Differential host responses to COVID-19: Unraveling the complexity

These diverse outcomes of Covid-19 are influenced by various factors including age, gender, underlying health conditions, immune responses, viral variants, external factors, and overall quality of life. Demographic analysis of patients aged 0-18 years experienced mild to moderate cases, above 55 years with co-morbidities, were more severely affected.COVID-19 incidence was higher in males (58 %) & (42 %) in females. The reduced expression of Toll-like receptors (TLR) in severe and critical patients is a crucial determinant. This reduced TLR expression is primarily attributed to the dominance of the PLpro viral protein of COVID-19. Disease enrichment analysis highlights the long-term impact of COVID-19, which can lead to post-recovery complications such as hypertension, diabetes, cardiac diseases, and brain ischemia in Covid-19 patients. In conclusion, a comprehensive strategy targeting key factors like PLpro, TLR, and inflammatory cytokines such as IL-1 and IL-6 could offer an effective approach to mitigate the devastating effects of COVID-19.

Porphyromonas gingivalis Lipopolysaccharide Damages Mucosal Barrier to Promote Gastritis-Associated Carcinogenesis

BACKGROUND

Recent epidemiological studies suggested correlation between gastric cancer (GC) and periodontal disease.

AIMS

We aim to clarify involvement of lipopolysaccharide of Porphyromonas gingivalis (Pg.), one of the red complex periodontal pathogens, in the GC development.

METHODS

To evaluate barrier function of background mucosa against the stimulations, we applied biopsy samples from 76 patients with GC using a Ussing chamber system (UCs). K19-Wnt1/C2mE transgenic (Gan) mice and human GC cell-lines ± THP1-derived macrophage was applied to investigate the role of Pg. lipopolysaccharide in inflammation-associated carcinogenesis.

RESULTS

In the UCs, Pg. lipopolysaccharide reduced the impedance of metaplastic and inflamed mucosa with increases in mRNA expression of toll-like receptor (TLR) 2, tumor necrosis factor (TNF) α, and apoptotic markers. In vitro, Pg. lipopolysaccharide promoted reactive oxidative stress (ROS)-related apoptosis as well as activated TLR2-β-catenin-signaling on MKN7, and it increased the TNFα production on macrophages, respectively. TNFα alone activated TLR2-β-catenin-signaling in MKN7, while it further increased ROS and TNFα in macrophages. Under coculture with macrophages isolated after stimulation with Pg. lipopolysaccharide, β-catenin-signaling in MKN7 was activated with an increase in supernatant TNFα concentration, both of which were decreased by adding a TNFα neutralization antibody into the supernatant. In Gan mice with 15-week oral administration of Pg. lipopolysaccharide, tumor enlargement with β-catenin-signaling activation were observed with an increase in TNFα with macrophage infiltration.

CONCLUSIONS

Local exposure of Pg. lipopolysaccharide may increase ROS on premalignant gastric mucosa to induce apoptosis-associated barrier dysfunction and to secrete TNFα from activated macrophages, and both stimulation of Pg. lipopolysaccharide and TNFα might activate TLR2-β-catenin-signaling in GC.

Innate immune responses to SARS-CoV-2

This chapter provides an overview of the innate immune response to SARS-CoV-2, focusing on the recognition, activation, and evasion strategies employed by the virus. The innate immune system plays a crucial role in the early defense against viral infections, and understanding its response to SARS-CoV-2 is essential for developing effective therapeutic approaches. The chapter begins by explaining the basics of the innate immune system, including its components and salient features. It discusses the various pattern recognition receptors involved in recognizing SARS-CoV-2, such as toll-like receptors, RIG-I-like receptors, NOD-like receptors, and other cytosolic sensors. The binding and entry of the virus into host cells and subsequent activation of innate immune cells, including neutrophils, monocytes, macrophages, dendritic cells, NK cells, and ILCs, are explored. Furthermore, the secretion of key cytokines and chemokines, including type I interferons, IL-6, IL-17, and TNF-alpha, is discussed as part of the innate immune response. The concept of PANoptosis, involving programmed cell death mechanisms, is introduced as a significant aspect of the response to SARS-CoV-2. The chapter also addresses the innate immune evasion strategies employed by SARS-CoV-2, which allow the virus to evade or subvert the host immune response, contributing to viral persistence. Understanding these strategies is crucial for developing targeted therapies against the virus.

Dimethyl itaconate selectively targets inflammatory and metabolic pathways in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) co-evolves with its own microenvironment where inflammatory stimuli including toll-like receptors (TLR) signaling can protect CLL cells from spontaneous and drug-induced apoptosis by upregulating IκBζ, an atypical co-transcription factor. To dissect IκBζ-centered signaling pathways, we performed a gene expression profile of primary leukemic cells expressing either high or low levels of IκBζ after stimulation, highlighting that IκBζ is not only an inflammatory gene but it may control metabolic rewiring of malignant cells thus pointing to a novel potential opportunity for therapy. We exploited the capacity of the dimethyl itaconate (DI), an anti-inflammatory electrophilic synthetic derivative of the metabolite Itaconate, to target IκBζ. CLL cells, murine leukemic splenocytes, and leukocytes from healthy donors were treated in vitro with DI that abolished metabolic activation and reduced cell viability of leukemic cells only, even in the presence of robust TLR prestimulation. RNA sequencing highlighted that in addition to the expected electrophilic stress signature observed after DI treatment, novel pathways emerged including the downregulation of distinct MHC class II complex genes. In conclusion, DI not only abrogated the proinflammatory effects of TLR stimulation but also targeted a specific metabolic vulnerability in CLL cells.

SARS-CoV-2 E protein induces Toll like receptor 2-mediated neonatal lung injury in a model of COVID-19 viremia that is rescued by the glucocorticoid ciclesonide

SARS-CoV-2 viremia is associated with increased acute lung injury (ALI) and mortality in children and adults. The mechanisms by which viral components in the circulation mediate ALI in COVID-19 remain unclear. We tested the hypothesis that the SARS-CoV-2 envelope (E) protein induces Toll like receptor (TLR) - mediated ALI and lung remodeling in a model of neonatal COVID-19. Neonatal C57BL6 mice given intraperitoneal E protein injections revealed a dose-dependent increase in lung cytokines (Il6, Tnfα, and Il1β) and canonical pro-inflammatory TLR signaling. Systemic E protein induced endothelial immune activation, immune cell influx, and TGFβ signaling and lung matrix remodeling inhibited alveolarization in the developing lung. E protein-mediated ALI and TGFβ signaling was repressed in Tlr2-/-, but not Tlr4-/- mice. A single does of E protein induced chronic alveolar remodeling as evidenced by decreased radial alveolar counts and mean linear intercepts. Ciclesonide, a synthetic glucocorticoid, inhibited E protein-induced pro-inflammatory TLR signaling and ALI. In vitro, E protein mediated inflammation and cell death was TLR2-dependent in human primary neonatal lung endothelial cells, and was rescued by ciclesonide. This study provides insight into the pathogenesis of ALI and alveolar remodeling with SARS-CoV-2 viremia in children, while revealing the efficacy of steroids.

Brucella abortus induces mast cell activation through TLR-2 and TLR-4

The Gram-negative bacteria Brucella abortus is a major cause of brucellosis in animals and humans. The host innate immune response to B. abortus is mainly associated with phagocytic cells such as dendritic cells, neutrophils, and macrophages. However, as mast cells naturally reside in the main bacterial entry sites they may be involved in bacterial recognition. At present, little is known about the role of mast cells during B. abortus infection. The role of the innate immune receptors TLR2 and TLR4 in activation of mast cells by B. abortus (strain RB51) infection was analyzed in this study. The results showed that B. abortus did not induce mast cell degranulation, but did induce the synthesis of the cytokines IL-1β, IL-6, TNF-α, CCL3, CCL4, and CCL5. Furthermore, B. abortus stimulated key cell signaling molecules involved in mast cell activation such as p38 and NF-κB. Blockade of the receptors TLR2 and TLR4 decreased TNF-α and IL-6 release by mast cells in response to B. abortus. Taken together, our results demonstrate that mast cells are activated by B. abortus and may play a role in inducing an inflammatory response during the initial phase of the infection.

