TLR2 and TLR4 expression during bacterial infections

Immunomodulatory effects of a probiotic combination treatment to improve the survival of Pacific oyster (Crassostrea gigas) larvae against infection by Vibrio coralliilyticus

Introduction

The culture of Pacific oysters (Crassostrea gigas) is of significant socio-economic importance in the U.S. Pacific Northwest and other temperate regions worldwide, with disease outbreaks acting as significant bottlenecks to the successful production of healthy seed larvae. Therefore, the current study aims to describe the mechanisms of a probiotic combination in improving the survival of C. gigas larvae. Specifically, we investigate changes in C. gigas larval gene expression in response to V. coralliilyticus infection with or without a pre-treatment of a novel probiotic combination.

Methods

Treatment groups consisted of replicates of Pacific oyster larvae exposed to a) a combination of four probiotic bacteria at a total concentration of 3.0 x 105 CFU/mL at 18 hours post-fertilization (hpf), b) pathogenic V. coralliilyticus RE22 at a concentration of 6.0 x 103 CFU/mL at 48 hpf, and c) the probiotic combination at 18 hpf and V. coralliilyticus RE22 at 48 hpf. RNA was extracted from washed larvae after 72 hpf, and transcriptome sequencing was used to identify significant differentially expressed genes (DEGs) within each treatment.

Results

Larvae challenged with V. coralliilyticus showed enhanced expression of genes responsible for inhibiting immune signaling (i.e., TNFAIP3, PSMD10) and inducing apoptosis (i.e., CDIP53). However, when pre-treated with the probiotic combination, these genes were no longer differentially expressed relative to untreated control larvae. Additionally, pre-treatment with the probiotic combination increased expression of immune signaling proteins and immune effectors (i.e., IL-17, MyD88). Apparent immunomodulation in response to probiotic treatment corresponds to an increase in the survival of C. gigas larvae infected with V. coralliilyticus by up to 82%.

Discussion

These results indicate that infection with V. coralliilyticus can suppress the larval immune response while also prompting cell death. Furthermore, the results suggest that the probiotic combination treatment negates the deleterious effects of V. coralliilyticus on larval gene expression while stimulating the expression of genes involved in infection defense mechanisms.

Efficacy of a recombinant M-like protein, SimA as a subunit vaccine candidate against Streptococcus parauberis infection in olive flounder, Paralichthys olivaceus

Streptococcus parauberis, a gram-positive cocci, causes bacterial disease in farmed fish. The recent increase in S. parauberis infection in aquatic farms in South Korea has justified the importance of vaccine development for the prevention of this disease. In this study, we evaluated the effect of subunit vaccines prepared from recombinant M-like protein (SimA) and fibrinogen-binding protein (FBP) candidates with an aluminum hydroxide adjuvant against S. parauberis infection in olive flounder Paralichthys olivaceus. For the in vivo experiment, fish (average length, 7.18 cm; average weight, 3.5 g) were injected intraperitoneally with: phosphate buffer saline (PBS, group 1), PBS/aluminum hydroxide (group 2), FBP/aluminum hydroxide (group 3), SimA/aluminum hydroxide (group 4), and SimA/FBP/aluminum hydroxide (group 5). After 3 weeks, the fish in each group were boosted using PBS (group 1 and 2), FBP (group 3), SimA (group 4), and SimA/FBP (group 5) without adjuvant. We found that the relative percent survival of fish after S. parauberis exposure in group 2, 3, 4, and 5 was 6.25%, 18.75%, 50%, and 12.5%, respectively, whereas the mortality in groups 1 was 80%, respectively. We performed Western blot, ELISA, and quantitative real time RT-PCR (qRT-PCR) after vaccination to investigate the further efficacy of the vaccine. Western blot and ELISA of vaccinated fish serum confirmed the production of specific antibodies against SimA and FBP. Furthermore, results of qRT-PCR showed that recombinant protein SimA induced a remarkably specific-antibody response compared with that in FBP or control and increased the expression of various immune response-related genes including interleukin-8 (IL-8), toll-like receptor 2 (TLR2), tumor necrosis factor-α (TNF-α), CD4-1, and MHC II. Thus, these results indicate that SimA is a potent vaccine candidate for protection against S. parauberis infection.

Different expression patterns of inflammatory cytokines induced by lipopolysaccharides from Escherichia coli or Porphyromonas gingivalis in human dental pulp stem cells

Background

Lipopolysaccharide (LPS) is one of the leading causes of pulpitis. The differences in establishing an in vitro pulpitis model by using different lipopolysaccharides (LPSs) are unknown. This study aimed to determine the discrepancy in the ability to induce the expression of inflammatory cytokines and the underlying mechanism between Escherichia coli (E. coli) and Porphyromonas gingivalis (P. gingivalis) LPSs in human dental pulp stem cells (hDPSCs).

Material and methods

Quantitative real-time polymerase chain reaction (QRT-PCR) was used to evaluate the mRNA levels of inflammatory cytokines including IL-6, IL-8, COX-2, IL-1β, and TNF-α expressed by hDPSCs at each time point. ELISA was used to assess the interleukin-6 (IL-6) protein level. The role of toll-like receptors (TLR)2 and TLR4 in the inflammatory response in hDPSCs initiated by LPSs was assessed by QRT-PCR and flow cytometry.

