Role of CD1d and iNKT cells in regulating intestinal inflammation

Invariant natural killer T (iNKT) cells, a subset of unconventional T cells that recognize glycolipid antigens in a CD1d-dependent manner, are crucial in regulating diverse immune responses such as autoimmunity. By engaging with CD1d-expressing non-immune cells (such as intestinal epithelial cells and enterochromaffin cells) and immune cells (such as type 3 innate lymphoid cells, B cells, monocytes and macrophages), iNKT cells contribute to the maintenance of immune homeostasis in the intestine. In this review, we discuss the impact of iNKT cells and CD1d in the regulation of intestinal inflammation, examining both cellular and molecular factors with the potential to influence the functions of iNKT cells in inflammatory bowel diseases such as Crohn's disease and ulcerative colitis.

The protective role of 5-hydroxy-1,4-naphthoquinone against the harmful effects of 50 Hz electric field in rat lung tissue

There is strong scientific evidence that the electric field is harmful to life. Exposure to an electric field (EF) can cause lung toxicity and respiratory disorders. In addition, the electric field has been shown to cause tissue damage through inflammation and apoptosis. Juglone (JUG) is one of the powerful antioxidants with anti-apoptotic and anti-inflammatory, various pharmacological properties in the biological system. In this study, we evaluated the efficacy of JUG against the potential adverse effects of electric field on the lung. Twenty-four Wistar albino rats were randomly divided into three groups; control group (Cont), EF group, and EF exposure+JUG-treated group (EJUG). After routine histological procedures, sections stained with hematoxylin-eosin (H&E) showed significant changes in lung tissues in the EF group compared to the Cont group. Significant protective effects were observed in the building volumes and histopathology in the EJUG group. Our immunohistochemical and gene expression results increased the expression of caspase-3 and tumor necrosis factor alpha (TNF-α) in the EF group (p < 0.05). Juglon increased cytokine signal suppressor (SOCS) expression (p < 0.001). These findings were consistent with the antioxidant effect of JUG treatment. We reasoned that exposure to EF damaged rat lung tissues and administration of JUG alleviated the complications caused by 50 Hz EF.

Maternal stevioside supplementation improves intestinal immune function of chicken offspring potentially via modulating gut microbiota and down-regulating the promoter methylation level of suppressor of cytokine signaling 1 (SOCS1)

The intestinal immune function of chickens is limited during the early growing stage. Maternal nutritional intervention has been suggested to affect the innate immunity of offspring. The present study aimed to investigate the effects of maternal stevioside supplementation on the intestinal immune function of chicken offspring. A total of 120 Jinmao yellow-feathered breeder hens were fed a basal diet or a diet supplemented with 250 mg/kg stevioside for 5 weeks. During the last week, 200 breeding eggs from each group were collected for incubation. After hatching, 80 male offspring (40 chickens from each group) were randomly selected and fed the same basal diet for 28 d. In addition, 90 well-shaped fertile eggs of non-treated breeder hens were incubated for the in ovo injection experiment. Steviol dissolved in 20% glycerol was injected at 7 d of incubation. The results showed that maternal stevioside supplementation could improve embryonic development, jejunal integrity and proliferation in the jejunal crypt (P < 0.05). Maternal stevioside supplementation could also increase the innate transcription levels of cytokines and endotoxin tolerance-related factors in the jejunum of chicken offspring (P < 0.05). At 28 d of age, the offspring following maternal stevioside supplementation exhibited higher jejunal secretory immunoglobulin A and serum interferons levels (P < 0.05). A higher abundance of Lactobacillales induced by maternal stevioside supplementation was positively correlated with intestinal immune-related factors (P < 0.05). The in ovo injection with steviol did not alter either embryonic development or intestinal immune function of hatching chickens (P > 0.05). Furthermore, maternal stevioside supplementation could induce hypo-methylation on the promoter region of suppressor of cytokine signaling 1 (SOCS1). In conclusion, maternal stevioside supplementation could improve the intestinal immune function of chicken offspring potentially via modulating the gut microbiota and down-regulating the promoter methylation level of SOCS1.

