Can Toll-Like Receptor (TLR) 2 be considered as a new target for immunotherapy against hepatitis B infection?

Retinoic acid-inducible gene 1 (RIG-1) and IFN-β promoter stimulator-1 (IPS-1) significantly down-regulated in the severe coronavirus disease 2019 (COVID-19)

INTRODUCTION

Retinoic acid-inducible gene 1 (RIG-1) and melanoma differentiation-associated protein 5 (MDA5) are the well-known cytoplasmic sensors that recognize microbial DNA or RNA and active down-stream molecules, including IFN-β promoter stimulator-1 (IPS-1) and receptor interacting protein 1 (RIP1). The roles played by the networked molecules on the infection with SARS-CoV-2 needs more investigations.

MATERIAL AND METHOD

In this project MDA5, RIG-1, IPS-1 and RIP1 mRNA levels were evaluated in 45 hospitalized patients suffering from coronavirus disease of 2019 (COVID-19) and 45 healthy subjects using Real Time-qPCR technique.

RESULT

The results showed significant decreased RIG-1 and IPS-1 in the SARS-CoV-2 infected patients when compared to healthy cases. MDA5 and RIP1 did not change when compared two groups. Male patients had similar expression of MDA5, RIG-1, IPS-1 and RIP1 when compared to female patients.

CONCLUSION

Based on the results, it seems that RIG-1 and its signaling molecule, IPS-1, play key roles in the peripheral blood immune cells against SARS-CoV-2 and, their down-regulation may be induced by the virus to escape from immune responses.

Novel Molecular Therapeutics Targeting Signaling Pathway to Control Hepatitis B Viral Infection

Numerous canonical cellular signaling pathways modulate hepatitis B virus (HBV) replication. HBV genome products are known to play a significant role in regulating these cellular pathways for the liver’s viral-related pathology and physiology and have been identified as the main factor in hepatocarcinogenesis. Signaling changes during viral replication ultimately affect cellular persistence, multiplication, migration, genome instability, and genome damage, leading to proliferation, evasion of apoptosis, block of differentiation, and immortality. Recent studies have documented that numerous signaling pathway agonists or inhibitors play an important role in reducing HBV replication in vitro and in vivo, and some have been used in phase I or phase II clinical trials. These optional agents as molecular therapeutics target cellular pathways that could limit the replication and transcription of HBV or inhibit the secretion of the small surface antigen of HBV in a signaling-independent manner. As principle-based available information, a combined strategy including antiviral therapy and immunomodulation will be needed to control HBV infection effectively. In this review, we summarize recent findings on interventions of molecular regulators in viral replication and the interactions of HBV proteins with the components of the various targeting cellular pathways, which may assist in designing novel agents to modulate signaling pathways to prevent HBV replication or carcinogenesis.

TLR2, as a Pathogen Recognition Receptor, Plays Critical Roles in Hepatitis B Outcome

The immune system of active and inactive chronic hepatitis B, as prolonged forms of hepatitis B, is unable to eradicate hepatitis B virus (HBV) from the infected hepatocytes completely. Toll-like receptors (TLRs) play key roles in the viral recognition and promotion of appropriate immune responses. The molecules also participate in the alteration of the target cell functions and transformation. TLR2 is the unique molecule that makes either homodimer or heterodimer with TLR1 and 6 and shows variable roles against viral infections. Therefore, it has been hypothesized that TLR2 may participate in both immune response against HBV and induction of the virus-related hepatic complications. The studies confirm the hypothesis and revealed that TLR2 is not only one of the main molecules altering the course of HBV infection, but also plays key roles in induction of hepatocellular carcinoma (HCC) and liver cirrhosis. However, recent studies demonstrated that the molecule can fight against HCC and liver cirrhosis. Collectively, it appears that nutrition habits, TLR2 gene polymorphisms, gut microbiome, HBV antigens, and activation of other receptors may play key roles in the determination of TLR2 functions.