The emerging roles of TLR and cGAS signaling in tumorigenesis and progression of ovarian cancer

Ovarian cancer is fatal to women and has a high mortality rate. Although on-going efforts are never stopped in identifying diagnostic and intervention strategies, the disease is so far unable to be well managed. The most important reason for this is the complexity of pathogenesis for OC, and therefore, uncovering the essential molecular biomarkers accompanied with OC progression takes the privilege for OC remission. Inflammation has been reported to participate in the initiation and progression of OC. Both microenvironmental and tumor cell intrinsic inflammatory signals contribute to the malignancy of OC. Inflammation responses can be triggered by various kinds of stimulus, including endogenous damages and exogenous pathogens, which are initially recognized and orchestrated by a series of innate immune system related receptors, especially Toll like receptors, and cyclic GMP-AMP synthase. In this review, we will discuss the roles of innate immune system related receptors, including TLRs and cGAS, and responses both intrinsic and exogenetic in the development and treatment of OC.

The therapeutic potential of targeting Toll like receptor pathway in breast cancer

The toll-like receptor (TLR) signaling pathway plays a key role in inducing immune responses and were shown to be expressed in immune cells and tumor cells, and is involved in the progression of several malignancies including breast cancer. These findings provide a proof of the concept of targeting this pathway as a potential therapeutic option in the treatment of breast cancer. Moreover, there is a growing body of data showing the activation of TLRs in the tumor microenvironment and its dual function as anti-tumoral (dendritic T and natural killer cells activation) or pro-tumoral activity (cell proliferation, and drug resistance). Several agents have been developed for targeting of this pathway and one of these inhibitors, called Bacillus Calmette-Guerin (an agonist of TLR2 and TLR4), is recently being approved by FDA for immunotherapy of bladder cancer. This review summarizes the current knowledge of the mechanisms of action of TLR pathways in the development/progression of cancer for a better management of this disease.

Gut microbiome dysbiosis in the setting of solid organ transplantation: What we have gleaned from human and animal studies

The human gut microbiome refers to all of the microorganisms present throughout the length of the gastrointestinal tract. Gut flora influence host metabolic and immune processes in myriad ways. They also play an important role in maturation and modulation of the immune system. Dysbiosis or a pathologic alteration in gut flora has been implicated in a number of diseases ranging from metabolic, autoimmune and degenerative. Whether dysbiosis has similar implications in organ transplant has been the focus of a number of pre-clinical and clinical studies. Researchers have observed significant microbiome changes after solid organ transplantation in humans that have been associated with clinical outcomes such as post-transplant urinary tract infections and diarrhea. In this article, we will discuss the available data regarding pathologic alterations in gut microbiome (dysbiosis) in solid organ transplant recipients as well as some of challenges in this field. We will also discuss animal studies focusing on mouse models of transplantation that shed light on the underlying mechanisms that explain these findings.

Immunotherapeutic role of cabazitaxel treatment in the activation of TLR3 signalling in metastatic castration-resistant prostate cancer in vitro

BACKGROUND

The activation of toll like receptors (TLR) potentially affect the inflammatory tumor microenvironment and thus is associated with tumor growth or inhibition. Cabazitaxel (CAB) has been effectively used for the treatment of metastatic castration-resistant prostate cancer (mCRPC). However, the immune regulatory role of CAB in the tumor microenvironment is not clear. In this context, we for the first time assessed the immunotherapeutic role of CAB in the TLR3 signalling following activation of Poly I:C in mCRPC cells.

METHODS AND RESULTS

The cytotoxic and apoptotic effects of CAB with the induction of Poly I:C were determined by WST-1, Annexin V, acridine orange, RT-PCR analysis, ELISA assay and immunofluorescence staining in DU-145 mCRPC and HUVEC control cells. Our findings showed that CAB treatment with Poly I:C significantly suppressed the proliferation of DU-145 cells through the induction of apoptosis and caspase activation. Additionally, higher concentration of CAB mediated the activation of TLR3 via increased cytoplasmic and nuclear expression of TLR3, TICAM-1 and IRF-3 in mCRPC cells.

CONCLUSIONS

Co-treatment of CAB and Poly I:C was more effective in mCRPC cells with less toxicity in control cells. However, further investigations are required to elucidate the molecular mechanisms of TLRs signalling upon CAB treatment at the molecular level to further validate the immunotherapeutic efficacy of CAB in mCRPC.

Toll like receptor (2 and 4) expression and cytokine release by human neutrophils during tuberculosis treatment-A longitudinal study

Host innate immune responses to tuberculosis are poorly explored. Recent findings emphasize the importance of innate cells in working against Mycobacterium tuberculosis, the etiologic agent of this deadly disease. In this study we have tried to learn the role of neutrophils in building up immunity against this pathogen during therapy. We isolated neutrophils from peripheral blood of healthy volunteers and pulmonary tuberculosis patients at different phases of their treatment and cultured them withtoll like receptor ligands overnight. Toll like receptor 2 and 4 expression on neutrophils was analyzed using flow cytometry. The supernatants were used to measure cytokines. We found that in tuberculosis patients, expression of TLR2, a proven receptor of Mycobacterium tuberculosis on neutrophils, was increased throughout the duration of therapy (measured at diagnosis, second month and sixth month of therapy). This demonstrates that TLR2 expression is altered as a result of treatment, but not TLR4. Also, the chemokines IL-8 and MIP1α showed a 'dip and raise' fashion as the therapy proceeded. Even though the increase in the pro-inflammatory cytokine secretion by neutrophils seen at the end of therapy is not as expected, it definitely increases our understanding on the function of these cells during TB disease and its resolution and opens new direction in neutrophil research.

Toll-Like Receptors in Stem/Progenitor Cells

One of the bridges that control the cross-talk between the innate and adaptive immune systems is toll-like receptors (TLRs). TLRs interact with molecules shared and maintained by the source pathogens, but also with endogenous molecules derived from injured tissues (damage/danger-associated molecular patterns - DAMPs). This is likely why some kinds of stem/progenitor cells (SCs) have been found to express TLRs. The role of TLRs in regulating basal motility, proliferation, processes of differentiation, self-renewal, and immunomodulation has been demonstrated in these cells. In this book chapter, we will discuss the many different functions assumed by the TLRs in SCs, pointing out that, depending on the context and the type of ligands they perceive, they may have different effects. In addition, the role of TLR in SC's response to specific tissue damage and in reparative processes will be addressed, as well as how the discovery of molecules mediating TLR signaling's differential function may be decisive for the development of new therapeutic strategies. Given the available studies on TLRs in SCs, the significance of TLRs in sensing an injury to stem/progenitor cells and evaluating their action and reparative activity, which depends on the circumstances, will be discussed here. It could also be possible that SCs used in therapy could theoretically be exposed to TLR ligands, which could modulate their in vivo therapeutic potential. In this context, we need to better understand the mechanisms of action of TLRs on SCs and learn how to regulate these receptors and their downstream pathways in a precise way in order to modulate SC proliferation, survival, migration, and differentiation in the pathological environment. In this way, cell therapy may be strengthened and made safer in the future.

Genetic variations of toll-like receptors: Impact on susceptibility, severity and prognosis of bacterial meningitis

Bacterial meningitis (BM) is a serious infectious disease of the central nervous system，which is mainly caused by Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae, Group B Streptococcus and Listeria monocytogenes. Throughout the world, BM has become one of the most lethal diseases that commonly occurs in children. Toll like receptors (TLRs) are one of the most important immune defense lines in infectious diseases, and play an essential role in host defense. Accumulating evidence shows that genetic variations in TLRs are associated with host responses in BM. This review aims to summarize the role of different TLRs and their genetic variations in the susceptibility, severity and prognosis of BM and discuss the identified risk factors for better treatment and improvement of the course and outcome of BM.

