Macrophages of multiple sclerosis patients display deficient SHP-1 expression and enhanced inflammatory phenotype

Neuroimmune pathways involvement in neurodegeneration of R6/2 mouse model of Huntington's disease

Mechanisms of tissue damage in Huntington's disease (HD) involve excitotoxicity, mitochondrial damage, and neuroinflammation, including microglia activation. CD47 is a membrane protein that interacts with the inhibitory immunoreceptor SIRPα. Engagement of SIRPα by CD47 provides a downregulatory signal that inhibits host cell phagocytosis, promoting a "don't-eat-me" signal. These proteins are involved in the immune response and are downmodulated in inflammatory diseases. The involvement of inflammation and of the inflammasome in HD has already been described. In this study, we focused on other factors that can be involved in the unregulated inflammatory response that accelerates and exacerbate the neurodegenerative process in HD. Our results show that CD47 on striatal neurons decreased in HD mice, while it increased in wild type mice with age. SIRPα, on the other hand, was present in neurons in the wild type and increases in the R6/2 mice at all stages. Recruitment of SIRPα and binding to CD47 promotes the activation through phosphorylating events of non-receptor protein tyrosine phosphatase SHP-1 and SHP-2 in neurons and microglia. SHP phosphatases are able to curb the activity of NLRP3 inflammasome thereby reducing the detrimental effect of neuroinflammation. Such activity is mediated by the inhibition (dephosphorylation) of the proteins signal transducer and activator of transcription (STAT). We found that activated SHP-1 was present in microglia and neurons of WT mice at 5 and 13 weeks, increasing with time; while in R6/2 it was not localized in neurons but only in microglia, where it decreases with time. Consequently, STAT1 was overexpressed in neurons of R6/2 mice, as an effect of lack of modulation by SHP-1. Thus, our results shed light on the pathophysiology of neuronal damage, on one hand, paving the way toward a modulation of signal transducer proteins by specific inhibitors to achieve neuroprotection in HD, on the other.

Double-edged sword of JAK/STAT signaling pathway in viral infections: novel insights into virotherapy

The Janus kinase/signal transducer and activator of transcription (JAK/STAT) is an intricate signaling cascade composed of various cytokines, interferons (IFN, growth factors, and other molecules. This pathway provides a delicate mechanism through which extracellular factors adjust gene expression, thereby acting as a substantial basis for environmental signals to influence cell growth and differentiation. The interactions between the JAK/STAT cascade and antiviral IFNs are critical to the host's immune response against viral microorganisms. Recently, with the emergence of therapeutic classes that target JAKs, the significance of this  cascade has been recognized in an unprecedented way. Despite the functions of the JAK/STAT pathway in adjusting immune responses against viral pathogens, a vast body of evidence proposes the role of this cascade in the replication and pathogenesis of viral pathogens. In this article, we review the structure of the JAK/STAT signaling cascade and its role in immuno-inflammatory responses. We also highlight the paradoxical effects of this pathway in the pathogenesis of viral infections. Video Abstract.

Targeting pathogenic macrophages by the application of SHP-1 agonists reduces inflammation and alleviates pulmonary fibrosis

Idiopathic pulmonary fibrosis is a progressive fibrotic disorder with no cure that is characterized by deterioration of lung function. Current FDA-approved drugs for IPF delay the decline in lung function, but neither reverse fibrosis nor significantly improve overall survival. SHP-1 deficiency results in hyperactive alveolar macrophages accumulating in the lung, which contribute to the induction of pulmonary fibrosis. Herein, we investigated whether employing a SHP-1 agonist ameliorates pulmonary fibrosis in a bleomycin-induced pulmonary fibrosis murine model. Histological examination and micro-computed tomography images showed that SHP-1 agonist treatment alleviates bleomycin-induced pulmonary fibrosis. Reduced alveolar hemorrhage, lung inflammation, and collagen deposition, as well as enhanced alveolar space, lung capacity, and improved overall survival were observed in mice administered the SHP-1 agonist. The percentage of macrophages collected from bronchoalveolar lavage fluid and circulating monocytes in bleomycin-instilled mice were also significantly reduced by SHP-1 agonist treatment, suggesting that the SHP-1 agonist may alleviate pulmonary fibrosis by targeting macrophages and reshaping the immunofibrotic niche. In human monocyte-derived macrophages, SHP-1 agonist treatment downregulated CSF1R expression and inactivated STAT3/NFκB signaling, culminating in inhibited macrophage survival and perturbed macrophage polarization. The expression of pro-fibrotic markers (e.g., MRC1, CD200R1, and FN1) by IL4/IL13-induced M2 macrophages that rely on CSF1R signaling for their fate-determination was restricted by SHP-1 agonist treatment. While M2-derived medium promoted the expression of fibroblast-to-myofibroblast transition markers (e.g., ACTA2 and COL3A1), the application of SHP-1 agonist reversed the transition in a dose-dependent manner. Our report indicates that pharmacological activation of SHP-1 ameliorates pulmonary fibrosis via suppression of CSF1R signaling in macrophages, reduction of pathogenic macrophages, and the inhibition of fibroblast-to-myofibroblast transition. Our study thus identifies SHP-1 as a druggable target for the treatment of IPF, and suggests that the SHP-1 agonist may be developed as an anti-pulmonary fibrosis medication that both suppresses inflammation and restrains fibroblast-to-myofibroblast transition.

Targeting protein phosphatases in cancer immunotherapy and autoimmune disorders

Protein phosphatases act as key regulators of multiple important cellular processes and are attractive therapeutic targets for various diseases. Although extensive effort has been dedicated to phosphatase-targeted drug discovery, early expeditions for competitive phosphatase inhibitors were plagued by druggability issues, leading to the stigmatization of phosphatases as difficult targets. Despite challenges, persistent efforts have led to the identification of several drug-like, non-competitive modulators of some of these enzymes - including SH2 domain-containing protein tyrosine phosphatase 2, protein tyrosine phosphatase 1B, vascular endothelial protein tyrosine phosphatase and protein phosphatase 1 - reigniting interest in therapeutic targeting of phosphatases. Here, we discuss recent progress in phosphatase drug discovery, with emphasis on the development of selective modulators that exhibit biological activity. The roles and regulation of protein phosphatases in immune cells and their potential as powerful targets for immuno-oncology and autoimmunity indications are assessed.

Repair of Limb Ischemia Is Dependent on Hematopoietic Stem Cell Specific-SHP-1 Regulation of TGF-β1

BACKGROUND

Hematopoietic stem cell (HSC) therapy has shown promise for tissue regeneration after ischemia. Therefore, there is a need to understand mechanisms underlying endogenous HSCs activation in response to ischemic stress and coordination of angiogenesis and repair. SHP-1 plays important roles in HSC quiescence and differentiation by regulation of TGF-β1 signaling. TGF-β1 promotes angiogenesis by stimulating stem cells to secrete growth factors to initiate the formation of blood vessels and later aid in their maturation. We propose that SHP-1 responds to ischemia stress in HSC and progenitor cells (HSPC) via regulation of TGF-β1.

METHODS

A mouse hind limb ischemia model was used. Local blood perfusion in the limbs was determined using laser doppler perfusion imaging. The number of positive blood vessels per square millimeter, as well as blood vessel diameter (μm) and area (μm²), were calculated. Hematopoietic cells were analyzed using flow cytometry. The bone marrow transplantation assay was performed to measure HSC reconstitution.