A single-cell analysis of thymopoiesis and thymic iNKT cell development in pigs

Many aspects of the porcine immune system remain poorly characterized, which poses a barrier to improving swine health and utilizing pigs as preclinical models. Here, we employ single-cell RNA sequencing (scRNA-seq) to create a cell atlas of the early-adolescent pig thymus. Our data show conserved features as well as species-specific differences in cell states and cell types compared with human thymocytes. We also describe several unconventional T cell types with gene expression profiles associated with innate effector functions. This includes a cell census of more than 11,000 differentiating invariant natural killer T (iNKT) cells, which reveals that the functional diversity of pig iNKT cells differs substantially from the iNKT0/1/2/17 subset differentiation paradigm established in mice. Our data characterize key differentiation events in porcine thymopoiesis and iNKT cell maturation and provide important insights into pig T cell development.

hsa-MiR-19a-3p and hsa-MiR-19b-3p Are Associated with Spinal Cord Injury-Induced Neuropathic Pain: Findings from a Genome-Wide MicroRNA Expression Profiling Screen

Neuropathic pain in spinal cord injury (SCI) is associated with inflammation in both the peripheral and central nervous system (CNS), which may contribute to the initiation and maintenance of persistent pain. An understanding of factors contributing to neuroinflammation may lead to new therapeutic targets for neuropathic pain. Moreover, novel circulating biomarkers of neuropathic pain may facilitate earlier and more effective treatment. MicroRNAs (miRNAs) are short, non-coding single-stranded RNA that have emerged as important biomarkers and molecular mediators in physiological and pathological conditions. Using a genome-wide miRNA screening approach, we studied differential miRNA expression in plasma from 68 healthy, community-dwelling adults with and without SCI enrolled in ongoing clinical studies. We detected 2367 distinct miRNAs. Of these, 383 miRNAs were differentially expressed in acute SCI or chronic SCI versus no SCI and 71 were differentially expressed in chronic neuropathic pain versus no neuropathic pain. We selected homo sapiens (hsa)-miR-19a-3p and hsa-miR-19b-3p for additional analysis based on p-value, fold change, and their known role as regulators of neuropathic pain and neuroinflammation. Both hsa-miR-19a-3p and hsa-miR-19b-3p levels were significantly higher in those with chronic SCI and severe neuropathic pain versus those with chronic SCI and no neuropathic pain. In confirmatory studies, both hsa-miR-19a-3p and hsa-miR-19b-3p have moderate to strong discriminative ability to distinguish between those with and without pain. After adjusting for opioid use, hsa-miR-19b-3p levels were positively associated with pain interference with mood. Because hsa-miR-19 levels have been shown to change in response to exercise, folic acid, and resveratrol, these studies suggest that miRNAs are potential targets of therapeutic interventions.

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.

Natural Killer T Cells in Various Mouse Models of Hepatitis

Natural killer T (NKT) cells are a key component of innate immunity. Importantly, a growing body of evidence indicates that NKT cells play an integral role in various acute and chronic liver injuries. NKT cells participate in the progression of an injury through the secretion of cytokines, which promote neutrophil infiltration and enhance Fas ligand (FasL) and granzyme-mediated NKT cytotoxic activity. Therefore, examining the role of NKT cells in hepatic disease is critical for a comprehensive understanding of disease pathogenesis and may provide insight into novel approaches for treatment. For more than a century, mouse models that imitate the physiopathological conditions of human disease have served as a critical tool in biological and medical basic research, including studies of liver disease. Here, we review the role of NKT cells in various mouse models of hepatitis.

Constitutively elevated levels of SOCS1 suppress innate responses in DF-1 immortalised chicken fibroblast cells

The spontaneously immortalised DF-1 cell line is rapidly replacing its progenitor primary chicken embryo fibroblasts (CEFs) for studies on avian viruses such as avian influenza but no comprehensive study has as yet been reported comparing their innate immunity phenotypes. We conducted microarray analyses of DF-1 and CEFs, under both normal and stimulated conditions using chicken interferon-α (chIFN-α) and the attenuated infectious bursal disease virus vaccine strain PBG98. We found that DF-1 have an attenuated innate response compared to CEFs. Basal expression levels of Suppressor of Cytokine Signalling 1 (chSOCS1), a negative regulator of cytokine signalling in mammals, are 16-fold higher in DF-1 than in CEFs. The chSOCS1 “SOCS box” domain (which in mammals, interacts with an E3 ubiquitin ligase complex) is not essential for the inhibition of cytokine-induced JAK/STAT signalling activation in DF-1. Overexpression of SOCS1 in chIFN-α-stimulated DF-1 led to a relative decrease in expression of interferon-stimulated genes (ISGs; MX1 and IFIT5) and increased viral yield in response to PBG98 infection. Conversely, knockdown of SOCS1 enhanced induction of ISGs and reduced viral yield in chIFN-α-stimulated DF-1. Consequently, SOCS1 reduces induction of the IFN signalling pathway in chicken cells and can potentiate virus replication.

