Differential regulation of lipopolysaccharide-induced IL-1β and TNF-α production in macrophages by palmitate via modulating TLR4 downstream signaling

T cell dysregulation in rheumatoid arthritis: Recent advances and natural product interventions

Autoimmune diseases result from chronic and dysregulated activation of the immune system, culminating in pathological self-tissue damage. These disorders are primarily driven by adaptive immune responses, particularly those mediated by T and B lymphocytes, which mistakenly target self-antigens expressed in host tissues. In rheumatoid arthritis (RA), the pathogenesis is closely associated with the emergence of tissue-invasive effector T cells and the functional impairment of regulatory T cells (Tregs), both of which play pivotal roles in disease progression. Therapeutic interventions targeting these dysregulated T cell populations have emerged as a promising strategy for RA management. Although synthetic immunosuppressants remain the mainstay of RA treatment, their long-term application is often hampered by adverse effects, diminished therapeutic efficacy, and poor patient adherence. These limitations highlight the critical need for the development of novel therapeutic approaches. Natural compounds derived from medicinal plants have been widely utilized in the clinical management of RA, with growing evidence supporting their immunomodulatory potential, particularly in restoring T cell-mediated immune tolerance. This review aims to provide a comprehensive overview of recent advances in understanding T cell dysregulation in RA and to elucidate the mechanisms through which natural compounds regulate immune responses. By integrating current findings, this work seeks to offer a theoretical foundation for the optimized use of natural compounds in the treatment of RA, while exploring their potential in advancing precision medicine and personalized therapeutic strategies.

Chickpea-resistant starch exhibits bioactive function for alleviating atopic dermatitis via regulating butyrate production

Resistant starch (RS) is one of the bioactive polysaccharides to produce Short-chain fatty acids (SCFAs) in the colon and contributes to allergic diseases including atopic dermatitis (AD). However, the bioactive mechanism of RS relieving AD needs to be elucidated. In this study, RS was prepared using chickpeas. Its microstructure and crystal structure were thoroughly characterized. Chickpea RS significantly improved the clinical symptoms and restored Th1/Th2 immune balance in mice with AD induced by calcipotriol. These benefits were eliminated by antibiotic cocktail treatment, suggesting that gut microbiota mediated the alleviation effects of chickpea RS on AD. Based on metagenomic sequencing and untargeted metabolomic analysis, chickpea RS treatment significantly increased the proportions of Butyricimonas virosa, Bifidobacterium pseudolongum, and Faecalibaculum rodentium, and a total of 206 differential metabolites were altered, especially the increase in propionate and butyrate production. Furthermore, we found that acylated butyrate, but not propionate, improved the pathological characteristics by activating GPR109A, which inhibit the phosphorylation levels of IκB-α, p50, p65, JNK, and p-JNK. Collectively, chickpea RS exhibited the bioactive function for regulating the communication of the gut-skin axis via regulating butyrate production to activate GPR109A.

Design, Synthesis and Biological Activities Evaluation of Novel Pterostilbene-Urea Derivatives as Potential Anti-Inflammatory Agents

1. The toxicity of derivatives was removed by the reasonable modification of bioactive skeleton. 2. As potential COX-2 inhibitor with IC50 values ranging from 39.42 to 179.84 nM/L, compounds (Q4-Q10, Q20) exhibited superior anti-inflammatory activity at low micromolar concentrations. 3. Q7 (IC50 (COX-2)= 61.05 nM/L), Q10 (IC50 (COX-2)= 54.68 nM/L) and Q20 (IC50 (COX-2)= 39.42 nM/L) showed stronger COX-2 inhibitory abilities than Celecoxib (IC50 (COX-2)= 67.89 nM/L). 4. The strongest anti-inflammatory agent, Q20 (IC50 NO= 9.96 μM/L, IC50 (COX-2)= 39.42 nM/L) effectively inhibited the secretion of IL-1β and TNF-α, exhibited the IC50 values of 12.30 and 9.07 μM/L respectively. 5. Q20 exerted as anti-inflammatory actives via targeting COX-2, down-regulating iNOS and TLR4 protein, and inhibiting the activation of NLRP3 inflammasome and NF-κB signal pathway.

