Dietary γ-Glutamyl Valine Ameliorates TNF-α-Induced Vascular Inflammation via Endothelial Calcium-Sensing Receptors.

γ-Glutamyl valine (γ-EV), commonly found in edible beans, was shown to reduce gastrointestinal inflammation via activation of calcium-sensing receptors (CaSRs). The present study aimed to evaluate the efficacy of γ-EV in modulating the tumor necrosis factor-α-induced inflammatory responses in endothelial cells (ECs) via CaSR-mediated pathways. Human aortic ECs (HAoECs) were pretreated (2 h) with γ-EV (0.01, 0.1, and 1 mM). 1 mM pretreatment of γ-EV significantly reduced the upregulation of inflammatory adhesion molecules, VCAM-1 and E-selectin, by 44.56 and 57.41%, respectively. The production of cytokines IL-8 and IL-6 was significantly reduced by 40 and 51%, respectively, with 1 mM pretreatment of γ-EV. Similarly, there was a significant reduction in chemokine MCP-1 from a positive control of 9.70 ± 0.52 to 6.6 ± 0.43 ng/mL, after γ-EV treatment. The anti-inflammatory effect of γ-EV was attenuated by the treatment of the CaSR-specific inhibitor, NPS-2143, suggesting the involvement of CaSR-mediated pathways. Further studies identified the critical role of key modulators, such as ß-arrestin2 and cyclic adenosine monophosphate response element-binding protein, in mediating the CaSR-dependent anti-inflammatory effect of γ-EV. Finally, the transport efficiency of γ-EV was evaluated through a monolayer of intestinal epithelial cells (Caco-2), and the apparent permeability (Papp) of the peptide was found to be 1.56 × 10-6 cm/s.

Calcium-sensing receptor autoantibody-mediated hypoparathyroidism associated with immune checkpoint inhibitor therapy: diagnosis and long-term follow-up.

BACKGROUND: Immune checkpoint inhibitors (ICIs) have produced significant survival benefit across many tumor types. However, immune-related adverse events are common including autoimmune responses against different endocrine organs. Here, a case of ICI-mediated hypoparathyroidism focusing on long-term follow-up and insights into its etiology is presented. CASE AND METHODS: A 73-year-old man developed severe symptomatic hypocalcemia after the initiation of ipilimumab and nivolumab for the treatment of metastatic melanoma. Hypoparathyroidism was diagnosed with undetectable intact parathyroid hormone (PTH). Immunoprecipitation assays, ELISAs, and cell-based functional assays were used to test the patient for antibodies against the calcium-sensing receptor (CaSR). NACHT leucine-rich repeat protein 5 (NALP5) and cytokine antibodies were measured in radioligand binding assays and ELISAs, respectively. RESULTS: The patient's symptoms improved with aggressive calcium and vitamin D supplementation. At 3 years and 3 months since the diagnosis of hypoparathyroidism, PTH was still inappropriately low at 7.6 pg/mL, and attempted discontinuation of calcium and calcitriol resulted in recurrent symptomatic hypocalcemia. Analysis for an autoimmune etiology of the patient's hypoparathyroidism indicated that CaSR antibodies were negative before treatment and detected at multiple time points afterwards, and corresponded to the patient's clinical course of hypoparathyroidism. CaSR antibodies purified from the patient's serum activated the human CaSR. The patient was seronegative for NALP5 and cytokine antibodies, indicating that their hypoparathyroidism was not a manifestation of autoimmune polyendocrine syndrome type 1. CONCLUSION: The etiology of hypocalcemia is likely autoimmune hypoparathyroidism caused by the development of CaSR-activating antibodies that might prevent PTH release from the parathyroid.

Autoimmune Hypercalcemia Due to Autoantibodies Against the Calcium-sensing Receptor.