[Polymorphic variants of the immune response genes as risk factors for primary progressive multiple sclerosis]

AIM

To analyze the involvement of immune response genes in the pathogenesis of primary progressive multiple sclerosis (PPMS).

MATERIAL AND METHODS

This multicenter study included 111 patients with PPMS from the Russian ethnic group. The association of PPMS with genes of immune system was analyzed by the study of polymorphic variants of genes of cytokines and genes of antigen-presenting cells.

RESULTS AND CONCLUSION

The genotypes of IL-4 (rs2243250)*C/C and CLEC16A (rs6498169)*G/G were associated with PPMS in Russians. The association between the HLA-DRB1*15 and PPMS found out in other populations was confirmed in Russians.

Sophocarpine Protects Mice from ConA-Induced Hepatitis via Inhibition of the IFN-Gamma/STAT1 Pathway

Sophocarpine is the major pharmacologically active compound of the traditional Chinese herbal medicine Radix Sophorae Subprostratae which has been used in treating hepatitis for years in China. It has been demonstrated that Sophocarpine exerts an activity in immune modulation and significantly decreases the production of inflammatory cytokines. However, the protective effects of Sophocarpine in T cell-dependent immune hepatitis remained unknown. The aim of this study was to determine the protective effects and pharmacological mechanisms of Sophocarpine on Concanavalin A (ConA)-induced hepatitis, an experimental model of T cell-mediated liver injury. BALB/C mice were pretreated with Sophocarpine or Bicyclol for five consecutive days. Thirty minutes after the final administration, the mice were injected with 15 mg⋅kg^-1 of ConA intravenously. The results indicated that pretreatment with Sophocarpine significantly ameliorated liver inflammation and injury as evidenced by both biochemical and histopathological observations. Moreover, in Sophocarpine-pretreated mice, liver messenger RNA expression levels of chemokines and adhesion molecules, such as macrophage inflammatory protein-1α, CXC chemokine ligand 10, and Intercellular adhesion molecule-1, were markedly reduced. Further studies revealed that Sophocarpine significantly downregulated the expression of T-bet via inhibition of signal transducers and activators of transcription1 (STAT1) activation and overexpression of suppressor of cytokine signaling1, inhibiting the activation of Th1 cells and the expression of Interferon-γ (IFN-γ). Altogether, these results suggest new opportunities to use Sophocarpine in the treatment of T cell-mediated liver disease. In summary, Sophocarpine could attenuate ConA-induced liver injury, and the protective effect of Sophocarpine was associated with its inhibition effect of pro-inflammatory cytokines, chemokines, and the IFN-γ/STAT1 signaling pathway.

Decreased Expression of Vitamin D Receptor Affects an Immune Response in Primary Biliary Cholangitis via the VDR-miRNA155-SOCS1 Pathway

Primary biliary cholangitis (PBC) is an immune-mediated cholestatic disease. Vitamin D receptor (VDR)-dependent signaling constrains an inflammatory response by targeting the miRNA155-SOCS1 (suppressor of cytokine signaling 1) axis. The VDR-miRNA155-SOCS1 pathway was investigated in the context of the autoimmune response associated with PBC. Human liver tissues from non-cirrhotic PBC (n = 22), cirrhotic PBC (n = 22), cirrhotic primary sclerosing cholangitis (PSC, n = 13), controls (n = 23), and peripheral blood mononuclear cells (PBMC) obtained from PBC (n = 16) and PSC (n = 10) patients and healthy subjects (n = 11) were used for molecular analyses. VDR mRNA and protein expressions were substantially reduced in PBC livers (51% and 59%, respectively). Correspondingly, the decrease of SOCS1 protein expression in PBC livers, after normalization to a marker of lymphocytes and forkhead family transcriptional regulator box P3 (FOXP3, marker of Treg), was observed, and this phenomenon was accompanied by enhanced miRNA155 expression. In PSC livers, protein expressions of VDR and SOCS1 were comparable to the controls. However, in PBM cells, protein expressions of VDR and SOCS1 were considerably decreased in both PBC and PSC. We demonstrated that VDR/miRNA155-modulated SOCS1 expression is decreased in PBC which may lead to insufficient negative regulation of cytokine signaling. These findings suggest that the decreased VDR signaling in PBC could be of importance in the pathogenesis of PBC.