Results

The E. coli LPS significantly enhanced the mRNA expression of inflammatory cytokines and the production of the IL-6 protein (p < 0.05) in hDPSCs. The peaks of all observed inflammation mediators’ expression in hDPSCs were reached 3–12 h after stimulation by 1 μg/mL E. coli LPS. E. coli LPS enhanced the TLR4 expression (p < 0.05) but not TLR2 in hDPSCs, whereas P. gingivalis LPS did not affect TLR2 or TLR4 expression in hDPSCs. The TLR4 inhibitor pretreatment significantly inhibited the gene expression of inflammatory cytokines upregulated by E. coli LPS (p < 0.05).

Conclusion

Under the condition of this study, E. coli LPS but not P. gingivalis LPS is effective in promoting the expression of inflammatory cytokines by hDPSCs. E. coli LPS increases the TLR4 expression in hDPSCs. P. gingivalis LPS has no effect on TLR2 or TLR4 expression in hDPSCs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-022-02161-x.

Clostridioides difficile toxins enhanced the in vitro production of CXC chemokine ligand 2 and tumor necrosis factor-α via Toll-like receptors in macrophages

Introduction. Clostridioides difficile infection (CDI) causes toxin-mediated enteropathy, such as antibiotic-associated diarrhoea and pseudomembranous colitis. Rho-glucosylating toxin A (TcdA) and toxin B (TcdB) have been clearly implicated in pathogenesis, whereas the virulence of binary toxin (CDT) is still debated.Hypothesis statement. We hypothesized that CDT is involved in the host immune response and plays a pivotal role in establishing virulence by modulating pro-inflammatory cytokine production; this is achieved through the integral Toll-like receptor (TLR) signalling pathways.Aim. The aim of the present study was to determine whether and how CDT impacts macrophages compared to TcdA or TcdB by examining the induction of CXC chemokine ligand 2 (CXCL2) and tumour necrosis factor-α (TNF-α), both of which are crucial in mediating local and systematic inflammatory responses.Methodology. RAW264.7 cells or transfected human embryonic kidney (HEK) 293 T cells were incubated with TcdA, TcdB, or CDT. In some experiments, a neutralizing antibody against TLR2 or TLR4, or myeloid differentiation 88 inhibitory peptide were added. The amount of CXCL2 and TNF-α secreted was then measured.Results. In RAW264.7 macrophages, CXCL2 and TNF-α were produced via the Toll-like receptor 2 (TLR2) or Toll-like receptor 4 (TLR4) pathway in a TcdA, TcdB, or CDT dose-dependent manner. Interleukin-8 secretion was induced in TLR4/MD2/CD14-transfected, but not in TLR2-transfected, HEK 293 T cells following TcdB or CDT exposure.Conclusion. Our results showed that C. difficile toxins, including CDT, enhanced macrophage-mediated CXCL2 and TNF-α production via TLR2 and TLR4, indicating that CDT affects host immune responses.

MicroRNA-574-5p Attenuates Acute Respiratory Distress Syndrome by Targeting HMGB1

Acute respiratory distress syndrome (ARDS) is a critical condition with high mortality. HMGB1 (high-mobility group protein B1) is one of the key proinflammatory factors in the ARDS “inflammatory storm.” According to previous studies, some microRNAs (miRNAs) play important roles in this process. We aimed to determine the contributing miRNAs targeting the expression and release of HMGB1. miRNA expression in the peripheral blood of patients with ARDS was measured by miRNA microarray. miRNAs targeting HMGB1 were screened and explored for further study. In LPS-induced cell and mouse ARDS models, we explored the effect of this miRNA on the expression and secretion of HMGB1 by Western blot, real-time qPCR, and ELISA. The effects of this miRNA on the NF-κB signaling pathway, proinflammatory cytokines, and NLRP3 (nod-like receptor protein 3) inflammasome were detected by Western blot and real-time qPCR. In ARDS models, microRNA-574-5p (miR-574-5p) expression could be induced by the TLR4/NF-κB pathway upon LPS stimulation. It could suppress the inflammatory response by targeting HMGB1. Enforcing the expression of miR-574-5p or HMGB1 siRNA silencing inhibits the activation of NF-κB signaling pathway and the NLRP3 inflammasome. Moreover, overexpression of HMGB1 reversed the antiinflammatory effect of miR-574-5p. In ARDS mice, overexpression of miR-574-5p suppresses alveolar leukocytes infiltration, interstitial edema, protein effusion, and inflammation. This study demonstrated that miR-574-5p provided negative feedback to LPS-induced inflammation and relieved ARDS. It may provide new therapeutic strategies for ARDS.

Effect of human breast milk on innate immune response: Up-regulation of bacterial pattern recognition receptors and innate cytokines in THP-1 monocytic cells

Human breast milk (HBM) contains many bioactive components that protect infants from various microorganisms. Pattern recognition receptors on phagocytic cells recognize microbial pathogens and promote the innate immune system. This study aimed to evaluate the effect of HBM on the expression of pattern recognition receptors and innate cytokines in the monocytic cell line THP-1 and the phagocytic activity of RAW264.7 macrophages. Expression levels of specific mRNAs in THP-1 cells were quantitated using reverse transcription-polymerase chain reaction. Phagocytic activity was measured by fluorescence microscopy to detect the uptake of fluorescent dye-labeled carboxylate-modified polystyrene latex beads in RAW264.7 macrophages. HBM stimulated the phagocytic activity of RAW264.7 macrophages. HBM increased mRNA expression of pattern recognition receptors, including the cluster of differentiation 14 and toll-like receptor 2 and 4, and various innate cytokines, including tumor necrosis factor α, interleukin-1β, C-X-C motif chemokine 8, and C-C motif chemokine ligand 2, in THP-1 monocytic cells. Furthermore, milk oligosaccharides in HBM, such as lacto- N-fucopentaose I, enhanced the expression of pattern recognition receptors and various innate cytokines. HBM is able to modulate the innate immune response by upregulating the expression of pattern recognition receptors and various innate cytokines in monocytes/macrophages.

