NPS 2143, a selective calcium-sensing receptor antagonist inhibits lipopolysaccharide-induced pulmonary inflammation. Mol Immunol. 2017;90:150-157. [PMID: 28800474 DOI: 10.1016/j.molimm.2017.07.012]

Vasoconstriction-inhibiting factor: an endogenous inhibitor of vascular calcification as a calcimimetic of calcium-sensing receptor

AIMS

Patients with chronic kidney disease (CKD) show a high risk of cardiovascular diseases, predominantly caused by accelerated vascular calcification. Vascular calcification is a highly regulated process with no current treatment. The vasoconstriction-inhibiting factor (VIF) peptide was recently discovered with vasoregulatory properties, but no information regarding calcification has been described.

METHODS AND RESULTS

In the present work, the inhibitory calcification effect of the VIF peptide was analysed in vitro in vascular smooth muscle cells (VSMCs), ex vivo in rat aortic rings, as well as in vivo in rats treated with vitamin D and nicotine (VDN). The VIF peptide inhibits vascular calcification by acting as a calcimimetic for the calcium-sensing receptor, increasing carboxylated matrix Gla protein production and blocking the activation of calcification pathways. The VIF peptide decreased calcium influx, the production of reactive oxygen species, and the activation of multiple kinases in VSMCs. Furthermore, calcium deposition in the aortas of patients with CKD negatively correlates with the VIF peptide concentration. Moreover, we show the cleavage of the VIF peptide from chromogranin-A by 'proprotein convertase subtilisin/kexin type 2' and 'carboxypeptidase E' enzymes. In addition, 'cathepsin K' degrades the VIF peptide. The active site of the native 35 amino acid-sequence long VIF peptide was identified with seven amino acids, constituting a promising drug candidate with promise for clinical translation.

CONCLUSION

The elucidation of the underlying mechanism by which the VIF peptide inhibits vascular calcification, as well as the active sequence and the cleavage and degradation enzymes, forms the basis for developing preventive and therapeutic measures to counteract vascular calcification.

Targeting the Calcium-Sensing Receptor in Chemically Induced Medium-Grade Colitis in Female BALB/C Mice

BACKGROUND/OBJECTIVES

The extracellular calcium-sensing receptor (CaSR) is a multifunctional receptor proposed as a possible drug target for inflammatory bowel disease. We showed previously that CaSR inhibition with NPS 2143, a negative allosteric modulator of the CaSR, somewhat ameliorated the symptoms of chemically induced severe colitis in mice. However, it was unclear whether the potential of CaSR inhibition to reduce colitis may have been overshadowed by the severity of the induced inflammation in our previous study. Therefore, we tested if CaSR inhibition could prevent medium-grade colitis.

METHODS

Female BALB/c mice were treated with NPS 2143 or a vehicle prior to the induction of colitis with 2.5% DSS. On the day of sacrifice, colons and plasma were collected. The histology score was determined based on hematoxylin-eosin-stained sections. Mucin content, proliferation (Ki67), and immune cell infiltration (CD3 and CD20) were quantified based on immunostainings. Gene expression was measured by RT-qPCR.

RESULTS

Treatment with NPS 2143 had no effect on the clinical symptom score of the mice. However, the colons of the mice in the treated group were significantly longer (p < 0.05), and NPS 2143 significantly reduced colon ulceration (p < 0.05). The treatment also significantly reduced the expression of COX2 in the proximal colon and IL-22 in the distal colon. The proliferation of cells in the lymph nodes was significantly lower after the treatment, but no difference was observed in the epithelial cells.

CONCLUSIONS

In summary, while NPS 2143 had an anti-inflammatory effect on medium-grade colitis, this effect appeared to be milder than in severe colitis, as observed previously, indicating that the effectiveness of CaSR inhibition as an anti-inflammatory measure in the colon is proportional to disease severity.

Calcium-sensing receptor-mediated macrophage polarization improves myocardial remodeling in spontaneously hypertensive rats

Chronic inflammation is a key element in the progression of essential hypertension (EH). Calcium plays a key role in inflammation, so its receptor, the calcium-sensing receptor (CaSR), is an essential mediator of the inflammatory process. Compelling evidence suggests that CaSR mediates inflammation in tissues and immune cells, where it mediates their activity and chemotaxis. Macrophages (Mφs) play a major role in the inflammatory response process. This study provided convincing evidence that R568, a positive regulator of CaSR, was effective in lowering blood pressure in spontaneously hypertensive rats (SHRs), improving cardiac function by alleviating cardiac hypertrophy and fibrosis. R568 can increase the content of CaSR and M2 macrophages (M2Mφs, exert an anti-inflammatory effect) in myocardial tissue, reduce M1 macrophages (M1Mφs), which have a pro-inflammatory effect in this process. In contrast, NPS2143, a negative state regulator of CaSR, exerted the opposite effect in all of the above experiments. Following this study, R568 increased CaSR content in SHR myocardial tissue, lowered blood pressure, promoted macrophages to M2Mφs and improved myocardial fibrosis, but interestingly, both M1Mφs and M2Mφs were increased in the peritoneal cavity of SHRs, the number of M2Mφs remained lower than M1Mφs. In vitro, R568 increased CaSR content in RAW264.7 cells (a macrophage cell line), regulating intracellular Ca2+ ([Ca2+]i) inhibited NOD-like receptor family protein 3 (NLRP3) inflammasome activation and ultimately prevented its conversion to M1Mφs. The results showed that a decrease in CaSR in hypertensive rats causes further development of hypertension and cardiac damage. EH myocardial remodeling can be improved by CaSR overexpression by suppressing NLRP3 inflammasome activation and macrophage polarization toward M1Mφs and increasing M2Mφs.

Phenylalanine promotes alveolar macrophage pyroptosis via the activation of CaSR in ARDS

Acute respiratory distress syndrome (ARDS) is associated with high mortality rates in patients admitted to the intensive care unit (ICU) patients with overwhelming inflammation considered to be an internal cause. The authors' previous study indicated a potential correlation between phenylalanine levels and lung injury. Phenylalanine induces inflammation by enhancing the innate immune response and the release of pro-inflammatory cytokines. Alveolar macrophages (AMs) can respond to stimuli via synthesis and release of inflammatory mediators through pyroptosis, one form of programmed cell death acting through the nucleotide-binging oligomerization domain-like receptors protein 3 (NLRP3) signaling pathway, resulting in the cleavage of caspase-1 and gasdermin D (GSDMD) and the release of interleukin (IL) -1β and IL-18, aggravating lung inflammation and injury in ARDS. In this study, phenylalanine promoted pyroptosis of AMs, which exacerbated lung inflammation and ARDS lethality in mice. Furthermore, phenylalanine initiated the NLRP3 pathway by activating the calcium-sensing receptor (CaSR). These findings uncovered a critical mechanism of action of phenylalanine in the context of ARDS and may be a new treatment target for ARDS.

