Calcium-Sensing Receptor in Human Peripheral Blood T Lymphocytes Is Involved in the AMI Onset and Progression through the NF-κB Signaling Pathway

Calcium-sensing receptor and NF-κB pathways in TN breast cancer contribute to cancer-induced cardiomyocyte damage via activating neutrophil extracellular traps formation

Cardiovascular disorders are commonly prevalent in cancer patients, yet the mechanistic link between them remains poorly understood. Because neutrophil extracellular traps (NETs) have implications not just in cardiovascular diseases (CVD), but also in breast cancer (BC), it was hypothesized to contribute to CVD in the context of oncogenesis. We established a mouse model using nude mice to simulate liver metastasis of triple-negative BC (TNBC) through the injection of MDA-MB-231 cells. Multiple imaging and analysis techniques were employed to assess the cardiac function and structure, including echocardiography, HE staining, Masson staining, and transmission electron microscopy (TEM). MDA-MB-231 cells underwent treatment with a CaSR inhibitor, CaSR agonist, and NF-κB channel blocker. The phosphorylation of NF-κB channel protein p65 and the expression and secretion of IL-8 were assessed using qRT-PCR, Western Blot, and ELISA, respectively. In addition, MDA-MB-231 cells were co-cultured with polymorphonuclear neutrophils (PMN) under varying conditions. The co-localization of PMN extracellular myeloperoxidase (MPO) and DNA were observed by cellular immunofluorescence staining to identify the formation of NETs. Then, the cardiomyocytes were co-cultured with the above medium that contains NETs or not, respectively; the effects of NETs on cardiomyocytes apoptosis were perceived by flow cytometry. The ultrastructural changes of myocardial cells were perceived by TEM, and ELISA detected the levels of myocardial enzyme (LDH, MDA and SOD). Overall, according to our research, CaSR has been found to have a regulatory role in IL-8 secretion in MDA-MB-231 cells, as well as in the formation of NETs by PMN cells. These findings suggest CaSR-mediated stimulation in PMN can lead to increased NETs formation and subsequently to cytotoxicity in cardiomyocytes, which potentially via activation of the NF-κB signaling cascade of BC cell.

LIMD2 is the Signature of Cell Aging-immune/Inflammation in Acute Myocardial Infarction

BACKGROUND

Acute myocardial infarction (AMI) is an age-dependent cardiovascular disease in which cell aging, immunity, and inflammatory factors alter the course; however, cell aging-immune/inflammation signatures in AMI have not been investigated.

METHODS

Based on the GEO database to obtain microRNA (miRNA) sequencing, mRNA sequencing and single-cell sequencing data, and utilizing the Seurat package to identify AMI-associated cellular subpopulations. Subsequently, differentially expressed miRNAs and mRNAs were screened to establish a network of competing endogenous RNAs (ceRNAs). Senescence and immunity scores were calculated by single sample gene set enrichment analysis (ssGSEA), ESTIMATE and CIBERSORT algorithms, and the Hmisc package was used to screen for genes with the highest correlation with senescence and immunity scores. Finally, protein-protein interaction (PPI) and molecular docking analyses were performed to predict potential therapeutic agents for the treatment of AMI.

RESULTS

Four cell types (Macrophage, Fibroblast, Endothelial cells, CD8 T cells) were identified in AMI, and CD8 T cells exhibited the lowest cell aging activity. A ceRNA network of miRNAs- mNRA interactions was established based on the overlapping genes in differentially expressed miRNAs (DEmiRNAs) target genes and differentially expressed mRNAs (DEmRNAs). Twenty-four marker genes of CD8 T cells were observed. LIMD2 was identified as cell aging- immune/inflammation-related hub gene in AMI. This study also identified a potential therapeutic network of DB03276-LIMD2-AMI, which showed excellent and stable binding status between DB03276-LIMD2.

CONCLUSION

This study identified LIMD2 as a cell aging-immune/inflammation-related hub gene. The understanding of the pathogenesis and therapeutic mechanisms of AMI was enriched by the ceRNA network and DB03276-LIMD2-LAMI therapeutic network.

