BRD4 Inhibition Protects Against Acute Pancreatitis Through Restoring Impaired Autophagic Flux

Unlocking the secrets of aging: Epigenetic reader BRD4 as the target to combatting aging-related diseases

BACKGROUND

Aging, a complex and profound journey, leads us through a labyrinth of physiological and pathological transformations, rendering us increasingly susceptible to aging-related diseases. Emerging investigations have unveiled the function of bromodomain containing protein 4 (BRD4) in manipulating the aging process and driving the emergence and progression of aging-related diseases.

AIM OF REVIEW

This review aims to offer a comprehensive outline of BRD4's functions involved in the aging process, and potential mechanisms through which BRD4 governs the initiation and progression of various aging-related diseases.

KEY SCIENTIFIC CONCEPTS OF REVIEW

BRD4 has a fundamental role in regulating the cell cycle, apoptosis, cellular senescence, the senescence-associated secretory phenotype (SASP), senolysis, autophagy, and mitochondrial function, which are involved in the aging process. Several studies have indicated that BRD4 governs the initiation and progression of various aging-related diseases, including Alzheimer's disease, ischemic cerebrovascular diseases, hypertension, atherosclerosis, heart failure, aging-related pulmonary fibrosis, and intervertebral disc degeneration (IVDD). Thus, the evidence from this review supports that BRD4 could be a promising target for managing various aging-related diseases, while further investigation is warranted to gain a thorough understanding of BRD4's role in these diseases.

NLRP3 inflammasome involves in the pathophysiology of sepsis-induced myocardial dysfunction by multiple mechanisms

Sepsis-induced myocardial dysfunction (SIMD) is one of the serious health-affecting problems worldwide. At present, the mechanisms of SIMD are still not clearly elucidated. The NOD-like receptor protein 3 (NLRP3) inflammasome has been assumed to be involved in the pathophysiology of SIMD by regulating multiple biological processes. NLRP3 inflammasome and its related signaling pathways might affect the regulation of inflammation, autophagy, apoptosis, and pyroptosis in SIMD. A few molecular specific inhibitors of NLRP3 inflammasome (e.g., Melatonin, Ulinastatin, Irisin, Nifuroxazide, and Ginsenoside Rg1, etc.) have been developed, which showed a promising anti-inflammatory effect in a cellular or animal model of SIMD. These experimental findings indicated that NLRP3 inflammasome could be a promising therapeutic target for SIMD treatment. However, the clinical translation of NLRP3 inhibitors for treating SIMD still requires robust in vivo and preclinical trials.

Proteomics of Plasma and Plasma-Treated Podocytes: Application to Focal and Segmental Glomerulosclerosis

Focal and segmental glomerulosclerosis (FSGS) is a severe form of idiopathic nephrotic syndrome (INS), a glomerulopathy of presumably immune origin that is attributed to extrarenal pathogenic circulating factors. The recurrence of FSGS (rFSGS) after transplant occurs in 30% to 50% of cases. The direct analysis of patient plasma proteome has scarcely been addressed to date, mainly due to the methodological difficulties associated with plasma complexity and dynamic range. In this study, first, we compared different methods of plasma preparation, second, we compared the plasma proteomes of rFSGS and controls using two preparation methods, and third, we analyzed the early proximal signaling events in podocytes subjected to patient plasma, through a combination of phosphoproteomics and lipid-raft proteomics (raftomics). By combining immunodepletion and high pH fractionation, we performed a differential proteomic analysis of soluble plasma proteins and of extracellular vesicles (EV) obtained from healthy controls, non-INS patient controls, and rFSGS patients (n = 4). In both the soluble- and the EV-protein sets from the rFSGS patients, we found a statistically significant increase in a cluster of proteins involved in neutrophil degranulation. A group of lipid-binding proteins, generally associated with lipoproteins, was found to be decreased in the soluble set from the rFSGS patients. In addition, three amino acid transporters involved in mTORC1 activation were found to be significantly increased in the EV from the rFSGS. Next, we incubated human podocytes for 30 min with 10% plasma from both groups of patients. The phosphoproteomics and raftomics of the podocytes revealed profound differences in the proteins involved in the mTOR pathway, in autophagy, and in cytoskeleton organization. We analyzed the correlation between the abundance of plasma and plasma-regulated podocyte proteins. The observed changes highlight some of the mechanisms involved in FSGS recurrence and could be used as specific early markers of circulating-factor activity in podocytes.