CONTEXT: Autoimmune hypocalciuric hypercalcemia (AHH) is an acquired disorder caused by the presence of blocking autoantibodies against the calcium-sensing receptor (CaSR). Few cases of this condition have been described to date in the literature. OBJECTIVE: The objectives of this study were to describe 2 patients in whom the presence of AHH was suspected and to assess the patients for the presence of CaSR antibodies. METHODS: CaSR antibodies were detected and characterised by immunoprecipitation assays, CaSR peptide ELISAs, and functional assays based on the calcium-stimulated accumulation of inositol-1-phosphate in a mammalian cell line expressing the CaSR. RESULTS: Both patients presented with an acquired form of hypocalciuric hypercalcemia. Mutational analyses of CASR, GNA11, and AP2S1 for familial hypocalciuric hypercalcemia were negative. According to the presence of Hashimoto's disease in 1 patient and latent autoimmune diabetes of adulthood and thyroid autoimmunity in the other, AHH was suspected. Immunoprecipitation assays detected CaSR antibodies in both patients. Analysis of the antibody binding sites revealed 2 main epitopes at amino acids 41-69 and 114-126. Preincubation with purified CaSR antibodies against epitope 114-126 resulted in a significant decrease in inositol-1-phophate accumulation upon calcium-stimulation of mammalian cells expressing the CaSR, suggesting that the antibodies had receptor-blocking activity. CONCLUSIONS: AHH is to be suspected in patients with an acquired biochemical pattern of PTH-dependant hypocalciuric hypercalcemia, especially in those with other concomitant autoimmune diseases. Diagnosis by means of detecting CaSR antibodies may help to better characterise this probably under-reported condition.

Calcium-Sensing Receptor on Neutrophil Promotes Myocardial Apoptosis and Fibrosis After Acute Myocardial Infarction via NLRP3 Inflammasome Activation.

BACKGROUND: The infiltration of neutrophils aggravates inflammatory response in acute myocardial infarction (AMI), and the role of calcium-sensing receptor (CaSR) in neutrophil-associated inflammation is largely unknown. The aim of this study was to evaluate the regulatory effects of CaSR on nucleotide-binding oligomerization domain-like receptor pyrin domain-containing 3 (NLRP3) inflammasome in neutrophils and to explore its role in AMI-related ventricular remodelling. METHODS: The expression of CaSR, NLRP3 inflammasome, and interleukin 1ß (IL-1ß) in peripheral blood and infiltrating neutrophils in patients and rats with AMI was detected by western blotting and immunofluorescence. Cardiomyocyte apoptosis was detected by western blotting and transmission electron microscopy. The degree of fibrosis was evaluated by Masson staining and western blotting. RESULTS: We found upregulation of CaSR, NLRP3 inflammasome, Caspase-1, and IL-1ß in peripheral neutrophils from patients with AMI compared with matched healthy controls, peaking on day 1 and decreasing gradually till 7 days. Peripheral and infiltrating neutrophils from rats with AMI showed the same trend. Calindol enhanced NLRP3 inflammasome activation and IL-1ß release in neutrophils from healthy volunteers, which was blocked by inhibitors of the PLC-IP3 pathway and ER-Ca2+ release. Calhex-231 decreased NLRP3 inflammasome activation and IL-1ß release in neutrophils from patients with AMI. The calindol-stimulated neutrophils from healthy rats promoted cardiomyocyte apoptosis and fibrosis of cardiac fibroblasts from healthy rats, which were inhibited by calhex-231. CONCLUSION: The results suggest that CaSR activates NLRP3 inflammasome in neutrophils, contributing to ventricular remodelling after AMI. CaSR inhibition may be a potential therapeutic target for heart failure in AMI.

Activating Antibodies to The Calcium-sensing Receptor in Immunotherapy-induced Hypoparathyroidism.

