SOCS2-induced proteasome-dependent TRAF6 degradation: a common anti-inflammatory pathway for control of innate immune responses

A loss of function mutation in SOCS2 results in increased inflammatory response of macrophages to TLR ligands and Staphylococcus aureus

Introduction

The role of suppressor of cytokine signaling (SOCS)2 in anti-infective bacterial immunity has been poorly investigated compared to other members of the SOCS family.

Methods

We characterized the previously identified loss of function R96C point mutation of SOCS2 using a genome-edited mouse model that resumes the phenotype of Socs2 knockout mice. The response of macrophages to TLR-ligands and Staphylococcus aureus was examined.

Results and discussion

Conversely to previously published data using human monocyte-derived macrophages, the stimulation of bone-marrow-derived macrophages with various TLR ligands did not show any difference according to the SOCS2 variant. Upregulation of IL-6 and TNF-α pro-inflammatory cytokines production was only seen when the SOCS2 expression was promoted by the culture of macrophages in the presence of GM-CSF. Furthermore, we showed that the SOCS2 point mutation is associated with heightened STAT5 phosphorylation in a short time frame upon GM-CSF incubation. In mice, recruitment of neutrophil and F4/80int Ly6C+ inflammatory macrophage, as well as IFN-γ and IL-10 concentrations, are significantly increased upon S. aureus peritoneal infection. Altogether, these data support the idea that by lowering the pro-inflammatory environment, SOCS2 favors better control of bacterial burden during a systemic infection caused by S. aureus.

Outer membrane protein 25 of Brucella suppresses TLR-mediated expression of proinflammatory cytokines through degradation of TLRs and adaptor proteins

Toll-like receptors (TLRs) are essential components of innate immunity that serves as the first line of defense against the invaded microorganisms. However, successful infectious pathogens subvert TLR signaling to suppress the activation of innate and adaptive responses. Brucella species are infectious intracellular bacterial pathogens causing the worldwide zoonotic disease, brucellosis, that impacts economic growth of many countries. Brucella species are considered as stealthy bacterial pathogens as they efficiently evade or suppress host innate and adaptive immune responses for their chronic persistence. However, the bacterial effectors and their host targets for modulating the immune responses remain obscure. Brucella encodes various outer membrane proteins (Omps) that facilitate their invasion, intracellular replication, and immunomodulation. Outer membrane protein 25 (Omp25) of Brucella plays an important role in the immune modulation through suppression of proinflammatory cytokines. However, the mechanism and the signaling pathways that are targeted by Omp25 to attenuate the production of proinflammatory cytokines remain obscure. Here, we report that Omp25 and its variants, viz. Omp25b, Omp25c, and Omp25d, suppress production of proinflammatory cytokines that are mediated by various TLRs. Furthermore, we demonstrate that Omp25 and its variants promote enhanced ubiquitination and degradation of TLRs and their adaptor proteins to attenuate the expression of proinflammatory cytokines. Targeting multiple TLRs and adaptor proteins enables Omp25 to effectively suppress the expression of proinflammatory cytokines that are induced by diverse pathogen-associated molecular patterns. This can contribute to the defective adaptive immune response and the chronic persistence of Brucella in the host.

Edaravone dexborneol ameliorates cognitive impairment by regulating the NF-κB pathway through AHR and promoting microglial polarization towards the M2 phenotype in mice with bilateral carotid artery stenosis (BCAS)

Cerebral small vessel disease (CSVD) is one of the most important causes of stroke and vascular dementia, so exploring effective treatment modalities for CSVD is warranted. This study aimed to explore the anti-inflammatory effects of Edaravone dexborneol (C.EDA) in a CSVD model. Mice with CSVD showed distinct cognitive decline, as assessed by the Morris water maze (MWM). Pathological staining verified leakage across the blood‒brain barrier (BBB), microglial proliferation, neuronal loss and demyelination. Western blot analysis demonstrated that M1 microglia dominated prophase and released proinflammatory molecules; the aryl hydrocarbon receptor (AHR) was found to participate in modulating nuclear factor-kappa B (NF-κB) signalling activation through tumour necrosis factor receptor-associated factor-6 (TRAF6). C.EDA treatment resulted in the polarization of microglia from the M1 to the M2 phenotype. Mice sequentially treated with C.EDA exhibited a significant improvement in cognitive function; expression of the anti-inflammatory cytokines and modulatory proteins AHR and TRAF6 was upregulated, while the levels of pNF-κBp65 and pIΚBα were downregulated. C.EDA promoted microglial activation towards the M2 phenotype by upregulating AHR expression, which prevented TRAF6 ubiquitination, promoted NF-κB RelA/p65 protein degradation and inhibited subsequent NF-κB phosphorylation. Mechanistically, the anti-inflammatory effect of C.EDA alleviated neuronal loss and myelin damage, while at the functional level, C.EDA improved cognitive function and thus showed good application prospects.

Induction of Aryl Hydrocarbon Receptor-Mediated Cancer Cell-Selective Apoptosis in Triple-Negative Breast Cancer Cells by a High-Affinity Benzimidazoisoquinoline

Triple-negative breast cancer (TNBC) remains a disease with a paucity of targeted treatment opportunities. The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that is involved in a wide range of physiological processes, including the sensing of xenobiotics, immune function, development, and differentiation. Different small-molecule AhR ligands drive strikingly varied cellular and organismal responses. In certain cancers, AhR activation by select small molecules induces cell cycle arrest or apoptosis via activation of tumor-suppressive transcriptional programs. AhR is expressed in triple-negative breast cancers, presenting a tractable therapeutic opportunity. Here, we identify a novel ligand of the aryl hydrocarbon receptor that potently and selectively induces cell death in triple-negative breast cancer cells and TNBC stem cells via the AhR. Importantly, we found that this compound, Analog 523, exhibits minimal cytotoxicity against multiple normal human primary cells. Analog 523 represents a high-affinity AhR ligand with potential for future clinical translation as an anticancer agent.

SOCS2 regulates alveolar bone loss in Aggregatibacter actinomycetemcomitans-induced periodontal disease

INTRODUCTION

The role of suppressor of cytokine signaling 2 (SOCS2) in Aggregatibacter actinomycetemcomitans (Aa)-induced alveolar bone loss is unknown; thus, it was investigated in this study.