Integration of scRNA-Seq and Bulk RNA-Seq Reveals Molecular Characterization of the Immune Microenvironment in Acute Pancreatitis

Acute pancreatitis (AP) is an acute inflammatory disease of the exocrine pancreas. The pathogenesis of AP is still unclear, and there is currently no specific treatment. A variety of immune cells infiltrate in AP, which may play an important role in the progression of the disease. In this study, for the first time, scRNA-Seq and Bulk RNA-Seq data were used to show the characteristics of immune cell infiltration in AP, and to explore the specific molecular markers of different cell types. The present study also investigated cell-to-cell communication networks using the CellChat package, and AP-specific gene signatures (Clic1, Sat1, Serpina3n, Atf3, Lcn2, Osmr, Ccl9, Hspb1, Anxa2, Krt8, Cd44, Cd9, Hsp90aa1, Tmsb10, Hmox1, Fxyd5, Plin2, Pnp) were identified through integrative analysis of multiple sequencing datasets. We also defined disease-specific associated genes in different cell types, revealing dynamic changes through cell trajectory and pseudo-time analysis using the Monocle2 package. The results showed that macrophages were significantly increased in acute pancreatitis, and the number of interactions and interaction weight/strength of the macrophages in AP were significantly higher than those in the controls. The activities of various signaling pathways were abnormally regulated such as apoptosis, oxidative stress, lysosome, autophagy, ferroptosis, and inflammatory responses signaling pathways. In conclusion, this study comprehensively depicted the immune microenvironment of AP, explored the interaction network between different cell types, and defined AP-specific gene signatures, providing many new directions for basic research in AP.

BRD4 inhibition by JQ1 protects against LPS-induced cardiac dysfunction by inhibiting activation of NLRP3 inflammasomes

BACKGROUND

JQ1, a BRD4 inhibitor, first identified its therapeutic role in cancer, has gradually demonstrated a protective effect on the heart in recent years; however, it is unclear whether JQ1 also plays a role in LPS-induced cardiac dysfunction.

METHODS AND RESULTS

A total of forty eight mice were randomly divided into control, LPS(7.5 mg/kg), and LPS + JQ1 (50 mg/kg). JQ1 was preprotected for 1 h, and LPS was stimulated for 12 h, mouse survival and cardiac function were observed, and histopathological, serum myocardial injury markers, and inflammatory indicators, and oxidative stress levels in heart tissue were examined. The experiment found that the cardiac BRD4 levels were upregulated and the heart severe damage in the LPS group compared with the control group. While compared with the LPS group, JQ1 preprotected increased survival rate and cardiac function, reducated cardiomypathological injury and CD45 infiltration, and reduced the release of LDH, CK-MB, IL-1, IL-18, reduced MDA generation, and increased SOD viability. In addition, JQ1 preprotected also upregulated SIRT1, and inhibited the expression of NLRP3, caspase-1p20, and GSDMD. Meanwhile, similar results were obtained in LPS-treated H9C2 cells, and further intervention with the SIRT1 inhibitor EX527 partially blocked the JQ1-mediated down regulation of NLRP3, caspase-1p20, and GSDMD.

CONCLUSIONS

We propose that JQ1 may improve LPS-induced cardiac dysfunction by inhibiting SIRT1-dependent activation of NLRP3 inflammasomes, which may be a promising strategy for treating sepsis cardiomyopathy.

Possible role of transcription factors (BSX, NKX2.1, IRX3 and SIRT1) in the regulation of appetite in goldfish (Carassius auratus)

The homeobox genes play important roles in the embryonic development of animals. Recent evidence suggests they might also regulate feeding and act as transcription factors of appetite regulators. Examples of these genes are a brain-specific homeobox transcription factor (BSX), NK2 homeobox 1 (NKX2.1) and the Iroquois homeobox 3 (IRX3). Sirtuin1 (SIRT1) acts as a transcription factor for nutrient (e.g. lipid, glucose) homeostasis and responds to stress and nutrient availability, and has been shown to interact with appetite regulators. Very little is known about the role of these genes in the regulation of feeding and nutrient homeostasis in fish. In this study, we assessed the roles of BSX, NKX2.1, IRX3 and SIRT1 in the central regulation of feeding in goldfish by examining their mRNA brain distribution, assessing the effects of fasting on their brain expression and assessing the effects of peripheral injections of cholecystokinin (CCK, a brain-gut peptide), on their brain expression. All genes showed a widespread distribution in the brain, with high levels in the hypothalamus. In both hypothalamus and telencephalon, fasting induced increases in BSX, IRX3 and NKX2.1 expressions but had no effect on SIRT1 expression levels. CCK injections increased hypothalamic expression levels of IRX3 and SIRT1, and telencephalic expression levels of NKX2.1 and SIRT1, with no effect on either hypothalamic BSX or NKX2.1 expression levels or telencephalon BSX or IRX3 expression levels. Our results suggest that, in goldfish as in mammals, central BSX, NKX2.1, IRX3 and SIRT1 are present in regions of the brain regulating feeding, are sensitive to nutrient status and interact with appetite-regulating peptides.

