Role of Mesenchymal Stem Cells and Extracellular Vesicles in Idiopathic Pulmonary Fibrosis

Mesenchymal Stem Cell-Derived Exosomes Attenuate Murine Cytomegalovirus-Infected Pneumonia via NF-κB/NLRP3 Signaling Pathway

Reactivation and infection with cytomegalovirus (CMV) are frequently observed in recipients of solid organ transplants, bone marrow transplants, and individuals with HIV infection. This presents an increasing risk of allograft rejection, opportunistic infection, graft failure, and patient mortality. Among immunocompromised hosts, interstitial pneumonia is the most critical clinical manifestation of CMV infection. Recent studies have demonstrated the potential therapeutic benefits of exosomes derived from mesenchymal stem cells (MSC-exos) in preclinical models of acute lung injury, including pneumonia, ARDS, and sepsis. However, the role of MSC-exos in the pathogenesis of infectious viral diseases, such as CMV pneumonia, remains unclear. In a mouse model of murine CMV-induced pneumonia, we observed that intravenous administration of mouse MSC (mMSC)-exos reduced lung damage, decreased the hyperinflammatory response, and shifted macrophage polarization from the M1 to the M2 phenotype. Treatment with mMSC-exos also significantly reduced the infiltration of inflammatory cells and pulmonary fibrosis. Furthermore, in vitro studies revealed that mMSC-exos reversed the hyperinflammatory phenotype of bone marrow-derived macrophages infected with murine CMV. Mechanistically, mMSC-exos treatment decreased activation of the NF-κB/NLRP3 signaling pathway both in vivo and in vitro. In summary, our findings indicate that mMSC-exo treatment is effective in severe CMV pneumonia by reducing lung inflammation and fibrosis through the NF-κB/NLRP3 signaling pathway, thus providing promising therapeutic potential for clinical CMV infection.

Advanced 3D In Vitro Lung Fibrosis Models: Contemporary Status, Clinical Uptake, and Prospective Outlooks

Fibrosis has been characterized as a global health problem and ranks as one of the primary causes of organ dysfunction. Currently, there is no cure for pulmonary fibrosis, and limited therapeutic options are available due to an inadequate understanding of the disease pathogenesis. The absence of advanced in vitro models replicating dynamic temporal changes observed in the tissue with the progression of the disease is a significant impediment in the development of novel antifibrotic treatments, which has motivated research on tissue-mimetic three-dimensional (3D) models. In this review, we summarize emerging trends in preparing advanced lung models to recapitulate biochemical and biomechanical processes associated with lung fibrogenesis. We begin by describing the importance of in vivo studies and highlighting the often poor correlation between preclinical research and clinical outcomes and the limitations of conventional cell culture in accurately simulating the 3D tissue microenvironment. Rapid advancement in biomaterials, biofabrication, biomicrofluidics, and related bioengineering techniques are enabling the preparation of in vitro models to reproduce the epithelium structure and operate as reliable drug screening strategies for precise prediction. Improving and understanding these model systems is necessary to find the cross-talks between growing cells and the stage at which myofibroblasts differentiate. These advanced models allow us to utilize the knowledge and identify, characterize, and hand pick medicines beneficial to the human community. The challenges of the current approaches, along with the opportunities for further research with potential for translation in this field, are presented toward developing novel treatments for pulmonary fibrosis.

Alleviation of pulmonary fibrosis by the dual PPAR agonist saroglitazar and breast milk mesenchymal stem cells via modulating TGFß/SMAD pathway

Pulmonary fibrosis (PF) is a complex disorder with high morbidity and mortality. Limited efficacies of the available drugs drive researchers to seek for new therapies. Saroglitazar (Saro), a full (PPAR α/γ) agonist, is devoid of known PPAR-mediated adverse effects. Breast milk mesenchymal stem cells (BrMSCs) are contemplated to be the ideal cell type harboring differentiation/anti-inflammatory/immunosuppressive properties. Accordingly, our aims were to investigate the potential roles of Saro and/or BrMSCs in PF and to spot their underlying protective mechanisms. In this study, PF was induced by bleomycin (BLM) via intratracheal instillation. Treatment started 14 days later. Animals were treated with oral saroglitazar (3 mg/kg daily) or intraperitoneal single BrMSCs injection (0.5 ml phosphate buffer saline (PBS) containing 2 × 107 cells) or their combination with same previous doses. At the work end, 24 h following the 6 weeks of treatment period, the levels of oxidative (MDA, SOD), inflammatory (IL-1ß, IL-10), and profibrotic markers (TGF-ß, αSMA) were assessed. The autophagy-related genes (LC3, Beclin) and the expression of PPAR-α/γ and SMAD-3/7 were evaluated. Furthermore, immunohistochemical and histological work were evaluated. Our study revealed marked lung injury influenced by BLM with severe oxidative/inflammatory/fibrotic damage, autophagy inhibition, and deteriorated lung histology. Saro and BrMSCs repaired the lung structure worsened by BLM. Treatments greatly declined the oxidative/inflammatory markers. The pro-fibrotic TGF-ß, αSMA, and SMAD-3 were decreased. Contrarily, autophagy markers were increased. SMAD-7 and PPAR α/γ were activated denoting their pivotal antifibrotic roles. Co-administration of Saro and BrMSCs revealed the top results. Our findings support the study hypothesis that Saro and BrMSCs can be proposed as potential treatments for IPF.