METHODS

Alveolar bone loss was induced by infecting C57BL/6 wild-type (WT) and Socs2-knockout (Socs2^-/-) mice with Aa. Bone parameters, bone loss, bone cell counts, the expression of bone remodeling markers, and cytokine profile were evaluated by microtomography, histology, qPCR, and/or ELISA. Bone marrow cells (BMC) from WT and Socs2^-/- mice were differentiated in osteoblasts or osteoclasts for analysis of the expression of specific markers.

RESULTS

Socs2^-/- mice intrinsically exhibited irregular phenotypes in the maxillary bone and an increased number of osteoclasts. Upon Aa infection, SOCS2 deficiency resulted in the increased alveolar bone loss, despite decreased proinflammatory cytokine production, in comparison to the WT mice. In vitro, SOCS2 deficiency resulted in the increased osteoclasts formation, decreased expression of bone remodeling markers, and proinflammatory cytokines after Aa-LPS stimulus.

CONCLUSIONS

Collectively, data suggest that SOCS2 is a regulator of Aa-induced alveolar bone loss by controlling the differentiation and activity of bone cells, and proinflammatory cytokines availability in the periodontal microenvironment and an important target for new therapeutic strategies. Thus, it can be helpful in preventing alveolar bone loss in periodontal inflammatory conditions.

Microbial Tryptophan Metabolism Tunes Host Immunity, Metabolism, and Extraintestinal Disorders

The trillions of commensal microorganisms comprising the gut microbiota have received growing attention owing to their impact on host physiology. Recent advances in our understandings of the host–microbiota crosstalk support a pivotal role of microbiota-derived metabolites in various physiological processes, as they serve as messengers in the complex dialogue between commensals and host immune and endocrine cells. In this review, we highlight the importance of tryptophan-derived metabolites in host physiology, and summarize the recent findings on the role of tryptophan catabolites in preserving intestinal homeostasis and fine-tuning immune and metabolic responses. Furthermore, we discuss the latest evidence on the effects of microbial tryptophan catabolites, describe their mechanisms of action, and discuss how perturbations of microbial tryptophan metabolism may affect the course of intestinal and extraintestinal disorders, including inflammatory bowel diseases, metabolic disorders, chronic kidney diseases, and cardiovascular diseases.

The Gene Signature of Activated M-CSF-Primed Human Monocyte-Derived Macrophages Is IL-10-Dependent

During inflammatory responses, monocytes are recruited into inflamed tissues, where they become monocyte-derived macrophages and acquire pro-inflammatory and tissue-damaging effects in response to the surrounding environment. In fact, monocyte-derived macrophage subsets are major pathogenic cells in inflammatory pathologies. Strikingly, the transcriptome of pathogenic monocyte-derived macrophage subsets resembles the gene profile of macrophage colony-stimulating factor (M-CSF)-primed monocyte-derived human macrophages (M-MØ). As M-MØ display a characteristic cytokine profile after activation (IL10high TNFlow IL23low IL6low), we sought to determine the transcriptional signature of M-MØ upon exposure to pathogenic stimuli. Activation of M-MØ led to the acquisition of a distinctive transcriptional profile characterized by the induction of a group of genes (Gene set 1) highly expressed by pathogenic monocyte-derived macrophages in COVID-19 and whose presence in tumor-associated macrophages (TAM) correlates with the expression of macrophage-specific markers (CD163, SPI1) and IL10. Indeed, Gene set 1 expression was primarily dependent on ERK/p38 and STAT3 activation, and transcriptional analysis and neutralization experiments revealed that IL-10 is not only required for the expression of a subset of genes within Gene set 1 but also significantly contributes to the idiosyncratic gene signature of activated M-MØ. Our results indicate that activation of M-CSF-dependent monocyte-derived macrophages induces a distinctive gene expression profile, which is partially dependent on IL-10, and identifies a gene set potentially helpful for macrophage-centered therapeutic strategies.

The role of SOCS proteins in the development of virus- induced hepatocellular carcinoma

Background

Liver cancer has become one of the most common cancers and has a high mortality rate. Hepatocellular carcinoma is one of the most common liver cancers, and its occurrence and development process are associated with chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infections.

Main body

The serious consequences of chronic hepatitis virus infections are related to the viral invasion strategy. Furthermore, the viral escape mechanism has evolved during long-term struggles with the host. Studies have increasingly shown that suppressor of cytokine signaling (SOCS) proteins participate in the viral escape process. SOCS proteins play an important role in regulating cytokine signaling, particularly the Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway. Cytokines stimulate the expression of SOCS proteins, in turn, SOCS proteins inhibit cytokine signaling by blocking the JAK-STAT signaling pathway, thereby achieving homeostasis. By utilizing SOCS proteins, chronic hepatitis virus infection may destroy the host’s antiviral responses to achieve persistent infection.

Conclusions

This review provides recent knowledge regarding the role of SOCS proteins during chronic hepatitis virus infection and provides some new ideas for the future treatment of chronic hepatitis.

Kynurenine induces an age-related phenotype in bone marrow stromal cells

Advanced age is one of the important contributing factors for musculoskeletal deterioration. Although the exact mechanism behind this degeneration is unknown, it has been previously established that nutritional signaling plays a vital role in musculoskeletal pathophysiology. Our group established the vital role of the essential amino acid, tryptophan, in aging musculoskeletal health. With advanced age, inflammatory factors activate indoleamine 2,3-dioxygenase (IDO1) and accumulate excessive intermediate tryptophan metabolites such as Kynurenine (KYN). With age, Kynurenine accumulates and suppresses osteogenic differentiation, impairs autophagy, promotes early senescence, and alters cellular bioenergetics of bone marrow stem cells. Recent studies have shown that Kynurenine negatively impacts bone marrow stromal cells (BMSCs) and, consequently, promotes bone loss. Overall, understanding the mechanism behind BMSCs losing their ability for osteogenic differentiation can provide insight into the prevention of osteoporosis and the development of targeted therapies. Therefore, in this article, we review Kynurenine and how it plays a vital role in BMSC dysfunction and bone loss with age.