Landscape of toll-like receptors expression in tumor microenvironment of triple negative breast cancer (TNBC): Distinct roles of TLR4 and TLR8

TNBC is the most aggressive and hormone receptor-negative subtype of breast cancer with molecular heterogeneity in bulk tumors hindering effective treatment. Toll-like receptors (TLRs) have the potential to ignite diverse immune responses in the tumor microenvironment (TME). This encouraged us to screen their transcript expression in the publically available TCGA datasets. Reported molecular subtypes of TNBC may represent different TMEs and we observed differentially expressed TLRs (DETs) i.e. TLR3/4/6/8/9 have unique expression pattern in the TNBC subtypes, particularly in Immunomodulatory (IM) TNBC subtype. We then dissected expression of the DETs in immune and other components of the TME. TLR4 and TLR8 showed significant (p-value ≤ 0.05) negative partial correlation with tumor purity compared to other DETs. Interestingly, TLR4 and TLR8 expression showed a significant (adjusted p-value ≤ 0.05) correlation with different subsets of immune infiltrating cells having the highest correlation with monocytes/macrophage/dendritic cell populations mediating both innate and adaptive response in TNBC. The co-expression network identified genes correlated with these immune cells. Further, GSEA analysis of co-expressed genes showed a significant association of TLR8 partners with 'Peptide ligand binding', 'Gά-signaling', and 'Cytokine-cytokine interaction' while TLR4 associated genes correlated with 'Adaptive immune system' and 'Systemic lupus erythematosus' interactome. Finally, the expression of TLR4 protein was validated in a panel of TNBC cell lines. TLR4 expression in chemoresponsive TNBC was also validated in TNBC cell lines upon Paclitaxel (PTX) treatment. Collectively, the present study identified specific DETs in TNBC and discovered a prospective role of TLR4 and TLR8 in the maintenance of tumor-immune-microenvironment.

Mechanistic understanding of innate and adaptive immune responses in SARS-CoV-2 infection

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections have triggered global pandemic that continue to impact adversely human health. New understanding has emerged about the innate and adaptive immune responses elicited in SARS-CoV-2 infection. The understanding of innate immune responses generated in hosts early in SARS-CoV-2 infection is vital for treatment efforts. Antiviral cytokines are released by innate immune cells in response to viral infections that play a pivotal role in limiting viral replication, pathology and generating optimal adaptive immune responses alongside the long-term memory responses against reinfections. One aspect of innate immune response generated against SARS-CoV-2 in vivo and which has received much attention has been high proinflammatory cytokine release in COVID-19 patients. Another vital discovery has been that the antiviral cytokine type I Interferon (IFN) family IFN-α mediates upregulation of angiotensin converting enzyme 2 (ACE2) membrane protein in airway epithelial cells. ACE2 is a receptor that SARS-CoV-2 binds to infect host cells. New understanding has emerged about the mechanism of SARS-CoV-2 induced exaggerated proinflammatory cytokine release as well as transcriptional regulation of ACE2. This review discusses various mechanisms underlying SARS-CoV-2 induced exaggerated proinflammatory cytokine response as well as transcriptional regulation of ACE2 receptor. We further elaborate on adaptive and memory responses generated against SARS-CoV-2.

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.

Encapsulation of a CpG oligonucleotide in cationic liposomes enhances its local antitumor activity following pulmonary delivery in a murine model of metastatic lung cancer

Immunotherapy brings new hope to the fight against lung cancer. General immunostimulatory agents represent an immunotherapy strategy that has demonstrated efficacy with limited toxicity when delivered intratumorally. The goal of this study was to enhance the antitumor efficacy of unmethylated oligodeoxynucleotides containing CpG motifs (CpG) and polyinosinic-polycytidylic acid (poly I:C) double-stranded RNA following their local delivery in lung cancer by encapsulating them in liposomes. Liposomes encapsulation of nucleic acids could increase their uptake by lung phagocytes and thereby the activation of toll-like receptors within endosomes. Liposomes were prepared using a cationic lipid, dioleoyltrimethylammoniumpropane (DOTAP), and dipalmitoylphosphatidylcholine (DPPC), the main phospholipid in lung surfactant. The liposomes permanently entrapped CpG but could not efficiently withhold poly I:C. Both poly I:C and CpG delayed tumor growth in the murine B16F10 model of metastatic lung cancer. However, only CpG increased IFN-γ levels in the lungs. Pulmonary administration of CpG was superior to its intraperitoneal injection to slow the growth of lung metastases and to induce the production of granzyme B, a pro-apoptotic protein, and IFNγ, MIG and RANTES, T helper type 1 cytokines and chemokines, in the lungs. These antitumor activities of CpG were strongly enhanced by CpG encapsulation in DOTAP/DPPC liposomes. Delivery of low CpG doses to the lungs induced increased inflammation markers in the airspaces but the inflammation did not reach the systemic compartment in a significant manner. These data support the use of a delivery carrier to strengthen CpG antitumor activity following its pulmonary delivery in lung cancer.

Endoplasmic reticulum stress exacerbates inflammation in chronic rhinosinusitis with nasal polyps via the transcription factor XBP1

Endoplasmic reticulum (ER) stress results in the activation of the unfolded protein response (UPR), a process that is involved in the pathogenesis of many inflammatory diseases. However, the role of ER stress in chronic rhinosinusitis with nasal polyps (CRSwNP) has yet to be elucidated. In this study, we found that the protein expression levels of a range of ER stress regulators, including p-PERK, ATF4, ATF6 and XBP1s, were significantly increased in CRSwNP compared to controls. Importantly, the expression of ATF4 and XBP1s was positively correlated with heightened inflammation in CRSwNP. In human nasal epithelial cells, the ER stress inducer tunicamycin (TM) could potentiate Toll-like receptors (TLRs) induced proinflammatory cytokines production. Furthermore, we found that the silencing of XBP1, but not ATF4 or ATF6, abrogated the proinflammatory effect of TM. Mechanistically, ER stress did not affect the NF-κB, MAPK or IRF3 signaling pathways. However, the ER stress regulator XBP1s was able to bind directly to the promoter region of inflammatory genes to modulate gene transcription. Besides, the commensal bacteria Staphylococcus aureus and several inflammatory factors, such as IL4, IL13, IL17 and IFNγ, could induce ER stress in epithelial cells. Collectively, ER stress plays a crucial role in facilitating TLR-induced inflammation. Targeting XBP1 can inhibit the inflammatory response, thus offering a potential approach to treat CRSwNP.

Differential toll like receptor expression in cystic fibrosis patients' airways during rhinovirus infection

OBJECTIVES

Since an inappropriate and sustained activation of TLRs may contribute to a chronic inflammatory response resulting in detrimental effects in cystic fibrosis (CF) patients, we sought to examine whether HRV infection might alter the respiratory expression of TLRs according to the microbiological status of CF patients.

METHODS

Respiratory samples were collected from the respiratory tract of CF patients (n = 294) over a period of 12 months. In addition to the usual microbiological investigation, HRV-RNA detection and typing were performed by RT-PCR and sequencing. HRV viral load and TLRs levels were measured by RT-Real Time PCR.

RESULTS

HRV-RNA was detected in 80 out of 515 respiratory samples (15.5%) with a similar rate in all age groups (0-10 years, 11-24 years, ≥ 25 years). Patients infected with different HRV A, B and C species exhibited higher levels of TLR2, TLR4 and TLR8 as compared to HRV negative patients. Moreover, the expression level of TLR2, TLR4 and TLR8 correlated with high level of HRV viral load. HRV positive patients co-colonized by Staphylococcus aureus or Pseudomonas aeruginosa showed also enhanced amounts of TLR2 and TLR2/4-mRNAs expression respectively. In the case of presence of both bacteria, TLR2, TLR4, TLR8 and TLR9 levels are elevated in positive HRV patients.

CONCLUSIONS

TLRs, especially TLR2 and TLR4, increased in HRV positive CF individuals and varies according to the presence of S. aureus, P. aeruginosa and both bacteria.

Interrelationship between Toll-like receptors and infection after orthotopic liver transplantation

Early microbial recognition by the innate immune system is accomplished by Toll-like receptors (TLRs), with resultant initiation of a pro-inflammatory response against infecting organisms. In spite of presence of an abundance of Toll-like receptors on the surface of the liver, gut bacteria does not elicit an inflammatory reaction in healthy individuals due to tolerance to these TLRs, suggesting that the inflammatory responses seen in the liver are the result of breakdown of this tolerance. While orthotopic liver transplantation is often life saving in many instances, death following this procedure is most commonly due to infection that occurs in up to 80% of transplant recipients, most commonly due to microbial causes in up to 70% of cases and viral infections in 20%, while fungal infections affect only 8% of cases. The probability of acquiring infection following hepatic transplantation is heightened due to affection of the innate immune defense mechanisms of the host following this procedure. Single nucleotide polymorphisms of TLRs have been associated with increased likelihood of either development of post-transplant infection or eradication of infecting organism. However, conflicting reports from other studies reveal that prevalence of this single nucleotide polymorphism is not increased in infected patients.

