Toll-like Receptor Research Articles

TLR priming licenses NAIP inflammasome activation by immunoevasive ligands

NLR family, apoptosis inhibitory proteins (NAIPs) detect bacterial flagellin and structurally related components of bacterial type III secretion systems (T3SS), and recruit NLR family CARD domain containing protein 4 (NLRC4) and caspase-1 into an inflammasome complex that induces pyroptosis. NAIP/NLRC4 inflammasome assembly is initiated by the binding of a single NAIP to its cognate ligand, but a subset of bacterial flagellins or T3SS structural proteins are thought to evade NAIP/NLRC4 inflammasome sensing by not binding to their cognate NAIPs. Unlike other inflammasome components such as NLRP3, AIM2, or some NAIPs, NLRC4 is constitutively present in resting macrophages and not known to be induced by inflammatory signals. Here, we demonstrate that Toll-like receptor (TLR)-dependent p38 mitogen-activated protein kinase signaling up-regulates NLRC4 transcription and protein expression in murine macrophages, which licenses NAIP detection of evasive ligands. In contrast, TLR priming in human macrophages did not up-regulate NLRC4 expression, and human macrophages remained unable to detect NAIP-evasive ligands even following priming. Critically, ectopic expression of either murine or human NLRC4 was sufficient to induce pyroptosis in response to immunoevasive NAIP ligands, indicating that increased levels of NLRC4 enable the NAIP/NLRC4 inflammasome to detect these normally evasive ligands. Altogether, our data reveal that TLR priming tunes the threshold for the murine NAIP/NLRC4 inflammasome to enable inflammasome responses against immunoevasive or suboptimal NAIP ligands. These findings provide insight into species-specific TLR regulation of NAIP/NLRC4 inflammasome activation.

Lycopene alleviates chemotherapy-induced mucositis via enhancing intestinal barrier function and attenuating TLR4/MyD88/NF-κB signaling cascade

5-Fluorouracil (5-FU) is one of the most common chemotherapeutic agents used in treating solid tumors. Lycopene is a natural exogenous carotenoid with antioxidant, anti-inflammatory, immunomodulatory, and anticancer activity. Intestinal mucositis is a commonly encountered complication for chemotherapy. However, effective or preventive treatment for this common complication is still need to be elucidated. The current study aimed to appraise the effect of lycopene on 5-FU-induced intestinal mucositis (FUIIM). Twenty-eight male rats were divided randomly and equally into four groups: control, lycopene, FUIIM, and 5-FU + lycopene groups. Parameters for mucosal barrier integrity, redox and inflammatory status, and apoptosis were immunoassayed in addition to histological assessment. Decreased body weight, significantly impaired redox status, increased caspase 3 level, toll-like receptor (TLR) 4 level, myd88 and NF-κB expression. However, decreased Bcl-2, and Ki-67 expression were detected in 5-FUIIM group. Furthermore, impairment in intestinal barrier integrity, represented by decreased Occludin and claudin1 levels with impaired histological features and ultrastructural features, were also detected. Meanwhile, lycopene co-administration protected against weight loss, heightened oxidative stress, apoptosis, inflammation, disturbed intestinal barrier integrity, and impaired histological and ultrastructure features. In conclusion, lycopene significantly improved intestinal mucositis, barrier integrity and gut toxicity induced by 5-FU in rats.

Pharmacodynamic effects and exploratory efficacy of afimetoran, a TLR7/8 inhibitor, in patients with cutaneous lupus erythematosus