RESULTS

After femoral artery ligation, TGF-β1 was initially decreased in the bone marrow by day 3 of ischemia, followed by an increase on day 7. This pattern was opposite to that in the peripheral blood, which is concordant with the response of HSC to ischemic stress. In contrast, SHP-1 deficiency in HSC is associated with irreversible activation of HSPCs in the bone marrow and increased circulating HSPCs in peripheral blood following limb ischemia. In addition, there was augmented auto-induction of TGF-β1 and sustained inactivation of SHP-1-Smad2 signaling, which impacted TGF-β1 expression in HSPCs in circulation. Importantly, restoration of normal T GF-β1 oscillations helped in the recovery of limb repair and function.

CONCLUSIONS

HSPC-SHP-1-mediated regulation of TGF-β1 in both bone marrow and peripheral blood is required for a normal response to ischemic stress.

Dexamethasone and Fumaric Acid Ester Conjugate Synergistically Inhibits Inflammation and NF-κB in Macrophages

Macrophage-mediated inflammation drives autoimmune and chronic inflammatory diseases. Treatment with anti-inflammatory agents can be an effective strategy to reduce this inflammation; however, high concentrations of these agents can have immune-dampening and other serious side effects. Synergistic combination of anti-inflammatory agents can mitigate dosing by requiring less drug. Multiple anti-inflammatory agents were evaluated in combination for synergistic inhibition of macrophage inflammation. The most potent synergy was observed between dexamethasone (DXM) and fumaric acid esters (e.g., monomethyl fumarate (MMF)). Furthermore, this combination was found to synergistically inhibit inflammatory nuclear factor κB (NF-κB) transcription factor activity. The optimal ratio for synergy was determined to be 1:1, and DXM and MMF were conjugated by esterification at this molar ratio. The DXM-MMF conjugate displayed improved inhibition of inflammation over the unconjugated combination in both murine and human macrophages. In the treatment of human donor monocyte-derived macrophages, the combination of DXM and MMF significantly inhibited inflammatory gene expression downstream of NF-κB and overall performed better than either agent alone. Further, the DXM-MMF conjugate significantly inhibited expression of NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome-associated genes. The potent anti-inflammatory activity of the DXM-MMF conjugate in human macrophages indicates that it may have benefits in the treatment of autoimmune and inflammatory diseases.

Toll-Like Receptors Gene Polymorphisms in Autoimmune Disease

Toll-like receptors (TLRs) are important initiators of the immune response, both innate and acquired. Evidence suggests that gene polymorphisms within TLRs cause malfunctions of certain key TLR-related signaling pathways, which subsequently increases the risk of autoimmune diseases. We illustrate and discuss the current findings on the role of Toll-like receptor gene polymorphisms in numerous autoimmune diseases in this review, such as type 1 diabetes mellitus, Graves’ disease, rheumatoid arthritis, systemic lupus erythematosus and multiple sclerosis. The study of genetic variation in TLRs in different populations has shown a complex interaction between immunity and environmental factors. This interaction suggests that TLR polymorphisms affect the susceptibility to autoimmune diseases differently in various populations. The identification of Toll-like receptor gene polymorphisms can expand our understanding of the pathogenesis of autoimmune diseases, which will subsequently guide effective medical management and provide insight into prognosis and advanced treatments.

Helicobacter pylori CagA Interacts with SHP-1 to Suppress the Immune Response by Targeting TRAF6 for K63-Linked Ubiquitination

Helicobacter pylori is the major etiological agent for most gastric cancer. CagA has been reported to be an important virulence factor of H. pylori, but its effect on the immune response is not yet clear. In this study, wild-type C57BL/6 mice and Ptpn6^me-v/me-v mice were randomly assigned for infection with H. pylori We demonstrated that CagA suppressed H. pylori-stimulated expression of proinflammatory cytokines in vivo. Besides, we infected mouse peritoneal macrophages RAW264.7 and AGS with H. pylori Our results showed that CagA suppressed expression of proinflammatory cytokines through inhibiting the MAPKs and NF-κB pathways activation in vitro. Mechanistically, we found that CagA interacted with the host cellular tyrosine phosphatase SHP-1, which facilitated the recruitment of SHP-1 to TRAF6 and inhibited the K63-linked ubiquitination of TRAF6, which obstructed the transmission of signal downstream. Taken together, these findings reveal a previously unknown mechanism by which CagA negatively regulates the posttranslational modification of TRAF6 in innate antibacterial immune response and provide molecular basis for new therapeutics to treat microbial infection.

Phosphatases in toll-like receptors signaling: the unfairly-forgotten

Over the past 2 decades, pattern recognition receptors (PRRs) have been shown to be on the front line of many illnesses such as autoimmune, inflammatory, and neurodegenerative diseases as well as allergies and cancer. Among PRRs, toll-like receptors (TLRs) are the most studied family. Dissecting TLRs signaling turned out to be advantageous to elaborate efficient treatments to cure autoimmune and chronic inflammatory disorders. However, a broad understanding of TLR effectors is required to propose a better range of cures. In addition to kinases and E3 ubiquitin ligases, phosphatases emerge as important regulators of TLRs signaling mediated by NF-κB, type I interferons (IFN I) and Mitogen-Activated Protein Kinases signaling pathways. Here, we review recent knowledge on TLRs signaling modulation by different classes and subclasses of phosphatases. Thus, it becomes more and more evident that phosphatases could represent novel therapeutic targets to control pathogenic TLRs signaling. Video Abstract.

Macrophage reprogramming for therapy

Dysfunction of the immune system underlies a plethora of human diseases, requiring the development of immunomodulatory therapeutic intervention. To date, most strategies employed have been focusing on the modification of T lymphocytes, and although remarkable improvement has been obtained, results often fall short of the intended outcome. Recent cutting-edge technologies have highlighted macrophages as potential targets for disease control. Macrophages play central roles in development, homeostasis and host defence, and their dysfunction and dysregulation have been implicated in the onset and pathogenesis of multiple disorders including cancer, neurodegeneration, autoimmunity and metabolic diseases. Recent advancements have led to a greater understanding of macrophage origin, diversity and function, in both health and disease. Over the last few years, a variety of strategies targeting macrophages have been developed and these open new therapeutic opportunities. Here, we review the progress in macrophage reprogramming in various disorders and discuss the potential implications and challenges for macrophage-targeted approaches in human disease.

Causal network inference from gene transcriptional time-series response to glucocorticoids

Gene regulatory network inference is essential to uncover complex relationships among gene pathways and inform downstream experiments, ultimately enabling regulatory network re-engineering. Network inference from transcriptional time-series data requires accurate, interpretable, and efficient determination of causal relationships among thousands of genes. Here, we develop Bootstrap Elastic net regression from Time Series (BETS), a statistical framework based on Granger causality for the recovery of a directed gene network from transcriptional time-series data. BETS uses elastic net regression and stability selection from bootstrapped samples to infer causal relationships among genes. BETS is highly parallelized, enabling efficient analysis of large transcriptional data sets. We show competitive accuracy on a community benchmark, the DREAM4 100-gene network inference challenge, where BETS is one of the fastest among methods of similar performance and additionally infers whether causal effects are activating or inhibitory. We apply BETS to transcriptional time-series data of differentially-expressed genes from A549 cells exposed to glucocorticoids over a period of 12 hours. We identify a network of 2768 genes and 31,945 directed edges (FDR ≤ 0.2). We validate inferred causal network edges using two external data sources: Overexpression experiments on the same glucocorticoid system, and genetic variants associated with inferred edges in primary lung tissue in the Genotype-Tissue Expression (GTEx) v6 project. BETS is available as an open source software package at https://github.com/lujonathanh/BETS.

