Toll-like receptors as potential therapeutic targets for multiple diseases

Participation of TLRs in cancer immunopathogenesis and drug resistance via interacting with immunological and/or non-immunological signaling pathways as well as lncRNAs

Toll-like receptors (TLRs) have a convoluted role in cancer even though they are crucial to the immune system. By bridging the innate immune system and cancer, TLRs have a very complex impact on the formation of tumors and the effectiveness of anti-cancer treatments. TLR signaling links the innate and adaptive immune systems and initiates direct pathogen eradication. In cancer immunopathogenesis and treatment resistance, long non-coding RNAs (lncRNAs) modify TLR signaling linkages with immunological and non-immunological pathways. We identified lncRNAs that positively and negatively control TLR signaling, impacting immunological response and drug sensitivity. These results highlight the complex interactions between long non-coding RNAs and TLRs that influence the start of cancer and its response to treatment. Targeting specific lncRNAs is a practical way to control TLR signaling and perhaps enhance anti-tumor immunity while overcoming medication resistance. We provide a framework for developing novel immunotherapeutic regimens and customized medicine approaches for cancer treatment. The exact mechanisms by which lncRNAs regulate TLR signaling pathways should be defined by further research, and these findings should be validated in clinical situations. This finding makes future research of lncRNA-based drugs in combination with existing cancer treatments feasible.

Molecule engineering strategy of toll-like receptor 7/8 agonists designed for potentiating immune stimuli activation

Toll-like receptor 7/8 (TLR-7/8) agonists serve as a promising class of pattern recognition receptors that effectively evoke the innate immune response, making them promising immunomodulatory agents for tumor immunotherapy. However, the uncontrollable administration of TLR-7/8 agonists frequently leads to the occurrence of severe immune-related adverse events (irAEs). Thus, it is imperative to strategically design tumor-microenvironment-associated biomarkers or exogenous stimuli responsive TLR-7/8 agonists in order to accurately evaluate and activate innate immune responses. No comprehensive elucidation has been documented thus far regarding TLR-7/8 immune agonists that are specifically engineered to enhance immune activation. In this feature article, we provide an overview of the advancements in TLR-7/8 agonists, aiming to enhance the comprehension of their mechanisms and promote the clinical progression through nanomedicine strategies. The current challenges and future directions of cancer immunotherapy are also discussed, with the hope that this work will inspire researchers to explore innovative applications for triggering immune responses through TLR-7/8 agonists.

Mulberry leaf polysaccharide improves cyclophosphamide-induced growth inhibition and intestinal damage in chicks by modulating intestinal flora, enhancing immune regulation and antioxidant capacity

Polysaccharides are generally considered to have immune enhancing functions, and mulberry leaf polysaccharide is the main active substance in mulberry leaves, while there are few studies on whether mulberry leaf polysaccharide (MLP) has an effect on immunosuppression and intestinal damage caused by cyclophosphamide (CTX), we investigated whether MLP has an ameliorative effect on intestinal damage caused by CTX. A total of 210 1-day-old Mahuang cocks were selected for this experiment. Were equally divided into six groups and used to evaluate the immune effect of MLP. Our results showed that MLP significantly enhanced the growth performance of chicks and significantly elevated the secretion of cytokines (IL-1β, IL-10, IL-6, TNF-α, and IFN-γ), immunoglobulins and antioxidant enzymes in the serum of immunosuppressed chicks. It attenuated jejunal damage and elevated the expression of jejunal tight junction proteins Claudin1, Zo-1 and MUC2, which protected intestinal health. MLP activated TLR4-MyD88-NF-κB pathway and enhanced the expression of TLR4, MyD88 and NF-κB, which served to protect the intestine. 16S rDNA gene high-throughput sequencing showed that MLP increased species richness, restored CTX-induced gut microbiome imbalance, and enhanced the abundance of probiotic bacteria in the gut. MLP improves cyclophosphamide-induced growth inhibition and intestinal damage in chicks by modulating intestinal flora and enhancing immune regulation and antioxidant capacity. In conclusion, this study provides a scientific basis for MLP as an immune enhancer to regulate chick intestinal flora and protect chick intestinal mucosal damage.

An Update on the Role and Potential Molecules in Relation to Ruminococcus gnavus in Inflammatory Bowel Disease, Obesity and Diabetes Mellitus

Ruminococcus gnavus (R. gnavus) is a gram-positive anaerobe commonly resides in the human gut microbiota. The advent of metagenomics has linked R. gnavus with various diseases, including inflammatory bowel disease (IBD), obesity, and diabetes mellitus (DM), which has become a growing area of investigation. The initial focus of research primarily centered on assessing the abundance of R. gnavus and its potential association with disease presentation, taking into account variations in sample size, sequencing and analysis methods. However, recent investigations have shifted towards elucidating the underlying mechanistic pathways through which R. gnavus may contribute to disease manifestation. In this comprehensive review, we aim to provide an updated synthesis of the current literature on R. gnavus in the context of IBD, obesity, and DM. We critically analyze relevant studies and summarize the potential molecular mediators implicated in the association between R. gnavus and these diseases. Across numerous studies, various molecules such as methylation-controlled J (MCJ), glucopolysaccharides, ursodeoxycholic acid (UDCA), interleukin(IL)-10, IL-17, and capric acid have been proposed as potential contributors to the link between R. gnavus and IBD. Similarly, in the realm of obesity, molecules such as hydrogen peroxide, butyrate, and UDCA have been suggested as potential mediators, while glycine ursodeoxycholic acid (GUDCA) has been implicated in the connection between R. gnavus and DM. Furthermore, it is imperative to emphasize the necessity for additional studies to evaluate the potential efficacy of targeting pathways associated with R. gnavus as a viable strategy for managing these diseases. These findings have significantly expanded our understanding of the functional role of R. gnavus in the context of IBD, obesity, and DM. This review aims to offer updated insights into the role and potential mechanisms of R. gnavus, as well as potential strategies for the treatment of these diseases.

Amygdalin Alleviates DSS-Induced Colitis by Restricting Cell Death and Inflammatory Response, Maintaining the Intestinal Barrier, and Modulating Intestinal Flora

Inflammatory bowel disease (IBD) refers to a cluster of intractable gastrointestinal disorders with an undetermined etiology and a lack of effective therapeutic agents. Amygdalin (Amy) is a glycoside extracted from the seeds of apricot and other Rosaceae plants and it exhibits a wide range of pharmacological properties. Here, the effects and mechanisms of Amy on colitis were examined via 16S rRNA sequencing, ELISA, transmission electron microscopy, Western blot, and immunofluorescence. The results showed that Amy administration remarkably attenuated the signs of colitis (reduced body weight, increased disease activity index, and shortened colon length) and histopathological damage in dextran sodium sulfate (DSS)-challenged mice. Further studies revealed that Amy administration significantly diminished DSS-triggered gut barrier dysfunction by lowering pro-inflammatory mediator levels, inhibiting oxidative stress, and reducing intestinal epithelial apoptosis and ferroptosis. Notably, Amy administration remarkably lowered DSS-triggered TLR4 expression and the phosphorylation of proteins related to the NF-κB and MAPK pathways. Furthermore, Amy administration modulated the balance of intestinal flora, including a selective rise in the abundance of S24-7 and a decline in the abundance of Allobaculum, Oscillospira, Bacteroides, Sutterella, and Shigella. In conclusion, Amy can alleviate colitis, which provides data to support the utility of Amy in combating IBD.

Structural Optimization and Biological Evaluation of Isoxazolo[5,4-d]pyrimidines as Selective Toll-Like Receptor 7 Agonists

Toll-like receptors (TLRs) are components of innate immunity that play a crucial role in several diseases, including chronic inflammatory and infectious diseases, autoimmune diseases, and cancer. In particular, TLR7 has been identified as a key player in the innate immune response against viral infections and small-molecule TLR7 agonists have shown potential for vaccine therapy, for treatment of asthma and allergies, and as anticancer drugs. Inspired by our previous discovery of selective TLR7 agonists, our goal was to develop and introduce a new chemotype of TLR7 agonists by replacing the quinazoline ring with a new heterocycle isoxazolo[5,4-d]pyrimidine. Here, we report design, optimized synthesis, and structure-activity relationship studies of a novel class of TLR7 agonists based on the 6-(trifluoromethyl)isoxazolo[5,4-d]pyrimidine-4-amine scaffold that demonstrate high selectivity and low micromolar potencies. The best-in-class agonist 21a, with an EC50 value of 7.8 μM, also proved to be noncytotoxic and induced secretion of cytokines, including IL-1β, IL-12p70, IL-8, and TNF-α, indicating its potential to modulate the immune response.

