The Pyrazole Derivative BTP2 Attenuates IgG Immune Complex-induced Inflammation

The Effects of Insulin-Like Growth Factor I and BTP-2 on Acute Lung Injury

Acute lung injury (ALI) afflicts approximately 200,000 patients annually and has a 40% mortality rate. The COVID-19 pandemic has massively increased the rate of ALI incidence. The pathogenesis of ALI involves tissue damage from invading microbes and, in severe cases, the overexpression of inflammatory cytokines such as tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β). This study aimed to develop a therapy to normalize the excess production of inflammatory cytokines and promote tissue repair in the lipopolysaccharide (LPS)-induced ALI. Based on our previous studies, we tested the insulin-like growth factor I (IGF-I) and BTP-2 therapies. IGF-I was selected, because we and others have shown that elevated inflammatory cytokines suppress the expression of growth hormone receptors in the liver, leading to a decrease in the circulating IGF-I. IGF-I is a growth factor that increases vascular protection, enhances tissue repair, and decreases pro-inflammatory cytokines. It is also required to produce anti-inflammatory 1,25-dihydroxyvitamin D. BTP-2, an inhibitor of cytosolic calcium, was used to suppress the LPS-induced increase in cytosolic calcium, which otherwise leads to an increase in proinflammatory cytokines. We showed that LPS increased the expression of the primary inflammatory mediators such as toll like receptor-4 (TLR-4), IL-1β, interleukin-17 (IL-17), TNF-α, and interferon-γ (IFN-γ), which were normalized by the IGF-I + BTP-2 dual therapy in the lungs, along with improved vascular gene expression markers. The histologic lung injury score was markedly elevated by LPS and reduced to normal by the combination therapy. In conclusion, the LPS-induced increases in inflammatory cytokines, vascular injuries, and lung injuries were all improved by IGF-I + BTP-2 combination therapy.

Effect of BTP2 on agonist-induced vasoconstriction in the mouse aorta in vitro

BTP2 is a potent inhibitor of store-operated Ca2+ entry (SOCE), which plays a vital role in vasoconstriction. However, the direct effect of BTP2 on the contractile response remains unclear. Here, we investigated the effects and mechanisms of action of BTP2 in the mouse aorta. Isometric tension was measured using a Multi Myograph System with two stainless steel wires. Ca2+ transient was recorded by confocal laser scanning microscope. The results showed that BTP2 markedly suppressed vasoconstriction mediated by SOCE and Ca2+ influx mediated by SOCE. The cumulative concentration of BTP2 had no effect on the baseline of mouse aortic rings, whereas it increased vasoconstriction stimulated by 3 μmol/L Phenylephrine. BTP2 (1 μmol/L) significantly increased vasoconstriction induced by 3 μmol/L Phe or cumulative concentration. BTP2 also promoted noradrenaline-induced aortic contraction. However, Phe- and noradrenaline-induced contraction was not affected by 0.3 or 3 μmol/L BTP2, and BTP2 at 10 μmol/L significantly suppressed aortic contraction. BTP2 inhibited 5-HT-evoked contraction in a concentration-dependent manner. BTP2 at higher concentrations (>3 μmol/L) inhibited CaCl2 -induced and 60 mmol/L K+ -induced contraction with progressive reduction of maximal contraction in a concentration-dependent manner. These results suggest that 1 μmol/L BTP2 increases contraction evoked by α1 adrenoreceptor activation. BTP2 at higher concentrations may inhibit Cav1.2 channels.

ORAI1 Ca2+ Channel as a Therapeutic Target in Pathological Vascular Remodelling

In the adult, vascular smooth muscle cells (VSMC) are normally physiologically quiescent, arranged circumferentially in one or more layers within blood vessel walls. Remodelling of native VSMC to a proliferative state for vascular development, adaptation or repair is driven by platelet-derived growth factor (PDGF). A key effector downstream of PDGF receptors is store-operated calcium entry (SOCE) mediated through the plasma membrane calcium ion channel, ORAI1, which is activated by the endoplasmic reticulum (ER) calcium store sensor, stromal interaction molecule-1 (STIM1). This SOCE was shown to play fundamental roles in the pathological remodelling of VSMC. Exciting transgenic lineage-tracing studies have revealed that the contribution of the phenotypically-modulated VSMC in atherosclerotic plaque formation is more significant than previously appreciated, and growing evidence supports the relevance of ORAI1 signalling in this pathologic remodelling. ORAI1 has also emerged as an attractive potential therapeutic target as it is accessible to extracellular compound inhibition. This is further supported by the progression of several ORAI1 inhibitors into clinical trials. Here we discuss the current knowledge of ORAI1-mediated signalling in pathologic vascular remodelling, particularly in the settings of atherosclerotic cardiovascular diseases (CVDs) and neointimal hyperplasia, and the recent developments in our understanding of the mechanisms by which ORAI1 coordinates VSMC phenotypic remodelling, through the activation of key transcription factor, nuclear factor of activated T-cell (NFAT). In addition, we discuss advances in therapeutic strategies aimed at the ORAI1 target.