Background: Cutaneous lupus erythematosus (CLE) is a chronic inflammatory skin condition occurring alone or as a manifestation of systemic lupus erythematosus (SLE). There is an unmet need for safe and effective CLE-focused treatments. Afimetoran is an investigational, first-in-class, potent oral inhibitor of toll-like receptors (TLRs) 7/8. Given the involvement of TLRs 7/8 in SLE, afimetoran may have therapeutic potential for CLE. A phase 1b randomized, double-blind, placebo-controlled study (NCT04493541) demonstrated preliminary safety and efficacy of afimetoran in patients with active CLE. We assessed the pharmacodynamics, safety, and efficacy of afimetoran and its impact on CLE pathobiology. Methods: Patients aged 18–65 years with SLE and cutaneous manifestations by EULAR/ACR 2019 classification criteria or biopsy-proven CLE, and modified CLE Disease Area and Severity Index-Activity (CLASI-A) score ≥6, were randomized 2:1 to once-daily afimetoran (30 mg) or placebo for 16 weeks with a 4-week post-treatment follow-up period. The primary endpoints were safety and tolerability; efficacy was exploratory. Transcriptomics and cytokine analyses were performed using peripheral whole blood and serum, respectively, at baseline (pre-dose) and each study visit (weeks 1, 2, 4, 8, 12, 16, and 20 [post-dose]). Statistical analyses compared data from the 13 randomized patients with thirteen age-, ethnicity-, and gender-matched healthy volunteers. Treatment responses were evaluated longitudinally in each treatment arm. The dataset was analyzed using a linear regression model. Gene set variation analysis (GSVA) was performed for pathway enrichment. Results: 13 patients with CLE were randomized (afimetoran, n=8; placebo, n=5); 12 patients completed 16 weeks of treatment and 1 discontinued after 6 weeks due to COVID-19. Compared with placebo, afimetoran demonstrated a favorable safety profile with no serious adverse events, and showed a greater reduction in CLASI-A scores as early as week 4, which persisted to week 20. Improvement in the molecular disease profile was rapid (week 1), sustained through the 16-week treatment period, and the 4-week post-treatment follow-up period. Expression of interferon (IFN) pathway genes was significantly reduced with afimetoran compared with baseline (ΔGSVA enrichment score [ES]=1.57, P<0.0001) and placebo (ΔGSVA ES=0.56, P<0.01); this effect was maintained through week 16 and ≥4 weeks post-treatment. Expression of TLR7 and TLR8 pathway genes and key cytokines (interleukin [IL]-6, tumor necrosis factor α, IL-18, IFNγ, macrophage inflammatory protein-1 alpha [CCL3/MiP1α] or beta [CCL4/MiP1β]) were greatly reduced with afimetoran treatment. GSVA demonstrated robust pharmacodynamic activity on immune cell populations, including immature and activated dendritic cells, macrophages, and inflammatory pathway signatures. Conclusion: In patients with CLE, afimetoran was safe, well tolerated, and demonstrated durable efficacy beyond the treatment period. Afimetoran’s clinical effects and potent pharmacodynamic impact on the molecular disease profile suggest a substantial therapeutic benefit for patients with CLE.

Abstract C003: Outer membrane vesicles from Bacteroides fragilis contain coding and non-coding small RNA species that modulate inflammatory signaling in intestinal epithelial cells

Abstract Alterations to the community structure and function of the microbiome are associated with changes to host physiology, including immune responses. However, the contribution of microbial-derived RNAs carried by outer membrane vesicles (OMVs) to host immune responses remains unclear. This paper investigates the role of OMVs and OMV-associated small RNA (sRNA) species from pathogenic and commensal Bacteroides fragilis (ETBF and NTBF respectively) in eliciting different immune responses in intestinal epithelial cells. To distinguish the differences in the sRNA profiles of both strains and their OMVs, small RNA-seq was conducted, and identified enrichment of discrete sRNA species in OMVs that were also differentially expressed between the two strains. To understand the effects of OMVs on pattern recognition receptors, Toll-like receptor (TLR) reporter cells were treated with OMVs, and activation of TLRs 2, 3, 4, and 7 were observed. Treatment of Caco-2 and HT29-MTX cells with OMVs demonstrated increased expression of IL-8. Surprisingly, we discovered that degradation of RNase-accessible RNAs within ETBF OMVs, but not NTBF OMVs, resulted in vesicles with enhanced capacity to stimulate IL-8 expression, indicating that these extravesicular RNAs exert an immunosuppressive effect. This suggests a dual role for OMV-associated RNAs in modulating host immune responses, with implications for both bacterial pathogenesis and therapeutic applications. Citation Format: Aadil Sheikh, Colin Scano, Julia Xu, Tolulope Ojo, Jessica M. Conforti, Kayla L. Haberman, Bryan King, James Lotter, Alysia Martinez, Harry Ojeas, Michelle Pujol, Juli Watkins, Emily Lin, Bernd Zechmann, Amanda Sevcik, Christie Sayes, Elyssia S Gallagher, Joshua Mell, Garth Ehrlich, Joseph H Taube, K. Leigh Greathouse. Outer membrane vesicles from Bacteroides fragilis contain coding and non-coding small RNA species that modulate inflammatory signaling in intestinal epithelial cells [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr C003.

