κB) in the TLR7 signaling pathway were significantly reduced. Flow cytometry showed that Th1/Th2 and Th17/Treg ratios decreased after Forsythiaside A treatment. In the TLR7−/− mice, there was no significant change after Forsythiaside A treatment in the virus group.

Conclusions

Forsythiaside A affects the TLR7 signaling pathway in mouse lung immune cells and reduces the inflammatory response caused by the Influenza A virus FM1 strain in mouse lungs.

Suppressor of Cytokine Signalling 5 (SOCS5) Modulates Inflammatory Responses during Alphavirus Infection

CNS viral infections are one of the major causes of morbidity and mortality worldwide and a significant global public health concern. Uncontrolled inflammation and immune responses in the brain, despite their protective roles, can also be harmful. The suppressor of cytokine signalling (SOCS) proteins is one of the key mechanisms controlling inflammatory and immune responses across all tissues including the brain. SOCS5 is highly expressed in the brain but there is little understanding of its role in the CNS. Using a mouse model of encephalitis, we demonstrate that lack of SOCS5 results in changes in the pathogenesis and clinical outcome of a neurotropic virus infection. Relative to wild-type mice, SOCS5-deficient mice had greater weight loss, dysregulated cytokine production and increased neuroinflammatory infiltrates composed predominantly of CD11b⁺ cells. We conclude that in the brain, SOCS5 is a vital regulator of anti-viral immunity that mediates the critical balance between immunopathology and virus persistence.

Recent advances in antiviral effects of probiotics: potential mechanism study in prevention and treatment of SARS-CoV-2

SARS-CoV-2 is responsible for coronavirus disease 2019 (COVID-19), progressively extended worldwide countries on an epidemic scale. Along with all the drug treatments suggested to date, currently, there are no approved management protocols and treatment regimens for SARS-CoV-2. The unavailability of optimal medication and effective vaccines against SARS-CoV-2 indicates the requirement for alternative therapies. Probiotics are living organisms that deliberate beneficial effects on the host when used sufficiently and in adequate amounts, and fermented food is their rich source. Probiotics affect viruses by antiviral mechanisms and reduce diarrhea and respiratory tract infection. At this point, we comprehensively evaluated the antiviral effects of probiotics and their mechanism with a particular focus on SARS-CoV-2. In this review, we suggested the conceptual and potential mechanisms of probiotics by which they could exhibit antiviral properties against SARS-CoV-2, according to the previous evidence concerning the mechanism of antiviral effects of probiotics. This study reviewed recent studies that speculate about the role of probiotics in the prevention of the SARS-CoV-2-induced cytokine storm through the mechanisms such as induction of anti-inflammatory cytokines (IL-10), downregulation of pro-inflammatory cytokines (TNF-α, IL-2, IL-6), inhibition of JAK signaling pathway, and act as HDAC inhibitor. Also, the recent clinical trials and their outcome have been reviewed.

Autophagy and Exosome Coordinately Enhance Macrophage M1 Polarization and Recruitment in Influenza A Virus Infection

Background

Influenza A virus infection results in viral pneumonia, which is often accompanied by the infiltration and recruitment of macrophages, overactivation of inflammatory responses, and obvious cell autophagy and exosome production. However, little is known about the roles of autophagy and exosome production in these inflammatory responses.

Methods

In this study, multiple methods, such as flow cytometry, real-time quantitative reverse transcription-polymerase chain reaction, immune–fluorescence technology, and western blot, were applied to explore the possible effects of autophagy and exosome production by H1N1-infected host cells.

Results

It was observed that a high number of polarized macrophages (CD11b⁺/F4/80⁺/CD86⁺) were recruited to the lung tissues of infected mice, which could be mimicked by tracking the movement of macrophages to H1N1-infected cells in vitro (transwell assays). Furthermore, there was some coordinated upregulation of M1 polarization signs (iNOS/Arg-1 bias) as well as autophagy (LC3) and exosome (CD63) biomarkers in the infected macrophages and epithelial cells. Moreover, exosomes extracted from the supernatant of virus-infected cells were shown to promote the recruitment and polarization of more peritoneal macrophages than the normal group. The fluorescence colocalization of LC3-CD63 and the inhibition of autophagy and exosome signaling pathway further revealed that H1N1 infection seemed to sequentially activate the M1 polarization and recruitment of macrophages via autophagy–exosome dependent pathway.

Conclusion

Autophagy and exosome production coordinately enhance the M1 polarization and recruitment of macrophages in influenza virus infection, which also provides potential therapeutic targets.

Functional Analysis of Zebrafish socs4a: Impacts on the Notochord and Sensory Function

The suppressor of cytokine signaling (SOCS) proteins play important roles in cytokine and growth factor signaling, where they act principally as negative feedback regulators, particularly of the downstream signal transducer and activator of transcription (STAT) transcription factors. This critical mode of regulation impacts on both development and homeostasis. However, understanding of the function of SOCS4 remains limited. To address this, we investigated one of the zebrafish SOCS4 paralogues, socs4a, analyzing its expression and the consequences of its ablation. The socs4a gene had a dynamic expression profile during zebrafish embryogenesis, with initial ubiquitous expression becoming restricted to sensory ganglion within the developing nervous system. The knockdown of zebrafish socs4a revealed novel roles in notochord development, as well as the formation of a functional sensory system.

A Randomized, Double-Blind, Placebo-Controlled Study to Assess the Efficacy and Safety of a Nutritional Supplement (ImmuActiveTM) for COVID-19 Patients

Background

SARS-CoV-2 has emerged as a global threat due to its infectivity and rapid transmission. We evaluated the safety and efficacy of herbal and mineral formulation (ImmuActive) as an adjunct therapy in COVID-19 patients.

Methods

A randomized, double-blind, placebo-controlled study was conducted in 100 COVID-19 patients in three centers in Southern India, and 92 subjects completed the study. Subjects were followed up until they were discharged from the hospital or for a maximum of 28 days, whichever was earlier. The primary outcome parameters were the mean change and time required to change the ordinal scale of disease severity by one unit. The secondary outcomes were the time required to turn RT-PCR negative or get discharged from the hospital, change in modified Jackson's Symptom Severity score, and COVID-19 quality of life questionnaire.

