Changes in disease burden and treatment reality in patients with severe asthma

BACKGROUND

Biologics are clinically available for patients with severe asthma, but changes in asthma control over time are unknown. We examined changes in disease burden and treatment in severe asthma patients.

METHODS

This retrospective study used a Japanese health insurance database (Cross Fact) and included patients aged ≥16 years treated continuously with an inhaled corticosteroid (ICS) for a diagnosis of asthma in each calendar year from 2015 to 2019. Severe asthma was defined as annual use of high-dose ICS plus one or more asthma controller medications four or more times, oral corticosteroids for ≥183 days, or biologics for ≥16 weeks. Changes in asthma exacerbations, prescriptions, and laboratory testing were examined.

RESULTS

Demographic characteristics were similar throughout the study. The number and proportion of patients with severe asthma among those with asthma increased (2724; 15.3% in 2015 vs 4485; 19.0% in 2019). The proportion of severe asthma patients with two or more asthma exacerbations decreased from 24.4% to 21.5%. Odds ratios (95% confidence interval) of ≥2 asthma exacerbations in each year compared with 2015 were 0.96 (0.85-1.08) in 2016 and 0.86 (0.76-0.97) in 2017, with significant reductions observed in subsequent years. Short-acting beta agonists and oral corticosteroid prescriptions for asthma exacerbations decreased and long-acting muscarinic antagonist and biologic prescriptions for maintenance treatment increased.

CONCLUSIONS

This study showed improvements in disease burden and treatment in severe asthma patients. There remains an unmet medical need for patients with severe asthma, given the proportion who continue to have asthma exacerbations.

A Retrospective Claims Database Study to Clarify Treatment Reality of Asthma Patients Before and After Referral to a Specialist

Purpose

Japanese guidelines recommend that patients with uncontrolled asthma be referred by non-specialists to specialists (allergists and/or pulmonologists). This study investigated the reality of clinical practice in asthma patients referred to specialists in Japan.

Patients and Methods

This was a retrospective, observational cohort study of asthma patients in a health insurance claim database (Cross Fact) referred from facilities with non-specialists to those with specialists from January 2016 to December 2018. The referred asthma patients were defined as patients with ≥4 inhaled corticosteroid (ICS)-containing prescriptions during a 1-year baseline period, with an asthma diagnosis, and who had visited a facility with specialists. Asthma exacerbation, maintenance treatment, laboratory tests, and medical procedures before and after referral were analyzed.

Results

Data for 2135 patients were extracted, of which 420 with referral codes were analyzed. The proportion of patients with asthma exacerbations was 50.2% (95% confidence interval [CI]: 45.4-55.1%) before referral and 37.4% (95% CI: 32.7-42.2%) after, a significant decrease (P<0.001; McNemar test). The proportions of patients prescribed ICS alone, long-acting beta-agonists (LABA), and ICS/LABA were lower after referral than before, but the proportions of patients prescribed long-acting muscarinic antagonists (LAMA), ICS/LABA/LAMA, and biologics increased after referral. More asthma-related laboratory tests were performed after referral, and spirometry incidence increased from 16.4% before referral to 51.4% after referral.

Conclusion

This study shows a decrease in asthma exacerbations, change in asthma treatments, and increase in laboratory tests after referral to a specialist, suggesting that referrals to specialists lead to better management of asthma.

Oral Corticosteroid Reduction Between Biologics Initiated and Non-Initiated Patients with Severe Asthma

Purpose

The oral corticosteroid (OCS)-sparing effect of several biologics (BIOs) has been shown in clinical trials. To date, no study has evaluated differences in OCS dose reduction between BIO-initiated and BIO-non-initiated patients in real-world clinical practice. We compared dose reductions in maintenance OCS between BIO-initiated and BIO-non-initiated severe asthma patients in a real-world setting.