A novel role of peroxiredoxin 2 in diabetic kidney disease progression by activating the classically activated macrophages.

Diabetic kidney disease (DKD) is the main cause of deaths due to diabetes mellitus (DM). Due to the complexity of its onset, it is difficult to achieve accurate prevention and treatment. The classically activated macrophage (M1) polarization is a crucial proinflammatory mechanism of DKD, while the interaction and cascade effects of oxidative stress and inflammatory response remain to be elucidated. A urine proteomic analysis of patients with DM indicated that peroxiredoxin 2 (PRDX2) had the higher abundance in DKD. We recently found that PRDX of parasitic protozoa Entamoeba histolytica, which was similar to human PRDX2 in amino acid sequence and spatial structure, could activate the inflammatory response of macrophages through toll-like receptor 4 (TLR4). Hence, our study was designed to explore the role of PRDX2 in chronic inflammation during DKD. Combined with in vivo and in vitro experiments, results showed that the PRDX2 was positively correlated with DKD progression and upregulated by high glucose or recombinant tumor necrosis factor-α in renal tubular epithelial cells; Besides, recombinant PRDX2 could promote M1 polarization of macrophages, and enhance the migration as well as phagocytic ability of macrophages through TLR4. In summary, our study has explored the novel role of PRDX2 in DKD to provide a basis for further research on the diagnosis and treatment of DKD.

Eradication of proliferative verrucous leukoplakia with toll-like receptor 7 agonist (topical imiquimod): a case report

Proliferative verrucous leukoplakia (PVL) is an aggressive and distinct type of oral precancerous lesion characterized by warty surfaced white plaque diffusely involving oral mucosa. Surgical excision is the treatment of choice. However, PVL has persistent and recurrent growth patterns, requiring multiple surgical procedures. Surgical intervention is especially challenging if PVL extends between teeth limiting access. These interproximally located lesions have a high propensity to undergo malignant transformation. We report a case of a 53-year-old man with recurrent PVL diffusely covering the maxillary and mandibular gingiva. Despite complete surgical excisions, PVL recurred, and a focal area in the interproximal mandibular gingiva progressed to invasive squamous cell carcinoma requiring marginal resection. The remaining PVL areas were treated with topical imiquimod (toll-like receptor 7 agonist) for six months, resulting in complete clinical and histological resolution. Topical agents can cover a larger surface area and penetrate in between interproximal areas. Importantly, it allows for maximal local exposure with minimal systemic toxicity, essential for long-term treatment and prophylactic use of the agent to prevent relapse.

Chinese herbal medicine, Tongxieyaofang, alleviates diarrhea via gut microbiota remodeling: evidence from network pharmacology and full-length 16S rRNA gene sequencing

BackgroundTongxieyaofang (TXYF) was a traditional Chinese medicine (TCM) formula for the treatment of diarrhea with liver stagnation and spleen deficiency syndrome, but the potential targets and mechanisms have not been fully clarified. This study aims to explore the potential mechanisms of TXYF in alleviating diarrhea using network pharmacology and full-length 16S rRNA gene sequencing.MethodsNetwork pharmacology was applied to identify bioactive compounds and potential targets involved in the role of TXYF in alleviating diarrhea. Meanwhile, a model of diarrhea with liver stagnation and spleen deficiency syndrome was constructed by intragastric administration of Folium senna extract combined with restraint and tail pinch stress. The effect of TXYF on intestinal mucosal microbiota of diarrhea mice was analyzed by full-length 16S rRNA gene sequencing.ResultsNetwork pharmacology analysis showed that kaempferol, wogonin, naringenin, and nobiletin were compounds associated with the efficacy of TXYF. TXYF may alleviate diarrhea via multiple BPs and pathways, including TNF signaling pathway, IL-17 signaling pathway, and Toll-like receptor signaling pathway, which are involved in TCM-gut microbiota-host interactions. Then, we found that TXYF administration reshaped the diversity and composition of the intestinal mucosal microbial community of diarrhea mice. Lactobacillus, primarily Lactobacillus johnsonii, was enriched by the administration of TXYF. After TXYF administration, the abundance of Lactobacillus, particularly Lactobacillus johnsonii, was enriched.ConclusionOral administration of TXYF may alleviate diarrhea through remodeling intestinal mucosal microbiota. Promoting the colonization of beneficial commensal bacteria in the intestinal mucosa through gut microbiota-host interactions may be a potential mechanism of TXYF in the treatment of diarrhea.