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 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.

Calcium-Sensing Receptor (CaSR)-Mediated Intracellular Communication in Cardiovascular Diseases

The calcium-sensing receptor (CaSR), a G-protein-coupled receptor (GPCR), is a cell-surface-located receptor that can induce highly diffusible messengers (IP3, Ca²⁺, cAMP) in the cytoplasm to activate various cellular responses. Recently, it has also been suggested that the CaSR mediates the intracellular communications between the endoplasmic reticulum (ER), mitochondria, nucleus, protease/proteasome, and autophagy-lysosome, which are involved in related cardiovascular diseases. The complex intracellular signaling of this receptor challenges it as a valuable therapeutic target. It is, therefore, necessary to understand the mechanisms behind the signaling characteristics of this receptor in intracellular communication. This review provides an overview of the recent research progress on the various regulatory mechanisms of the CaSR in related cardiovascular diseases and the heart-kidney interaction; the associated common causes are also discussed.

Calcium-Sensing Receptor of Immune Cells and Diseases

Calcium-sensing receptor (CaSR), which was initially found in the parathyroid gland, is ubiquitously expressed and exerts specific functions in multiple cells, including immune cells. CaSR is functionally expressed on neutrophils, monocytes/macrophages, and T lymphocytes, but not B lymphocytes, and regulates cell functions, such as cytokine secretion, chemotaxis, phenotype switching, and ligand delivery. In these immune cells, CaSR is involved in the development of many diseases, such as sepsis, cryopyrin-associated periodic syndromes, rheumatism, myocardial infarction, diabetes, and peripheral artery disease. Since its discovery, it has been controversial whether CaSR is expressed and plays a role in immune cells. This article reviews current knowledge of the role of CaSR in immune cells.

Exosomes Released from CaSR-Stimulated PMNs Reduce Ischaemia/Reperfusion Injury

Ischemia-reperfusion (I/R) injury caused by acute myocardial infarction (AMI) can initiate a strong inflammatory response. Polymorphonuclear cells (PMNs) are the most important inflammatory cells. Our previous studies found that the calcium-sensing receptor (CaSR) regulates the proinflammatory effects of PMNs. However, the role and mechanism of CaSR-regulated PMNs in I/R injury remain uncertain. A rat AMI model was developed in this study and showed that the expression of CaSR on PMNs increased in AMI; however, the levels of Bcl-xl and SOD in myocardial tissue decreased, while Bax and MDA levels increased. Then, after coculture with CaSR-stimulated PMNs, the expression of Bcl-xl in cardiomyocytes significantly increased, Bax expression and the apoptotic rate decreased, and ROS production was significantly inhibited. At the same time, the cardiomyocyte damage caused by hypoxia-reoxygenation was reduced. Furthermore, we found that exosomes derived from PMNs could be taken up by cardiomyocytes. Additionally, the exosomes secreted by CaSR-stimulated PMNs had the same effect on cardiomyocytes as CaSR-stimulated PMNs, while the increased phosphorylation level of AKT in cardiomyocytes could be revered by AKT transduction pathway inhibitors. Subsequently, we identified the exosomes derived from CaSR-stimulated PMNs by second-generation sequencing technology, and increased expression of lncRNA ENSRNOT00000039868 was noted. The data show that this lncRNA can prevent the hypoxia-reoxygenation injury by upregulating the expression of PDGFD in cardiomyocytes. In vivo, exosomes from CaSR-stimulated PMNs played a significant role against AMI and reperfusion injury in myocardial tissue. Thus, we propose that exosomes derived from CaSR-stimulated PMNs can reduce I/R injury in AMI, and this effect may be related to the AKT signaling pathway.

Therapeutic and Diagnostic Value of Caspase-12 and Study of Growth Differentiation Factor-15 in Patients with Acute Myocar-dial Infarction

Background:

To investigate the therapeutic and diagnostic value of caspase-12 and study of growth differentiation factor-15 (GDF-15) in patients with acute myocardial infarction (AMI).