Type II NKT cells: a distinct CD1d-restricted immune regulatory NKT cell subset

Type II natural killer T cells (NKT) are a subset of the innate-like CD1d-restricted lymphocytes that are reactive to lipid antigens. Unlike the type I NKT cells, which express a semi-invariant TCR, type II NKT cells express a broader TCR repertoire. Additionally, other features, such as their predominance over type I cells in humans versus mice, the nature of their ligands, CD1d/lipid/TCR binding, and modulation of immune responses, distinguish type II NKT cells from type I NKT cells. Interestingly, it is the self-lipid-reactivity of type II NKT cells that has helped define their physiological role in health and in disease. The discovery of sulfatide as one of the major antigens for CD1d-restricted type II NKT cells in mice has been instrumental in the characterization of these cells, including the TCR repertoire, the crystal structure of the CD1d/lipid/TCR complex, and their function. Subsequently, several other glycolipids and phospholipids from both endogenous and microbial sources have been shown to activate type II NKT cells. The activation of a specific subset of type II NKT cells following administration with sulfatide or lysophosphatidylcholine (LPC) leads to engagement of a dominant immunoregulatory pathway associated with the inactivation of type I NKT cells, conventional dendritic cells, and inhibition of the proinflammatory Th1/Th17 cells. Thus, type II NKT cells have been shown to be immunosuppressive in autoimmune diseases, inflammatory liver diseases, and in cancer. Knowing their relatively higher prevalence in human than type I NKT cells, understanding their biology is imperative for health and disease.

Inhibition of MicroRNA-221 Alleviates Neuropathic Pain Through Targeting Suppressor of Cytokine Signaling 1

Neuropathic pain results in considerable trouble to people's physical and mental health. The pathophysiological mechanisms underlying its occurrence and development remain unclear. A large number of experiments show that microRNAs (miRNAs) play a major role in the pathogenesis of neuropathic pain and neuroinflammation resulting from nerve injury. Among various miRNAs, microRNA-221 (miR-221) overexpression has been reported in a chronic constrictive injury (CCI)-induced rat model of neuropathic pain. However, the role of miR-221 in the regulation of neuropathic pain is unknown. In this study, we investigated the potential role and underlying mechanism of miR-221 in regulating neuropathic pain. Our findings show that miR-221 is overexpressed in the spinal cord and the isolated microglia of CCI rats. Intrathecal injection of a miR-221 inhibitor attenuated CCI-induced mechanical allodynia and thermal hyperalgesia, and reduced proinflammatory cytokine expression, including tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 in CCI rats. Using a dual-luciferase reporter assay, we show that suppressor of cytokine signaling 1 (SOCS1), an important regulator of inflammation, is a direct target of miR-221. Treatment with the miR-221 inhibitor significantly inhibited the expression of SOCS1. Furthermore, the miR-221 inhibitor markedly suppressed the activation of nuclear factor-kappa B (NF-κB) and the p38 mitogen-activated protein kinase (p38 MAPK) signaling pathway. Knockdown of SOCS1 in CCI rats abrogated the inhibitory effect of the miR-221 inhibitor on CCI-induced neuropathic pain and the NF-κB and p38 MAPK signaling pathways. Together, these results suggest that inhibition of miR-221 alleviates neuropathic pain and neuroinflammation through increasing SOCS1 and by inhibiting the NF-κB and p38 MAPK signaling pathways, indicating that miR-221 may be a promising molecular target for the treatment of neuropathic pain.

Suppressor of cytokine signalling (SOCS) proteins as guardians of inflammatory responses critical for regulating insulin sensitivity

Overactivation of immune pathways in obesity is an important cause of insulin resistance and thus new approaches aimed to limit inflammation or its consequences may be effective for treating Type 2 diabetes. The SOCS (suppressors of cytokine signalling) are a family of proteins that play an essential role in mediating inflammatory responses in both immune cells and metabolic organs such as the liver, adipose tissue and skeletal muscle. In the present review we discuss the role of SOCS1 and SOCS3 in controlling immune cells such as macrophages and T-cells and the impact this can have on systemic inflammation and insulin resistance. We also dissect the mechanisms by which SOCS (1-7) regulate insulin signalling in different tissues including their impact on the insulin receptor and insulin receptor substrates. Lastly, we discuss the important findings from SOCS whole-body and tissue-specific null mice, which implicate an important role for these proteins in controlling insulin action and glucose homoeostasis in obesity.