Lysosomes finely control macrophage inflammatory function via regulating the release of lysosomal Fe2+ through TRPML1 channel

Lysosomes are best known for their roles in inflammatory responses by engaging in autophagy to remove inflammasomes. Here, we describe an unrecognized role for the lysosome, showing that it finely controls macrophage inflammatory function by manipulating the lysosomal Fe2+-prolyl hydroxylase domain enzymes (PHDs)-NF-κB-interleukin 1 beta (IL1B) transcription pathway that directly links lysosomes with inflammatory responses. TRPML1, a lysosomal cationic channel, is activated secondarily to ROS elevation upon inflammatory stimuli, which in turn suppresses IL1B transcription, thus limiting the excessive production of IL-1β in macrophages. Mechanistically, the suppression of IL1B transcription caused by TRPML1 activation results from its modulation on the release of lysosomal Fe2+, which subsequently activates PHDs. The activated PHDs then represses transcriptional activity of NF-κB, ultimately resulting in suppressed IL1B transcription. More importantly, in vivo stimulation of TRPML1 ameliorates multiple clinical signs of Dextran sulfate sodium-induced colitis in mice, suggesting TRPML1 has potential in treating inflammatory bowel disease.

Identification and functional characterization of a novel cystatin in amphioxus, ancient origin of vertebrate type-2 cystatin homologues

Cystatins are well known as a vast superfamily of functional proteins participated in the reversible competitive inhibition of cysteine proteases. Currently, increasing evidences point to the extensive phylogenetic diversity and crucial immune roles of type-2 cystatins in the vertebrate species. However, no information is available regarding the homologue in cephalochordate amphioxus, the representative of most basal living chordates, whose immune regulation are still ambiguous. Here, we clearly identified the presence of type-2 cystatin gene in amphioxus Branchiostoma japonicum, termed Bjcystatin-2, which was structurally characterized by typical wedge-shaped cystatin feature. Evolutionary analyses revealed that Bjcystatin-2 is the putative ancestral type-2 cystatin for chordates, with gene diversity emerging through duplication events. The expression of Bjcystatin-2 showed tissue-specific profile and was inducible upon invasive pathogens. Significantly, the recombinant Bjcystatin-2 exhibited not merely cathepsin L inhibitory activity, but also the ability to bind with bacteria and their characteristic molecules. Furthermore, Bjcystatin-2 also showed the capacity to enhance the macrophage-driven bacterial phagocytosis and to attenuate the generation of pro-inflammatory cytokines within macrophages. In summary, these findings demonstrate that Bjcystatin-2 exhibits dual role acting as both a protease inhibitor and an immunoactive molecule, greatly enriching our understanding of immune defense mechanisms of type-2 cystatin within the amphioxus.

Piper longum L. ameliorates gout through the MAPK/PI3K-AKT pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Gout, a painful joint disease with a prevalence ranging from 0.86% to 2.2% in China over the past decade. Traditional medicine has long utilized the medicinal and edible Piper longum L. (PL) fruit spikes for treating gout and other joint conditions like rheumatoid arthritis. However, the exact mechanisms behind its effectiveness remain unclear.

AIM OF THE STUDY

This study aimed to investigate the potential of alcoholic extracts from PL fruit spikes as a safe and effective treatment for gout. We used a combined network pharmacology and experimental validation approach to evaluate the mechanisms behind the anti-gout properties of PL.

MATERIALS AND METHODS

UPLC-Q/TOF-MS analysis determined the major components of PL. Subsequently, network pharmacology analysis predicted potential molecular targets and related signaling pathways for the anti-gout activity of PL. Molecular docking simulations further explored the interactions between PL compounds and proteins and characterized the properties of potential bioactive secondary metabolites. Mouse models of air pouch inflammation and hyperuricemia were further established, and the anti-gout mechanism of PL was confirmed by examining the expression of proteins related to the MAPK and PI3K-AKT pathways in the tissue.

RESULTS

Our analysis revealed 220 bioactive secondary metabolites within PL extracts. Network pharmacology and molecular docking results indicated that these metabolites primarily combat gout by modulating the PI3K-AKT and MAPK signaling pathways. In vivo experiments have also proven that PL at a dose of 100 mg/kg can optimally reduce acute inflammation of gout and kidney damage caused by high uric acid. The anti-gout mechanism involves the PI3K-AKT/MAPK signaling pathway and its downstream NF-κB pathway.

CONCLUSION

This study provides compelling evidence for PL's therapeutic potential in gout management by modulating key inflammatory pathways. The findings offer a strong foundation for future clinical exploration of PL as a gout treatment option.