Berberine Mitigates Sepsis-Associated Acute Kidney Injury in Aged Rats by Preserving Mitochondrial Integrity and Inhibiting TLR4/NF-κB and NLRP3 Inflammasome Activations

Sepsis-associated acute kidney injury (SA-AKI) presents a severe challenge in the elderly due to increasing incidence, high mortality, and the lack of specific effective treatments. Exploring novel and secure preventive and/or therapeutic approaches is critical and urgent. Berberine (BBR), an isoquinoline alkaloid with anti-inflammatory, antioxidant, and immunomodulatory properties, has shown beneficial effects in various kidney diseases. This study examined whether BBR could protect against SA-AKI in aged rats. Sepsis was induced in 26-month-old male Wistar rats by cecal ligation and puncture (CLP), either with or without BBR pretreatment. CLP induction led to SA-AKI, as indicated by elevated serum levels of malondialdehyde, tumor necrosis factor-alpha, urea nitrogen, creatinine, and neutrophil gelatinase-associated lipocalin (NGAL), along with histopathological features of kidney damage. Key indicators of kidney oxidative stress, mitochondrial dysfunction, apoptosis, and activations of the Toll-like receptor 4/nuclear factor-kappa B (TLR4/NF-κB) signaling, including the nucleotide-binding domain, leucine-rich-containing family, and pyrin domain-containing-3 (NLRP3) inflammasome pathway, were also elevated following CLP induction. BBR pretreatment substantially mitigated these adverse effects, suggesting that it protects against SA-AKI in aged rats by reducing oxidative stress, preserving mitochondrial integrity, and inhibiting key inflammatory pathways. These findings highlight the potential of BBR as a therapeutic agent for managing SA-AKI in elderly populations.

SHR-1806, a robust OX40 agonist to promote T cell-mediated antitumor immunity

ABSTRACT Anti-CTLA-4 and anti-PD-1/PD-L1 antibodies have significantly revolutionized cancer immunotherapy. However, the persistent challenge of low patient response rates necessitates novel approaches to overcome immune tolerance. Targeting immunostimulatory signaling may have a better chance of success for its ability to enhance effector T cell (Teff) function and expansion for antitumor immunity. Among various immunostimulatory pathways, the evidence underscores the potential of activating OX40-OX40L signaling to enhance CD8+ T cell generation and maintenance while suppressing regulatory T cells (Tregs) within the tumor microenvironment (TME). In this study, we introduce a potent agonistic anti-OX40 antibody, SHR-1806, designed to target OX40 receptors on activated T cells and amplify antitumor immune responses. SHR-1806 demonstrates a high affinity and specificity for human OX40 protein, eliciting FcγR-mediated agonistic effects, T cell activation, antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) activities in vitro. In human OX40 knock-in mice bearing MC38 tumor, SHR-1806 shows a trend toward a higher potency than the reference anti-OX40 antibody produced in-house, GPX4, an analog of pogalizumab, the most advanced drug candidate developed by Roche. Furthermore, SHR-1806 displays promising anti-tumor activity alone or in combination with toll-like receptor 7 (TLR7) agonist or PD-L1 inhibitor in mouse models. Evaluation of SHR-1806 in rhesus monkeys indicates a favorable safety profile and typical pharmacokinetic characteristics. Thus, SHR-1806 emerges as a robust OX40 agonist with promising therapeutic potential.