Results

The ordinal scale at the end of the study was significantly lower in COVID-19 patients supplemented with ImmuActive (0.57) than placebo (1.0), with a p value of 0.0043. The ordinal scale decreased by one unit within 2.35 days in ImmuActive-supplemented patients, while it took 3.36 days in placebo-supplemented patients. Days of hospitalization and time required to turn RT-PCR negative were comparatively lower in the ImmuActive arm than the placebo arm. Change in modified Jackson's Symptom Severity Score and COVID-19 QOL were significant from screening to the end of the study in both ImmuActive and placebo arms. There were no adverse events observed during the study period.

Conclusion

The study results suggest that ImmuActive could be a beneficial and safe adjunct treatment for effectively managing COVID-19 infection symptoms.

Tpl2 Ablation Leads to Hypercytokinemia and Excessive Cellular Infiltration to the Lungs During Late Stages of Influenza Infection

Tumor progression locus 2 (Tpl2) is a serine-threonine kinase known to promote inflammation in response to various pathogen-associated molecular patterns (PAMPs), inflammatory cytokines and G-protein-coupled receptors and consequently aids in host resistance to pathogens. We have recently shown that Tpl2-/- mice succumb to infection with a low-pathogenicity strain of influenza (x31, H3N2) by an unknown mechanism. In this study, we sought to characterize the cytokine and immune cell profile of influenza-infected Tpl2-/- mice to gain insight into its host protective effects. Although Tpl2-/- mice display modestly impaired viral control, no virus was observed in the lungs of Tpl2-/- mice on the day of peak morbidity and mortality suggesting that morbidity is not due to virus cytopathic effects but rather to an overactive antiviral immune response. Indeed, increased levels of interferon-β (IFN-β), the IFN-inducible monocyte chemoattractant protein-1 (MCP-1, CCL2), Macrophage inflammatory protein 1 alpha (MIP-1α; CCL3), MIP-1β (CCL4), RANTES (CCL5), IP-10 (CXCL10) and Interferon-γ (IFN-γ) was observed in the lungs of influenza-infected Tpl2-/- mice at 7 days post infection (dpi). Elevated cytokine and chemokines were accompanied by increased infiltration of the lungs with inflammatory monocytes and neutrophils. Additionally, we noted that increased IFN-β correlated with increased CCL2, CXCL1 and nitric oxide synthase (NOS2) expression in the lungs, which has been associated with severe influenza infections. Bone marrow chimeras with Tpl2 ablation localized to radioresistant cells confirmed that Tpl2 functions, at least in part, within radioresistant cells to limit pro-inflammatory response to viral infection. Collectively, this study suggests that Tpl2 tempers inflammation during influenza infection by constraining the production of interferons and chemokines which are known to promote the recruitment of detrimental inflammatory monocytes and neutrophils.

SOCS Proteins in Immunity, Inflammatory Diseases, and Immune-Related Cancer

Cytokine signaling represents one of the cornerstones of the immune system, mediating the complex responses required to facilitate appropriate immune cell development and function that supports robust immunity. It is crucial that these signals be tightly regulated, with dysregulation underpinning immune defects, including excessive inflammation, as well as contributing to various immune-related malignancies. A specialized family of proteins called suppressors of cytokine signaling (SOCS) participate in negative feedback regulation of cytokine signaling, ensuring it is appropriately restrained. The eight SOCS proteins identified regulate cytokine and other signaling pathways in unique ways. SOCS1–3 and CISH are most closely involved in the regulation of immune-related signaling, influencing processes such polarization of lymphocytes and the activation of myeloid cells by controlling signaling downstream of essential cytokines such as IL-4, IL-6, and IFN-γ. SOCS protein perturbation disrupts these processes resulting in the development of inflammatory and autoimmune conditions as well as malignancies. As a consequence, SOCS proteins are garnering increased interest as a unique avenue to treat these disorders.

The Emerging Role of Suppressors of Cytokine Signaling (SOCS) in the Development and Progression of Leukemia

Cytokines are pleiotropic signaling molecules that execute an essential role in cell-to-cell communication through binding to cell surface receptors. Receptor binding activates intracellular signaling cascades in the target cell that bring about a wide range of cellular responses, including induction of cell proliferation, migration, differentiation, and apoptosis. The Janus kinase and transducers and activators of transcription (JAK/STAT) signaling pathways are activated upon cytokines and growth factors binding with their corresponding receptors. The SOCS family of proteins has emerged as a key regulator of cytokine signaling, and SOCS insufficiency leads to constitutive activation of JAK/STAT signaling and oncogenic transformation. Dysregulation of SOCS expression is linked to various solid tumors with invasive properties. However, the roles of SOCS in hematological malignancies, such as leukemia, are less clear. In this review, we discuss the recent advances pertaining to SOCS dysregulation in leukemia development and progression. We also highlight the roles of specific SOCS in immune cells within the tumor microenvironment and their possible involvement in anti-tumor immunity. Finally, we discuss the epigenetic, genetic, and post-transcriptional modifications of SOCS genes during tumorigenesis, with an emphasis on leukemia.

Machine learning compensates fold-change method and highlights oxidative phosphorylation in the brain transcriptome of Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disorder causing 70% of dementia cases. However, the mechanism of disease development is still elusive. Despite the availability of a wide range of biological data, a comprehensive understanding of AD's mechanism from machine learning (ML) is so far unrealized, majorly due to the lack of needed data density. To harness the AD mechanism's knowledge from the expression profiles of postmortem prefrontal cortex samples of 310 AD and 157 controls, we used seven predictive operators or combinations of RapidMiner Studio operators to establish predictive models from the input matrix and to assign a weight to each attribute. Besides, conventional fold-change methods were also applied as controls. The identified genes were further submitted to enrichment analysis for KEGG pathways. The average accuracy of ML models ranges from 86.30% to 91.22%. The overlap ratio of the identified genes between ML and conventional methods ranges from 19.7% to 21.3%. ML exclusively identified oxidative phosphorylation genes in the AD pathway. Our results highlighted the deficiency of oxidative phosphorylation in AD and suggest that ML should be considered as complementary to the conventional fold-change methods in transcriptome studies.