Black chokeberry (Aronia melanocarpa L.) polyphenols attenuate obesity-induced colonic inflammation by regulating gut microbiota and the TLR4/NF-κB signaling pathway in high fat diet-fed rats

This study investigated the potential benefits of black chokeberry polyphenol (BCP) supplementation on lipopolysaccharide (LPS)-stimulated inflammatory response in RAW264.7 cells and obesity-induced colonic inflammation in a high fat diet (HFD)-fed rat model. Our findings demonstrated that BCP treatment effectively reduced the production of nitric oxide (NO) and pro-inflammatory cytokines (TNF-α, IL-1β, IL-6, and MCP-1) in LPS-induced RAW264.7 cells and concurrently mitigated oxidative stress by modulating the levels of malondialdehyde (MDA), catalase (CAT), and glutathione peroxidase (GSH-Px) in a dose-dependent manner. Furthermore, BCP supplementation significantly ameliorated HFD-induced obesity, improved glucose tolerance, and reduced systemic inflammation in HFD-fed rats. Notably, BCP treatment suppressed the mRNA expression of pro-inflammatory cytokines and alleviated intestinal barrier dysfunction by regulating the mRNA and protein expression of key tight junction proteins (ZO-1, occludin, and claudin-1), thereby inhibiting colonic inflammation caused by the TLR4/NF-κB signaling pathway. Additionally, BCP treatment altered the composition and function of the gut microbiota, leading to an increase in the total content of short-chain fatty acids (SCFAs), particularly acetic acid, propionic acid, isobutyric acid, and butyric acid. Collectively, our results highlighted the potential of BCP supplementation as a promising prebiotic strategy for treating obesity-induced colonic inflammation.

Synthesis and Evaluation of a Self-Adjuvanting Pseudomonal Vaccine Based on Major Outer Membrane Porin OprF Epitopes Formulated with Low-Toxicity QS-21-Containing Liposomes

Pseudomonas aeruginosa (PA) is a Gram-negative pathogen that the World Health Organization has ranked as a priority 1 (critical) threat. One potential prophylactic approach to preventing or reducing the incidence of PA would be development of a long sought-after vaccine. Both antibody and CD4+ T-cell responses have been noted as playing key roles in protection against infection. In these studies, we have designed a prototype vaccine consisting of several known linear B-cell epitopes derived from an outer membrane porin F (OprF). The resulting thiol-containing protein was conjugated to a version of the lipopeptide-based Toll-like receptor agonist Pam3CysSK4Mal (10) containing a maleimide moiety and formulated into dipalmitoylphosphatidylcholine (DPPC)/cholesterol (Chol) liposomes. Mice immunized with the resulting vaccine generated antibodies that bound PA14 (serotype O10) in vitro and induced opsonization in the presence of rabbit complement and murine macrophage RAW264.7 cells. The liposome was optimized to contain 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), 1,2-dimyristoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (DMPG), Chol, Pam3CysSK4-OprF (12) and the Quillaja saponaria-derived saponin adjuvant QS-21. The resulting vaccine formulation produced significantly higher antibody titers, increased the IgG2a antibody isotype, and increased the number of IgG-producing B-cells as well as splenic primed T-cells. In summary, the liposomal vaccine platform was found highly useful for the generation of a robust and balanced TH1/TH2 response.

Obesity Is Associated with Immunometabolic Changes in Adipose Tissue That May Drive Treatment Resistance in Breast Cancer: Immune-Metabolic Reprogramming and Novel Therapeutic Strategies

White adipose tissue (WAT) represents an endocrinologically and immunologically active tissue whose primary role is energy storage and homeostasis. Breast WAT is involved in the secretion of hormones and proinflammatory molecules that are associated with breast cancer development and progression. The role of adiposity and systemic inflammation in immune responses and resistance to anti-cancer treatment in breast cancer (BC) patients is still not clear. Metformin has demonstrated antitumorigenic properties both in pre-clinical and clinical studies. Nevertheless, its immunomodulating properties in BC are largely unknown. This review aims to evaluate the emerging evidence on the crosstalk between adiposity and the immune-tumour microenvironment in BC, its progression and treatment resistance, and the immunometabolic role of metformin in BC. Adiposity, and by extension subclinical inflammation, are associated with metabolic dysfunction and changes in the immune-tumour microenvironment in BC. In oestrogen receptor positive (ER+) breast tumours, it is proposed that these changes are mediated via a paracrine interaction between macrophages and preadipocytes, leading to elevated aromatase expression and secretion of pro-inflammatory cytokines and adipokines in the breast tissue in patients who are obese or overweight. In HER2+ breast tumours, WAT inflammation has been shown to be associated with resistance to trastuzumab mediated via MAPK or PI3K pathways. Furthermore, adipose tissue in patients with obesity is associated with upregulation of immune checkpoints on T-cells that is partially mediated via immunomodulatory effects of leptin and has been paradoxically associated with improved responses to immunotherapy in several cancers. Metformin may play a role in the metabolic reprogramming of tumour-infiltrating immune cells that are dysregulated by systemic inflammation. In conclusion, evidence suggests that body composition and metabolic status are associated with patient outcomes. To optimise patient stratification and personalisation of treatment, prospective studies are required to evaluate the role of body composition and metabolic parameters in metabolic immune reprogramming with and without immunotherapy in patients with BC.

Histochemical assessment on osteoclasts in long bones of toll-like receptor 2 (TLR2) deficient mice

OBJECTIVE

Toll-like receptor 2 (TLR2), recognizes a wide variety of pathogen-associated molecular patterns such as lipopolysaccharides, peptidoglycans, and lipopeptides, and is generally believed to be present in monocytes, macrophages, dendritic cells, and vascular endothelial cells. However, no histological examination of osteoclasts, which differentiate from precursors common to macrophages/monocytes, has been performed in a non-infected state of TLR2 deficiency. The objective of this study was to examine the histological properties and function of osteoclasts in the long bones of 8-week-old male TLR2 deficient (TLR2^-/-) mice to gain insight into TLR2 function in biological circumstances without microbial infection.

METHODS

Eight-week-old male wild-type and TLR2^-/- mice were fixed with paraformaldehyde solution, and their tibiae and femora were used for micro-CT analysis, immunohistochemistry, transmission electron microscopy, and real-time PCR analysis.

RESULTS

TLR2^-/- tibiae and femora exhibited increased bone volume of metaphyseal trabeculae and elevated numbers of TRAP-positive osteoclasts. However, the number of multinucleated TRAP-positive osteoclasts was reduced, whereas mononuclear TRAP-positive cells increased, despite the high expression levels of Dc-Stamp and Oc-Stamp. Although TRAP-positive multinucleated and mononuclear osteoclasts showed the immunoreactivity and elevated expression of RANK and siglec-15, they revealed weak cathepsin K-positivity and less incorporation of the mineralized bone matrix, and often missing ruffled borders. It seemed likely that, despite the increased numbers, TLR2^-/- osteoclasts reduced cell fusion and bone resorption activity.

CONCLUSION

It seems likely that even without bacterial infection, TLR2 might participate in cell fusion and subsequent bone resorption of osteoclasts.

The role of hypothalamic endoplasmic reticulum stress in schizophrenia and antipsychotic-induced weight gain: A narrative review

Schizophrenia (SCZ) is a serious mental illness that affects 1% of people worldwide. SCZ is associated with a higher risk of developing metabolic disorders such as obesity. Antipsychotics are the main treatment for SCZ, but their side effects include significant weight gain/obesity. Despite extensive research, the underlying mechanisms by which SCZ and antipsychotic treatment induce weight gain/obesity remain unclear. Hypothalamic endoplasmic reticulum (ER) stress is one of the most important pathways that modulates inflammation, neuronal function, and energy balance. This review aimed to investigate the role of hypothalamic ER stress in SCZ and antipsychotic-induced weight gain/obesity. Preliminary evidence indicates that SCZ is associated with reduced dopamine D2 receptor (DRD2) signaling, which significantly regulates the ER stress pathway, suggesting the importance of ER stress in SCZ and its related metabolic disorders. Antipsychotics such as olanzapine activate ER stress in hypothalamic neurons. These effects may induce decreased proopiomelanocortin (POMC) processing, increased neuropeptide Y (NPY) and agouti-related protein (AgRP) expression, autophagy, and leptin and insulin resistance, resulting in hyperphagia, decreased energy expenditure, and central inflammation, thereby causing weight gain. By activating ER stress, antipsychotics such as olanzapine activate hypothalamic astrocytes and Toll-like receptor 4 signaling, thereby causing inflammation and weight gain/obesity. Moreover, evidence suggests that antipsychotic-induced ER stress may be related to their antagonistic effects on neurotransmitter receptors such as DRD2 and the histamine H1 receptor. Taken together, ER stress inhibitors could be a potential effective intervention against SCZ and antipsychotic-induced weight gain and inflammation.