Differential Expression of the TLR4 Gene in Pan-Cancer and Its Related Mechanism

Previous studies have revealed the relationship between toll-like receptor 4 (TLR4) polymorphisms and cancer susceptibility. However, the relationship between TLR4 and prognosis and immune cell infiltration in pan-cancer patients is still unclear. Through the Genotype-Tissue Expression (GTEx) and The Cancer Genome Atlas (TCGA) databases, the distinct expression of the TLR4 gene in 24 tumors and normal tissues was analyzed. Univariate Cox proportional hazards regression analysis was used to identify the cancer types whose TLR4 gene expression was related to prognosis. The relationship between TLR4 and tumor cell immune invasion was studied. Spearman's rank correlation coefficient was used to analyze the relationship among TLR4 and immune neoantigens, tumor mutation burden (TMB), microsatellite instability (MSI), DNA repair genes, and DNA methylation. Gene Set Enrichment Analysis (GSEA) was used to identify the tumor-related pathways that the TLR4 gene was highly expressed in; the expression of the TLR4 gene was verified with the Human Protein Atlas (HPA) database. Low expression of TLR4 was associated with an inferior prognosis in kidney renal clear cell carcinoma (KIRC), skin cutaneous melanoma (SKCM), and uterine corpus endometrial carcinoma (UCEC), while high expression was related to a poor prognosis in head and neck squamous cell carcinoma (HNSC), prostate adenocarcinoma (PRAD), stomach adenocarcinoma (STAD), and testicular germ cell tumor (TGCT). The expression of TLR4 was negatively correlated with the expression of B cells in STAD. The expression of TLR4 was positively correlated with the infiltration of B cells, CD4 and CD8 T cells, neutrophils, macrophages, and dendritic cells in STAD, KIRC, UCEC, TGCT, and SKCM. The expression of the TLR4 gene in KIRC, SKCM, STAD, TGCT, and UCEC was highly correlated with inducible T-cell costimulator (ICOS), cytotoxic T lymphocyte-associated molecule 4 (CTLA4), and CD28 immune checkpoints. Spearman's rank correlation coefficient showed that the expression of TLR4 gene was significantly correlated with TMB in STAD and UCEC and was prominently correlated with MSI in TGCT, STAD, and SKCM. The expression of the TLR4 gene was highly correlated with MLH1, MSH2, and MSH6 in KIRC, SKCM, and STAD. The expression of the TLR4 gene was remarkably correlated with the methyltransferases DNA methyltransferase 2 (DNMT2) and DNA methyltransferase 3-beta (DNMT3B) in SKCM and STAD. Enrichment analysis showed that TLR4 was highly expressed in the chemokine signaling pathway and the cell adhesion molecule and cytokine receptor interaction pathway. In summary, the expression of TLR4 is linked to the prognosis of KIRC, SKCM, STAD, TGCT, and UCEC patients and the level of immune infiltration of CD4, CD8 T cells, macrophages, neutrophils, and dendritic cells.

Up-regulation of AIM2 and TLR4 and down-regulation of NLRC4 are associated with septicemia

PURPOSE

Innate immunity receptors play key roles in recognition of bacterial associated molecular patterns. Inflammasomes and toll like receptors (TLRs) are the important innate immunity receptors. In this project transcription levels of TLR4, a TLR member, absent in melanoma 2 (AIM2) and NLR family CARD domain-containing protein 4 (NLRC4), as inflammasomes, in the patients suffering from septicemia.

METHODS

AIM2, NLRC4 and TLR4 mRNA levels were evaluated in the 40 patients suffering from septicemia and 40 healthy controls using Real-Time PCR technique.

RESULTS

Data analysis revealed that, although NLRC4 expression decreased, TLR4 and AIM2 levels significantly increased in the patients suffering from septicemia. Gender and infection with various bacteria did not affect expression of AIM2, NLRC4 and TLR4.

CONCLUSIONS

It appears that septicemia can be limited by immune responses in AIM2 and TLR4 dependent manner. The potential roles played by bacteria to down-regulation of NLRC4 need to be evaluated by further investigations.

Ionizing radiation and toll like receptors: A systematic review article

Ionizing radiation, including X and gamma rays, are used for various purposes such as; medicine, nuclear power, research, manufacturing, food preservation and construction. Furthermore, people are also exposed to ionizing radiation from their workplace or the environment. Apart from DNA fragmentation resulting in apoptosis, several additional mechanisms have been proposed to describe how radiation can alter human cell functions. Ionizing radiation may alter immune responses, which are the main cause of human disorders. Toll like receptors (TLRs) are important human innate immunity receptors which participate in several immune and non-immune cell functions including, induction of appropriate immune responses and immune related disorders. Based on the role played by ionizing radiation on human cell systems, it has been hypothesized that radiation may affect immune responses. Therefore, the main aim of this review article is to discuss recent information regarding the effects of ionizing radiation on TLRs and their related disorders.

Crosstalk network among multiple inflammatory mediators in liver fibrosis

Liver fibrosis is the common pathological basis of all chronic liver diseases, and is the necessary stage for the progression of chronic liver disease to cirrhosis. As one of pathogenic factors, inflammation plays a predominant role in liver fibrosis via communication and interaction between inflammatory cells, cytokines, and the related signaling pathways. Damaged hepatocytes induce an increase in pro-inflammatory factors, thereby inducing the development of inflammation. In addition, it has been reported that inflammatory response related signaling pathway is the main signal transduction pathway for the development of liver fibrosis. The crosstalk regulatory network leads to hepatic stellate cell activation and proinflammatory cytokine production, which in turn initiate the fibrotic response. Compared with the past, the research on the pathogenesis of liver fibrosis has been greatly developed. However, the liver fibrosis mechanism is complex and many pathways involved need to be further studied. This review mainly focuses on the crosstalk regulatory network among inflammatory cells, cytokines, and the related signaling pathways in the pathogenesis of chronic inflammatory liver diseases. Moreover, we also summarize the recent studies on the mechanisms underlying liver fibrosis and clinical efforts on the targeted therapies against the fibrotic response.