CONTEXT: Immune checkpoint inhibitors (ICIs), such as programmed cell death protein-1 (PD-1), programmed cell death protein-ligand 1 (PD-L1), and cytotoxic T lymphocyte antigen-4 (CTLA-4) monoclonal antibodies, are approved for the treatment of some types of advanced cancer. Their main treatment-related side-effects are immune-related adverse events (irAEs), especially thyroid dysfunction and hypophysitis. Hypoparathyroidism, on the contrary, is an extremely rare irAE. OBJECTIVES: The aim of the study was to investigate the etiology of autoimmune hypoparathyroidism in a lung cancer patient treated with pembrolizumab, an anti-PD-1. METHODS: Calcium-sensing receptor (CaSR) autoantibodies, their functional activity, immunoglobulin (Ig) subclasses and epitopes involved in the pathogenesis of autoimmune hypoparathyroidism were tested. RESULTS: The patient developed hypocalcemia after 15 cycles of pembrolizumab. Calcium levels normalized with oral calcium carbonate and calcitriol and no remission of hypocalcemia was demonstrated during a 9-month follow-up. The patient was found to be positive for CaSR-stimulating antibodies, of IgG1 and IgG3 subclasses, that were able to recognize functional epitopes on the receptor, thus causing hypocalcemia. CONCLUSION: The finding confirms that ICI therapy can trigger, among other endocrinopathies, hypoparathyroidism, which can be caused by pathogenic autoantibodies.

γ-Glutamylvaline Prevents Low-Grade Chronic Inflammation via Activation of a Calcium-Sensing Receptor Pathway in 3T3-L1Mouse Adipocytes.

The calcium-sensing receptor (CaSR), a G-protein receptor, is well recognized for its role in the regulation of adipocyte proliferation, in modulating adipose tissue dysfunction, and as a potential target for therapeutic intervention. In the present study, we investigate the anti-inflammatory effect of γ-glutamylvaline (γ-EV) on mouse adipocytes and explore the role of γ-EV-activated CaSR in the regulation of cellular homeostasis using the mouse 3T3-L1 cell line in vitro model. Our results indicate that the 3T3-L1 adipocyte-like cells accumulated lipids and expressed CaSR after 2 days of differentiation and 7 days of maturation period. The pretreatment with γ-EV (10 µM) suppressed the production of TNF-α-induced pro-inflammatory cytokines, i.e., IL-6 (23.92 ± 5.45 ng/mL, p < 0.05)) and MCP-1 (101.17 ± 39.93 ng/mL, p < 0.05), while enhancing the expression of PPARγ (1.249 ± 0.109, p < 0.001) and adiponectin (7.37 ± 0.59 ng/mL, p < 0.05). Elevated expression of Wnt5a was detected in γ-EV-treated cells (115.90 ± 45.50, p < 0.001), suggesting the involvement of the Wnt/ß-catenin pathway. Also, phosphorylation of ß-catenin was shown to be significantly inhibited (0.442 ± 0.034) by TNF-α but restored when cells were pretreated with γ-EV (0.765 ± 0.048, p < 0.05). These findings suggest that γ-EV-induced CaSR activation not only prevents TNF-α-induced inflammation in adipocytes but also modulates the cross-talk between Wnt and PPARγ pathways. Concentrations of serine phosphorylated IRS-1 were shown to be lower in γ-EV-treated cells, indicating γ-EV may also prevent inflammation in the context of insulin resistance. Thus, γ-EV-activated CaSR plays a significant role in the cross-talk between adipocyte inflammatory and metabolic pathways through the regulation of extracellular sensing.

Cinacalcet corrects biased allosteric modulation of CaSR by AHH autoantibody.

Biased agonism is a paradigm that may explain the selective activation of a signaling pathway via a GPCR that activates multiple signals. The autoantibody-induced inactivation of the calcium-sensing receptor (CaSR) causes acquired hypocalciuric hypercalcemia (AHH). Here, we describe an instructive case of AHH in which severe hypercalcemia was accompanied by an increased CaSR antibody titer. These autoantibodies operated as biased allosteric modulators of CaSR by targeting its Venus flytrap domain near the Ca2+-binding site. A positive allosteric modulator of CaSR, cinacalcet, which targets its transmembrane domain, overcame this autoantibody effect and successfully corrected the hypercalcemia in this patient. Hence, this is the first study to our knowledge that identifies the interaction site of a disease-causing GPCR autoantibody working as its biased allosteric modulator and demonstrates that cinacalcet can correct the AHH autoantibody effects both in vitro and in our AHH patient. Our observations provide potentially new insights into how biased agonism works and how to design a biased allosteric modulator of a GPCR. Our observations also indicate that the diagnosis of AHH is important because the severity of hypercalcemia may become fatal if the autoantibody titer increases. Calcimimetics may serve as good treatment options for some patients with severe AHH.