TLR10 expression in unswitched memory B associates with the disease activity of patients with systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is characterized by impaired B-cell function and a distinct B-cell phenotype. Toll-like receptor (TLR) 10 is highly expressed in human B cells and can regulate B-cell activation. Here, we examined the variations in TLR10 expression across B-cell subpopulations and its impact on the disease activity in SLE patients. Thirty-one patients with stable SLE, 30 patients with active SLE, and 28 healthy controls (HCs) were recruited. Flow cytometry was performed to assess the prevalence of B-cell subpopulations and their TLR10 expression. The diagnostic value of unswitched memory B cells (UMB) and double-negative B cells (DNB) in relation to disease activity was determined. The correlations between TLR10 expressions in B-cell subpopulations and disease activity were further evaluated, respectively. Compared with the HCs, the stable patients exhibited significantly reduced Naive B proportion and elevated switched memory B and DNB proportion, while active patients presented markedly decreased UMB and increased DNB proportion. Furthermore, the receiver operating characteristics analysis revealed that UMB was more reliable than DNB in diagnosing SLE disease activity. Among the B-cell subsets, only the TLR10 expression in UMB was notably diminished in SLE patients, particularly in active patients. Importantly, TLR10 expression in UMB was negatively correlated with the disease activity. UMB could serve as a promising biomarker for SLE disease activity, and the TLR10 expression in UMB was negatively correlated with the activity of SLE patients, suggesting that TLR10 might be involved in the disease progression of SLE by regulating the UMB function. Key Points • Active SLE patients exhibited reduced unswitched memory B cells and increased double-negative B cell proportions in blood. • Unswitched memory B cells are better predictors of disease activity in SLE than double-negative B cells. • TLR10 expression in unswitched memory B cells is markedly diminished in SLE patients. • TLR10 expression in unswitched memory B cells is negatively associated with SLE disease activity.

The multifaceted anticancer potential of luteolin: involvement of NF-κB, AMPK/mTOR, PI3K/Akt, MAPK, and Wnt/β-catenin pathways.

Cancer is the predominant and major cause of fatality worldwide, based on the different types of cancer. There is a limitation in the current treatment. So we need better therapeutic agents that counteract the progression and development of malignant tumours. Plant-derived products are closely related and useful for human health. Luteolin is a polyphenolic flavonoid bioactive molecule that is present in various herbs, vegetables, fruits, and flowers and exhibits chemoprotective and pharmacological activity against different malignancies. To offer innovative approaches for the management of various cancers, we present a comprehensive analysis of the latest discoveries on luteolin. The aim is to inspire novel concepts for the development of advanced pharmaceuticals targeting cancer and search specifically targeted reviews and research articles published from January 1999 to January 2024 that investigated the application of luteolin in various cancer management. A thorough literature search utilizing the keywords "luteolin" "Signalling Pathway" "cancer" and nanoparticles was performed in the databases of Google Scholar, Web of Science, SCOPUS, UGC care list and PubMed. Through the compilation of existing research, we have discovered that luteolin possesses several therapeutic actions against various cancer via a signaling pathway involving the of NF-κB regulation, AMPK/mTOR, toll-like receptor, Nrf-2, PI3K/Akt MAPK and Wnt/β-catenin and their underlying mechanism of action has been well understood. This review intended to completely integrate crucial information on natural sources, biosynthesis, pharmacokinetics, signaling pathways, chemoprotective and therapeutic properties against various cancers, and nanoformulation of luteolin.

Effects of adding niacinamide to diets with normal and low protein levels on the immunity, antioxidant, and intestinal microbiota in growing-finishing pigs.