Functional and metabolic characteristics of peripheral blood mononuclear phagocytes in patients with different clinical courses of multiple sclerosis

Functional and metabolic features of intact and stimulated mononuclear phagocytes were studied in patients with different clinical courses of multiple sclerosis, the study included 66 patients with relapsing-remitting and 32 patients with progressive course of multiple sclerosis. The state of the mononuclear phagocytes was characterized by expression of costimulatory molecules and direction of L-arginine metabolism. Relative quantities of CD80, CD86 and PD-L1 positive monocytes were determined with Phycoerytrin-labeled monoclonal antibodies in immunofluorescence test in peripheral blood and after culture in parallel series with addition of: (a) E.coli lipopolysaccharide (a stimulator of TLR4), (b) a single-stranded RNA – preparation ssRNA40/LyoVec (a stimulator of TLR7/8), (c) IL-4 (an anti-inflammatory interleukin). The formation of NO was determined by the amount of nitrite in the culture supernatants, arginase activity was determined in cell lysates of the monocyte fraction. We showed that functional and phenotypic characteristics of monocytes depend on the clinical course of multiple sclerosis. In patients with progressive course, the relative number of CD86+ cells was significantly higher and PD-L1+ cells significantly lower than in patients with relapsing-remitting course and healthy persons, in patients with relapsing-remitting course the number of PD-L1+ cells was increased. The number of CD80+ cells did not show any significant difference in the investigated groups of patients relative to the control group. In vitro stimulation of peripheral blood monocytes with TLR4/8 produced a significant increase in the number of CD86+ and decrease in the number of PD-L1+ cells in patients with the progressive course. In patients with the relapsing-remitting course LPS produced an increase in number of PD-L1+ cells. We did not find any difference in activity of the arginase pathway of L-arginine metabolism in the intact monocyte fraction of peripheral blood in patients with multiple sclerosis versus the control group, but stimulation with TLR4 agonist of mononuclear cells of patients with progressive course caused significant increased arginase activity versus baseline. At the same time, versus control cells arginase activity in patients with the progressive course decreased after LPS treatment, but trended to increase after TLR7/8 treatment. In patients with the relapsing-remitting course these changes had a similar direction but were less expressed. The results may be considered as an indication of the activation of peripheral blood monocytes and their polarization trend in the M1 direction in patients with the progressive course of multiple sclerosis, these changes could be considered as signs of violation of autoimmune regulatory mechanisms in multiple sclerosis.

Shp1 Loss Enhances Macrophage Effector Function and Promotes Anti-Tumor Immunity

Shp1, encoded by the gene Ptpn6, is a protein tyrosine phosphatase that transduces inhibitory signals downstream of immunoreceptors in many immune cell types. Blocking Shp1 activity represents an exciting potential immunotherapeutic strategy for the treatment of cancer, as Shp1 inhibition would be predicted to unleash both innate and adaptive immunity against tumor cells. Antibodies blocking the interaction between CD47 on tumor cells and SIRPα on macrophages enhance macrophage phagocytosis, show efficacy in preclinical tumor models, and are being evaluated in the clinic. Here we found that Shp1 bound to phosphorylated peptide sequences derived from SIRPα and transduced the anti-phagocytic signal, as Shp1 loss in mouse bone marrow-derived macrophages increased phagocytosis of tumor cells in vitro. We also generated a novel mouse model to evaluate the impact of global, inducible Ptpn6 deletion on anti-tumor immunity. We found that inducible Shp1 loss drove an inflammatory disease in mice that was phenotypically similar to that seen when Ptpn6 is knocked out from birth. This indicates that acute perturbation of Shp1 in vivo could drive hyperactivation of immune cells, which could be therapeutically beneficial, though at the risk of potential toxicity. In this model, we found that Shp1 loss led to robust anti-tumor immunity against two immune-rich syngeneic tumor models that are moderately inflamed though not responsive to checkpoint inhibitors, MC38 and E0771. Shp1 loss did not promote anti-tumor activity in the non-inflamed B16F10 model. The observed activity in MC38 and E0771 tumors was likely due to effects of both innate and adaptive immune cells. Following Shp1 deletion, we observed increases in intratumoral myeloid cells in both models, which was more striking in E0771 tumors. E0771 tumors also contained an increased ratio of effector to regulatory T cells following Shp1 loss. This was not observed for MC38 tumors, though we did find increased levels of IFNγ, a cytokine produced by effector T cells, in these tumors. Overall, our preclinical data suggested that targeting Shp1 may be an attractive therapeutic strategy for boosting the immune response to cancer via a mechanism involving both innate and adaptive leukocytes.

SHP-1 suppresses the antiviral innate immune response by targeting TRAF3

Type I interferons play a pivotal role in innate immune response to virus infection. The protein tyrosine phosphatase SHP‐1 was reported to function as a negative regulator of inflammatory cytokine production by inhibiting activation of NF‐κB and MAPKs during bacterial infection, however, the role of SHP‐1 in regulating type I interferons remains unknown. Here, we demonstrated that knockout or knockdown of SHP‐1 in macrophages promoted both HSV‐1‐ and VSV‐induced antiviral immune response. Conversely, overexpression of SHP‐1 in L929 cells suppressed the HSV‐1‐ and VSV‐induced immune response; suppression was directly dependent on phosphatase activity. We identified a direct interaction between SHP‐1 and TRAF3; the association between these two proteins resulted in diminished recruitment of CK1ε to TRAF3 and inhibited its K63‐linked ubiquitination; SHP‐1 inhibited K63‐linked ubiquitination of TRAF3 by promoting dephosphorylation at Tyr116 and Tyr446. Taken together, our results identify SHP‐1 as a negative regulator of antiviral immunity and suggest that SHP‐1 may be a target for intervention in acute virus infection.

Ets-2 deletion in myeloid cells attenuates IL-1α-mediated inflammatory disease caused by a Ptpn6 point mutation

The SHP-1 protein encoded by the Ptpn6 gene has been extensively studied in hematopoietic cells in the context of inflammation. A point mutation in this gene (Ptpn6^spin) causes spontaneous inflammation in mice, which has a striking similarity to neutrophilic dermatoses in humans. Recent findings highlighted the role of signaling adapters and kinases in promoting inflammation in Ptpn6^spin mice; however, the underlying transcriptional regulation is poorly understood. Here, we report that SYK is important for driving neutrophil infiltration and initiating wound healing responses in Ptpn6^spin mice. Moreover, we found that deletion of the transcription factor Ets2 in myeloid cells ameliorates cutaneous inflammatory disease in Ptpn6^spin mice through transcriptional regulation of its target inflammatory genes. Furthermore, Ets-2 drives IL-1α-mediated inflammatory signaling in neutrophils of Ptpn6^spin mice. Overall, in addition to its well-known role in driving inflammation in cancer, Ets-2 plays a major role in regulating IL-1α-driven Ptpn6^spin-mediated neutrophilic dermatoses. Model for the role of ETS-2 in neutrophilic inflammation in Ptpn6^spin mice. Mutation of the Ptpn6 gene results in SYK phosphorylation which then sequentially activates MAPK signaling pathways and activation of ETS-2. This leads to activation of ETS-2 target genes that contribute to neutrophil migration and inflammation. When Ets2 is deleted in Ptpn6^spin mice, the expression of these target genes is reduced, leading to the reduced pathology in neutrophilic dermatoses.

