TLR3 plays significant roles against hepatitis B virus

Do CCR5 (CCR5Δ32) and TLR3 (RS5743313) gene polymorphisms prevent chronic hepatitis B infection?

Hepatitis B virus (HBV) is still a significant health problem in human. HBV severity or sensitivity of patients may be based on the individual genetic factors significantly. The aim of this study is to investigate the association of CCR5 (CCR5Δ32), TLR3 (rs5743313) functional gene polymorphisms, interferon-gamma (IFN-ɣ) level in HBV infection, which are thought to play an important role in innate and acquired immunity in patients who have undergone HBV seroconversion and those who have chronic hepatitis B disease and receive treatment. One hundred patients who are became naturally immune against HBV infection (HBsAg negative, anti-HBc IgG, and anti-HBs IgG positive), and 100 patients with chronic hepatitis B infection (>6 months HBsAg positive) who are receiving oral antiviral therapy were compared for CCR5Δ32, TLR3 (rs5743313) genotypes and serum IFN-ɣ level. It was found that CCR5Δ32 polymorphism (Wt/Δ32 and Δ32/Δ32) was significantly higher in the chronic hepatitis B group (p = 0.048) but not for TLR3 gene polymorphism. However, serum IFN-ɣ level was significantly higher in the HBV seroconversion group (75 ± 89 ng/ml) than in the chronic hepatitis B group (4.35 ± 17.27 ng/ml) (p < 0.001). In conclusion, a higher CCR5Δ32 allele frequency in patients with chronic hepatitis B might be considered as a marker of progression to chronic hepatitis.

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.

Exploring the mechanism of Qinbaiqingfei-concentrate pills in the treatment of Mycoplasma pneumoniae pneumonia from the perspective of intestinal microbiota and mucosal immunity

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine categorizes Mycoplasma pneumoniae pneumonia as "lung heat", and treatment with heat clear and detoxify. Traditional Chinese medicine believes that the lungs and intestines come from the same source, and the intestine is related to pneumonia. This is the same as the gut-lung axis theory. Qinbaiqingfei concentrate pills (QBs) were modified based on Cough San in the ancient medical book Medical Awareness. It clears lung heat, moisturizes the lungs and dredges collaterals, and has a good ability to treat Mycoplasma pneumoniae.

AIM OF THE STUDY

A rat model of Mycoplasma pneumoniae was established. From the aspect of intestinal flora and mucosal immunity, the potential mechanism of the QBs was researched.

MATERIALS AND METHODS

First, the content of Mycoplasma pneumoniae in lung tissue and the levels of the inflammatory factors IL-4, IL-10, TNF-α and INF-γ were detected. To determine the expression of NF-kB related proteins in lung tissue, which can understand the ability in treating disease. Next, metagenomic sequencing was performed to detect changes in short-chain fatty acids, proving the ability of the drug to regulate intestinal microecology. Finally, HDAC, LPS, SIgA, etc. were detected to facilitate the correlation of the overall experimental indicators.

RESULTS

QBs reduces the levels of IL-4, IL-10, TNF-α and INF-γ in the serum by inhibiting the expression of MyD88, IKKα, IκBα, and NF-κB p65 in lung tissue. In addition, QBs restores the ratio of gram-negative bacteria to gram-positive bacteria in the intestine, restores the secretion of acetic acid, propionic acid, butyric acid, isobutyric acid and isovaleric acid, and promotes the secretion of NF-κB p65 and SIgA by HDAC1/3. The result is that the lung tissue is repaired and the proliferation of Mycoplasma pneumoniae is inhibited.

CONCLUSIONS

From the "gut-lung axis", a new research perspective was discovered. QBs intervened in the intestines and lungs to treat Mycoplasma pneumoniae.