The role of matrix metalloproteinase 9 in fibrosis diseases and its molecular mechanisms

Fibrosis is a process of tissue repair that results in the slow creation of scar tissue to replace healthy tissue and can affect any tissue or organ. Its primary feature is the massive deposition of extracellular matrix (mainly collagen), eventually leading to tissue dysfunction and organ failure. The progression of fibrotic diseases has put a significant strain on global health and the economy, and as a result, there is an urgent need to find some new therapies. Previous studies have identified that inflammation, oxidative stress, some cytokines, and remodeling play a crucial role in fibrotic diseases and are essential avenues for treating fibrotic diseases. Among them, matrix metalloproteinases (MMPs) are considered the main targets for the treatment of fibrotic diseases since they are the primary driver involved in ECM degradation, and tissue inhibitors of metalloproteinases (TIMPs) are natural endogenous inhibitors of MMPs. Through previous studies, we found that MMP-9 is an essential target for treating fibrotic diseases. However, it is worth noting that MMP-9 plays a bidirectional regulatory role in different fibrotic diseases or different stages of the same fibrotic disease. Previously identified MMP-9 inhibitors, such as pirfenidone and nintedanib, suffer from some rather pronounced side effects, and therefore, there is an urgent need to investigate new drugs. In this review, we explore the mechanism of action and signaling pathways of MMP-9 in different tissues and organs, hoping to provide some ideas for developing safer and more effective biologics.

Adipose-derived mesenchymal stem cell therapy for reverse bleomycin-induced experimental pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive respiratory disease. Arguably, the complex interplay between immune cell subsets, coupled with an incomplete understanding of disease pathophysiology, has hindered the development of successful therapies. Despite efforts to understand its pathophysiology and develop effective treatments, IPF remains a fatal disease, necessitating the exploration of new treatment options. Mesenchymal stromal/stem cell (MSC) therapy has shown promise in experimental models of IPF, but further investigation is needed to understand its therapeutic effect. This study aimed to assess the therapeutic effect of adipose-derived mesenchymal stem cells in a bleomycin-induced pulmonary fibrosis model. First, MSC cells were obtained from mice and characterized using flow cytometry and cell differentiation culture methods. Then adult C57BL/6 mice were exposed to endotracheal instillation of bleomycin and concurrently treated with MSCs for reversal models on day 14. Experimental groups were evaluated on days 14, 21, or 28. Additionally, lung fibroblasts challenged with TGF-β1 were treated with MSCs supernatant or MSCs to explore the mechanisms underlying of pulmonary fibrosis reversal. Mesenchymal stem cells were successfully isolated from mouse adipose tissue and characterized based on their differentiation ability and cell phenotype. The presence of MSCs or their supernatant stimulated the proliferation and migration of lung fibrotic cells. MSCs supernatant reduced lung collagen deposition, improved the Ashcroft score and reduced the gene and protein expression of lung fibrosis-related substances. Bleomycin-challenged mice exhibited severe septal thickening and prominent fibrosis, which was effectively reversed by MSCs treatment. MSC supernatant could suppress the TGF-β1/Smad signaling pathway and supernatant promotes fibroblast autophagy. In summary, this study demonstrates that MSCs supernatant treatment is as effective as MSCs in revert the core features of bleomycin-induced pulmonary fibrosis. The current study has demonstrated that MSCs supernatant alleviates the BLM-induced pulmonary fibrosis in vivo. In vitro experiments further reveal that MSC supernatant could suppress the TGF-β1/Smad signaling pathway to inhibit the TGF-β1-induced fibroblast activation, and promotes fibroblast autophagy by Regulating p62 expression. These findings contribute to the growing body of evidence supporting the therapeutic application of MSCs in cell therapy medicine for IPF.

Progress in understanding and treating idiopathic pulmonary fibrosis: recent insights and emerging therapies

Idiopathic pulmonary fibrosis (IPF) is a long-lasting, continuously advancing, and irrevocable interstitial lung disorder with an obscure origin and inadequately comprehended pathological mechanisms. Despite the intricate and uncharted causes and pathways of IPF, the scholarly consensus upholds that the transformation of fibroblasts into myofibroblasts-instigated by injury to the alveolar epithelial cells-and the disproportionate accumulation of extracellular matrix (ECM) components, such as collagen, are integral to IPF's progression. The introduction of two novel anti-fibrotic medications, pirfenidone and nintedanib, have exhibited efficacy in decelerating the ongoing degradation of lung function, lessening hospitalization risk, and postponing exacerbations among IPF patients. Nonetheless, these pharmacological interventions do not present a definitive solution to IPF, positioning lung transplantation as the solitary potential curative measure in contemporary medical practice. A host of innovative therapeutic strategies are presently under rigorous scrutiny. This comprehensive review encapsulates the recent advancements in IPF research, spanning from diagnosis and etiology to pathological mechanisms, and introduces a discussion on nascent therapeutic methodologies currently in the pipeline.

Immune Mechanisms of Pulmonary Fibrosis with Bleomycin

Fibrosis and structural remodeling of the lung tissue can significantly impair lung function, often with fatal consequences. The etiology of pulmonary fibrosis (PF) is diverse and includes different triggers such as allergens, chemicals, radiation, and environmental particles. However, the cause of idiopathic PF (IPF), one of the most common forms of PF, remains unknown. Experimental models have been developed to study the mechanisms of PF, and the murine bleomycin (BLM) model has received the most attention. Epithelial injury, inflammation, epithelial-mesenchymal transition (EMT), myofibroblast activation, and repeated tissue injury are important initiators of fibrosis. In this review, we examined the common mechanisms of lung wound-healing responses after BLM-induced lung injury as well as the pathogenesis of the most common PF. A three-stage model of wound repair involving injury, inflammation, and repair is outlined. Dysregulation of one or more of these three phases has been reported in many cases of PF. We reviewed the literature investigating PF pathogenesis, and the role of cytokines, chemokines, growth factors, and matrix feeding in an animal model of BLM-induced PF.