Immunosuppressive therapy of autoimmune hypoparathyroidism in a patient with activating autoantibodies against the calcium-sensing receptor.

CONTEXT: Activating antibodies directed at the extracellular calcium-sensing receptor (CaSR) have been described in autoimmune hypoparathyroidism in the setting of isolated hypoparathyroidism or autoimmune polyglandular syndrome type 1. MATERIALS AND METHODS: A 34-year-old female presented with hypocalcaemia (6.0 mg/dL) and hypomagnesaemia (1.1 mg/dL) accompanied by low serum PTH (2.4 pg/mL) as well as urinary calcium and magnesium wasting. She was diagnosed with hypoparathyroidism, which was refractory to standard therapy. She was started on 60 mg prednisone and 150 mg azathioprine treatment daily on suspicion of an autoimmune aetiology. The patient was tested for CaSR antibodies. RESULTS: The patient was positive for CaSR antibodies of the IgG1 subtype, which stimulated phosphorylation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) and inositol phosphate (IP) accumulation. Post-treatment with prednisone and azathioprine, her serum calcium and magnesium normalized, as did her CaSR antibody titre and antibody-mediated stimulation of ERK1/2 phosphorylation and IP accumulation. CONCLUSION: This is the first demonstration of CaSR antibody-mediated hypoparathyroidism responsive to immunosuppressive therapy, adding to the evidence that autoimmune hypoparathyroidism can be, in some cases, reversible and not the result of autoimmune parathyroid destruction.

Combining Calcium Phosphates with Polysaccharides: A Bone-Inspired Material Modulating Monocyte/Macrophage Early Inflammatory Response.

The use of inorganic calcium/phosphate supplemented with biopolymers has drawn lots of attention in bone regenerative medicine. While inflammation is required for bone healing, its exacerbation alters tissue regeneration/implants integration. Inspired by bone composition, a friendly automated spray-assisted system was used to build bioactive and osteoinductive calcium phosphate/chitosan/hyaluronic acid substrate (CaP-CHI-HA). Exposing monocytes to CaP-CHI-HA resulted in a secretion of pro-healing VEGF and TGF-ß growth factors, TNF-α, MCP-1, IL-6 and IL-8 pro-inflammatory mediators but also IL-10 anti-inflammatory cytokine along with an inflammatory index below 1.5 (versus 2.5 and 7.5 following CaP and LPS stimulation, respectively). Although CD44 hyaluronic acid receptor seems not to be involved in the inflammatory regulation, results suggest a potential role of chemical composition and calcium release from build-up substrates, in affecting the intracellular expression of a calcium-sensing receptor. Herein, our findings indicate a great potential of CaP-CHI-HA in providing required inflammation-healing balance, favorable for bone healing/regeneration.

Calcium-Sensing Receptor Autoantibodies in Patients with Autoimmune Polyendocrine Syndrome Type 1: Epitopes, Specificity, Functional Affinity, IgG Subclass, and Effects on Receptor Activity.

A major manifestation of autoimmune polyendocrine syndrome type 1 (APS1) is hypoparathyroidism, which is suggested to result from aberrant immune responses against the parathyroid glands. The calcium-sensing receptor (CaSR), which plays a pivotal role in maintaining calcium homeostasis by sensing blood calcium levels and regulating release of parathyroid hormone (PTH), is an autoantibody target in APS1. In this study, the aim was to characterize the binding sites, specificity, functional affinity, IgG subclass, and functional effects of CaSR autoantibodies using phage-display technology, ELISA, and bioassays. The results indicated that CaSR autoantibody binding sites were at aa 41-69, 114-126, 171-195, and 260-340 in the extracellular domain of the receptor. Autoantibodies against CaSR epitopes 41-69, 171-195, and 260-340 were exclusively of the IgG1 subclass. Autoantibody responses against CaSR epitope 114-126 were predominantly of the IgG1 with a minority of the IgG3 subclass. Only autoantibodies recognizing CaSR epitopes 114-126 and 171-195 affected receptor activity; inositol-phosphate accumulation was increased significantly in HEK293-CaSR cells, and PTH secretion from PTH-C1 cells was reduced significantly when either were incubated with purified Ab and Ca2+ compared with Ca2+ alone. In conclusion, although the majority of APS1 patients do not have CaSR-stimulating autoantibodies, the hypoparathyroid state in a small minority of patients is the result of functional suppression of the parathyroid glands.