Methods:

Overall, 78 patients with AMI admitted to Weifang People's Hospital Brain Hospital, Weifang, China from Apr 2016 to Apr 2019 were enrolled as AMI group. Seventy-five non-AMI people undergoing physical examination during the same period were enrolled as non-AMI group. The expression levels of caspase-12 and GDF-15 were detected and compared. The correlation between the expressions of GDF-15, caspase-12 and clinical characteristics and efficacy was detected. Single and combined detection of GDF-15 and caspase-12 were performed analyze their role in the early diagnosis, the prediction of efficacy, and the guidance of clinical therapy.

Results:

After treatment, the levels of GDF-15 and caspase-12 in AMI group were significantly lower than those before treatment (P<0.001). The expression levels of GDF-15 and caspase-12 were significantly correlated with blood pressure (P<0.05). The expression levels of GDF-15 and caspase-12 were significantly negatively correlated with clinical efficacy in AMI group. The diagnostic value of combined detection of GDF-15 and caspase-12 was higher than that of single diagnosis. The levels of serum caspase-12 and GDF-15 proteins were significantly up regulated in AMI patients. With the better therapeutic effect, the levels of serum caspase-12 and GDF-15 proteins decreased significantly.

Conclusion:

The levels of serum caspase-12 and GDF-15 proteins may be a key indicator in the clinical diagnosis of acute myocardial infarction and may be used to guide the treatment of AMI patients and predict the therapeutic efficacy.

Correlations and Prognostic Roles of the Nutritional Status and Neutrophil-to-lymphocyte Ratio in Elderly Patients with Acute Myocardial Infarction Undergoing Primary Coronary Intervention

The prognostic capacities of nutritional status and inflammation in patients with acute myocardial infarction (AMI) have attracted increasing interest. However, the combined usefulness of the Controlling Nutritional Status (CONUT) score and neutrophil-to-lymphocyte ratio (NLR) in predicting adverse outcomes has not been investigated. The aim of our study was to investigate the relationship between the CONUT score and the NLR in patients with AMI and assessing the potential of these factors as prognostic markers.In this retrospective study, we reviewed the medical records of consecutive patients aged 65 years or older who were diagnosed with AMI and who underwent primary coronary intervention. We assessed the nutritional and inflammatory statuses using the CONUT score and the NLR, respectively. The NLR and CONUT score in the major adverse cardiovascular event (MACE) (+) patients were significantly higher than those in the MACE (-) patients. The areas under the receiver operating characteristic curves of the NLR and CONUT score were 0.71 and 0.77, respectively. The Kaplan-Meier analysis showed that patients with a high NLR (≥6.07) and CONUT score (≥3.5) had the worst prognoses. The multivariate Cox proportional hazards analyses suggested that the CONUT score was an independent predictor.The CONUT score was proven to be a significant prognostic factor of clinical outcomes in patients with AMI. However, further research in this area is needed to more fully understand the relationship among nutritional status, inflammation, and cardiovascular diseases, which might help reduce MACEs in patients with AMI.

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.

Astragaloside IV Suppresses High Glucose-Induced NLRP3 Inflammasome Activation by Inhibiting TLR4/NF-κB and CaSR