Identification and immunological evaluation of novel TLR2 agonists through structural optimization of Diprovocim

As an important family member of Toll-like receptors (TLRs), TLR2 can recognize various pathogen-associated molecular patterns (PAMPs) such as bacteria and viral components. Accumulating evidence demonstrates that TLR2 agonists play a critical role in cancer immunotherapy and infectious diseases. Diprovocim is the most potent small molecule TLR2 agonist known, showing remarkably immune adjuvant activity in mice. However, the further clinical research and development of Diprovocim was hampered because of its structural complexity as well as high molecular weight. Here, we designed and synthesized 21 structurally simplified derivatives of Diprovocim, performed their TLR2 agonistic activities by HEK-Blue hTLR2 SEAP assay, and evaluated the toxicity in two human normal cell lines. Compounds B3-B4 and B9-B12 with excellent TLR2 agonistic activity were found through the structure-activity relationship study. Among them, diastereomer B10 and B12 substituted (S)-2-phenylcyclopropylamide side chain of Diprovocim with simple (R)- and (S)-n-butyl groups exhibited comparable TLR2 agonistic activities with EC₅₀ values of 35 nM and 39 nM, respectively. ELISA and western blot experiments on THP-1 cells showed that B10 and B12 displayed remarkable immunostimulatory activity in the release of various inflammatory cytokines through activating MyD88-dependent NF-κB and MAPK signaling pathways. Importantly, B10 and B12 have less structural complexity and better safety compared to Diprovocim, and the chiral center of right pyrrolidine ring has negligible influence on TLR2 activition. Our study provides simplified Diprovocim derivatives with high agonistic activity, providing a clue to further optimize Diprovocim.

Peitu Shengjin Recipe Attenuates Airway Inflammation via the TLR4/NF-kB Signaling Pathway on Chronic Obstructive Pulmonary Disease

Background

Chronic obstructive pulmonary disease (COPD) is a common respiratory disease, but there is no specific medicine for COPD. In this study, we aimed to evaluate the effects of Peitu Shengjin Recipe (PSR) and Biostime Probiotic Powder on COPD rats.

Methods

UPLC-Q/TOF-MS was used to detect the chemical constituents in PSR. The COPD rat model was established by cigarette smoke combined with tracheal injection of lipopolysaccharide. We assessed lung function by calculating FEV_0.3/FVC%, dynamic lung compliance (Cdyn), and resistance of inspiration (RI). Histological analysis was performed by HE staining. The levels of TNF-α, IFN-γ, IL-1β, IL-4, and IL-10 were detected by the ELISA. The mRNA and protein expressions of the TLR4/NF-kB signaling pathway were detected by the qRT-PCR and western blotting, respectively.

Results

There were 53 ESI⁺ and 50 ESI⁻ components in PSR. After high-dose PSR treatment, FEV_0.3/FVC% and Cdyn increased significantly, while RI decreased. Compared with the COPD model, the RI of the Biostime Probiotic Powder group was significantly lower. HE staining showed that the inflammatory cell infiltration was reduced to varying degrees, the bronchial tube wall was not thickened, and the alveoli were relatively intact after treatment with PSR and Biostime Probiotic Powder. Compared with the model group, the levels of TNF-α, IFN-γ, IL-1β, IL-4, and IL-10 in the PSR group and the Biostime Probiotic Powder group were reversed. The mRNA and protein expressions of TLR4 and NF-kB were significantly decreased after PSR and Biostime Probiotic Powder treatment.

Conclusion

Our findings suggest that PSR and Biostime Probiotic Powder have protective effects on COPD rats, which may be achieved by modulating the TLR4/NF-kB signaling pathway.

Host-pathogen protein-nucleic acid interactions: A comprehensive review

Recognition of pathogen-derived nucleic acids by host cells is an effective host strategy to detect pathogenic invasion and trigger immune responses. In the context of pathogen-specific pharmacology, there is a growing interest in mapping the interactions between pathogen-derived nucleic acids and host proteins. Insight into the principles of the structural and immunological mechanisms underlying such interactions and their roles in host defense is necessary to guide therapeutic intervention. Here, we discuss the newest advances in studies of molecular interactions involving pathogen nucleic acids and host factors, including their drug design, molecular structure and specific patterns. We observed that two groups of nucleic acid recognizing molecules, Toll-like receptors (TLRs) and the cytoplasmic retinoic acid-inducible gene (RIG)-I-like receptors (RLRs) form the backbone of host responses to pathogen nucleic acids, with additional support provided by absent in melanoma 2 (AIM2) and DNA-dependent activator of Interferons (IFNs)-regulatory factors (DAI) like cytosolic activity. We review the structural, immunological, and other biological aspects of these representative groups of molecules, especially in terms of their target specificity and affinity and challenges in leveraging host-pathogen protein-nucleic acid interactions (HP-PNI) in drug discovery.

Prognostic significance of crown-like structures to trastuzumab response in patients with primary invasive HER2 + breast carcinoma

Obesity can initiate, promote, and maintain systemic inflammation via metabolic reprogramming of macrophages that encircle adipocytes, termed crown-like structures (CLS). In breast cancer the presence of CLS has been correlated to high body mass index (BMI), larger mammary adipocyte size and postmenopausal status. However, the prognostic significance of CLS in HER2 + breast cancer is still unknown. We investigated the prognostic significance of CLS in a cohort of 69 trastuzumab-naïve and 117 adjuvant trastuzumab-treated patients with primary HER2 + breast cancer. Immunohistochemistry of tumour blocks was performed for CLS and correlated to clinical outcomes. CLS were more commonly found at the adipose-tumour border (B-CLS) (64.8% of patients). The presence of multiple B-CLS was associated with reduced time to metastatic disease (TMD) in trastuzumab treated patients with BMI ≥ 25 kg/m2 but not those with BMI < 25 kg/m2. Phenotypic analysis showed the presence of CD32B + B-CLS was strongly correlated to BMI ≥ 25 kg/m2 and reduced TMD in trastuzumab treated patients. Multivariable analysis suggested that CD32B + B-CLS positive tumours are associated with shorter TMD in trastuzumab-treated patients (HR 4.2 [95%CI, (1.01-17.4). This study indicates adipose-tumour border crown-like structures that are CD32B + potentially represent a biomarker for improved personalisation of treatment in HER2-overexpressed breast cancer patients.

Does the gut microbiome mediate antipsychotic-induced metabolic side effects in schizophrenia?

INTRODUCTION

Second-generation antipsychotics (SGAs) are the most effective treatment for people with schizophrenia. Despite their effectiveness in treating psychotic symptoms, they have been linked to metabolic, cardiovascular and gastrointestinal side-effects. The gut microbiome has been implicated in potentiating symptoms of schizophrenia, response to treatment and medication-induced side effects and thus presents a novel target mediating second-generation antipsychotic-induced side effects in patients.

AREAS COVERED

This narrative review presents evidence from clinical and pre-clinical studies exploring the relationship between the gut microbiome, schizophrenia, second-generation antipsychotics and antipsychotic-induced side-effects. It also covers evidence for psychobiotic treatment as a potential supplementary therapy for people with schizophrenia.

EXPERT OPINION

The gut microbiome has the potential to mediate antipsychotic-induced side-effects in people with schizophrenia. Microbiome-focused treatments should be considered in combination with standard therapy in order to ameliorate debilitating drug-induced side effects, increase quality of life and potentially improve psychotic symptoms. Future studies should aim to collect not only microbiome data, but also metabolomic measures, dietary information and behavioral data.

Partial Replacement of Dietary Fat with Krill Oil or Coconut Oil Alleviates Dyslipidemia by Partly Modulating Lipid Metabolism in Lipopolysaccharide-Injected Rats on a High-Fat Diet

This study investigated the effects of partial replacement of dietary fat with krill oil (KO) or coconut oil (CO) on dyslipidemia and lipid metabolism in rats fed with a high-fat diet (HFD). Sprague Dawley rats were divided into three groups as follows: HFD, HFD + KO, and HFD + CO. The rats were fed each diet for 10 weeks and then intraperitoneally injected with phosphate-buffered saline (PBS) or lipopolysaccharide (LPS) (1 mg/kg). The KO- and CO-fed rats exhibited lower levels of serum lipids and aspartate aminotransferases than those of the HFD-fed rats. Rats fed with HFD + KO displayed significantly lower hepatic histological scores and hepatic triglyceride (TG) content than rats fed with HFD. The KO supplementation also downregulated the adipogenic gene expression in the liver. When treated with LPS, the HFD + KO and HFD + CO groups reduced the adipocyte size in the epididymal white adipose tissues (EAT) relative to the HFD group. These results suggest that KO and CO could improve lipid metabolism dysfunction.

