Involvement of soluble adhesion molecules in acute pancreatitis

Immune markers of severe acute pancreatitis

PURPOSE OF REVIEW

Acute pancreatitis is a common acute inflammatory disorder of the pancreas, and its incidence has been increasing worldwide. Approximately 10% of acute pancreatitis progresses to severe acute pancreatitis (SAP), which carries significant morbidity and mortality. Disordered immune response to pancreatic injury is regarded as a key event that mediates systemic injury in SAP. In this article, we review recent developments in immune biomarkers of SAP and future directions for research.

RECENT FINDINGS

Given the importance of the NLRP3-inflammasome pathway in mediating systemic inflammatory response syndrome and systemic injury, recent studies have investigated associations of SAP with systemic levels of activators of NLRP3, such as the damage associated molecular patterns (DAMPs) for the first time in human SAP. For example, circulating levels of histones, mitochondrial DNAs, and cell free DNAs have been associated with SAP. A panel of mechanistically relevant immune markers (e.g., panel of Angiopoeitin-2, hepatocyte growth factor, interleukin-8 (IL-8), resistin and sTNF-α R1) carried higher predictive accuracies than existing clinical scores and individual immune markers. Of the cytokines with established relevance to SAP pathogenesis, phase 2 trials of immunotherapies, including tumor necrosis factor (TNF)-alpha inhibition and stimulation of IL-10 production, are underway to determine if altering the immunologic response can reduce the severity of acute pancreatitis (AP).

SUMMARY

Circulating systemic levels of various DAMPs and a panel of immune markers that possibly reflect activities of different pathways that drive SAP appear promising as predictive biomarkers for SAP. But larger multicenter studies are needed for external validation. Studies investigating immune cellular pathways driving SAP using immunophenotyping techniques are scarce. Interdisciplinary efforts are also needed to bring some of the promising biomarkers to the bedside for validation and testing for clinical utility. Studies investigating the role of and characterization of altered gut-lymph and gut-microbiota in severe AP are needed.

Fire in the belly: A scoping review of the immunopathological mechanisms of acute pancreatitis

Introduction

Acute pancreatitis (AP) is characterised by an inflammatory response that in its most severe form can cause a systemic dysregulated immune response and progression to acute multi-organ dysfunction. The pathobiology of the disease is unclear and as a result no targeted, disease-modifying therapies exist. We performed a scoping review of data pertaining to the human immunology of AP to summarise the current field and to identify future research opportunities.

Methods

A scoping review of all clinical studies of AP immunology was performed across multiple databases. Studies were included if they were human studies of AP with an immunological outcome or intervention.

Results

205 studies met the inclusion criteria for the review. Severe AP is characterised by significant immune dysregulation compared to the milder form of the disease. Broadly, this immune dysfunction was categorised into: innate immune responses (including profound release of damage-associated molecular patterns and heightened activity of pattern recognition receptors), cytokine profile dysregulation (particularly IL-1, 6, 10 and TNF-α), lymphocyte abnormalities, paradoxical immunosuppression (including HLA-DR suppression and increased co-inhibitory molecule expression), and failure of the intestinal barrier function. Studies including interventions were also included. Several limitations in the existing literature have been identified; consolidation and consistency across studies is required if progress is to be made in our understanding of this disease.

Conclusions

AP, particularly the more severe spectrum of the disease, is characterised by a multifaceted immune response that drives tissue injury and contributes to the associated morbidity and mortality. Significant work is required to develop our understanding of the immunopathology of this disease if disease-modifying therapies are to be established.

Role of Hydrogen Sulfide, Substance P and Adhesion Molecules in Acute Pancreatitis

Inflammation is a natural response to tissue injury. Uncontrolled inflammatory response leads to inflammatory disease. Acute pancreatitis is one of the main reasons for hospitalization amongst gastrointestinal disorders worldwide. It has been demonstrated that endogenous hydrogen sulfide (H₂S), a gasotransmitter and substance P, a neuropeptide, are involved in the inflammatory process in acute pancreatitis. Cell adhesion molecules (CAM) are key players in inflammatory disease. Immunoglobulin (Ig) gene superfamily, selectins, and integrins are involved at different steps of leukocyte migration from blood to the site of injury. When the endothelial cells get activated, the CAMs are upregulated which leads to them interacting with leukocytes. This review summarizes our current understanding of the roles H₂S, substance P and adhesion molecules play in acute pancreatitis.