Transcriptomic profiling of clobetasol propionate-induced immunosuppression in challenged zebrafish embryos

In the ecotoxicological hazard assessment of chemicals, the detection of immunotoxicity is currently neglected. This is mainly due to the complexity of the immune system and the consequent lack of standardized procedures and markers for the comprehensive assessment of immunotoxic modes of action. In this study, we present a new approach applying transcriptome profiling to an immune challenge with a mixture of pathogen-associated molecular patterns (PAMPs) in zebrafish embryos, analyzing differential gene expression during acute infection with and without prior exposure to the immunosuppressive drug clobetasol propionate (CP). While PAMP injection itself triggered biological processes associated with immune activation, some of these genes were more differentially expressed upon prior exposure to CP than by immune induction alone, whereas others showed weaker or no differential regulation in response to the PAMP stimulus. All of these genes responding differently to PAMP after prior CP exposure showed additivity of PAMP- and CP-induced effects, indicating independent regulatory mechanisms. The transcriptomic profiles suggest that CP impaired innate immune induction by attenuating the response of genes involved in antigen processing, TLR signaling, NF-КB signaling, and complement activation. We propose this approach as a powerful method for detecting gene biomarkers for immunosuppressive modes of action, as it was able to identify alternatively regulated processes and pathways in a sublethal, acute infection zebrafish embryo model. This allowed to define biomarker candidates for immune-mediated effects and to comprehensively characterize immunosuppression. Ultimately, this work contributes to the development of molecular biomarker-based environmental hazard assessment of chemicals in the future.

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.

Potential value of pharmacological agents acting on toll-like receptor (TLR) 7 and/or TLR8 in COVID-19

The COVID-19 pandemic is an ongoing global pandemic of coronavirus disease 2019 as an atypical type of viral pneumonia caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Many potential pharmacotherapies are currently being investigated against this disease. This article points to and justifies, the importance of investigating the potential therapeutic value of pharmacological agents acting on Toll-like Receptor (TLR) 7 and/or TLR8 as double-edged swords combating COVID-19. Induction of TLR7 and/or TLR8 may be investigated as a strategy to stimulate immunity and may be added to anti-COVID19 vaccines to cope with their current viral escape challenge. TLR7 stimulation may not only help viral clearance through Th1 antiviral responses but may also provide beneficial broncho- and vaso-dilatory, as well as, anti-inflammatory effects. Pharmacological compounds acting as TLR7 and/or TLR8 agonists may be of value if used by frontline healthcare workers with comorbidities who demonstrate mild symptoms of the disease. On the other hand, TLR7 and/or TLR8 antagonists may be used in combination with immune-modulatory/anti-inflammatory drugs in severe cases of the disease, with potential synergistic effects that could also help in reducing the doses of such therapies, and consequently their adverse effects.

•

There is potential value in development of TLR7/8 agonists/antagonists as double-edged swords combating COVID-19.

•

TLR7/8 agonists, as immune-stimulants in mild disease, may also be added to preventive vaccines acting against viral escape.

•

TLR7/8 antagonists may be combined with immune-suppressants in severe cases for potential synergism and minimized toxicity.

A Study Based on Metabolomics, Network Pharmacology, and Experimental Verification to Explore the Mechanism of Qinbaiqingfei Concentrated Pills in the treatment of Mycoplasma Pneumonia

Qinbaiqingfei concentrated pills (QB) are a commonly used medicine for the treatment of mycoplasma pneumonia in China, and the mechanism of action of QB needs to be studied further. Therefore, we use a combination of metabolomics and network pharmacology to clarify the mechanism of QB. Nontarget metabolomics studies were performed on rat serum, urine, and lung tissues, and 56 therapeutic biomarkers were found. Subsequently, the components of QB absorbed into the blood and lung tissues were clarified, and based on this finding, the core target of network pharmacology was predicted. The enrichment analysis of biomarkers–genes finally confirmed their close relationship with the NF-κB signaling pathway. By western blotting expression of the proteins in the lung tissue–related signaling pathways, it is finally confirmed that QB inhibits the NF-κB signaling pathway through SIRT1, IL-10 and MMP9, CTNNB1, EGFR, and other targets. It plays a role in regulating immunity, regulating metabolism, and treating diseases.