Aryl hydrocarbon receptor plays protective roles in ConA-induced hepatic injury by both suppressing IFN-γ expression and inducing IL-22

The aryl hydrocarbon receptor (AhR), a ligand-activated nuclear transcription factor, is known to mediate the toxic and carcinogenic effects of various environmental pollutants, while AhR has been shown to protect animals from various types of tissue injury. ConA-induced hepatitis is known as a mouse model of acute liver injury. Here, we found a protective role of AhR in ConA-induced hepatitis. AhR is induced in the liver during ConA-induced hepatitis, and Ahr (-/-) mice were highly sensitive to this model. Bone marrow chimera experiments indicate that Ahr (-/-) hematopoietic cells are responsible for hypersensitivity to ConA-induced hepatitis. We found that IFN-γ from invariant NKT cells was up-regulated and IL-22 from innate lymphoid cells (ILCs) was abolished in Ahr (-/-) mice. In addition, IL-22 production was still observed in Rag2 (-/-) mice but it was severely reduced in Ahr (-/-) Rag2 (-/-) mice. ConA-induced IL-22 production was also dependent on retinoic acid-related orphan receptor γt. These results show that AhR has crucial protective roles in ConA-induced liver injury via promoting IL-22 production from ILCs and suppressing IFN-γ expression from NKT cells.

The preventive role of type 2 NKT cells in the development of type 1 diabetes

In the last two decades, natural killer T (NKT) cells have emerged as an important factor in preventing type 1 diabetes (T1D) when investigated in the experimental non-obese diabetic (NOD) mouse model. So far, investigations have largely focused on type 1 NKT cells with invariant T-cell receptors, whereas the role of type 2 NKT cells with diverse T-cell receptors is less well understood. However, there have been several findings which indicate that in fact type 2 NKT cells may regulate the progression of type 1 diabetes in NOD mice, including a fraction of these cells which recognize β-cell-enriched sulfatide. Therefore, the focus for this review is to present the current evidence of the effect of type 2 NKT cells on the development of T1D. In general, there is still uncertainty surrounding the mechanism of activation and function of NKT cells. Here, we present two models of the effector mechanisms, respectively, Th1/Th2 polarization and the induction of tolerogenic dendritic cells (DC). In conclusion, this review points to the importance of immunoregulation by type 2 NKT cells in preventing the development of T1D and highlights the induction of tolerogenic DC as a likely mechanism. The possible therapeutic role of type 1 and type 2 NKT cells are evaluated and future experiments concerning type 2 NKT cells and T1D are proposed.

SOCS, Inflammation, and Autoimmunity

Cytokines play essential roles in innate and adaptive immunity. However, excess cytokines or dysregulation of cytokine signaling will cause a variety of diseases, including allergies, autoimmune diseases, inflammation, and cancer. Most cytokines utilize the so-called Janus kinase–signal transducers and activators of transcription pathway. This pathway is negatively regulated by various mechanisms including suppressors of cytokine signaling (SOCS) proteins. SOCS proteins bind to JAK or cytokine receptors, thereby suppressing further signaling events. Especially, suppressor of cytokine signaling-1 (SOCS1) and SOCS3 are strong inhibitors of JAKs, because these two contain kinase inhibitory region at the N-terminus. Studies using conditional knockout mice have shown that SOCS proteins are key physiological as well as pathological regulators of immune homeostasis. Recent studies have also demonstrated that SOCS1 and SOCS3 are important regulators of helper T cell differentiation and functions. This review focuses on the roles of SOCS1 and SOCS3 in T cell mediated inflammatory diseases.

The split personality of NKT cells in malignancy, autoimmune and allergic disorders

NKT cells are a heterogeneous subset of specialized, self-reactive T cells, with innate and adaptive immune properties, which allow them to bridge innate and adaptive immunity and profoundly influence autoimmune and malignant disease outcomes. NKT cells mediate these activities through their ability to rapidly express pro- and anti-inflammatory cytokines that influence the type and magnitude of the immune response. Not only do NKT cells regulate the functions of other cell types, but experimental evidence has found NKT cell subsets can modulate the functions of other NKT subsets. Depending on underlying mechanisms, NKT cells can inhibit or exacerbate autoimmunity and malignancy, making them potential targets for disease intervention. NKT cells can respond to foreign and endogenous antigenic glycolipid signals that are expressed during pathogenic invasion or ongoing inflammation, respectively, allowing them to rapidly react to and influence a broad array of diseases. In this article we review the unique development and activation pathways of NKT cells and focus on how these attributes augment or exacerbate autoimmune disorders and malignancy. We also examine the growing evidence that NKT cells are involved in liver inflammatory conditions that can contribute to the development of malignancy.