Pulmonary fibrosis, a debilitating lung disorder characterised by excessive fibrous tissue accumulation in lung parenchyma, compromises respiratory function leading to a life-threatening respiratory failure. While its origins are multifaceted and poorly understood, the urokinase system, including urokinase-type plasminogen activator (uPA) and its receptor (uPAR), plays a significant role in regulating fibrotic response, extracellular matrix remodelling, and tissue repair. Mesenchymal stem/stromal cells (MSCs) hold promise in regenerative medicine for treating pulmonary fibrosis. Our study aimed to investigate the potential of MSCs to inhibit pulmonary fibrosis as well as the contribution of uPAR expression to this effect. We found that intravenous MSC administration significantly reduced lung fibrosis in the bleomycin-induced pulmonary fibrosis model in mice as revealed by MRI and histological evaluations. Notably, administering the MSCs isolated from adipose tissue of uPAR knockout mice (Plaur-/- MSCs) attenuated lung fibrosis to a lesser extent as compared to WT MSCs. Collagen deposition, a hallmark of fibrosis, was markedly reduced in lungs treated with WT MSCs versus Plaur-/- MSCs. Along with that, endogenous uPA levels were affected differently; after Plaur-/- MSCs were administered, the uPA content was specifically decreased within the blood vessels. Our findings support the potential of MSC treatment in attenuating pulmonary fibrosis. We provide evidence that the observed anti-fibrotic effect depends on uPAR expression in MSCs, suggesting that uPAR might counteract the uPA accumulation in lungs.
© 2024 International Federation of Cell Biology.

The regulation of polymorphonuclear leukocyte (PMN) function by mechanical forces encountered during their migration across restrictive endothelial cell junctions is not well understood. Using genetic, imaging, microfluidic, and in vivo approaches, we demonstrated that the mechanosensor Piezo1 in PMN plasmalemma induced spike-like Ca2+ signals during trans-endothelial migration. Mechanosensing increased the bactericidal function of PMN entering tissue. Mice in which Piezo1 in PMNs was genetically deleted were defective in clearing bacteria, and their lungs were predisposed to severe infection. Adoptive transfer of Piezo1-activated PMNs into the lungs of Pseudomonas aeruginosa-infected mice or exposing PMNs to defined mechanical forces in microfluidic systems improved bacterial clearance phenotype of PMNs. Piezo1 transduced the mechanical signals activated during transmigration to upregulate nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 4, crucial for the increased PMN bactericidal activity. Thus, Piezo1 mechanosensing of increased PMN tension, while traversing the narrow endothelial adherens junctions, is a central mechanism activating the host-defense function of transmigrating PMNs.
Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.

Locoregional monotherapy with heterodimeric interleukin (IL)-15 (hetIL-15) in a triple-negative breast cancer (TNBC) orthotopic mouse model resulted in tumor eradication in 40% of treated mice, reduction of metastasis, and induction of immunological memory against breast cancer cells. hetIL-15 re-shaped the tumor microenvironment by promoting the intratumoral accumulation of cytotoxic lymphocytes, conventional type 1 dendritic cells (cDC1s), and a dendritic cell (DC) population expressing both CD103 and CD11b markers. These CD103intCD11b+DCs share phenotypic and gene expression characteristics with both cDC1s and cDC2s, have transcriptomic profiles more similar to monocyte-derived DCs (moDCs), and correlate with tumor regression. Therefore, hetIL-15, a cytokine directly affecting lymphocytes and inducing cytotoxic cells, also has an indirect rapid and significant effect on the recruitment of myeloid cells, initiating a cascade for tumor elimination through innate and adoptive immune mechanisms. The intratumoral CD103intCD11b+DC population induced by hetIL-15 may be targeted for the development of additional cancer immunotherapy approaches.
Published by Elsevier Inc.

Cerebral hypoperfusion has been proposed as a potential cause of postictal neurological dysfunction in epilepsy, but its underlying mechanism is still unclear. We show that a 30% reduction in postictal cerebral blood flow (CBF) has two contributing factors: the early hypoperfusion up to ∼30 min post-seizure was mainly induced by arteriolar constriction, while the hypoperfusion that persisted for over an hour was due to increased capillary stalling induced by neutrophil adhesion to brain capillaries, decreased red blood cell (RBC) flow accompanied by constriction of capillaries and venules, and elevated intercellular adhesion molecule-1 (ICAM-1) expression. Administration of antibodies against the neutrophil marker Ly6G and against LFA-1, which mediates adhesive interactions with ICAM-1, prevented neutrophil adhesion and recovered the prolonged CBF reductions to control levels. Our findings provide evidence that seizure-induced neutrophil adhesion to cerebral microvessels via ICAM-1 leads to prolonged postictal hypoperfusion, which may underlie neurological dysfunction in epilepsy.
© 2023.

Emerging evidence suggests that the mechanism of chemotherapy-induced cell death may influence the antitumor immune response in patients with cancer. Unlike immunologically silent apoptosis, pyroptosis is a lytic and inflammatory form of programmed cell death characterized by pore formation in the cell membrane and release of proinflammatory factors. Gasdermin E (GSDME) has recently gained attention after cleavage of GSDME by certain chemotherapeutics has been shown to elicit pyroptosis. This study investigated the immunomodulatory effects of a mesothelin-targeting antibody drug conjugate (ADC) in mouse models of breast and colon cancer.
The antitumor effects of the ADC were studied in EMT6 breast cancer and CT26 colon cancer syngeneic mouse models. The immunomodulatory effects of the ADC were assessed by analysis of tumor-infiltrating immune cells using flow cytometry. ADC mechanism of action was evaluated by morphology, biological assays, ADC-mediated cleavage of key effector proteins, and CRISPR/Cas9-mediated knockout (KO). Finally, the antitumor effect of ADC and Fms-like tyrosine kinase-3 ligand (Flt3L) combination therapy was evaluated in tumors expressing GSDME as well as in GSDME-silenced tumors.
The data demonstrated that the ADC controlled tumor growth and stimulated anticancer immune responses. Investigation of the mechanism of action revealed that tubulysin, the cytotoxic payload of the ADC, induced cleavage of GSDME and elicited pyroptotic cell death in GSDME-expressing cells. Using GSDME KO, we showed that GSDME expression is critical for the effectiveness of the ADC as a monotherapy. Combining the ADC with Flt3L, a cytokine that expands dendritic cells in both lymphoid and non-lymphoid tissues, restored control of GSDME KO tumors.
Together, these results show for the first time that tubulysin and a tubulysin containing ADC can elicit pyroptosis, and that this fiery cell death is critical for antitumor immunity and therapeutic response.
© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.