Toll-like receptor 2 signaling in liver pathophysiology

Chronic liver diseases (CLD) are among the major cause of mortality and morbidity worldwide. Despite current achievements in the area of hepatitis virus, chronic alcohol abuse and high-fat diet are still fueling an epidemic of severe liver disease, for which, an effective therapy has yet not been discovered. In particular, the therapeutic regimens that could prevent the progression of fibrosis and, in turn, aid cirrhotic liver to develop a robust regenerative capability are intensively needed. To this context, a better understanding of the signaling pathways regulating hepatic disease development may be of critical value. In general, the liver responds to various insults with an orchestrated healing process involving variety of signaling pathways. One such pathway is the TLR2 signaling pathway, which essentially regulates adult liver pathogenesis and thus has emerged as an attractive target to treat liver disease. TLR2 is expressed by different liver cells, including Kupffer cells (KCs), hepatocytes, and hepatic stellate cells (HSCs). From a pathologic perspective, the crosstalk between antigens and TLR2 may preferentially trigger a distinctive set of signaling mechanisms in these liver cells and, thereby, induce the production of inflammatory and fibrogenic cytokines that can initiate and prolong liver inflammation, ultimately leading to fibrosis. In this review, we summarize the currently available evidence regarding the role of TLR2 signaling in hepatic disease progression. We first elaborate its pathological involvement in liver-disease states, such as inflammation, fibrosis, and cirrhosis. We then discuss how therapeutic targeting of this pathway may help to alleviate its disease-related functioning.

Toll-like receptor 3 (TLR3) regulation mechanisms and roles in antiviral innate immune responses

Toll-like receptor 3 (TLR3) is a member of the TLR family, mediating the transcriptional induction of type I interferons (IFNs), proinflammatory cytokines, and chemokines, thereby collectively establishing an antiviral host response. Studies have shown that unlike other TLR family members, TLR3 is the only RNA sensor that is utterly dependent on the Toll-interleukin-1 receptor (TIR)‍-domain-containing adaptor-inducing IFN-‍β (TRIF). However, the details of how the TLR3-TRIF signaling pathway works in an antiviral response and how it is regulated are unclear. In this review, we focus on recent advances in understanding the antiviral mechanism of the TRIF pathway and describe the essential characteristics of TLR3 and its antiviral effects. Advancing our understanding of TLR3 may contribute to disease diagnosis and could foster the development of novel treatments for viral diseases.

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.

The effect of IFN-β 1a on expression of MDA5 and RIG-1 in multiple sclerosis patients

The aims of this study were to compare mRNA levels of melanoma differentiation-associated protein 5 (MDA5) and retinoic acid-inducible gene 1 (RIG-1) in multiple sclerosis (MS) patients in comparison to the healthy controls as well as investigating the effects of IFN-β 1a on the expression of these molecules. In this study, mRNA levels of MDA5 and RIG-1 in peripheral leukocytes of 30 new cases of MS patients and 35 healthy controls were evaluated using the real-time-PCR method. mRNA levels of MDA5 and RIG-1 were determined in the MS patients 6 months after treatment with standard doses of IFN-β 1a. mRNA levels of MDA5 and RIG-1 were significantly decreased in the MS patients in comparison to the healthy controls. The analysis also revealed that IFN-β 1a therapy leads to the upregulation of RIG-1, but not MDA5, in the total MS patients and the female group. MS patients suffer from insufficient expression of MDA5 and RIG-1, and IFN-β 1a therapy results in the upregulation of RIG-1 in the patients, especially in the female patients. Thus, it seems that IFN-β 1a not only decreased pathogenic inflammatory responses but also modulated the expression of RIG-1 to protect the patients from infectious diseases and upregulation of IFN-I in a positive feedback.

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.