Cross-reactive antibodies against dust mite-derived enolase induce neutrophilic airway inflammation

BACKGROUND AND AIMS

Neutrophilic inflammation is a hallmark of some specific asthma phenotypes; its aetiology is not yet fully understood. House dust mite (HDM) is the most common factor in the pathogenesis of airway inflammation. This study aims to elucidate the role of cross-antibodies against HDM-derived factors in the development of neutrophilic inflammation in the airway.

METHODS

Blood samples were collected from asthma patients with chronic neutrophilic asthma for analysis of HDM-specific cross-reactive antibodies. The role of an antibody against HDM-derived enolase (EnoAb) in the impairment of airway epithelial barrier function and induction of airway inflammation was assessed in a cell culture model and an animal model.

RESULTS

High similarity (72%) of the enolase gene sequences was identified between HDM and human. Serum EnoAb was detected in patients with chronic neutrophilic asthma. The EnoAb bound to airway epithelial cells to form complexes with enolase, which activated complement, impaired airway epithelial barrier functions and induced neutrophilic inflammation in the airway tissues.

CONCLUSIONS

HDM-derived enolase can induce specific cross-antibodies in humans, which induce neutrophilic inflammation in the airway.

The Blockade of Store-Operated Calcium Channels Improves Decompression Sickness in Rats

Background

Previous investigations reveal that BTP2, a store-operated calcium channel blocker, has protective and anti-inflammatory properties in multiple inflammatory diseases. This study investigates whether BTP2 can protect against decompression sickness (DCS) in a rat model.

Methods

BTP2 (2 mg/kg) was administered to male Sprague–Dawley rats 30 min before subjecting them to hyperbaric pressure. Control rats were not treated. After decompression, signs of DCS were examined, and samples of bronchoalveolar lavage fluid and lung tissue were obtained for evaluation.

Results

The incidence and mortality of DCS were decreased significantly in rats treated with BTP2 compared to those treated with dimethyl sulfoxide. BTP2 significantly attenuated DCS-induced lung edema, histological evidence of lung inflammation, necroptosis, and apoptosis, while it decreased levels of tumor necrosis factor alpha, interleukin-6, and cytokine-induced neutrophil chemoattractant-1 in bronchoalveolar lavage fluid. In addition, BTP2 reduced the expression of nuclear factor of activated T cells and early growth response protein 3 in lung tissue. BTP2 also significantly increased the levels of inhibitor kappa B alpha and suppressed the levels of nuclear factor kappa B in lung tissue.

Conclusion

The results suggest that BTP2 may has potential as a prophylactic therapy to attenuate DCS-induced injury.

CRAC channel regulation of innate immune cells in health and disease

Calcium is a major intracellular signaling messenger in innate immune cells. Similar to other immune cell subsets, the majority of calcium entry into innate immune cells is induced by cell surface receptors that stimulate store-operated calcium entry through calcium-release activated calcium (CRAC) channels. Since the molecular description of the STIM family of calcium sensors and the ORAI family of CRAC channel proteins, the majority of studies support a dominant role for these proteins in calcium signaling in innate cells. In reviewing the literature on CRAC channel function in innate cells, several general themes emerge. All innate cells express multiple members of the STIM and ORAI family members, however the ratio and relative contribution of individual isoforms changes depending on the cell type and activation state of the cell. It is evident that study of functional roles for STIM molecules is clearly ahead of studies of specific ORAI family members in all innate cell types, and that studies of CRAC channels in innate cells are not nearly as advanced as studies in lymphocytes. However, taken together, evidence from both STIM calcium sensors and ORAI channels in innate cells indicates that deficiency of STIM and ORAI proteins tends not to affect the development of any innate cell lineage, but certainly affects their function, in particular activation of the neutrophil oxidase and mast cell activation via IgE receptors. Furthermore, there are clearly hints that therapeutic targeting of CRAC channels in innate cells offers a new approach to various inflammatory and allergic diseases.

Store-operated calcium entry in thrombosis and thrombo-inflammation

Cytosolic free calcium (Ca²⁺) is a second messenger regulating a wide variety of functions in blood cells, including adhesion, activation, proliferation and migration. Store-operated Ca²⁺ entry (SOCE), triggered by depletion of Ca²⁺ from the endoplasmic reticulum, provides a main mechanism of regulated Ca²⁺ influx in blood cells. SOCE is mediated and regulated by isoforms of the ion channel proteins ORAI and TRP, and the transmembrane Ca²⁺ sensors stromal interaction molecules (STIMs), respectively. This report provides an overview of the (patho)physiological importance of SOCE in blood cells implicated in thrombosis and thrombo-inflammation, i.e. platelets and immune cells. We also discuss the physiological consequences of dysregulated SOCE in platelets and immune cells and the potential of SOCE inhibition as a therapeutic option to prevent or treat arterial thrombosis as well as thrombo-inflammatory disease states such as ischemic stroke.

Ion Channels in Pulmonary Hypertension: A Therapeutic Interest?

Pulmonary arterial hypertension (PAH) is a multifactorial and severe disease without curative therapies. PAH pathobiology involves altered pulmonary arterial tone, endothelial dysfunction, distal pulmonary vessel remodeling, and inflammation, which could all depend on ion channel activities (K⁺, Ca²⁺, Na⁺ and Cl^-). This review focuses on ion channels in the pulmonary vasculature and discusses their pathophysiological contribution to PAH as well as their therapeutic potential in PAH.