The Role of Monocytes and Macrophages in Autoimmune Diseases: A Comprehensive Review

Monocytes (Mo) and macrophages (Mϕ) are key components of the innate immune system and are involved in regulation of the initiation, development, and resolution of many inflammatory disorders. In addition, these cells also play important immunoregulatory and tissue-repairing roles to decrease immune reactions and promote tissue regeneration. Several lines of evidence have suggested a causal link between the presence or activation of these cells and the development of autoimmune diseases. In addition, Mo or Mϕ infiltration in diseased tissues is a hallmark of several autoimmune diseases. However, the detailed contributions of these cells, whether they actually initiate disease or perpetuate disease progression, and whether their phenotype and functional alteration are merely epiphenomena are still unclear in many autoimmune diseases. Additionally, little is known about their heterogeneous populations in different autoimmune diseases. Elucidating the relevance of Mo and Mϕ in autoimmune diseases and the associated mechanisms could lead to the identification of more effective therapeutic strategies in the future.

Targeted SHP-1 Silencing Modulates the Macrophage Phenotype, Leading to Metabolic Improvement in Dietary Obese Mice

Chronic over-nutrition promotes adipocyte hypertrophy that creates inflammatory milieu leading to macrophage infiltration and their phenotypic switching during obesity. The SH2 domain-containing protein tyrosine phosphatase 1 (SHP-1) has been identified as an important player in inflammatory diseases involving macrophages. However, the role of SHP-1 in modulating the macrophage phenotype has not been elucidated yet. In the present work, we show that adipose tissue macrophage (ATM)-specific deletion of SHP-1 using glucan particle-loaded siRNA improves the metabolic phenotype in dietary obese insulin-resistant mice. The molecular mechanism involves AT remodeling via reducing crown-like structure formation and balancing the pro-inflammatory (M1) and anti-inflammatory macrophage (M2) population. Therefore, targeting ATM-specific SHP-1 using glucan-particle-loaded SHP-1 antagonists could be of immense therapeutic use for the treatment of obesity-associated insulin resistance.

Tryptophan and arginine catabolic enzymes and regulatory cytokines in clinically isolated syndrome and multiple sclerosis

Objectives

Clinically isolated syndrome (CIS) is the earliest clinical episode in multiple sclerosis (MS). A study of circulating cells from patients with CIS may help us understand the transition to, and processes associated with, the development of MS.

Methods

As immune cell activity can be determined by flux through metabolic pathways, the mRNA expression of l‐tryptophan‐ and l‐arginine‐catabolising enzymes, indoleamine 2,3‐dioxygenase (IDO) 1 and IDO2 and arginase (ARG) 1 and ARG2, respectively, was compared between peripheral blood mononuclear cells (PBMCs) from healthy controls, and patients with CIS and definite MS. As one measure of cell function, cytokine mRNA levels were analysed directly ex vivo and in cells after culture for 4 h in the absence of regulatory factors in autologous serum.

Results

When measured directly ex vivo, the expression of IDO and ARG was greater in cells from patients with CIS and MS than cells from healthy controls. Although not linked to IDO and ARG expression, PBMCs from the CIS patients were characterised by low IL‐10 and TGFB mRNA levels and not by greater expression of proinflammatory cytokines. When the cells were cultured for 4 h without autologous serum, pro‐ and anti‐inflammatory cytokine mRNA levels positively correlated with IDO1 expression, and TGFB mRNA levels correlated with ARG1 expression.

Conclusion

Higher IDO and ARG expression in CIS and MS provides one sustained homeostatic mechanism to control MS‐associated inflammation. However, potent extrinsic mediators in serum may regulate immune cell function in CIS and associations between IDO, ARG and cytokine expression.

Role of the JAK/STAT signaling pathway in regulation of innate immunity in neuroinflammatory diseases

The Janus Kinase/Signal Transducers and Activators of Transcription (JAK/STAT) signaling pathway is utilized by numerous cytokines and interferons, and is essential for the development and function of both innate and adaptive immunity. Aberrant activation of the JAK/STAT pathway is evident in neuroinflammatory diseases such as Multiple Sclerosis and Parkinson's Disease. Innate immunity is the front line defender of the immune system and is composed of various cell types, including microglia, macrophages and neutrophils. Innate immune responses have both pathogenic and protective roles in neuroinflammation, depending on disease context and the microenvironment in the central nervous system. In this review, we discuss the role of innate immunity in the pathogenesis of neuroinflammatory diseases, how the JAK/STAT signaling pathway regulates the innate immune response, and finally, the potential for ameliorating neuroinflammation by utilization of JAK/STAT inhibitors.

Protein tyrosine phosphatase SHP-1: resurgence as new drug target for human autoimmune disorders

Recognition of self-antigen and its destruction by the immune system is the hallmark of autoimmune diseases. During the developmental stages, immune cells are introduced to the self-antigen, for which tolerance develops. The inflammatory insults that break the immune tolerance provoke immune system against self-antigen, progressively leading to autoimmune diseases. SH2 domain containing protein tyrosine phosphatase (PTP), SHP-1, was identified as hematopoietic cell-specific PTP that regulates immune function from developing immune tolerance to mediating cell signaling post-immunoreceptor activation. The extensive research on SHP-1-deficient mice elucidated the diversified role of SHP-1 in immune regulation, and inflammatory process and related disorders such as cancer, autoimmunity, and neurodegenerative diseases. The present review focalizes upon the implication of SHP-1 in the pathogenesis of autoimmune disorders, such as allergic asthma, neutrophilic dermatosis, atopic dermatitis, rheumatoid arthritis, and multiple sclerosis, so as to lay the background in pursuance of developing therapeutic strategies targeting SHP-1. Also, new SHP-1 molecular targets have been suggested like SIRP-α, PIPKIγ, and RIP-1 that may prove to be the focal point for the development of therapeutic strategies.

Therapeutic potential of curcumin for multiple sclerosis

Multiple sclerosis (MS) is a chronic autoimmune inflammatory disease of the central nervous system (CNS), characterized by demyelination, neuronal injury, and breaching of the blood-brain barrier (BBB). Epidemiological studies have shown that immunological, genetic, and environmental factors contribute to the progression and development of MS. T helper 17 (Th17) cells are crucial immunological participant in the pathophysiology of MS. The aberrant production of IL-17 and IL-22 by Th17 cells crosses BBB promotes its disruption and interferes with transmission of nerve signals through activation of neuroinflammation in the CNS. These inflammatory responses promote demyelination through transcriptional activation of signal transducers and activators of transcription-1 (STAT-1), nuclear factor kappa-B (NF-κB), matrix metalloproteinases (MMPs), interferon ϒ (IFNϒ), and Src homology region 2 domain-containing phosphatase-1 (SHP-1). B cells also contribute to disease progression through abnormal regulation of antibodies, cytokines, and antigen presentation. Additionally, oxidative stress has been known as a causative agent for the MS. Curcumin is a hydrophobic yellowish diphenolic component of turmeric, which can interact and modulate multiple cell signaling pathways and prevent the development of various autoimmune neurological diseases including MS. Studies have reported curcumin as a potent anti-inflammatory, antioxidant agent that could modulate cell cycle regulatory proteins, enzymes, cytokines, and transcription factors in CNS-related disorders including MS. The current study summarizes the reported knowledge on therapeutic potential of curcumin against MS, with future indication as neuroprotective and neuropharmacological drug.