The CaSR/TRPV4 coupling mediates pro-inflammatory macrophage function

AIM

Although calcium-sensing receptor (CaSR) and transient receptor potential vanilloid 4 (TRPV4) channels are functionally expressed on macrophages, it is unclear if they work coordinately to mediate macrophage function. The present study investigates whether CaSR couples to TRPV4 channels and mediates macrophage polarization via Ca²⁺ signaling.

METHODS

The role of CaSR/TRPV4/Ca²⁺ signaling was assessed in lipopolysaccharide (LPS)-treated peritoneal macrophages (PMs) from wild-type (WT) and TRPV4 knockout (TRPV4 KO) mice. The expression and function of CaSR and TRPV4 in PMs were analyzed by immunofluorescence and digital Ca²⁺ imaging. The correlation factors of M1 polarization, CCR7, IL-1β, and TNFα were detected using q-PCR, western blot, and ELISA.

RESULTS

We found that PMs expressed CaSR and TRPV4, and CaSR activation-induced marked Ca²⁺ signaling predominately through extracellular Ca²⁺ entry, which was inhibited by selective pharmacological blockers of CaSR and TRPV4 channels. The CaSR activation-induced Ca²⁺ signaling was significantly attenuated in PMs from TRPV4 KO mice compared to those from WT mice. Moreover, the CaSR activation-induced Ca²⁺ entry via TRPV4 channels was inhibited by blocking phospholipases A2 (PLA2)/cytochromeP450 (CYP450) and phospholipase C (PLC)/Protein kinase C (PKC) pathways. Finally, CaSR activation promoted the expression and release of M1-associated cytokines IL-1β and TNFɑ, which were attenuated in PMs from TRPV4 KO mice.

CONCLUSION

We reveal a novel coupling of the CaSR and TRPV4 channels via PLA2/CYP450 and PLC/PKC pathways, promoting a Ca²⁺ -dependent M1 macrophage polarization. Modulation of this coupling and downstream pathways may become a potential strategy for the prevention/treatment of immune-related disease.

Fexofenadine protects against lipopolysaccharide-induced acute lung injury by targeting cytosolic phospholipase A2

OBJECTIVE

Acute lung injury (ALI) causes acute respiratory distress syndrome, with a high mortality rate of 40%, with currently available pharmacological treatments. Cytosolic phospholipase A2 (cPLA2) plays a critical role in the lipopolysaccharide (LPS)-induced pathology of ALI. This study assessed the therapeutic effects of fexofenadine (FFD), an on-market small-molecule drug that can target cPLA2 in LPS-induced ALI.

METHODS

Primary macrophages obtained from the bone marrow of wild-type and cPLA2 knockout mice and the alveolar macrophage cell line, MHS were used to test the inhibitory effect of FFD on the cPLA2/ERK/p65 signaling pathway, NF-κB p65 translocation, and cytokine and chemokine production. An LPS-induced ALI mouse model was used to assess the treatment effects of FFD. Flow cytometry detected subsets of macrophages and neutrophils. cPLA2 activity and downstream hydrolysates were detected. Treatment with a cPLA2 inhibitor or NF-κB p65 inhibitor confirmed that FFD functioned through the cPLA2/ERK/p65 signaling pathway by targeting cPLA2.

RESULTS

FFD reduced the infiltration of macrophages and neutrophils, decreased the protein secretion in bronchoalveolar lavage fluid, and reduced the production of TNFα, IL-1β, IL-6, MCP-1, and IL-8 in the lung, bronchoalveolar lavage fluid, and sera of LPS-induced ALI mice. FFD inhibited cPLA2 activity, suppressed the cPLA2/ERK/p65 signaling pathway, inhibited translocation of p65, and decreased the production of cytokines, chemokines, and downstream hydrolysates of cPLA2, arachidonic acid, and leukotriene B4.

CONCLUSION

FFD inhibits the cPLA2/ERK/p65 signaling pathway by targeting cPLA2. Therefore, FFD is promising as a therapeutic against cPLA2-involved diseases, particularly ALI.

Calcium-sensing receptor-mediated NLRP3 inflammasome activation in rheumatoid arthritis and autoinflammation

The calcium-sensing receptor (CaSR) is expressed in many cell types - including immune cells and in particular circulating monocytes. Here, the receptor plays an important physiological role as a regulator of constitutive macropinocytosis. This review article provides an overview of the literature on the role of the calcium sensing receptor in the context of inflammatory processes. Special emphasis is laid upon the importance for monocytes in the context of rheumatoid arthritis. We have shown previously, that stimulation of the receptor by increased extracellular Ca²⁺ ([Ca²⁺]_ex) triggers a pro-inflammatory response due to NLRP3 inflammasome assembly and interleukin (IL)-1β release. The underlying mechanism includes macropinocytosis of calciprotein particles (CPPs), which are taken up in a [Ca²⁺]_ex-induced, CaSR dependent manner, and leads to strong IL-1β release. In rheumatoid arthritis (RA), this uptake and the resulting IL-1β release is significantly increased due to increased expression of the receptor. Moreover, increased [Ca²⁺]_ex-induced CPP uptake and IL-1β release is associated with more active disease, while CaSR overexpression has been reported to be associated with cardiovascular complications of RA. Most importantly, however, in animal experiments with arthritic mice, increased local calcium concentrations are present, which in combination with release of fetuin-A from eroded bone could contribute to formation of CPPs. We propose, that increased [Ca²⁺]_ex, CPPs and pro-inflammatory cytokines drive a vicious cycle of inflammation and bone destruction which in turn offers new potential therapeutic approaches.

The role of calcium-sensitive receptor in ovalbumin-induced airway inflammation and hyperresponsiveness in juvenile mice with asthma

The role of the calcium-sensitive receptor (CaSR) was assessed in a juvenile mouse model of asthma induced by ovalbumin (OVA). The experiment was divided into normal control, OVA, and OVA +2.5/5 mg/kg NPS2143 (a CaSR antagonist) groups. OVA induction was performed in all groups except the normal control, followed by assessing airway hyperresponsiveness (AHR) and lung pathological changes. Serum OVA-specific IgE and IgG1 were detected with an enzyme-linked immunosorbent assay (ELISA), and inflammatory cells were counted in bronchoalveolar lavage fluid (BALF). Real-time quantitative polymerase chain reaction, ELISA, and western blotting were performed to detect gene and protein expression. NPS2143 improved the OVA-induced AHR in mice, and AHR was higher in the OVA +2.5 mg/kg NPS2143 group than in the OVA +5 mg/kg NPS2143 group. Furthermore, NPS2143 reduced the production of OVA-specific IgE and IgG1 in serum and the number of eosinophils and lymphocytes in BALF in OVA mice with reduced CaSR expression in lung tissues. Besides, OVA-induced mice exhibited peribronchial and perivascular inflammatory cell infiltration, which was accompanied by severe goblet cell hyperplasia/hyperplasia and airway mucus hypersecretion. Furthermore, these mice exhibited increased levels of Interleukin (IL)-5, IL-13, MCP-1, and eotaxin, which were alleviated by NPS2143. The 5 mg/kg NPS2143 showed more effective than the 2.5 mg/kg treatment. CaSR expression was elevated in the lung tissues of OVA-induced asthmatic juvenile mice, whereas the CaSR antagonist NPS2143 reduced AHR and attenuated the inflammatory response in OVA-induced juvenile mice, possibly exerting therapeutic effects on childhood asthma.