CpG Adjuvant in Allergen-Specific Immunotherapy: Finding the Sweet Spot for the Induction of Immune Tolerance

Prevalence and incidence of IgE-mediated allergic diseases have increased over the past years in developed and developing countries. Allergen-specific immunotherapy (AIT) is currently the only curative treatment available for allergic diseases that has long-term efficacy. Although AIT has been proven successful as an immunomodulatory therapy since its beginnings, it still faces several unmet needs and challenges today. For instance, some patients can experience severe side effects, others are non-responders, and prolonged treatment schedules can lead to lack of patient adherence and therapy discontinuation. A common strategy to improve AIT relies on the use of adjuvants and immune modulators to boost its effects and improve its safety. Among the adjuvants tested for their clinical efficacy, CpG oligodeoxynucleotide (CpG-ODN) was investigated with limited success and without reaching phase III trials for clinical allergy treatment. However, recently discovered immune tolerance-promoting properties of CpG-ODN place this adjuvant again in a prominent position as an immune modulator for the treatment of allergic diseases. Indeed, it has been shown that the CpG-ODN dose and concentration are crucial in promoting immune regulation through the recruitment of pDCs. While low doses induce an inflammatory response, high doses of CpG-ODN trigger a tolerogenic response that can reverse a pre-established allergic milieu. Consistently, CpG-ODN has also been found to stimulate IL-10 producing B cells, so-called B regulatory cells (Bregs). Accordingly, CpG-ODN has shown its capacity to prevent and revert allergic reactions in several animal models showing its potential as both preventive and active treatment for IgE-mediated allergy. In this review, we describe how CpG-ODN-based therapies for allergic diseases, despite having shown limited success in the past, can still be exploited further as an adjuvant or immune modulator in the context of AIT and deserves additional attention. Here, we discuss the past and current knowledge, which highlights CpG-ODN as a potential adjuvant to be reevaluated for the enhancement of AIT when used in appropriate conditions and formulations.

Nuclear Sensor Interferon-Inducible Protein 16 Inhibits the Function of Hepatitis B Virus Covalently Closed Circular DNA by Integrating Innate Immune Activation and Epigenetic Suppression

BACKGROUND AND AIMS

Nuclear-located covalently closed circular DNA (cccDNA) of hepatitis B virus (HBV) is a determining factor for HBV persistence and the key obstacle for a cure of chronic hepatitis B. However, it remains unclear whether and how the host immune system senses HBV cccDNA and its biological consequences.

APPROACH AND RESULTS

Here, we demonstrated that interferon-inducible protein 16 (IFI16) could serve as a unique innate sensor to recognize and bind to HBV cccDNA in hepatic nuclei, leading to the inhibition of cccDNA transcription and HBV replication. Mechanistically, our data showed that IFI16 promoted the epigenetic suppression of HBV cccDNA by targeting an interferon-stimulated response element (ISRE) present in cccDNA. It is of interest that this ISRE was also revealed to play an important role in IFI16-activated type I interferon responses. Furthermore, our data revealed that HBV could down-regulate the expression level of IFI16 in hepatocytes, and there was a negative correlation between IFI16 and HBV transcripts in liver biopsies, suggesting the possible role of IFI16 in suppressing cccDNA function under physiological conditions.

CONCLUSIONS

The nuclear sensor IFI16 suppresses cccDNA function by integrating innate immune activation and epigenetic regulation by targeting the ISRE of cccDNA, and IFI16 may present as a therapeutic target against HBV infection.

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.

Toll-Like Receptor 4 as an Immune Receptor Against Mycobacterium tuberculosis: A Systematic Review

OBJECTIVE

To review the main Mycobacterium tuberculosis (Mtb) pathogen-associated molecular patterns (PAMPs) and the roles played by toll-like receptor (TLR)4 in determination of Mtb infection outcome.

METHODS

Several scientific databases, including Scopus, PubMed, and Google Scholar, were used for searching appropriate research articles from the literature for information on our topic.

RESULTS

TLR4 plays positive roles in induction of immune responses against Mtb and participates in eradication of the infection. Some limited investigations approved the roles of TLR4 in induction of apoptosis in macrophages during tuberculosis (TB) and attenuation of immune responses in some situations.