Patients and Methods

This retrospective cohort study used the data from the Diagnosis Procedure Combination database of Medical Data Vision in Japan. Severe asthma patients with continuous use of OCS were selected from December 2015 to February 2020. The primary endpoint was the proportion reduction in daily maintenance OCS dose from Week 0 to Week 24. Analyses were performed using inverse probability treatment weighting.

Results

In total, 2927 patients were included (BIO-initiated: 239 patients, BIO-non-initiated: 2688 patients). Adjusted median (quartile [Q] 1-Q3) proportion reduction in daily maintenance OCS dose at Week 24 from the index date was 25.0% (0.0-100.0%) and 0.0% (0.0-83.3%) in the BIO-initiated and BIO-non-initiated groups, respectively (Hodges-Lehmann estimate [95% confidence interval], 0.0000% [0.0000-0.3365%]). Respective proportions of patients in the BIO-initiated and BIO-non-initiated groups achieving dose reductions from the index date in the daily maintenance OCS dose at Week 24 were >0% reduction, 56.6% and 44.1% (odds ratio [OR] 1.6554); ≥25% reduction, 50.5% and 40.6% (OR 1.4888); ≥50% reduction, 42.8% and 33.7% (OR 1.4714); and 100% reduction, 26.2% and 24.4% (OR 1.1005).

Conclusion

Among severe asthma patients, the daily dose of maintenance OCS was reduced with BIO treatment. Although a higher percentage of patients in the BIO-initiated group had an OCS reduction of ≤75% than the BIO-non-initiated group, we found no clear difference in OCS reduction. Our findings will be justified by further research that incorporates a longer observation period and variables excluded from this study.

Trial Registration

ClinicalTrials.gov (NCT05136547).

Real-World Evidence on the Diagnostic and Clinical Characteristics of Asthma in Japanese Patients with COPD: The ACO Japan Cohort Study

Introduction

The ACO Japan Cohort Study, a multicenter observational study, investigated the proportion of patients with chronic obstructive pulmonary disease (COPD) who met the Japanese Respiratory Society (JRS) asthma-COPD overlap (ACO) diagnostic criteria, characteristics of ACO and non-ACO patients, and the patient transitions between ACO/non-ACO diagnosis over 2 years.

Patients and Methods

Patients with COPD were consecutively enrolled between June and December 2018 and followed up continuously for 2 years. All participating study sites were medical institutions where respiratory specialists routinely conducted medical examinations/tests required for ACO diagnosis.

Results

Among 708 patients with COPD, 101 (14.3%), 118 (16.7%), and 125 (17.7%) were diagnosed with ACO at registration, 1 year, and 2 years, respectively. In total, 22.6% of patients lacked the data necessary for ACO diagnosis throughout the 2 years. Among patients who had the necessary data for ACO diagnosis, 24.7% were diagnosed with ACO at 2 years. More ACO patients had moderate or severe exacerbations in the past year than non-ACO patients at registration (15.8% vs 6.3%, p = 0.049) and 1 year (19.4% vs 7.6%, p = 0.025). ACO patients had a greater decrease in mean forced expiratory volume in one second over 2 years than non-ACO patients (-92.0 vs 43.4 mL). Among patients diagnosed with ACO at registration, 21.4% transitioned to non-ACO after 1 year. Conversely, almost all non-ACO patients at registration remained non-ACO after 1 year.

Conclusion

COPD patients with ACO determined by the JRS criteria had a high risk of exacerbations and a rapid decline in respiratory function, indicating that the JRS criteria for ACO are useful for identifying high-risk COPD patients. Testing necessary for ACO diagnosis is insufficiently performed even in real-world clinical practice of COPD specialists.