Inhibition of macrophage MAPK/NF-κB pathway and Th2 axis by mangiferin ameliorates MC903-induced atopic dermatitis

Available online Atopic dermatitis (AD) is a chronic, persistent inflammatory skin disease characterized by eczema-like lesions and itching. Although topical steroids have been reported for treating AD, they are associated with adverse effects. Thus, safer medications are needed for those who cannot tolerate these agents for long periods. Mangiferin (MAN) is a flavonoid widely found in many herbs, with significant anti-inflammatory and immunomodulatory activities. However, the potential modulatory effects and mechanisms of MAN in treating Th2 inflammation in AD are unknown. In the present study, we reported that MAN could reduce inflammatory cell infiltration and scratching at the lesion site by decreasing MC903-induced levels of Th2-type cytokines, Histamine, thymic stromal lymphopoietin, Leukotriene B4, and immunoglobulin E. The mechanism may be related to reductions in MAPK and NF-κB-associated protein phosphorylation by macrophages. The results suggested that MAN may be a promising therapeutic agent for AD.

Nanoparticle-Mediated Delivery of Flavonoids: Impact on Proinflammatory Cytokine Production: A Systematic Review

Flavonoids are a diverse group of plant-derived compounds that have been shown to have various health benefits, including anti-inflammatory effects. However, their use in the treatment of inflammatory diseases has been limited due to their low bioavailability. The nanoparticle-mediated delivery of flavonoids has been proposed as a potential solution to this issue, as it allows the sustained release of the flavonoids over time. There are several different nanoparticle systems that have been developed for flavonoid delivery, including polymeric nanoparticles, liposomes, and inorganic nanoparticles. This systematic review aims to evaluate the impact of nanoparticle-mediated delivery of flavonoids on pro-inflammatory cytokine production in various diseases. We analyzed the performance of flavonoid-encapsulated nanoparticles in regulating cytokine production in different in vitro and in vivo studies. To this end, we followed the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) to conduct a comprehensive search of the literature and to assess the quality of the included studies. The results showed that flavonoid-encapsulated nanoparticles significantly downregulated pro-inflammatory cytokines, such as TNF-α, IL-1β, IL-6, and IL-18. In some cases, this effect was significantly greater than that observed with non-encapsulated flavonoids These findings suggest that nanoparticle-mediated delivery of flavonoids may have potential as a therapeutic approach for the treatment of inflammatory diseases.

A new frontier for fat: dietary palmitic acid induces innate immune memory

Dietary saturated fats have recently been appreciated for their ability to modify innate immune cell function, including monocytes, macrophages, and neutrophils. Many dietary saturated fatty acids (SFAs) embark on a unique pathway through the lymphatics following digestion, and this makes them intriguing candidates for inflammatory regulation during homeostasis and disease. Specifically, palmitic acid (PA) and diets enriched in PA have recently been implicated in driving innate immune memory in mice. PA has been shown to induce long-lasting hyper-inflammatory capacity against secondary microbial stimuli in vitro and in vivo, and PA-enriched diets alter the developmental trajectory of stem cell progenitors in the bone marrow. Perhaps the most relevant finding is the ability of exogenous PA to enhance clearance of fungal and bacterial burdens in mice; however, the same PA treatment enhances endotoxemia severity and mortality. Westernized countries are becoming increasingly dependent on SFA-enriched diets, and a deeper understanding of SFA regulation of innate immune memory is imperative in this pandemic era.

Enriched dietary saturated fatty acids induce trained immunity via ceramide production that enhances severity of endotoxemia and clearance of infection

Trained immunity is an innate immune memory response that is induced by a primary inflammatory stimulus that sensitizes monocytes and macrophages to a secondary pathogenic challenge, reprogramming the host response to infection and inflammatory disease. Dietary fatty acids can act as inflammatory stimuli, but it is unknown if they can act as the primary stimuli to induce trained immunity. Here we find mice fed a diet enriched exclusively in saturated fatty acids (ketogenic diet; KD) confer a hyper-inflammatory response to systemic lipopolysaccharide (LPS) and increased mortality, independent of diet-induced microbiome and hyperglycemia. We find KD alters the composition of the hematopoietic stem cell compartment and enhances the response of bone marrow macrophages, monocytes, and splenocytes to secondary LPS challenge. Lipidomics identified enhanced free palmitic acid (PA) and PA-associated lipids in KD-fed mice serum. We found pre-treatment with physiologically relevant concentrations of PA induces a hyper-inflammatory response to LPS in macrophages, and this was dependent on the synthesis of ceramide. In vivo, we found systemic PA confers enhanced inflammation and mortality in response to systemic LPS, and this phenotype was not reversible for up to 7 days post-PA-exposure. Conversely, we find PA exposure enhanced clearance of Candida albicans in Rag1-/- mice. Lastly, we show that oleic acid, which depletes intracellular ceramide, reverses PA-induced hyper-inflammation in macrophages and enhanced mortality in response to LPS. These implicate enriched dietary SFAs, and specifically PA, in the induction of long-lived innate immune memory and highlight the plasticity of this innate immune reprogramming by dietary constituents.