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Smooth muscle antibodies (SMA) with anti-microfilament actin (MF-SMA) specificity are regarded as highly specific markers of type 1 autoimmune hepatitis (AIH-1) but their recognition relying on immunofluorescence of vessel, glomeruli, and tubules (SMA-VGT pattern) in rodent kidney tissue, is restricted by operator-dependent interpretation. A gold standard method for their identification is not available. We assessed and compared the diagnostic accuracy for AIH-1 of an embryonal aorta vascular smooth muscle (VSM) cell line-based assay with those of the rodent tissue-based assay for the detection of MF-SMA pattern in AIH-1 patients and controls. Sera from 138 AIH-1 patients and 295 controls (105 primary biliary cholangitis, 40 primary sclerosing cholangitis, 50 chronic viral hepatitis, 20 alcohol-related liver disease, 40 steatotic liver disease, and 40 healthy controls) were assayed for MF-SMA and SMA-VGT using VSM-based and rodent tissue-based assays, respectively. MF-SMA and SMA-VGT were found in 96 (70%) and 87 (63%) AIH-1 patients, and 2 controls (P < 0.0001). Compared with SMA-VGT, MF-SMA showed similar specificity (99%), higher sensitivity (70% vs 63%, P = ns) and likelihood ratio for a positive test (70 vs 65). Nine (7%) AIH-1 patients were MF-SMA positive despite being SMA-VGT negative. Overall agreement between SMA-VGT and MF-SMA was 87% (kappa coefficient 0.870, [0.789-0.952]). MF-SMA were associated with higher serum γ-globulin [26 (12-55) vs 20 g/l (13-34), P < 0.005] and immunoglobulin G (IgG) levels [3155 (1296-7344) vs 2050 mg/dl (1377-3357), P < 0.002]. The easily recognizable IFL MF-SMA pattern on VSM cells strongly correlated with SMA-VGT and has an equally high specificity for AIH-1. Confirmation of these results in other laboratories would support the clinical application of the VSM cell-based assay for reliable detection of AIH-specific SMA., (© The Author(s) 2024. Published by Oxford University Press on behalf of the British Society for Immunology. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Background: Atherosclerosis is driven by the infiltration of the arterial intima by diverse immune cells and smooth muscle cells (SMCs). CD8 + T cells promote lesion growth during atherosclerotic lesion development, but their role in advanced atherosclerosis is less clear. Here, we studied the role of CD8 + T cells and their effects on SMCs in established atherosclerosis., Methods: CD8 + T cells were depleted in (SMC reporter) low-density lipoprotein receptor-deficient ( Ldlr -/- ) mice with established atherosclerotic lesions. Atherosclerotic lesion formation was examined, and single-cell RNA sequencing of aortic SMCs and their progeny was performed. Additionally, coculture experiments with primary aortic SMCs and CD8 + T cells were conducted., Results: Although we could not detect differences in atherosclerotic lesion size, an increased plaque SMC content was noted in mice after CD8 + T-cell depletion. Single-cell RNA sequencing of aortic lineage-traced SMCs revealed contractile SMCs and a modulated SMC cluster, expressing macrophage- and osteoblast-related genes. CD8 + T-cell depletion was associated with an increased contractile but decreased macrophage and osteoblast-like gene signature in this modulated aortic SMC cluster. Conversely, exposure of isolated aortic SMCs to activated CD8 + T cells decreased the expression of genes indicative of a contractile SMC phenotype and induced a macrophage and osteoblast-like cell state. Notably, CD8 + T cells triggered calcium deposits in SMCs under osteogenic conditions. Mechanistically, we identified transcription factors highly expressed in modulated SMCs, including Runx1 , to be induced by CD8 + T cells in cultured SMCs in an IFNγ (interferon-γ)-dependent manner., Conclusions: We here uncovered CD8 + T cells to control the SMC phenotype in atherosclerosis. CD8 + T cells promote SMC dedifferentiation and drive SMCs to adopt features of macrophage-like and osteoblast-like, procalcifying cell phenotypes. Given the critical role of SMCs in atherosclerotic plaque stability, CD8 + T cells could thus be explored as therapeutic target cells during lesion progression., Competing Interests: None.