Suppressors of cytokine signaling (SOCS) proteins in inflammatory bone disorders

Suppressor of cytokine signaling (SOCS) proteins are significant regulators of cellular immune responses. Therefore, the role of SOCS in bone-inflammatory disorders, including arthritis and periodontitis, has been investigated in experimental and clinical conditions. Recent evidence shows that SOCS proteins are expressed in major bone-related cells, including osteoblasts, osteoclasts, chondrocytes and synoviocytes, although their direct role in these cells is not fully described. These signaling molecules, especially SOCS1, 2 and 3, were shown to play critical roles in the control of bone resorption associated to inflammation. This review focuses on the involvement of SOCS proteins in inflammatory bone remodeling, including their direct and indirect role in the control of osteoclast hyperactivation, during arthritis and periodontitis. The description of the roles of SOCS proteins in inflammatory bone diseases highlights the pathways involved in the pathophysiology of these conditions and, thus, may contribute to the development and improvement of potential therapeutic interventions.

Host-microbiome interactions: the aryl hydrocarbon receptor as a critical node in tryptophan metabolites to brain signaling

Tryptophan (Trp) is not only a nutrient enhancer but also has systemic effects. Trp metabolites signaling through the well-known aryl hydrocarbon receptor (AhR) constitute the interface of microbiome-gut-brain axis. However, the pathway through which Trp metabolites affect central nervous system (CNS) function have not been fully elucidated. AhR participates in a broad variety of physiological and pathological processes that also highly relevant to intestinal homeostasis and CNS diseases. Via the AhR-dependent mechanism, Trp metabolites connect bidirectional signaling between the gut microbiome and the brain, mediated via immune, metabolic, and neural (vagal) signaling mechanisms, with downstream effects on behavior and CNS function. These findings shed light on the complex Trp regulation of microbiome-gut-brain axis and add another facet to our understanding that dietary Trp is expected to be a promising noninvasive approach for alleviating systemic diseases.

Role of SOCS2 in the Regulation of Immune Response and Development of the Experimental Autoimmune Encephalomyelitis

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system (CNS). Experimental Autoimmune Encephalomyelitis (EAE) is the most widely used animal model for the study of MS. The Suppressor of Cytokine Signaling (SOCS) 2 protein plays a critical role in regulating the immune responses. The role of SOCS2 during EAE has not been explored. EAE was induced in WT and SOCS2^−/− mice using myelin oligodendrocyte glycoprotein (MOG_35-55) peptide. Brain and spinal cord were examined during the peak (day 14) and recovery phase (day 28) of the disease. SOCS2 was upregulated in the brain of WT mice at the peak and recovery phase of EAE. The development of the acute phase was slower in onset in SOCS2^−/− mice and was associated with reduced number of Th1 (CD3⁺CD4⁺IFN-γ⁺) cells in the spinal cord and brain. However, while in WT mice, maximal clinical EAE score was followed by a progressive recovery; the SOCS2^−/− mice were unable to recover from locomotor impairment that occurred during the acute phase. There was a prolonged inflammatory response (increased Th1 and decreased Th2 and T regulatory cells) in the late phase of EAE in the CNS of SOCS2^−/− mice. Transplantation of bone marrow cells from SOCS2^−/− into irradiated WT mice resulted in higher lethality at the early phase of EAE. Altogether, these results suggest that SOCS2 plays a dual role in the immune response during EAE. It is necessary for damage during the acute phase damage but plays a beneficial role in the recovery stage of the disease.

The aryl hydrocarbon receptor: an environmental sensor integrating immune responses in health and disease

The environment, diet, microbiota and body's metabolism shape complex biological processes in health and disease. However, our understanding of the molecular pathways involved in these processes is still limited. The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that integrates environmental, dietary, microbial and metabolic cues to control complex transcriptional programmes in a ligand-specific, cell-type-specific and context-specific manner. In this Review, we summarize our current knowledge of AHR and the transcriptional programmes it controls in the immune system. Finally, we discuss the role of AHR in autoimmune and neoplastic diseases of the central nervous system, with a special focus on the gut immune system, the gut-brain axis and the therapeutic potential of targeting AHR in neurological disorders.

KIAA0317 regulates pulmonary inflammation through SOCS2 degradation

Dysregulated proinflammatory cytokine release has been implicated in the pathogenesis of several life-threatening acute lung illnesses such as pneumonia, sepsis, and acute respiratory distress syndrome. Suppressors of cytokine signaling proteins, particularly SOCS2, have recently been described as antiinflammatory mediators. However, the regulation of SOCS2 protein has not been described. Here we describe a mechanism of SOCS2 regulation by the action of the ubiquitin E3 ligase KIAA0317. KIAA0317-mediated degradation of SOCS2 exacerbated inflammation in vitro, and depletion of KIAA0317 in vivo ameliorated pulmonary inflammation. KIAA0317-knockout mice exhibited resistance to LPS-induced pulmonary inflammation, while KIAA03017 reexpression mitigated this effect. We uncovered a small molecule inhibitor of KIAA0317 protein (BC-1365) that prevented SOCS2 degradation and attenuated LPS- and P. aeruginosa-induced lung inflammation in vivo. These studies show KIAA0317 to be a critical mediator of pulmonary inflammation through its degradation of SOCS2 and a potential candidate target for therapeutic inhibition.

MiRNA-155 Regulates the Th17/Treg Ratio by Targeting SOCS1 in Severe Acute Pancreatitis

Acute pancreatitis (AP) is a serious condition associated with intestinal barrier disruption or inflammation of the pancreatic tissue. Specific microRNAs are involved in the pathogenesis of AP, during which IL-17-producing CD4⁺ T helper (Th17) cells accumulate in the pancreas. In this study, significantly increased levels of miR-155 were detected in clinical samples from patients with AP, and overexpression of miR-155 correlated with severe AP (SAP). To identify the effect of miR-155 on T cell differentiation, we isolated CD4⁺ T lymphocytes and in vitro experiments showed that inhibition of miR-155 significantly reversed the stress-induced increase in the Th17/Treg ratio. The results also showed that miR-155 increased the Th17-mediated inflammatory response by targeting SOCS1. The interaction between miR-155 and the 3^′-UTR of SOCS1 was confirmed by a dual luciferase reporter assay and RT-PCR. Experimental AP of varying severity was induced in BALB/c mice by caerulein hyperstimulation and miR-155 expression was found to increase with disease progression. Inhibition of miR-155 expression significantly improved the pathology of the pancreas. We also observed downregulation of expression of inflammatory factors, IL-17, SOCS1 and phosphorylated STAT1 after miR-155 inhibition. In summary, miR-155 regulates the Th17/Treg ratio by targeting SOCS1, most probably via direct binding to its 3^′-UTR region, indicating that this microRNA may be a potential biomarker and/or therapeutic target for AP.