Adhesion molecules and pancreatitis

Acute and chronic pancreatitises are gastrointestinal inflammatory diseases, the incidence of which is increasing worldwide. Most (~ 80%) acute pancreatitis (AP) patients have mild disease, and about 20% have severe disease, which causes multiple organ failure and has a high mortality rate. Chronic pancreatitis (CP) is characterized by chronic inflammation and destruction of normal pancreatic parenchyma, which leads to loss of exocrine and endocrine tissues. Patients with CP also have a higher incidence of pancreatic ductal adenocarcinoma. Although a number of factors are associated with the development and progression of AP and CP, the underlying mechanism is unclear. Adhesion molecules play important roles in cell migration, proliferation, and signal transduction, as well as in development and tissue repair. Loosening of cell-cell adhesion between pancreatic acinar cells and/or endothelial cells increases solute permeability, resulting in interstitial edema, which promotes inflammatory cell migration and disrupts tissue structure. Oxidative stress, which is one of the important pathogenesis of pancreatitis, leads to upregulation of adhesion molecules. Soluble adhesion molecules are reportedly involved in AP. In this review, we focus on the roles of tight junctions (occludin, tricellulin, claudin, junctional adhesion molecule, and zonula occludin), adherens junctions (E-cadherin and p120-, α-, and β-catenin), and other adhesion molecules (selectin and intercellular adhesion molecules) in the progression of AP and CP. Maintaining the normal function of adhesion molecules and preventing their abnormal activation maintain the structure of the pancreas and prevent the development of pancreatitis.

The profiles of soluble adhesion molecules in the "great obstetrical syndromes". J Matern Fetal Neonatal Med 2018;32:2113-2136. [PMID: 29320948 DOI: 10.1080/14767058.2018.1427058]

OBJECTIVE

The objective of this study was to determine the profiles of maternal plasma soluble adhesion molecules in patients with preeclampsia, small-for-gestational-age (SGA) fetuses, acute pyelonephritis, preterm labor with intact membranes (PTL), preterm prelabor rupture of the membranes (preterm PROM), and fetal death.

MATERIALS AND METHODS

A cross-sectional study was conducted to determine maternal plasma concentrations of sE-selectin, sL-selectin, and sP-selectin as well as sICAM-1, sVCAM-1, and sPECAM-1 in patients with (1) an uncomplicated pregnancy (control, n = 100); (2) preeclampsia (n = 94); (3) SGA fetuses (in women without preeclampsia/hypertension, n = 45); (4) acute pyelonephritis (n = 25); (5) PTL (n = 53); (6) preterm PROM (n = 24); and (7) fetal death (n = 34). Concentrations of soluble adhesion molecules and inflammatory cytokines (tumor necrosis factor (TNF)-α and interleukin (IL)-8) were determined with sensitive and specific enzyme-linked immunoassays.

RESULTS

In comparison to women with a normal pregnancy, (1) women with preeclampsia had higher median concentrations of sE-selectin, sP-selectin, and sVCAM-1, and a lower concentration of sL-selectin (all p values < .001); (2) patients with SGA fetuses had higher median concentrations of sE-selectin, sP-selectin, and sVCAM-1 (all p values < .05); (3) patients with a fetal death had higher median concentrations of sE-selectin and sP-selectin (all p values < .05); (4) patients with acute pyelonephritis had higher median plasma concentrations of sE-selectin, sICAM-1, and sVCAM-1 (all p values < .001); (5) patients with preeclampsia and acute pyelonephritis, plasma concentrations of sVCAM-1, sE-selectin, and sP-selectin correlated with those of the proinflammatory cytokines TNF-α and interleukin (IL)-8 (all p values < .05); (6) patients with PTL had a higher median concentration of sP-selectin and a lower median concentration of VCAM-1 (all p values < .05); and (7) women with preterm PROM had lower median concentrations of sL-selectin and sVCAM-1 (all p values < .05).

CONCLUSIONS

The results of this study show that endothelial cell activation/dysfunction reflected by the plasma concentration of sE-selectin is not specific to preeclampsia but is present in pregnancies complicated by SGA fetuses, acute pyelonephritis, and fetal death. Collectively, we report that each obstetrical syndrome appears to have a stereotypical profile of soluble adhesion molecules in the peripheral circulation.