Up-regulation of RIP1 and IPS-1 in chronic HBV infected patients

IPS-1 and RIP1 are the main downstream molecules of RIG1 and MDA5, as intracytoplasmic receptors, which are the main receptors involved in recognition of internal and external viral double-stranded RNA. In this project, mRNA levels of IPS-1 and RIP1 were investigated in the peripheral blood immune cells of chronic hepatitis B (CHB) patients. IPS-1 and RIP1 mRNA levels were measured in 60 CHB patients and 120 healthy subjects, using RT-qPCR technique. A significant increase in expression levels of IPS-1 and RIP1 was found in patients when compared to healthy individuals. There was no correlation between IPS-1 and RIP1expression levels with the serum levels of hepatitis B e-Antigen (HBeAg) and liver enzymes in patients. Based on the results, it seems that IPS-1 and RIP1 can participate in the induction of low chronic inflammation, which is a main cause of liver cirrhosis and hepatocellular carcinoma.

Hepatitis B Virus-Induced Imbalance of Inflammatory and Antiviral Signaling by Differential Phosphorylation of STAT1 in Human Monocytes

It is not clear how hepatitis B virus (HBV) modulates host immunity during chronic infection. In addition to the key mediators of inflammatory response in viral infection, monocytes also express a high-level IFN-stimulated gene, CH25H, upon response to IFN-α exerting an antiviral effect. In this study, the mechanism by which HBV manipulates IFN signaling in human monocytes was investigated. We observed that monocytes from chronic hepatitis B patients express lower levels of IFN signaling/stimulated genes and higher levels of inflammatory cytokines compared with healthy donors. HBV induces monocyte production of inflammatory cytokines via TLR2/MyD88/NF-κB signaling and STAT1-Ser727 phosphorylation and inhibits IFN-α-induced stat1, stat2, and ch25h expression through the inhibition of STAT1-Tyr701 phosphorylation and in an IL-10-dependent, partially autocrine manner. Further, we found that enhancement of STAT1 activity with a small molecule (2-NP) rescued HBV-mediated inhibition of IFN signaling and counteracted the induction of inflammatory cytokines. In conclusion, HBV contributes to the monocyte inflammatory response but inhibits their IFN-α/β responsiveness to impair antiviral innate immunity. These effects are mediated via differential phosphorylation of Tyr701 and Ser727 of STAT1.

Inflammasomes and their roles in the pathogenesis of viral hepatitis and their related complications: An updated systematic review

Inflammasomes are a set of innate receptors which are the responsible molecules for activation of pro-interleukin (IL)-1β and IL-18 and induction of inflammation. Due to the key roles of the inflammasomes in the induction of inflammation, it has been hypothesized that the molecules may be the main parts of immune responses against viral infections and the tissue damage. Because some cases of viral hepatitis infections, including hepatitis B and C, are diagnosed as chronic and may be associated with various complications such as liver cirrhosis and hepatocellular carcinoma (HCC), several studies focused on the roles played by the inflammation on the pathogenesis of viral hepatitis. Based on the roles played by inflammasomes in induction of inflammation, it has been hypothesized that inflammasomes may be the main parts of the puzzle of the viral hepatitis complications. This article reviews the roles of the inflammasomes in the pathogenesis of hepatitis B and C viral infections and their complications, liver cirrhosis, and HCC.

Toll-like receptor 4 and breast cancer: an updated systematic review

Toll-like receptors (TLRs) may play dual roles in human cancers. TLR4 is a key molecule which may participate in both friend and foe roles against breast cancer. This review article collected recent data regarding the mechanisms used by TLR4 in the eradication of breast cancer cells and induction of the tumor cells, and discussed the mechanisms involved in the various functions of TLR4. The literature searches revealed that TLR4 is a key molecule that participates in breast cancer cell eradication or induction of breast cancer development and also transformation of the normal cells. TLR4 eradicates breast cancer cells via recognition of their DAMPs and then induces immune responses. Over-expression of TLR4 and also alterations in its signaling, including association of some intrinsic pathways such as TGF-β signaling and TP53, are the crucial factors to alter TLR4 functions against breast cancer.

