Cleavage-Mediated Regulation of Myd88 Signaling by Inflammasome-Activated Caspase-1

Effects of metal oxide nanoparticles on healthy and psoriasis-like human epidermal keratinocytes in vitro

The use of metal oxide nanoparticles (NPs) in skincare products has significantly increased human skin exposure, raising safety concerns. Whilst NP's ability to penetrate healthy skin is minimal, studies have demonstrated that metal oxide NPs can induce toxicity in keratinocytes through direct contact. Moreover, NP's effect on common skin disorders like psoriasis, where barrier impairments and underlying inflammation could potentially increase NP penetration and worsen nanotoxicity is largely unstudied. In this paper, we investigated whether psoriasis-like human keratinocytes (Pso HKs) would exhibit heightened toxic responses to titanium dioxide (TiO2), zinc oxide (ZnO), and/or silica (SiO2) NPs compared to healthy HKs. Cells were exposed to each NP at concentrations ranging between 0.5 and 500 µg/ml for 6, 24, and 48 h. Amongst the metal oxide NPs, ZnO NPs produced the most pronounced toxic effects in both cell types, affecting cell viability, inducing oxidative stress, and activating the inflammasome pathway. Notably, only in ZnO NPs-treated Pso HKs, trappin-2/pre-elafin was cleaved intracellularly through a non-canonical process. In addition, tissue remodelling-related cytokines were upregulated in ZnO NP-treated Pso HKs. The full impact of the observed outcomes on psoriatic symptoms will need further evaluation. Nonetheless, our findings indicate the importance of understanding the sub-lethal impacts of NP exposures on keratinocytes, even though direct exposure may be low, particularly in the context of skin disorders where repeated and long-term exposures are anticipated.

Schnitzler Syndrome: Insights into Its Pathogenesis, Clinical Manifestations, and Current Management

Schnitzler syndrome is a rare disorder characterized by a chronic urticarial rash associated with immunoglobulin M (IgM) monoclonal gammopathy. Schnitzler syndrome shares strong clinicopathologic similarities with monogenic IL-1-mediated autoinflammatory disorders and is now considered an acquired adult-onset autoinflammatory disease. The spectacular effect of interleukin-1 inhibitors demonstrates the key role of this cytokine in the pathogenesis of the disease. However, the physiopathology of Schnitzler syndrome remains elusive, and the main question regarding the relationship between autoinflammatory features and monoclonal gammopathy is still unanswered. The purpose of this narrative review is to describe what is currently known about the pathogenesis of this peculiar disease, as well as to address its diagnosis and management.

Cordyceps militaris Solid Medium Extract Alleviates Lipoteichoic Acid-Induced MH-S Inflammation by Inhibiting TLR2/NF-κB/NLRP3 Pathways

The aim of this study was to investigate the inhibitory effects of Cordyceps militaris solid medium extract (CME) and cordycepin (COR) on LTA-induced inflammation in MH-S cells and their mechanisms of action. In this study, the establishment of an LTA-induced MH-S inflammation model was determined, the CCK-8 method was used to determine the safe concentration range for a drug for COR and CME, the optimal concentration of COR and CME to exert anti-inflammatory effects was further selected, and the expression of inflammatory factors of TNF-α, IL-1β, IL-18, and IL-6 was detected using ELISA. The relative expression of TNF-α, IL-1β, IL-18, IL-6, IL-10, TLR2 and MyD88 mRNA was detected using RT-PCR, and the IL-1β, IL-18, TLR2, MyD88, NF-κB p-p65, NLRP3, pro-caspase-1, Caspase-1 and ASC protein expression in the cells were detected using Western blot; immunofluorescence assay detected the expression of Caspase-1 in MH-S cells. The results revealed that both CME and COR inhibited the levels of IL-1β, IL-18, IL-6, and TNF-α in the supernatants of LTA-induced MH-S cells and the mRNA expression levels of IL-1β, IL-18, IL-6, TNF-α, TLR2 and MyD88, down-regulated the LTA-induced IL-1β, IL-18, TLR2 in MH-S cells, MyD88, NF-κB p-p65/p65, NLRP3, ASC, pro-caspase-1, and caspase-1 protein expression levels, and inhibited LTA-induced caspase-1 activation in MH-S cells. In conclusion, CME can play a therapeutic role in LTA-induced inflammation in MH-S cells via TLR2/NF-κB/NLRP3, and may serve as a potential drug for bacterial pneumonia caused by Gram-positive bacteria.

Potentilla paradoxa Nutt. Ethanol Extract Exhibits Anti-Inflammatory Effects by Suppression of the Src/NF-κB Signaling Pathway

Inflammation is an immune response that protects against harmful stimuli. However, severe inflammation can cause many diseases, such as diabetes, cancer, and arthritis. In this study, we examined the anti-inflammatory efficacy and mechanism of Potentilla paradoxa Nutt. ethanol extract (Pp-EE) as a new strategy for controlling the inflammatory response. Cellular activities and the molecular target of Pp-EE were identified in RAW264.7 cells and HEK293T cells. The effect of Pp-EE was analyzed using the Griess assay, the luciferase assay, reverse transcription-polymerase chain reaction, and Western blotting. To evaluate the in vivo effects, an HCl/EtOH-induced gastritis mouse model was used. NO production and pro-inflammatory gene (iNOS, COX-2, and TNF-α) mRNA levels were decreased by Pp-EE in a concentration-dependent manner without showing cytotoxicity. The activation of the transcription factor, particularly NF-κB, was effectively suppressed by Pp-EE. It was also found that Pp-EE directly inhibits the activation of Src in lipopolysaccharide (LPS)-treated RAW264.7 cells and in Src-overexpressed HEK293 cells by Western blotting analysis and cellular thermal shift assay. Experiments in the gastritis mouse model indicated that Pp-EE suppresses HCl/EtOH-induced gastric lesions, the expression levels of COX-2, IL-6, and TNF-α, and the phosphorylation of p65, p50, and Src. Taken together, these results suggest that Pp-EE can be applied as an anti-inflammatory remedy with a Src/NF-κB inhibitory property.

Focus on the Role of the NLRP3 Inflammasome in Multiple Sclerosis: Pathogenesis, Diagnosis, and Therapeutics

Neuroinflammation is initiated with an aberrant innate immune response in the central nervous system (CNS) and is involved in many neurological diseases. Inflammasomes are intracellular multiprotein complexes that can be used as platforms to induce the maturation and secretion of proinflammatory cytokines and pyroptosis, thus playing a pivotal role in neuroinflammation. Among the inflammasomes, the nucleotide-binding oligomerization domain-, leucine-rich repeat- and pyrin domain-containing 3 (NLRP3) inflammasome is well-characterized and contributes to many neurological diseases, such as multiple sclerosis (MS), Alzheimer's disease (AD), and ischemic stroke. MS is a chronic autoimmune disease of the CNS, and its hallmarks include chronic inflammation, demyelination, and neurodegeneration. Studies have demonstrated a relationship between MS and the NLRP3 inflammasome. To date, the pathogenesis of MS is not fully understood, and clinical studies on novel therapies are still underway. Here, we review the activation mechanism of the NLRP3 inflammasome, its role in MS, and therapies targeting related molecules, which may be beneficial in MS.