Tespa1 Deficiency Dampens Thymus-Dependent B-Cell Activation and Attenuates Collagen-Induced Arthritis in Mice

Thymocyte-expressed, positive selection-associated 1 (Tespa1) plays an important role in both T cell receptor (TCR)-driven thymocyte development and in the FcεRI-mediated activation of mast cells. Herein, we show that lack of Tespa1 does not impair B cell development but dampens the in vitro activation and proliferation of B cells induced by T cell-dependent (TD) antigens, significantly reduces serum antibody concentrations in vivo, and impairs germinal center formation in both aged and TD antigen-immunized mice. We also provide evidence that dysregulated signaling in Tespa1-deficient B cells may be linked to CD40-induced TRAF6 degradation, and subsequent effects on 1-phosphatidylinositol-4,5-bisphosphate phosphodiesterase gamma-2 (PLCγ2) phosphorylation, MAPK activation, and calcium influx. Furthermore, we demonstrate that Tespa1 plays a critical role in pathogenic B cells, since Tespa1-deficient chimeric mice showed a lower incidence and clinical disease severity of collagen-induced arthritis. Overall, our study demonstrates that Tespa1 is essential for TD B cell responses, and suggests an important role for Tespa1 during the development of autoimmune arthritis.

Inhibition of hypoxia-associated response and kynurenine production in response to hyperbaric oxygen as mechanisms involved in protection against experimental cerebral malaria

Cerebral malaria (CM) is a multifactorial syndrome involving an exacerbated proinflammatory status, endothelial cell activation, coagulopathy, hypoxia, and accumulation of leukocytes and parasites in the brain microvasculature. Despite significant improvements in malaria control, 15% of mortality is still observed in CM cases, and 25% of survivors develop neurologic sequelae for life-even after appropriate antimalarial therapy. A treatment that ameliorates CM clinical signs, resulting in complete healing, is urgently needed. Previously, we showed a hyperbaric oxygen (HBO)-protective effect against experimental CM. Here, we provide molecular evidence that HBO targets brain endothelial cells by decreasing their activation and inhibits parasite and leukocyte accumulation, thus improving cerebral microcirculatory blood flow. HBO treatment increased the expression of aryl hydrocarbon receptor over hypoxia-inducible factor 1-α (HIF-1α), an oxygen-sensitive cytosolic receptor, along with decreased indoleamine 2,3-dioxygenase 1 expression and kynurenine levels. Moreover, ablation of HIF-1α expression in endothelial cells in mice conferred protection against CM and improved survival. We propose that HBO should be pursued as an adjunctive therapy in CM patients to prolong survival and diminish deleterious proinflammatory reaction. Furthermore, our data support the use of HBO in therapeutic strategies to improve outcomes of non-CM disorders affecting the brain.-Bastos, M. F., Kayano, A. C. A. V., Silva-Filho, J. L., Dos-Santos, J. C. K., Judice, C., Blanco, Y. C., Shryock, N., Sercundes, M. K., Ortolan, L. S., Francelin, C., Leite, J. A., Oliveira, R., Elias, R. M., Câmara, N. O. S., Lopes, S. C. P., Albrecht, L., Farias, A. S., Vicente, C. P., Werneck, C. C., Giorgio, S., Verinaud, L., Epiphanio, S., Marinho, C. R. F., Lalwani, P., Amino, R., Aliberti, J., Costa, F. T. M. Inhibition of hypoxia-associated response and kynurenine production in response to hyperbaric oxygen as mechanisms involved in protection against experimental cerebral malaria.

TRAF molecules in inflammation and inflammatory diseases

Purpose of Review

This review presents an overview of the current knowledge of TRAF molecules in inflammation with an emphasis on available human evidence and direct in vivo evidence of mouse models that demonstrate the contribution of TRAF molecules in the pathogenesis of inflammatory diseases.

Recent Findings

The tumor necrosis factor receptor (TNF-R)-associated factor (TRAF) family of cytoplasmic proteins was initially identified as signaling adaptors that bind directly to the intracellular domains of receptors of the TNF-R superfamily. It is now appreciated that TRAF molecules are widely employed in signaling by a variety of adaptive and innate immune receptors as well as cytokine receptors. TRAF-dependent signaling pathways typically lead to the activation of nuclear factor-κBs (NF-κBs), mitogen-activated protein kinases (MAPKs), or interferon-regulatory factors (IRFs). Most of these signaling pathways have been linked to inflammation, and therefore TRAF molecules were expected to regulate inflammation and inflammatory responses since their discovery in 1990s. However, direct in vivo evidence of TRAFs in inflammation and especially in inflammatory diseases had been lacking for many years, partly due to the difficulty imposed by early lethality of TRAF2^-/-, TRAF3^-/-, and TRAF6^-/- mice. With the creation of conditional knockout and lineage-specific transgenic mice of different TRAF molecules, our understanding about TRAFs in inflammation and inflammatory responses has rapidly advanced during the past decade.

Summary

Increasing evidence indicates that TRAF molecules are versatile and indispensable regulators of inflammation and inflammatory responses and that aberrant expression or function of TRAFs contributes to the pathogenesis of inflammatory diseases.

What can Sjögren's syndrome-like disease in mice contribute to human Sjögren's syndrome?

For decades, Sjögren's syndrome (SS) and Sjögren's syndrome-like (SS-like) disease in patients and mouse models, respectively, have been intensely investigated in attempts to identify the underlying etiologies, the pathophysiological changes defining disease phenotypes, the nature of the autoimmune responses, and the propensity for developing B cell lymphomas. An emerging question is whether the generation of a multitude of mouse models and the data obtained from their studies is actually important to the understanding of the human disease and potential interventional therapies. In this brief report, we comment on how and why mouse models can stimulate interest in specific lines of research that apparently parallel aspects of human SS. Focusing on two mouse models, NOD and B6·Il14α, we present the possible relevance of mouse models to human SS, highlighting a few selected disease-associated biological processes that have baffled both SS and SS-like investigations for decades.