Pyroptosis of MCF7 Cells Induced by the Secreted Factors of hUCMSCs

Human umbilical cord mesenchymal stem cells (hUCMSCs) are superior to other sources of mesenchymal stem/stromal cells (MSCs), and they are used as a novel tool for cell-based cancer therapy. However, the mechanism underlying hUCMSC-induced cancer cell death is not clear. In the present study, we aimed to evaluate the effect of secreted factors of hUCMSCs on the breast cancer cell line MCF7 by exposing them to the conditioned medium (CM) of hUCMSCs. We evaluated the morphological changes, cell viability, cell cycle, apoptosis, DNA fragmentation, and interleukin-1β (IL-1β) secretion of CM-exposed MCF7 cells. The results showed that the secreted factors of hUCMSCs could cause MCF7 cell death by inducing pyroptosis. We also sequenced the total RNA, and the differentially expressed genes (DEGs) were subjected to the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. A total of 2597 (1822 upregulated and 775 downregulated) genes were identified and 14 pathways were significantly enriched. The results showed that the expression of the pyroptosis-related genes NLRP1 and CASP4 and the inflammation-related pathways changed significantly in MCF7 cells exposed to the CM. To the best of our knowledge, this study is the first to report that the secreted factors of hUCMSCs can cause MCF7 cell pyroptosis. Furthermore, it is the first to examine the global gene expression in MCF7 cells exposed to CM. These results will provide valuable information for further studies on the mechanism of MCF7 cell pyroptosis induced by the secreted factors of hUCMSCs. It will also help understand the effect of hUCMSCs on cell-based breast cancer therapy.

Mycoplasma pneumoniae and toll-like receptors: A mutual avenue

Mycoplasma pneumoniae is an intracellular bacterium leading to several complications in humans. M. pneumoniae is cleared in some cases and induces complications in others. The main responsible mechanisms regarding the controversy are yet to be cleared. Toll-like receptors (TLRs) are the important cell membrane and intracellular receptors which recognize a wide range of microbial macromolecules. The roles of TLRs in the eradication of several pathogens and also induction of their related complications have been demonstrated. This review article presents recent data about the roles of TLRs in the induction of immune responses which lead to M. pneumoniae eradication and related complications.

The roles of toll like receptor 3, 7 and 8 in allergic rhinitis pathogenesis

Allergic rhinitis, as an allergic and nasal hypersensitivity disease, is associated with the inflammation of nasal mucosa. It appears that innate immune receptors are the important risk factors in the pathogenesis of the inflammatory disease. Toll-like receptors (TLRs) are the most important receptors of innate immunity; their crucial roles in the recognition of allergens and subsequently pathogenesis of allergic diseases have been evaluated recently. TLR3, 7 and 8 are the intracellular members of the innate immune receptors and recognize intracellular single and double strand RNAs. This review article collected the investigations regarding the roles of TLR3, 7 and 8 in the allergic rhinitis pathogenesis.

IL-17A and IL-23: plausible risk factors to induce age-associated inflammation in Alzheimer's disease

Background: Aging and its complications such as Alzheimer's disease (AD) are associated with chronic low-grade inflammation entitled age-associated inflammation. However, the main mechanisms whichinduce age-associated inflammation in aging and AD are yet to beclarified. L-23/IL-17A axis plays important roles in the induction of inflammation and consequently autoimmune disease. This review evaluates the main roles played by IL-17A, IL-23, and IL-17A/IL-23 axis in the pathogenesis of age-associated inflammation in AD patients. Result: IL-23/IL-17A axis, is an important factor participate in the pathogenesis of age-associated inflammation. The genetic variations and microbial infection can be considered as the most important candidates to induce AD via upregulation of IL-17A. IL-17A also deteriorates AD via induction by amyloid-β. IL-17A participates in the induction of AD by increasing neutrophils infiltration to brain, induction of neuroinflammation, increase in FASL, and amyloid-βdeposition as well as activation of microglia. Conclusions: Due to the important roles played by IL-23/IL-17A axis in AD pathogenesis, it can be considered as a target for immunotherapy against AD. Abbreviations: Aβ: β-Amyloid; AD: Alzheimer's disease; CD: cluster of differentiation; DAMPs: Damage-associated molecular patterns; DCs: dendritic cells; HLA: human leukocyte antigen; NF-κB: nuclear factor kappa-light-chain-enhancer of activated B cells; RAR: retinoic-acid receptor; RORγt: RAR-related orphan receptor gamma t; SAMP8: senescence-accelerated mouse prone 8 strain; TGF-β: tumor growth factor-β; TLRs: toll-like receptors.

Vitamin D and toll like receptors

It has been demonstrated that vitamin D (VD) significantly modulates immune responses. Toll like receptors (TLRs) are the main innate immunity receptors which are expressed on the cell membrane and intracellular vesicles and recognize several pathogen associated molecular patterns (PAMPs) and damage associated molecular patterns (DAMPs) to induce immune responses. Based on the important roles played by TLRs in physiologic and pathologic functions of immune responses and due to the immunomodulatory functions of VD, it has been hypothesized that VD may present its immunomodulatory functions via modulation of TLRs. This review article collates recent studies regarding the interactions between VD and TLRs and discussed the controversial investigations.