CONCLUSIONS

TB outcome appears to be dependent on TLR4/Mtb interaction and several factors, including bacterial load and immune or nonimmune cells, as hosts. Also, other TLR/Mtb interactions can affect TLR4 responses.

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.

TLR3 and TLR4 SNP variants in the liver disease resulting from hepatitis B virus and hepatitis C virus infection

BACKGROUND

Chronic infection with hepatitis B (HBV) and C virus (HCV) is linked with a pro-inflammatory state, predisposing to cirrhosis and liver cancer, particularly hepatocellular carcinoma (HCC). A role for Toll-like receptor (TLR) signalling in hepatocarcinogenesis was recently documented. We hypothesised a link TLR3 and TLR4 polymorphisms and HCC, as surrogates for the significance of TLR signalling in the promotion and initiation of HCC.

MATERIALS AND METHODS

We recruited 174 HCV-infected patients, 100 HBV-infected patients and 360 healthy control subjects. TLR3 (rs3775290) and TLR4 (rs4986790) genotyping was done by PCR-restriction fragment length polymorphisms (PCR-RFLP), LFTs and AFP by standard routine techniques. Liver fibrosis was assessed clinically by the Fibrotest and Actitest.

RESULT

The TLR3 rs3775290 minor T genotype was linked with increased risk of chronic HBV (P = 0.05) and HCV (P = 0.031) infection. The TLR4 rs4986790 minor G genotype was linked with significantly increased risk for HBV/HCV chronic infection (P < 0.001). Subgroups analyses indicated decreased risk of HBV-related HCC in relation to TLR3 rs3775290 CC/CT genotype (P = 0.022), with increased risk ascribed to the minor (T) allele (P = 0.04). Likewise, TLR4 rs4985790 minor (GG) genotype was positively associated with HBV-linked HCC (P < 0.001). Furthermore, a link between TLR3 TT (P < 0.001) andTLR4 GG (P = 0.04) minor genotypes was noted in relation to increased risk of HCV-related disease.

CONCLUSION

TLR3 and TLR4 polymorphisms are promising biomarkers of liver cirrhosis and cancer associated with HBV and HCV infection.

Interleukin-6 and Tumor Growth Factor-β are Risk Factors for Idiopathic Epistaxis

Objective

To evaluate the serum levels of interleukin (IL)-6, IL-8, tumor necrosis factor (TNF)-α, tumor growth factor (TGF)-β, endothelin, and immunoglobulin (Ig)E in patients with idiopathic epistaxis, compared with healthy control individuals.

Methods

Serum levels of IL-6, IL-8, TNF-α, TGF-β, endothelin, and IgE were evaluated in 110 patients with idiopathic epistaxis and 100 healthy controls using the enzyme-linked immunosorbent assay (ELISA) technique.

Results

Serum levels of IL-6 (P <.001) and TGF-β (P = .001) were significantly increased in patients with idiopathic epistaxis, compared with controls. TNF-α serum levels were significantly increased in male patients, compared with female patients (P = .053). We observed decreased antihistamine levels and increased expression of TGF-β (P = .02) and TNF-α (P = .02), respectively.

Conclusions

IL-6 and TGF-β appear to participate in the pathogenesis of idiopathic epistaxis. TNF-α may be considered a risk factor for male patients in developing epistaxis. Antihistamines may inhibit angiogenesis by decreasing expression of TGF-β and increasing expression of TNF-α.

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.

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.

HCFC2 is needed for IRF1- and IRF2-dependent Tlr3 transcription and for survival during viral infections

Sun et al. show that host cell factor C2 (HCFC2) is necessary for basal and induced Tlr3 transcription; deficiency of HCFC2 compromises survival during influenza virus and herpes simplex virus 1 infections in mice.