Genomic evidence of adaptive evolution in the reptilian SOCS gene family

The suppressor of the cytokine signaling (SOCS) family of proteins play an essential role in inhibiting cytokine receptor signaling by regulating immune signal pathways. Although SOCS gene functions have been examined extensively, no comprehensive study has been performed on this gene family's molecular evolution in reptiles. In this study, we identified eight canonical SOCS genes using recently-published reptilian genomes. We used phylogenetic analysis to determine that the SOCS genes had highly conserved evolutionary dynamics that we classified into two types. We identified positive SOCS4 selection signals in whole reptile lineages and SOCS2 selection signals in the crocodilian lineage. Selective pressure analyses using the branch model and Z-test revealed that these genes were under different negative selection pressures compared to reptile lineages. We also concluded that the nature of selection pressure varies across different reptile lineages on SOCS3, and the crocodilian lineage has experienced rapid evolution. Our results may provide a theoretical foundation for further analyses of reptilian SOCS genes' functional and molecular mechanisms, as well as their roles in reptile growth and development.

Cytokine Storm in COVID-19-Immunopathological Mechanisms, Clinical Considerations, and Therapeutic Approaches: The REPROGRAM Consortium Position Paper

Cytokine storm is an acute hyperinflammatory response that may be responsible for critical illness in many conditions including viral infections, cancer, sepsis, and multi-organ failure. The phenomenon has been implicated in critically ill patients infected with SARS-CoV-2, the novel coronavirus implicated in COVID-19. Critically ill COVID-19 patients experiencing cytokine storm are believed to have a worse prognosis and increased fatality rate. In SARS-CoV-2 infected patients, cytokine storm appears important to the pathogenesis of several severe manifestations of COVID-19: acute respiratory distress syndrome, thromboembolic diseases such as acute ischemic strokes caused by large vessel occlusion and myocardial infarction, encephalitis, acute kidney injury, and vasculitis (Kawasaki-like syndrome in children and renal vasculitis in adult). Understanding the pathogenesis of cytokine storm will help unravel not only risk factors for the condition but also therapeutic strategies to modulate the immune response and deliver improved outcomes in COVID-19 patients at high risk for severe disease. In this article, we present an overview of the cytokine storm and its implications in COVID-19 settings and identify potential pathways or biomarkers that could be targeted for therapy. Leveraging expert opinion, emerging evidence, and a case-based approach, this position paper provides critical insights on cytokine storm from both a prognostic and therapeutic standpoint.

Innate Immune Signaling and Proteolytic Pathways in the Resolution or Exacerbation of SARS-CoV-2 in Covid-19: Key Therapeutic Targets?

COVID-19 is caused by the Severe Acute Respiratory Syndrome (SARS) coronavirus (Cov)-2, an enveloped virus with a positive-polarity, single-stranded RNA genome. The initial outbreak of the pandemic began in December 2019, and it is affecting the human health of the global community. In common with previous pandemics (Influenza H1N1 and SARS-CoV) and the epidemics of Middle east respiratory syndrome (MERS)-CoV, CoVs target bronchial and alveolar epithelial cells. Virus protein ligands (e.g., haemagglutinin or trimeric spike glycoprotein for Influenza and CoV, respectively) interact with cellular receptors, such as (depending on the virus) either sialic acids, Dipeptidyl peptidase 4 (DPP4), or angiotensin-converting enzyme 2 (ACE2). Host proteases, e.g., cathepsins, furin, or members of the type II transmembrane serine proteases (TTSP) family, such as Transmembrane protease serine 2 (TMPRSS2), are involved in virus entry by proteolytically activating virus ligands. Also involved are Toll Like Receptor (TLR) family members, which upregulate anti-viral and pro-inflammatory mediators [interleukin (IL)-6 and IL-8 and type I and type III Interferons among others], through the activation of Nuclear Factor (NF)-kB. When these events (virus cellular entry and innate immune responses) are uncontrolled, a deleterious systemic response is sometimes encountered in infected patients, leading to the well-described "cytokine storm" and an ensuing multiple organ failure promoted by a downregulation of dendritic cell, macrophage, and T-cell function. We aim to describe how the lung and systemic host innate immune responses affect survival either positively, through downregulating initial viral load, or negatively, by triggering uncontrolled inflammation. An emphasis will be put on host cellular signaling pathways and proteases involved with a view on tackling these therapeutically.

O-GlcNAc transferase promotes influenza A virus-induced cytokine storm by targeting interferon regulatory factor-5

In this study, we demonstrated an essential function of the hexosamine biosynthesis pathway (HBP)-associated O-linked β-N-acetylglucosamine (O-GlcNAc) signaling in influenza A virus (IAV)-induced cytokine storm. O-GlcNAc transferase (OGT), a key enzyme for protein O-GlcNAcylation, mediated IAV-induced cytokine production. Upon investigating the mechanisms driving this event, we determined that IAV induced OGT to bind to interferon regulatory factor-5 (IRF5), leading to O-GlcNAcylation of IRF5 on serine-430. O-GlcNAcylation of IRF5 is required for K63-linked ubiquitination of IRF5 and subsequent cytokine production. Analysis of clinical samples revealed that IRF5 is O-GlcNAcylated, and higher levels of proinflammatory cytokines correlated with higher levels of blood glucose in IAV-infected patients. We identified a molecular mechanism by which HBP-mediated O-GlcNAcylation regulates IRF5 function during IAV infection, highlighting the importance of glucose metabolism in IAV-induced cytokine storm.