Herpes simplex virus interference with immunity: Focus on dendritic cells

Herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) are highly prevalent in the human population. These viruses cause lifelong infections by establishing latency in neurons and undergo sporadic reactivations that promote recurrent disease and new infections. The success of HSVs in persisting in infected individuals is likely due to their multiple molecular determinants involved in escaping the host antiviral and immune responses. Importantly, HSVs infect and negatively modulate the function of dendritic cells (DCs), key immune cells that are involved in establishing effective and balanced immunity against viruses. Here, we review and discuss several molecular and cellular processes modulated by HSVs in DCs, such as autophagy, apoptosis, and the unfolded protein response. Given the central role of DCs in establishing optimal antiviral immunity, particular emphasis should be given to the outcome of the interactions occurring between HSVs and DCs.

Mechanisms Underlying the Protective Effect of the Peroxiredoxin-6 Are Mediated via the Protection of Astrocytes during Ischemia/Reoxygenation

Ischemia-like conditions reflect almost the entire spectrum of events that occur during cerebral ischemia, including the induction of oxidative stress, Ca²⁺ overload, glutamate excitotoxicity, and activation of necrosis and apoptosis in brain cells. Mechanisms for the protective effects of the antioxidant enzyme peroxiredoxin-6 (Prx-6) on hippocampal cells during oxygen-glucose deprivation/reoxygenation (OGD/R) were investigated. Using the methods of fluorescence microscopy, inhibitory analysis, vitality tests and PCR, it was shown that 24-h incubation of mixed hippocampal cell cultures with Prx-6 does not affect the generation of a reversible phase of a OGD-induced rise in Ca²⁺ ions in cytosol ([Ca²⁺]_i), but inhibits a global increase in [Ca²⁺]_i in astrocytes completely and in neurons by 70%. In addition, after 40 min of OGD, cell necrosis is suppressed, especially in the astrocyte population. This effect is associated with the complex action of Prx-6 on neuroglial networks. As an antioxidant, Prx-6 has a more pronounced and astrocyte-directed effect, compared to the exogenous antioxidant vitamin E (Vit E). Prx-6 inhibits ROS production in mitochondria by increasing the antioxidant capacity of cells and altering the expression of genes encoding redox status proteins. Due to the close bond between [Ca²⁺]_i and intracellular ROS, this effect of Prx-6 is one of its protective mechanisms. Moreover, Prx-6 effectively suppresses not only necrosis, but also apoptosis during OGD and reoxygenation. Incubation with Prx-6 leads to activation of the basic expression of genes encoding protective kinases—PI3K, CaMKII, PKC, anti-apoptotic proteins—Stat3 and Bcl-2, while inhibiting the expression of signaling kinases and factors involved in apoptosis activation—Ikk, Src, NF-κb, Caspase-3, p53, Fas, etc. This effect on the basic expression of the genome leads to the cell preconditions, which is expressed in the inhibition of caspase-3 during OGD/reoxygenation. A significant effect of Prx-6 is directed on suppression of the level of pro-inflammatory cytokine IL-1β and factor TNFα, as well as genes encoding NMDA- and kainate receptor subunits, which was established for the first time for this antioxidant enzyme. The protective effect of Prx-6 is due to its antioxidant properties, since mutant Prx-6 (mutPrx-6, Prx6-C47S) leads to polar opposite effects, contributing to oxidative stress, activation of apoptosis and cell death through receptor action on TLR4.

Structural Evolution and Translational Potential for Agonists and Antagonists of Endosomal Toll-like Receptors

Toll-like receptors (TLRs) are members of a large family of evolutionarily conserved pattern recognition receptors (PRRs), which serve as key components of the innate immune system by playing a pivotal role in sensing "nonself" ligands. Endosomal TLRs (TLR3, TLR7, TLR8, and TLR9) can recognize pathogen-derived nucleic acid and initiate an innate immune response because they react against both self- and non-self-origin nucleic acid molecules. Accordingly, both receptor agonists and antagonists are potentially useful in disparate clinical contexts and thus are globally sought after. Recent research has revealed that agonists and antagonists share an overlapping binding region. This Perspective highlights rational medicinal chemistry approaches to elucidate the structural attributes of small molecules capable of agonism or antagonism or of elegantly switching between the two. The structural evolution of different chemotypes can provide the framework for the future development of endosomal TLR agonists and antagonists.

Ginsenoside Rk3 Ameliorates Obesity-Induced Colitis by Regulating of Intestinal Flora and the TLR4/NF-κB Signaling Pathway in C57BL/6 Mice

Obesity-induced colonic inflammation-stimulated colitis is one of the main causes of colorectal cancer. Dietary phytochemicals are considered to be an effective strategy for relieving obesity-induced inflammatory diseases such as diabetes and colitis. Ginsenoside Rk3 (Rk3) is the main bioactive component of ginseng. Our previous study has demonstrated that Rk3 can effectively alleviate obesity-induced type 2 diabetes, but whether it plays a beneficial role in obesity-induced colitis remains poorly understood. Here, we found that Rk3 intervention repaired the intestinal barrier dysfunction by increasing the expression of the tight junction proteins (zonula occludens-1, claudin, and occludin), and reduced colonic inflammatory cytokine levels, oxidative stress, and macrophage infiltration in high-fat diet-induced mice. Importantly, Rk3 effectively ameliorated the metabolic dysbiosis of intestinal flora with significantly decreased Firmicute/Bacteroidete ratios and suppressed the inflammatory cascade by inhibiting the TLR4/NF-κB signaling pathway. Taken together, our findings indicate that Rk3 can be used as a potential natural anti-inflammatory agent to reduce chronic obesity-induced colitis.

The role of the microbiome in diabetes mellitus

The microbiome is greatly significant for immune system development and homeostasis. Dysbiosis in gut microbial composition and function is linked to immune responses and the development of metabolic diseases, including diabetes mellitus (DM). However, skin microbiome changes in diabetic patients and their role in DM are poorly elucidated. In this review, we summarize recent findings about the association between the gut and skin microbiota and DM, highlighting their roles in the proinflammatory status of DM. Moreover, although there is evidence that the connection between the gut and skin causes the same activated innate immune response, additional studies are needed to explore the mechanism. These findings might inform future DM prevention, diagnosis and treatment.

Cardiolipin Synthase 1 Ameliorates NASH Through Activating Transcription Factor 3 Transcriptional Inactivation

BACKGROUND AND AIMS

NASH is an increasingly prevalent disease that is the major cause of liver dysfunction. Previous research has indicated that adipose cardiolipin synthase 1 (CRLS1) levels are associated with insulin sensitivity; however, the precise roles of CRLS1 and underlying mechanisms involving CRLS1 in the pathological process of NASH have not been elucidated.

APPROACH AND RESULTS

Here, we discovered that CRLS1 was significantly down-regulated in genetically obese and diet-induced mice models. In vitro studies demonstrated that overexpression of CRLS1 markedly attenuated hepatic steatosis and inflammation in hepatocytes, whereas short hairpin RNA-mediated CRLS1 knockdown aggravated these abnormalities. Moreover, high-fat diet-induced insulin resistance and hepatic steatosis were significantly exacerbated in hepatocyte-specific Crls1-knockout (Crls1-HKO) mice. It is worth noting that Crls1 depletion significantly aggravated high-fat and high-cholesterol diet-induced inflammatory response and fibrosis during NASH development. RNA-sequencing analysis systematically demonstrated a prominently aggravated lipid metabolism disorder in which inflammation and fibrosis resulted from Crls1 deficiency. Mechanically, activating transcription factor 3 (ATF3) was identified as the key differentially expressed gene in Crls1-HKO mice through transcriptomic analysis, and our investigation further showed that CRLS1 suppresses ATF3 expression and inhibits its activity in palmitic acid-stimulated hepatocytes, whereas ATF3 partially reverses lipid accumulation and inflammation inhibited by CRLS1 overexpression under metabolic stress.