Urine osmolality predicts worsening renal function and poor prognosis in acute decompensated heart failure

Background/Purpose

Worsening renal function (WRF) can sometimes occur in the patients with acute decompensated heart failure (ADHF) and increase the risk of morbidity and mortality (1). In a previous study, it was reported that fractional excretion of sodium (FENa) reflects net sodium reabsorption from nephron segments and predicts WRF during treating ADHF (2). On the other hand, recently the new drugs which approach urine concentration mechanism and affect urine osmolality (U-OSM), such as tolvaptan and sodium-glucose cotransporter-2 inhibitor, have begun to be widely used as treatment of heart failure. Thus, we focused on U-OSM, which reflects not only sodium handling but also water excretion controlled by the collecting duct, and evaluated the association between WRF and U-OSM. Moreover, previous studies have demonstrated that FENa, fractional excretion of urea nitrogen and transtubular potassium concentration gradient are markers for long-term prognosis in patients with ADHF (3–5). Therefore, we also studied whether U-OSM can predict prognosis in ADHF.

Methods

A total of 157 patients admitted to our hospital because of a primary diagnosis of ADHF from February 2020 through July 2021 were retrospectively reviewed. U-OSM in the spot urinary samples were examined within 72 hours after admission. U-OSM was calculated based on the following validated formula (6): U-OSM = 1.07 × {2 × [urine sodium (mEq/L)] + [urine urea nitrogen (mg/dL)]/2.8 + [urine creatinine (mg/dl)] × 2/3} + 16.2. The primary outcome was the occurrence of WRF during hospitalization. WRF was defined as increased serum creatinine ≥0.3 mg/dL from baseline (7). The secondary outcome was the occurrence of ADHF readmission and all-cause death within 180 days after discharge.

Results

Primary Outcome. WRF developed in 46% of all patients. In the patients that developed WRF during hospitalization, U-OSM was significantly lower than in the patients without WRF (366±106 mOsm/L versus 430±128 mOsm/L; P&lt;0.001). Receiver operating characteristic curve analysis revealed the optimal cutoff values of U-OSM was 403 mOsm/L (AUC 0.64; 95% CI: 0.56–0.72; P&lt;0.001) to predict the WRF (Figure 1). On multivariable logistic regression analysis, U-OSM (OR, 1.99, 95% CI: 1.27–3.12; p=0.003) and serum creatinine (OR, 1.00, 95% CI: 0.99–1.00; P=0.009) were independent predictors of WRF.

Secondary Outcome. There were 34 patients (22%) readmitted and 9 patients (6%) died within 180 days after discharge. ROC curve analysis revealed the optimal cutoff values of U-OSM as 349 mOsm/L (C-statistic 0.74; 95% CI: 0.65–0.83; P&lt;0.001) to predict ADHF readmission and all-cause death within 180 days (Figure 2A). On Kaplan-Meier analysis, the secondary outcome was significantly higher in patients with U-OSM&lt;349 mOsm/L (u-OSM≥349, 57%, U-OSM&lt;349, 43%; HR, 0.99; 95% CI: 0.99–1.00, P&lt;0.001) (Figure 2B).

Conclusion

U-OSM on admission may be a predictor of WRF and a prognostic marker in ADHF patients.

Funding Acknowledgement

Type of funding sources: None.

Effect of timing of bronchodilator therapy initiation on exacerbations in patients with chronic obstructive pulmonary disease: a retrospective cohort study

Background

The benefit of prompt vs delayed treatment initiation with inhaled long-acting bronchodilators in reducing exacerbations in chronic obstructive pulmonary disease (COPD) is unclear. This study aimed to investigate if long-acting bronchodilator therapy initiation within 30 days of COPD diagnosis reduces exacerbation risk in patients with COPD.

Methods

This was a retrospective cohort study of patients with COPD based on claims and electronic medical records data extracted from the Real World Data database. The index date (day 0) was the date of the first confirmed inpatient or outpatient COPD diagnosis between January 1, 2005, and December 31, 2018. Patients with COPD without an asthma diagnosis and aged ≥ 40 years at the index date were included. Patients who initiated inhaled long-acting bronchodilator therapy within the first 30 days (day 0 to day 29) were categorized into the “prompt therapy” group and the rest into the “delayed therapy” group. Time from day 30 post-diagnosis to the first exacerbation and annual exacerbation rate (AER) were evaluated for the overall population and those stratified by COPD phenotype, including chronic bronchitis (CB) and emphysema.

