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Abstract Background Pulmonary fibrosis (PF) represents the pathologic end stage of several interstitial lung diseases (ILDs) associated with high morbidity and mortality rates. However, current treatments can only delay disease progression rather than provide a cure. The role of inflammation in PF progression is well-established, but new insights into immune regulation are fundamental for developing more efficient therapies. c-MET signaling has been implicated in the migratory capacity and effector functions of immune cells. Nevertheless, the role of this signaling pathway in the context of PF-associated lung diseases remains unexplored. Methods To determine the influence of c-MET in immune cells in the progression of pulmonary fibrosis, we used a conditional deletion of c-Met in immune cells. To induce pulmonary fibrosis mice were administered with bleomycin (BLM) intratracheally. Over the course of 21 days, mice were assessed for weight change, and after euthanasia at different timepoints, bronchoalveolar lavage fluid cells and lung tissue were assessed for inflammation and fibrosis. Furthermore, c-MET expression was assessed in cryobiopsy sections, bronchoalveolar lavage fluid cells samples and single cell RNA-sequencing dataset from human patients with distinct interstitial lung diseases. Results c-MET expression was induced in lung immune cells, specifically in T cells, interstitial macrophages, and neutrophils, during the inflammatory phase of BLM-induced PF mouse model. Deletion of c-Met in immune cells correlated with earlier weight recovery and improved survival of BLM-treated mice. Moreover, the deletion of c-Met in immune cells was associated with early recruitment of the immune cell populations, normally found to express c-MET, leading to a subsequent attenuation of the cytotoxic and proinflammatory environment. Consequently, the less extensive inflammatory response, possibly coupled with tissue repair, culminated in less exacerbated fibrotic lesions. Furthermore, c-MET expression was up-regulated in lung T cells from patients with fibrosing ILD, suggesting a potential involvement of c-MET in the development of fibrosing disease. Conclusions These results highlight the critical contribution of c-MET signaling in immune cells to their enhanced uncontrolled recruitment and activation toward a proinflammatory and profibrotic phenotype, leading to the exacerbation of lung injury and consequent development of fibrosis.

Altered glycolytic metabolism has been associated with chemoresistance in acute myeloid leukemia (AML). However, there are still aspects that need clarification, as well as how to explore these metabolic alterations in therapy. In the present study, we aimed to elucidate the role of glucose metabolism in the acquired resistance of AML cells to cytarabine (Ara-C) and to explore it as a therapeutic target. Resistance was induced by stepwise exposure of AML cells to increasing concentrations of Ara-C. Ara-C-resistant cells were characterized for their growth capacity, genetic alterations, metabolic profile, and sensitivity to different metabolic inhibitors. Ara-C-resistant AML cell lines, KG-1 Ara-R, and MOLM13 Ara-R presented different metabolic profiles. KG-1 Ara-R cells exhibited a more pronounced glycolytic phenotype than parental cells, with a weaker acute response to 3-bromopyruvate (3-BP) but higher sensitivity after 48 h. KG-1 Ara-R cells also display increased respiration rates and are more sensitive to phenformin than parental cells. On the other hand, MOLM13 Ara-R cells display a glucose metabolism profile similar to parental cells, as well as sensitivity to glycolytic inhibitors. These results indicate that acquired resistance to Ara-C in AML may involve metabolic adaptations, which can be explored therapeutically in the AML patient setting who developed resistance to therapy.

Acute respiratory distress syndrome (ARDS) is a life-threatening lung injury that currently lacks effective clinical treatments. Evidence highlights the potential role of glycogen synthase kinase-3 (GSK-3) inhibition in mitigating severe inflammation. The inhibition of GSK-3α/β by CHIR99021 promoted fetal lung progenitor proliferation and maturation of alveolar epithelial cells (AECs). The precise impact of CHIR99021 in lung repair and regeneration during acute lung injury (ALI) remains unexplored. This study intends to elucidate the influence of CHIR99021 on AEC behaviour during the peak of the inflammatory phase of ALI and, after its attenuation, during the repair and regeneration stage. Furthermore, a long-term evaluation was conducted post CHIR99021 treatment at a late phase of the disease. Our results disclosed the role of GSK-3α/β inhibition in promoting AECI and AECII proliferation. Later administration of CHIR99021 during ALI progression contributed to the transdifferentiation of AECII into AECI and an AECI/AECII increase, suggesting its contribution to the renewal of the alveolar epithelial population and lung regeneration. This effect was confirmed to be maintained histologically in the long term. These findings underscore the potential of targeted therapies that modulate GSK-3α/β inhibition, offering innovative approaches for managing acute lung diseases, mostly in later stages where no treatment is available.