Sargassum horneri (Turner) inhibit urban particulate matter-induced inflammation in MH-S lung macrophages via blocking TLRs mediated NF-κB and MAPK activation

ETHNOPHARMACOLOGICAL RELEVANCE

Sargassum horneri is a nutrient rich edible brown seaweed with numerous biological properties found in shallow coastal areas of Korean peninsula. S. horneri traditionally used as a medicinal ingredient to treat several disease conditions such as hyperlipidemia, hypertension, heart disease, and inflammatory diseases (furuncle). However, to utilize S. horneri as an active ingredient for functional foods and human health applications requires to conform the bioactive properties and underlying mechanisms of those activities.

AIM OF THE STUDY

Here, we investigated anti-inflammatory mechanisms of commercial grade 70% ethanol extract separated from S. horneri (SHE) on inflammatory response in particulate matter (PM)-induced MH-S lung macrophages; where PM in breathable air one of the major health concern in Korea.

MATERIALS AND METHODS

We compared the anti-inflammatory effects of SHE on the activity of toll-like receptors (TLR) activation, NF-κB, MAPKs, and pro-inflammatory cytokine secretion in MH-S lung macrophages exposed to PM as a lung inflammation model.

RESULTS

According to the results, PM-stimulation, induced the levels of NO, PGE2, TNF-α, IL-1β, IL-6, iNOS, and COX2 (P < 0.05) in MH-S macrophages. In addition, phosphorylation levels of NF-κB and MAPKs were also increased with the PM stimulation through the upregulated expression of TLR. However, SHE treatment significantly repressed the secretions of inflammatory cytokines and reduced protein expression such as PGE2, TNF-α, IL-6, IL-1β, NF-κB, and MAPKs from PM-activated macrophages. Specifically, SHE inhibited the upregulated mRNA expression levels of TLR2, TLR3, TLR4, and TLR7 in PM-induced MH-S cells; known biomarkers of downstream activation of NF-κB and MAPKs.

CONCLUSION

These results suggested that SHE is a potential inhibitor of PM-induced inflammatory responses in lung macrophages. Thus, SHE could inhibit PM-induced chronic inflammation in lungs via blocking TLR/NF-κB/MAPKs signal transduction. Therefore, it was concluded that SHE may be a useful substance to develop as functional product to reduce inflammation against PM-induced inflammation.

Patients with enthesitis related arthritis show similar monocyte function pattern as seen in adult axial spondyloarthropathy

BACKGROUND

Axial SpA and Enthesitis related arthritis (ERA) patients show strong HLA-B27 association, gut dysbiosis, high toll like receptor (TLR)2 and 4 expression on monocytes, pro-inflammatory cytokine production and elevated levels of TLR4 endogenous ligands [tenascin-c (TNC) and myeloid related protein (MRP)8/14] in serum. Hence, we aimed to understand if these diseases have similar or different monocyte response.

METHODS

Fifty adult axial SpA, 52 ERA patients and 25 healthy controls (HC) were enrolled. Cytokine-producing monocyte frequency before and after stimulation with lipopolysaccharide (LPS), peptidoglycan (PG), TNC or MRP8 were measured in whole blood (WB) and synovial fluid mononuclear cells (SFMC) by flow cytometry. Also, IL-6, TNF, MMP3, TNC and MRP8/14 levels were measured in unstimulated and TLR ligand stimulated WB cultures supernatant by ELISA. Finally, the mRNA expression levels of TNF and IL-6 were measured post stimulation with LPS, TNC and MRP8.

RESULTS

At baseline, ERA and axial SpA patients showed similar TNF-α producing monocyte frequency which was higher than HC. MRP8 simulation led to increased TNF-α producing monocyte frequency in ERA than axial SpA. TNC and MRP8 stimulation led to similar IL-6 producing monocyte frequency in axial SpA and ERA patients. Baseline TNF and IL-6 producing monocyte frequency also modestly correlated with disease activity scores. TNF and IL-6 producing monocyte frequency increased in response to TLR stimulation in SFMC from both patients. In culture supernatants, axial SpA and ERA patients showed similar TNF production at baseline. MRP8 and TNC stimulation led to higher TNF production from ERA. Baseline IL-6 and MMP3 production was higher in ERA while TLR stimulation led to similar IL-6 and MMP3 production from axial SpA and ERA. TNC stimulation led to higher MMP3 production in ERA. mRNA expression in response to TLR stimulation was observed to be similar in axial SpA and ERA. TNC production was higher in ERA at baseline, while MRP8/14 production was higher in axial SpA than ERA post stimulation.

CONCLUSION

ERA patients have similar monocyte response to exogenous and endogenous TLR ligands as patients with axial SpA. This suggests that differences between pediatric and adult-onset SpA are minimal and they may have a common pathogenesis.

The role of the innate immune system on pulmonary infections

Inhalation is required for respiration and life in all vertebrates. This process is not without risk, as it potentially exposes the host to environmental pathogens with every breath. This makes the upper respiratory tract one of the most common routes of infection and one of the leading causes of morbidity and mortality in the world. To combat this, the lung relies on the innate immune defenses. In contrast to the adaptive immune system, the innate immune system does not require sensitization, previous exposure or priming to attack foreign particles. In the lung, the innate immune response starts with the epithelial barrier and mucus production and is reinforced by phagocytic cells and T cells. These cells are vital for the production of cytokines, chemokines and anti-microbial peptides that are critical for clearance of infectious agents. In this review, we discuss all aspects of the innate immune response, with a special emphasis on ways to target aspects of the immune response to combat antibiotic resistant bacteria.

Differential expression patterns of Toll Like Receptors and Interleukin-37 between calcific aortic and mitral valve cusps in humans

BACKGROUND

Significant differences are mentioned in the progress of calcification between aortic and mitral valve. Evidence of inflammation in calcific aortic and mitral valve disease suggests that pathways of Toll Like Receptors (TLR) and Interleukin (IL)-37 expression may contribute to this process. We sought to investigate the role of TLR-mediated inflammatory response and IL-37 pathway expression on aortic and mitral valve calcification.

MATERIAL AND METHODS

One-hundred twenty stenotic valve cusps/leaflets (60 aortic, 60 mitral) were excised during surgery and were collected for histological, immunohistochemistry and morphometric analysis at our department. After total RNA isolation from a second part of valve cusps/leaflets, cDNA synthesis and quantitative reverse transcription polymerase chain reaction (qRT-PCR) protocols were performed and relative mRNA levels of target genes were assessed.

RESULTS

By histological analysis, the anti-inflammatory IL-37 levels were increased in mitral valve leaflets (MVL) compared to aortic valve cusps (AVCu) while all other biomarkers, including TLR, presented a reverse pattern with decreased levels as compared to AVCu. In terms of calcification biomarkers, only osteopontin differed between AVCu and MVL. mRNA analysis confirmed increased expression of IL-37 and decreased levels of TLR in MVL compared to AVCu.

CONCLUSIONS

Stenotic cusps of aortic valves express lower IL-37 and increased TLRs levels than stenotic mitral valve leaflets, suggesting a differential pro-calcification and pro-inflammatory profile between the two valves. This may explain the higher incidence of calcification of AVCu than MVL and offer therapeutic considerations.

Broiler gut microbiota and expressions of gut barrier genes affected by cereal type and phytogenic inclusion

The present study assessed the effects of cereal type and the inclusion level of a phytogenic feed additive (PFA) on broiler ileal and cecal gut microbiota composition, volatile fatty acids (VFA) and gene expression of toll like receptors (TLR), tight junction proteins, mucin 2 (MUC2) and secretory immunoglobulin A (sIgA). Depending on cereal type (i.e. maize or wheat) and PFA inclusion level (i.e. 0, 100 and 150 mg/kg diet), 450 one-day-old male broilers were allocated in 6 treatments according to a 2 × 3 factorial arrangement with 5 replicates of 15 broilers each, for 42 d. Significant interactions (P ≤ 0.05) between cereal type and PFA were shown for cecal digesta Bacteroides and Clostridium cluster XIVa, ileal digesta propionic and branched VFA, ileal sIgA gene expression, as well as cecal digesta branched and other VFA molar ratios. Cereal type affected the cecal microbiota composition. In particular, wheat-fed broilers had higher levels of mucosa-associated Lactobacillus (P _CT = 0.007) and digesta Bifidobacterium (P _CT < 0.001), as well as lower levels of total bacteria (P _CT = 0.004) and Clostridia clusters I, IV and XIVa (P _CT ≤ 0.05), compared with maize-fed ones. In addition, cereal type gave differences in fermentation intensity (P _CT = 0.021) and in certain individual VFA molar ratios. Wheat-fed broilers had higher (P ≤ 0.05) ileal zonula occluden 2 (ZO-2) and lower ileal and cecal TLR2 and sIgA levels, compared with maize-fed broilers. On the other hand, PFA inclusion at 150 mg/kg had a stimulating effect on microbial fermentation at ileum and a retarding effect in ceca with additional variable VFA molar patterns. In addition, PFA inclusion at 100 mg/kg increased the ileal mucosa expression of claudin 5 (CLDN5) (P _PFA = 0.023) and MUC2 (P _PFA = 0.001) genes, and at 150 mg/kg decreased cecal TLR2 (P _PFA = 0.022) gene expression compared with the un-supplemented controls. In conclusion, cereal type and PFA affected in combination and independently broiler gut microbiota composition and metabolic activity as well as the expression of critical gut barrier genes including TLR2. Further exploitation of these properties in cases of stressor challenges is warranted.