CONCLUSIONS

In conclusion, CRLS1 ameliorates insulin resistance, hepatic steatosis, inflammation, and fibrosis during the pathological process of NASH by inhibiting the expression and activity of ATF3.

miR-383 ameliorates high glucose-induced β-cells apoptosis and hyperglycemia in high-fat induced diabetic mice

Islet beta-cell dysfunction is an important condition leading to the development of diabetes. Numerous studies have found that miRNA regulates islet β-cell function. In our previous research, the aberrant expression of miR-383 was revealed in type 2 diabetes mellitus (T2DM) serum. Herein, we aimed to assess the function and underlying mechanism of miR-383 in β-cells through in vitro and in vivo experiments. Using high glucose media, the β-cell injury was induced and transfected miR-383 overexpression vector to detect cell function in MIN6. Moreover, miR-383 overexpression lentivirus was administrated into high-fat induced diabetes mice to assess the in vivo effect. Results showed that overexpressing miR-383 reversed the cell apoptosis and oxidative stress, induced by high glucose which targets Toll-like receptors (TLR4) and Apolipoprotein C3 (ApoC3) genes. Furthermore, mechanistic studies demonstrated that miR-383 targeted the TLR4 and ApoC3 3' UTR consequently inhibiting TLR4 and ApoC3 expression in MIN6 cells. Besides, overexpression of miR-383 ameliorated hyperglycemia and pancreatic apoptosis in high-fat induced diabetic mice. Conclusively, miR-383 potentially alleviate pancreatic β-cell injury induced by high glucose and ameliorates high-fat induced diabetes by suppressing TLR4 and ApoC3 expression.

The Role of Peritoneal Fibrosis in Encapsulating Peritoneal Sclerosis

Encapsulating peritoneal sclerosis (EPS) is a serious complication of long-term continuous peritoneal dialysis therapy. The progression of EPS has been classified into four stages by Kawanishi and colleagues: pre-EPS, and the inflammatory, encapsulating, and ileus stages. The key issue is how to diagnose EPS early enough to allow for curative treatment. In this article, we review the mechanisms of peritoneal fibrosis, especially from the perspective of collagen synthesis, and the potential role of that fibrosis in the pathogenesis of EPS.

A peptide derived from the core β-sheet region of TIRAP decoys TLR4 and reduces inflammatory and autoimmune symptoms in murine models

BACKGROUND

TLRs are some of the actively pursued drug-targets in immune disorders. Owing to a recent surge in the cognizance of TLR structural biology and signalling pathways, numerous therapeutic modulators, ranging from low-molecular-weight organic compounds to polypeptides and nucleic acid agents have been developed.

METHODS

A penetratin-conjugated small peptide (TIP3), derived from the core β-sheet of TIRAP, was evaluated in vitro by monitoring the TLR-mediated cytokine induction and quantifying the protein expression using western blot. The therapeutic potential of TIP3 was further evaluated in TLR-dependent in vivo disease models.

FINDINGS

TIP3 blocks the TLR4-mediated cytokine production through both the MyD88- and TRIF-dependent pathways. A similar inhibitory-effect was exhibited for TLR3 but not on other TLRs. A profound therapeutic effect was observed in vivo, where TIP3 successfully alleviated the inflammatory response in mice model of collagen-induced arthritis and ameliorated the disease symptoms in psoriasis and SLE models.

INTERPRETATION

Our data suggest that TIP3 may be a potential lead candidate for the development of effective therapeutics against TLR-mediated autoimmune disorders.

FUNDING

This work was supported by the National Research Foundation of Korea (NRF-2019M3A9A8065098, 2019M3D1A1078940 and 2019R1A6A1A11051471). The funders did not have any role in the design of the present study, data collection, data analysis, interpretation, or the writing of the manuscript.

Arachidonic acid inhibits inflammatory responses by binding to myeloid differentiation factor-2 (MD2) and preventing MD2/toll-like receptor 4 signaling activation

Arachidonic acid (AA) plays a fundamental role in the function of all cells. Metabolites of AA contribute to inflammation as well as for resolving inflammation. Although AA-derived metabolites exhibit well-substantiated bioactivity, it is not known whether AA regulates inflammatory responses independent of its metabolites. With the recent discovery that saturated fatty acids activate toll-like receptor-4 (TLR4), we tested the hypothesis that AA directly regulates inflammatory responses through modulating the activity of TLR4. In cultured cardiomyocytes and macrophages, we found that AA prevents saturated fatty acid-induced TLR4 complex formation with accessory proteins and the induction of proinflammatory cytokines. We discovered that AA directly binds to TLR4 co-receptor, myeloid differentiation factor 2 (MD2) and prevents saturated fatty acids from activating TLR4 pro-inflammatory signaling pathway. Similarly, AA reduced lipopolysaccharide (LPS)-induced inflammation in macrophages and septic death in mice through binding to MD2. In high-fat diet mouse model of obesity and LPS-induced model of acute lung injury, both mediating inflammatory responses through TLR4, treatment with AA prevented MD2/TLR4 dimerization, induction of inflammatory factors, and tissue injuries. In summary, we have discovered that AA interacts with MD2 and disrupts TLR4 activation by LPS and saturated fatty acids. These findings provide experimental evidence for a direct mechanism of AA-induced regulation of inflammation.

CLEC2 and CLEC5A: Pathogenic Host Factors in Acute Viral Infections

The protective roles of endosomal toll-like receptors (TLRs) and cytosolic nucleic acid sensors are well elucidated, but the pathogenic host factors during viral infections remain unclear. Spleen tyrosine kinase (Syk)-coupled C-type lectins (CLECs) CLEC2 and CLEC5A are highly expressed on platelets and myeloid cells, respectively. CLEC2 has been shown to recognize snake venom aggretin and the endogenous ligand podoplanin and acts as a critical regulator in the development and immunothrombosis. Although CLEC2 has been reported to interact with type I immunodeficiency virus (HIV-1), its role in viral infections is still unclear. CLEC5A binds to fucose and mannose moieties of dengue virus membrane glycans, as well as to N-acetylglucosamine (GlcNAc)/N-acetylmuramic acid (MurNAc) disaccharides that form the backbone of L. monocytogenes peptidoglycans. Recently, we demonstrated that both CLEC2 and CLEC5A are critical in microbe-induced “neutrophil extracellular trap” (NET) formation and proinflammatory cytokine production. Moreover, activation of CLEC2 by dengue virus (DV) and H5N1 influenza virus (IAV) induces the release of extracellular vesicles (EVs), which further enhance NETosis and proinflammatory cytokine production via CLEC5A and Toll-like receptor 2 (TLR2). These findings not only illustrate the immunomodulatory effects of EVs during platelet-leukocyte interactions, but also demonstrate the critical roles of CLEC2 and CLEC5A in acute viral infections.

Pharmacological modulation of nucleic acid sensors - therapeutic potential and persisting obstacles

Nucleic acid sensors, primarily TLR and RLR family members, as well as cGAS-STING signalling, play a critical role in the preservation of cellular and organismal homeostasis. Accordingly, deregulated nucleic acid sensing contributes to the origin of a diverse range of disorders, including infectious diseases, as well as cardiovascular, autoimmune and neoplastic conditions. Accumulating evidence indicates that normalizing aberrant nucleic acid sensing can mediate robust therapeutic effects. However, targeting nucleic acid sensors with pharmacological agents, such as STING agonists, presents multiple obstacles, including drug-, target-, disease- and host-related issues. Here, we discuss preclinical and clinical data supporting the potential of this therapeutic paradigm and highlight key limitations and possible strategies to overcome them.

Signals trigger state-specific transcriptional programs to support diversity and homeostasis in immune cells

Macrophages play key roles in the immune systems of humans and other mammals. Here, we performed single-cell analyses of the mRNAs and proteins of human macrophages to compare their responses to the signaling molecules lipopolysaccharide (LPS), a component of Gram-negative bacteria, and palmitate (PAL), a free fatty acid. We found that, although both molecules signal through the cell surface protein Toll-like receptor 4 (TLR4), they stimulated the expression of different genes, resulting in specific pro- and anti-inflammatory cellular states for each signal. The effects of the glucocorticoid receptor, which antagonizes LPS signaling, and cyclic AMP–dependent transcription factor 3, which inhibits PAL-induced inflammation, on inflammatory response seemed largely determined by digital on-off events. Furthermore, the quantification of transcriptional variance and signaling entropy enabled the identification of cell state–specific deregulated molecular pathways. These data suggest that the preservation of signaling in distinct cells might confer diversity on macrophage populations essential to maintaining major cellular functions.