Role of calcium-sensing receptor, Galectin-3, Cyclin D1, and Ki-67 immunohistochemistry to favor in the diagnosis of parathyroid carcinoma.

BACKGROUND: As histopathological findings of parathyroid carcinoma are not certain, the diagnosis of tumors with degenerative changes may be difficult. In these cases, immunohistochemical markers are beneficial. We aimed to research the acceptability of calcium-sensing receptor (CaSR), Galactin-3, Cyclin D1, and Ki-67 as helpful markers in parathyroid tumors in cases which are difficult to diagnose. MATERIALS AND METHODS: Those cases who had been diagnosed with atypical parathyroid adenoma and parathyroid carcinoma between 2010 and 2015 were reevaluated. Immunohistochemical markers were applied to this cases. RESULTS: About 21 cases were parathyroid adenoma, 14 were atypical adenoma, and 10 cases were parathyroid carcinoma. According to the immunohistochemical results, global loss of CaSR staining was seen in 50% (5/10) of the patients with carcinoma while there was no loss of staining in those with parathyroid adenoma (P = 0,001). Global loss of CaSR staining was found in only one out of 14 cases with atypical adenoma. The expression of Galactin-3 was found to be positive in 40% (4/10) of carcinoma cases, 71.4% (10/14) of those with atypical adenoma, and 14.3% (3/21) of those with adenoma (P = 0,002). Cyclin D1 expression was determined to be positive in 70% (7/10) of patients with carcinoma, 71.4% (10/14) of atypical adenoma cases, and 23.8% (5/21) of those with adenoma. The Ki-67 proliferation index was seen to be above 5% in 50% (5/10) of carcinoma cases and 35,7% (5/14) of those with atypical adenoma. CONCLUSION: In these studies, it has been emphasized that the global loss of CaSR staining was used as a negative marker in the diagnosis of carcinoma. In this study, we have also confirmed that the global loss of CaSR staining is a useful marker to determine potential increased malignancy.

Autoantibodies against the calcium-sensing receptor and cytokines in autoimmune polyglandular syndromes types 2, 3 and 4.

OBJECTIVE: The frequency of autoimmunity against the parathyroid glands in patients with polyglandular autoimmunity that is not due to autoimmune polyendocrine syndrome type 1 (APS1) is unclear. To investigate this, this study aimed to determine the prevalence of autoantibodies against parathyroid autoantigens, calcium-sensing receptor (CaSR) and NACHT leucine-rich-repeat protein 5 (NALP5), in a large group of patients with non-APS1 polyendocrine autoimmunity. Possible occult APS1 was investigated by cytokine autoantibody measurement and AIRE gene analysis. DESIGN, SUBJECTS AND MEASUREMENTS: Subjects were 178 patients with APS2, 3 or 4, and 80 healthy blood donors. Autoantibodies against the CaSR, NALP5 and cytokines were measured by immunoprecipitation, radioligand binding assays or ELISA, respectively. RESULTS: Four patient samples (2.2%), but none of the controls, were positive for CaSR autoantibodies. NALP5 autoantibodies were not detected in any participant. Eleven patients (6.2%) had cytokine autoantibodies, but none of the control samples was positive. None of the patients with cytokine autoantibodies had any known or novel mutations in the AIRE gene. CONCLUSIONS: The low prevalence of CaSR autoantibodies indicate a very low level of subclinical parathyroid autoimmunity in APS types 2, 3 and 4. In addition, autoantibodies against cytokines constitute an uncommon feature of non-APS1 polyglandular autoimmunity.