The calcium-sensing receptor in inflammation: Recent updates

The Calcium-Sensing Receptor (CaSR) is a member of the class C of G-proteins coupled receptors (GPCRs), it plays a pivotal role in calcium homeostasis by directly controlling calcium excretion in the kidneys and indirectly by regulating parathyroid hormone (PTH) release from the parathyroid glands. The CaSR is found to be ubiquitously expressed in the body, playing a plethora of additional functions spanning from fluid secretion, insulin release, neuronal development, vessel tone to cell proliferation and apoptosis, to name but a few. The present review aims to elucidate and clarify the emerging regulatory effects that the CaSR plays in inflammation in several tissues, where it mostly promotes pro-inflammatory responses, with the exception of the large intestine, where contradictory roles have been recently reported. The CaSR has been found to be expressed even in immune cells, where it stimulates immune response and chemokinesis. On the other hand, CaSR expression seems to be boosted under inflammatory stimulus, in particular, by pro-inflammatory cytokines. Because of this, the CaSR has been addressed as a key factor responsible for hypocalcemia and low levels of PTH that are commonly found in critically ill patients under sepsis or after burn injury. Moreover, the CaSR has been found to be implicated in autoimmune-hypoparathyroidism, recently found also in patients treated with immune-checkpoint inhibitors. Given the tight bound between the CaSR, calcium and vitamin D metabolism, we also speculate about their roles in the pathogenesis of severe acute respiratory syndrome coronavirus-19 (SARS-COVID-19) infection and their impact on patients' prognosis. We will further explore the therapeutic potential of pharmacological targeting of the CaSR for the treatment and management of aberrant inflammatory responses.

Macrophages in obesity are characterised by increased IL-1β response to calcium-sensing receptor signals

Objective

Obesity is complicated by inflammatory activation of the innate immune system. Stimulation of the calcium-sensing receptor (CaSR) by extra-cellular calcium ions ([Ca²⁺]_ex) can trigger NLRP3 inflammasome activation and inflammation. We hypothesised, that this mechanism might contribute to the activation of adipose tissue (AT) in obesity, and investigated [Ca²⁺]_ex-induced, CaSR mediated IL-1β release by macrophages in obesity.

Methods

[Ca²⁺]_ex-induced IL-1β release was investigated in monocyte-derived macrophages (MDM) generated from peripheral blood of patients with obesity and from normal-weight controls. Visceral and subcutaneous AT biosamples were stimulated with [Ca²⁺]_ex, and IL-1β release, as well as expression of NLRP3 inflammasome and cytokine genes, was determined.

Results

Both MDM and AT readily responded with concentration-dependent IL-1β release already at low, near physiological concentrations to addition of [Ca²⁺]_ex, which was more than 80 fold higher than the LPS-induced effect. IL-1β levels induced by [Ca²⁺]_ex were significantly higher not only in MDM from patients with obesity compared to controls, but also in visceral versus subcutaneous AT. This fat-depot difference was also reflected by mRNA expression levels of inflammasome and cytokine genes.

Conclusions

Obesity renders macrophages more susceptible to [Ca²⁺]_ex-induced IL-1β release and pyroptosis. Increased susceptibility was independent of the response to LPS and circulating CRP arguing against mere pro-inflammatory pre-activation of monocytes. Instead, we propose that CaSR mediated signalling is relevant for the deleterious innate immune activation in obesity.

A role for the calcium-sensing receptor in the expression of inflammatory mediators in LPS-treated human dental pulp cells

The aim of this study is to investigate the role of calcium-sensing receptor (CaSR) in the expression of inflammatory mediators of lipopolysaccharide (LPS)-treated human dental pulp cells (hDPCs). The expression profile of CaSR in LPS-simulated hDPCs was detected using immunofluorescence, real time quantitative PCR (RT-qPCR), and Western blot analyses. Then, its regulatory effects on the expression of specific inflammatory mediators such as interleukin (IL)-1β, IL-6, cyclooxygenase 2 (COX2)-derived prostaglandin E2 (PGE₂), tumor necrosis factor (TNF)-α, and IL-10 were determined by RT-qPCR and enzyme-linked immunosorbent assay (ELISA). LPS significantly downregulated the gene expression of CaSR, but upregulated its protein expression level in hDPCs. Treatments by CaSR agonist R568 or its antagonist Calhex231, and their combinations with protein kinase B (AKT) inhibitor LY294002 showed obvious effects on the expression of selected inflammatory mediators in a time-dependent manner. Meanwhile, an opposite direction was found between the action of R568 and Calhex231, as well as the expression of the pro- (IL-1β, IL-6, COX2-derived PGE₂, and TNF-α) and anti-inflammatory (IL-10) mediators. The results provide the first evidence that CaSR-phosphatidylinositol-3 kinase (PI3K)-AKT-signaling pathway is involved in the release of inflammatory mediators in LPS-treated hDPCs, suggesting that the activation or blockade of CaSR may provide a novel therapeutic strategy for the treatment of pulp inflammatory diseases.

Topical therapy with negative allosteric modulators of the calcium-sensing receptor (calcilytics) for the management of asthma: the beginning of a new era?

In this review article we present the evidence to date supporting the role of the calcium-sensing receptor (CaSR) as a key, pluripotential molecular trigger for asthma and speculate on the likely benefits of topical therapy of asthma with negative allosteric modulators of the CaSR: calcilytics.

Methyl p‑hydroxycinnamate exerts anti‑inflammatory effects in mouse models of lipopolysaccharide‑induced ARDS

Methyl p-hydroxycinnamate (MH), an esterified derivative of p-Coumaric acid exerts anti-inflammatory effects on lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Based on these effects, the present study investigated the protective role of MH in a mouse model of LPS-induced acute respiratory distress syndrome (ARDS). The results demonstrated that administration of LPS (5 mg/kg intranasally) markedly increased the neutrophil/macrophage numbers and levels of inflammatory molecules (TNF-α, IL-6, IL-1β and reactive oxygen species) in the bronchoalveolar lavage fluid (BALF) of mice. On histological examination, the presence of inflammatory cells was observed in the lungs of mice administered LPS. LPS also notably upregulated the secretion of monocyte chemoattractant protein-1 and protein content in BALF as well as expression of inducible nitric oxide synthase in the lungs of mice; it also caused activation of p38 mitogen-activated protein kinase (MAPK) and NF-κB signaling. However, MH treatment significantly suppressed LPS-induced upregulation of inflammatory cell recruitment, inflammatory molecule levels and p38MAPK/NF-κB activation, and also led to upregulation of heme oxygenase-1 (HO-1) expression in the lungs of mice. In addition, the ability of MH to induce HO-1 expression was confirmed in RAW264.7 macrophages. Taken together, the findings of the present study indicated that MH may exert protective effects against airway inflammation in ARDS mice by inhibiting inflammatory cell recruitment and the production of inflammatory molecules.