A cell-penetrating peptide blocks Toll-like receptor-mediated downstream signaling and ameliorates autoimmune and inflammatory diseases in mice

Toll-like receptors (TLRs) recognize pathogen/damage-associated molecular patterns and initiate inflammatory signaling cascades. Occasionally, overexpression of TLRs leads to the onset of numerous inflammatory diseases, necessitating the development of selective inhibitors to allow a protective yet balanced immune response. Here, we demonstrate that a novel peptide (TIP1) derived from Toll/interleukin-1 receptor (TIR) domain-containing adapter protein inhibited multiple TLR signaling pathways (MyD88-dependent and MyD88-independent) in murine and human cell lines. TIP1 also inhibited NLRP3-mediated IL-1β secretion, as we validated at both the protein and mRNA levels. Biophysical experiments confirmed that TIP1 specifically binds to the BB loop of the TLR4-TIR domain. Animal studies revealed that TIP1 inhibited the secretion of lipopolysaccharide (LPS)-induced proinflammatory cytokines in collagen-induced arthritis (CIA) and kaolin/carrageenan-induced arthritis (K/C) rodent models. TIP1 also rescued animals from sepsis and from LPS-induced kidney/liver damage. Importantly, TIP1 ameliorated the symptoms of rheumatoid arthritis in CIA and K/C rodent models, suggesting that TIP1 has therapeutic potential for the treatment of TLR-mediated autoimmune/inflammatory diseases.

The Traditional Chinese Medicine MLC901 inhibits inflammation processes after focal cerebral ischemia

Inflammation is considered as a major contributor to brain injury following cerebral ischemia. The therapeutic potential of both MLC601/MLC901, which are herbal extract preparations derived from Chinese Medicine, has been reported both in advanced stroke clinical trials and also in animal and cellular models. The aim of this study was to investigate the effects of MLC901 on the different steps of post-ischemic inflammation in focal ischemia in mice. In vivo injury was induced by 60 minutes of middle cerebral artery occlusion (MCAO) followed by reperfusion. MLC901 was administered in post-treatment 90 min after the onset of ischemia and once a day during reperfusion. MLC901 treatment resulted in a reduction in infarct volume, a decrease of Blood Brain Barrier leakage and brain swelling, an improvement in neurological scores and a reduction of mortality rate at 24 hours after MCAO. These beneficial effects of MLC901 were accompanied by an inhibition of astrocytes and microglia/macrophage activation, a drastically decreased neutrophil invasion into the ischemic brain as well as by a negative regulation of pro-inflammatory mediator expression (cytokines, chemokines, matrix metalloproteinases). MLC901 significantly inhibited the expression of Prx6 as well as the transcriptional activity of NFκB and the activation of Toll-like receptor 4 (TLR4) signaling, an important pathway in the immune response in the ischemic brain. MLC901 effects on the neuroinflammation cascade induced by cerebral ischemia probably contribute, in a very significant way, in its potential therapeutic value.

The Complex Interplay between Lipids, Immune System and Interleukins in Cardio-Metabolic Diseases

Lipids and inflammation regulate each other. Early studies on this topic focused on the systemic effects that the acute inflammatory response—and interleukins—had on lipid metabolism. Today, in the era of the obesity epidemic, whose primary complications are cardio-metabolic diseases, attention has moved to the effects that the nutritional environment and lipid derangements have on peripheral tissues, where lipotoxicity leads to organ damage through an imbalance of chronic inflammatory responses. After an overview of the effects that acute inflammation has on the systemic lipid metabolism, this review will describe the lipid-induced immune responses that take place in peripheral tissues and lead to chronic cardio-metabolic diseases. Moreover, the anti-inflammatory effects of lipid lowering drugs, as well as the possibility of using anti-inflammatory agents against cardio-metabolic diseases, will be discussed.

Endotoxemia by Porphyromonas gingivalis Injection Aggravates Non-alcoholic Fatty Liver Disease, Disrupts Glucose/Lipid Metabolism, and Alters Gut Microbiota in Mice

Many risk factors related to the development of non-alcoholic fatty liver disease (NAFLD) have been proposed, including the most well-known of diabetes and obesity as well as periodontitis. As periodontal pathogenic bacteria produce endotoxins, periodontal treatment can result in endotoxemia. The aim of this study was to investigate the effects of intravenous, sonicated Porphyromonas gingivalis (Pg) injection on glucose/lipid metabolism, liver steatosis, and gut microbiota in mice. Endotoxemia was induced in C57BL/6J mice (8 weeks old) by intravenous injection of sonicated Pg; Pg was deactivated but its endotoxin remained. The mice were fed a high-fat diet and administered sonicated Pg (HFPg) or saline (HFco) injections for 12 weeks. Liver steatosis, glucose metabolism, and gene expression in the liver were evaluated. 16S rRNA gene sequencing with metagenome prediction was performed on the gut microbiota. Compared to HFco mice, HFPg mice exhibited impaired glucose tolerance and insulin resistance along with increased liver steatosis. Liver microarray analysis demonstrated that 1278 genes were differentially expressed between HFco and HFPg mice. Gene set enrichment analysis showed that fatty acid metabolism, hypoxia, and TNFα signaling via NFκB gene sets were enriched in HFPg mice. Although sonicated Pg did not directly reach the gut, it changed the gut microbiota and decreased bacterial diversity in HFPg mice. Metagenome prediction in the gut microbiota showed enriched citrate cycle and carbon fixation pathways in prokaryotes. Overall, intravenous injection of sonicated Pg caused impaired glucose tolerance, insulin resistance, and liver steatosis in mice fed high-fat diets. Thus, blood infusion of Pg contributes to NAFLD and alters the gut microbiota.

Potential Medications or Compounds Acting on Toll-like Receptors in Cerebral Ischemia

Background:

Toll-like receptors play an integral role in the process of inflammatory response after ischemic in-jury. The therapeutic potential acting on TLRs is worth of evaluations. The aim of this review was to introduce readers some potential medications or compounds which could alleviate the ischemic damage via TLRs.

Methods:

Research articles online on TLRs were reviewed. Categorizations were listed according to the follows, methods acting on TLRs directly, modulations of MyD88 or TRIF signaling pathway, and the ischemic tolerance induced by the pre-conditioning or postconditioning with TLR ligands or minor cerebral ischemia via acting on TLRs.

Results:

There are only a few studies concerning on direct effects. Anti-TLR4 or anti-TLR2 therapies may serve as promis-ing strategies in acute events. Approaches targeting on inhibiting NF-κB signaling pathway and enhancing interferon regu-latory factor dependent signaling have attracted great interests. Not only drugs but compounds extracted from traditional Chinese medicine have been used to identify their neuroprotective effects against cerebral ischemia. In addition, many re-searchers have reported the positive therapeutic effects of preconditioning with agonists of TLR2, 3, 4, 7 and 9. Several trails have also explored the potential of postconditioning, which provide a new idea in ischemic treatments. Considering all the evidence above, many drugs and new compounds may have great potential to reduce ischemic insults.

Conclusion:

This review will focus on promising therapies which exerting neuroprotective effects against ischemic injury by acting on TLRs.

Inhibition of CCL19 benefits non‑alcoholic fatty liver disease by inhibiting TLR4/NF‑κB‑p65 signaling

Non‑alcoholic fatty liver disease (NAFLD), which affects approximately one‑third of the general population, has become a global health problem. Thus, more effective treatments for NAFLD are urgently required. In the present study, high levels of C‑C motif ligand 19 (CCL19), signaling pathways such as Toll‑like receptor 4 (TLR4)/nuclear factor‑κB (NF‑κB), and proinflammatory factors including interleukin‑6 (IL‑6) and tumor necrosis factor‑α (TNF‑α) were detected in NAFLD patients, thereby indicating that there may be an association between CCL19 and these factors in NAFLD progression. Using a high‑fat diet (HFD), the present study generated a Sprague‑Dawley rat model of NAFLD, which displayed dyslipidemia with increased levels of plasma aspartate aminotransferase, alanine aminotransferase, total cholesterol and triglyceride. Dyslipidemia, liver histopathology and gene expression analyses indicated that the NAFLD model was successfully induced by HFD, and metformin and berberine (BBR) were effective treatments for NAFLD. HFD‑induced CCL19 levels and associated factors were markedly reduced by the two drug treatments. In addition, metformin or BBR alone significantly promoted adenosine monophosphate‑activated protein kinase (AMPK) phosphorylation, which was inhibited by HFD. These results demonstrated that metformin and BBR could improve NAFLD, which may be via the activation of AMPK signaling, and the high expression of CCL19 in NAFLD was significantly reduced by metformin and BBR. It could be inferred that inhibition of CCL19 may be an effective treatment for NAFLD.