Sequence and functional variability of Toll-like receptor 9 gene in equines

Significant structural differences in the extracellular domain of toll-like receptor 9 (TLR9) account for species-specific recognition of its ligand CpG-ODN sequences. TLR9 is extensively studied in human, mice and some domestic animals. The recognition ability appears to be utilized differently by various species and breeds, but so far no comprehensive study exists about the equine TLR9 gene. We characterized TLR9 sequences of Marwari and Zanskari breeds of horses and Poitu donkey. We sequenced and identified the protein coding regions of equine TLR9 and compared with other animals and human beings. Furthermore, we also analyzed the amino acid substitutions and their likely implications on functions. The analysis revealed 14% evolutionary divergence between equine and human TLR9, while it was 1% between the Equus caballus and Equus asinus and less than 1% within Equus caballus. In phylogenetic analysis of predicted amino acids, the indigenous equines grouped with thoroughbred Equus caballus, while human, cattle, dog, sheep, mice, and buffalo formed separate clades. Furthermore, we also analyzed the amino acid substitutions and their likely implications on functions by sorting intolerant from tolerant (SIFT) analysis and predicted two substitutions of amino acids (D80N and S822P) in Marwari horses in leucine rich repeat 1 (LRR1) without any functional effects. The substitutions (V214A and Y579C) in LRR 3 and LRR11 in Zanskari horses were predicted to have functional consequences. Out of overall 8 substitutions, three substitutions (I420V, S970R and R1001C) were found in Equus asinus in LRR7, LRR 13, and toll interleukin receptor (TIR) domains, while the substitution G649S is observed in Poitu donkey only. We report for the first time that despite the conserved residues, the striking effect of substitutions, found within the TLR9 genes of different equine breeds/species may have possible implications.

Innate and adaptive stimulation of murine diverse NKT cells result in distinct cellular responses

Natural killer T (NKT) cells recognize glycolipids presented on CD1d. They share features of adaptive T lymphocytes and innate NK cells, and mediate immunoregulatory functions via rapid production of cytokines. Invariant (iNKT) and diverse (dNKT) NKT cell subsets are defined by their TCR. The immunological role of dNKT cells, that do not express the invariant TCRα‐chain used by iNKT cells, is less well explored than that of iNKT cells. Here, we investigated signals driving Toll‐like receptor (TLR) ligand activation of TCR‐transgenic murine dNKT cells. IFN‐γ production by dNKT cells required dendritic cells (DC), cell‐to‐cell contact and presence of TLR ligands. TLR‐stimulated DC activated dNKT cells to secrete IFN‐γ in a CD1d‐, CD80/86‐ and type I IFN‐independent manner. In contrast, a requirement for IL‐12p40, and a TLR ligand‐selective dependence on IL‐18 or IL‐15 was observed. TLR ligand/DC stimulation provoked early secretion of pro‐inflammatory cytokines by both CD62L⁺ and CD62L⁻ dNKT cells. However, proliferation was limited. In contrast, TCR/co‐receptor‐mediated activation resulted in proliferation and delayed production of a broader cytokine spectrum preferentially in CD62L⁻ dNKT cells. Thus, innate (TLR ligand/DC) and adaptive (TCR/co‐receptor) stimulation of dNKT cells resulted in distinct cellular responses that may contribute differently to the formation of immune memory.

Differential expression of TLRs 2, 4, 9, iNOS and TNF-α and arginase activity in peripheral blood monocytes from glucantime unresponsive and responsive patients with anthroponotic cutaneous leishmaniasis caused by Leishmania tropica

BACKGROUND

Detection of the mechanism of host/parasite interactions in unresponsive forms of anthroponotic cutaneous leishmaniasis (ACL) caused by Leishmania tropica is helpful for immunotherapy and vaccine development. In the present study, the gene expression of toll-like receptors (TLRs), TNF-α, iNOS and also arginase (ARG) activity in monocytes from Glucantime unresponsive in comparison to responsive patients infected with L. tropica was investigated.

METHODS

In this case-control study, patients with unresponsive (n = 10) and responsive (n = 10) ACL were recruited. Gene expression of TLR2, TLR4, TLR9, TNF-α and iNOS was analyzed in L. tropica-exposed monocytes. The level of ARG activity in both isolated promastigotes and the lysates of monocytes was also determined.

RESULTS

L. tropica-exposed monocytes represented higher expression of all three TLRs and TNF-α and lower expression of iNOS compared to unexposed ones in both groups of patients. Results revealed a significant down-regulation of TLR2 and TNF-α and up-regulation of TLR9 expression in unresponsive isolates in comparison to responsive ones. Besides, ARG level showed a significant increase in L. tropica-stimulated monocytes and cultured promastigotes from unresponsive isolates versus responsive ones.

CONCLUSIONS

The decreased TLR2, TLR4, TNF-α and iNOS and the increased level of TLR9 expression in L. tropica-exposed monocytes from unresponsive isolates and also the increment in ARG activity in their promastigotes and monocytes, might possibly be involved in the severity of the disease and leading to Glucantime unresponsiveness.

Isolation, identification and characterization of apigenin from Justicia gendarussa and its anti-inflammatory activity

Inflammatory responses during chronic diseases such as atherosclerosis, cancer etc., are harmful to host organisms. Generally NSAIDs are used to treat against these severe conditions but due to its adverse effects studies are going on with medicinal plants, since they are rich in bioactive compounds. Justicia gendarussa is one such plant which has been used as a remedial measure for treating inflammatory diseases since ancient time. Thus the present study involved in the isolation, characterization and identification of apigenin (flavonoid) from this plant and to elucidate its molecular mechanism against inflammation via TLR-NF-κB signaling pathway using ox-LDL induced hPBMCs in in vitro model. Methanolic extract was used for the isolation process and results showed that the F6 fraction collected from ethyl acetate through column chromatography showed 89% paw edema inhibition at a dose of 10 mg/kg in carrageenan induced rats. Purification of F6 by TLC with toluene: chloroform: acetone (8:5:7) and further characterization by ¹HNMR indicated the presence of bioactive compound, apigenin. In vitro studies revealed that pretreatment of ox-LDL induced hPBMCs with apigenin (25 μM) significantly (P < 0.05) reduced the levels of TLR4, MyD88, TRIF, TRAF6, NF-κB, COX-2, PGE2, IL-1β and TNF-α responsible for generating inflammation and elevated the level of anti-inflammatory cytokine, IL-10. These results indicate the therapeutic efficacy of bioflavonoid apigenin which was isolated from Justicia gendarussa against ox-LDL induced inflammation. Therefore apigenin can be treated as a suitable therapeutic agent against inflammatory diseases.

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.

Elevated intragraft expression of innate immunity and cell death-related markers is a risk factor for adverse graft outcome

BACKGROUND

Molecules of the innate immune response are increasingly recognized as important mediators in allograft injury during and after kidney transplantation. We therefore aimed to establish the relationship between the expression of these genes at implantation, during an acute rejection (AR) and on graft outcome.

METHODS

A total of 19 genes, including Toll like receptors (TLRs), complement components and regulators, and apoptosis-related genes were analyzed at the mRNA level by qPCR in 123 biopsies with acute rejection and paired pre-transplantation tissue (n = 75).

RESULTS

Before transplantation, relative mRNA expression of BAX:BCL2 ratio (apoptosis marker) and several complement genes was significantly higher in tissue samples from deceased donors compared to living donors. During AR, TLRs and complement genes showed an increased expression compared to pre-transplant conditions, whereas complement regulators were decreased. A relatively high TLR4 expression level and BAX:BCL2 ratio during AR in the deceased donor group was associated with adverse graft outcome, independently of clinical risk factors.