Transcriptional regulation of numerous interferon-regulated genes, including Toll-like receptor 3 (Tlr3), which encodes an innate immune sensor of viral double-stranded RNA, depends on the interferon regulatory factor 1 (IRF1) and IRF2 transcription factors. We detected specific abrogation of macrophage responses to polyinosinic-polycytidylic acid (poly(I:C)) resulting from three independent N-ethyl-N-nitrosourea–induced mutations in host cell factor C2 (Hcfc2). Hcfc2 mutations compromised survival during influenza virus and herpes simplex virus 1 infections. HCFC2 promoted the binding of IRF1 and IRF2 to the Tlr3 promoter, without which inflammatory cytokine and type I IFN responses to the double-stranded RNA analogue poly(I:C) are reduced in mouse macrophages. HCFC2 was also necessary for the transcription of a large subset of other IRF2-dependent interferon-regulated genes. Deleterious mutations of Hcfc2 may therefore increase susceptibility to diverse infectious diseases.

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: 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.

Vitamin B12 in Association with Antipsychotic Drugs Can Modulate the Expression of Pro-/Anti-Inflammatory Cytokines in Alzheimer Disease Patients

INTRODUCTION

Patients with Alzheimer disease (AD) suffer from psychotic symptoms including pain. The current antipsychotic drugs confer limited effectiveness, and hence new strategies are being designed to decrease pain in order to increase antipsychological effectiveness. Vitamin B12 is a safe supplementary drug to decrease pain. Additionally, cytokines participate in the pathogenesis of immune-related diseases such as AD. Thus, the main aim of this clinical trial study was to determine the effects of treatment with risperidone and quetiapine, as antipsychotic drugs, with and without vitamin B12 on the psychotic symptoms of AD patients and the expression of IL-6, IL-8, tumor growth factor (TGF)-β, tumor necrosis factor (TNF)-α, and endothelin (ET)-1).

MATERIAL AND METHODS

Serum levels of IL-6, IL-8, TGF-β, TNF-α, and ET-1 were evaluated in the following groups: healthy controls, nonpsychotic AD patients, psychotic AD patients, psychotic AD patients under treatment with risperidone, psychotic AD patients under treatment with risperidone plus vitamin B12, psychotic AD patients under treatment with quetiapine, and psychotic AD patients under treatment with quetiapine plus vitamin B12.

RESULTS

Treatment with antipsychotic drugs plus vitamin B12 led to a decreased expression of IL-8 and TNF-α and an increased expression of TGF-β. Vitamin B12 in association with quetiapine reduced the pain in psychotic AD patients.

DISCUSSION

Proinflammatory cytokines play important roles in the pathogenesis of psychosis in AD patients. Antipsychotic drugs plus vitamin B12 can reduce and induce the expression of proinflammatory and anti-inflammatory cytokines to improve psychotic symptoms in AD patients.

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.

Hepatitis B virus genome replication triggers toll-like receptor 3-dependent interferon responses in the absence of hepatitis B surface antigen

The hepatitis B virus (HBV) has been described as stealth virus subverting immune responses initially upon infection. Impaired toll-like receptor signaling by the HBV surface antigen (HBsAg) attenuates immune responses to facilitate chronic infection. This implies that HBV replication may trigger host innate immune responses in the absence of HBsAg. Here we tested this hypothesis, using highly replicative transgenic mouse models. An HBV replication-dependent expression of antiviral genes was exclusively induced in HBsAg-deficient mice. These interferon responses attributed to toll-like receptor 3 (TLR3)-activated Kupffer and liver sinusoidal endothelial cells and further controlled the HBV genome replication. However, activation of TLR3 with exogenous ligands indicated additional HBs-independent immune evasion events. Our data demonstrate that in the absence of HBsAg, hepatic HBV replication leads to Tlr3-dependent interferon responses in non-parenchymal liver cells. We hypothesize that HBsAg is a major HBV-mediated evasion mechanism controlling endogenous antiviral responses in the liver. Eradication of HBsAg as a therapeutic goal might facilitate the induction of endogenous antiviral immune responses in patients chronically infected with HBV.