Metabolic Regulation of Adipose Tissue Macrophage Function in Obesity and Diabetes

SIGNIFICANCE

Obesity and diabetes are associated with chronic activation of inflammatory pathways that are important mechanistic links between insulin resistance (IR), type 2 diabetes (T2D), and cardiovascular disease pathogenesis. The development of these metabolic diseases is associated with changes in both the number and phenotype of adipose tissue macrophages (ATMs). Emerging lines of evidence have shown that ATMs release proinflammatory cytokines similar to classically activated M1 macrophages, which directly contribute to IR or T2D. In contrast, adipose tissue (AT) from lean healthy individuals contains macrophages with a less inflammatory M2 phenotype. Recent Advances: Recent research has shown that macrophage phenotype is linked to profound changes in macrophage cellular metabolism.

CRITICAL ISSUES

This review focuses on the role of macrophages in AT inflammation and obesity, and the metabolic changes in macrophage function that occur with activation that underpin their role in the pathogenesis of IR and T2D. We highlight current targets for altering macrophage metabolism from both within the field of metabolic disease and AT biology and more widely within inflammatory biology.

FUTURE DIRECTIONS

As our knowledge of macrophage metabolic programming in AT builds, there will be increasing scope for targeting this aspect of macrophage biology as a therapeutic strategy in metabolic diseases. Antioxid. Redox Signal. 29, 297-312.

Neuro- and nephroprotective effect of grape seed proanthocyanidin extract against carboplatin and thalidomide through modulation of inflammation, tumor suppressor protein p53, neurotransmitters, oxidative stress and histology

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Carboplatin and thalidomide induced neuro-nephrotoxicity.

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Carboplatin and thalidomide caused inflammation.

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Carboplatin and thalidomide upregulate tumor suppressor protein p53.

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Carboplatin and thalidomide disturbed cytokine production.

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Neuro-and nephroprotective effect of grape seed proanthocyanidin.

The combination of thalidomide and carboplatin is one of the most potent chemotherapeutic strategies for the treatment of cancer. However, limited studies have been conducted on the neurotoxicity and nephrotoxicity of both chemotherapeutic agents. The aim of our study was to assess the toxicity of thalidomide and carboplatin combination on brain and kidney and investigate the protective effect of grape seed proanthocyanidin extract (GSPE). Thalidomide and carboplatin induced up-regulation of the expression of p53, tumor necrosis factor-α and interleukin-6 in brain and kidney. Acetylcholinesterase, dopamine and serotonin were decreased and norepinephrine was increased. Thiobarbituric acid reactive substances, nitric oxide, lipid profile, bilirubin and creatinine were elevated, while antioxidants enzymes (GST, GPX, CAT and SOD), total antioxidant capacity and the levels of glutathione were decreased. A microscopic examination showed shrinkage of capillaries, degeneration with pyknotic nuclei, loss of normal structure and neuronal degeneration. GSPE co-treatment with thalidomide and carboplatin reduced their brain and renal damage, oxidative stress, diminished cytokines, p53, neurotransmitters and biochemical parameters, and inhibited brain and renal cell apoptosis. It can be concluded that, the protective effects of GSPE against thalidomide and carboplatin induced-brain and renal damage was associated with the minimization of oxidative stress.

Strategy to targeting the immune resistance and novel therapy in colorectal cancer

Assessing the CRC subtypes that can predict the outcome of colorectal cancer (CRC) in patients with immunogenicity seems to be a promising strategy to develop new drugs that target the antitumoral immune response. In particular, the disinhibition of the antitumoral T‐cell response by immune checkpoint blockade has shown remarkable therapeutic promise for patients with mismatch repair (MMR) deficient CRC. In this review, the authors provide the update of the molecular features and immunogenicity of CRC, discuss the role of possible predictive biomarkers, illustrate the modern immunotherapeutic approaches, and introduce the most relevant ongoing preclinical study and clinical trials such as the use of the combination therapy with immunotherapy. Furthermore, this work is further to understand the complex interactions between the immune surveillance and develop resistance in tumor cells. As expected, if the promise of these developments is fulfilled, it could develop the effective therapeutic strategies and novel combinations to overcome immune resistance and enhance effector responses, which guide clinicians toward a more “personalized” treatment for advanced CRC patients.

Exploring Immune Development in Infants With Moderate to Severe Atopic Dermatitis

Background

Atopic dermatitis (AD) is the most common chronic inflammatory skin disease in infancy with a complex pathology. In adults, the clinical severity of AD has been associated with increases in T helper cell type (Th) 2, Th22, and Th17 serum markers, including high levels of CC chemokine ligand (CCL) 17 and CCL22 chemokines.

Objective

To explore the possible association between serum chemokine levels and AD severity in infants with moderate-to-severe AD and elevated immunoglobulin E (IgE).

Subjects and methods

Serum samples (n = 41) obtained from a randomized, double-blind, and clinical dietary intervention study were used to study biomarkers in infants with AD. Baseline- and post-intervention samples (4 months) were used, six chemokines and nine ratios thereof were analyzed using Luminex and correlated to AD severity. In the initial study, the infants were randomized to receive extensively hydrolyzed whey-based formula without (control) or with short-chain galacto-oligosaccharides/long-chain fructo-oligosaccharides (9:1) and Bifidobacterium breve M-16V (active).

Results

31 Infants up to 11 months of age, with an objective-SCORAD score (oSCORAD) ≥ 20 and elevated total-IgE and/or specific-IgE levels were included. In time, the median oSCORAD decreased in both groups by −8 (control, p < 0.05; active, p < 0.01). Irrespective of dietary intervention, several changes in Th2 chemokines (CCL17 and CCL22), inflammatory chemokine (CCL20), and the Th1 chemokine, CXC chemokine ligand (CXCL) 9, were detected over time. Overall CCL17 correlated to oSCORAD (r = 0.446, p < 0.01). After 4 months of dietary intervention, CXCL9 was higher (p < 0.01) in the active group compared with control [active, 2.33 (1.99–2.89); controls, 1.95 (1.77–2.43) log 10 median (range)]. In addition, a reduction in Th2/Th1 chemokine ratios for CCL17/CXCL9, CCL22/CXCL9, CCL20/CXCL10, and CCL20/CXCL11 was detected associated with the active intervention.

Conclusion

While this study is small and exploratory in nature, these data contribute to immune biomarker profiling and understanding of AD in infants.

Effect of acupuncture on the TLR2/4-NF-κB signalling pathway in a rat model of traumatic brain injury

Objective

To study the effect of acupuncture on the TLR2/4-NF-κB signalling pathway in the cortex of Sprague-Dawley rats following traumatic brain injury (TBI), and investigate the possible mechanism underlying the effects of acupuncture on scar repair.

Methods

TBI was established using Feeney’s free-falling epidural percussion model. In total, 108 rats were randomly divided into a normal group (n=18), untreated TBI model group (TBI group, n=36) and manual acupuncture-treated TBI group (TBI+MA, n=36). Each group of rats was subdivided into three time groups: 3-day (3d), 7-day (7d) and 14-day (14d). No treatment was given to rats in the normal and TBI groups. The TBI+MA group received manual acupuncture at GV20, GV26, GV16 through GV15, and bilateral LI4. mRNA expression of TLR2, TLR4, NF-κB and protein in the rat cortices was quantified using real-time fluorescence quantitative polymerase chain reaction (qPCR) and Western blot analyses.

Results

The modified neurological severity score (mNSS) scores of the TBI+MA group were improved compared with baseline scores 12 hours after modelling, and improved at 7d and 14d compared with the TBI group (P<0.05), while the score of the TBI group did not improve until 14d compared to baseline. mRNA and protein expression of TLR2, TLR4 and NF-κB in the TBI group were higher than the normal group at 3d (P<0.05), reached a peak at 7d, then began to decrease at 14d. mRNA and protein expression of TLR2, TLR4 and NF-κB were higher in the TBI+MA group compared with the TBI group at 3d (P<0.05), were significantly down-regulated at 7d (P<0.01), and decreased to normal levels at 14d.

Conclusions

Acupuncture has a bidirectional regulatory effect on the TLR2/4-NF-κB signalling pathway-related genes TLR2, TLR4 and NF-κB in the TBI rat cortex, promoting their expression in the early stage and inhibiting it in the later stage.