Chronic pulmonary aspergillosis (CPA) is a devastating disease with increasing prevalence worldwide. The characteristic granulomatous-like inflammation poses as the major setback to effective antifungal therapies by limiting drug access to fungi. These inflammatory lung structures are reported to be severely hypoxic; nevertheless, the underlying mechanisms whereby these processes contribute to fungal persistence remain largely unknown. Hypoxia-inducible factor 1 alpha (HIF-1α), besides being the major cellular response regulator to hypoxia, is a known central immune modulator. Here, we used a model of Aspergillus fumigatus airway infection in myeloid-restricted HIF-1α knock-out (mHif1α-/-) mice to replicate the complex structures resembling fungal granulomas and evaluate the contribution of HIF-1α to antifungal immunity and disease development. We found that fungal-elicited granulomas in mHif1α-/- mice had significantly smaller areas, along with extensive hyphal growth and increased lung fungal burden. This phenotype was associated with defective neutrophil recruitment and an increased neutrophil death, therefore highlighting a central role for HIF-1α-mediated regulation of neutrophil function in the pathogenesis of chronic fungal infection. These results hold the promise of an improved capacity to manage the progression of chronic fungal disease and open new avenues for additional therapeutic targets and niches of intervention.

Macrophages undergo a Warburg-like switch from oxidative phosphorylation to glycolysis in response to inflammatory stimulus. Here the authors show that fungal melanin can trigger this switch in human macrophages by sequestering calcium in the phagosome and enabling protection against Aspergillus fumigatus infection.

A progressive fibrosing phenotype is critical in several lung diseases. It is irreversible and associated with early patient mortality. Growing evidence has revealed pulmonary macrophages’ role as modulators of the fibrotic processes. The proportion, phenotype, and function of alveolar (AM) and interstitial macrophages (IM) at the early stages of bleomycin-induced pulmonary fibrosis have not been clearly described. In this way, our study aimed to characterize these macrophage populations and investigate the effect on fibroblast activation. C57BL/6 mice were intratracheally injected with bleomycin and were sacrificed at day 3, 5, and 7 for the performance of flow cytometry and fluorescent-activated cell sorting analysis for protein and gene expression quantification. After bleomycin administration, the proportion of IM was significantly higher than that of AM, which showed a decay during the inflammatory phase, and peaked at day 7. At day 7 of the inflammatory phase, AM started shifting their phenotype from M1-like towards M2, while IM showed a M2-like phenotype. Conditioned medium derived from IM sorted at day 7 induced fibroblast activation and differentiation in myofibroblasts in vitro. Our findings indicate that IM are the largest macrophage population at the early stages of experimental pulmonary fibrosis and are secreted mediators able to activate fibroblasts, pointing to macrophage modulation as a potential therapeutic strategy to restrain progressive fibrosing lung disorders.

Melanoma is the most aggressive and life-threatening skin cancer type. The melanoma genome is the most frequently mutated, with the BRAF mutation present in 40–60% of melanoma cases. BRAF-mutated melanomas are characterized by a higher aggressiveness and progression. Adjuvant targeted treatments, such as BRAF and MEK inhibitors, are added to surgical excision in BRAF-mutated metastatic melanomas to maximize treatment effectiveness. However, resistance remains the major therapeutic problem. Interest in natural products, like propolis, for therapeutic applications, has increased in the last years. Propolis healing proprieties offer great potential for the development of novel cancer drugs. As the activity of Portuguese propolis has never been studied in melanoma, we evaluated the antitumoral activity of propolis from Gerês (G18.EE) and its fractions (n-hexane, ethyl acetate (EtOAc), and n-butanol) in A375 and WM9 melanoma cell lines. Results from DPPH•/ABTS• radical scavenging assays indicated that the samples had relevant antioxidant activity, however, this was not confirmed in the cell models. G18.EE and its fractions decreased cell viability (SRB assay) and promoted ROS production (DHE/Mitotracker probes by flow cytometry), leading to activation of apoptotic signaling (expression of apoptosis markers). Our results suggest that the n-BuOH fraction has the potential to be explored in the pharmacological therapy of melanoma.