Glucocorticoid-responsive lymphocytic parathyroiditis and hypocalciuric hypercalcemia due to autoantibodies against the calcium-sensing receptor: a case report and literature review.

OBJECTIVE: Autoimmune lymphocytic parathyroiditis and acquired hypocalciuric hypercalcemia associated with autoantibodies against the calcium-sensing receptor (anti-CaSR) are rare and poorly understood conditions. Here, we describe a patient with acquired parathyroid hormone (PTH)-dependent hypercalcemia with associated hypocalciuria, found to have true lymphocytic parathyroiditis on histopathology, and circulating anti-CaSR antibodies in serum. DESIGN AND METHODS: A 64-year-old woman was referred to our clinic for persistent hypercalcemia after a subtotal parathyroidectomy. She was normocalcemic until the age of 63 years when she was diagnosed with primary hyperparathyroidism. She underwent subtotal parathyroidectomy with appropriate intraoperative PTH decline. Two weeks post-parathyroidectomy, she presented with persistent hypercalcemia and hyperparathyroidism. Urine studies revealed an inappropriately low 24-h urine calcium (Ca)/creatinine clearance ratio. Surgical pathology was consistent with true lymphocytic parathyroiditis with lymphoid follicles. The presence of circulating anti-CaSR antibodies was detected by immunoprecipitation of CaSR by the patient's serum. After a 4-week course of prednisone, serum Ca and PTH normalized, and her anti-CaSR titers declined. She remains normocalcemic 10 months after the discontinuation of glucocorticoid therapy. We present this patient in the context of the relevant published literature on lymphocytic parathyroiditis and acquired hypocalciuric hypercalcemia related to anti-CaSR antibodies. CONCLUSIONS: Autoimmune lymphocytic parathyroiditis and acquired hypocalciuric hypercalcemia associated with anti-CaSR antibodies is a very rare yet important condition to be considered in a patient with acquired PTH-dependent hypercalcemia with inappropriate hypocalciuria. Although subtotal parathyroidectomy is unlikely to correct the hypercalcemia, this entity may respond to a short course of prednisone therapy.

Presence of Autoreactive, MHC Class I-Restricted, Calcium-Sensing Receptor (CaSR)-Specific CD8+ T Cells in Idiopathic Hypoparathyroidism.

Context: Major histocompatibility complex class I allele HLA-A*26:01 and human leukocyte antigen (HLA) supertype A01 (STA01) are increased in idiopathic hypoparathyroidism (IH). However, cell-mediated autoimmune responses directed against the calcium-sensing receptor (CaSR) have not been demonstrated. Objective: To study CaSR-specific cytotoxic T-cell responses in peripheral blood mononuclear cells of IH patients. Design: Twenty-four peptides of CaSR (RH1 to RH24) were evaluated for their ex vivo potential to stimulate PBMCs from IH patients and controls in interferon (IFN)-γ enzyme-linked immunospot (ELISPOT) assays. Setting: Tertiary patient care center and National Institute of Immunology, New Delhi, India. Patients and Other Participants: Forty-five patients with IH attending the endocrine clinic of the All India Institute of Medical Sciences and 22 healthy controls. Main Outcome Measures: Major histocompatibility complex class-I restricted, CaSR-specific cytotoxic CD8+ T-cell responses evaluated by IFN-γ ELISPOT assay. Results: Of IH patients, 82.2% showed IFN-γ-secreting cells when stimulated ex-vivo with CaSR peptides. Peptides RH7, RH9, and RH16 elicited HLA supertype A01-restricted responses in IH. RH8, RH14, RH15, RH20, and RH21 peptides induced significantly higher responses in STA01+ IH patients compared with healthy controls irrespective of their supertype A01 status. Conclusions: Our ex vivo IFN-γ ELISPOT assays demonstrate the presence of CaSR-specific memory CD8+ T cells in the peripheral circulation of patients with IH, suggesting the role of cell-mediated autoimmune responses in the etiopathogenesis of IH.