Shp1 function in myeloid cells

The motheaten mouse was first described in 1975 as a model of systemic inflammation and autoimmunity, as a result of immune system dysregulation. The phenotype was later ascribed to mutations in the cytoplasmic tyrosine phosphatase Shp1. This phosphatase is expressed widely throughout the hematopoietic system and has been shown to impact a multitude of cell signaling pathways. The determination of which cell types contribute to the different aspects of the phenotype caused by global Shp1 loss or mutation and which pathways within these cell types are regulated by Shp1 is important to further our understanding of immune system regulation. In this review, we focus on the role of Shp1 in myeloid cells and how its dysregulation affects immune function, which can impact human disease.

The expression of VDR mRNA but not NF-κB surprisingly decreased after vitamin D treatment in multiple sclerosis patients

BACKGROUND AND PURPOSE

The aim of this study was to investigate the expression levels of vitamin D receptor (VDR) and NF-κB mRNAs in vitamin D (VD) supplemented multiple sclerosis (MS) patients.

METHODS

RRMS patients received 50,000 IU vitamin D3/week as an intra-muscular injection for 2 months. Blood samples were obtained from 30 MS patients before and after VD supplementation and 32 healthy individuals, and then VDR and NF-κB mRNA levels were measured by real time PCR method and analyzed with independent and paired t-tests. Moreover, some correlations were performed between the expression levels of selected genes and some clinical features of MS and control groups.

RESULTS

Surprisingly, the expression level of VDR mRNA significantly decreased after 2 months supplementation with VD in our selected patients and in contrast, the level of serum 25(OH) D increased after supplementation. Although, we didn't find any significant difference in the expression level of NF-κB gene before and after treatment with VD, its expression significantly decreased in untreated MS cases compared with healthy controls.

CONCLUSION

In conclusion, we found some new evidences from the molecular mechanism of vitamin D effectiveness in MS treatment. Also, we need more functional studies to find the effect of VD on the expression level of VDR mRNA.

Protein tyrosine phosphatase SHP-1 modulates osteoblast differentiation through direct association with and dephosphorylation of GSK3β

SHP-1, the Src homology-2 (SH2) domain-containing phosphatase 1, is a cytosolic protein-tyrosine phosphatase (PTP) predominantly expressed in hematopoietic-derived cells. Previous studies have focused on the involvement of SHP-1 in osteoclastogenesis. Using primary cultured mouse fetal calvaria-derived osteoblasts as a model, this study aims to investigate the effects of SHP-1 on differentiation and mineralization of osteoblasts and elucidate the signaling pathways responsible for these effects. We found that osteoblasts treated by osteogenic media showed significant increase in SHP-1 expression, which contributed to osteoblastic differentiation and mineralization. Using immunoprecipitation assay, we found that a direct association between SHP-1 and glycogen synthase kinase (GSK)-3β could be detected in differentiated osteoblasts and was significantly inhibited by SHP-1 inhibitor NSC87877. Inhibition of SHP-1 activated GSK3β, thereby leading to suppression of osteoblast differentiation and mineralization, which could be rescued by the inhibitor of GSK3β. In addition, we found that rosiglitazone (RSG) treatment led to significant decrease in SHP-1 expression. Overexpression of SHP-1 reversed RSG-induced GSK3β activation, thus rescuing the inhibitory effect of RSG on osteoblast differentiation and mineralization. These findings suggest that protein tyrosine phosphatase SHP-1 may act as a positive regulator of osteoblast differentiation through direct association with and dephosphorylation of GSK3β. Downregulation of SHP-1 may contribute to RSG-induced inhibition of mouse calvaria osteoblast differentiation by activating GSK3β-dependent pathway.

Macrophage polarization in response to oral commensals and pathogens

Macrophages have been identified in the periodontium. Data have phenotypically described these cells, demonstrated changes with progressing periodontal disease, and identified their ability to function in antigen-presentation critical for adaptive immune responses to individual oral bacterium. Recent evidence has emphasized an important role for the plasticity of macrophage phenotypes, not only in the resulting function of these cells in various tissues, but also clear differences in the stimulatory signals that result in M1 (classical activation, inflammatory) and M2 (alternative activation/deactivated, immunomodulatory) cells. This investigation hypothesized that the oral pathogens, Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans induce M1-type cells, while oral commensal bacteria primarily elicit macrophage functions consistent with an M2 phenotype. However, we observed that the M1 output from P. gingivalis challenge, showed exaggerated levels of pro-inflammatory cytokines, with a much lower production of chemokines related to T-cell recruitment. This contrasted with A. actinomycetemcomitans infection that increased both the pro-inflammatory cytokines and T-cell chemokines. Thus, it appears that P. gingivalis, as an oral pathogen, may have a unique capacity to alter the programming of the M1 macrophage resulting in a hyperinflammatory environment and minimizing the ability for T-cell immunomodulatory influx into the lesions.

Commentary: IL-4 and IL-13 receptors and signaling

Interleukin (IL)-4 and IL-13 were discovered approximately 30years ago and were immediately linked to allergy and atopic diseases. Since then, new roles for IL-4 and IL-13 and their receptors in normal gestation, fetal development and neurological function and in the pathogenesis of cancer and fibrosis have been appreciated. Studying IL-4/-13 and their receptors has revealed important clues about cytokine biology and led to the development of numerous experimental therapeutics. Here we aim to highlight new discoveries and consolidate concepts in the field of IL-4 and IL-13 structure, receptor regulation, signaling and experimental therapeutics.

The role of the ubiquitin-editing enzyme A20 in diseases of the central nervous system and other pathological processes

In recent years, the ubiquitin-editing enzyme A20 has been shown to control a large set of molecular pathways involved in the regulation of protective as well as self-directed immune responses. Here, we assess the current and putative roles of A20 in inflammatory, vascular and degenerative diseases of the central nervous system and explore future directions of research.

The control of reactive oxygen species production by SHP-1 in oligodendrocytes

We have previously described reduced myelination and corresponding myelin basic protein (MBP) expression in the central nervous system of Src homology 2 domain-containing protein tyrosine phosphatase 1 (SHP-1) deficient motheaten (me/me) mice compared with normal littermate controls. Deficiency in myelin and MBP expression in both brains and spinal cords of motheaten mice correlated with reduced MBP mRNA expression levels in vivo and in purified oligodendrocytes in vitro. Therefore, SHP-1 activity seems to be a critical regulator of oligodendrocyte gene expression and function. Consistent with this role, this study demonstrates that oligodendrocytes of motheaten mice and SHP-1-depleted N20.1 cells produce higher levels of reactive oxygen species (ROS) and exhibit corresponding markers of increased oxidative stress. In agreement with these findings, we demonstrate that increased production of ROS coincides with ROS-induced signaling pathways known to affect myelin gene expression in oligodendrocytes. Antioxidant treatment of SHP-1-deficient oligodendrocytes reversed the pathological changes in these cells, with increased myelin protein gene expression and decreased expression of nuclear factor (erythroid-2)-related factor 2 (Nrf2) responsive gene, heme oxygenase-1 (HO-1). Furthermore, we demonstrate that SHP-1 is expressed in human white matter oligodendrocytes, and there is a subset of multiple sclerosis subjects that demonstrate a deficiency of SHP-1 in normal-appearing white matter. These studies reveal critical pathways controlled by SHP-1 in oligodendrocytes that relate to susceptibility of SHP-1-deficient mice to both developmental defects in myelination and to inflammatory demyelinating diseases.

