InVivoMAb anti-mouse IL-18

Metabolic-inflammatory crosstalk orchestrates muscle repair. Although pyroptosis typically aggravates sterile injury, we demonstrated that GSDME-dependent pyroptotic signaling associated with recruited myeloid cells paradoxically supported regeneration. GSDME expression was induced in postsurgical human muscle injury and murine damage models. Gsdme deficiency delayed functional recovery and exacerbated injury-induced myosteatosis, a pathological form of intramuscular ectopic fat deposition. Time-series and scRNA-seq analyses revealed that GSDME loss shifted the transcriptional program from oxidative metabolism to lipid storage and adipogenesis. Lipidomics confirmed aberrant accumulation of triacylglycerols (TAGs) and sphingolipids in Gsdme-deficient muscle. Single-cell profiling further identified divergent fibro-adipogenic progenitor (FAP) states skewed toward adipogenesis, accompanied by impaired expansion of restorative Lyve1+Cd163+Txnip+ tissue-resident macrophages (TRMs), as validated by multiplex flow cytometry. Blocking CCR2-dependent monocyte recruitment produced regenerative defects comparable with those caused by Gsdme deficiency. Myeloid-specific Gsdme reintroduction rescued TRM expansion and function and curbed FAP adipogenic reprogramming, whereas FAP-specific expression proved ineffective. Mechanistically, IL-18 downstream of GSDME-dependent signaling engaged KLF4/JUN signaling in TRMs, sustaining their reparative and lipid-clearing capacity. This GSDME-IL-18-TRM axis was compromised in aged muscle, yet exogenous IL-18 reversed myosteatosis and accelerated regeneration. Together, these findings suggest that GSDME-dependent pyroptotic signaling can act as a metabolic checkpoint that sustains TRM-driven lipid homeostasis to support muscle regeneration.

Clonal hematopoiesis (CH) driven by JAK2V617F is known to accelerate atherosclerosis through inflammasome activation and release of interleukin (IL)-1β and -18; yet, the specific contribution of IL-18 has remained unclear. In this study, we demonstrate that antibody inhibition of IL-18 in JAK2V617F CH mice increases plaque collagen but paradoxically promotes both early lesion growth and advanced necrotic core formation. Mechanistically, IL-18 blockade reverses absent in melanoma 2 inflammasome activation but shifts cell death toward apoptosis, and together with impaired efferocytosis, results in greater necrosis. These events are coordinated by reduced interferon gamma signaling, which enhances collagen deposition while decreasing expression of efferocytotic genes. Our findings challenge the prevailing notion that IL-18 inhibition stabilizes atherosclerotic plaques and provide new mechanistic insight into the interplay among inflammasome biology, adaptive immunity, and plaque stability.

Discovering more targets is of great importance for developing alternative interventions for tumor therapy. The roles of transmembrane protein 175 (TMEM175) in neurodegeneration diseases have been reported, however its functions in tumor immune surveillance are not known. We show that TMEM175 conditional knockout in macrophages inhibits the tumor growth and metastasis through promoting the anti-tumor immunity in the tumor microenvironment (TME), including elevated M1-like polarization, reduced M2-like polarization, and facilitated recruitment and activation of T cells and nature killer cells (NKs). The anti-tumor immunity is abrogated by caspase-1 inhibitor VX-765, anti-IL-1β, and anti-IL-18. Tmem175-/- bone marrow-derived macrophages (BMDMs) show enhanced tumor antigen cross-presentation that is further strengthened by IL-1β and IL-18. NLRP3 is robustly elicited in Tmem175-/- BMDMs by the tumor cell debris through lysosomal permeabilization and cathepsin B leakage. Finally, Tmem175-/- mice are more responsive to anti-PD-1. Our works implies TMEM175 to be a potential target for immunotherapy.

Nucleoside-modified messenger RNA (mRNA) vaccines elicit protective antibodies through their ability to promote T follicular helper (Tfh) cell differentiation. The lipid nanoparticles (LNPs) of mRNA vaccines possess inherent adjuvant activity. However, the extent to which the nucleoside-modified mRNA is sensed and contributes to Tfh cell responses remains undefined. Herein, we deconvolute the signals induced by LNPs and mRNA that instruct dendritic cells (DCs) to promote Tfh cell differentiation. We demonstrate that the mRNA drives the production of type I interferons, which act on DCs to enhance their maturation and Tfh cell differentiation, and favors plasma cells and memory B cell responses. In parallel, LNPs, which allow for mRNA uptake by DCs within the draining lymph node, also modulate Tfh cell responses by shaping the localization of CD25+ DCs. Our work unravels distinct adjuvant features of mRNA and LNPs necessary for the induction of Tfh cells, with implications for rational vaccine design.