TRAF6 Mediates Suppression of Osteoclastogenesis and Prevention of Ovariectomy-Induced Bone Loss by a Novel Prenylflavonoid

Given the limitations of current therapeutic options for postmenopausal osteoporosis, there is a need for alternatives with minimal adverse effects. In this study, we evaluated the effects of icaritin (ICT), a natural prenylflavonoid, on osteoclastogenesis both in vitro and in an ovariectomized (OVX) rat model and investigated its underlying molecular mechanism(s) of action. ICT inhibited osteoclast formation in two osteoclast precursor models, RAW 264.7 mouse monocyte cell line and human PBMC. ICT also inhibited sealing zone and resorption pit formation in a dose-dependent manner. Mechanistically, ICT inhibited RANKL-induced NF-κB and MAPK/AP-1 pathways to suppress gene expression of nuclear factor of activated T cells (NFAT)c1, the master transcription regulator of osteoclast differentiation. ICT, by inhibiting the TRAF6/c-Src/PI3K pathway, suppressed NADPH oxidase-1 activation to attenuate intracellular ROS production and downregulate calcineurin phosphatase activity. As a result, NFATc1 nuclear translocation and activity was suppressed. Crucially, ICT promoted proteasomal degradation of TRAF6, the critical adaptor protein that transduces RANKL/RANK signaling, and the inhibitory effect of ICT on osteoclastogenesis was reversed by the proteasomal inhibitor MG 132. ICT administration inhibited OVX-induced bone loss and resorption by suppressing osteoclast formation and activity. Consistent with cellular studies, ICT downregulated TRAF6 and NFATc1 protein expression in CD11b⁺ /Gr-1^-/low osteoclast precursors isolated from OVX rats. Put together, we present novel findings that ICT, by downregulating TRAF6, coordinates inhibition of NF-κB, MAPK/AP-1, and ROS signaling pathways to reduce expression and activity of NFATc1. These results demonstrate the potential of ICT for treatment of postmenopausal osteoporosis and point to TRAF6 as a promising target for novel anti-osteoporotic drugs. © 2017 American Society for Bone and Mineral Research.

Tolerogenic nanoparticles inhibit T cell-mediated autoimmunity through SOCS2

Type 1 diabetes (T1D) is a T cell-dependent autoimmune disease that is characterized by the destruction of insulin-producing β cells in the pancreas. The administration to patients of ex vivo-differentiated FoxP3(+) regulatory T (Treg) cells or tolerogenic dendritic cells (DCs) that promote Treg cell differentiation is considered a potential therapy for T1D; however, cell-based therapies cannot be easily translated into clinical practice. We engineered nanoparticles (NPs) to deliver both a tolerogenic molecule, the aryl hydrocarbon receptor (AhR) ligand 2-(1'H-indole-3'-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE), and the β cell antigen proinsulin (NPITE+Ins) to induce a tolerogenic phenotype in DCs and promote Treg cell generation in vivo. NPITE+Ins administration to 8-week-old nonobese diabetic mice suppressed autoimmune diabetes. NPITE+Ins induced a tolerogenic phenotype in DCs, which was characterized by a decreased ability to activate inflammatory effector T cells and was concomitant with the increased differentiation of FoxP3(+) Treg cells. The induction of a tolerogenic phenotype in DCs by NPs was mediated by the AhR-dependent induction of Socs2, which resulted in inhibition of nuclear factor κB activation and proinflammatory cytokine production (properties of tolerogenic DCs). Together, these data suggest that NPs constitute a potential tool to reestablish tolerance in T1D and potentially other autoimmune disorders.

System-wide Analysis of the T Cell Response

The T cell receptor (TCR) controls the cellular adaptive immune response to antigens, but our understanding of TCR repertoire diversity and response to challenge is still incomplete. For example, TCR clones shared by different individuals with minimal alteration to germline gene sequences (public clones) are detectable in all vertebrates, but their significance is unknown. Although small in size, the zebrafish TCR repertoire is controlled by processes similar to those operating in mammals. Thus, we studied the zebrafish TCR repertoire and its response to stimulation with self and foreign antigens. We found that cross-reactive public TCRs dominate the T cell response, endowing a limited TCR repertoire with the ability to cope with diverse antigenic challenges. These features of vertebrate public TCRs might provide a mechanism for the rapid generation of protective T cell immunity, allowing a short temporal window for the development of more specific private T cell responses.

Immunity and Tolerance Induced by Intestinal Mucosal Dendritic Cells

Dendritic cells present in the digestive tract are constantly exposed to environmental antigens, commensal flora, and invading pathogens. Under steady-state conditions, these cells have high tolerogenic potential, triggering differentiation of regulatory T cells to protect the host from unwanted proinflammatory immune responses to innocuous antigens or commensals. On the other hand, these cells must discriminate between commensal flora and invading pathogens and mount powerful immune response against pathogens. A potential result of unbalanced tolerogenic versus proinflammatory responses mediated by dendritic cells is associated with chronic inflammatory conditions, such as Crohn's disease, ulcerative colitis, food allergies, and celiac disease. Herein, we review the dendritic cell population involved in mediating tolerance and immunity in mucosal surfaces, the progress in unveiling their development in vivo, and factors that can influence their functions.

Schizandrin A Inhibits Microglia-Mediated Neuroninflammation through Inhibiting TRAF6-NF-κB and Jak2-Stat3 Signaling Pathways

Microglial-mediated neuroinflammation has been established as playing a vital role in pathogenesis of neurodegenerative disorders. Thus, rational regulation of microglia functions to inhibit inflammation injury may be a logical and promising approach to neurodegenerative disease therapy. The purposes of the present study were to explore the neuroprotective effects and potential molecular mechanism of Schizandrin A (Sch A), a lignin compound isolated from Schisandra chinesnesis. Our observations showed that Sch A could significantly down-regulate the increased production of nitric oxide (NO), tumor necrosis factor (TNF)-α and interleukin (IL)-6 induced by lipopolysaccharide (LPS) both in BV-2 cells and primary microglia cells. Moreover, Sch A exerted obvious neuroprotective effects against inflammatory injury in neurons when exposed to microglia-conditioned medium. Investigations of the mechanism showed the anti-inflammatory effect of Sch A involved the inhibition of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) expression levels and inhibition of the LPS-induced TRAF6-IKKβ-NF-κB pathway. Furthermore, inhibition of Jak2-Stat3 pathway activation and Stat3 nuclear translocation also was observed. In conclusion, SchA can exert anti-inflammatory and neuroprotective effects by alleviating microglia-mediated neuroinflammation injury through inhibiting the TRAF6-IKKβ-NF-κB and Jak2-Stat3 signaling pathways.