SOCS3 is a suppressor of γc cytokine signaling and constrains generation of murine Foxp3+ regulatory T cells

SOCS3 is a cytosolic inhibitor of cytokine signaling that suppresses the activation of cytokine receptor-associated JAK kinases. Mechanistically, SOCS3 is recruited to a site in the cytokine receptors known as the SOCS3-interaction motif, and then binds JAK molecules to inhibit their kinase activity. The SOCS3-interaction motif is found in receptors of the gp130 cytokine family but mostly absent from other cytokine receptors, including γc. Thus, SOCS3 has been considered a selective suppressor of gp130 family cytokines, but not γc cytokines. Considering that γc signaling induces SOCS3 expression in T cells, here we revisited the role of SOCS3 on γc signaling. Using SOCS3 transgenic mice, we found that increased abundance of SOCS3 not only suppressed signaling of the gp130 family cytokine IL-6, but also signaling of the γc family cytokine IL-7. Consequently, SOCS3 transgenic mice were impaired in IL-7-dependent T cell development in the thymus and the homeostasis of mature T cells in peripheral tissues. Moreover, enforced SOCS3 expression interfered with the generation of Foxp3⁺ regulatory T cells that requires signaling by the γc family cytokine IL-2. Collectively, we report an underappreciated role for SOCS3 in suppressing γc cytokine signaling, effectively expanding its scope of target cytokines in T cell immunity.

COVID-19: what has been learned and to be learned about the novel coronavirus disease

The outbreak of Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome (SARS) coronavirus 2 (SARS-CoV-2), has thus far killed over 3,000 people and infected over 80,000 in China and elsewhere in the world, resulting in catastrophe for humans. Similar to its homologous virus, SARS-CoV, which caused SARS in thousands of people in 2003, SARS-CoV-2 might also be transmitted from the bats and causes similar symptoms through a similar mechanism. However, COVID-19 has lower severity and mortality than SARS but is much more transmissive and affects more elderly individuals than youth and more men than women. In response to the rapidly increasing number of publications on the emerging disease, this article attempts to provide a timely and comprehensive review of the swiftly developing research subject. We will cover the basics about the epidemiology, etiology, virology, diagnosis, treatment, prognosis, and prevention of the disease. Although many questions still require answers, we hope that this review helps in the understanding and eradication of the threatening disease.

COVID-19: what has been learned and to be learned about the novel coronavirus disease

The outbreak of Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome (SARS) coronavirus 2 (SARS-CoV-2), has thus far killed over 3,000 people and infected over 80,000 in China and elsewhere in the world, resulting in catastrophe for humans. Similar to its homologous virus, SARS-CoV, which caused SARS in thousands of people in 2003, SARS-CoV-2 might also be transmitted from the bats and causes similar symptoms through a similar mechanism. However, COVID-19 has lower severity and mortality than SARS but is much more transmissive and affects more elderly individuals than youth and more men than women. In response to the rapidly increasing number of publications on the emerging disease, this article attempts to provide a timely and comprehensive review of the swiftly developing research subject. We will cover the basics about the epidemiology, etiology, virology, diagnosis, treatment, prognosis, and prevention of the disease. Although many questions still require answers, we hope that this review helps in the understanding and eradication of the threatening disease.

JAK/STAT Cytokine Signaling at the Crossroad of NK Cell Development and Maturation

Natural Killer (NK) cells are cytotoxic lymphocytes of the innate immune system and play a critical role in anti-viral and anti-tumor responses. NK cells develop in the bone marrow from hematopoietic stem cells (HSCs) that differentiate through common lymphoid progenitors (CLPs) to NK lineage-restricted progenitors (NKPs). The orchestrated action of multiple cytokines is crucial for NK cell development and maturation. Many of these cytokines such as IL-2, IL-7, IL-12, IL-15, IL-21, IL-27, and interferons (IFNs) signal via the Janus Kinase / Signal Transducer and Activator of Transcription (JAK/STAT) pathway. We here review the current knowledge about these cytokines and the downstream signaling involved in the development and maturation of conventional NK cells and their close relatives, innate lymphoid cells type 1 (ILC1). We further discuss the role of suppressor of cytokine signaling (SOCS) proteins in NK cells and highlight their potential for therapeutic application.

AuNP-M2e + sCpG vaccination of juvenile mice generates lifelong protective immunity to influenza A virus infection

Background

Influenza virus infection causes significant morbidity and mortality worldwide. Humans fail to make a universally protective memory response to influenza A because of high mutation rates in the immune-dominant influenza epitopes. We seek the development of a universal influenza A vaccine. The extracellular domain of the M2-ion channel (M2e) is an ideal antigenic target, as it is highly conserved, has a low mutation rate, and is essential for viral entry and replication. Considering the potential of a universal influenza vaccine for lifelong protection, we aimed to examine this potential using a recently published gold nanoparticle M2e vaccine with CpG as an adjuvant (AuNP-M2e + sCpG). Intranasal vaccination induces an M2e-specific memory response, which is protective against lethal infection with H1N1, H3N2, and H5N1 serotypes, in young BALB/c mice. Protection with AuNP-M2e + sCpG has been published up to 8 months after vaccination. However, the highest risk population during most influenza seasons is adults over 65 years old. Additionally, the efficacy of many vaccines decrease after aging and requiring booster vaccinations to remain effective.

Results

To determine if the AuNP-M2e + sCpG vaccine is a viable option as a universal vaccination capable of protection through geriatric age, we tested if the AuNP-M2e + sCpG vaccination loses efficacy after aging mice to geriatric age (over 18 months). Our data shows that mice aged 15 months after vaccination (~ 18-21 months old) retain significant M2e-specific antibody titers in total IgG, IgG1, IgG2a, and IgG2b. These mice are significantly protected from lethal influenza challenge (H1N1, 8.3 PFU). Further, these antibody titers increase upon infection with influenza A and remain elevated for 3 months, suggesting the elderly mice retain effective M2e-specific memory B cells.

Conclusions

Our results demonstrate that protective M2e-specific memory in mice developed at a young age can persist until geriatric age. Additionally, this memory is protective and M2e-specific B cells produced by vaccination with AuNP-M2e + sCpG are maintained and functional. If the results of this study persist in humans, they suggest that a universal influenza A vaccine could be administered early in life and maintain lifelong protection into geriatric age.