Therapeutic Opportunities of Targeting Allosteric Binding Sites on the Calcium-Sensing Receptor

The CaSR is a class C G protein-coupled receptor (GPCR) that acts as a multimodal chemosensor to maintain diverse homeostatic functions. The CaSR is a clinical therapeutic target in hyperparathyroidism and has emerged as a putative target in several other diseases. These include hyper- and hypocalcaemia caused either by mutations in the CASR gene or in genes that regulate CaSR signaling and expression, and more recently in asthma. The development of CaSR-targeting drugs is complicated by the fact that the CaSR possesses many different binding sites for endogenous and exogenous agonists and allosteric modulators. Binding sites for endogenous and exogenous ligands are located throughout the large CaSR protein and are interconnected in ways that we do not yet fully understand. This review summarizes our current understanding of CaSR physiology, signaling, and structure and how the many different binding sites of the CaSR may be targeted to treat disease.

Decreased monocyte calcium sensing receptor expression in patients with chronic kidney disease is associated with impaired monocyte ability to reduce vascular calcification

In chronic kidney disease (CKD), calcium-sensing receptor (CaSR) expression and function have been extensively studied in parathyroid tissue and vascular tissues. To examine whether similar changes occurred in other tissues, we measured total and surface CaSR expression in monocytes of patients with various stages of CKD and healthy volunteers respectively in cross-sectional studies. We further explored in vitro the impact of uremic serum on CaSR expression in monocytes (U937 and THP-1 cell lines), and whether human peripheral blood mononuclear cells or U937 and THP-1 monocytes might modify vascular calcium deposition in rat carotid arteries in vitro. CKD was associated with a decrease in peripheral blood mononuclear cell CaSR expression both in total and at the monocyte surface alone (43% and 34%, respectively in CKD stages 4-5). This decrease was associated with a reduction in the ability of monocytes to inhibit vascular calcification in vitro. Pretreatment with the calcimimetic NPSR568 of peripheral blood mononuclear cells isolated from patients with CKD significantly improved monocyte capacity to reduce carotid calcification in vitro. The fewer peripheral blood mononuclear cells expressing cell surface CaSR, the more calcimimetic treatment enhanced the decrease of carotid calcium content. Thus, we demonstrate that monocyte CaSR expression is decreased in patients with CKD and provide in vitro evidence for a potential role of this decrease in the promotion of vascular calcification. Hence, targeting this alteration or following monocyte CaSR expression as an accessible marker might represent a promising therapeutic strategy in CKD-associated arterial calcification.

Characterization of Negative Allosteric Modulators of the Calcium-Sensing Receptor for Repurposing as a Treatment of Asthma

Asthma is still an incurable disease, and there is a recognized need for novel small-molecule therapies for people with asthma, especially those poorly controlled by current treatments. We previously demonstrated that calcium-sensing receptor (CaSR) negative allosteric modulators (NAMs), calcilytics, uniquely suppress both airway hyperresponsiveness (AHR) and inflammation in human cells and murine asthma surrogates. Here we assess the feasibility of repurposing four CaSR NAMs, which were originally developed for oral therapy for osteoporosis and previously tested in the clinic as a novel, single, and comprehensive topical antiasthma therapy. We address the hypotheses, using murine asthma surrogates, that topically delivered CaSR NAMs 1) abolish AHR; 2) are unlikely to cause unwanted systemic effects; 3) are suitable for topical application; and 4) inhibit airway inflammation to the same degree as the current standard of care, inhaled corticosteroids, and, furthermore, inhibit airway remodeling. All four CaSR NAMs inhibited poly-L-arginine-induced AHR in naïve mice and suppressed both AHR and airway inflammation in a murine surrogate of acute asthma, confirming class specificity. Repeated exposure to inhaled CaSR NAMs did not alter blood pressure, heart rate, or serum calcium concentrations. Optimal candidates for repurposing were identified based on anti-AHR/inflammatory activities, pharmacokinetics/pharmacodynamics, formulation, and micronization studies. Whereas both inhaled CaSR NAMs and inhaled corticosteroids reduced airways inflammation, only the former prevented goblet cell hyperplasia in a chronic asthma model. We conclude that inhaled CaSR NAMs are likely a single, safe, and effective topical therapy for human asthma, abolishing AHR, suppressing airways inflammation, and abrogating some features of airway remodeling. SIGNIFICANCE STATEMENT: Calcium-sensing receptor (CaSR) negative allosteric modulators (NAMs) reduce airway smooth muscle hyperresponsiveness, reverse airway inflammation as efficiently as topical corticosteroids, and suppress airway remodeling in asthma surrogates. CaSR NAMs, which were initially developed for oral therapy of osteoporosis proved inefficacious for this indication despite being safe and well tolerated. Here we show that structurally unrelated CaSR NAMs are suitable for inhaled delivery and represent a one-stop, steroid-free approach to asthma control and prophylaxis.

K2P2.1 (TREK-1) potassium channel activation protects against hyperoxia-induced lung injury

No targeted therapies exist to counteract Hyperoxia (HO)-induced Acute Lung Injury (HALI). We previously found that HO downregulates alveolar K_2P2.1 (TREK-1) K⁺ channels, which results in worsening lung injury. This decrease in TREK-1 levels leaves a subset of channels amendable to pharmacological intervention. Therefore, we hypothesized that TREK-1 activation protects against HALI. We treated HO-exposed mice and primary alveolar epithelial cells (AECs) with the novel TREK-1 activators ML335 and BL1249, and quantified physiological, histological, and biochemical lung injury markers. We determined the effects of these drugs on epithelial TREK-1 currents, plasma membrane potential (Em), and intracellular Ca²⁺ (iCa) concentrations using fluorometric assays, and blocked voltage-gated Ca²⁺ channels (Ca_V) as a downstream mechanism of cytokine secretion. Once-daily, intra-tracheal injections of HO-exposed mice with ML335 or BL1249 improved lung compliance, histological lung injury scores, broncho-alveolar lavage protein levels and cell counts, and IL-6 and IP-10 concentrations. TREK-1 activation also decreased IL-6, IP-10, and CCL-2 secretion from primary AECs. Mechanistically, ML335 and BL1249 induced TREK-1 currents in AECs, counteracted HO-induced cell depolarization, and lowered iCa²⁺ concentrations. In addition, CCL-2 secretion was decreased after L-type Ca_V inhibition. Therefore, Em stabilization with TREK-1 activators may represent a novel approach to counteract HALI.