TLR2 Expression in Peripheral CD4+ T Cells Promotes Th17 Response and Is Associated with Disease Aggravation of Hepatitis B Virus-Related Acute-On-Chronic Liver Failure

Th17 responses have been shown to play crucial roles in the pathogenesis of hepatitis B virus (HBV)-associated acute-on-chronic liver failure (ACLF). The mechanism underlying the enhanced Th17 responses in these patients remains largely unclear. Here we investigated toll-like receptors (TLRs) expression in peripheral T cells and their roles in Th17 cell differentiation and disease aggravation in ACLF patients. 18 healthy subjects (HS), 20 chronic HBV-infected (CHB) patients, and 26 ACLF patients were enrolled and examined for TLRs expression in peripheral blood mononuclear cells (PBMCs). The correlations of T cell TLR2 expression with the antigen non-specific Th17 responses and disease aggravation, as well as the Th17 response to TLR2 ligand stimulation were evaluated in ACLF patients. Compared to HS and CHB patients, ACLF patients showed a distinct TLRs expression pattern in PBMCs. Significantly increased TLR2 expression in T cells was observed in ACLF patients. The TLR2 expression in CD4+ T cells was correlated with the Th17 responses and the clinical markers for disease aggravation in ACLF patients. Moreover, TLR2 ligands stimulation promoted Th17 cell differentiation and response in PBMCs of ACLF patients. These findings implicate that TLR2 signaling plays critical roles in Th17 cell differentiation and disease aggravation of HBV-related ACLF.

Association of S100 calcium-binding protein A12, receptor for advanced glycation endproducts, and nuclear factor-κB expression with inflammation in pulp tissues from tooth caries

AIM

S100 calcium-binding protein A1 (S100A12) is a pro-inflammatory molecule which is secreted during inflammation and induces chemotaxis and the production of pro-inflammatory cytokines via interaction with receptor for advanced glycation endproducts (RAGE) and subsequent, activation of nuclear factor-κB (NF-κB). The present study was designed to determine the expression levels of S100A12, RAGE, and NF-κB in the inflamed pulp of carried teeth.

METHODS

In the present study, mRNA from 50 inflamed pulp and 50 healthy pulp were used for expression studies using real-time polymerase chain reaction. The expression levels of S100A12, RAGE, and NF-κB were compared between inflamed and healthy tissues.

RESULTS

The results revealed that the expression of S100A12, but not of RAGE or NF-κB, was significantly decreased in inflamed pulp when compared to healthy pulp. mRNA levels of RAGE were also increased in the inflamed pulp taken from men when compared with women.

CONCLUSION

The results suggest that S100A12 does not participate in the induction of inflammation in dental pulp. However, RAGE can participate in the inflammation in the pulp of males.

Innate immunity related pathogen recognition receptors and chronic hepatitis B infection

Innate immunity consists of several kinds of pathogen recognition receptors (PRRs), which participate in the recognition of pathogens and consequently activation of innate immune system against pathogens. Recently, several investigations reported that PRRs may also play key roles in the induction/stimulation of immune system related complications in microbial infections. Hepatitis B virus (HBV), as the main cause of viral hepatitis in human, can induce several clinical forms of hepatitis B and also might be associated with hepatic complications such as cirrhosis and hepatocellular carcinoma (HCC). Based on the important roles of PRRs in the eradication of microbial infections including viral infections and their related complications, it appears that the molecules may be a main part of immune responses against viral infections including HBV and participate in the HBV related complications. Thus, this review article has brought together information regarding the roles of PRRs in immunity against HBV and its complications.

Toll like receptor 4 and hepatocellular carcinoma; A systematic review

INTRODUCTION

Toll like receptor 4 (TLR4) is an extracellular pathogen recognition receptor (PRR) which recognizes a wide range of pathogens and damage associated molecular patterns (PAMPs and DAMPs). It can activate intracellular signaling and consequently transcription factors which participate in transcription from either immune related or malignancy genes. Thus, it has been hypothesized that TLR4 may be a cause of hepatocellular carcinoma (HCC). This article has reviewed the roles of TLR4 in the pathogenesis of HCC.

METHOD

"TLR4", "hepatocellular carcinoma", "liver tumor" and "liver cancer" were used as key words for searching in Scopus, Google Scholar and MEDLINE scientific databases.

RESULTS

Most of the investigations documented the roles of TLR4 in induction of HCC via several mechanisms including increased number of T regulatory lymphocytes and liver resident follicular helper like cells, increased production of pro-inflammatory and malignancy related molecules including cytokines, NANOG, Caspase-1, Ephrin-A1, NO and BCL6. TLR4 participates in the proliferation of the cells and also production of the molecules in both chronic infectious and non-infectious inflammatory diseases.