Estimation of Nitrite-Nitric Oxide Derivative-In Horses with Intestinal Colic by ESR Spectroscopy

Diseases of the gastrointestinal tract of horses are caused by many factors and have a complex pathogenesis. Developing effective methods of differential diagnostics is of high fundamental and applied importance. The pathogenesis of diseases of the digestive tract of horses accompanied by the development of inflammation and oxidative stress, can be associated with a lack of the nitrogen monoxide which controls many signaling pathways in the body. The level of the nitric oxide (NO) is involved in the regulation of the immune and nervous systems, the tone of all the blood vessels, and the courses of many pathological processes. The nitric oxide activates guanylate cyclase (sGC) and leads to vascular relaxation. The aim of this investigation was to study the metabolites of nitric oxide in horses suffered from intestinal diseases. The levels of nitric oxide in the blood serum of horses depending on their age and health state was studied. The concentration of nitrites in the blood serum of horses aged 6–25 years was 3.4 ± 4.2 μM, and in the young horses (1–5 years) the level of this indicator was 8.2 ± 5.4 μM. A sharp decrease in nitrite was observed in all the horses with intestinal diseases of 2 ± 0.9 μM, especially with tympanitic caecun of 0.6 ± 0.4 μM and with spasmodic colic of 1.8 ± 0.5 μM. The level of nitrosylhemoglobin HbNO in the blood of the diseased animals was higher than that in clinically healthy horses, regardless of age.

γ-Oryzanol-Rich Black Rice Bran Extract Enhances the Innate Immune Response

The innate immune response is an important host primary defense system against pathogens. γ-Oryzanol is one of the nutritionally important phytoceutical components in rice bran oil. The goal of this study was to investigate the effect of γ-oryzanol-rich extract from black rice bran (γORE) on the activation of the innate immune system. In this study, we show that γORE increased the expression of CD14 and Toll-like receptor 4 and enhanced the phagocytic activity of RAW264.7 macrophages. Furthermore, γORE and its active ingredient γ-oryzanol promoted the secretion of innate cytokines, interleukin-8, and CCL2, which facilitate phagocytosis by RAW264.7 cells. These findings suggest that γ-oryzanol in the γORE enhances innate immune responses.

Association of single-nucleotide polymorphisms in toll-like receptor 2 gene with asthma susceptibility: A meta-analysis

BACKGROUND

An increasing number of studies have been carried out on the relationship between polymorphisms in toll-like receptor 2 (TLR2) gene and asthma risk. However, the results were controversial. With the purpose of yielding a more reliable estimation of the association, we conducted the present meta-analysis.

METHODS

Multiple electronic databases up to August 22, 2016 were searched for literature retrieval. The association between the asthma susceptibility and the rs5743708 polymorphism, rs3804099 polymorphism, rs3804100 polymorphism, and rs4696480 polymorphism in TLR2 gene was appraised. The odds ratios (ORs) with 95% confidence intervals (CIs) under different genetic models were calculated.

RESULTS

A total of 13 studies were eligible in our meta-analysis according to the predefined inclusion and exclusion criteria. There was no significant association between asthma risk and rs5743708, rs3804099, and rs3804100 polymorphisms in TLR2 gene under any genetic model. With respect to the TLR2 rs4696480 polymorphism, significant association was detected between asthma susceptibility and TLR2 rs4696480 polymorphism under dominant model (OR = 2.455, 95% CI = 1.235-4.88, P = .01) and codominant 3 model (OR = 2.776, 95% CI = 1.199-6.427,  = 0.017).

CONCLUSIONS

Our meta-analysis reveals that the TLR2 rs4696480 polymorphism is significantly associated with asthma susceptibility, and the TLR2 rs4696480 polymorphism is a risk factor for asthma.

Leishmania donovani-Induced Increase in Macrophage Bcl-2 Favors Parasite Survival

Members of the Bcl-2 family are major regulators of apoptosis in mammalian cells, and hence infection-induced perturbations in their expression could result into elimination of the parasites or creation of a niche favoring survival. In this investigation, we uncover a novel role of host Bcl-2 in sustaining Leishmania donovani infection. A rapid twofold increase in Bcl-2 expression occurred in response to parasite challenge. Downregulation of post infection Bcl-2 increase using siRNA or functional inhibition using Bcl-2 small molecule inhibitors interfered with intracellular parasite survival confirming the necessity of elevated Bcl-2 during infection. An increased nitric oxide (NO) response and reduced parasitic burden was observed upon Bcl-2 inhibition, where restitution of the NO response accounted for parasite mortality. Mechanistic insights revealed a major role of elevated Th₂ cytokine IL-13 in parasite-induced Bcl-2 expression via the transcription factor STAT-3, where blocking at the level of IL-13 receptor or downstream kinase JAK-2 dampened Bcl-2 induction. Increase in Bcl-2 was orchestrated through Toll like receptor (TLR)-2-MEK-ERK signaling, and changes in TLR-2 levels affected parasite uptake. In a mouse model of visceral leishmaniasis (VL), Bcl-2 inhibitors partially restored the antimicrobial NO response by at least a twofold increase that resulted in significantly reduced parasite burden. Interestingly, monocytes derived from the peripheral blood of six out of nine human VL subjects demonstrated Bcl-2 expression at significantly higher levels, and sera from these patients showed only marginally quantifiable nitrites. Collectively, our study for the first time reveals a pro-parasitic role of host Bcl-2 and the capacity of host-derived IL-13 to modulate NO levels during infection via Bcl-2. Here, we propose Bcl-2 inhibition as a possible therapeutic intervention for VL.

