Therapeutic induction of Bcl2-associated athanogene 3-mediated autophagy in idiopathic pulmonary fibrosis

Precision cut lung slices: an integrated ex vivo model for studying lung physiology, pharmacology, disease pathogenesis and drug discovery

Precision Cut Lung Slices (PCLS) have emerged as a sophisticated and physiologically relevant ex vivo model for studying the intricacies of lung diseases, including fibrosis, injury, repair, and host defense mechanisms. This innovative methodology presents a unique opportunity to bridge the gap between traditional in vitro cell cultures and in vivo animal models, offering researchers a more accurate representation of the intricate microenvironment of the lung. PCLS require the precise sectioning of lung tissue to maintain its structural and functional integrity. These thin slices serve as invaluable tools for various research endeavors, particularly in the realm of airway diseases. By providing a controlled microenvironment, precision-cut lung slices empower researchers to dissect and comprehend the multifaceted interactions and responses within lung tissue, thereby advancing our understanding of pulmonary pathophysiology.

Pre-clinical proof-of-concept of anti-fibrotic activity of caveolin-1 scaffolding domain peptide LTI-03 in ex vivo precision cut lung slices from patients with Idiopathic Pulmonary Fibrosis

Rationale: While rodent lung fibrosis models are routinely used to evaluate novel antifibrotics, these models have largely failed to predict clinical efficacy of novel drug candidates for Idiopathic Pulmonary Fibrosis (IPF). Moreover, single target therapeutic strategies for IPF have failed and current multi-target standard of care drugs are not curative. Caveolin-1 (CAV-1) is an integral membrane protein, which, via its caveolin scaffolding domain (CSD), interacts with caveolin binding domains (CBD). CAV-1 regulates homeostasis, and its expression is decreased in IPF lungs. LTI-03 is a seven amino acid peptide derived from the CSD and formulated for dry powder inhalation; it was well tolerated in normal volunteers ( NCT04233814 ) and a safety trial is underway in IPF patients ( NCT05954988 ). Objectives: Anti-fibrotic efficacy of LTI-03 and other CSD peptides has been observed in IPF lung monocultures, and rodent pulmonary, dermal, and heart fibrosis models. This study aimed to characterize progressive fibrotic activity in IPF PCLS explants and to evaluate the antifibrotic effects of LTI-03 and nintedanib in this model. Methods: First, CBD regions were identified in IPF signaling proteins using in silico analysis. Then, IPF PCLS (n=8) were characterized by COL1A1 immunostaining, multiplex immunoassays, and bulk RNA sequencing following treatment every 12hrs with LTI-03 at 0.5, 3.0, or 10 μM; nintedanib at 0.1 μM or 1 μM; or control peptide (CP) at 10 μM. Measurements and Main Results: CBDs were present in proteins implicated in IPF, including VEGFR, FGFR and PDGFR. Increased expression of profibrotic mediators indicated active fibrotic activity in IPF PCLS over five days. LTI-03 dose dependently decreased COL1A1 staining, and like nintedanib, decreased profibrotic proteins and transcripts. Unlike nintedanib, LTI-03 did not induce cellular necrosis signals. Conclusion: IPF PCLS explants demonstrate molecular activity indicative of fibrosis during 5 days in culture and LTI-03 broadly attenuated pro-fibrotic proteins and pathways, further supporting the potential therapeutic effectiveness of LTI-03 for IPF.

Different Levels of Autophagy Activity in Mesenchymal Stem Cells Are Involved in the Progression of Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is an age-related lung interstitial disease that occurs predominantly in people over 65 years of age and for which there is a lack of effective therapeutic agents. It has demonstrated that mesenchymal stem cells (MSCs) including alveolar epithelial cells (AECs) can perform repair functions. However, MSCs lose their repair functions due to their distinctive aging characteristics, eventually leading to the progression of IPF. Recent breakthroughs have revealed that the degree of autophagic activity influences the renewal and aging of MSCs and determines the prognosis of IPF. Autophagy is a lysosome-dependent pathway that mediates the degradation and recycling of intracellular material and is an efficient way to renew the nonnuclear (cytoplasmic) part of eukaryotic cells, which is essential for maintaining cellular homeostasis and is a potential target for regulating MSCs function. Therefore, this review focuses on the changes in autophagic activity of MSCs, clarifies the relationship between autophagy and health status of MSCs and the effect of autophagic activity on MSCs senescence and IPF, providing a theoretical basis for promoting the clinical application of MSCs.