The Interplay between Inflammation, Coagulation and Endothelial Injury in the Early Phase of Acute Pancreatitis: Clinical Implications

Acute pancreatitis (AP) is an inflammatory disease with varied severity, ranging from mild local inflammation to severe systemic involvement resulting in substantial mortality. Early pathologic events in AP, both local and systemic, are associated with vascular derangements, including endothelial activation and injury, dysregulation of vasomotor tone, increased vascular permeability, increased leukocyte migration to tissues, and activation of coagulation. The purpose of the review was to summarize current evidence regarding the interplay between inflammation, coagulation and endothelial dysfunction in the early phase of AP. Practical aspects were emphasized: (1) we summarized available data on diagnostic usefulness of the markers of endothelial dysfunction and activated coagulation in early prediction of severe AP; (2) we reviewed in detail the results of experimental studies and clinical trials targeting coagulation-inflammation interactions in severe AP. Among laboratory tests, d-dimer and angiopoietin-2 measurements seem the most useful in early prediction of severe AP. Although most clinical trials evaluating anticoagulants in treatment of severe AP did not show benefits, they also did not show significantly increased bleeding risk. Promising results of human trials were published for low molecular weight heparin treatment. Several anticoagulants that proved beneficial in animal experiments are thus worth testing in patients.

Effects of thymosin β4 on a rat model of severe acute pancreatitis

The aim of the present study was to investigate the effects of thymosin β4 on a rat model of severe acute pancreatitis (SAP) induced by sodium taurocholate (STC) and the underlying mechanism. SAP was induced by the retrograde infusion of 5% STC (1 ml/kg) into the bile-pancreatic duct. In certain rats, thymosin β4 (30 mg/kg) was administered intraperitoneally 30 min prior to the infusion of STC. The severity of pancreatitis was evaluated by the measurement of serum amylase, lipase, tumor necrosis factor-α, interleukin (IL)-1β, IL-6 and myeloperoxidase (MPO) levels, and histological grading. Nuclear factor (NF)-κB activation was evaluated by immunohistochemistry and western blot analysis. Intercellular adhesion molecule (ICAM)-1 protein expression in the pancreas was studied using western blot analysis. Prophylactic administration of thymosin β4 was found to attenuate serum amylase and lipase activity and the serum concentrations of proinflammatory cytokines. In addition, it attenuated pathological pancreatic injury, pancreatic MPO activity, and the activation of NF-κB and ICAM-1 in the pancreas. These results suggest that thymosin β4 exerts a protective effect against STC-induced pancreatic injury.

Circulating endothelial mediators in human pancreatitis-associated lung injury

OBJECTIVES

To investigate the role of endothelial cell mediators, E-selectin (ES), intercellular adhesion molecule-1 (ICAM-1), tissue factor (TF), and von Willebrand factor (vWF), in the early phase of severe acute pancreatitis (SAP) complicated with respiratory failure [pancreatitis-associated lung injury (PALI)].

PATIENTS AND METHODS

This study included 30 patients with SAP and 39 patients with PALI. Blood samples were taken from SAP and PALI patients on presenting to the hospital (day 1), and days 2, 3, 5, and 10. The relationship between blood concentrations of the studied endothelial mediators and lung function tests was analyzed.

RESULTS

PALI patients had significantly higher ES, ICAM-1, TF, and vWF blood levels than those with SAP as early as at admission and throughout the period studied. We found the highest concentration of ES on the second day, ICAM-1 and TF at admission, and vWF level on the fifth day. There were adverse correlations between ES, ICAM-1, TF, vWF concentrations, and the index of oxygenation--PaO2/FiO2 ratio (Rs=-0.385, Rs=-0.523, Rs=-0.505, Rs=-0.408, P<0.001, respectively). The most accurate prediction of PALI was provided by ICAM-1 and TF levels on the day of admission [areas under curve (AUCs): ES, 0.704; ICAM-1, 0.787; TF, 0.757; and vWF, 0.686].

CONCLUSION

Endothelium-related mediators ES, ICAM-1, TF, and vWF appear to participate in pancreatitis-associated lung injury. In SAP, the measurement of endothelial mediator levels (especially ICAM-1 and TF) may be used as an early prognostic indicator that would predict the development of respiratory failure and to monitor the severity of lung dysfunction.