CONCLUSIONS

Complement- and apoptosis-related gene expression is elevated in deceased donor transplants before transplantation. High BAX:BCL2 ratio and TLR4 expression during AR may reflect enhanced intragraft cell death and immunogenic danger signals, and pose a risk factor for adverse graft outcome.

Chronic kidney disease induces inflammation by increasing Toll-like receptor-4, cytokine and cathelicidin expression in neutrophils and monocytes

TLR expression in neutrophils and monocytes is associated with increased cytokine synthesis, resulting in increased inflammation. However, the inflammatory pathway related to TLR and cathelicidin expression in these cells from CKD patients is unclear. To evaluate TLR4, cathelicidin, TNF-α, IL-6, IL-10 and MCP-1 expression in neutrophils and monocytes from HD and CKD patients. Blood samples were drawn from 47 CKD and 43 HD patients and 71 age and gender-matched healthy volunteers (CONT). TLR4 was analyzed using flow cytometry. Cathelicidin, TNF-α, IL-6, IL-10 and MCP-1 were analyzed via ELISA.TLR4 expression in neutrophils was higher in HD patients than in stage 3 and 4 CKD patients. In these cells, we observed a positive correlation between TLR4 and cathelicidin, TNF-α, IL-6, IL-10 and MCP-1 levels. In monocytes, TLR4 expression was significantly higher in CKD 3 and 4 groups than in the control and HD groups and positively and negatively correlated with IL-6 and MCP-1 and cathelicidin, respectively. TNF-α, IL-6 and MCP-1 serum levels were higher in HD and CKD patients than in control. Cathelicidin and IL-10 levels were only higher in HD patients. IL-6 serum levels were positively correlated with all cytokines, and cathelicidin was negatively correlated with MCP-1 (r = - 0.35; p < 0.01) and positively correlated with IL-10 (r = 0.37; p = 0.001). These results suggest that a uremic environment induces high TLR4, cathelicidin and cytokine expression and may increase inflammation. Thus, future studies should be conducted to evaluate whether TLR4 and cathelicidin should be targets for anti-inflammatory therapeutic strategies.

Expression patterns of Toll like receptor (TLR)-2, TLR-4 and myeloid differentiation primary response gene 88 (MYD88) in renal transplant patients developing allograft dysfunction; a cohort study

This cohort intends to determine the sequential dynamic changes in Toll-like receptor (TLR)-4, TLR-2, and myeloid differentiation primary response gene 88 (MYD88) mRNA expressions in PBMCs and biopsy samples from kidney allograft recipients in relation to graft function. This study enrolled 52 renal transplant patients, 27 with well functioning graft (WFG) and 25 graft dysfunction (GD). Peripheral blood samples pre- and post-transplantation (days 2, 90 and 180) were collected to analyze mRNA expression levels of TLR-2, TLR-4, and MYD88 genes in relation to allograft function during one-year follow up. The mean dynamic changes of post-transplant TLR-2, TLR-4, and MYD88 mRNA expressions were significantly higher in GD compared to WFG patients (P = .001). ROC curve analysis based on glomerular filtration rate (GFR) index showed the area under curve (AUC) values for the genes: TLR-2(0.89;P < .001), TLR-4(0.86;P < .001), and MYD88(0.75;P = .003) in the third month post-transplantation for GD diagnosis. The calculated AUCs for the expressions of genes in allograft biopsies were 0.94(TLR-2), 0.95(TLR-4), and 0.98(MYD88) in the sixth month post-transplant based on pathology report (P < .001). Our results indicate that sequential monitoring of the expression patterns of TLR-2, TLR-4, and MYD88 in PBMCs and biopsy samples could be considered as predictive biomarkers for early and late kidney allograft function.

Transcriptional modulation of pattern recognition receptors in chronic colitis in mice is accompanied with Th1 and Th17 response

Pattern recognition receptors (PRRs) may contribute to inflammatory bowel diseases (IBD) development due to their microbial-sensing ability and the unique microenvironment in the inflamed gut. In this study, the PRR mRNA expression profile together with T cell-associated factors in the colon was examined using a chronic colitis mice model. 8–12 week old C57BL/6 mice were exposed to multiple dextran sodium sulfate (DSS) treatments interspersed with a rest period to mimic the course of chronic colitis. The clinical features and histological data were collected. The mRNA expressions of colonic PRRs, T cell-associated components were measured. Finally, the colons were scored for Foxp3+ cells. During chronic colitis, the histological data, but not the clinical manifestations demonstrated characteristic inflammatory symptoms in the distal colon. In contrast to acute colitis, the expression of all Toll-like receptors (Tlrs), except Tlr5 and Tlr9, was unaffected after repeated DSS treatments. The expression of Nod1 was decreased, while Nod2 increased. After third DSS treatment, only the expressions of Tlr3 and Tlr4 were significantly enhanced. Unlike other PRRs, decreased Tlr5 and increased Tlr9 mRNA expression persisted during the chronic colitis period. As the colitis progress, only the mRNA expression of Ifnγ and Il17 staid increased during chronic colitis, while the acute colitis-associated increase of Il23, and Il10 and Il12 was abolished. Finally, increased histological score of Foxp3+ cell in colon was found during the chronic colitis period. This study provides an expression pattern of PRRs during chronic colitis that is accompanied by a Th1- and Th17 cell-mediated immune response.

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This study provides an extensive survey of PRRs in the colon during chronic DSS-induced colitis.

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Chronic DSS colitis upregulates the mRNA expression of Tlr3, Tlr4, Tlr9 and Nod2.

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As the DSS colitis progresses to a chronic status the expression of Tlr5 decreases.

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The chronic DSS colitis results in a (progressive) increase of Th1 and Th17 cells.

Deposition and hydrolysis of serine dipeptide lipids of Bacteroidetes bacteria in human arteries: relationship to atherosclerosis

Multiple reaction monitoring-MS analysis of lipid extracts from human carotid endarterectomy and carotid artery samples from young individuals consistently demonstrated the presence of bacterial serine dipeptide lipid classes, including Lipid 654, an agonist for human and mouse Toll-like receptor (TLR)2, and Lipid 430, the deacylated product of Lipid 654. The relative levels of Lipid 654 and Lipid 430 were also determined in common oral and intestinal bacteria from the phylum Bacteroidetes and human serum and brain samples from healthy adults. The median Lipid 430/Lipid 654 ratio observed in carotid endarterectomy samples was significantly higher than the median ratio in lipid extracts of common oral and intestinal Bacteroidetes bacteria, and serum and brain samples from healthy subjects. More importantly, the median Lipid 430/Lipid 654 ratio was significantly elevated in carotid endarterectomies when compared with control artery samples. Our results indicate that deacylation of Lipid 654 to Lipid 430 likely occurs in diseased artery walls due to phospholipase A2 enzyme activity. These results suggest that commensal Bacteriodetes bacteria of the gut and the oral cavity may contribute to the pathogenesis of TLR2-dependent atherosclerosis through serine dipeptide lipid deposition and metabolism in artery walls.

The inhibitory receptor toll interleukin-1R 8 (TIR8/IL-1R8/SIGIRR) is downregulated in chronic lymphocytic leukemia

Toll interleukin-1 receptor 8 (also known as TIR8, SIGIRR, or IL1R8) is a transmembrane receptor that inhibits inflammation. Accordingly, genetic inactivation of this protein exacerbates chronic inflammation and inflammation-associated tumors in mice. In particular, lack of TIR8 triggers leukemia progression in a mouse model of chronic lymphocytic leukemia (CLL), supporting its role as a novel tumor restrainer. The aim of this study was to measure the amount of TIR8 mRNA and protein in CLL cells, and to analyze its regulation of expression. Circulating leukemic cells expressed lower levels of TIR8 compared to normal B-lymphocytes. Treatment of CLL cells with Azacytidine restored higher levels of TIR8 suggesting that DNA methylation may be involved in modulating TIR8 expression, with implications for novel therapeutic strategies.