DISCUSSION

TLR4 is an innate immunity receptor which plays a pathogenic role during chronic inflammation and can induce HCC in human.

Clinical and pathological significance of myeloid differentiation factor 88 expression in human hepatocellular carcinoma tissues

The innate immune system, which includes toll-like receptor (TLR) signaling, plays an important role in inflammation and oncogenesis. Although TLR common adaptor myeloid differentiation factor 88 (MyD88) is known to have multiple effects on carcinogenesis, the role of MyD88 in hepatocarcinogenesis remains unknown. In this study, MyD88 expression was examined in 105 samples of human hepatocellular carcinoma (HCC) tissue by immunohistochemistry, Western blot, and quantitative reverse-transcriptase polymerase chain reaction methods. The relationships between MyD88 expression and clinical and pathological parameters were analyzed. The results showed that attenuated expression of MyD88 in HCC tissue tumor cells was significantly related to hepatitis B virus infection, large tumor size, positive vascular invasion, and intrahepatic metastasis (P < 0.05). Western blot analysis of MyD88 protein in nine normal livers and 28 HCCs showed gender disparity (P < 0.01, P < 0.05), and attenuated expression in cirrhotic livers (P < 0.05). Low expression of MyD88 mRNA was evident in HCCs with vascular invasion (P < 0.01). In contrast to previous reports, these results suggest that attenuated expression of MyD88 in HCC is associated with tumor progression.

Toll like receptor 4: an important molecule in recognition and induction of appropriate immune responses against Chlamydia infection

Chlamydia species are obligate intracellular pathogens causing different infectious diseases particularly asymptomatic genital infections and are also responsible for a wide range of complications. Previous studies showed that there are different immune responses to Chlamydia species and their infections are limited to some cases. Moreover, Chlamydia species are able to alter immune responses through modulating the expression of some immune system related molecules including cytokines. Toll like receptors (TLRs) belonge to pathogen recognition receptors (PRRs) and play vital roles in recognition of microbes and stimulation of appropriate immune responses. Therefore, it appears that TLRs may be considered as important sensors for recognition of Chlamydia and promotion of immune responses against these bacterial infections. Accordingly, TLR4 detects several microbial PAMPs such as bacterial lipopolysacharide (LPS) and subsequently activates transcription from pro-inflammatory cytokines in both MYD88 and TRIF pathways dependent manner. The purpose of this review is to provide the recent data about the status and major roles played by TLR4 in Chlamydia species recognition and promotion of immune responses against these infections and also the relationship between TLR4 activities and pathogenesis of Chlamydia infections.

Chronoinflammaging in Alzheimer; A systematic review on the roles of toll like receptor 2

Aging is associated with a range of chronic low-grade inflammation (Chronoinflammaging) which may play a significant role in some chronic inflammatory based diseases, such as Alzheimer disease (AD). However, the events which lead to the induction of chronoinflammaging in AD are yet to be clarified. It has been proposed that the recognition of endogenous ligands by pathogen recognition receptors (PRRs) may be involved in the induction of chronoinflammaging. Toll like receptors (TLRs) are a family of PRRs which recognize endogenous damage associated molecular patterns (DAMPs) and subsequently induce inflammation. Therefore, TLRs are worthy of investigation to elucidate their roles in chronoinflammaging associated AD. This review article explores the main roles played by TLR2 in the pathogenesis of chronoinflammaging in patients suffering from AD.

Hepatitis B Surface Antigen Promotes the Invasion of Hepatitis B Virus-Related Hepatocellular Carcinoma Cells by Upregulation of Toll-Like Receptor 2

Hepatitis B virus (HBV) infection is one of the major risk factors leading to the development of hepatocellular carcinoma (HCC). Hepatitis B surface antigen (HBsAg) plays a pivotal role in HBV-related HCC pathogenesis, and Toll-like receptor (TLR) 2 is also considered to mediate tumor progression. However, the interaction between HBsAg and TLR2 in HCC progression remains unclear. Thus, the aim of the study was to explore the effect of HBsAg-TLR2 pathway on growth and invasion of HBV-related HCC cells and examine the potential mechanisms been involved. The expression of TLR2 was measured in two different HCC cell lines (HepG2 and HepG2.2.15) with or without recombinant HBsAg by real-time reverse polymerase chain reaction and Western blot. Cellular proliferation, invasion, cytokine productions, and downstream signaling pathways were also measured in TLR2-silencing HepG2.2.15 cells in response to HBsAg stimulation. The mRNA and protein levels of TLR2 were significantly elevated in HepG2.2.15 cells than those in HepG2 cells. HBsAg simulation increased proinflammatory cytokine production and invasion of HepG2.2.15 cells, while this process was inhibited by TLR2 silence. However, TLR2 siRNA transfection alone did not affect the bioactivities of tumor cells. Moreover, HBsAg increased expression of MyD88 and phosphorylation of NF-κB p50 and p38MAPK. Downregulation of TLR2 inhibited HBsAg-induced MyD88 and p-NF-κB, but not p-p38MAPK in HepG2.2.15 cells. In conclusion, HBsAg stimulation promotes the invasion of HBV-related HCC cells. TLR2/MyD88/NF-κB signaling pathway may be involved in this procession by upregulation of cytokine production. The interaction between TLR2 and HBsAg may contribute to the poor prognosis of HBV-related HCC.