Results

Compared with the delayed therapy group (n = 1516), time to first exacerbation was prolonged (hazard ratio 0.78; 95% confidence interval [CI] [0.70, 0.87]) and annual rates of moderate or severe exacerbations were lower (rate ratio 0.74; 95% CI [0.65, 0.84]) in the prompt therapy group (n = 1466). Similarly, time to first exacerbation was prolonged and AERs were lower in the prompt therapy group in the subgroups of patients with CB or emphysema.

Conclusions

This is the first study to demonstrate a prolonged time to first exacerbation upon initiation of long-acting bronchodilators within 30 days of COPD diagnosis. A beneficial effect was also observed in patients with CB and emphysema. Our data support advising patients to initiate long-acting bronchodilators soon after COPD diagnosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-02184-6.

Real-World Status of Medical Care and Treatment of Chronic Obstructive Pulmonary Disease by Respiratory Specialists in Japan

INTRODUCTION

The ACO Registry Study was a multicenter, prospective, observational cohort study aiming to clarify the situation of asthma-chronic obstructive pulmonary disease (COPD) overlap (ACO) within the COPD population using the Japanese Respiratory Society (JRS) criteria. We reported the proportion of patients who met the ACO criteria among the COPD population at study registration.

METHODS

Using data collected at registration, we investigated the implementation of each diagnostic examination/test required for ACO diagnosis in the full analysis set. Among patients with data necessary for ACO diagnosis, ACO/non-ACO patients with/without asthma diagnosed by a physician and proportions of inhaled corticosteroid (ICS) treatments for COPD were calculated.

RESULTS

Of 708 patients analyzed, 396 (55.9%) had the data necessary for ACO diagnosis, and 312 (44.1%) did not. The proportions of patients who underwent laboratory and respiratory function tests (peripheral blood eosinophil count [79.8%], fractional exhaled nitric oxide [63.7%], airway reversibility [46.8%], and total immunoglobulin [Ig] E/specific IgE [33.3%]) were lower than those who underwent subjective examinations (perennial allergic rhinitis [100%], asthma before age 40 years [97.2%], and variable/paroxysmal respiratory symptoms [94.5%]). Among patients with the data necessary for ACO diagnosis and without asthma complications according to the physician's diagnosis, 15.1% (33/219) met the ACO criteria. Of patients who met the ACO criteria, 74.3% (75/101) received ICS, and 25.7% (26/101) did not. By comparison, among patients who did not meet the ACO criteria, 35.6% (105/295) were receiving ICS, and 64.4% (190/295) were not.

CONCLUSIONS

The proportion of objective laboratory and physiological tests was lower than expected, despite study sites having the clinical resources for objective tests. Most ACO patients were being treated with ICS as recommended in the JRS treatment guidelines. Attempts should be made to further increase the proper use of ICS among these patients in Japan.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03577795.

Regional differences in the incidence of asthma exacerbations in Japan: A heat map analysis of healthcare insurance claims data

BACKGROUND

In Japan, regional differences in asthma mortality have been reported; however, regional differences in asthma exacerbations have not been studied extensively. Therefore, using a health insurance claims database, we investigated the regional differences in the incidence of asthma exacerbations in Japan.

METHODS

This study used data from Medi-Scope (Japan Medical Information Research Institute Inc., Japan)-a nationwide health insurance claims database. Patients with asthma at the index date (the latest date of an asthma-related prescription with an asthma diagnosis before October 1, 2018) were included in the analysis. The pre-index period was defined as 1 year before the index date, and the follow-up period as 1 year after the index date. The incidence of asthma exacerbation events was analyzed for each region.

RESULTS

The primary analysis population comprised 24,883 patients who were continuously prescribed ICS or ICS/LABA at least four times during the pre-index period. The incidence rate of asthma exacerbations with hospitalization was the highest in Chugoku (2.95/100 person-years [95% CI, 1.97-4.43]) and the lowest in Kanto (1.52/100 person-years [95% CI, 1.26-1.83]). The incidence rate of asthma exacerbations for the composite outcome of hospitalization, injectable corticosteroid prescription, and oral corticosteroid burst was the highest in Fukui (105.00/100 person-years [95% CI, 64.53-170.85]) and the lowest in Nagasaki (15.69/100 person-years [95% CI, 10.84-22.72]).