Changes of serum adhesion molecules and cytokines in post-ERCP pancreatitis: adhesion molecules and cytokines in acute pancreatitis

OBJECTIVES

To assess the early changes of soluble IFN-γ, IL-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12, TNF-α, TNF-β, IL-17A, IL-22, soluble (s) P-Selectin, sE-Selectin and sICAM-1 in post-ERCP pancreatitis (PEP).

METHODS

Single center, prospective study of 318 ERCP procedures. Serum samples were acquired from all patients prior to ERCP, 6 hours and 24 hours after the procedure. For every PEP case, another patient was chosen as a control, matched for gender, age and time period in which ERCP took place.

RESULTS

Totally, 28 cases and 28 controls were studied. Except for significantly higher IL-1b levels in cases at baseline, no significant differences were observed between cases and controls after Bonferroni corrections. An increase in IL-6 was noted between baseline and 6 h in cases alone (p=0.016). There was a significant fall in sP-selectin levels at 6 and 24 hours compared to baseline in all patients (corrected p=0.008 and 0.016 for cases and 0.016 and 0.048 for controls respectively). An increase of sE-selectin in cases was observed between 6 and 24 hours post-ERCP (corrected p=0.03).

CONCLUSIONS

Soluble forms of cytokines and adhesion molecules studied seem not to play a major role in PEP.

Serum adhesion molecules in acute pancreatitis: time course and early assessment of disease severity

OBJECTIVES

To evaluate the adhesion molecule time course in the early phases of acute pancreatitis and to explore the usefulness of these proteins in assessing the severity of the disease. Fifteen consecutive acute pancreatitis patients (10 patients with the mild and 5 with the severe disease) admitted to the hospital within 6 hours after the onset of pain and 15 age- and sex-matched healthy subjects.

METHODS

Vascular cell adhesion molecule 1, intercellular adhesion molecule 1, E-selectin, P-selectin, and L-selectin were quantified on hospital admission and for the following 2 days.

RESULTS

Acute pancreatitis patients had vascular cell adhesion molecule 1 and P-selectin concentrations significantly lower and L-selectin concentrations significantly higher than the healthy subjects. Only E-selectin was significantly higher in severe than in mild disease (P = 0.029); a value of E-selectin ranging from 3.83 to 3.92 ng/mL was the best cutoff value for differentiating severe from mild acute pancreatitis (sensitivity: 60.0%, specificity: 90.0%, cases correctly classified: 80%). E-selectin and P-selectin entered the multivariate logistic regression analysis, and a score was calculated showing a sensitivity of 93.3% and a specificity of 86.7% in identifying the patients with severe pancreatitis.

CONCLUSIONS

This score seems to be useful for the early assessment of the severity of acute pancreatitis.

A randomized controlled trial of pentoxifylline for the prevention of post-ERCP pancreatitis

BACKGROUND

Pentoxifylline can ameliorate pancreatitis in animal models because of its anti-tumor necrosis factor properties.

OBJECTIVE

Our purpose was to study the safety and efficacy of pentoxifylline in the prevention of post-ERCP pancreatitis.

DESIGN

Patients due to undergo ERCP for various indications were randomized to receive pentoxifylline 400 mg orally 3 times, beginning the day before ERCP (2 and 10 pm) until the night after the procedure (6 am and 2 and 10 pm) or to receive no preventive medication. Serum amylase values were determined before and 6 and 24 hours after ERCP. Diagnosis and grading of the severity of complications was performed according to consensus criteria.

PATIENTS

One hundred fifty-eight patients received pentoxifylline (group A) and 162 had no medication (group B). The groups were similar in distributions of sex, biliary sphincterotomy, pancreatography, pancreatic duct cannulations, stone extraction, stent placement, and presence of periampullary diverticulum. Group A patients were younger (mean age 63 vs 68 years, P<.05) and biliary colic was a more frequent indication (30 vs 12, P<.05).

RESULTS

Nine (5.6%) patients in group A and 5 (3%) in group B had pancreatitis (2 and 1 severe, respectively; P=.28). Serum amylase values were similar in baseline and 6- and 24-hour samples. Two (1.2%) patients in group A and 7 (4.3%) in group B had hemorrhage.