Effects of pharmacological calcimimetics on colorectal cancer cells over-expressing the human calcium-sensing receptor

The calcium-sensing receptor (CaSR) is a ubiquitously expressed multifunctional G protein-coupled receptor. Several studies reported that the CaSR plays an anti-inflammatory and anti-tumorigenic role in the intestine, and that it is down-regulated during colorectal carcinogenesis. We hypothesized that positive allosteric CaSR modulators (type II calcimimetics) selectively targeting the intestinal cells could be used for the treatment of intestinal pathologies. Therefore, the aim of this study was to determine the effect of pharmacological stimulation of CaSR on gene expression in vitro and on tumor growth in vivo. We stably transduced two colon cancer cell lines (HT29 and Caco2) with lentiviral vectors containing either the CaSR fused to GFP or GFP only. Using RNA sequencing, RT-qPCR experiments and ELISA, we determined that CaSR over-expression itself had generally little effect on gene expression in these cells. However, treatment with 1 μM of the calcimimetic NPS R-568 increased the expression of pro-inflammatory factors such as IL-23α and IL-8 and reduced the transcription of various differentiation markers in the cells over-expressing the CaSR. In vivo, neither the presence of the CaSR nor p.o. treatment of the animals with the calcimimetic cinacalcet affected tumor growth, tumor cell proliferation or tumor vascularization of murine HT29 xenografts. In summary, CaSR stimulation in CaSR over-expressing cells enhanced the expression of inflammatory markers in vitro, but was not able to repress colorectal cancer tumorigenicity in vivo. These findings suggest potential pro-inflammatory effects of the CaSR and type II calcimimetics in the intestine.

Aberrant upregulation of CaSR promotes pathological new bone formation in ankylosing spondylitis

Pathological new bone formation is a typical pathological feature in ankylosing spondylitis (AS), and the underlying molecular mechanism remains elusive. Previous studies have shown that the calcium‐sensing receptor (CaSR) is critical for osteogenic differentiation while also being highly involved in many inflammatory diseases. However, whether it plays a role in pathological new bone formation of AS has not been reported. Here, we report the first piece of evidence that expression of CaSR is aberrantly upregulated in entheseal tissues collected from AS patients and animal models with different hypothetical types of pathogenesis. Systemic inhibition of CaSR reduced the incidence of pathological new bone formation and the severity of the ankylosing phenotype in animal models. Activation of PLCγ signalling by CaSR promoted bone formation both in vitro and in vivo. In addition, various inflammatory cytokines induced upregulation of CaSR through NF‐κB/p65 and JAK/Stat3 pathways in osteoblasts. These novel findings suggest that inflammation‐induced aberrant upregulation of CaSR and activation of CaSR‐PLCγ signalling in osteoblasts act as mediators of inflammation, affecting pathological new bone formation in AS.

The Anti-Inflammatory Effect of Trichilia martiana C. DC. in the Lipopolysaccharide-Stimulated Inflammatory Response in Macrophages and Airway Epithelial Cells and in LPS-Challenged Mice

A number of species of the genus Trichilia (Meliaceae) exhibit anti-inflammatory effects. However, the effect of Trichilia martiana C. DC. (TM) on lipopolysaccharide (LPS)-induced inflammation has not, to the best of our knowledge, yet been determined. Therefore, in the present study, the antiinflammatory effect of TM on LPS-stimulated RAW264.7 macrophages was evaluated. The ethanol extract of TM (TMEE) significantly inhibited LPS-induced nitric oxide (NO), prostaglandin 2 (PGE₂), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). TMEE also reduced the levels of inflammatory cytokines, including tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β and IL-6. The upregulation of mitogen-activated protein kinases (MAPKs) and NF-κB activation was revealed to be downregulated following TMEE pretreatment. Furthermore, TMEE was indicated to lead to the nucleus translocation of nuclear factor erythroid-derived 2-related factor 2 (Nrf2) and the expression of heme oxygenase-1 (HO-1). In H292 airway epithelial cells, the pretreatment of TMEE significantly downregulated the production of LPS-stimulated IL-1β, and TMEE was indicated to increase the expression of HO-1. In animal models exhibiting LPS-induced acute lung injury (ALI), treatment with TMEE reduced the levels of macrophages influx and TNF-α production in the bronchoalveolar lavage fluid (BALF) of ALI mice. Additionally, TMEE significantly downregulated the activation of ERK, JNK and IκB, and upregulated the expression of HO-1 in the lungs of ALI mice. In conclusion, the results of the current study demonstrated that TMEE could exert a regulatory role in the prevention or treatment of the endotoxin-mediated inflammatory response.

Danger-Sensing/Patten Recognition Receptors and Neuroinflammation in Alzheimer's Disease

Fibrillar aggregates and soluble oligomers of both Amyloid-β peptides (Aβs) and hyperphosphorylated Tau proteins (p-Tau-es), as well as a chronic neuroinflammation are the main drivers causing progressive neuronal losses and dementia in Alzheimer’s disease (AD). However, the underlying pathogenetic mechanisms are still much disputed. Several endogenous neurotoxic ligands, including Aβs, and/or p-Tau-es activate innate immunity-related danger-sensing/pattern recognition receptors (PPRs) thereby advancing AD’s neuroinflammation and progression. The major PRR families involved include scavenger, Toll-like, NOD-like, AIM2-like, RIG-like, and CLEC-2 receptors, plus the calcium-sensing receptor (CaSR). This quite intricate picture stresses the need to identify the pathogenetically topmost Aβ-activated PRR, whose signaling would trigger AD’s three main drivers and their intra-brain spread. In theory, the candidate might belong to any PRR family. However, results of preclinical studies using in vitro nontumorigenic human cortical neurons and astrocytes and in vivo AD-model animals have started converging on the CaSR as the pathogenetically upmost PRR candidate. In fact, the CaSR binds both Ca²⁺ and Aβs and promotes the spread of both Ca²⁺ dyshomeostasis and AD’s three main drivers, causing a progressive neurons’ death. Since CaSR’s negative allosteric modulators block all these effects, CaSR’s candidacy for topmost pathogenetic PRR has assumed a growing therapeutic potential worth clinical testing.