New insights into the etiology, risk factors, and pathogenesis of pancreatitis in dogs: Potential impacts on clinical practice

While most cases of pancreatitis in dogs are thought to be idiopathic, potential risk factors are identified. In this article we provide a state‐of‐the‐art overview of suspected risk factors for pancreatitis in dogs, allowing for improved awareness and detection of potential dog‐specific risk factors, which might guide the development of disease prevention strategies. Additionally, we review important advances in our understanding of the pathophysiology of pancreatitis and potential areas for therapeutic manipulation based thereof. The outcome of pathophysiologic mechanisms and the development of clinical disease is dependent on the balance between stressors and protective mechanisms, which can be evaluated using the critical threshold theory.

Incomplete autophagy: Trouble is a friend

Incomplete autophagy is an impaired self-eating process of intracellular macromolecules and organelles in which accumulated autophagosomes do not fuse with lysosomes for degradation, resulting in the blockage of autophagic flux. In this review, we summarized the literature over the past decade describing incomplete autophagy, and found that different from the double-edged sword effect of general autophagy on promoting cell survival or death, incomplete autophagy plays a crucial role in disrupting cellular homeostasis, and promotes only cell death. What matters is that incomplete autophagy is closely relevant to the pathogenesis and progression of various human diseases, which, meanwhile, intimately linking to the pharmacologic and toxicologic effects of several compounds. Here, we comprehensively reviewed the latest progress of incomplete autophagy on molecular mechanisms and signaling pathways. Moreover, implications of incomplete autophagy for pharmacotherapy are also discussed, which has great relevance for our understanding of the distinctive role of incomplete autophagy in cellular physiology and disease. Consequently, targeting incomplete autophagy may contribute to the development of novel generation therapeutic agents for diverse human diseases.

Epigenetic regulator BRD4 is involved in cadmium-induced acute kidney injury via contributing to lysosomal dysfunction, autophagy blockade and oxidative stress

Cadmium (Cd) is a known nephrotoxic heavy metal and proximal tubules are the major target of Cd-induced acute kidney injury (AKI). We previously demonstrated that lysosomal dysfunction and dysregulated autophagy contribute to Cd-induced AKI. Recent studies have revealed that bromodomain-containing protein 4 (BRD4) is a transcriptional repressor of autophagy and lysosomal function. Hence, in vivo and in vitro studies were performed to clarify the role of BRD4 in Cd-induced AKI. Firstly, Cd has no effect on BRD4 expression levels, but increases H4K16 acetylation. Resultantly, Cd promotes the recruitment of BRD4 to lysosomal gene promoter regions to make it as a transcriptional regulator. Pharmacological and genetic inhibition of BRD4 alleviates Cd-inhibited lysosomal gene transcript levels and lysosomal function, leading to the alleviation of Cd-induced autophagy inhibition. Moreover, inhibition of BRD4 relieves Cd-induced oxidative stress and concurrent cytotoxicity, which is counteracted by the inhibition of autophagy via Atg5 knockdown, indicating that alleviation of oxidative stress by BRD4 inhibition is ascribed to its restoration of autophagic flux. Collectively, these results demonstrate that BRD4 acts as a transcriptional repressor to mediate lysosomal dysfunction, autophagy blockade and oxidative stress during Cd exposure, which may be a potential therapeutic target for Cd-induced AKI.

Effects of Snake-Derived Phospholipase A2 Inhibitors on Acute Pancreatitis: In vitro and in vivo Characterization

Objective

We aimed to investigate the effects of snake-derived phospholipase A2 inhibitor (PLA2) from Sinonatrix percarinata and Bungarus multicinctus on acute pancreatitis in vivo and in vitro and assess the mechanisms.

Methods

The levels of platelet-activating factor (PAF) and tumor necrosis factor (TNF)-α were detected by ELISA, and the characteristics of autophagy were detected by transmission electron microscopy and Western blotting (LC3, p62, and ATG5).

Results

In vitro experiments showed that PLA2 treatment caused obvious formation of autophagic bodies. By contrast, Sinonatrix and Bungarus peptides reduced the number of autophagic bodies. The concentrations of PAF and TNF-α, and the expressions of p62, autophagy-related 5 (ATG5), and microtubule-associated protein 1A/1B-light chain 3 (LC3)II/LC3I in the PLA2-treated group were significantly higher than in the control group (P<0.05). The concentrations of PAF and TNF-α, and the expressions of p62, ATG5, and LC3II/LC3I in the Sinonatrix or Bungarus peptide treatment groups were significantly lower than in the PLA2-treated cells (P<0.05). In the pancreatic tissue, autophagic bodies were observed in the model group; autophagic bodies were remarkably reduced in Sinonatrix or Bungarus peptide-treated groups compared with the model group. In vivo experiments also showed that the levels of PAF and TNF-α, and the expressions of p62, ATG5, and LC3II/LC3I were significantly higher in the model group than in the control group (P<0.05). The levels of PAF and TNF-α in the model group, and the expressions of p62, ATG5, and LC3II/LC3I in Sinonatrix or Bungarus peptide-treated groups were significantly lower than in the model group (P<0.05).

Conclusion

Sinonatrix or Bungarus peptide could ameliorate the features of acute pancreatitis, likely through regulating autophagy.