Activation of Toll‐like receptor 9 inhibits lipopolysaccharide‐induced receptor activator of nuclear factor kappa‐ B ligand expression in rat B lymphocytes

B lymphocytes express multiple TLRs that regulate their cytokine production.We investigated the effect of TLR4 and TLR9 activation on receptor activator of NF‐kB ligand (RANKL) expression by rat spleen B cells. Splenocytes or purified spleen B cells from Rowett rats were cultured with TLR4 ligand Escherichia coli LPS and/or TLR9 ligand CpG‐oligodeoxynucleotide (CpG‐ODN) for 2 days. RANKL mRNA expression and the percentage of RANKL‐positive B cells were increased in rat splenocytes challenged by E. coli LPS alone. The increases were less pronounced when cells were treated with both CpG‐ODN and E. coli LPS. Microarray analysis showed that expressions of multiple cyclin‐dependent kinase (CDK) pathway‐related genes were up‐regulated only in cells treated with both E. coli LPS and CpG-ODN. This study suggests that CpG‐ODN inhibits LPS‐induced RANKL expression in rat B cells via regulation of the CDK pathway.

Different effects of P. gingivalis LPS and E. coli LPS on the expression of interleukin-6 in human gingival fibroblasts

OBJECTIVE

Gingival fibroblasts (GFs) produce pro-inflammatory cytokines in response to stimulation with lipopolysaccharide (LPS) of Porphyromonas gingivalis, which is thought to be mediated by activation of toll-like receptors (TLR)2 and TLR4. The present study investigated the expression of interleukin (IL)-6, TLR2, and TLR4 in GFs of seven different donors upon stimulation with P. gingivalis LPS. The effects of P. gingivalis LPS were compared with those of TLR4 agonist Escherichia coli LPS and TLR2 agonist Pam3CSK4.

MATERIALS AND METHODS

GFs were stimulated with P. gingivalis LPS, E. coli LPS or Pam3CSK4 and the expression of IL-6, TLR2 and TLR4 was measured by qPCR. The surface expression of TLR2 and TLR4 was measured by flow cytometry.

RESULTS

In GFs from three donors, P. gingivalis LPS and Pam3CSK4 induced a markedly lower increase in IL-6 expression than E. coli LPS. This was accompanied by significant down-regulation of the TLR2 and TLR4 expression. In GFs from another four donors, an increase in IL-6 expression upon stimulation with P. gingivalis LPS and Pam3CSK4 was similar or even higher than that induced by E. coli LPS. In GFs of these donors, all stimuli induced an up-regulation of both mRNA and protein expression of TLR2 and did not influence that of TLR4.

CONCLUSIONS

This study suggests that P. gingivalis LPS and E. coli LPS differently regulate cytokine production in human gingival fibroblasts. Regulation of the expression level of TLR2 and TLR4 by periodontal pathogens might be an important factor controlling the inflammatory response in GFs.

MicroRNA-302b augments host defense to bacteria by regulating inflammatory responses via feedback to TLR/IRAK4 circuits

MicroRNAs (miRNAs) have been implicated in a spectrum of physiological and pathological conditions, including immune responses. miR-302b has been implicated in stem cell differentiation but its role in immunity remains unknown. Here we show that miR-302b is induced by TLR2 and TLR4 through ERK-p38-NF-κB signaling upon Gram-negative bacterium Pseudomonas aeruginosa infection. Suppression of inflammatory responses to bacterial infection is mediated by targeting IRAK4, a protein required for the activation and nuclear translocation of NF-κB. Through negative feedback, enforced expression of miR-302b or IRAK4 siRNA silencing inhibits downstream NF-κB signaling and airway leukocyte infiltration, thereby alleviating lung injury and increasing survival in P. aeruginosa-infected mice. In contrast, miR-302b inhibitors exacerbate inflammatory responses and decrease survival in P. aeruginosa-infected mice and lung cells. These findings reveal that miR-302b is a novel inflammatory regulator of NF-κB activation in respiratory bacterial infections by providing negative feedback to TLRs-mediated immunity.