CONCLUSIONS

Regional differences in the incidence of asthma exacerbations as well as their treatments were observed in Japan.

Effects of Sulfonylureas on Periodontopathic Bacteria-Induced Inflammation

Interleukin-1β (IL-1β) is an inflammatory cytokine produced by monocytes/macrophages and is closely associated with periodontal diseases. The NLRP3 inflammasome is involved in IL-1β activation through pro-IL-1β processing and pyroptotic cell death in bacterial infection. Recently, glyburide, a hypoglycemic sulfonylurea, has been reported to reduce IL-1β activation by suppressing activation of the NLRP3 inflammasome. Therefore, we evaluated the possibility of targeting the NLRP3 inflammasome pathway by glyburide to suppress periodontal pathogen-induced inflammation. THP-1 cells (a human monocyte cell line) were differentiated to macrophage-like cells by treatment with phorbol 12-myristate 13-acetate and stimulated by periodontopathic bacteria, Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, or Fusobacterium nucleatum, in the presence of glyburide. IL-1β and caspase-1 expression in the cells and culture supernatants were analyzed by Western blotting and enzyme-linked immunosorbent assay, and cell death was analyzed by lactate dehydrogenase assay. Stimulation of THP-1 macrophage-like cells with every periodontopathic bacteria induced IL-1β secretion without cell death, which was suppressed by the NLRP3 inhibitor, MCC950, and caspase-1 inhibitor, z-YVAD-FMK. Glyburide treatment suppressed IL-1β expression in culture supernatants and enhanced intracellular IL-1β expression, suggesting that glyburide may have inhibited IL-1β secretion. Subsequently, a periodontitis rat model was generated by injecting periodontal bacteria into the gingiva, which was analyzed histologically. Oral administration of glyburide significantly suppressed the infiltration of inflammatory cells and the number of osteoclasts in the alveolar bone compared with the control. In addition to glyburide, glimepiride was shown to suppress the release of IL-1β from THP-1 macrophage-like cells, whereas other sulfonylureas (tolbutamide and gliclazide) or other hypoglycemic drugs belonging to the biguanide family, such as metformin, failed to suppress IL-1β release. Our results suggest that pharmacological targeting of the NLRP3 pathway may be a strategy for suppressing periodontal diseases.

Ultrafast slow-light tuning beyond the carrier lifetime using photonic crystal waveguides

We demonstrate ultrafast delay tuning of a slow-light pulse with a response time <10 ps. This is achieved using two types of slow light: dispersion-compensated slow light for the signal pulse, and low-dispersion slow light to enhance nonlinear effects of the control pulse. These two types of slow light are generated simultaneously in Si lattice-shifted photonic crystal waveguides, arising from flat and straight photonic bands, respectively. The control pulse blueshifts the signal pulse spectrum, through dynamic tuning caused by the plasma effect of two-photon-absorption-induced carriers. This changes the delay by up to 10 ps only when the two pulses overlap within the waveguide and enables ultrafast tuning that is not limited by the carrier lifetime. Using this, we succeeded in tuning the delay of one target pulse within a pulse train with 12 ps intervals.

Dynamics of primary and secondary microbubbles created by laser-induced breakdown of an optically trapped nanoparticle

Laser-induced breakdown of an optically trapped nanoparticle is a unique system for studying cavitation dynamics. It offers additional degrees of freedom, namely the nanoparticle material, its size, and the relative position between the laser focus and the center of the optically trapped nanoparticle. We quantify the spatial and temporal dynamics of the cavitation and secondary bubbles created in this system and use hydrodynamic modeling to quantify the observed dynamic shear stress of the expanding bubble. In the final stage of bubble collapse, we visualize the formation of multiple submicrometer secondary bubbles around the toroidal bubble on the substrate. We show that the pattern of the secondary bubbles typically has its circular symmetry broken along an axis whose unique angle rotates over time. This is a result of vorticity along the jet towards the boundary upon bubble collapse near solid boundaries.