Chitosan Oligosaccharide Reduces Intestinal Inflammation That Involves Calcium-Sensing Receptor (CaSR) Activation in Lipopolysaccharide (LPS)-Challenged Piglets.

Chitosan oligosaccharide (COS) is a degradation product of chitosan with antioxidative, anti-inflammatory, and antibacterial effects. This study was conducted to investigate the effects of dietary COS on the intestinal inflammatory response and the calcium-sensing receptor (CaSR) and nuclear transcription factor kappa B (NF-κB) signaling pathways that may be involved using a lipopolysaccharide (LPS)-challenged piglet model. A total of 40 weaned piglets were used in a 2 × 2 factorial design; the main factors were dietary treatment (basal or 300 µg/kg COS) and inflammatory challenge (LPS or saline). On the morning of days 14 and 21 after the initiation of treatment, the piglets were injected intraperitoneally with Escherichia coli LPS at 60 and 80 µg/kg body weight or the same amount of sterilized saline, respectively. Blood and small intestine samples were collected on day 14 or 21, respectively. The results showed that piglets challenged with LPS have a significant decrease in average daily gain and gain:feed and histopathological injury in the jejunum and ileum, whereas dietary supplementation with COS significantly alleviated intestinal injury induced by LPS. Piglets fed the COS diet had lower serum concentrations of tumor necrosis factor alpha (TNF-α), interleukin (IL) 6, and IL-8 as well as lower intestinal abundances of pro-inflammatory cytokine mRNA but higher anti-inflammatory cytokine mRNA compared with piglets fed the basal diet among LPS-challenged piglets (p < 0.05). Dietary COS increased intestinal CaSR and PLCß2 protein expressions in both saline- and LPS-treated piglets, but decreased p-NF-κB p65, IKKα/ß, and IκB protein expressions in LPS-challenged piglets (p < 0.05). These findings indicate that COS has the potential to reduce the intestinal inflammatory response, which is concomitant with the activation of CaSR and the inhibition of NF-κB signaling pathways under an inflammatory stimulus.

Anti-inflammatory Effects of Poly-L-lysine in Intestinal Mucosal System Mediated by Calcium-Sensing Receptor Activation.

Calcium-sensing receptor (CaSR) is involved in maintaining cellular homeostasis and promoting recovery of damaged intestinal epithelial cells (IECs). Poly-L-lysine (PL) is a basic polypeptide identified for its role in the activation of CaSR through allosteric binding. The primary goal of the current study was to identify the modulatory effect of PL on intestinal inflammation and to determine whether these effects were mediated by CaSR activation. We used human intestinal epithelial cell lines, Caco-2 and HT-29, to assess PL anti-inflammatory activities in vitro. We found that PL reduced the IL-8 secretion from tumor necrosis factor (TNF)-α-treated human intestinal epithelial cell lines. On the other hand, the gene expression of pro-inflammatory cytokines TNF-α, IL-6, and IL-1ß was inhibited by PL supplementation. We subsequently evaluated the anti-inflammatory activity of PL in vivo using a DSS-induced mouse colitis model. PL supplementation was shown to prevent dextran sulfate sodium salt (DSS)-induced loss of weight, colitic symptoms, and shortening of colon length but maintained colonic morphology. The pro-inflammatory cytokine expression in the mouse colon, including TNF-α, IL-6, INF-γ, IL-17, and IL-1ß, was significantly up-regulated by DSS treatment, but was inhibited upon PL administration. As shown by the results from both in vitro and in vivo studies, the reduction of inflammatory cytokine production caused by PL was reversed by NPS-2143 pretreatment. In the present study, we provide evidence that PL exerts anti-inflammatory effects on the gut system, which is primarily mediated by allosteric ligand activation of CaSR.

Calcium-sensing receptor (CaSR)-mediated anti-inflammatory effects of L-amino acids in intestinal epithelial cells.