BAG3: An enticing therapeutic target for idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a dreadful and fatal disease of unknown etiology, for which no cure exists. Autophagy, a lysosomal cellular surveillance pathway is insufficiently activated in both alveolar epithelial type II cells and fibroblasts of IPF patient lungs. Fine-tuning this pathway may result in the degradation of the accumulated cargo and influence cell fate. Based on our previous data, we here present our view on modulating autophagy via a unique co-chaperone, namely Bcl2-associated athanogene3 (BAG3) in IPF and discuss about how repurposing drugs that modulate this pathway may emerge as a promising novel therapeutic approach for IPF.

Construction and experimental validation of a macrophage cell senescence-related gene signature to evaluate the prognosis, immunotherapeutic sensitivity, and chemotherapy response in bladder cancer

Tumor-associated macrophages (TAMs) are pivotal components of tumor microenvironment (TME), and senescent TAMs contribute to the alternation of the profiles of TME. However, the potential biological mechanisms and the prognosis value of senescent macrophages are largely unknown, especially in bladder cancer (BLCA). Based on the single-cell RNA sequencing of a primary BLCA sample, 23 macrophage-related genes were identified. Genomic difference analysis, LASSO, and Cox regression were used to develop the risk model. TCGA-BLCA cohort (n = 406) was utilized as the training cohort, and then, three independent cohorts (n = 90, n = 221, n = 165) from Gene Expression Omnibus, clinical samples from the local hospital (n = 27), and in vitro cell experiments were used for external validation. Aldo-keto reductase family 1 member B (AKR1B1), inhibitor of DNA binding 1 (ID1), and transforming growth factor beta 1 (TGFB1I1) were determined and included in the predictive model. The model serves as a promising tool to evaluate the prognosis in BLCA (pooled hazard ratio = 2.51, 95% confidence interval = [1.43; 4.39]). The model was also effective for the prediction of immunotherapeutic sensitivity and chemotherapy treatment outcomes, which were further confirmed by IMvigor210 cohort (P < 0.01) and GDSC dataset, respectively. Twenty-seven BLCA samples from the local hospital proved that the risk model was associated with the malignant degree (P < 0.05). At last, the human macrophage THP-1 and U937 cells were treated with H2O2 to mimic the senescent process in macrophage, and the expressions of these molecules in the model were detected (all P < 0.05).Overall, a macrophage cell senescence-related gene signature was constructed to predict the prognosis, immunotherapeutic response, and chemotherapy sensitivity in BLCA, which provides novel insights to uncover the underlying mechanisms of macrophage senescence.

BAG3 promotes autophagy and suppresses NLRP3 inflammasome activation in Parkinson's disease

Background

Neuroinflammation mediated by microglia plays a key role in the pathogenesis of Parkinson's disease (PD), and our previous studies showed this was significantly inhibited by enhanced autophagy. In the autophagy pathway, Bcl2-associated athanogene (BAG)3 is a prominent co-chaperone, and we have shown BAG3 can regulate autophagy to clear the PD pathogenic protein α-synuclein. However, the connection between BAG3 and microglia mediated neuroinflammation is not clear.

Methods

In this study, we explored whether BAG3 regulated related neuroinflammation and its original mechanism in PD. An inflammatory model of PD was established by injecting adeno-associated virus (AAV)-BAG3 into the bilateral striatum of C57BL/6 male mice to induce overexpression of BAG3, followed by injection of lipopolysaccharide (LPS). The striatum was extracted at 3 days after injection of LPS for Western blotting and reverse transcription quantitative polymerase chain reaction (RT-qPCR), and immunohistochemical staining was performed at 21 days after injection. At the same time, LPS was used to induce activation of BV2 cells to verify the effect of BAG3 in vitro.

Results

Overexpression of BAG3 reduced LPS-induced pyroptosis by reducing activation of caspase-1, the NOD-like receptor family, and the pyrin domain-containing 3 (NLRP3) inflammasome, and by release of interleukin (IL)-1β and tumor necrosis factor (TNF)-α. The LPS-induced inflammatory environment inhibits autophagy, and overexpression of BAG3 can restore autophagy, which may be the mechanism by which BAG3 reduces neuronal inflammation in PD.

Conclusions

Our results demonstrate BAG3 promotes autophagy and suppresses NLRP3 inflammasome formation in PD.