The leading cause of death for patients with Duchenne muscular dystrophy (DMD), a progressive muscle disease, is heart failure. Prostaglandin (PG) D₂, a physiologically active fatty acid, is synthesized from the precursor PGH₂ by hematopoietic prostaglandin D synthase (HPGDS). Using a DMD animal model (mdx mice), we previously found that HPGDS expression is increased not only in injured muscle but also in the heart. Moreover, HPGDS inhibitors can slow the progression of muscle injury and cardiomyopathy. However, the location of HPGDS in the heart is still unknown. Thus, this study investigated HPGDS expression in autopsy myocardial samples from DMD patients. We confirmed the presence of fibrosis, a characteristic phenotype of DMD, in the autopsy myocardial sections. Additionally, HPGDS was expressed in mast cells, pericytes, and myeloid cells of the myocardial specimens but not in the myocardium. Compared with the non-DMD group, the DMD group showed increased HPGDS expression in mast cells and pericytes. Our findings confirm the possibility of using HPGDS inhibitor therapy to suppress PGD₂ production to treat skeletal muscle disorders and cardiomyopathy. It thus provides significant insights for developing therapeutic drugs for DMD.

Hericenone C is one of the most abundant secondary metabolites derived from Hericium erinaceus, under investigation for medicinal properties. Here, we report that Hericenone C inhibits the second phase of formalin-induced nociceptive behavior in mice. As the second phase is involved in inflammation, in a mechanistic analysis on cultured cells targeting NF-κB response element (NRE): luciferase (Luc)-expressing cells, lipopolysaccharide (LPS)-induced NRE::Luc luciferase activity was found to be significantly inhibited by Hericenone C. Phosphorylation of p65, which is involved in the inflammatory responses of the NF-κB signaling pathway, was also induced by LPS and significantly reduced by Hericenone C. Additionally, in mice, the number of CD11c-positive cells increased in the paw during the peak of the second phase of the formalin test, which decreased upon Hericenone C intake. Our findings confirm the possibility of Hericenone C as a novel therapeutic target for pain-associated inflammation.

Defects in Aryl hydrocarbon receptor nuclear translocator-like 1 (ARNTL), a central component of the circadian clock mechanism, may promote or inhibit the induction of inflammation by monocytes/macrophages, with varying effects on different diseases. However, ARNTL’s role in monocytes/macrophages under chronic kidney disease (CKD), which presents with systemic inflammation, is unclear. Here, we report that the expression of Arntl in monocytes promoted CKD-induced cardiac damage. The expression of G-protein-coupled receptor 68 (GPR68), which exacerbates CKD-induced cardiac disease, was regulated by ARNTL. Under CKD conditions, GPR68 expression was elevated via ARNTL, particularly in the presence of PU.1, a transcription factor specific to monocytes and macrophages. In CKD mouse models lacking monocyte-specific ARNTL, GPR68 expression in monocytes was reduced, leading to decreased cardiac damage and fibrosis despite no improvement in renal excretory capacity or renal fibrosis and increased angiotensin II production. The loss of ARNTL did not affect the expression of marker molecules, indicating the origin or differentiation of cardiac macrophages, but affected GPR68 expression only in cardiac macrophages derived from mature monocytes, highlighting the significance of the interplay between GPR68 and ARNTL in monocytes/macrophages and its influence on cardiac pathology. Understanding this complex relationship between circadian clock mechanisms and disease could help uncover novel therapeutic strategies.

Antigen-presenting cells (APCs) play a crucial role in the immune system by breaking down antigens into peptide fragments that subsequently bind to major histocompatibility complex (MHC) molecules. Previous studies indicate that stable proteins can impede CD4⁺ T cell stimulation by hindering antigen processing and presentation. Conversely, certain proteins require stabilization in order to activate the immune response. Several factors, including the characteristics of the protein and the utilization of different adjuvants in animal experiments, may contribute to this disparity. In this study, we investigated the impact of adjuvants on antigen administration in mice, specifically focusing on the stability of the CH₂ domain. Consequently, the CH₂ domain induced a stronger IgG response in comparison to the stabilized one when using Alum and PBS (without adjuvant). On the other hand, animal experiment using Freund’s adjuvant showed the opposite results. These findings indicate the significance of considering the intrinsic conformational stability of a protein when eliciting its immunogenicity, particularly within the context of vaccine development.