LIMITATIONS

This was not a double-blind trial.

CONCLUSIONS

In this study pentoxifylline did not protect against post-ERCP pancreatitis or hyperamylasemia.

Mechanism of lung injury and protective effect of prostaglandin E1 in experimental acute pancreatitis

AIM: To explore the mechanism of lung injury in experimental acute pancreatitis (AP) and the protective effect of prostaglandin E₁ (PGE₁).

METHODS: Seventy-eight rats were averagely and randomly divided into sham operation, AP, and PGE₁ group. AP model was induced by creating a closed duod enal loop in rats. The rats in PGE₁ group were intravenously injected with PGE₁ (60 ng/kg). The histopathological changes of pancreatic and pulmonary tissues were examined by microscopy. The serum level of amylase, the activity of myeloperoxidase (MPO), the pulmonary level of lipid peroxidation (LPO), and lung capillary permeability (LCP) were measured. The expression of pulmonary intercellular adhesion molecule-1 (ICAM-1) was determined by immunohistochemical technique (ABC).

RESULTS: In AP group, the progressive pathological damages in the pancreas and lung tissues were clearly observed. The activity of pulmonary MPO (12 h: 5.65 ± 0.80 vs 1.22 ± 0.71 kat/g, P < 0.01; 24 h: 7.22 ± 1.05 vs 1.48 ± 0.57 kat/g, P < 0.01), the level of LPO (12 h: 1.44 ± 0.63 vs 0.38 ± 0.07 μmol/g, P < 0.01; 24 h: 3.64 ± 0.83 vs 0.44 ± 0.15 μmol/g, P < 0.01) and LCP (12 h: 145.4 ± 23.0 vs 47.3 ± 5.5 μg/g wet weight, P < 0.01), as well as pulmonary ICAM-1 expression were markedly increased as compared with those in sham operation group. In comparison with those in AP group, the activity of MPO (12 h: 2.96 ± 1.04 vs 5.65 ± 0.80 kat/g, P < 0.05; 24 h: 3.68 ± 1.15 vs 7.22 ± 1.05 kat/g, P < 0.05) and the level of LPO (12 h: 0.86 ± 0.34 vs 1.44 ± 0.63 μmol/g, P < 0.05; 24 h: 1.69 ± 0.45 vs 3.64 ± 0.83 μmol/g, P < 0.05) in the lung tissues were significantly decreased, and the level of LCP (12 h: 105.9 ± 23.9 vs 145.4 ± 23.0 μg/g wet weight, P < 0.05), as well as pulmonary ICAM-1 expression was down-regulated (12 h: P < 0.05; 24 h: P < 0.01) in PGE1 group. Pathological examination revealed that intra-alveolar hemorrhage, edema and polymorphonuclear leukocytes (PMN) infiltration in the lung tissues were attenuated after PGE₁ treatment, although pancreatic damages were not alleviated.

CONCLUSION: The over-expression of ICAM-1, PMN infiltration and the release of free oxygen radicals in lung tissues may be closely related to pancreatitis-associated lung injury. PGE₁ can ameliorate lung injury by reducing ICAM-1 expression and inhibiting PMN activation and the release of free oxygen radicals.

Microcirculation disturbance affects rats with acute severe pancreatitis following lung injury

AIM: To study the effects of microcirculation disturbance (MD) on rats with acute severe pancreatitis (ASP).

METHODS: We developed ASP rat models, and anatomized separately after 1, 3, 5, 7, and 9 h. We took out blood and did hemorrheologic examination and erythrocyte osmotic fragility test, checked up the water content, capillary permeability, and genetic expression of intercellular adhesion molecule-1 (ICAM-1) in lung tissues, examined the apoptosis degree of blood vessel endothelium while we tested related gene expression of Bax and Bcl-2 in lung tissues. We did the same examination in control group.

RESULTS: The viscosity of total blood and plasma, the hematocrit, and the erythrocyte osmotic fragility were all increased. Fibrinogen was decreased. The water content in lung tissues and capillary permeability were increased. Apoptosis degree of blood vessel endothelium was increased too. ICAM-1 genetic expression moved up after 1 h and reached its peak value after 9 h.

CONCLUSION: MD plays an important role in ASP following acute lung injury (ALI). The functional damage of blood vessel endothelium, the apoptosis of capillary vessel endothelium, WBC edging-concentration and the increasing of erythrocyte fragility are the main reasons of ALI.