An increase in the serum amylase level in patients after peroral double-balloon enteroscopy: an association with the development of pancreatitis

BACKGROUND AND STUDY AIMS

Double-balloon enteroscopy (DBE) is a novel technique that allows the enteroscope to be inserted deep into the small intestine. The procedure has been thought to be safe, but cases of acute pancreatitis after peroral DBE have recently been observed. The aim of this study was to confirm the occurrence of hyperamylasemia after peroral DBE.

PATIENTS AND METHODS

Peroral DBE was carried out in 13 patients from July 2005 to February 2006. Blood samples were taken before and 3 h after the procedure, and serum pancreatic amylase levels were measured. The patients were also evaluated for pancreatic-type abdominal pain after the procedure. Hyperamylasemia after peroral DBE was defined as an elevation of the serum pancreatic amylase level to more than the upper normal limit and twice the level before the procedure. Pancreatitis was diagnosed on the basis of both pancreatic-type abdominal pain and hyperamylasemia.

RESULTS

Hyperamylasemia after peroral DBE occurred in six patients (46.2 %). One of the six patients with hyperamylasemia had pancreatic-type abdominal pain after the procedure and developed acute pancreatitis. The average procedure time was 105 min (range 65 - 155 min) in the patients with hyperamylasemia, and did not significantly differ from that in the group without hyperamylasemia (99 min).

CONCLUSIONS

Hyperamylasemia after peroral DBE occurs frequently and may be associated with development of pancreatitis.

Anti-monocyte chemoattractant protein 1 gene therapy attenuates experimental chronic pancreatitis induced by dibutyltin dichloride in rats

BACKGROUND

Monocyte chemoattractant protein 1 (MCP-1) is a member of the C-C chemokine family and exerts strong chemoattractant activity in monocytes, macrophages, and lymphocytes. Rat pancreatic fibrosis induced by dibutyltin dichloride (DBTC) is considered to be an appropriate chronic pancreatitis model histologically and enzymatically, as has demonstrated in a previous study.

AIM

We examined the effect of human dominant negative inhibitor of MCP-1 (mutant MCP-1) on progression of chronic pancreatitis induced by DBTC in a rat model.

METHODS

We used the experimental model of chronic pancreatitis induced by DBTC in rats. Mutant MCP-1 or empty plasmid at a dose of 50 microg/body weight was administrated into rat thigh muscles on days 4, 11, and 18 after administration of DBTC. On days 14 and 28, we evaluated the effect of mutant MCP-1 morphologically and biochemically.

RESULTS

The mutant MCP-1 treated group inhibited early pancreatic inflammation and later pancreatic fibrosis histologically, and showed a decrease in serum MCP-1 concentration, intrapancreatic hydroxyproline, alpha-smooth muscle actin, and an increase in intrapancreatic amylase and protein content compared with the empty plasmid treated group. The mutant MCP-1 group also inhibited intrapancreatic mRNA expression of cytokines and chemokines.

CONCLUSIONS

: Our findings suggest that monocyte/macrophage recruitment and the systemic MCP-1 signal pathway contribute to progression of chronic pancreatitis, and that blockade of MCP-1 may suppress the development of pancreatic fibrosis.