The immunoregulatory function of vitamin D: implications in chronic kidney disease

Cardiovascular and infectious diseases remain the most common causes of death among patients with chronic kidney disease (CKD) and end-stage renal disease (ESRD). Basic science and epidemiological studies indicate that vitamin D has importance not only for cardiovascular health, but also for the immune response. Vitamin D signaling pathways regulate both innate and adaptive immunity, maintaining the associated inflammatory response within physiological limits. Levels of both the inactive as well as active form of vitamin D (25-hydroxyvitamin D and 1,25-dihydroxyvitamin D, respectively) are decreased in patients with CKD and ESRD. It is reasonable to hypothesize, therefore, that the immune dysfunction associated with vitamin D deficiency in patients with CKD and ESRD in part explains the misdirected inflammatory response and increased susceptibility to infection seen in this population. Indeed, observational studies show that vitamin D deficiency in patients with ESRD is associated with increased mortality, and treatment with vitamin D is associated with a decreased risk of infection, as well as reduced all-cause mortality. However, whether different vitamin D preparations have differential effects on physiological function and clinical outcomes is still unclear. A proper understanding of the immune regulatory function of vitamin D is important for the development of future therapeutic strategies.

Scavenger receptor CD36 expression contributes to adipose tissue inflammation and cell death in diet-induced obesity

Objective

The enlarged adipose tissue in obesity is characterized by inflammation, including the recruitment and infiltration of macrophages and lymphocytes. The objective of this study was to investigate the role of the scavenger receptor CD36 in high fat diet-induced obesity and adipose tissue inflammation and cell death.

Experimental Approach

Obesity and adipose tissue inflammation was compared in CD36 deficient (CD36 KO) mice and wild type (WT) mice fed a high fat diet (60% kcal fat) for 16 weeks and the inflammatory response was studied in primary adipocytes and macrophages isolated from CD36 KO and WT mice.

Results

Compared to WT mice, CD36 KO mice fed a high fat diet exhibited reduced adiposity and adipose tissue inflammation, with decreased adipocyte cell death, pro-inflammatory cytokine expression and macrophage and T-cell accumulation. In primary cell culture, the absence of CD36 expression in macrophages decreased pro-inflammatory cytokine, pro-apoptotic and ER stress gene expression in response to lipopolysaccharide (LPS). Likewise, CD36 deficiency in primary adipocytes reduced pro-inflammatory cytokine and chemokine secretion in response to LPS. Primary macrophage and adipocyte co-culture experiments showed that these cell types act synergistically in their inflammatory response to LPS and that CD36 modulates such synergistic effects.

Conclusions

CD36 enhances adipose tissue inflammation and cell death in diet-induced obesity through its expression in both macrophages and adipocytes.

Vitamin D deficiency in obese rats exacerbates nonalcoholic fatty liver disease and increases hepatic resistin and Toll-like receptor activation

Childhood obesity is associated with type 2 diabetes mellitus and nonalcoholic fatty liver disease (NAFLD). Recent studies have found associations between vitamin D deficiency (VDD), insulin resistance (IR), and NAFLD among overweight children. To further explore mechanisms mediating these effects, we fed young (age 25 days) Sprague-Dawley rats with a low-fat diet (LFD) alone or with vitamin D depletion (LFD+VDD). A second group of rats was exposed to a Westernized diet (WD: high-fat/high-fructose corn syrup) that is more typically consumed by overweight children, and was either replete (WD) or deficient in vitamin D (WD+VDD). Liver histology was assessed using the nonalcoholic steatohepatitis (NASH) Clinical Research Network (CRN) scoring system and expression of genes involved in inflammatory pathways were measured in liver and visceral adipose tissue after 10 weeks. In VDD groups, 25-OH-vitamin D levels were reduced to 29% (95% confidence interval [CI]: 23%-36%) compared to controls. WD+VDD animals exhibited significantly greater hepatic steatosis compared to LFD groups. Lobular inflammation as well as NAFLD Activity Score (NAS) were higher in WD+VDD versus the WD group (NAS: WD+VDD 3.2 ± 0.47 versus WD 1.50 ± 0.48, P < 0.05). Hepatic messenger RNA (mRNA) levels of Toll-like receptors (TLR)2, TLR4, and TLR9, as well as resistin, interleukins (IL)-1β, IL-4, and IL-6 and oxidative stress marker heme oxygenase (HO)-1, were higher in WD+VDD versus WD animals (P < 0.05). Logistic regression analyses showed significant associations between NAS score and liver mRNA levels of TLRs 2, 4, and 9, endotoxin receptor CD14, as well as peroxisome proliferator activated receptor (PPAR)γ, and HO-1.

CONCLUSION

VDD exacerbates NAFLD through TLR-activation, possibly by way of endotoxin exposure in a WD rat model. In addition it causes IR, higher hepatic resistin gene expression, and up-regulation of hepatic inflammatory and oxidative stress genes.

The proteoglycan biglycan enhances antigen-specific T cell activation potentially via MyD88 and TRIF pathways and triggers autoimmune perimyocarditis