This study aimed to investigate the effects of nicotinamide (NAM) applied to diets with different crude protein levels on immune function, antioxidant capacity, and intestinal flora in growing-finishing pigs. Forty barrows (37.0 ± 1.0 kg) were randomly allocated to one of four dietary treatments (n = 10 per group). The diets in the two phases consisted of a basal diet with 30 mg/kg NAM, a basal diet with 360 mg/kg NAM, a low-protein diet with 30 mg/kg NAM, and a low-protein diet with 360 mg/kg NAM. The results showed that dietary addition of 360 mg/kg NAM decreased IL-12, malondialdehyde, IgG and IgM contents in the plasma and increased total superoxide dismutase activity and total antioxidant capacity in the colonic mucosa (P < 0.05). Supplementing the diet with 360 mg/kg NAM increased mRNA expression of the nucleotide-binding oligomerization domain containing 2 and nuclear factor erythroid 2-related factor 2 and protein expression of nuclear factor kappa-B and toll-like receptor 4 in the colonic mucosa (P < 0.05). The concentrations of acetic acid and butyric acid in the colonic contents and the abundance of Actinobacteriota in the colon at the phylum level were significantly decreased by feeding low-protein diets (P < 0.05). Additionally, the addition of 360 mg/kg NAM to diets increased (P < 0.05) the Sobs, Ace, and Chao indices of colonic microorganisms in pigs. Overall, the rational use of NAM can improve inflammatory status, enhance antioxidant capacity and intestinal barrier function, and increase colonic microbial diversity in growing-finishing pigs.

Isobutyrate exerts a protective effect against liver injury in a DSS-induced colitis by inhibiting inflammation and oxidative stress.

Short-chain fatty acids have been reported to have anti-inflammatory and antioxidant functions; whether isobutyrate, a short-chain fatty acid, is protective against liver injury in a dextran sodium sulfate (DSS)-induced colitis and its molecular mechanism is unknown. In this study, DSS was used to induce a liver injury from a colitis model in piglets, which was expected to prevent and alleviate DSS-induced liver injury by feeding sodium isobutyrate in advance. The results showed that sodium isobutyrate could restore DSS-induced histopathological changes in the liver, inhibit the activation of the toll-like receptor 4/myeloid differentiation primary response 88/nuclear factor kappa-B signaling pathway, and then reduce the DSS-induced release of pro-inflammatory cytokines tumor necrosis factor-α, interleukin 1β, and interleukin 6, reducing inflammatory response. Moreover, we found that sodium isobutyrate could play an antioxidant and apoptosis-reducing role by maintaining reduced mitochondrial function. In conclusion, sodium isobutyrate has a preventive and protective effect on liver injury in a DSS-induced colitis. There is a potential application prospect for it in treating ulcerative-colitis-induced liver injuries. © 2024 Society of Chemical Industry.

Systemic chemokine-modulatory regimen combined with neoadjuvant chemotherapy in patients with triple-negative breast cancer

BackgroundHigher cytotoxic T lymphocyte (CTL) numbers in the tumor microenvironment (TME) predict pathologic complete response (pCR) to neoadjuvant chemotherapy (NAC) and positive long-term outcomes in triple-negative breast cancer (TNBC). pCR...

Epimedium polysaccharides ameliorate ulcerative colitis by inhibiting oxidative stress and regulating autophagy.

Epimedium polysaccharide (EPS) is a bioactive compound derived from the traditional Chinese herb Epimedium brevicornum. The objective of this study was to investigate the protective effects of EPS on ulcerative colitis (UC) and to elucidate the underlying mechanisms involved. The findings showed that EPS treatment mitigated UC symptoms, including weight loss, anal bleeding, elevated disease activity index (DAI), and colon shortening. Hematoxylin and eosin (H&E) and Alcian blue-periodic acid-Schiff (AB-PAS) staining demonstrated that EPS alleviated histopathological damage and improved the integrity of the colonic mucosa. Mechanistically, EPS was found to substantially decrease inflammation by inhibiting the Toll-like receptor 4/nuclear factor-κB (TLR4/NF-κB) signaling pathway and to alleviate oxidative stress through modulation of the Kelch-like ECH-associated protein 1/nuclear factor erythroid-derived 2-like 2 (Keap1/Nrf2) pathway. Notably, EPS failed to exert protective effects against dextran sulfate sodium (DSS)-induced UC in Nrf2-knockout (Nrf2-/-) mice. Additionally, Western blotting and immunohistochemical analysis demonstrated that EPS facilitated autophagy via the adenosine monophosphate-dependent protein kinase/mammalian target of rapamycin (AMPK/mTOR) pathway. In vitro experiments revealed that EPS effectively suppressed lipopolysaccharide (LPS)-mediated cellular damage and oxidative stress by regulating Keap1/Nrf2 pathway. Transcriptomic analysis of LPS-treated Caco-2 cells following EPS treatment revealed a significant up-regulation of Nrf2 expression. In conclusion, the findings of this study suggest that EPS exerts protective effects against DSS-induced UC through the inhibition of the TLR4/NF-κB signaling pathway, regulation of the Keap1/Nrf2 pathway, and promotion of autophagy via the AMPK/mTOR pathway. Consequently, EPS may represent a potential therapeutic target for the treatment of UC. © 2024 Society of Chemical Industry.