Cx3cr1 deficiency in mice attenuates hepatic granuloma formation during acute schistosomiasis by enhancing the M2-type polarization of macrophages

Acute schistosomiasis is characterized by pro-inflammatory responses against tissue- or organ-trapped parasite eggs along with granuloma formation. Here, we describe studies in Cx3cr1^−/− mice and demonstrate the role of Cx3cr1 in the pathoetiology of granuloma formation during acute schistosomiasis. Mice deficient in Cx3cr1 were protected from granuloma formation and hepatic injury induced by Schistosoma japonicum eggs, as manifested by reduced body weight loss and attenuated hepatomegaly along with preserved liver function. Notably, S. japonicum infection induced high levels of hepatic Cx3cr1 expression, which was predominantly expressed by infiltrating macrophages. Loss of Cx3cr1 rendered macrophages preferentially towards M2 polarization, which then led to a characteristic switch of the host immune defense from a conventional Th1 to a typical Th2 response during acute schistosomiasis. This immune switch caused by Cx3cr1 deficiency was probably associated with enhanced STAT6/PPAR-γ signaling and increased expression of indoleamine 2,3-dioxygenase (IDO), an enzyme that promotes M2 polarization of macrophages. Taken together, our data provide evidence suggesting that CX3CR1 could be a viable therapeutic target for treatment of acute schistosomiasis.

Highlighted Article: A reduction in CX3CR1 signaling provides protection for mice against pro-inflammatory responses and hepatic granuloma formation during acute schistosomiasis.

Schistosoma mansoni Soluble Egg Antigens Induce Expression of the Negative Regulators SOCS1 and SHP1 in Human Dendritic Cells via Interaction with the Mannose Receptor

Schistosomiasis is a common debilitating human parasitic disease in (sub)tropical areas, however, schistosome infections can also protect against a variety of inflammatory diseases. This has raised broad interest in the mechanisms by which Schistosoma modulate the immune system into an anti-inflammatory and regulatory state. Human dendritic cells (DCs) show many phenotypic changes upon contact with Schistosoma mansoni soluble egg antigens (SEA). We here show that oxidation of SEA glycans, but not heat-denaturation, abrogates the capacity of SEA to suppress both LPS-induced cytokine secretion and DC proliferation, indicating an important role of SEA glycans in these processes. Remarkably, interaction of SEA glycans with DCs results in a strongly increased expression of Suppressor Of Cytokine Signalling1 (SOCS1) and SH2-containing protein tyrosine Phosphatase-1 (SHP1), important negative regulators of TLR4 signalling. In addition, SEA induces the secretion of transforming growth factor β (TGF-β), and the surface expression of the costimulatory molecules Programmed Death Ligand-1 (PD-L1) and OX40 ligand (OX40L), which are known phenotypic markers for the capacity of DCs to polarize naïve T cells into Th2/Treg cell subsets. Inhibition of mannose receptor (MR)-mediated internalization of SEA into DCs by blocking with allyl α-D-mannoside or anti-MR antibodies, significantly reduced SOCS1 and SHP1 expression. In conclusion, we demonstrate that SEA glycans are essential for induction of enhanced SOCS1 and SHP1 levels in DCs via the MR. Our data provide novel mechanistic evidence for the potential of S. mansoni SEA glycans to modulate human DCs, which may contribute to the capacity of SEA to down-regulate inflammatory responses.

Taenia crassiceps infection and its excreted/secreted products inhibit STAT1 activation in response to IFN-γ

It is well understood that helminth infections modulate the immune responses of their hosts but the mechanisms involved in this modulation are not fully known. Macrophages and dendritic cells appear to be consistently affected during this type of infection and are common target cells for helminth-derived molecules. In this report, we show that macrophages obtained from chronically Taenia crassiceps-infected mice displayed an impaired response to recombinant murine IFN-γ, but not to recombinant murine IL-4, as measured based on the phosphorylation of STAT1 and STAT6, respectively. These macrophages expressed high levels of SOCS3. However, the inhibition of phosphatase activity by orthovanadate restored the IFN-γ response of these macrophages by increasing STAT1 phosphorylation without affecting SOCS3 expression. Therefore, we aimed to identify the phosphatases associated with IFN-γ signaling inhibition and found that macrophages from T. crassiceps-infected mice displayed enhanced SHP-1 expression. Interestingly, the exposure of naïve macrophages to T. crassiceps excreted/secreted products similarly interfered with IFN-γ-induced STAT1 phosphorylation. Moreover, macrophages exposed to T. crassiceps excreted/secreted products expressed high levels of SOCS3 as well as SHP-1. Strikingly, human peripheral blood mononuclear cells that were exposed to T. crassiceps excreted/secreted products in vitro also displayed impaired STAT1 phosphorylation in response to IFN-γ; again, phosphatase inhibition abrogated the T. crassiceps excreted/secreted product-altered IFN-γ signaling. These data demonstrate a new mechanism by which helminth infection and the products derived during this infection target intracellular pathways to block the response to inflammatory cytokines such as IFN-γ in both murine and human cells.

Gene expression profiles in granuloma tissue reveal novel diagnostic markers in sarcoidosis

Sarcoidosis is an immune-mediated multisystem disease characterized by the formation of non-caseating granulomas. The pathogenesis of sarcoidosis is unclear, with proposed infectious or environmental antigens triggering an aberrant immune response in susceptible hosts. Multiple pro-inflammatory signaling pathways have been implicated in mediating macrophage activation and granuloma formation in sarcoidosis, including IFN-γ/STAT-1, IL-6/STAT-3, and NF-κB. It is difficult to distinguish sarcoidosis from other granulomatous diseases or assess disease severity and treatment response with histopathology alone. Therefore, development of improved diagnostic tools is imperative. Herein, we describe an efficient and reliable technique to classify granulomatous disease through selected gene expression and identify novel genes and cytokine pathways contributing to the pathogenesis of sarcoidosis. We quantified the expression of twenty selected mRNAs extracted from formalin-fixed paraffin embedded (FFPE) tissue (n = 38) of normal lung, suture granulomas, sarcoid granulomas, and fungal granulomas. Utilizing quantitative real-time RT-PCR we analyzed the expression of several genes, including IL-6, COX-2, MCP-1, IFN-γ, T-bet, IRF-1, Nox2, IL-33, and eotaxin-1 and revealed differential regulation between suture, sarcoidosis, and fungal granulomas. This is the first study demonstrating that quantification of target gene expression in FFPE tissue biopsies is a potentially effective diagnostic and research tool in sarcoidosis.

Immune regulation of multiple sclerosis

Multiple sclerosis (MS) is considered a prototype inflammatory autoimmune disorder of the central nervous system (CNS). The etiology of this disease remains unknown, but an interplay between as yet unidentified environmental factors and susceptibility genes appears most likely. In consequence, these factors trigger a cascade, involving an inflammatory response within the CNS that results in demyelination, oligodendrocyte death, axonal damage, gliosis, and neurodegeneration. How these complex traits translate into the clinical presentation of the disease is a focus of ongoing research. The central hypothesis is that T lymphocytes with receptors for CNS myelin components are driving the disease. The initial activation of autoreactive lymphocytes is thought to take place in the systemic lymphoid organs, most likely through molecular mimickry or nonspecifically through bystander activation. These autoreactive lymphocytes can migrate to the CNS where they become reactivated upon encountering their target antigen, initiating an autoimmune inflammatory attack. This ultimately leads to demyelination and axonal damage. This chapter focuses on the role of T and B lymphocytes in the immunopathogenesis of MS.