Prokineticin 2 via Calcium-Sensing Receptor Activated NLRP3 Inflammasome Pathway in the Testicular Macrophages of Uropathogenic Escherichia coli-Induced Orchitis

Reproductive tract infections contribute to the development of testicular inflammatory lesions, leading to male infertility. Previous research shows that the activation of the NLRP3 inflammasome in orchitis promotes the secretion and maturation of IL-1β and, thus, decreases male fertility. The calcium-sensing receptor (CaSR) is closely related to the secretion of proinflammatory cytokines. An increase in the CaSR level promotes the assembly and activation of the NLRP3 inflammasome. However, the role of CaSRs in orchitis is unknown. We first constructed a uropathogenic Escherichia Coli (UPEC) rat orchitis model and then detected the expression of CaSR and NLRP3 inflammatory pathway proteins in testicular macrophages (TM) through RT-PCR and WB, calcium levels in TM through flow cytometry, and proinflammatory factor IL-1β through ELISA. In addition, testosterone levels in the serum samples were detected using liquid chromatography–mass spectrometry (LC-MS). Here, we show that CaSR upregulation after infection in TM in a rat model of UPEC induces the activation of the NLRP3 inflammasome pathway and thereby enhances IL-1β secretion and reduces the testosterone level in the blood. Moreover, CaSR inhibitors can alleviate inflammatory impairment. After UPEC challenge in vitro, CaSR promoted NLRP3 expression and released IL-1β cleaved from TM into the supernatant. Overall, elevated CaSR levels in TM in testes with UPEC-induced orchitis may impair testosterone synthesis through the activation of the NLRP3 pathway and PK2 is an upstream regulatory protein of CaSR. Our research further shows the underlying mechanisms of inflammation-related male infertility and provides anti-inflammatory therapeutic targets for male infertility.

Calcium-sensing receptor-mediated NLRP3 inflammasome response to calciprotein particles drives inflammation in rheumatoid arthritis

Increased extracellular Ca2+ concentrations ([Ca2+]ex) trigger activation of the NLRP3 inflammasome in monocytes through calcium-sensing receptor (CaSR). To prevent extraosseous calcification in vivo, the serum protein fetuin-A stabilizes calcium and phosphate into 70-100 nm-sized colloidal calciprotein particles (CPPs). Here we show that monocytes engulf CPPs via macropinocytosis, and this process is strictly dependent on CaSR signaling triggered by increases in [Ca2+]ex. Enhanced macropinocytosis of CPPs results in increased lysosomal activity, NLRP3 inflammasome activation, and IL-1β release. Monocytes in the context of rheumatoid arthritis (RA) exhibit increased CPP uptake and IL-1β release in response to CaSR signaling. CaSR expression in these monocytes and local [Ca2+] in afflicted joints are increased, probably contributing to this enhanced response. We propose that CaSR-mediated NLRP3 inflammasome activation contributes to inflammatory arthritis and systemic inflammation not only in RA, but possibly also in other inflammatory conditions. Inhibition of CaSR-mediated CPP uptake might be a therapeutic approach to treating RA.

CaSR Antagonist (Calcilytic) NPS 2143 Hinders the Release of Neuroinflammatory IL-6, Soluble ICAM-1, RANTES, and MCP-2 from Aβ-Exposed Human Cortical Astrocytes

Available evidence shows that human cortical neurons’ and astrocytes’ calcium-sensing receptors (CaSRs) bind Amyloid-beta (Aβ) oligomers triggering the overproduction/oversecretion of several Alzheimer’s disease (AD) neurotoxins—effects calcilytics suppress. We asked whether Aβ•CaSR signaling might also play a direct pro-neuroinflammatory role in AD. Cortical nontumorigenic adult human astrocytes (NAHAs) in vitro were untreated (controls) or treated with Aβ_25–35 ± NPS 2143 (a calcilytic) and any proinflammatory agent in their protein lysates and growth media assayed via antibody arrays, enzyme-linked immunosorbent assays (ELISAs), and immunoblots. Results show Aβ•CaSR signaling upregulated the synthesis and release/shedding of proinflammatory interleukin (IL)-6, intercellular adhesion molecule-1 (ICAM-1) (holoprotein and soluble [s] fragment), Regulated upon Activation, normal T cell Expressed and presumably Secreted (RANTES), and monocyte chemotactic protein (MCP)-2. Adding NPS 2143 (i) totally suppressed IL-6′s oversecretion while remarkably reducing the other agents’ over-release; and (ii) more effectively than Aβ alone increased over controls the four agents’ distinctive intracellular accumulation. Conversely, NPS 2143 did not alter Aβ-induced surges in IL-1β, IL-3, IL-8, and IL-16 secretion, consequently revealing their Aβ•CaSR signaling-independence. Finally, Aβ_25–35 ± NPS 2143 treatments left unchanged MCP-1′s and TIMP-2′s basal expression. Thus, NAHAs Aβ•CaSR signaling drove four proinflammatory agents’ over-release that NPS 2143 curtailed. Therefore, calcilytics would also abate NAHAs’ Aβ•CaSR signaling direct impact on AD’s neuroinflammation.

Notch enhances Ca2+ entry by activating calcium-sensing receptors and inhibiting voltage-gated K+ channels

The increase in cytosolic Ca2+ concentration ([Ca2+]cyt) and upregulation of calcium-sensing receptor (CaSR) and stromal interaction molecule 2 (STIM2) along with inhibition of voltage-gated K+ (KV) channels in pulmonary arterial smooth muscle cells (PASMC) have been implicated in the development of pulmonary arterial hypertension; however, the precise upstream mechanisms remain elusive. Activation of CaSR, a G protein-coupled receptor (GPCR), results in Ca2+ release from the endoplasmic/sarcoplasmic reticulum (ER/SR) and Ca2+ influx through receptor-operated and store-operated Ca2+ channels (SOC). Upon Ca2+ depletion from the SR, STIM forms clusters to mediate store-operated Ca2+ entry. Activity of KV channels, like KCNA5/KV1.5 and KCNA2/KV1.2, contributes to regulating membrane potential, and inhibition of KV channels results in membrane depolarization that increases [Ca2+]cyt by opening voltage-dependent Ca2+ channels. In this study, we show that activation of Notch by its ligand Jag-1 promotes the clustering of STIM2, and clustered STIM2 subsequently enhances the CaSR-induced Ca2+ influx through SOC channels. Extracellular Ca2+-mediated activation of CaSR increases [Ca2+]cyt in CASR-transfected HEK293 cells. Treatment of CASR-transfected cells with Jag-1 further enhances CaSR-mediated increase in [Ca2+]cyt. Moreover, CaSR-mediated increase in [Ca2+]cyt was significantly augmented in cells co-transfected with CASR and STIM2. CaSR activation results in STIM2 clustering in CASR/STIM2-cotransfected cells. Notch activation also induces significant clustering of STIM2. Furthermore, activation of Notch attenuates whole cell K+ currents in KCNA5- and KCNA2-transfected cells. Together, these results suggest that Notch activation enhances CaSR-mediated increases in [Ca2+]cyt by enhancing store-operated Ca2+ entry and inhibits KCNA5/KV1.5 and KCNA2/KV1.2, ultimately leading to voltage-activated Ca2+ entry.