CD47 and thrombospondin-1 contribute to immune evasion by Porphyromonas gingivalis

Porphyromonas gingivalis is a gram-negative anaerobic bacterium linked to periodontal disease. Remarkably, P. gingivalis thrives in an inflamed environment rich in activated neutrophils. Toll-like receptor 2 (TLR2) recognition is required for P. gingivalis to evade innate immune killing; however, the mechanisms through which P. gingivalis uncouples host inflammation from bactericidal activity are only partially known. Since integrin activation and alternative signaling are implicated in P. gingivalis TLR2-mediated immune escape, we explored the role of CD47, a widely expressed integrin-associated protein known to suppress phagocytosis and implicated as an interacting partner with other innate immune receptors. We found that CD47 associates with TLR2, and blocking CD47 leads to decreased intracellular P. gingivalis survival in macrophages in a manner dependent on the bacterial major fimbria. In vivo, CD47 knock-out mice cleared P. gingivalis more efficiently than wild-type mice. Next, we found increased expression and secretion of the CD47 ligand thrombospondin-1 (TSP-1) following P. gingivalis infection. Secreted TSP-1 broadly protected P. gingivalis and other periodontitis-associated bacterial species from neutrophil bactericidal activity. Therefore, CD47-TLR2 cosignaling in response to P. gingivalis induces TSP-1 that in turn suppresses neutrophil activity, an effect that can explain how species such as P. gingivalis survive in an inflamed environment and cause dysbiosis.

Novel Inhibitory Actions of Neuroactive Steroid [3α,5α]-3-Hydroxypregnan-20-One on Toll-like Receptor 4-Dependent Neuroimmune Signaling

The endogenous neurosteroid (3α,5α)-3-hydroxypregnan-20-one (3α,5α-THP) modulates inflammatory and neuroinflammatory signaling through toll-like receptors (TLRs) in human and mouse macrophages, human blood cells and alcohol-preferring (P) rat brains. Although it is recognized that 3α,5α-THP inhibits TLR4 activation by blocking interactions with MD2 and MyD88, the comprehensive molecular mechanisms remain to be elucidated. This study explores additional TLR4 activation sites, including TIRAP binding to MyD88, which is pivotal for MyD88 myddosome formation, as well as LPS interactions with the TLR4:MD2 complex. Both male and female P rats (n = 8/group) received intraperitoneal administration of 3α,5α-THP (15 mg/kg; 30 min) or a vehicle control, and their hippocampi were analyzed using immunoprecipitation and immunoblotting techniques. 3α,5α-THP significantly reduces the levels of inflammatory mediators IL-1β and HMGB1, confirming its anti-inflammatory actions. We found that MyD88 binds to TLR4, IRAK4, IRAK1, and TIRAP. Notably, 3α,5α-THP significantly reduces MyD88-TIRAP binding (Males: −31 ± 9%, t-test, p &lt; 0.005; Females: −53 ± 15%, t-test, p &lt; 0.005), without altering MyD88 interactions with IRAK4 or IRAK1, or the baseline expression of these proteins. Additionally, molecular docking and molecular dynamic analysis revealed 3α,5α-THP binding sites on the TLR4:MD2 complex, targeting a hydrophobic pocket of MD2 usually occupied by Lipid A of LPS. Surface plasmon resonance (SPR) assays validated that 3α,5α-THP disrupts MD2 binding of Lipid A (Kd = 4.36 ± 5.7 μM) with an inhibition constant (Ki) of 4.5 ± 1.65 nM. These findings indicate that 3α,5α-THP inhibition of inflammatory mediator production involves blocking critical protein-lipid and protein-protein interactions at key sites of TLR4 activation, shedding light on its mechanisms of action and underscoring its therapeutic potential against TLR4-driven inflammation.