Suppressor of cytokine signaling genes in renal transplant receivers: Association with transplant fate

Suppressor of cytokine signaling (SOCS) proteins have acknowledged roles in regulation of immune responses. Moreover, their role in the evolution of allograft rejection is being elucidated. In the current investigation, we measured transcript levels of SOCS1-4 in the peripheral blood of a group of renal transplant recipients including both rejected and non-rejected allografts. Expression analyses showed that relative expression of SOCS2 was significantly higher in transplant-rejected male patients compared to non-rejected group. However, such significant difference was not detected between female subjects. Expression of SOCS2 was significantly higher in T-cell-mediated rejection group compared with non-rejected individuals with creatinine rise (Relative expression difference [95% CrI] =6.74 [0.94, 12.65], P = 0.043). Conversely, SOCS4 expression was significantly lower in T-cell-mediated rejection group compared with non-rejected individuals with creatinine rise (Relative expression difference [95% CrI] = -0.35 [-0.63, -0.1], P = 0.008). Patterns of correlations between expression levels of SOCS genes were different in non-rejected group. The obtained results indicate the role SOCS genes in development of allograft rejection.

Insights into the Evolution of the Suppressors of Cytokine Signaling (SOCS) Gene Family in Vertebrates

The SOCS family are key negative regulators of cytokine and growth factor signaling. Typically, 8-17 SOCS genes are present in vertebrate species with eight known in mammals, classified as type I (SOCS4-7) and type II (CISH and SOCS1-3) SOCS. It was believed that the type II SOCS were expanded through the two rounds of whole genome duplication (1R and 2R WGDs) from a single CISH/SOCS1-3 precursor. Previously, 12 genes were identified in rainbow trout but here we report 15 additional loci are present, and confirm 26 of the genes are expressed, giving rainbow trout the largest SOCS gene repertoire identified to date. The discovery of the additional SOCS genes in trout has led to a novel model of SOCS family evolution, whereby the vertebrate SOCS gene family was derived from CISH/SOCS2, SOCS1/SOCS3, SOCS4/5, SOCS6, and SOCS7 ancestors likely present before the two WGD events. It is also apparent that teleost SOCS2b, SOCS4, and SOCS5b molecules are not true orthologues of mammalian SOCS2, SOCS4, and SOCS5, respectively. The rate of SOCS gene structural changes increased from 2R vertebrates, to 4R rainbow trout, and the genes with structural changes show large differences and low correlation coefficient of expression levels relative to their paralogues, suggesting a role of structural changes in expression and functional diversification. This study has important impacts in the functional prediction and understanding of the SOCS gene family in different vertebrates, and provides a framework for determining how many SOCS genes could be expected in a particular vertebrate species/lineage.

SOCS4 expressed by recombinant HSV protects against cytokine storm in a mouse model

Oncolytic viruses are genetically engineered viruses designed for the treatment of solid tumors, and are often coupled with the antitumor immunity of the host. The challenge of using oncolytic herpes simplex virus (oHSV) as an efficacious oncolytic agent is the potential host tissue damage caused by the production of a range of cytokines following intratumoral oHSV injection. An HSV-suppressor of cytokine signaling 4 (SOCS4) recombinant virus was created to investigate whether it inhibits cytokine storm. Recombinant HSV-SOCS4 and HSV-1(F) were used to infect mice, and levels of several representative cytokines, including monocyte chemoattractant protein-1, interleukin (IL)-1β, tumor necrosis factor-α, IL-6 and interferon γ, in serum and bronchoalveolar lavage fluid (BALF) of infected mice were determined, and immune cells in BALF and spleen were enumerated. Lung damage, virus titers in the lung, body weight and survival rates of infected mice were also determined and compared between the two groups. The cytokine concentration of HSV-SOCS4-infected mice was significantly decreased compared with that of HSV-1(F)-infected mice in BALF and serum, and a smaller number of cluster of differentiation (CD)11b⁺ cells of BALF, and CD8⁺CD62L⁺ T cells and CD4⁺CD62L⁺ T cells of the spleen were also identified in HSV-SOCS4-infected mice. HSV-SOCS4-infected mice exhibited slight lung damage, a decrease in body weight loss and a 100% survival rate. The results of the present study indicated that SOCS4 protein may be a useful regulator to inhibit cytokine overproduction, and that HSV-SOCS4 may provide a possible solution to control cytokine storm and its consequences following induction by oncolytic virus treatment.

Combined use of live-attenuated and inactivated influenza vaccines to enhance heterosubtypic protection

The limited protection of current commerical vaccines necessitates the investigation of novel vaccine strategies for unpredictable outbreaks. To investigate the feasibility of using vaccines derived from Group 1 influenza A virus to induce broadly cross-reactive immune responses against multiple influenza subtypes, we tested a panel of sequential 4-dose immunization regimens in mice. Mice were treated with inactivated (seasonal H1N1, pandemic H1N1 and H5N1) and vaccinia virus-based H5N1 live-attenuated vaccines in different combinations. Mice were then challenged by viruses of either Group 1 (H1N1) or Group 2 (H3N2, H7N7) influenza virus. All studied sequential 4-dose vaccinations could induce some degrees of heterosubtypic protection in mice. Amongst all these regimens, the combined use of inactivated and live-attenuated vaccines could achieve the best heterologous protection. These results highlight the synergistic effect of combining different vaccine platforms to enhance heterosubtypic protection against influenza viruses.

Understanding SOCS protein specificity

The development and activity of our immune system are largely controlled by the action of pleiotropic cytokines and growth factors, small secreted proteins, which bind to receptors on the surface of immune cells to initiate an appropriate physiological response. Cytokine signalling is predominantly executed by intracellular proteins known as the Janus kinases (JAKs) and the signal transducers and activators of transcriptions (STATs). Although the 'nuts and bolts' of cytokine-activated pathways have been well established, the nuanced way in which distinct cellular outcomes are achieved and the precise molecular details of the proteins that regulate these pathways are still being elucidated. This is highlighted by the intricate role of the suppressor of cytokine signalling (SOCS) proteins. The SOCS proteins act as negative feedback inhibitors, dampening specific cytokine signals to prevent excessive cellular responses and returning the cell to a homeostatic state. A great deal of study has demonstrated their ability to inhibit these pathways at the receptor complex, either through direct inhibition of JAK activity or by targeting the receptor complex for proteasomal degradation. Detailed analysis of individual SOCS proteins is slowly revealing the complex and highly controlled manner by which they can achieve specificity for distinct substrates. However, for many of the SOCS, a level of detail is still lacking, including confident identification of the full suite of tyrosine phosphorylated targets of their SH2 domain. This review will highlight the general mechanisms which govern SOCS specificity of action and discuss the similarities and differences between selected SOCS proteins, focusing on CIS, SOCS1 and SOCS3. Because of the functional and sequence similarities within the SOCS family, we will also discuss the evidence for functional redundancy.