Calcium sensing receptor activation in THP-1 macrophages triggers NLRP3 inflammasome and human preadipose cell inflammation

Excess adipose tissue (AT) associates with inflammation and obesity-related diseases. We studied whether calcium-sensing receptor (CaSR)-mediated NLRP3 inflammasome activation in THP-1 macrophages elevates inflammation in LS14 preadipocytes, modeling deleterious AT cell crosstalk. THP-1 macrophages exposed to cinacalcet (CaSR activator, 2 μM, 4 h) showed elevated proinflammatory marker and NLRP3 inflammasome mRNA, pro-IL-1β protein and caspase-1 activity, whereas preincubation with CaSR negative modulators prevented these effects. The key NLRP3 inflammasome component ASC was silenced (siRNA) in THP-1 cells, and inflammasome activation was evaluated (qPCR, Western blot, caspase-1 activity) or they were further cultured to obtain conditioned medium (CoM). Exposure of LS14 preadipocytes to CoM from cinacalcet-treated THP-1 elevated LS14 proinflammatory cytokine expression, which was abrogated by THP-1 inflammasome silencing. Thus, CaSR activation elevates THP-1-induced inflammation in LS14 preadipocytes, via macrophage NLRP3 inflammasome activation. Modulating CaSR activation may prevent deleterious proinflammatory cell crosstalk in AT, a promising approach in obesity-related metabolic disorders.

Calcium-sensing receptor antagonist NPS-2143 suppresses proliferation and invasion of gastric cancer cells

NPS-2143 is a calcium-sensing receptor (CaSR) antagonist that has been demonstrated to possess anticancer activity. To date, the effects of NPS-2143 on gastric cancer (GC) cell growth, motility, and apoptosis have not been investigated. In the present study, we firstly investigated the expression of CaSR in GC tissues using immunohistochemistry and western blotting. Then Cell Counting Kit-8 and colony formation assays were conducted to explore the effect of the NPS-2143 on the proliferation of GC cell line AGS. Transwell invasion and migration assays were performed to test the effect of NPS-2143 on AGS cell motility. We determined the percentage of apoptotic cells by flow cytometry and explored the changes of apoptosis-related protein by western blotting. Furthermore, we constructed a CaSR knockdown AGS cell line to determine whether NPS-2143 acted via inhibition of CaSR. We found that the protein expression level of CaSR was higher in GC tissues compared with the paired adjacent normal tissues. In addition, NPS-2143 treatment caused an inhibitory effect on the proliferation, invasion, and migration of AGS cells and a promoting effect on AGS apoptosis. The expression of Bcl-2 was decreased while the levels of Bax and active caspase 3 were enhanced in AGS cells after NPS-2143 treatment. Mechanistically, NPS-2143 lead to a significant decrease in the expression of phosphorylated (p)-AKT, phosphorylated mechanistic target of rapamycin (p-mTOR), p70, and cyclin D1. Knockdown of CaSR also suppressed cell proliferation, invasion, and migration and promoted cell apoptosis. No significant difference was observed between CaSR-silenced AGS cells with and without NPS-2143 treatment. These results confirmed that NPS-2143 has an inhibitory influence on AGS cell growth via inhibiting CaSR, which then suppresses the PI3K/Akt signaling pathway.

Microcalcifications, calcium-sensing receptor, and cancer

Calcium stones and calculi are observed in numerous human tissues. They are the result of deposition of calcium salts and are due to high local calcium concentrations. Prostatic calculi are usually classified as endogenous or extrinsic stones. Endogenous stones are commonly caused by obstruction of the prostatic ducts around an enlarged prostate resulting from benign prostatic hyperplasia or from chronic inflammation. The latter occurs mainly around the urethra and is generally caused by reflux of urine into the prostate. Calcium concentrations higher than in the plasma at sites of infection may induce the chemotactic response that eventually leads to recruitment of inflammatory cells. The calcium sensing receptor (CaSR) may be crucial for this recruitment as its expression and activity are increased by cytokines such as IL-6 and high extracellular calcium concentrations, respectively. The links between calcium calculi, inflammation, calcium supplementation, and CaSR functions in prostate cancer patients will be discussed in this review.

Pistacia weinmannifolia ameliorates cigarette smoke and lipopolysaccharide‑induced pulmonary inflammation by inhibiting interleukin‑8 production and NF‑κB activation

Pistacia weinmannifolia (PW) has been used in traditional Chinese medicine to treat headaches, dysentery, enteritis and influenza. However, PW has not been known for treating respiratory inflammatory diseases, including chronic obstructive pulmonary disease (COPD). The present in vitro analysis confirmed that PW root extract (PWRE) exerts anti-inflammatory effects in phorbol myristate acetate- or tumor necrosis factor α (TNF-α)-stimulated human lung epithelial NCI-H292 cells by attenuating the expression of interleukin (IL)-8, IL-6 and Mucin A5 (MUC5AC), which are closely associated with the pulmonary inflammatory response in the pathogenesis of COPD. Thus, the aim of the present study was to evaluate the protective effect of PWRE on pulmonary inflammation induced by cigarette smoke (CS) and lipopoly-saccharide (LPS). Treatment with PWRE significantly reduced the quantity of neutrophils and the levels of inflammatory molecules and toxic molecules, including tumor TNF-α, IL-6, IL-8, monocyte chemoattractant protein-1, neutrophil elastase and reactive oxygen species, in the bronchoalveolar lavage fluid of mice with CS- and LPS-induced pulmonary inflammation. PWRE also attenuated the influx of inflammatory cells in the lung tissues. Furthermore, PWRE downregulated the activation of nuclear factor-κB and the expression of phosphodiesterase 4 in the lung tissues. Therefore, these findings suggest that PWRE may be a valuable adjuvant treatment for COPD.

Anti-inflammatory effects of ethanol extract from the leaves and shoots of Cedrela odorata L. in cytokine-stimulated keratinocytes

Cedrela odorata L. is a native plant of the Amazon region. The bark is used in folk remedies for the treatment of diarrhea, vomiting, fever and inflammation. Atopic dermatitis (AD) is a chronic, relapsing inflammatory skin disease accompanied by itching. It is a complex disease involving environmental factors and genetic factors. In the present study, the anti-inflammatory and anti-allergic effects of C. odorata L. methanol extract (COEE) on tumor necrosis factor (TNF)-α and interferon (IFN)-γ-stimulated HaCaT keratinocyte cells were investigated. ELISA and RT-PCR analysis revealed that the extract had anti-inflammatory effects, and reduced the interleukin (IL)-6 and IL-8 levels of the HaCaT cells. In addition, COEE exhibited anti-allergic effects, comprising a reduction in the thymus and activation-regulated chemokine and macrophage-derived chemokine levels. In addition, pathway analysis and comparison with Bay11-7082 indicated that these effects are due to the inhibition of nuclear factor (NF)-κB in TNF-α/IFN-γ-induced HaCaT cells. Therefore, the results of the present study suggest that COEE has anti-inflammatory and anti-allergic properties in TNF-α and IFN-γ-stimulated HaCaT cells, which are associated with the inhibition of pro-inflammatory cytokines and chemokines via the NF-κB pathway.

