Pharmacological blockade of the MaxiK channel attenuates experimental acute pancreatitis and associated lung injury in rats

The Effect of MaxiK Channel on Regulating the Activation of NLRP3 Inflammasome in Rats of Blast-induced Traumatic Brain Injury

Abundant findings including our previous work proved that the NOD-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome exerts a key role in the process of neuroinflammation following blast-induced traumatic brain injury (bTBI). The opening of potassium channels leads to low K⁺ environment in cells, which appears to be an essential requirement for NLRP3 inflammasome activation. Notably, MaxiK (BK) channel is significant for K⁺ transport. The present study is aim to investigate the potential role of MaxiK in the activation of NLRP3 and to evaluate whether MaxiK channel blocker paxilline could confer beneficial effects on attenuating the severity of bTBI in rats. Rats were randomly assigned into five groups (n = 8). MaxiK channel expression was measured in bTBI rats. The effect of paxilline on the expression of NLRP3 inflammasome, the level of inflammatory cytokines, brain injury biomarkers in serum and brain edema were also evaluated in bTBI rats. The results showed that the expression of MaxiK was elevated significantly in the cerebral cortex of bTBI rats. The treatment of MaxiK channel blocker paxilline suppressed the NLRP3 inflammasome expression substantially. In addition, paxilline could also decrease the level of pro-inflammatory cytokines and the biomarkers of brain injury and alleviate brain edema of bTBI rats. Our findings have revealed that MaxiK channel might be involved in the process of neuroinflammation of bTBI. Paxilline could depress neuro-inflammation response and alleviate brain injury by blocking MaxiK channel and subsequently inhibition of NLRP3 inflammasome activation.

Protective effect of methylsulfonylmethane in caerulein-induced acute pancreatitis and associated lung injury in mice

Objectives

In the present study, we have elaborated the anti-inflammatory mechanism of MSM through homing of CD34+ stem cells towards an inflamed region by regulating hydrogen sulfide (H2S) in an in vivo model of caerulein-induced acute pancreatitis (AP) and associated lung injury.

Methods

Male Swiss mice were treated with hourly intraperitoneal injections of caerulein (50 μg/kg) for 6 h. MSM (500 mg/kg) was administered intraperitoneally 1 h after the first caerulein injection (therapeutic). The serum amylase activity and myeloperoxidase (MPO) activity in lung and pancreas were measured. The levels of H2S and interleukin (IL)-1β, cystathionine-γ-lyase (CSE) and CD34+ expressions in pancreas and lungs were determined by RT-PCR and ELISA.

Key Findings

Methylsulfonylmethane significantly ameliorated pancreas and lung histopathological changes, decreased serum amylase, MPO activity and inhibited caerulein-induced IL-1β expression. Furthermore, MSM reduced caerulein-induced H2S levels by alleviating the expression of CSE in pancreas and lungs and increased CD34 expression and inhibited nuclear factor (NF)-κB translocation in caerulein-induced AP and associated lung injury.

Conclusions

These findings indicate that MSM can effectively reduce inflammatory responses and induce the homing of CD34+ cells to the injured tissues.

Involvement of the PI3K/Akt/NF-κB Signaling Pathway in the Attenuation of Severe Acute Pancreatitis-Associated Acute Lung Injury by Sedum sarmentosum Bunge Extract

Sedum sarmentosum Bunge possesses excellent anti-inflammatory properties and was used in the treatment of inflammatory diseases. The aim of the present study was to investigate the efficiency of Sedum sarmentosum Bunge extract (SSBE) on severe acute pancreatitis-associated (SAP-associated) acute lung injury (ALI) in rats and to explore the underlying mechanisms. Here, we used a sodium taurocholate-induced SAP rat model to determine the role of SSBE in ALI. During the course of pancreatitis, the expressions of phosphorylated phosphoinositide 3-kinases (PI3K)/protein kinase B (Akt) and nuclear factor-kappa B (NF-κB) p65 in the lungs were upregulated. Meanwhile, a parallel increase in the levels of interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) in the lungs was observed after the induction of SAP. Treatment with SSBE significantly reduced the expression of p-Akt and p-p65 in the lungs and attenuated the severity of SAP-associated ALI compared to the SAP group at 12 h and 24 h. In summary, this study showed that SSBE has beneficial effects on SAP-associated ALI, probably through the PI3-K/Akt signaling pathways by suppressing the NF-κB activities.

Recent advances in therapeutic strategies that focus on the regulation of ion channel expression