SOCS-mediated immunomodulation of natural killer cells

Natural killer (NK) cells are innate immune cells with an intrinsic ability to detect and kill infected and cancerous cells. The success of therapies targeting immune checkpoints on CD8 cells has intensified interest in harnessing the cytolytic effector functions of NK cells for new cancer treatments. NK cell development, survival and effector activity is dependent on exposure to the cytokine interleukin (IL)-15. The suppressor of cytokine (SOCS) proteins (CIS; SOCS1-7) are important negative regulators of cytokine signaling, and both CIS and SOCS2 are reported to have roles in regulating NK cell responses. Their immunomodulatory effects on NK cells suggest that these SOCS proteins are promising targets that can potentially form the basis of novel cancer therapies. Here we discuss the role of NK cells in tumor immunity as well as review the role of the SOCS proteins in regulating IL-15 signaling and NK cell function.

MicroRNA-let-7e regulates the progression and development of allergic rhinitis by targeting suppressor of cytokine signaling 4 and activating Janus kinase 1/signal transducer and activator of transcription 3 pathway

The present study aimed to explore the microRNA-let-7e (miR-let-7e) expression in allergic rhinitis (AR), and to investigate the underlying molecular mechanisms. miR-let-7e expression in the nasal mucosa of mice and patients with AR were detected. The expression levels of three inflammatory factors, including histamine, immunoglobulin E and tumor necrosis factor-α (TNF-α), in the blood of AR mice and in interleukin (IL)-13-stimulated nasal epithelial cells (NECs) were also measured. Furthermore, the target gene of miR-let-7e was predicted and validated using a luciferase reporter assay. The expression levels of Janus kinase 1 (JAK1) and signal transducer and activator of transcription 3 (STAT3) were detected. The results demonstrated that miR-let-7e was downregulated in patients and mice with AR compared with the controls. In addition, the expression levels of inflammatory factors were higher in the blood of mice with AR compared with the control group, while miR-let-7e overexpression inhibited these levels in AR mice and IL-13-stimulated NECs. Furthermore, suppressor of cytokine signaling 4 (SOCS4) was revealed as a potential target gene of miR-let-7e and was negatively regulated by miR-let-7e. Overexpression of SOCS4 abrogated the anti-inflammatory activity of miR-let-7e overexpression. Finally, miR-let-7e overexpression activated the JAK1/STAT3 signaling pathway. In conclusion, miR-let-7e may serve an important role in the progression and development of AR, while overexpression of miR-let-7e had an anti-inflammatory effect by targeting SOCS4, which may be achieved by activation of the JAK1/STAT3 signaling pathway.

MicroRNA-302a suppresses influenza A virus-stimulated interferon regulatory factor-5 expression and cytokine storm induction

During influenza A virus (IAV) infection, cytokine storms play a vital and critical role in clinical outcomes. We have previously reported that microRNA (miR)-302c regulates IAV-induced IFN expression by targeting the 3'-UTR of nuclear factor κB (NF-κB)-inducing kinase. In the current study, we found that miR-302a, another member of the miR-302 cluster, controls the IAV-induced cytokine storm. According to results from cell-based and knockout mouse models, IAV induces a cytokine storm via interferon regulatory factor-5 (IRF-5). We also found that IAV infection up-regulates IRF-5 expression and that IRF-5 in turn promotes IAV replication. Furthermore, we observed that IRF-5 is a direct target of miR-302a, which down-regulated IRF-5 expression by binding its 3'-UTR. Moreover, IAV increased IRF-5 expression by down-regulating miR-302a expression. Interestingly, miR-302a inhibited IAV replication. In IAV-infected patients, miR-302a expression was down-regulated, whereas IRF-5 expression was up-regulated. Taken together, our work uncovers and defines a signaling pathway implicated in an IAV-induced cytokine storm.

In vitro significance of SOCS-3 and SOCS-4 and potential mechanistic links to wound healing

Wound healing and the management of chronic wounds represent a significant burden on the NHS. Members of the suppressor of cytokine signalling (SOCS) family have been implicated in the regulation of a range of cellular processes. The current study aims to explore the importance of SOCS-3 and SOCS-4 in regulating cellular traits associated with wound healing. SOCS-3 over-expression and SOCS-4 knockdown mutant lines were generated and verified using q-PCR and western blotting in human keratinocytes (HaCaT) and endothelial cells (HECV). Over-expression of SOCS-3 resulted in a significantly reduced proliferative rate in HaCaT keratinocytes and also enhanced the tubule formation capacity of HECV cells. SOCS-4 knockdown significantly reduced HaCaT migration and HECV cell tubule formation. Suppression of SOCS-4 influenced the responsiveness of HaCaT and HECV cells to EGF and TGFβ and resulted in a dysregulation of phospho-protein expression in HaCaT cells. SOCS-3 and SOCS-4 appear to play regulatory roles in a number of keratinocyte and endothelial cellular traits associated with the wound healing process and may also be able to regulate the responsiveness of these cells to EGF and TGFβ. This implies a potential regulatory role in the wound healing process and, thus highlights their potential as novel therapies.