Biglycan is a proteoglycan ubiquitously present in extracellular matrix of a variety of organs, including heart, and it was reported to be overexpressed in myocardial infarction. Myocardial infarction may be complicated by perimyocarditis through unknown mechanisms. Our aim was to investigate the capacity of TLR2/TLR4 ligand biglycan to enhance the presentation of specific Ags released upon cardiomyocyte necrosis. In vitro, OVA-pulsed bone marrow-derived dendritic cells from wild-type (WT; C57BL/6) and TLR2-, TLR4-, MyD88-, or TRIF-deficient mice were cotreated with LPS, biglycan, or vehicle and incubated with OVA-recognizing MHC I- or MHC II-restricted T cells. Biglycan enhanced OVA-specific cross-priming by >80% to MHC I-restricted T cells in both TLR2- and TLR4-pathway-dependent manners. Accordingly, biglycan-induced cross-priming by both MyD88- and TRIF-deficient dendritic cells (DCs) was strongly diminished. OVA-specific activation of MHC II-restricted T cells was predominantly TLR4 dependent. Our first in vivo correlate was a model of experimental autoimmune perimyocarditis triggered by injection of cardiac Ag-pulsed DCs (BALB/c). Biglycan-treated DCs triggered perimyocarditis to a comparable extent and intensity as LPS-treated DCs (mean scores 1.3 ± 0.3 and 1.5 ± 0.4, respectively). Substitution with TLR4-deficient DCs abolished this effect. In a second in vivo approach, WT and biglycan-deficient mice were followed 2 wk after induction of myocardial infarction. WT mice demonstrated significantly greater myocardial T lymphocyte infiltration in comparison with biglycan-deficient animals. We concluded that the TLR2/4 ligand biglycan, a component of the myocardial matrix, may enhance Ag-specific T cell priming, potentially via MyD88 and TRIF, and stimulate autoimmune perimyocarditis.

Expression of toll-like receptors in genital tract tissues from normal and HIV-infected men

PROBLEM

cells of the innate immune system use Toll-like receptors (TLRs) to recognize and respond to invading pathogens. This study was carried out to characterize TLR expression in the human male genital tract, an initial infection site for several sexually transmitted pathogens.

METHOD OF STUDY

immunohistochemistry was used to detect expression of TLRs 1-9 in genital tract tissues from HIV(-) and HIV(+) men.

RESULTS

in HIV(-) men, TLR1(+) leukocytes were detected throughout the genital tract. Leukocytes in the penile urethra also expressed TLRs2, 3, 5, 7 and 9. Epithelial cells in most tissues did not express TLRs; exceptions were the prostate, where TLRs3 and 8 were observed on the apical surface of luminal epithelial cells, and the penile urethra, where epithelial cells expressed TLR9. In genital tissues from HIV(+) men with AIDS, few TLR(+) cells were detected.

CONCLUSION

cells in the male genital tract can express a variety of TLRs. The penile urethra contained the highest number of TLR(+) cells, indicating that this tissue plays a major role in the innate immune defense of the male genital tract. Overall, TLR expression was reduced in genital tissues from HIV(+) men.

Expression of Toll-like Receptors 2 and 4 in Subplacental Trophoblasts From Guinea Pigs (Cavia porcellus) Following Infection With Campylobacter jejuni

Toll-like receptors 2 and 4 (TLR2 and TLR4) are well-characterized cell surface receptors that recognize specific pathogen-associated molecular patterns and play an important role in pathogen recognition and activation of the innate immune system. Variable expression of TLR2 and TLR4 has been described in trophoblasts from normal and diseased placentas; yet, there are limited data regarding trophoblast TLR expression in response to specific placental pathogens, and TLR expression in the guinea pig placenta has not been described. The guinea pig is an effective model for Campylobacter-induced abortion of small ruminants, and the authors have shown by immunohistochemistry that C jejuni localizes within syncytiotrophoblasts of the guinea pig subplacenta. The present study was designed to determine if the expression of either TLR2 or TLR4 would be affected in subplacental trophoblasts following infection with C jejuni. Immunohistochemistry for TLR2 and TLR4 was performed on placenta from guinea pigs that aborted following inoculation with C jejuni and from sham-inoculated controls. Quantitative assessment of TLR expression was performed, and mean immunoreactivity for TLR2 was significantly higher in subplacental trophoblasts from animals that aborted compared with uninfected controls ( P = .0283), whereas TLR4 expression was not statistically different ( P = .5909). These results suggest that abortion in guinea pigs following infection with C jejuni is associated with increased TLR2 expression in subplacental trophoblasts and may reveal a possible role for TLR2 in the pathogenesis of Campylobacter-induced abortion.

Toward general prophylactic cancer vaccination

It is well established that chronic infections can lead to cancer. Almost unknown is that, in contrast, acute brief viral and bacterial infections may have beneficial effects in cases of established neoplastic disease, while exposure to pathogenic products by infection, vaccination, and inhalation can cause prophylactic effects. In the following I will align evidence from case studies of spontaneous regression and from epidemiological studies with recent immunology to conclude that pathogenic substances belonging to the group of "pathogen-associated molecular patterns" can trigger the innate immune system to establish anti-neoplastic immune responses. A better understanding of the protective role of the innate immune system might leverage considerable prophylactic potential.

Innate immune recognition of, and response to, Clostridium sordellii

Clostridium sordellii, an anaerobic pathogen, has recently been associated with rapidly fatal infections following medically induced abortions and injecting drug use. Patients with C. sordellii infection display few signs of inflammation such as fever, or redness and pain at the site of infection. We hypothesized that this could be due to reduced recognition of the organism by Toll-like receptors (TLRs) of the innate immune system. An ELAM-NF-kappaB luciferase reporter system in TLR-transfected HEK cells was used to measure TLR-dependent recognition of washed, heat-killed C. sordellii and other pathogenic clostridial species. Results demonstrated that all clostridia were well recognized by TLR2 alone and that responses were greatest when TLR2 was co-expressed with TLR6. Further, isolated human monocytes produced the pro-inflammatory cytokine TNFalpha and the immunoregulator IL-10 in response to C. sordellii. In addition, C. sordellii-stimulated monocytes produced 30% less TNFalpha following treatment with an anti-TLR2 blocking antibody. These data demonstrate that innate immune recognition of, and response to, cell-associated components of C. sordellii and other clostridial pathogens are mediated by TLR2 in combination with TLR6. We conclude that the characteristic absence of inflammatory signs and symptoms in C. sordellii infection is not related to inadequate immune detection of the organism, but rather is attributable to a species-specific immune system dysfunction that remains to be elucidated.