Toll-like receptor 3 differently modulates inflammation in progressive or benign multiple sclerosis

TLR-dependent signal transduction pathways were analyzed in patients with a diagnosis of either relapsing-remitting (RRMS), secondary progressive (PMS) or benign (BMS) MS and healthy controls (HC). Prototypical TLR molecules expressed either on the cell surface (TLR4) or intracellularly (TLR3) were stimulated with specific antigens (LPS and poly I:C, respectively). Expression of factors involved in TLR signaling cascades, production of downstream immune mediators and TLR expression were evaluated. Results showed that, whereas LPS-stimulation of TLR4 had a marginal effect on cell activation, poly I:C-stimulated TLR3 expression on immune cells was significantly increased in PMS and BMS compared to HC. This was associated with a higher responsiveness to poly I:C that resulted in the activation of the TLR3-mediated pathway and the production of inflammatory cytokines in PMS and, in contrast, in the up-regulation of a peculiar mosaic of inflammation-dampening genes in BMS. Results herein might explain different MS disease phenotypes.

DJ-1 facilitates the interaction between STAT1 and its phosphatase, SHP-1, in brain microglia and astrocytes: A novel anti-inflammatory function of DJ-1

Parkinson's disease (PD) is a progressive neurodegenerative movement disorder caused by the death of dopaminergic neurons in the substantia nigra. Importantly, altered astrocyte and microglial functions could contribute to neuronal death in PD. In this study, we demonstrate a novel mechanism by which DJ-1 (PARK7), an early onset autosomal-recessive PD gene, negatively regulates inflammatory responses of astrocytes and microglia by facilitating the interaction between STAT1 and its phosphatase, SHP-1 (Src-homology 2-domain containing protein tyrosine phosphatase-1). Astrocytes and microglia cultured from DJ-1-knockout (KO) mice exhibited increased expression of inflammatory mediators and phosphorylation levels of STAT1 (p-STAT1) in response to interferon-gamma (IFN-γ) compared to cells from wild-type (WT) mice. DJ-1 deficiency also attenuated IFN-γ-induced interactions of SHP-1 with p-STAT1 and STAT1, measured 1 and 12h after IFN-γ treatment, respectively. Subsequent experiments showed that DJ-1 directly interacts with SHP-1, p-STAT1, and STAT1. Notably, DJ-1 bound to SHP-1 independently of IFN-γ, whereas the interactions of DJ-1 with p-STAT1 and STAT1 were dependent on IFN-γ. Similar results were obtained in brain slice cultures, where IFN-γ induced much stronger STAT1 phosphorylation and inflammatory responses in KO slices than in WT slices. Moreover, IFN-γ treatment induced neuronal damage in KO slices. Collectively, these findings suggest that DJ-1 may function as a scaffold protein that facilitates SHP-1 interactions with p-STAT1 and STAT1, thereby preventing extensive and prolonged STAT1 activation. Thus, the loss of DJ-1 function may increase the risk of PD by enhancing brain inflammation.

SHP-1 regulation of mast cell function in allergic inflammation and anaphylaxis

Allergic inflammation and severe allergic reactions (anaphylaxis) are important in allergen induced diseases. Bacterial products such as lipopolysaccharide (LPS) are ubiquitous and can facilitate allergen induced Th2 immune responses. Phosphatase SHP-1 is critical in regulating immunological homeostasis and in allergen induced Th2 immune responses in the lung. However, the mechanisms underlying the initiation of allergic inflammation and allergen induced anaphylaxis are still not completely elucidated and it is unclear whether SHP-1 plays any role in LPS-induced airway inflammation and in allergen-induced anaphylaxis. In this study we tested the hypothesis that phosphatase SHP-1 plays an important role in allergic inflammation and anaphylaxis and determined whether its effects are through regulation of mast cell functions. SHP-1 deficient (mev/+ and mev/mev) and mast cell deficient (Kit(W-sh)) mice were examined in their responses to LPS airway stimulation and to ovalbumin (OVA) allergen induced systemic anaphylaxis. Compared to wild type mice, mev/+ mice had significantly enhanced LPS induced airway inflammation and OVA induced anaphylactic responses, including hypothermia and clinical symptoms. These changes were mast cell dependent as Kit(W-sh) mice had reduced responses whereas adoptive transfer of mast cells restored the responses. However, T and B cells were not involved and macrophages did not play a significant role in LPS induced airway inflammation. Interestingly, basophil differentiation from SHP-1 deficient bone marrow cells was significantly reduced. These findings provided evidence that through regulation of mast cell functions SHP-1 plays a critical role as a negative regulator in allergic inflammation and in allergen induced anaphylaxis. In addition, SHP-1 seems to be required for normal basophil development.

Deficiency in hematopoietic phosphatase ptpn6/Shp1 hyperactivates the innate immune system and impairs control of bacterial infections in zebrafish embryos

Deficiency in Src homology region 2 domain-containing phosphatase 1/protein tyrosine phosphatase nonreceptor type 6 (SHP1/PTPN6) is linked with chronic inflammatory diseases and hematological malignancies in humans. In this study, we exploited the embryonic and larval stages of zebrafish (Danio rerio) as an animal model to study ptpn6 function in the sole context of innate immunity. We show that ptpn6 knockdown induces a spontaneous inflammation-associated phenotype at the late larval stage. Surprisingly, glucocorticoid treatment did not suppress inflammation under ptpn6 knockdown conditions but further enhanced leukocyte infiltration and proinflammatory gene expression. Experiments in a germ-free environment showed that the late larval phenotype was microbe independent. When ptpn6 knockdown embryos were challenged with Salmonella typhimurium or Mycobacterium marinum at earlier stages of development, the innate immune system was hyperactivated to a contraproductive level that impaired the control of these pathogenic bacteria. Transcriptome analysis demonstrated that Kyoto Encyclopedia of Genes and Genomes pathways related to pathogen recognition and cytokine signaling were significantly enriched under these conditions, suggesting that ptpn6 functions as a negative regulator that imposes a tight control over the level of innate immune response activation during infection. In contrast to the hyperinduction of proinflammatory cytokine genes under ptpn6 knockdown conditions, anti-inflammatory il10 expression was not hyperinduced. These results support that ptpn6 has a crucial regulatory function in preventing host-detrimental effects of inflammation and is essential for a successful defense mechanism against invading microbes.

Immune markers and differential signaling networks in ulcerative colitis and Crohn's disease

BACKGROUND

Cytokine signaling pathways play a central role in the pathogenesis of inflammatory bowel disease (IBD). Ulcerative colitis (UC) and Crohn's disease (CD) have unique as well as overlapping phenotypes, susceptibility genes, and gene expression profiles. This study aimed to delineate patterns within cytokine signaling pathways in colonic mucosa of UC and CD patients, explore molecular diagnostic markers, and identify novel immune mediators in IBD pathogenesis.

METHODS

We quantified 70 selected immune genes that are important in IBD signaling from formalin-fixed, paraffin-embedded (FFPE) colon biopsy samples from normal control subjects and UC and CD patients having either severe colitis or quiescent disease (n = 98 subjects). We utilized and validated a new modified real-time reverse-transcription polymerase chain reaction (RT-PCR) technique for gene quantification.

RESULTS

Expression levels of signaling molecules including IL-6/10/12/13/17/23/33, STAT1/3/6, T-bet, GATA3, Foxp3, SOCS1/3, and downstream inflammatory mediators such as chemokines CCL-2/11/17/20, oxidative stress inducers, proteases, and mucosal genes were differentially regulated between UC and CD and between active and quiescent disease. We also document the possible role of novel genes in IBD, including SHP-1, IRF-1,TARC, Eotaxin, NOX2, arginase I, and ADAM 8.