Toll-like receptor 2 and type 2 diabetes

Innate immunity plays a crucial role in the pathogenesis of type 2 diabetes and related complications. Since the toll-like receptors (TLRs) are central to innate immunity, it appears that they are important participants in the development and pathogenesis of the disease. Previous investigations demonstrated that TLR2 homodimers and TLR2 heterodimers with TLR1 or TLR6 activate innate immunity upon recognition of damage-associated molecular patterns (DAMPs). Several DAMPs are released during type 2 diabetes, so it may be hypothesized that TLR2 is significantly involved in its progression. Here, we review recent data on the important roles and status of TLR2 in type 2 diabetes and related complications.

Evaluating Effect of Mesenchymal Stem Cells on Expression of TLR2 and TLR4 in Mouse DCs

PURPOSE

Mesenchymal stem cells (MSCs) are multipotent cells and recent findings suggest immunomodulatory effect of them on immune cells including T cells and dendritic cells (DCs). DCs are the most potent antigen presenting cells. It seems because of immunoregulatory properties of MSCs, they can affect the maturation and differentiation of DCs. DCs express a kind of surface receptors called toll-like receptors (TLRs) and play a key role in maturation process and activation of DCs. The aim of this study was to evaluate expression of TLR2 and TLR4 on DCs after exposure to mesenchymal stem cell's supernatant in culture media containing LPS and devoid of it.

METHODS

In this experimental study, MSCs and DCs were extracted from adult Balb/c mouse bone marrow and spleen, respectively. MSCs supernatant were collected 24 and 48 h after 5(th) passage, and in adjusted with DCs culture. Isolated DCs were co-cultured with MSCs supernatant, incubation time were 24 and 48 hours. mRNA levels of TLR2 and TLR4 were evaluated using real time PCR technique.

RESULTS

The results demonstrated that although, expressions of these two receptors were up-regulated in culture media lacking LPS in comparison with the control group but the increase was not significant. There were no significant associations between LPS stimulated DCs with and without MSCs supernatants.

CONCLUSION

According to the results presented here, it appears that TLR2 and TLR4 gene expressions on the DCs are not affected by MSCs supernatant.

Innate immune targets of hepatitis B virus infection

Approximately 400 million people are chronically infected with hepatitis B virus (HBV) globally despite the widespread immunization of HBV vaccine and the development of antiviral therapies. The immunopathogenesis of HBV infection is initiated and driven by complexed interactions between the host immune system and the virus. Host immune responses to viral particles and proteins are regarded as the main determinants of viral clearance or persistent infection and hepatocyte injury. Innate immune system is the first defending line of host preventing from virus invasion. It is acknowledged that HBV has developed active tactics to escape innate immune recognition or actively interfere with innate immune signaling pathways and induce immunosuppression, which favor their replication. HBV reduces the expression of pattern-recognition receptors in the innate immune cells in humans. Also, HBV may interrupt different parts of antiviral signaling pathways, leading to the reduced production of antiviral cytokines such as interferons that contribute to HBV immunopathogenesis. A full comprehension of the mechanisms as to how HBV inactivates various elements of the innate immune response to initiate and maintain a persistent infection can be helpful in designing new immunotherapeutic methods for preventing and eradicating the virus. In this review, we aimed to summarize different branches the innate immune targeted by HBV infection. The review paper provides evidence that multiple components of immune responses should be activated in combination with antiviral therapy to disrupt the tolerance to HBV for eliminating HBV infection.

Controversial roles played by toll like receptor 4 in urinary bladder cancer; A systematic review

INTRODUCTION

Urinary bladder cancer (UBC) is a prevalent human cancer. The main mechanisms which lead to eradication or progression the disease has yet to be clarified. Toll like receptor (TLR) 4 is a membrane receptor which is expressed either on immune cells or tumor cells. This review article was aimed to clear the main mechanisms played by TLR4 and its related intracellular pathways on outcome of UBC.

METHOD

PubMed, Scopus and Google scholar databases have been used for searching related research articles which have evaluated the roles played by TLR4 and its related intracellular pathways on outcome of UBC.

RESULTS

Collected information from the related articles revealed that TLR4 either participates in induction of immune responses against UBC or development of the malignancy. There are limited investigations regarding the genetic variations of TLR4 in UBC.