Cerebral aneurysm (CA) represents a significant clinical challenge, characterized by pathological dilation of cerebral arteries. Recent evidence underscores the crucial involvement of immune cells in CA pathogenesis. This study aims to explore the complex interplay between immune cells and CA formation. We analyzed single-cell RNA sequencing data from the GSE193533 dataset, focusing on unruptured CA and their controls. Comprehensive cell-type identification and pseudo-time trajectory analyses were conducted to delineate the dynamic shifts in immune cell populations. Additionally, a two-sample Mendelian randomization (MR) approach was employed to investigate the causal influence of various immunophenotypes on CA susceptibility and the reciprocal effect of CA formation on immune phenotypes. Single-cell transcriptomic analysis revealed a progressive loss of vascular smooth muscle cells (VSMCs) and an increase in monocytes/macrophages (Mo/MΦ) and other immune cells, signifying a shift from a structural to an inflammatory milieu in CA evolution. MR analysis identified some vital immunophenotypes, such as CD64 on CD14+ CD16+ monocytes (OR: 1.236, 95% CI: 1.064-1.435, P = 0.006), as potential risk factors for CA development, while others, like CD28- CD8br %CD8br (OR: 0.883, 95% CI: 0.789-0.988, P = 0.030), appeared protective. Reverse MR analysis demonstrated that CA formation could modulate specific immunophenotypic expressions, highlighting a complex bidirectional interaction between CA pathology and immune response. This study underscores the pivotal role of immune cells in this process through the integration of single-cell transcriptomics with MR analysis, offering a comprehensive perspective on CA pathogenesis, and potentially guiding future therapeutic strategies targeting specific immune pathways., (© The Author(s) 2024. Published by Oxford University Press on behalf of the British Society for Immunology. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Introduction: IL-2Rα knock out (KO) mice have been instrumental to discovering the immunoregulatory properties of IL-2Rα. While initially thought of only as a stimulatory cytokine, IL-2 and IL-2Rα KO mice revealed that this cytokine-receptor system controls immune responses through restimulation-induced cell death and by promoting the survival of T regulatory cells. Although described mostly in the context of lymphocytes, recent studies by our laboratory showed that IL-2R is expressed in smooth muscle cells. Given this finding, we sought to use IL-2Rα KO to determine the function of this receptor in vascular smooth muscle cells. Surprisingly, we found that IL-2Rα KO vascular smooth muscle cells had detectable IL-2Rα., Methods: We used multiple gene and protein-based methods to determine why IL-2Rα KO vascular smooth muscle cells exhibited IL-2Rα protein. These methods included: genomic sequencing, assessing cells and tissues for evidence of maternal microchimerism, and determining the half-life of IL-2Rα protein., Results: Our studies demonstrated the following: (1) in addition to the cell surface, IL-2Rα is localized to the nucleus; (2) the genetic deletion of IL-2Rα is intact in IL-2Rα KO mice; (3) both IL-2Rα KO and WT tissues show evidence of maternal microchimerism, the likely source of IL-2Rα (4) IL-2Rα is transmitted between cells; (5) IL-2Rα has a long half-life; and (6) nuclear IL-2Rα contributes to the regulation of cell proliferation and size., Conclusion: Our findings suggest that the phenotype of complete IL-2Rα loss is more severe than demonstrated by IL-2Rα KO mice, and that IL-2Rα plays a here-to-fore unrecognized role in regulating cell proliferation in non-lymphoid cells., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Wong, Dinh, Chen and Wrenshall.)

Introduction: Vascular smooth muscle cells (VSMCs) are highly involved in airway vascular remodeling in asthma., Objectives: This study aimed to investigate the mechanisms underlying the effects of a disintegrin and metalloproteinase-33 (ADAM33) gene on the migration capacity and inflammatory cytokine secretion of VSMCs., Methods: Human aortic smooth muscle cells (HASMCs) were transfected with lentiviral vectors carrying short hairpin RNA (shRNA) targeting ADAM33 or negative control vectors. The migration capacity of HASMCs was evaluated by a transwell assay. The levels of secreted inflammatory cytokines were measured using enzyme-linked immunosorbent assay (ELISA) kits. Reverse transcription-quantitative polymerase chain reaction and Western blot assays were performed to detect mRNA and protein expression levels., Results: Silencing of ADAM33 significantly inhibited the migration of HASMCs. The expression of tumor necrosis factor alpha (TNF- α ) in the supernatant of HASMCs was decreased, while that of interferon gamma (IFN- γ ) was increased after the transfection of shRNA targeting ADAM33. Insufficient ADAM33 expression also suppressed the expression levels of phosphatidylinositol 3-kinase (PI3K), phospho-protein kinase B (AKT), phospho-mammalian target of rapamycin (mTOR), Rho-associated protein kinases, phospho-forkhead box protein O1 (FOXO1), and cyclin D1, but it did not affect the levels of AKT, mTOR, or Rho., Conclusion: Silencing of the ADAM33 gene inhibited HASMC migration and regulated inflammatory cytokine secretion via targeting the PI3K/AKT/mTOR pathway and its downstream signaling. These data contribute to a better understanding of the regulatory mechanisms of airway vascular remodeling in asthma., Competing Interests: The authors declare that there are no conflicts of interest regarding the publication of this paper., (Copyright © 2022 Fang Yan et al.)

Hexarelin, a synthetic growth hormone-releasing peptide, is shown to be protective in cardiovascular diseases such as myocardial infraction and atherosclerosis. However, the functional role of hexarelin in abdominal aortic aneurysm (AAA) remains undefined. The present study determined the effect of hexarelin administration (200 μg/kg twice per day) in a mouse model of elastase-induced abdominal aortic aneurysm. Echocardiography and in situ pictures showed hexarelin decreased infrarenal aorta diameter. Histology staining showed elastin degradation was improved in hexarelin-treated group. Hexarelin rescued smooth muscle cell contractile phenotype with increased α-SMA and decreased MMP2. Furthermore, hexarelin inhibited inflammatory cell infiltration, NLRP3 inflammasome activation and IL-18 production. Particularly, hexarelin suppressed NF-κB signaling pathway which is a key initiator of inflammatory response. These results demonstrated that hexarelin attenuated AAA development by inhibiting SMC phenotype switch and NF-κB signaling mediated inflammatory response., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Pulmonary arterial hypertension (PAH) is a progressive disease characterized by (mal)adaptive remodeling of the pulmonary vasculature, which is associated with inflammation, fibrosis, thrombosis, and neovascularization. Vascular remodeling in PAH is associated with cellular metabolic and inflammatory reprogramming that induce profound endothelial and smooth muscle cell phenotypic changes. Multiple signaling pathways and regulatory loops act on metabolic and inflammatory mediators which influence cellular behavior and trigger pulmonary vascular remodeling in vivo. This review discusses the role of bioenergetic and inflammatory impairments in PAH development.