Surface RANKL of Toll-like receptor 4-stimulated human neutrophils activates osteoclastic bone resorption

Inflammatory bone loss in septic and inflammatory conditions is due to increased activity of osteoclasts that requires receptor activator of NF-kappa B-ligand (RANKL). Neutrophils are the predominant infiltrating cells in these conditions. Although disease severity is linked to neutrophils, their role in evolution of bony lesions is not clear. We show that lipopolysaccharide (LPS), a toll-like receptor 4 ligand, up-regulated the expression of membrane RANKL in human blood neutrophils and murine air pouch-derived neutrophils. LPS-activated human and murine neutrophils, cocultured with human monocyte-derived osteoclasts and RAW 264.7 cells, respectively, stimulated bone resorption. Transfection of PLB-985 neutrophil-like cells with RANKL antisense RNA reduced osteoclastogenesis. Synovial fluid neutrophils of patients with exacerbation of rheumatoid arthritis strongly expressed RANKL and activated osteoclastogenesis in coculture systems. Osteoprotegerin, the RANKL decoy receptor, suppressed osteoclast activation by neutrophils from these different sources. Moreover, direct cell-cell contact between neutrophils and osteoclasts was visualized by confocal laser microscopy. Activation of neutrophil membrane-bound RANKL was linked to tyrosine phosphorylation of Src-homology domain-containing cytosolic phosphatase 1 with concomitant down-regulation of cytokine production. The demonstration of these novel functions of neutrophils highlights their potential role in osteoimmunology and in therapeutics of inflammatory bone disease.

Effect of Jianpi Huoxue decoction-containing serum on tumor necrosis factor-alpha secretion and gene expression of endotoxin receptors in RAW264.7 cells induced by lipopolysaccharide

OBJECTIVE

To evaluate the effect of Jianpi Huoxue decoction (JHD)-containing serum on tumor necrosis factor-alpha (TNF-alpha) secretion and endotoxin receptor gene expression in RAW264.7 cells induced by lipopolysaccharide (LPS).

METHODS

The cytotoxicity of blank-control serum and JHD-containing serum at different concentrations were evaluated through the lactate dehydrogenase (LDH) assay in RAW264.7 cells. RAW264.7 cells were divided into six groups: 5% blank-control serum group (C1, n=3), 5% blank-control serum plus LPS group (L1, n=4), 5% JHD-containing serum plus LPS group (J1, n=4), 10% blank-control serum group (C2, n=3), 10% blank-control serum plus LPS group (L2, n=4), and 10% JHD-containing serum plus LPS group (J2, n=4). After cultured with the corresponding serum for 1 h, cells in L1, L2, J1 and J2 were treated with LPS (0.1 microg/mL) for 12 h without rinse. The supernate, cells, protein and RNA were collected for assay. TNF-alpha in the culture supernate was assayed by the enzyme linked immunosorbent assay (ELISA). Protein expression of TNF-alpha in RAW cells was detected by Western-blot. TNF-alpha, Toll-like receptor 2 (TLR2), TLR4 and CD14 mRNA expression in RAW cells were detected by real-time RT-PCR.

RESULTS

The LDH assay supported that cultured for 24 h or less with the JHD-containing serum at the concentration of 10% or lower, RAW264.7 cells showed no cytotoxicity. After stimulation with LPS for 2 h, TNF-alpha in the culture supernate of the 5% blank-control serum plus LPS group (L1, P=0.03), 10% blank-control serum plus LPS group (L2, P=0.002) and in the cell layer (P=0.01) of these groups increased remarkably. After stimulation with LPS for 1 h, the mRNA expression of TNF-alpha (P=0.004), TLR (P=0.03), CD14 (P=0.004) was up-regulated obviously. In the 10% JHD-containing serum plus LPS group (J2), the protein expression of TNF-alpha in both supernate (P=0.04) and cell layer (P=0.04), gene expression of TNF-alpha (P=0.03), TLR4 (P=0.001), CD14 (P=0.001) were all inhibited. On the other hand, the TLR2 mRNA expression was not up-regulated after LPS stimulation in the 10% blank-control serum plus LPS group (L2).

CONCLUSION

JHD-containing serum inhibited the LPS-induced cytokines expression in RAW264.7 which was probably associated with its inhibitory effect on the mRNA expression of LPS receptors TLR and CD14.