CONCLUSIONS

This comprehensive approach to quantifying gene expression provides insights into the pathogenesis of IBD by elucidating distinct immune signaling networks in CD and UC. Furthermore, this is the first study demonstrating that gene expression profiling in FFPE colon biopsies might be a practical and effective tool in the diagnosis and prognosis of IBD and may help identify molecular markers that can predict and monitor response to individualized therapeutic treatments.

Synthetic peptides containing ITIM-like domains block expression of inflammatory mediators and migration/invasion of cancer cells through activation of SHP-1 and PI3K

Increasing evidence supports that inflammation is closely associated with the development of cancer. In an effort to develop synthetic peptides that can suppress the inflammatory activation of cancer cells, decapeptides representing immunoreceptor tyrosine-based inhibitory motif (ITIM)-like sequences of immune receptor expressed on myeloid cells-1 (IREM-1) were tested for their anti-inflammatory effects in cancer cell lines. One (named TAT-YADL) out of the five synthetic peptides tested exhibited inhibitory effects on the expression of inflammatory mediators as well as invasion and migration. The inhibitory activities of the synthetic peptides required activation of SH2-containing protein tyrosine phosphatase-1 (SHP-1) and phosphoinositide 3-kinase (PI3K).

Identification of VHY/Dusp15 as a regulator of oligodendrocyte differentiation through a systematic genomics approach

Multiple sclerosis (MS) is a neuroinflammatory disease characterized by a progressive loss of myelin and a failure of oligodendrocyte (OL)-mediated remyelination, particularly in the progressive phases of the disease. An improved understanding of the signaling mechanisms that control differentiation of OL precursors may lead to the identification of new therapeutic targets for remyelination in MS. About 100 mammalian Protein Tyrosine Phosphatases (PTPs) are known, many of which are involved in signaling both in health and disease. We have undertaken a systematic genomic approach to evaluate PTP gene activity in multiple sclerosis autopsies and in related in vivo and in vitro models of the disease. This effort led to the identification of Dusp15/VHY, a PTP previously believed to be expressed only in testis, as being transcriptionally regulated during OL differentiation and in MS lesions. Subsequent RNA interference studies revealed that Dusp15/VHY is a key regulator of OL differentiation. Finally, we identified PDGFR-beta and SNX6 as novel and specific Dusp15 substrates, providing an indication as to how this PTP might exert control over OL differentiation.

Astaxanthin treatment reduced oxidative induced pro-inflammatory cytokines secretion in U937: SHP-1 as a novel biological target

It has been suggested that oxidative stress activates various intracellular signaling pathways leading to secretion of a variety of pro-inflammatory cytokines and chemokines. SHP-1 is a protein tyrosine phosphatase (PTP) which acts as a negative regulator of immune cytokine signaling. However, intracellular hydrogen peroxide (H₂O₂), generated endogenously upon stimulation and exogenously from environmental oxidants, has been known to be involved in the process of intracellular signaling through inhibiting various PTPs, including SHP-1. In this study, we investigated the potential role of astaxanthin, an antioxidant marine carotenoid, in re-establishing SHP-1 negative regulation on pro-inflammatory cytokines secretion in U-937 cell line stimulated with oxidative stimulus. ELISA measurement suggested that ASTA treatment (10 µM) reduced pro-inflammatory cytokines secretion (IL-1β, IL-6 and TNF-α) induced through H₂O₂, (100 µM). Furthermore, this property is elicited by restoration of basal SHP-1 protein expression level and reduced NF-κB (p65) nuclear expression, as showed by western blotting experiments.

Increased promoter methylation of the immune regulatory gene SHP-1 in leukocytes of multiple sclerosis subjects

The protein tyrosine phosphatase, SHP-1, is a negative regulator of proinflammatory signaling and autoimmune disease. We have previously reported reduced SHP-1 expression in peripheral blood leukocytes of subjects with multiple sclerosis (MS). Recent evidence indicates that virus-induced DNA methylation of the SHP-1 promoter is responsible for aberrant silencing of SHP-1 expression and function in hematopoietic cells that might relate to inflammatory diseases. In the present study, bisulfite sequencing of the SHP-1 promoter demonstrated that over a third of MS subjects had abnormally high promoter methylation. As SHP-1 is deficient in MS leukocytes and SHP-1-regulated proinflammatory genes are correspondingly upregulated, we propose that increased SHP-1 promoter methylation may relate in part to decreased SHP-1 expression and increased leukocyte-mediated inflammation in MS.

Synthetic peptides containing ITIM-like sequences of IREM-1 (CD300F) differentially regulate MyD88 and TRIF-mediated TLR signalling through activation of SHP and/or PI3K

The immune receptor expressed on myeloid cells 1 (IREM-1/CD300F) has been shown to inhibit various inflammatory processes in myeloid cells, such as macrophages and mast cells. IREM-1 exerts its inhibitory effect through its intracellular immunoreceptor tyrosine-based inhibition motifs (ITIMs). In order to generate immunomodulatory molecules that can regulate the inflammatory activation of macrophages, decapeptides representing each of the five ITIM-like sequences in the cytoplasmic tail of IREM-1 were synthesized in conjugation with human immunodeficiency virus-transactivator of transcription (HIV-TAT(48-57)), which was added to promote internalization of the peptides. Interestingly, all these TAT-ITIM fusion peptides inhibited Toll-like receptor (TLR)-mediated production of proinflammatory molecules, including matrix metalloproteinase (MMP)-9, tumour necrosis factor (TNF)-α, monocyte chemotactic protein-1 (MCP-1) and interleukin (IL)-8. When various TLR ligands were used to stimulate the human macrophage-like cell line human acute monocytic leukaemia cell line (THP)-1, the TAT-ITIM peptides blocked both myeloid differentiation factor 88 (MyD88) and Toll-interleukin 1 receptor (TIR)-domain-containing adapter-inducing interferon-β (TRIF)-mediated TLR signalling pathways. Utilization of specific inhibitors and detection of the active form of signalling adaptors by Western blot analysis further demonstrated that the inhibitory effects of these TAT-ITIM peptides require activation of Src homology 2 (SH2)-containing tyrosine phosphatase (SHP) and/or phosphoinositide 3-kinase (PI3K). These data indicate that these synthetic peptides may be used to regulate immune responses that involve TLR-mediated inflammatory activation of macrophages.

Interleukin-33 upregulation in peripheral leukocytes and CNS of multiple sclerosis patients

Multiple sclerosis (MS) is an immune-mediated demyelinating disease of the central nervous system (CNS). Here we document for the first time that the cytokine IL-33 is upregulated in both the periphery and the CNS of MS patients. Plasma IL-33 was elevated in MS patients compared to normal subjects and a three-month treatment of MS patients with interferon β-1a resulted in a significant decrease of IL-33 levels. Similarly, stimulated cultured lymphocytes and macrophages from MS patients had elevated IL-33 levels compared to normal subjects. In parallel, the transcription factor NF-κB that mediates IL-33 transcription was also elevated in leukocytes of MS patients. IL-33 was elevated in normal-appearing white matter and plaque areas from MS brains and astrocytes were identified as an important source of IL-33 expression in the CNS. In summary, IL-33 levels are elevated in the periphery and CNS of MS patients, implicating IL-33 in the pathogenesis of MS.