Chlamydia pneumoniae induces interleukin-12 responses in peripheral blood mononuclear cells in asthma and the role of toll like receptor 2 versus 4: a pilot study

BACKGROUND

Chlamydia pneumoniae causes respiratory infection in adults and children, and has been associated with asthma exacerbations and induction of Immunoglobulin (Ig) E responses. We previously reported that C. pneumoniae enhances T helper (Th) 2 responses of peripheral blood mononuclear cells (PBMC) from asthmatic patients. It is likely that toll like receptor (TLR)-2 and TLR-4 mediate cytokine responses and host defense against C. pneumoniae. Thus, we sought to determine whether engagement of TLR-2 or TLR-4 may induce IL-12 production in our C. pneumoniae model.

METHODS

PBMC (1.5 × 10⁶) from asthmatic patients (N = 10) and non-asthmatic controls (N = 5) were infected or mock-infected for 1 h ± C. pneumoniae TW183 at a multiplicity of infection (MOI) = 1 and MOI = 0.1, and cultured for 48 h ± anti- TLR-2 and TLR-4 antibodies (Abs) (1 mg/mL). Interleukin (IL)-12 (48 h p.i.) and total IgE levels (day 10) were measured in supernatants (ELISA).

RESULTS

High IgE levels were detected in supernatants of C. pneumoniae- infected PBMC from asthmatics on day 10, compared with mock-infected PBMC (p < 0.03). In contrast, IgE was not detected (<0.3 ng/mL) in either C. pneumoniae infected or mock-infected PBMC from non-asthmatics. IL-12 production by C. pneumoniae-infected asthmatic and non-asthmatic PBMC were similar. When anti-TLR4, but not anti-TLR2, was included in culture, IL-12 production by C. pneumoniae- infected asthmatic PBMC decreased.

CONCLUSIONS

C. pneumoniae infection induces IgE production and modulates IL-12 responses in patients with asthma, which may be caused, in part, by differences in TLR-2 and TLR-4 stimulation.

Peroxiredoxin-3 Is Involved in Bactericidal Activity through the Regulation of Mitochondrial Reactive Oxygen Species

Peroxiredoxin-3 (Prdx3) is a mitochondrial protein of the thioredoxin family of antioxidant peroxidases and is the principal peroxidase responsible for metabolizing mitochondrial hydrogen peroxide. Recent reports have shown that mitochondrial reactive oxygen species (mROS) contribute to macrophage-mediated bactericidal activity in response to Toll-like receptors. Herein, we investigated the functional effect of Prdx3 in bactericidal activity. The mitochondrial localization of Prdx3 in HEK293T cells was confirmed by cell fractionation and confocal microscopy analyses. To investigate the functional role of Prdx3 in bactericidal activity, Prdx3-knockdown (Prdx3^KD) THP-1 cells were generated. The mROS levels in Prdx3^KD THP-1 cells were significantly higher than those in control THP-1 cells. Moreover, the mROS levels were markedly increased in response to lipopolysaccharide. Notably, the Salmonella enterica serovar Typhimurium infection assay revealed that the Prdx3^KD THP-1 cells were significantly resistant to S. Typhimurium infection, as compared with control THP-1 cells. Taken together, these results indicate that Prdx3 is functionally important in bactericidal activity through the regulation of mROS.

Altered pattern of tumor necrosis factor-alpha production in peripheral blood monocytes from Crohn's disease

AIM

To evaluate the inflammatory state in Crohn’s disease (CD) patients and correlate it with genetic background and microbial spreading.

METHODS

By means of flow cytometry, production of tumor necrosis factor-alpha (TNF-α) was measured in peripheral blood monocytes from patients suffering from CD, ulcerative colitis (UC) and in healthy subjects after stimulation of the NOD2 and TLR pathways. CD patients were genotyped for the three most common NOD2 variants (R702W, G908R and L1007Pfs*2) and basal production of TNF-α was correlated to NOD2 genotype. Also, production of TNF-α was correlated to plasmatic levels of LPS Binding Protein (LBP), soluble (s) CD14 and to the activity state of the disease.

RESULTS

The patients with CD were characterized by a significantly higher monocyte basal expression of TNF-α compared with healthy subjects and UC patients, and after stimulation with Pam₃CSK₄ (ligand of TLR2/1) and MDP-L18 (ligand of NOD2) this difference was maintained, while other microbial stimuli (LPS, ligand of TLR4 and PolyI:C, ligand of TLR3) induced massive activation in CD monocytes as well as in UC and in healthy control cells. There was no significant difference in the production of TNF-α between patients who carried CD-associated heterozygous or homozygous variants in NOD2 and patients with wild type NOD2 genotype. Although serum LBP levels have been shown to correlate positively with the state of activity of the disease, TNF-α production did not show a clear correlation with either LBP or sCD14 levels in plasma. Moreover, no clear correlation was seen between TNF-α production and activity indices in either CD or UC.

CONCLUSION

Peripheral monocytes from CD express higher basal and stimulated TNF-α than controls, regardless of NOD2 genotype and without a clear correlation with disease activity.

Impaired toll like receptor 9 response in pulmonary tuberculosis

BACKGROUND & AIM

Innate immune responses are important in susceptibility to pulmonary tuberculosis (TB). In order to test the hypothesis that Toll-like receptor (TLR) 2 function would be abnormal in patients with active pulmonary TB we compared the cytokine responses of peripheral blood mononuclear cells (PBMC) to innate immune ligands in a case-control study.

METHODS

PBMC from 19 untreated pulmonary TB patients, 17 healthy controls, and 11 treated pulmonary TB patients, were cultured for 24h with TLR 2 ligand (PAM-CSK) and other TLR ligands (muramyl dipeptide, flagellin, lipopolysaccharide (LPS), CpG oligodeoxynucleotide (CpG-ODN)). Interleukin-8 (IL-8) was estimated in the supernatant by ELISA. Messenger RNA expression for inflammatory cytokines was quantitated using real time PCR.

RESULTS

The important findings were (1) reduced PBMC secretion of IL-8 in response to all ligands in active TB; (2) normal to increased PBMC secretion of IL-8 in response to all ligands except CpG ODN (TLR 9 ligand) in TB patients who had recovered; (3) absence of difference in mRNA expression for a consortium of inflammatory pathway genes between healthy controls, active pulmonary tuberculosis and treated pulmonary tuberculosis patients.

CONCLUSION

There was a generalized post-translational suppression of the IL-8 response to innate immune ligands in active TB. There appears to be a defect of TLR 9 signaling in patients with tuberculosis, the nature of which needs to be further explored.

Quercetin attenuates the activation of hepatic stellate cells and liver fibrosis in mice through modulation of HMGB1-TLR2/4-NF-κB signaling pathways

This study aimed to investigate the effects of quercetin on liver fibrogenesis in mice and to elucidate the underlying molecular mechanisms. Mice were administered with carbon tetrachloride (CCl₄) for eight weeks to induce liver fibrosis and concomitantly orally treated with quercetin (50mgkg^-1day^-1). Here, we demonstrated that quercetin dramatically ameliorated liver injury, inflammation, and hepatic fibrogenesis induced by CCl₄. Quercetin also inhibited the activation of hepatic stellate cells (HSC) in vivo and in vitro, as evaluated by α-smooth muscle actin (α-SMA) expression, which is a specific marker of HSC activation. Moreover, reduced fibrosis was associated with decreased high-mobility group box 1 (HMGB1), toll like receptor (TLR) 2 and TLR4 genes, and protein expression. Quercetin also inhibited the cytoplasmic translocation of HMGB1 in hepatocytes of fibrotic livers. Further investigation demonstrated that quercetin treatment significantly attenuated CCl₄-induced nuclear translocation of the nuclear factor-κB (NF-κB) p65 and inhibited degradation of IκBα (an inhibitor of NF-κB) expression in the liver compared with vehicle-treated fibrotic mice. Considered together, our data indicate that quercetin has hepatoprotective and anti-fibrotic effects in animal models of liver fibrosis, the mechanism of which may be involved in modulating the HMGB1-TLR2/4-NF-κB signaling pathways.

[Role of Toll like receptors and inflammasome in aseptic loosening]

Aseptic loosening, ascribes to particle induced osteolysis, is the most common reason for total joint arthroplasty failure. Wear particles, liberated from the surface of prostheses, mediate the expression of inflammatory cytokines in macrophages and increase the osteoclastogenesis. However, it remains unclear how macrophages can recognize wear particles and be induced by wear particles. Recently, a number of studies have demonstrated that Toll like receptors and inflammasome may play a critical role in osteolysis. However, the mechanism of activation of Toll like receptors and the relationship between TLR pathway and downstream signaling pathways still remain unclear. It will be beneficial to understand the pathogenesis of aseptic loosening by exploring these mechanisms. This article highlights the role of Toll like receptors and inflammasome in aseptic loosening, which is helpful to the development of therapies that prevent wear particle induced aseptic loosening.