A number of different ion channel types are involved in cell signaling networks, and homeostatic regulatory mechanisms contribute to the control of ion channel expression. Profiling of global gene expression using microarray technology has recently provided novel insights into the molecular mechanisms underlying the homeostatic and pathological control of ion channel expression. It has demonstrated that the dysregulation of ion channel expression is associated with the pathogenesis of neural, cardiovascular, and immune diseases as well as cancers. In addition to the transcriptional, translational, and post-translational regulation of ion channels, potentially important evidence on the mechanisms controlling ion channel expression has recently been accumulated. The regulation of alternative pre-mRNA splicing is therefore a novel therapeutic strategy for the treatment of dominant-negative splicing disorders. Epigenetic modification plays a key role in various pathological conditions through the regulation of pluripotency genes. Inhibitors of pre-mRNA splicing and histone deacetyalase/methyltransferase have potential as potent therapeutic drugs for cancers and autoimmune and inflammatory diseases. Moreover, membrane-anchoring proteins, lysosomal and proteasomal degradation-related molecules, auxiliary subunits, and pharmacological agents alter the protein folding, membrane trafficking, and post-translational modifications of ion channels, and are linked to expression-defect channelopathies. In this review, we focused on recent insights into the transcriptional, spliceosomal, epigenetic, and proteasomal regulation of ion channel expression: Ca(2+) channels (TRPC/TRPV/TRPM/TRPA/Orai), K(+) channels (voltage-gated, KV/Ca(2+)-activated, KCa/two-pore domain, K2P/inward-rectifier, Kir), and Ca(2+)-activated Cl(-) channels (TMEM16A/TMEM16B). Furthermore, this review highlights expression of these ion channels in expression-defect channelopathies.

Fatty Acid Ethyl Esters Are Less Toxic Than Their Parent Fatty Acids Generated during Acute Pancreatitis

Although ethanol causes acute pancreatitis (AP) and lipolytic fatty acid (FA) generation worsens AP, the contribution of ethanol metabolites of FAs, ie, FA ethyl esters (FAEEs), to AP outcomes is unclear. Previously, pancreata of dying alcoholics and pancreatic necrosis in severe AP, respectively, showed high FAEEs and FAs, with oleic acid (OA) and its ethyl esters being the most abundant. We thus compared the toxicities of FAEEs and their parent FAs in severe AP. Pancreatic acini and peripheral blood mononuclear cells were exposed to FAs or FAEEs in vitro. The triglyceride of OA (i.e., glyceryl tri-oleate) or OAEE was injected into the pancreatic ducts of rats, and local and systemic severities were studied. Unsaturated FAs at equimolar concentrations to FAEEs induced a larger increase in cytosolic calcium, mitochondrial depolarization, and necro-apoptotic cell death. Glyceryl tri-oleate but not OAEE resulted in 70% mortality with increased serum OA, a severe inflammatory response, worse pancreatic necrosis, and multisystem organ failure. Our data show that FAs are more likely to worsen AP than FAEEs. Our observations correlate well with the high pancreatic FAEE concentrations in alcoholics without pancreatitis and high FA concentrations in pancreatic necrosis. Thus, conversion of FAs to FAEE may ameliorate AP in alcoholics.

The role of Card9 overexpression in peripheral blood mononuclear cells from patients with aseptic acute pancreatitis

Activated mononuclear cells are an early event in the course of severe acute pancreatitis (SAP). To date, the molecular mechanism triggering peripheral blood mononuclear cells (PBMCs) is poorly understood. The aim of this paper was to determine the potential role of Card9 in SAP. We collected data from 72 subjects between January 2013 and June 2014. Subsequently, PBMCs were isolated on day 1, 3 and 5 of pancreatitis. Immunofluorescence staining, quantitative real‐time PCR, Western blotting, immunoprecipitation and ELISA were used to determine the role of Card9 in SAP. Microbial culture showed that SAP patients at the early period did not develop any bacteria and fungi infection. Card9 expression in SAP patients was higher than that in mild acute pancreatitis and volunteer healthy controls, up to the peak on day 1. The monocyte‐derived cytokines interleukin (IL)‐17, IL‐1β, IL‐6 and tumour necrosis factor‐α mediated by the induction of Card9 markedly increased in SAP patients compared with the control group. Furthermore, the inducible formation of Card9‐Bcl10 complex was found in PBMCs, which may be involved in nuclear factor kappa B (NF‐κB) and p38 activation in SAP. Receiver operating characteristic curve indicated that Card9 levels had a high sensitivity of 87.5% and specificity of 67.7%, showing the close correlation with SAP patients. Card9 overexpression was firstly found in aseptic SAP, which may be played an important role in NF‐κB and p38 activation in PBMCs. It also provided the new insights into therapeutic interventions by targeting monocytes activation in SAP patients.

Therapeutic implications of innate immune system in acute pancreatitis

INTRODUCTION

Acute pancreatitis (AP) is an inflammatory disorder of the pancreas encompassing a cascade of cellular and molecular events. It starts from premature activation of zymogens with the involvement of innate immune system to a potential systemic inflammatory response and multiple organ failure. Leukocytes are the major cell population that participate in the propagation of the disease. Current understanding of the course of AP is still far from complete, limiting treatment options mostly to conservative supportive care. Emerging evidence has pointed to modulation of the immune system for strategic therapeutic development, by mitigating the inflammatory response and severity of AP. In the current review, we have focused on the role of innate immunity in the condition and highlighted therapeutics targeting it for treatment of this challenging disease.

AREAS COVERED

The current review has aimed to elaborate in-depth understanding of specific roles of innate immune cells, derived mediators and inflammatory pathways that are involved in AP. Summarizing the recent therapeutics and approaches applied experimentally that target immune responses to attenuate AP.

EXPERT OPINION

The current state of knowledge on AP, limitations of presently available therapeutic approaches and the promise of therapeutic implications of innate immune system in AP are discussed.