DISCUSSION

According to the results it seems that TLR4/ligands interaction outcome is dependent on several factors including TLR4 ligand doses, interaction of TLR4 with its ligands on immune cells or tumor cells, and other TLRs/ligand interaction simultaneously.

Macrophage-activating lipopeptide-2 downregulates the expression of ATP-binding cassette transporter A1 by activating the TLR2/NF-кB/ZNF202 pathway in THP-1 macrophages

Macrophage-activating lipopeptide-2 (MALP-2) has been shown to promote the development of atherosclerosis. ATP-binding cassette transporter A1 (ABCA1), a transmembrane protein, plays a critical role in mediating cholesterol export from macrophages to apolipoprotein A-I (apoA-I). However, whether MALP-2 can regulate the expression of ABCA1 is still largely unknown. The aim of this study was to explore the effects of MALP-2 on ABCA1 expression in THP-1 macrophages and the underlying mechanisms. Our results showed that the treatment of cells with MALP-2 decreased ABCA1 level and suppressed cholesterol efflux in both concentration- and time-dependent manners. The contents of intracellular cholesterol were significantly increased in the presence of MALP-2. Moreover, MALP-2-mediated inhibition of ABCA1 expression was abolished by siRNA of either Toll-like receptor 2 (TLR2) or nuclear factor κB (NF-κB). A similar effect was produced by treatment with the NF-κB inhibitor pyrrolidine dithiocarbamate. In addition, MALP-2-induced activation of NF-κB markedly increased zinc finger protein 202 (ZNF202) level, and ZNF202 siRNA impaired the effects of MALP-2 on ABCA1 expression. Taken together, these results suggest that MALP-2 can decrease ABCA1 expression and subsequent cholesterol efflux through activation of the TLR2/NF-κB/ZNF202 signaling pathway in THP-1 macrophages.

Innate Immunity and BK Virus: Prospective Strategies

Recent information demonstrated that BK virus reactivation is a dominant complication after kidney transplantation, which occurs because of immunosuppression. BK virus reactivation is the main reason of transplanted kidney losing. Immune response against BK virus is the major inhibitor of the virus reactivation. Therefore, improving our knowledge regarding the main parameters that fight against BK viruses can shed light on to direct new treatment strategies to suppress BK infection. Innate immunity consists of numerous cell systems and also soluble molecules, which not only suppress virus replication, but also activate adaptive immunity to eradicate the infection. Additionally, it appears that immune responses against reactivated BK virus are the main reasons for induction of BK virus-associated nephropathy (BKAN). Thus, improving our knowledge regarding the parameters and detailed mechanisms of innate immunity and also the status of innate immunity of the patients with BK virus reactivation and its complications can introduce new prospective strategies to either prevent or as therapy of the complication. Therefore, this review was aimed to collate the most recent data regarding the roles played by innate immunity against BK virus and also the status of innate immunity in the patients with reactivation BK virus and BKAN.

Kupffer Cells Support Hepatitis B Virus-Mediated CD8+ T Cell Exhaustion via Hepatitis B Core Antigen-TLR2 Interactions in Mice

Hepatitis B virus (HBV) persistence is a fundamental process in chronic HBV infection and a key factor in all related liver diseases; however, the mechanisms have yet to be elucidated. We studied the role of TLR2 in HBV persistence using a well-established HBV-carrier mouse model generated by hydrodynamically injecting a phospho-adeno-associated virus/HBV1.2 plasmid into mice. We found that a genetic deficiency in TLR2 improves HBV elimination, whereas activating TLR2 led to more stable HBV persistence, suggesting that TLR2 activation is critical in HBV persistence. Furthermore, we noted that TLR2 activation could inhibit CD8(+) T cell function, causing the exhaustion phenotype in HBV-carrier mice, because TLR2 deficiency might rescue CD8(+) T cell function in a cellular adoptive experiment. TLR2 expression on Kupffer cells (KCs) was upregulated in HBV-carrier mice, which accounts for HBV persistence, because the difference in anti-HBV immunity between HBV-carrier wild-type and Tlr2(-/-) mice did not exist after KC depletion. In addition, similar to TLR2 deficiency, after KC depletion, CD8(+) T cells were more efficiently activated in HBV-carrier mice, leading to rapid HBV elimination. KCs produced more IL-10 upon TLR2 activation in response to direct hepatitis B core Ag stimulation, and the elevated IL-10 inhibited CD8(+) T cell function in HBV-carrier mice, because IL-10 deficiency or anti-IL-10R treatment resulted in CD8(+) T cells with stronger antiviral function. In conclusion, KCs support liver tolerance by inducing anti-HBV CD8(+) T cell exhaustion via IL-10 production after TLR2 activation by hepatitis B core Ag stimulation.