Pattern Recognition Receptors in Periodontal Disease: Molecular Mechanisms, Signaling Pathways, and Therapeutic Implications

Periodontal disease remains a significant global health concern, characterized by complex host–pathogen interactions leading to tissue destruction. This review explored the role of pattern recognition receptors (PRRs) in the pathogenesis of periodontal disease, synthesizing current knowledge on their molecular mechanisms and potential as therapeutic targets. We examined the diverse family of PRRs, focusing on toll-like receptors (TLRs) and NOD-like receptors (NLRs), elucidating their activation by periodontal pathogens and subsequent downstream signaling cascades. This review highlights the intricate interplay between PRR-mediated pathways, including NF-κB and MAPK signaling, and their impact on inflammatory responses and bone metabolism in periodontal tissues. We discussed the emerging concept of PRR crosstalk and its implications for periodontal homeostasis and disease progression. Furthermore, this review addressed the potential of PRR-targeted therapies, exploring both challenges and opportunities in translating molecular insights into clinical applications. By providing an overview of PRRs in periodontal health and disease, this review aims to stimulate future research directions and inform the development of novel diagnostic and therapeutic strategies in periodontology.

Porcine decellularized nerve matrix hydrogel attenuates neuroinflammation after peripheral nerve injury by inhibiting the TLR4/MyD88/NF-κB axis

Peripheral nerve injury causes severe neuroinflammation and has become a global medical challenge. Previous research has demonstrated that porcine decellularized nerve matrix hydrogel exhibits excellent biological properties and tissue specificity, highlighting its potential as a biomedical material for the repair of severe peripheral nerve injury; however, its role in modulating neuroinflammation post–peripheral nerve injury remains unknown. Here, we aimed to characterize the anti-inflammatory properties of porcine decellularized nerve matrix hydrogel and their underlying molecular mechanisms. Using peripheral nerve injury model rats treated with porcine decellularized nerve matrix hydrogel, we evaluated structural and functional recovery, macrophage phenotype alteration, specific cytokine expression, and changes in related signaling molecules in vivo. Similar parameters were evaluated in vitro using monocyte/macrophage cell lines stimulated with lipopolysaccharide and cultured on porcine decellularized nerve matrix hydrogel–coated plates in complete medium. These comprehensive analyses revealed that porcine decellularized nerve matrix hydrogel attenuated the activation of excessive inflammation at the early stage of peripheral nerve injury and increased the proportion of the M2 subtype in monocytes/macrophages. Additionally, porcine decellularized nerve matrix hydrogel negatively regulated the Toll-like receptor 4/myeloid differentiation factor 88/nuclear factor-κB axis both in vivo and in vitro. Our findings suggest that the efficacious anti-inflammatory properties of porcine decellularized nerve matrix hydrogel induce M2 macrophage polarization via suppression of the Toll-like receptor 4/myeloid differentiation factor 88/nuclear factor-?B pathway, providing new insights into the therapeutic mechanism of porcine decellularized nerve matrix hydrogel in peripheral nerve injury.

Label-free biosensor assay decodes the dynamics of Toll-like receptor signaling.

The discovery of Toll-like receptors (TLRs) represented a significant breakthrough that paved the way for the study of host-pathogen interactions in innate immunity. However, there are still major gaps in understanding TLR function, especially regarding the early dynamics of downstream TLR pathways. Here, we present a label-free optical biosensor-based assay as a method for detecting TLR activation in a native and label-free environment and defining the dynamics of TLR pathway activation. This technology is sufficiently sensitive to detect TLR signaling and readily discriminates between different TLR signaling pathways. We define pharmacological modulators of cell surface and endosomal TLRs and downstream signaling molecules and uncover TLR signaling signatures, including potential biased receptor signaling. These findings highlight that optical biosensor assays complement traditional assays that use a single endpoint and have the potential to facilitate the future design of selective drugs targeting TLRs and their downstream effector cascades.