'Renal hypersensitivity' to inulin and IgA nephropathy

Hypersensitivity to inulin (polyfructan) is a rare event; two cases of food allergy and some patients presenting with allergy and hypersensitivity after inulin infusion have been reported. An 11-year-old boy suffering from severe immunoglobulin (Ig)A nephropathy (IgAN) experienced both anaphylactic reaction and concomitant relapse of his nephropathy following inulin infusion, used for measuring glomerular filtration rate (GFR) 2 years after the appearance of his initial symptoms. Pruritus, wheezing and cough were observed during a first renal function test; results of prick and intradermal tests were negative for inulin. The patient presented with pallor, asthenia and oliguria when a second inulin infusion was performed under dexchlorpheniramine, leading to the immediate cessation of the infusion. He was readmitted 2 days later because of fatigue and nausea related to acute renal failure. A drug-induced acute interstitial nephritis was first suspected. However, due to the presence of macroscopic haematuria and proteinuria, a renal biopsy was performed and showed acute proliferative relapse of IgAN. The underlying mechanism of inulin hypersensitivity is not well known. We can hypothesize that inulin had activated the innate immune system. Inulin may, thus, have been the initiating event of the renal relapse, acting like an infection, in a patient with IgA-mediated immunological dysregulation.

Effect of JIANPI HUOXUE decoction on inflammatory cytokine secretion pathway in rat liver with lipopolysaccharide challenge

AIM: To evaluate the effect of Chinese traditional medicinal prescription, JIANPI HUOXUE decoction (JHD) on cytokine secretion pathway in rat liver induced by lipopolysaccharide (LPS).

METHODS: Twenty-four male SD rats were divided into normal group (n = 4), model group (n = 10) and JHD group (n = 10) randomly. Rats in model group and JHD group were administrated with normal saline or JHD via gastrogavage respectively twice a day for 3 d. One hour after the last administration, rats were injected with LPS via tail vein, 50 &mgr;g/kg. Simultaneously, rats in normal group were injected with equivalent normal saline. After LPS stimulation for 1.5 h, serum and liver tissue were collected. Pathological change of liver tissues was observed through hematoxylin-eosin (H.E.) staining. Tumor necrosis factor alpha (TNF-α) in serum were assayed by enzyme linked immunosorbent assay (ELISA). The protein expression of TNF-α, phosphorylated inhibit-κB (p-IκB) and CD68 in liver were assayed by Western blot. The distribution of CD68 protein in liver was observed through immunohistochemical staining. The mRNA expression of TNF-α, interleukin-6 (IL-6), CD14, toll-like receptor 2 (TLR2) and TLR4 in liver were assayed by real-time RT-PCR.

RESULTS: Predominant microvesicular change, hepatocyte tumefaction and cytoplasm dilution were observed in liver tissues after LPS administration as well as obvious CD68 positive staining in hepatic sinusoidal. After LPS stimulation, serum TNF-α (31.35 ± 6.06 vs 12 225.40 ± 9007.03, P < 0.05), protein expression of CD68 (1.13 ± 0.49 vs 3.36 ± 1.69, P < 0.05), p-IκB (0.01 ± 0.01 vs 2.07 ± 0.83, P < 0.01) and TNF-α (0.27 ± 0.13 vs 1.29 ± 0.37, P < 0.01) in liver and mRNA expression of TNF-α (1.96 ± 2.23 vs 21.45 ± 6.00, P < 0.01), IL-6 (4.80 ± 6.42 vs 193.50 ± 36.36, P < 0.01) and TLR2 (1.44 ± 0.62 vs 4.16 ± 0.08, P < 0.01) in liver were also increased significantly. These pathological changes were all improved in JHD group. On the other hand, TLR4 mRNA (1.22 ± 0.30 vs 0.50 ± 0.15, P < 0.05) was down-regulated and CD14 mRNA increased but not significantly after LPS stimulation.

CONCLUSION: JHD can inhibit cytokine secretion pathway induced by LPS in rat liver, which is probably associated with its regulation on CD68, p-IκB and endotoxin receptor TLR2.

Bacterial peptidoglycan breaks down intestinal tolerance via mast cell activation: the role of TLR2 and NOD2

Intestinal microbes are believed to be involved in the pathogenesis of inflammatory bowel disease. Microbes and their products are generally well tolerated by intestinal epithelial cells in the intestinal tract of healthy individuals. It is of significance to understand what breaks down the established tolerance leading to intestinal barrier dysfunction and intestinal inflammation. T84 monolayer transported peptidoglycan (PGN) was determined by enzyme-linked immune assay. Mast cell line HMC-1 cell activation in response to PGN stimulation was observed with electron microscopy and measurement of histamine release. T84 monolayer barrier function was determined by recording the transepithelial electric resistance (TER) and measuring the permeability in response to PGN-induced HMC-1 cell activation. Expression of Toll-like receptor (TLR) 2 and nucleotide-binding oligomerization domain (NOD) 2 were determined by immunocytochemistry, real-time reverse transcription (RT)-PCR and Western blot. Exposure to PGN alone did not alter TER and permeability of T84 monolayers. T84 monolayers transported PGN from the apical chamber to the basal chamber of transwell system. TLR2 expressed on the surface of HMC-1 cells. HMC-1 cells absorbed PGN. HMC-1 cells released histamine in response to the PGN stimulation, which was blocked by pretreatment with antibodies or small interfering RNA against TLR2 or NOD2. In a co-culture system, T84 monolayer transported PGN activated HMC-1 cells and increased the horseradish peroxidase flux. TLR2 mediated the PGN-absorption in HMC-1 cells. Blockade of TLR2 or NOD2 abolished PGN-induced HMC-1 cell activation and T84 monolayer barrier dysfunction. T84 monolayer transported PGN activates HMC-1 cells to release chemical mediators to induce T84 monolayer dysfunction that are mediated by TLR2 and NOD2.