The mannose receptor negatively modulates the Toll-like receptor 4-aryl hydrocarbon receptor-indoleamine 2,3-dioxygenase axis in dendritic cells affecting T helper cell polarization

BACKGROUND

Dendritic cells (DCs) are key players in the induction and re-elicitation of TH2 responses to allergens. We have previously shown that different C-type lectin receptors on DCs play a major role in allergen recognition and uptake. In particular, mannose receptor (MR), through modulation of Toll-like receptor (TLR) 4 signaling, can regulate indoleamine 2,3-dioxygenase (IDO) activity, favoring TH2 responses. Interestingly, the aryl hydrocarbon receptor (AhR), a ligand-dependent transcription factor with an emerging role in immune modulation, has been implicated in IDO activation in response to TLR stimulation.

OBJECTIVE

Here we investigated how allergens and lectins modulate the TLR4-AhR-IDO axis in human monocyte-derived DCs.

METHODS

Using a combination of genomics, proteomics, and immunologic studies, we investigated the role of MR and AhR in IDO regulation and its effect on T helper cell differentiation.

RESULTS

We have demonstrated that LPS induces both IDO isoforms (IDO1 and IDO2) in DCs, with partial involvement of AhR. Additionally, we found that, like mannan, different airborne allergens can effectively downregulate TLR4-induced IDO1 and IDO2 expression, most likely through binding to the MR. Mannose-based ligands were also able to downregulate IL-12p70 production by DCs, affecting T helper cell polarization. Interestingly, AhR and some components of the noncanonical nuclear factor κB pathway were shown to be downregulated after MR engagement, which could explain the regulatory effects of MR on IDO expression.

CONCLUSION

Our work demonstrates a key role for MR in the modulation of the TLR4-AhR-IDO axis, which has a significant effect on DC behavior and the development of immune responses against allergens.

Socs1 and Socs3 degrades Traf6 via polyubiquitination in LPS-induced acute necrotizing pancreatitis

Mechanisms involved in inflammatory development during acute pancreatitis (AP) are largely vague, especially in the transformation of acute edematous pancreatitis (AEP) into acute necrotizing pancreatitis (ANP). This current study aims to investigate the functions of Traf6 in different AP models in vitro and in vivo, and to identify the possible regulatory mechanism in the progression of inflammation from mild to severe. Our data revealed that the level of Traf6 expression was significantly increased in the mild AP induced by caerulein, and the upregulation of Traf6 played a protective role in acinar cells against caerulein-induced apoptosis. In contrast, only Traf6 protein but not mRNA was downregulated in the severe ANP induced by combination treatment of caerulein and LPS. Mechanistic studies showed that LPS upregulated the levels of Socs1 and Socs3 expressions in acinar cells, Socs1 and Socs3 interacted Traf6 directly and degraded Traf6 protein via polyubiquitination, thereby counteracted the protective function of Traf6. In vivo study further showed that combination treatment of caerulein and LPS failed to induce an ANP model in the TLR4 knockout mice, and the level of Traf6 expression in the pancreatic tissues remained the same as that from the acute edematous pancreatitis (AEP) mouse. Taken together, our study reveals that Traf6 functioned as a protective factor in the progression of AP, and LPS-induced Socs1 and Socs3 exacerbate mild AP to severe AP, which provides evidence for developing a new therapeutic target to combat AP.

Possible role of TLR4 and TLR9 SNPs in protection against congenital toxoplasmosis

The purpose of this investigation was the determination of the distribution of genotypes at single nucleotide polymorphisms (SNPs) of the toll-like receptor 4 (TLR4) and the toll-like receptor 9 (TLR9) in fetuses and newborns congenitally infected with Toxoplasma gondii and the identification of genetic changes predisposing to infection development. The study involved 20 fetuses and newborns with congenital toxoplasmosis and 50 uninfected controls. The levels of IgG and IgM antibodies against T. gondii, as well as IgG avidity, were estimated by enzyme-linked fluorescent assay (ELFA) tests. T. gondii DNA loads in amniotic fluids were assayed by the real-time (RT) quantitative polymerase chain reaction (Q PCR) technique for parasitic B1 gene. TLR4 and TLR9 SNPs were identified using a self-designed multiplex nested PCR-restriction fragment length polymorphism (RFLP) assay. Randomly selected genotypes at SNPs were confirmed by sequencing. All the genotypes were tested for Hardy–Weinberg equilibrium and TLR4 genotypes were analyzed for linkage disequilibrium. A correlation was studied between the genotypes or haplotypes and the development of congenital toxoplasmosis using a logistic regression model. Single SNP analysis showed no statistically significant differences in the distribution of distinct genotypes at the analyzed TLR4 and TLR9 SNPs between T. gondii-infected fetuses and newborns and the controls. Taking into account the prevalence of alleles residing within polymorphic sites, similar prevalence rates were observed in both of the studied groups. The multiple SNP analysis indicated GTG variants at the TLR4 and TLR9 SNPs to be significantly less frequent in offspring with congenital toxoplasmosis than in uninfected offspring (p ≤ 0.0001). TLR4 and TLR9 SNPs seem to be involved in protection against congenital toxoplasmosis.

Lipoxin A4 inhibits lipopolysaccharide-induced production of inflammatory cytokines in keratinocytes by up-regulating SOCS2 and down-regulating TRAF6

Liopxin A4 (LXA4) is considered to be a crucial modulator in the inflammatory responses. In the present study, we aimed to study the effect of LXA4 on the inflammatory cytokines production induced by lipopolysaccharide (LPS) and the possible mechanism in normal human epidermal keratinocytes (NHEKs). NHEKs were isolated and cultured. The expression of toll-like receptor 4 (TLR4), LXA4 receptor (ALXR) and aryl hydrocarbon receptor (AhR) in NHEKs was detected by reverse transcription polymerase chain reaction (RT-PCR). The mRNA and protein levels of tumor necrosis factor-alpha (TNF-α) and interleukin-1β (IL-1β) were determined in NHEKs stimulated by LPS (10 μg/mL) with or without preincubation with LXA4 (100 nmol/L) for 30 min by real-time quantitative PCR (real-time qPCR) and enzyme-linked immunosorbent assay (ELISA), respectively. The expression levels of tumor necrosis factor receptor-associated factor 6 (TRAF6) and suppressors of cytokine signaling 2 (SOCS2) mRNAs and proteins, and nuclear translocation of NF-kB-p65 were measured by real-time qPCR and Western blotting, respectively. The results showed that NHEKs expressed TLR4, ALXR and AhR. LXA4 significantly inhibited the mRNA and protein expression levels of TNF-α, IL-1β and TRAF6 induced by LPS in NHEKs, and LXA4 obviously increased the expression of SOCS2 at mRNA and protein levels. The nuclear NF-kB-p65 protein expression induced by LPS was inhibited after preincubation with LXA4 in NHEKs. It was concluded that LXA4 inhibits the LPS-induced production of TNF-α and IL-1β in NHEKs by up-regulating SOCS2 and down-regulating TRAF6.