Suppressors of cytokine signaling in tuberculosis

Tuberculosis (TB), a global disease mainly infected by Mycobacterium tuberculosis, remains leading public health problem worldwide. Suppressors of cytokine signaling (SOCSs) play important roles in the protection against microbial infection. However, the relationship between members of the SOCS family and tuberculosis infection remains unclear. Using peripheral blood mononuclear cells, we investigated the mRNA expression profiles of SOCS subfamilies among active TB, latent tuberculosis infection (LTBI), and healthy individuals. Our results showed that active tuberculosis subjects had higher levels of SOCS-3 mRNA, lower expressions of SOCS-2, -4, -5, -6, -7, and cytokine-inducible SH2-containing protein-1 (CIS-1) mRNAs, but not SOCS-1 mRNA than healthy and LTBI subjects. In men, LTBI patients had lower SOCS-3 than healthy subjects, and active TB patients had lower levels of SOCS-4, -5, and CIS-1 mRNAs but higher levels of SOCS-3 mRNA than healthy subjects. In women, LTBI patients had lower SOCS-3 mRNA level than healthy subjects, and active TB patients had lower CIS-1 mRNA level than healthy subjects. In non-aged adults (< 65 years old), TB patients had higher SOCS-3 mRNA and lower levels of SOCS-2, -4, -5, -6, -7, and CIS-1 mRNAs; whereas, aged TB patients (≥ 65 years old) had lower levels of SOCS-5 and CIS-1 mRNAs. These data suggest that particular SOCS members and their correlative relationships allow discrimination of active TB from healthy and LTBI subjects.

Suppressor of cytokine signaling (SOCS)5 ameliorates influenza infection via inhibition of EGFR signaling

Influenza virus infections have a significant impact on global human health. Individuals with suppressed immunity, or suffering from chronic inflammatory conditions such as COPD, are particularly susceptible to influenza. Here we show that suppressor of cytokine signaling (SOCS) five has a pivotal role in restricting influenza A virus in the airway epithelium, through the regulation of epidermal growth factor receptor (EGFR). Socs5-deficient mice exhibit heightened disease severity, with increased viral titres and weight loss. Socs5 levels were differentially regulated in response to distinct influenza viruses (H1N1, H3N2, H5N1 and H11N9) and were reduced in primary epithelial cells from COPD patients, again correlating with increased susceptibility to influenza. Importantly, restoration of SOCS5 levels restricted influenza virus infection, suggesting that manipulating SOCS5 expression and/or SOCS5 targets might be a novel therapeutic approach to influenza.

Kinase inhibition, competitive binding and proteasomal degradation: resolving the molecular function of the suppressor of cytokine signaling (SOCS) proteins

The suppressor of cytokine signaling (SOCS) family of proteins are key negative regulators of cytokine and growth factor signaling. They act at the receptor complex to modulate the intracellular signaling cascade, preventing excessive signaling and restoring homeostasis. This regulation is critical to the normal cessation of signaling, highlighted by the complex inflammatory phenotypes exhibited by mice deficient in SOCS1 or SOCS3. These two SOCS proteins remain the best characterized of the eight family members (CIS, SOCS1-7), and in particular, we now possess a sound understanding of the mechanism of action for SOCS3. Here, we review the mechanistic role of the SOCS proteins and identify examples where clear, definitive data have been generated and discuss areas where the information is less clear. From this functional viewpoint, we discuss how the SOCS proteins achieve exquisite and specific regulation of cytokine signaling and highlight outstanding questions regarding the function of the less well-studied SOCS family members.

Human mesenchymal stromal cells reduce influenza A H5N1-associated acute lung injury in vitro and in vivo

Influenza can cause acute lung injury. Because immune responses often play a role, antivirals may not ensure a successful outcome. To identify pathogenic mechanisms and potential adjunctive therapeutic options, we compared the extent to which avian influenza A/H5N1 virus and seasonal influenza A/H1N1 virus impair alveolar fluid clearance and protein permeability in an in vitro model of acute lung injury, defined the role of virus-induced soluble mediators in these injury effects, and demonstrated that the effects are prevented or reduced by bone marrow-derived multipotent mesenchymal stromal cells. We verified the in vivo relevance of these findings in mice experimentally infected with influenza A/H5N1. We found that, in vitro, the alveolar epithelium's protein permeability and fluid clearance were dysregulated by soluble immune mediators released upon infection with avian (A/Hong Kong/483/97, H5N1) but not seasonal (A/Hong Kong/54/98, H1N1) influenza virus. The reduced alveolar fluid transport associated with down-regulation of sodium and chloride transporters was prevented or reduced by coculture with mesenchymal stromal cells. In vivo, treatment of aged H5N1-infected mice with mesenchymal stromal cells increased their likelihood of survival. We conclude that mesenchymal stromal cells significantly reduce the impairment of alveolar fluid clearance induced by A/H5N1 infection in vitro and prevent or reduce A/H5N1-associated acute lung injury in vivo. This potential adjunctive therapy for severe influenza-induced lung disease warrants rapid clinical investigation.

Avian Influenza Viruses, Inflammation, and CD8(+) T Cell Immunity

Avian influenza viruses (AIVs) circulate naturally in wild aquatic birds, infect domestic poultry, and are capable of causing sporadic bird-to-human transmissions. AIVs capable of infecting humans include a highly pathogenic AIV H5N1, first detected in humans in 1997, and a low pathogenic AIV H7N9, reported in humans in 2013. Both H5N1 and H7N9 cause severe influenza disease in humans, manifested by acute respiratory distress syndrome, multi-organ failure, and high mortality rates of 60% and 35%, respectively. Ongoing circulation of H5N1 and H7N9 viruses in wild birds and poultry, and their ability to infect humans emphasizes their epidemic and pandemic potential and poses a public health threat. It is, thus, imperative to understand the host immune responses to the AIVs so we can control severe influenza disease caused by H5N1 or H7N9 and rationally design new immunotherapies and vaccines. This review summarizes our current knowledge on AIV epidemiology, disease symptoms, inflammatory processes underlying the AIV infection in humans, and recent studies on universal pre-existing CD8(+) T cell immunity to AIVs. Immune responses driving the host recovery from AIV infection in patients hospitalized with severe influenza disease are also discussed.