Toll like receptor 3 as an immunotherapeutic target for KRAS mutated colorectal cancer

New therapeutic interventions are essential for improved management of patients with metastatic colorectal cancer (mCRC). This is especially critical for those patients whose tumors harbor a mutation in the KRAS oncogene (40-45% of all patients). This patient cohort is excluded from receiving anti-EGFR monoclonal antibodies that have added a significant therapeutic benefit for KRAS wild type CRC patients. Reovirus, a double stranded (ds) RNA virus is in clinical development for patients with chemotherapy refractory KRAS mutated tumors. Toll Like Receptor (TLR) 3, a member of the toll like receptor family of the host innate immune system is the pattern recognition motif for dsRNA pathogens. Using TLR3 expressing commercial HEK-Blue™-hTLR3 cells we confirm that TLR3 is the host pattern recognition motif responsible for the detection of reovirus. Further, our investigation with KRAS mutated HCT116 cell line showed that effective expression of host TLR3 dampens the infection potential of reovirus by mounting a robust innate immune response. Down regulation of TLR3 expression with siRNA improves the anticancer activity of reovirus. In vivo experiments using human CRC cells derived xenografts in athymic mice further demonstrate the beneficial effects of TLR3 knock down by improving tumor response rates to reovirus. Strategies to mitigate the TLR3 response pathway can be utilized as a tool towards improved reovirus efficacy to specifically target the dissemination of KRAS mutated CRC.

Neuroprotective effect of a novel gastrodin derivative against ischemic brain injury: involvement of peroxiredoxin and TLR4 signaling inhibition

The inhibition of extracellular inflammatory peroxiredoxin (Prx) signaling appears to be a potential therapeutic strategy for neuroinflammatory injury after acute ischemic stroke. Gastrodin (Gas) is a phenolic glycoside that is used for the treatment of cerebral ischemia, accompanied by regulation of the autoimmune inflammatory response. The present study investigated the neuroprotective effects of Gas and its derivative, Gas-D, with a focus on the potential mechanism associated with inflammatory Prx-Toll-like receptor 4 (TLR4) signaling. Gas-D significantly inhibited Prx1-, Prx2-, and Prx4-induced inflammatory responses in RAW264.7 macrophages and H2O2-mediated oxidative injury in SH-SY5Y nerve cells. In rats, intraperitoneal Gas-D administration 10 h after reperfusion following 2-h middle cerebral artery occlusion (MCAO) ameliorated neurological deficits, brain infarction, and neuropathological alterations, including neuron loss, astrocyte and microglia/macrophage activation, T-lymphocyte invasion, and lipid peroxidation. Delayed Gas-D treatment significantly inhibited postischemic Prx1/2/4 expression and spillage, TLR4 signaling activation, and inflammatory mediator production. In contrast, Gas had no significant effects in either cell model or in MCAO rats under the same conditions. These results indicate that Gas-D may be a drug candidate with an extended therapeutic time window that blocks inflammatory responses and attenuates the expression and secretome of inflammatory Prxs in acute ischemic stroke.

The potent suppressive effect of β-d-mannuronic acid (M2000) on molecular expression of the TLR/NF-kB Signaling Pathway in ankylosing spondylitis patients

Ankylosing spondylitis (AS) is a chronic inflammatory rheumatic disease characterized by the inflammation of sacroiliac joints and axial skeleton. A combination of genetic, environmental and immunological factors are involved in AS's pathogenesis. TLRs are type I transmembrane glycoproteins that play a crucial role in the innate immune responses against invading pathogens. Observational studies have demonstrated a possible association between TLR dysregulation and AS. The β-d-mannuronic acid (M2000), as a novel NSAID with immunosuppressive property, has shown an inhibitory effect on Toll-like receptor (TLR) 2, 4 signaling in HEK293 cells. In the present study, we investigated the gene expression of Myd88, IKB-alpha, NF-kB and MAPK14 (genes of the TLR/NF-kB Signaling Pathway) in AS patients in comparison to healthy subjects and also the effect of β-d-mannuronic acid on disease activity and mRNA expression of these molecules in affected patients. We showed for the first time that the gene expression level of Myd88, IKB-alpha, NF-kB and MAPK14 was higher in AS patients in comparison to healthy subjects. Moreover we confirmed that the β-d-mannuronic acid not just reduced significantly the disease activity of AS individuals compared to placebo, but also it could significantly decrease the expression level of genes associated with TLR/NF-kB Signaling Pathway in treated patients with M2000. These results may provide a new therapeutic approach to attenuate inflammatory responses in AS patients, (Identified; IRCT 2013062213739N1).

Applying nanomedicine in maladaptive inflammation and angiogenesis

Inflammation and angiogenesis drive the development and progression of multiple devastating diseases such as atherosclerosis, cancer, rheumatoid arthritis, and inflammatory bowel disease. Though these diseases have very different phenotypic consequences, they possess several common pathophysiological features in which monocyte recruitment, macrophage polarization, and enhanced vascular permeability play critical roles. Thus, developing rational targeting strategies tailored to the different stages of the journey of monocytes, from bone marrow to local lesions, and their extravasation from the vasculature in diseased tissues will advance nanomedicine. The integration of in vivo imaging uniquely allows studying nanoparticle kinetics, accumulation, clearance, and biological activity, at levels ranging from subcellular to an entire organism, and will shed light on the fate of intravenously administered nanomedicines. We anticipate that convergence of nanomedicines, biomedical engineering, and life sciences will help to advance clinically relevant therapeutics and diagnostic agents for patients with chronic inflammatory diseases.

Uric Acid Induces Cognitive Dysfunction through Hippocampal Inflammation in Rodents and Humans

Uric acid (UA) is a purine metabolite that in most mammals is degraded by the hepatic enzyme uricase to allantoin. Epidemiological studies have shown that an elevated UA level predicts the development of cognition and memory deficits; however, there is no direct evidence of this relationship, and the underlying mechanism is largely undefined. Here, we show that a high-UA diet triggers the expression of proinflammatory cytokines, activates the Toll-like receptor 4 (TLR4)/nuclear factor (NF)-κB pathway, and increases gliosis in the hippocampus of Wistar rats. We, subsequently, identify a specific inhibitor of NF-κB, BAY11-7085, and show that stereotactic injections of the inhibitor markedly ameliorate UA-induced hippocampal inflammation and memory deficits in C57BL/6 mice. We also found that NF-κB is activated in the primary cultured hippocampal cells after UA administration. Additionally, C57BL/6 mice that lack TLR4 are substantially protected against UA-induced cognitive dysfunction, possibly due to a decrease in inflammatory gene expression in the hippocampus. Importantly, magnetic resonance imaging confirms that hyperuricemia in rats and humans is associated with gliosis in the hippocampus. Together, these results suggest that UA can cause hippocampal inflammation via the TLR4/NF-κB pathway, resulting in cognitive dysfunction. Our findings provide a potential therapeutic strategy for counteracting UA-induced neurodegeneration.

SIGNIFICANCE STATEMENT

This work demonstrates that a high-uric acid (UA) diet triggers the expression of proinflammatory cytokines, activates the Toll-like receptor 4 (TLR4)/nuclear factor (NF)-κB pathway, and increases gliosis in the hippocampus of Wistar rats. Inhibition of the NF-κB signaling pathway markedly ameliorates UA-induced hippocampal inflammation and cognitive dysfunction in C57BL/6 mice. TLR4-knock-out mice are substantially protected against UA-induced cognitive dysfunction, possibly due to a decrease in inflammatory gene expression in the hippocampus. Moreover, magnetic resonance imaging confirms that hyperuricemia in rats and humans are associated with gliosis in the hippocampus. Together, this study suggests that there is an important link between UA-induced cognitive dysfunction and hippocampal inflammation in rodents and humans, which may have remarkable implications in the treatment of UA-induced neurodegeneration.

Toll-like receptor 2 antagonists identified through virtual screening and experimental validation

Toll-like receptor 2 (TLR2) antagonists are key therapeutic targets because they inhibit several inflammatory diseases caused by surplus TLR2 activation. In this study, we identified two novel nonpeptide TLR2 antagonists, C11 and C13, through pharmacophore-based virtual screening. At 10 μm, the level of interleukin (IL)-8 inhibition by C13 and C11 in human embryonic kidney TLR2 overexpressing cells was comparable to the commercially available TLR2 inhibitor CU-CPT22. In addition, C11 and C13 acted in mouse macrophage-like RAW 264.7 cells as TLR2-specific inhibitors and did not suppress the tumor necrosis factor-α induction by TLR3 and TLR4 activators. Moreover, the two identified compounds bound directly to the human recombinant TLR2 ectodomain, during surface plasmon resonance analysis, and did not affect cell viability in a 3-(4,5-dimethylthiazol-2-yl)-5(3-carboxymethonyphenol)-2-(4-sulfophenyl)-2H-tetrazolium assay. In total, two virtually screened molecules, C11 and C13, were experimentally proven to be effective as TLR2 antagonists, and thus will provide new insights into the structure of TLR2 antagonists, and pave the way for the development of TLR2-targeted drug molecules.