Effects of 5-aminolevulinic acid photodynamic therapy on TLRs in acne lesions and keratinocytes co-cultured with P. acnes

OBJECTIVE

To investigate the effect of 5-aminolevulinic acid photodynamic therapy (ALA-PDT) on the expression of Toll like receptors (TLRs) in human keratinocytes and its role in acne treatment.

METHODS

TLR2 and TLR4 expression in acne lesions before and after ALA-PDT were examined by immunohistochemical assay. Primary keratinocytes were obtained from acne lesions, co-cultured with P. acnes and then treated with ALA-PDT using red or blue LED. Cytokines production were examined by ELISA, TLR2 and TLR4 gene expression by real-time PCR, and TLR2 and TLR4 protein expression by Western-blot assay.

RESULTS

The overexpression of TLR2 and TLR4 in acne lesion were detected, which became negative or weaker after ALA-PDT. The infection of P. acnes in keratinocytes could significantly increase the levels of early inflammatory cytokines (e.g. IL-1α, TNF-α and IL-8) (P<0.05). Such responses could be inhibited by ALA-PDT. P. acnes infection could also significantly increase TLR2 and TLR4 expressions in keratinocytes (P<0.05), which could be down-regulated by ALA-PDT.

CONCLUSIONS

ALA-PDT could inhibit innate immune responses in keratinocytes treated with P. acnes via TLRs pathways.

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.

Toll-like receptors in the pathogenesis of pulmonary fibrosis

Pulmonary fibrosis (PF) constitutes the end stage of a broad range of heterogeneous interstitial lung diseases, characterized by the destruction of the pulmonary parenchyma, deposition of extracellular matrix and dramatic changes in the phenotype of both fibroblasts and alveolar epithelial cells. More than 200 causes of pulmonary fibrosis have been identified so far, yet the most common form is idiopathic pulmonary fibrosis (IPF). IPF is a lethal lung disorder of unknown etiology with a gradually increasing worldwide incidence and a median survival of 3-5 years from the time of diagnosis. Despite intense research efforts, the pathogenesis remains elusive and no effective treatment is available. Accumulating body of evidence suggests an abnormal wound healing response followed by extracellular matrix deposition, destruction of lung architecture, ultimately leading to respiratory failure. The contribution of immune system in lung fibrogenesis had been largely underscored due to the absence of response to immunosuppressive agents; however, the premise that lung fibrosis has an immunologic background has been recently revived. Toll-like receptors (TLRs) are pattern recognition receptors (PRRs), which link innate and adaptive immune response and regulate wound healing. TLRs promote tissue repair or fibrosis in many disease settings including lung fibrosis, albeit with profound differences depending on the cellular microenvironment. This review summarizes the current state of knowledge regarding the mechanistic implications between TLRs and lung fibrosis and highlights the therapeutic potential of targeting TLR signaling at the ligand or receptor level.

Elevated level of pro inflammatory cytokine and chemokine expression in chicken bone marrow and monocyte derived dendritic cells following LPS induced maturation

The study was designed to characterize and compare chicken bone marrow and peripheral blood monocyte derived dendritic cells (chBM-DC and chMoDC) and to evaluate inflammatory cytokine and chemokine alterations in response upon LPS stimulation. Typical morphology was observed in DCs from 48h of culture using recombinant chicken GM-CSF and IL-4. Maturation of DCs with LPS (1μg/ml) showed significant up regulation of mRNA of surface markers (CD40, CD80, CD83, CD86, MHC-II and DC-LAMP (CD208)), pro-inflammatory cytokines (IL-1β, IL-6, TNF-α (LITAF)), iNOS, chemokine CXCli2 and TLRs4 and 15. Basal level of TLR1 mRNA expression was higher followed by TLR15 in both DCs irrespective of their origin. Expression of iNOS and CXCLi2 mRNA in mature DCs of both origins were higher than other surface molecules and cytokines studied. Hence, its level of expression can also be used as an additional maturation marker for LPS induced chicken dendritic cell maturation along with CD83 and CD40. LPS matured DCs of both origins upregulated IL-12 and IFN-γ. Based on CD40 and CD83 mRNA expression, it was observed that LPS induced the maturation in both DCs, but chMoDCs responded better in expression of surface markers and inflammatory mediator genes.

Etiology and medical management of NEC

Necrotising enterocolitis (NEC) is a serious infection of the bowel that predominantly affects preterm infants and is a leading cause for mortality and morbidity in preterm infants. It involves a spectrum of pathology including widespread inflammation of the intestinal mucosa, invasion of the immature gut by enteric gas forming bacteria, dissection of the gut wall and portal veins by this gas, often culminating in ischemic necrosis of the intestine. This article provides an overview of the incidence, etio-pathological risk factors, preventive strategies and medical management of NEC.

In situ vaccination: Cancer immunotherapy both personalized and off-the-shelf

As cancer immunotherapy continues to benefit from novel approaches which cut immune 'brake pedals' (e.g. anti-PD1 and anti-CTLA4 antibodies) and push immune cell gas pedals (e.g. IL2, and IFNα) there will be increasing need to develop immune 'steering wheels' such as vaccines to guide the immune system specifically toward tumor associated antigens. Two primary hurdles in cancer vaccines have been: identification of universal antigens to be used in 'off-the-shelf' vaccines for common cancers, and 2) logistical hurdles of ex vivo production of individualized whole tumor cell vaccines. Here we summarize approaches using 'in situ vaccination' in which intratumoral administration of off-the-shelf immunomodulators have been developed to specifically induce (or amplify) T cell responses to each patient's individual tumor. Clinical studies have confirmed the induction of systemic immune and clinical responses to such approaches and preclinical models have suggested ways to further potentiate the translation of in situ vaccine trials for our patients.

TLR stimulation of human neutrophils lead to increased release of MCP-1, MIP-1α, IL-1β, IL-8 and TNF during tuberculosis

Neutrophils inform and shape immune responses. Toll-like receptors (TLRs) play an essential part in the perception of microbes and shape the complex host responses that occur during infection. The TLRs present on neutrophils play an indispensable role in neutrophil mediated pathogen recognition and elimination. This study was done to identify the role of significant TLRs in immune responses leading to differences in cytokine/chemokine release following stimulation. We evaluated the concentrations of various significant cytokines (IL-1β, TNF, MIP-1α, MCP-1 and IL-8) secreted by neutrophils from healthy donors and pulmonary tuberculosis patients following TLR ligand stimulation. TLR stimulation increased the release of such cytokines in both the groups. Thus it is noted that TLR stimulation of neutrophils definitely lead to increased cytokine response. Also, the release of all the studied cytokines are found to be greatly increased in patient neutrophils, affirming that neutrophils undergo secretory level modifications during tuberculosis infection.

MAP of F1 and V antigens from Yersinia pestis astride innate and adaptive immune response

Yersinia pestis, a causative agent of plague, has a plethora of armors to fight against major components of innate immunity and survive within host cells. Dendritic cells and macrophages are important antigen presenting cells for effective immune response. This report is focused on the changes in DC activation and TLR2 and TLR4 expression on macrophages induced by MAP of F1 and V antigens of Y. pestis. F1 and V MAPs bear potential synthetic T and B cell epitopes from F1 and V protein respectively. We evaluated these parameters in DC's isolated from spleen and lamina propria and macrophages isolated from peritoneal lavage of mice after intranasal immunization. F1 MAP and V MAP significantly increased the expression of CD80 and CD86 on CD11c(+) dendritic cells isolated from spleen and lamina propria as well as intracellular IL-12 levels. Similarly, in macrophages derived from peritoneal cavity, the above formulation enhanced TLR2 and TLR4 expression. Again after in vitro stimulation with F1 and V MAP these macrophages produced significantly high IL12 and TNFα. The study clearly indicates involvement of DC and macrophages for efficient antigen presentation to immune cells. From this study we conclude that F1MAP and VMAP ameliorate innate immune mechanism. These two synthetic constructs exert their effect via TLR2 and TLR4, leading to the production of proinflammatory cytokines by macrophages and are able to increase DC activation, that could be helpful in generation of adaptive immunity as well as is important strong immune response.