Membrane-bound ICAM-1 is upregulated by trypsin and contributes to leukocyte migration in acute pancreatitis

In acute pancreatitis, ICAM-1 is upregulated in various organs and contributes to the development of organ injury. To investigate the effects of pancreatic proteases on ICAM-1 expression and their role in the early process of leukocyte migration, human umbilical vein endothelial cells (HUVECs) were incubated with serum subjected to limited trypsin digestion and Wistar rats were injected with trypsin. Significant upregulation of membrane-bound ICAM-1 was seen on HUVECs incubated with trypsinated serum. Likewise, soluble ICAM-1 increased in the supernatant of HUVECs. Changes of membrane-bound ICAM-1 and soluble ICAM-1 were maximal with high concentrations of trypsin. HUVECs incubated with TNF-alpha (positive control) showed similar changes. In the pancreas and lungs of animals infused with trypsin, ICAM-1 and leukocyte sequestration were increased compared with controls. Reflecting the relevance of protease-induced ICAM-1 expression in leukocyte migration, leukocyte-endothelium interaction, as assessed by intravital microscopy, was markedly increased by trypsin. Inhibition of ICAM-1 ameliorated these changes significantly. In conclusion, trypsinated serum induces the upregulation of both membrane-bound ICAM-1 on endothelial cells and soluble ICAM-1. These changes contribute to the early steps of leukocyte migration in acute pancreatitis. The role of soluble ICAM-1 remains to be investigated.

Elevation of soluble VCAM-1 plasma levels in children with acute dengue virus infection of varying severity

Approximately 1,000 million infections with dengue viruses are estimated to occur annually. The majority of the cases develop mild disease, whereas only small proportion of the infected individuals develop severe hemorrhagic manifestations at the end of the acute phase of illness. In this study, the value of plasma levels of vascular cell adhesion molecule 1 (VCAM-1) in the pathogenesis and prognosis of dengue illness was investigated in children with dengue infections of varying severity. The plasma levels of soluble VCAM-1 (sVCAM-1) were measured in serial plasma samples obtained from 168 children aged between 7 months and 14 years with confirmed dengue infection. Of those children, 71 were suffering from dengue fever, 30 were suffering from dengue hemorrhagic fever, and 67 were suffering from dengue shock syndrome. Plasma samples obtained from 21 patients with febrile illness other than dengue served as controls. A commercially available kit (R&D Systems, Oxon, UK) was used to measure the levels of sVCAM-1 in plasma samples. sVCAM-1 was elevated during acute dengue infection, and significantly elevated among dengue shock syndrome patients as compared to dengue fever or dengue hemorrhagic fever patients (P < 0.05). Statistical analysis revealed that sVCAM-1 was associated with dengue disease severity and the time post infection (acute vs. convalescent phase) and not with age, sex, or previous exposure of the patients to dengue infection. A significant difference was found in the plasma levels of sVCAM-1 between dengue shock syndrome and dengue fever patients, however, the prognostic value of this marker in the acute stage of dengue illness proved to be limited. These data also favor to study the further elucidation of the role of sVCAM-1 in the pathogenesis of dengue infections.

Intercellular adhesion molecule-1 expression in pancreas graft and its signal transducer

AIM

To investigate the effect of neutrophil elastase inhibitor (ONO-5046) on expression of intercellular adhesion molecule-1 and transduction signal after pancreasduodenal transplantation in rats.

METHODS

ONO-5 046 was injected intravenously into experimental animal models. ICAM-1 mRNA transduction signals were detected in rat endothelial cells with regard to the effect of many reagents on expression of ICAM.

RESULTS

ICAM-1 mRNA level decreased in pancreatic grafts of experimental animals. ICAM-1 mRNA expression was increased in rat endothelial cells in vitro stimulated by NE, while that it could be inhibited by ONO-5046. Calcium ionophore enhenced ICAM-1 mRNA expression. In contrast, a phospholipase C inhibitor, calcium chelator and nuclear factor-kappa B inhibitor regulated down NE induction of ICAM-1 mRNA.

CONCLUSION

ICAM-1 expression stimulated by NE in pancreatic grafts may be associated with intracellular Ca²⁺ influx and a phospholipase C signal transduction.