AhR-Mediated, Non-Genomic Modulation of IDO1 Function

The evolutionary process has conferred a dual – enzymatic and signaling – function on the ancestral metabolic enzyme indoleamine 2,3-dioxygenase 1 (IDO1), which has long been known for converting the essential amino acid tryptophan (TRP) into neuroactive and immunoactive catabolites (kynurenines). In addition to TRP catabolic activity, phosphorylated immunoreceptor tyrosine-based inhibitory motifs, present in the IDO1 protein, act as docking sites for different molecular partners, which activate positive (transcriptional) or negative (post-translational) modulation of IDO1 protein. The ligand-operated transcription factor aryl hydrocarbon receptor (AhR) contributes to Ido1 transcription, and it can be operated by both exogenous and endogenous ligands, including l-kynurenine itself, the first byproduct of TRP catabolism. Ligand-bound AhR is also a component of a ubiquitin ligase complex responsible for regulatory proteolysis of different target proteins. Because IDO1 half-life is controlled by the ubiquitin–proteasome system, we here discuss the possibility that AhR, in addition to enhancing Ido1 transcription, contributes to IDO1 regulation by a non-genomic mechanism affecting the protein’s half-life.

Alterations in gene array patterns in dendritic cells from aged humans

Dendritic cells (DCs) are major antigen-presenting cells that play a key role in initiating and regulating innate and adaptive immune responses. DCs are critical mediators of tolerance and immunity. The functional properties of DCs decline with age. The purpose of this study was to define the age-associated molecular changes in DCs by gene array analysis using Affymatrix GeneChips. The expression levels of a total of 260 genes (1.8%) were significantly different (144 down-regulated and 116 upregulated) in monocyte-derived DCs (MoDCs) from aged compared to young human donors. Of the 260 differentially expressed genes, 24% were down-regulated by more than 3-fold, suggesting that a large reduction in expression occurred for a notable number of genes in the aged. Our results suggest that the genes involved in immune response to pathogens, cell migration and T cell priming display significant age-related changes. Furthermore, downregulated genes involved in cell cycle arrest and DNA replication may play a critical role in aging-associated genetic instability. These changes in gene expression provide molecular based evidence for age-associated functional abnormalities in human DCs that may be responsible for the defects in adaptive immunity observed in the elderly.

A novel role of suppressor of cytokine signaling-2 in the regulation of TrkA neurotrophin receptor biology

Suppressor of cytokine signaling-2 (SOCS2) is a regulator of intracellular responses to growth factors and cytokines. Cultured dorsal root ganglia neurons from neonatal mice with increased or decreased SOCS2 expression were examined for altered responsiveness to nerve growth factor (NGF). In the presence of NGF, SOCS2 over-expression increased neurite length and complexity, whereas loss of SOCS2 reduced neurite outgrowth. Neither loss nor gain of SOCS2 expression altered the relative survival of these cells, suggesting that SOCS2 can discriminate between the differentiation and survival responses to NGF. Interaction studies in 293T cells revealed that SOCS2 immunoprecipitates with TrkA and a juxtamembrane motif of TrkA was required for this interaction. SOCS2 also immunoprecipitated with endogenous TrkA in PC12 Tet-On cells. Over-expression of SOCS2 in PC12 Tet-On cells increased total and surface TrkA expression. In contrast, dorsal root ganglion neurons which over-expressed SOCS2 did not exhibit significant changes in total levels but an increase in surface TrkA was noted. SOCS2-induced neurite outgrowth in PC12 Tet-On cells correlated with increased and prolonged activation of pAKT and pErk1/2 and required an intact SOCS2 SH2 domain and SOCS box domain. This study highlights a novel role for SOCS2 in the regulation of TrkA signaling and biology.

Toward understanding the role of aryl hydrocarbon receptor in the immune system: current progress and future trends

The immune system is regulated by distinct signaling pathways that control the development and function of the immune cells. Accumulating evidence suggest that ligation of aryl hydrocarbon receptor (Ahr), an environmentally responsive transcription factor, results in multiple cross talks that are capable of modulating these pathways and their downstream responsive genes. Most of the immune cells respond to such modulation, and many inflammatory response-related genes contain multiple xenobiotic-responsive elements (XREs) boxes upstream. Active research efforts have investigated the physiological role of Ahr in inflammation and autoimmunity using different animal models. Recently formed paradigm has shown that activation of Ahr by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or 3,3′-diindolylmethane (DIM) prompts the differentiation of CD4⁺Foxp3⁺ regulatory T cells (Tregs) and inhibits T helper (Th)-17 suggesting that Ahr is an innovative therapeutic strategy for autoimmune inflammation. These promising findings generate a basis for future clinical practices in humans. This review addresses the current knowledge on the role of Ahr in different immune cell compartments, with a particular focus on inflammation and autoimmunity.

TRAF molecules in cell signaling and in human diseases

The tumor necrosis factor receptor (TNF-R)-associated factor (TRAF) family of intracellular proteins were originally identified as signaling adaptors that bind directly to the cytoplasmic regions of receptors of the TNF-R superfamily. The past decade has witnessed rapid expansion of receptor families identified to employ TRAFs for signaling. These include Toll-like receptors (TLRs), NOD-like receptors (NLRs), RIG-I-like receptors (RLRs), T cell receptor, IL-1 receptor family, IL-17 receptors, IFN receptors and TGFβ receptors. In addition to their role as adaptor proteins, most TRAFs also act as E3 ubiquitin ligases to activate downstream signaling events. TRAF-dependent signaling pathways typically lead to the activation of nuclear factor-κBs (NF-κBs), mitogen-activated protein kinases (MAPKs), or interferon-regulatory factors (IRFs). Compelling evidence obtained from germ-line and cell-specific TRAF-deficient mice demonstrates that each TRAF plays indispensable and non-redundant physiological roles, regulating innate and adaptive immunity, embryonic development, tissue homeostasis, stress response, and bone metabolism. Notably, mounting evidence implicates TRAFs in the pathogenesis of human diseases such as cancers and autoimmune diseases, which has sparked new appreciation and interest in TRAF research. This review presents an overview of the current knowledge of TRAFs, with an emphasis on recent findings concerning TRAF molecules in signaling and in human diseases.