Long-term exposure to high glucose induces vascular endothelial inflammation that can result in cardiovascular disease. Astragaloside IV (As-IV) is widely used for anti-inflammatory treatment of cardiovascular diseases. However, its mechanism of action is still not fully understood. In this study, we investigated the effect of As-IV on high glucose-induced endothelial inflammation and explored its possible mechanisms. In vivo, As-IV (40 and 80 mg/kg/d) was orally administered to rats for 8 weeks after a single intraperitoneal injection of streptozotocin (STZ, 65 mg/kg). In vitro, human umbilical vein endothelial cells (HUVECs) were treated with high glucose (33 mM glucose) in the presence or absence of As-IV, NPS2143 (CaSR inhibitor), BAY 11-7082 (NF-κB p65 inhibitor), and INF39 (NLRP3 inhibitor), and overexpression of CaSR was induced by infection of CaSR-overexpressing lentiviral vectors to further discuss the anti-inflammatory property of As-IV. The results showed that high glucose increased the expression of interleukin-18 (IL-18), interleukin-1β (IL-1β), NLRP3, caspase-1, and ASC, as well as the protein level of TLR4, nucleus p65, and CaSR. As-IV can reverse these changes in vivo and in vitro. Meanwhile, NPS2143, BAY 11-7082, and INF39 could significantly abolish the high glucose-enhanced NLRP3, ASC, caspase-1, IL-18, and IL-1β expression in vitro. In addition, both NPS2143 and BAY 11-7082 attenuated high glucose-induced upregulation of NLRP3, ASC, caspase-1, IL-18, and IL-1β expression. In conclusion, this study suggested that As-IV could inhibit high glucose-induced NLRP3 inflammasome activation and subsequent secretion of proinflammatory cytokines via inhibiting TLR4/NF-κB signaling pathway and CaSR, which provides new insights into the anti-inflammatory activity of As-IV.

Calcium‑sensing receptors in human peripheral T lymphocytes and AMI: Cause and effect

Acute myocardial infarction (AMI) is a disease associated with inflammation. T lymphocytes are involved by secreting cytokines and inflammatory factors. In our previous study, it was found that the T lymphocytes exhibited certain functional changes, the onset of which was induced by modulating calcium‑sensing receptor (CaSR) in AMI. In the present study, western blotting was used to verified the expression of T lymphocyte CaSR and pathway proteins, including phosphorylated extracellular signal‑regulated kinase (P‑ERK)1/2 and phosphorylated c‑Jun N‑terminal kinase (P‑JNK), and used cytometric bead array to detect the secretion of interleukin (IL)‑4, IL‑6, IL‑10 and tumor necrosis factor (TNF)‑α in AMI onset, the results demonstrated that they were all increased. In addition, the expression of T lymphocyte pathway proteins, including P‑ERK1/2 and P‑JNK, and the secretion of IL‑4, IL‑6, IL‑10 and TNF‑α decreased after T lymphocytes being transfected by CaSR small interfering RNA. By contrast, the neonatal mouse cardiomyocytes under hypoxia and hypoxia/re‑oxygenation exhibited ultrastructural damage, increased apoptosis, increased production of lactate dehydrogenase (LDH) and malondialdehyde, and reduced superoxide dismutase; these indicators changed extensively when cardiomyocytes were co‑cultured with T lymphocytes. However, the effects were reversed when the cardiomyocytes were co‑cultured with CaSR‑silenced T lymphocytes. These results indicated that CaSR may modulate T lymphocytes to release cytokines through mitogen‑activated protein kinase pathways and affect cardiomyocyte injury. The relationship between AMI and T lymphocyte CaSR is reciprocal.

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.

Expression and Role of the Calcium-Sensing Receptor in Rat Peripheral Blood Polymorphonuclear Neutrophils

The calcium-sensing receptors (CaSRs) play an important role in many tissues and organs that are involved in inflammatory reactions. Peripheral blood polymorphonuclear neutrophils (PMNs) are important inflammatory cells. However, the expression and functions of CaSR in peripheral blood PMNs are still not reported. In this study, we collected rat peripheral blood PMNs to observe the relationship between CaSR and PMNs. From the results, we found first that the CaSR protein was expressed in PMNs, and it increased after PMNs were activated with fMLP. In addition, CaSR activator cincalcet promoted the expression of CaSR and P-p65 (NF-κB signaling pathway protein) and Bcl-xl (antiapoptosis protein), and it increased the secretion of interleukin-6 (IL-6) and myeloperoxidase (MPO); meanwhile, it decreased proapoptosis protein Bax expression and the production of IL-10 and reactive oxygen species (ROS). At the same time, cincalcet also decreased the PMN apoptosis rate analyzed by flow cytometry. However, CaSR inhibitor NPS-2143 and NF-κB signaling pathway inhibitor PDTC reverse the results cited earlier. All of these results indicated that CaSR can regulate PMN functions and status to play a role in inflammation, which is probably through the NF-κB signaling pathway.