The cytokine storm of severe influenza and development of immunomodulatory therapy

Severe influenza remains unusual in its virulence for humans. Complications or ultimately death arising from these infections are often associated with hyperinduction of proinflammatory cytokine production, which is also known as 'cytokine storm'. For this disease, it has been proposed that immunomodulatory therapy may improve the outcome, with or without the combination of antiviral agents. Here, we review the current literature on how various effectors of the immune system initiate the cytokine storm and exacerbate pathological damage in hosts. We also review some of the current immunomodulatory strategies for the treatment of cytokine storms in severe influenza, including corticosteroids, peroxisome proliferator-activated receptor agonists, sphingosine-1-phosphate receptor 1 agonists, cyclooxygenase-2 inhibitors, antioxidants, anti-tumour-necrosis factor therapy, intravenous immunoglobulin therapy, statins, arbidol, herbs, and other potential therapeutic strategies.

Galectins regulate the inflammatory response in airway epithelial cells exposed to microbial neuraminidase by modulating the expression of SOCS1 and RIG1

Influenza patients frequently display increased susceptibility to Streptococcus pneumoniae co-infection and sepsis, the prevalent cause of mortality during influenza pandemics. However, the detailed mechanisms by which an influenza infection predisposes patients to suffer pneumococcal pneumonia are not fully understood. A murine model for influenza infection closely reflects the observations in human patients, since if the animals that have recovered from influenza A virus (IAV) sublethal infection are challenged with S. pneumoniae, they undergo a usually fatal uncontrolled cytokine response. We have previously demonstrated both in vitro and in vivo that the expression and secretion of galectin-1 (Gal1) and galectin-3 (Gal3) are modulated during IAV infection, and that the viral neuraminidase unmasks galactosyl moieties in the airway epithelia. In this study we demonstrate in vitro that the binding of secreted Gal1 and Gal3 to the epithelial cell surface modulates the expression of SOCS1 and RIG1, and activation of ERK, AKT or JAK/STAT1 signaling pathways, leading to a disregulated expression and release of pro-inflammatory cytokines. Our results suggest that the activity of the viral and pneumococcal neuraminidases on the surface of the airway epithelial cells function as a "danger signal" that leads to rapid upregulation of SOCS1 expression to prevent an uncontrolled inflammatory response. The binding of extracellular Gal1 or Gal3 to the galactosyl moieties unmasked on the surface of airway epithelial cells can either "fine-tune" or severely disregulate this process, respectively, the latter potentially leading to hypercytokinemia.

Regulation of Macrophage, Dendritic Cell, and Microglial Phenotype and Function by the SOCS Proteins

Macrophages are innate immune cells of dynamic phenotype that rapidly respond to external stimuli in the microenvironment by altering their phenotype to respond to and to direct the immune response. The ability to dynamically change phenotype must be carefully regulated to prevent uncontrolled inflammatory responses and subsequently to promote resolution of inflammation. The suppressor of cytokine signaling (SOCS) proteins play a key role in regulating macrophage phenotype. In this review, we summarize research to date from mouse and human studies on the role of the SOCS proteins in determining the phenotype and function of macrophages. We will also touch on the influence of the SOCS on dendritic cell (DC) and microglial phenotype and function. The molecular mechanisms of SOCS function in macrophages and DCs are discussed, along with how dysregulation of SOCS expression or function can lead to alterations in macrophage/DC/microglial phenotype and function and to disease. Regulation of SOCS expression by microRNA is discussed. Novel therapies and unanswered questions with regard to SOCS regulation of monocyte-macrophage phenotype and function are highlighted.

A missense mutation underlies defective SOCS4 function in a family with autoimmunity

OBJECTIVE

The aim of this study was to determine the genetic and immunological defects underlying familial manifestations of an autoimmune disorder.

METHODS

Whole-exome sequencing was performed on the index patient with various manifestations of autoimmunity, including hypothyroidism, vitiligo and alopecia. Peripheral blood mononuclear cells and DNA of family members were used for functional and genetic testing of the candidate variants obtained by Sanger sequencing.

RESULTS

Exome sequencing identified 233 rare, coding and nonsynonymous variants in the index patient; five were highly conserved and affect genes that have a possible role in autoimmunity. Only a heterozygous missense mutation in the suppressor of cytokine signalling 4 gene (SOCS4) cosegregated with the autoimmune disorder in the family. SOCS4 is a known inhibitor of epidermal growth factor (EGF) receptor signalling, and functional studies demonstrated specific upregulation of EGF-dependent immune stimulation in affected family members.

CONCLUSION

We present a family with an autoimmune disorder, probably resulting from dysregulated immune responses due to mutations in SOCS4.

The Flavonoid Isoliquiritigenin Reduces Lung Inflammation and Mouse Morbidity during Influenza Virus Infection

The host response to influenza virus infection is characterized by an acute lung inflammatory response in which intense inflammatory cell recruitment, hypercytokinemia, and a high level of oxidative stress are present. The sum of these events contributes to the virus-induced lung damage that leads to high a level of morbidity and mortality in susceptible infected patients. In this context, we identified compounds that can simultaneously reduce the excessive inflammatory response and the viral replication as a strategy to treat influenza virus infection. We investigated the anti-inflammatory and antiviral potential activities of isoliquiritigenin (ILG). Interestingly, we demonstrated that ILG is a potent inhibitor of influenza virus replication in human bronchial epithelial cells (50% effective concentration [EC50] = 24.7 μM). In addition, our results showed that this molecule inhibits the expression of inflammatory cytokines induced after the infection of cells with influenza virus. We demonstrated that the anti-inflammatory activity of ILG in the context of influenza virus infection is dependent on the activation of the peroxisome proliferator-activated receptor gamma pathway. Interestingly, ILG phosphate (ILG-p)-treated mice displayed decreased lung inflammation as depicted by reduced cytokine gene expression and inflammatory cell recruitment. We also demonstrated that influenza virus-specific CD8(+) effector T cell recruitment was reduced up to 60% in the lungs of mice treated with ILG-p (10 mg/kg) compared to that in saline-treated mice. Finally, we showed that administration of ILG-p reduced lung viral titers and morbidity of mice infected with the PR8/H1N1 virus.