Identification of cytokinin-responsive genes using microarray meta-analysis and RNA-Seq in Arabidopsis

Cytokinins are N(6)-substituted adenine derivatives that play diverse roles in plant growth and development. We sought to define a robust set of genes regulated by cytokinin as well as to query the response of genes not represented on microarrays. To this end, we performed a meta-analysis of microarray data from a variety of cytokinin-treated samples and used RNA-seq to examine cytokinin-regulated gene expression in Arabidopsis (Arabidopsis thaliana). Microarray meta-analysis using 13 microarray experiments combined with empirically defined filtering criteria identified a set of 226 genes differentially regulated by cytokinin, a subset of which has previously been validated by other methods. RNA-seq validated about 73% of the up-regulated genes identified by this meta-analysis. In silico promoter analysis indicated an overrepresentation of type-B Arabidopsis response regulator binding elements, consistent with the role of type-B Arabidopsis response regulators as primary mediators of cytokinin-responsive gene expression. RNA-seq analysis identified 73 cytokinin-regulated genes that were not represented on the ATH1 microarray. Representative genes were verified using quantitative reverse transcription-polymerase chain reaction and NanoString analysis. Analysis of the genes identified reveals a substantial effect of cytokinin on genes encoding proteins involved in secondary metabolism, particularly those acting in flavonoid and phenylpropanoid biosynthesis, as well as in the regulation of redox state of the cell, particularly a set of glutaredoxin genes. Novel splicing events were found in members of some gene families that are known to play a role in cytokinin signaling or metabolism. The genes identified in this analysis represent a robust set of cytokinin-responsive genes that are useful in the analysis of cytokinin function in plants.

Lipoxin A₄ and 15-epi-lipoxin A₄ protect against experimental cerebral malaria by inhibiting IL-12/IFN-γ in the brain

Cerebral malaria is caused by infection with Plasmodium falciparum and can lead to severe neurological manifestations and predominantly affects sub-Saharan African children. The pathogenesis of this disease involves unbalanced over-production of pro-inflammatory cytokines. It is clear that signaling though IL-12 receptor is a critical step for development of cerebral malaria, IL-12 genetic deficiency failed to show the same effect, suggesting that there is redundancy among the soluble mediators which leads to immunopathology and death. Consequently, counter-regulatory mediators might protect the host during cerebral malaria. We have previously showed that endogenously produced lipoxins, which are anti-inflammatory mediators generated by 5-lipoxygenase (5-LO)-dependent metabolism of arachidonic acid, limit host damage in a model of mouse toxoplasmosis. We postulated here that lipoxins might also play a counter-regulatory role during cerebral malaria. To test this hypothesis, we infected 5-LO-deficient hosts with P. berghei ANKA strain, which induces a mouse model of cerebral malaria (ECM). Our results show accelerated mortality concomitant with exuberant IL-12 and IFN-γ production in the absence of 5-lipoxygenase. Moreover, in vivo administration of lipoxin to 5-LO-deficient hosts prevented early mortality and reduced the accumulation of CD8⁺IFN-γ⁺ cells in the brain. Surprisingly, WT animals treated with lipoxin either at the time of infection or 3 days post-inoculum also showed prolonged survival and diminished brain inflammation, indicating that although protective, endogenous lipoxin production is not sufficient to optimally protect the host from brain damage in cerebral malaria. These observations establish 5-LO/LXA₄ as a host protective pathway and suggest a new therapeutic approach against human cerebral malaria (HCM). (255 words).

Suppressor of cytokine signaling 2 (SOCS2) associates with FLT3 and negatively regulates downstream signaling

The suppressor of cytokine signaling 2 (SOCS2) is a member of the SOCS family of E3 ubiquitin ligases. SOCS2 is known to regulate signal transduction by cytokine receptors and receptor tyrosine kinases. The receptor tyrosine kinase FLT3 is of importance for proliferation, survival and differentiation of hematopoietic cells and is frequently mutated in acute myeloid leukemia. We observed that SOCS2 associates with activated FLT3 through phosphotyrosine residues 589 and 919, and co-localizes with FLT3 in the cell membrane. SOCS2 increases FLT3 ubiquitination and accelerates receptor degradation in proteasomes. SOCS2 negatively regulates FLT3 signaling by blocking activation of Erk 1/2 and STAT5. Furthermore, SOCS2 expression leads to a decrease in FLT3-ITD-mediated cell proliferation and colony formation. Thus, we suggest that SOCS2 associates with activated FLT3 and negatively regulates the FLT3 signaling pathways.

SNPs in toll-like receptor (TLR) genes as new genetic alterations associated with congenital toxoplasmosis?

Nearly 40 % of pregnant women are infected with Toxoplasma gondii. Primary infections in pregnant women result, in approximately 30–50 % of patients, in transmission of T. gondii through the placenta to the fetus and then in congenital infections with severe, sometimes fatal course. Studies still do not provide sufficient data on the genetic bases of the immunity in fetuses, newborns, and infants with congenital toxoplasmosis. Previous research showed the contribution of toll-like receptors (TLRs) to non-specific immunity against T. gondii invasion, observed in T. gondii-infected animals, especially mice. So far, the activity of TLRs in defense against T. gondii infections was observed particularly for TLR2, TLR4, and TLR9 molecules. Differential TLR activity associates with both cell types, including a variety of placental cells and stage of pregnancy. Several single-nucleotide polymorphisms (SNPs) residing in three genes encoding these receptors were reported as significant genetic modifications of TLRs associated with different pregnancy disorders. Despite those data, genetic alterations of TLRs which have contributed to innate immune response against T. gondii infections are still not precisely described. In this article, we present reasons for the research of the plausible role of SNPs residing in TLR2, TLR4, and TLR9 genes in congenital toxoplasmosis development.