Calcium-sensing receptor (CaSR) plays an essential role in sensing nutrients and monitoring ion balance in the human gut. However, no discovery of CaSR-mediated anti-inflammatory effect of l-amino acids (l-AAs) on the gut system has been reported. The aim of this study is to screen and identify the anti-inflammatory activity of various l-AAs in intestinal epithelial cells (IECs) and stepwise illustrate a possible molecular mechanism for anti-inflammation. We used Caco-2 and HT-29 cell lines to evaluate the anti-inflammatory activity of l-AAs and revealed that l-tryptophan (l-Trp) and l-valine (l-Val) have strong anti-inflammatory activity consistent in both cell lines. l-Trp treatment (5 mM) reduced TNF-α-induced IL-8 secretion from HT-29 or Caco-2 cells to about 50 or 40%, respectively. l-Trp also significantly inhibited the expression of phosphorylation of JNK or IκBα to around 50% in HT-29 cells. However, the above inhibitory effects of l-Trp on inflammatory responses in TNF-α-induced HT-29 cells were abrogated by NPS-2143. The result of CaSR antagonist NPS-2143 pretreatment study suggests l-Trp exerts anti-inflammatory effects on IECs through CaSR activation. The involvement of ß-arrestin2 was then found to block tumor necrosis factor (TNF)-α-induced signaling pathways after CaSR activated by l-Trp. These results validate a novel mechanism underlying CaSR agonistic l-AAs exerting anti-inflammatory effects on human intestinal epithelia.

[Chronic hypocalcemia due to anti-calcium sensing receptor antibodies]. / Hipocalcemia crónica por anticorpos anti-recetor do cálcio.

INTRODUCTION: Hypoparathyroidism is an entity associated with hypocalcemia, more frequently a consequence of neck surgery. An autoimmune etiology is rare and its diagnosis difficult to establish. CLINICAL REPORT: 52 year-old woman, with irrelevant past medical history and no significant familial conditions, referred because of hypocalcemia and basal ganglia calcifications, detected in the course of investigation of myalgias. Besides hypocalcemia (4.6 mg/ dL), hyperphosphatemia (8.7 mg/dL), undetectable parathyroid hormone and low urinary calcium, phosphorus and magnesium were present. Molecular analysis of CaSR gene excluded germinal mutations. Anti-calcium sensing receptor antibodies (anti-CaSR) were present. The patient is asymptomatic and normocalcemic under treatment with calcium and vitamin D. DISCUSSION: Although rare, hypocalcemia due to anti-CaSR hypoparathyroidism must be considered in the absence of previous neck surgery, hypocalcemic drugs, familial history or phenotype suggesting a genetic disorder. Low or undetectable parathyroid hormone excludes pseudohypoparathyroidism and anti-CaSR positivity establishes the diagnosis.

Introdução: O hipoparatiroidismo cursa com hipocalcemia e é mais frequentemente registado após cirurgia cervical. A etiologia autoimune é mais rara e difícil de diagnosticar. Caso clínico: Mulher, 52 anos, sem antecedentes pessoais, medicamentosos ou familiares relevantes, referenciada por hipocalcemia e calcificação dos núcleos da base, detetados no decurso de investigação de quadro de mialgias. Além de hipocalcemia (4,6 mg/dL), foi verificada hiperfosfatemia (8,7 mg/dL), hormona paratiroideia indetetável, calciúria, fosfatúria e magnesúria baixas. A análise molecular do gene CaSR excluiu mutações germinais. A pesquisa de anticorpos anti-receptor sensível do cálcio (anti-CaSR) foi positiva. Atualmente está assintomática e normocalcémica sob terapêutica com cálcio e vitamina D. Discussão: Embora rara, a hipocalcemia por hipoparatiroidismo autoimune deve ponderar-se em adultos sem antecedentes de cirurgia cervical, medicação hipocalcemiante, história familiar ou fenótipo sugestivo de doença genética. Hormona paratiroideia diminuída ou indetetável exclui pseudohipoparatiroidismo e a positividade para anti-CaSR confirma o diagnóstico.