Intranasal Application of Budesonide Attenuates Lipopolysaccharide-Induced Acute Lung Injury by Suppressing Nucleotide-Binding Oligomerization Domain-Like Receptor Family, Pyrin Domain-Containing 3 Inflammasome Activation in Mice

Aim

To investigate the protective effects of budesonide against lipopolysaccharide- (LPS-) induced acute lung injury (ALI) in a murine model and its underlying mechanism.

Methods

Adult male C57BL/6 mice were divided into three groups: control, ALI, and ALI + budesonide groups. LPS (5 mg/kg) was intratracheally injected to induce ALI in mice. Budesonide (0.5 mg/kg) was intranasally given 1 h before LPS administration in the ALI + budesonide group. Twelve hours after LPS administration, all mice were sacrificed. Hematoxylin-eosin staining and pathological scores were used to evaluate pathological injury. Bronchoalveolar lavage was performed. The numbers of total cells, neutrophils, and macrophages in the bronchoalveolar lavage fluid (BALF) were counted. Enzyme-linked immunosorbent assay was employed to detect the proinflammatory cytokines in BALF and serum, including tumor necrosis factor- (TNF-) α, monocyte chemoattractant protein- (MCP-) 1, and interleukin- (IL-) 1β. The expression of the nucleotide-binding oligomerization domain-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome was detected by western blotting. A lethal dose of LPS (40 mg/kg, intraperitoneally) was injected to evaluate the effects of budesonide on survival rates.

Results

Budesonide pretreatment dramatically attenuated pathological injury and reduced pathological scores in mice with ALI. Budesonide pretreatment obviously reduced the numbers of total cells, neutrophils, and macrophages in the BALF of mice with ALI. Additionally, budesonide dramatically reduced TNF-α and MCP-1 expression in the BALF and serum of mice with ALI. Budesonide significantly suppressed NLRP3 and pro-caspase-1 expression in the lung and reduced IL-1β content in the BALF, indicating that budesonide inhibited the activation of the NLRP3 inflammasome. Furthermore, we found that budesonide improved the survival rates of mice with ALI receiving a lethal dose of LPS.

Conclusion

Suppression of NLRP3 inflammasome activation in mice via budesonide attenuated lung injury induced by LPS in mice with ALI.

Novel benzofuran derivative DK-1014 attenuates lung inflammation via blocking of MAPK/AP-1 and AKT/mTOR signaling in vitro and in vivo

Benzofuran derivatives have wide range of biological activities as anti-oxidant, anti-inflammatory and anticonvulsant agent. In this study, we investigated whether the novel benzofuran derivative, DK-1014 has the anti-inflammatory effects on macrophage and lung epithelial cells and anti-asthmatic effects on ovalbumin-treated mice. A series of 2-arylbenzofuran analogues were synthesized and evaluated for NO and interleukin-6 (IL-6) inhibition in LPS-stimulated Raw264.7 cells. Of these analogues, compounds 8, 22a, 22d, and 22 f (DK-1014) exhibited notable inhibitory activity with respect to IL-6 and NO production. In particular, compound DK-1014 strongly reduced IL-6, IL-8, and MMP-9 mRNA expression and IL-6, IL-8, and MCP-1 production in phorbol myristate acetate stimulated A549 cells, reduced MAPKs phosphorylation and c-fos translocation, and attenuated AKT, p70S6K and GSK phosphorylation. In vivo experiments were also performed on ovalbumin-sensitized and challenged BALB/c mice. DK-1014 reduced the airway hyperresponsiveness, inflammatory cell counts and cytokine levels (IL-4, 5, 13) in bronchial alveolar lavage fluid (BALF) and immunoglobulin E in serum, and attenuated inflammatory cell infiltration and mucus hypersecretion in lung tissue. These findings indicate that DK-1014 can protect against allergic airway inflammation through the AP-1 and AKT/mTOR pathways and could be useful source for the development of a therapeutic agent for asthma.

Calcium-sensing receptor in colorectal inflammation and cancer: Current insights and future perspectives

The extracellular calcium-sensing receptor (CaSR) is best known for its action in the parathyroid gland and kidneys where it controls body calcium homeostasis. However, the CaSR has different roles in the gastrointestinal tract, where it is ubiquitously expressed. In the colon, the CaSR is involved in controlling multiple mechanisms, including fluid transport, inflammation, cell proliferation and differentiation. Although the expression pattern and functions of the CaSR in the colonic microenvironment are far from being completely understood, evidence has been accumulating that the CaSR might play a protective role against both colonic inflammation and colorectal cancer. For example, CaSR agonists such as dipeptides have been suggested to reduce colonic inflammation, while dietary calcium was shown to reduce the risk of colorectal cancer. CaSR expression is lost in colonic malignancies, indicating that the CaSR is a biomarker for colonic cancer progression. This dual anti-inflammatory and anti-tumourigenic role of the CaSR makes it especially interesting in colitis-associated colorectal cancer. In this review, we describe the clinical and experimental evidence for the role of the CaSR in colonic inflammation and colorectal cancer, the intracellular signalling pathways which are putatively involved in these actions, and the possibilities to exploit these actions of the CaSR for future therapies of colonic inflammation and cancer.

Important roles of the Ca2+-sensing receptor in vascular health and disease

Ca²⁺-sensing receptor (CaSR), a member of G protein-coupled receptor family, is widely expressed in the vascular system, including perivascular neurons, vascular endothelial cells (VECs) and vascular smooth muscle cells (VSMCs). When stimulated, CaSR can further increase the cytosolic Ca²⁺ concentration ([Ca²⁺]_cyt) in two ways: intracellular Ca²⁺ release from endo/sarcoplasmic reticulum (ER/SR) and extracellular Ca²⁺ entry through Ca²⁺-permeable cation channels. In endothelium, increased Ca²⁺ subsequently activate nitric oxide synthase (NOS) and intermediate conductance Ca²⁺-activated K⁺ channels (IKCa), resulting in vasodilation through NOS-mediated NO release or membrane hyperpolarization. In VSMCs, CaSR-induced intracellular Ca²⁺ increase causes blood vessel constriction. CaSR activation predominantly induces vasorelaxation of whole vascular tissues through VECs-dependent mechanisms; however, CaSR-induced Ca²⁺ signaling in VSMCs may play a braking role in CaSR-mediated vasorelaxation. Emerging evidence reveals the importance of CaSR in the regulation of vascular tone and blood pressure. Here, we summarized recent advances in CaSR-mediated vascular reaction and the underlying mechanisms in different species, including humans. In addition, several studies have demonstrated that CaSR dysfunction may be associated with some fatal vascular diseases, such as pulmonary arterial hypertension, primary hypertension, diabetes, acute myocardial infarction and vascular calcification. With the advance of studies on CaSR in vascular health and disease, it is expected positive modulators or negative modulators of CaSR used for the treatment of specific diseases may be promising therapeutic options for the prevention and/or treatment of vascular diseases.