Investigation of 1377C/T polymorphism of the Toll-like receptor 3 among patients with chronic hepatitis B

The immunopathogenesis of chronic hepatitis B (CHB) has not been clarified yet. Toll-like receptors (TLR) are a receptor family that initiates immunity with exogenous-endogenous ligands and plays a role in the pathogenesis of infections. In this study, we aimed to investigate the frequency of TLR 3 1377C/T (rs3775290) polymorphism and its role in patients with CHB. We included 50 healthy individuals as control group and 73 active and 43 inactive hepatitis B patients. All DNA samples were isolated from blood samples. For the detection of TLR 3 1377C/T single-nucleotide polymorphism, restriction fragment length polymorphism was used. A statistically significant difference was determined in Hepatitis B virus (HBV) DNA levels of CHB patients with the CC, CT, and TT genotypes (p = 0.013). The highest levels of HBV DNA were detected in individuals with TT genotypes. Additionally, the frequency of CC genotype was higher in the active CHB patients compared with that of the inactive CHB patients (p = 0.044). No statistically significant difference in TLR 3 1377C/T polymorphism was detected between healthy controls and the hepatitis B patients (p = 0.342). In conclusion, HBV DNA level was higher in the individuals with TT genotype, and CC genotype was more frequent in the active CHB patients. These results suggest a possible association between CHB and TLR 3 gene (1377C/T) polymorphism.

Toll-like receptor 3 gene polymorphisms are not associated with the risk of hepatitis B and hepatitis C virus infection

INTRODUCTION

The present study investigated the prevalence of two single-nucleotide polymorphisms (SNPs) in the Toll-like receptor 3 (TLR3) gene in patients infected with hepatitis B virus (HBV) and hepatitis C virus (HCV).

METHODS

Samples collected from HCV (n = 74) and HBV (n = 35) carriers were subjected to quantitative real-time PCR (qPCR) to detect the presence of the SNPs rs5743305 and rs3775291 in TLR3 and to measure the following biomarkers: alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transpeptidase (GGT), and prothrombin time (PT). A healthy control group was investigated and consisted of 299 HCV- and HBV-seronegative individuals.

RESULTS

No significant differences in allele, genotype and haplotype frequencies were observed between the investigated groups, and no association was observed between the polymorphisms and histopathological results. Nevertheless, genotypes TA/AA (rs5743305) and GG (rs3775291) appear to be associated with higher levels of ALT (p<0.01), AST (p<0.05) and PT (p<0.05). In addition, genotypes TT (rs5743305; p<0.05) and GG (rs3775291; p<0.05) were associated with higher GGT levels.

CONCLUSIONS

This genetic analysis revealed the absence of an association between the polymorphisms investigated and susceptibility to HBV and HCV infection; however, these polymorphisms might be associated with a greater degree of biliary damage during the course of HCV infection.

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.

Are RIG-1 and MDA5 Expressions Associated with Chronic HBV Infection?

Melanoma differentiation-associated protein 5 (MDA5) and retinoic acid-inducible gene 1 (RIG-1) as the pattern recognition receptors play important roles in viral mRNA recognition. Chronic HBV-infected (CHB) patients are unable to properly respond to hepatitis B virus (HBV). Therefore, the aim of the present study was to evaluate the mRNA levels of MDA5 and RIG-1 in the peripheral blood immune cells of CHB patients in comparison to healthy controls. In this cross-sectional study, the mRNA levels of MDA5 and RIG-1 were examined in 60 CHB patients and 60 healthy controls using the real-time polymerase chain reaction (PCR) technique. Our results showed that mRNA levels of MDA5 and RIG-1 were significantly decreased and increased, respectively, in CHB patients when compared to healthy controls. Our results also revealed that mRNA levels of MDA5 and RIG-1 were not altered among CHB patients with various states of e-antigen of hepatitis B and HBV-DNA viral loads. According to the results presented here, it may be concluded that downregulation of MDA5 may be a responsible mechanism from several reasons, which leads to HBV persistence in CHB patients.

Regulation of TLR3 Activation by S100A9

Recognition of viral dsRNA by endosomal TLR3 activates innate immune response during virus infection. Trafficking of TLR3 to the endolysosomal compartment arising from fusion of late endosome (LE) with lysosome is required for recognition and detection of pathogen associated molecular patterns, which results in activation of the TLR3-dependent signaling cascade. Existing knowledge about the mechanism(s) and cellular factor(s) governing TLR3 trafficking is limited. In the current study, we identified intracellular S100A9 protein as a critical regulator of TLR3 trafficking. S100A9 was required for maturation of TLR3 containing early endosome (EE) into LE, the compartment that fuses with lysosome to form the endolysosomal compartment. A drastic reduction in cytokine production was observed in S100A9-knockout (KO) primary macrophages following RNA virus infection and treatment of cells with polyinosinic-polycytidylic acid (polyIC; a dsRNA mimetic that acts as a TLR3 agonist). Mechanistic studies revealed colocalization and interaction of S100A9 with TLR3 following polyIC treatment. S100A9-TLR3 interaction was critical for maturation of TLR3 containing EE into LE because TLR3 could not be detected in the LE of polyIC-treated S100A9-KO macrophages. Subsequently, TLR3 failed to colocalize with its agonist (i.e., biotin-labeled polyIC) in S100A9-deficient macrophages. The in vivo physiological role of S100A9 was evident from loss of cytokine production in polyIC-treated S100A9-KO mice. Thus, we identified intracellular S100A9 as a regulator of TLR3 signaling and demonstrated that S100A9 functions during pre-TLR3 activation stages by facilitating maturation of TLR3 containing EE into LE.

Innate immune evasion by hepatitis B virus-mediated downregulation of TRIF

Hepatocytes are the target host cells during hepatitis B virus (HBV) infection. Recent studies indicate that the innate immune response of hepatocytes plays an important role in inhibiting HBV replication. TIR-domain-containing adaptor inducing interferon-beta (TRIF) is a key component in innate immune signaling pathways. In this study, we found that the TRIF protein was downregulated in human hepatoma cell lines and liver tissue samples harboring HBV. Hepatitis B virus X protein (HBX) reduced TRIF protein expression in a dose-dependent manner via the proteasomal pathway. HBX appeared to not directly interact with TRIF as these proteins failed to co-immunoprecipitate when overexpressed in hepatoma cells. TRIF upregulation in hepatoma cell lines dramatically inhibited HBV transcription and expression of its viral proteins. Cellular apoptosis induced by TRIF was also confirmed in hepatoma cell lines. Taken together, these findings reveal a new mechanism for HBV evasion of the cellular innate immunity by HBX-mediated degradation of TRIF protein in hepatocytes.

TLR3 Plays Significant Roles against HBV-Associated HCC

Toll-like receptor 3 (TLR3) is a pattern-recognizing receptor that is involved in immune signaling and plays a crucial role in survival by being able to recognize various viral components including double-stranded RNA (dsRNA). The role of TLR3 in hepatocellular carcinoma (HCC) with hepatitis B virus (HBV) infections is not well understood. To investigate the ability of TLR3 in regulating HBV replication in HCC, 80 cases of human HCC were collected and their tissue microarray was made. In HCC cells, the expression and location of TLR3, hepatitis-associated virus, and interstitial immunoreactive cells were assayed with immunohistochemical staining. The apoptosis of tumor cells was also detected by TUNEL stain. Correlations between TLR3 expression and HBV infection, interstitial immunoreactive cells, and cells apoptosis in HCC were investigated. In addition, we explored whether TLR3 agonist dsRNA can inhibit HepG2.2.15 cells secreting HBV. We found that the cytoplasmic expression of TLR3 in HCC is positively related to HBsAg infection and HCC with cirrhosis and promotes interstitial immunoreactive cells infiltration and cancer cells apoptosis. In HepG2.2.15 cells, dsRNA inhibited the secretion of HBV and induced apoptosis. These results indicate that TLR3 signaling activity may be involved in immune responses against HBV in HCC.