Nasal glucagon delivery using microcrystalline cellulose in healthy volunteers

We developed an intranasal powder form of glucagon to improve metabolic status and fatty liver in patients with pancreatectomy. Microcrystalline cellulose, which is commonly used in commercial preparations for allergic rhinitis was used as an absorption enhancer. We compared the intranasal powder form with some spray solutions of glucagon with regard to glucagon absorption, concentration of blood glucose, stability and nasal irritation. The absorption of glucagon from the spray solution including 1.5% sodium glycocholate or 1% sodium caprate was 1.3- and 2.6-fold higher than that from the powder form mixed with microcrystalline cellulose at a ratio of 1:69, respectively. The C(max) values of plasma glucose were 2.18, 3.39 and 1.56 mmol l(-1) in the spray solutions including sodium glycocholate and sodium caprate and in the powder form, respectively. However, glucagon in spray solutions was unstable, but that in the powder form was stable at 5 and 25 degrees C for at least 84 days. The spray solution caused strong irritation, but the powder form did not. These results suggested usefulness of the powder form of glucagon for treatment of pancreatectomized patients.

Circulating concentrations of the adipocyte protein adiponectin are decreased in parallel with reduced insulin sensitivity during the progression to type 2 diabetes in rhesus monkeys

Adiponectin is an adipose-specific plasma protein whose plasma concentrations are decreased in obese subjects and type 2 diabetic patients. This protein possesses putative antiatherogenic and anti-inflammatory properties. In the current study, we have analyzed the relationship between adiponectin and insulin resistance in rhesus monkeys (Macaca mulatta), which spontaneously develop obesity and which subsequently frequently progress to overt type 2 diabetes. The plasma levels of adiponectin were decreased in obese and diabetic monkeys as in humans. Prospective longitudinal studies revealed that the plasma levels of adiponectin declined at an early phase of obesity and remained decreased after the development of type 2 diabetes. Hyperinsulinemic-euglycemic clamp studies revealed that the obese monkeys with lower plasma adiponectin showed significantly lower insulin-stimulated peripheral glucose uptake (M rate). The plasma levels of adiponectin were significantly correlated to M rate (r = 0.66, P < 0.001). Longitudinally, the plasma adiponectin decreased in parallel to the progression of insulin resistance. No clear association was found between the plasma levels of adiponectin and its mRNA levels in adipose tissue. These results suggest that reduction in circulating adiponectin may be related to the development of insulin resistance.

Adipocyte-derived plasma protein, adiponectin, suppresses lipid accumulation and class A scavenger receptor expression in human monocyte-derived macrophages

BACKGROUND

Excessive lipid accumulation in macrophages plays an important role in the development of atherosclerosis. Recently, we discovered an adipocyte-specific plasma protein, adiponectin, that is decreased in patients with coronary artery disease. We previously demonstrated that adiponectin acts as a modulator for proinflammatory stimuli and inhibits monocyte adhesion to endothelial cells. The present study investigated the effects of adiponectin on lipid accumulation in human monocyte-derived macrophages.

METHODS AND RESULTS

Human monocytes were differentiated into macrophages by incubation in human type AB serum for 7 days, and the effects of adiponectin were investigated at different time intervals. Treatment with physiological concentrations of adiponectin reduced intracellular cholesteryl ester content, as determined using the enzymatic, fluorometric method. The adiponectin-treated macrophages contained fewer lipid droplets stained by oil red O. Adiponectin suppressed the expression of the class A macrophage scavenger receptor (MSR) at both mRNA and protein levels by Northern and immunoblot analyses, respectively, without affecting the expression of CD36, which was quantified by flow cytometry. Adiponectin reduced the class A MSR promoter activity, as measured by luciferase reporter assay. Adiponectin treatment dose-dependently decreased class A MSR ligand binding and uptake activities. The mRNA level of lipoprotein lipase as a marker of macrophage differentiation was decreased by adiponectin treatment, but that of apolipoprotein E was not altered. Adiponectin was detected around macrophages in the human injured aorta by immunohistochemistry.

CONCLUSIONS

The adipocyte-derived plasma protein adiponectin suppressed macrophage-to-foam cell transformation, suggesting that adiponectin may act as a modulator for macrophage-to-foam cell transformation.

Hyperoxia inhibits oxidant-induced apoptosis in lung epithelial cells

It has previously been shown that hyperoxia induces nonapoptotic cell death in cultured lung epithelial cells, whereas hydrogen peroxide (H(2)O(2)) and paraquat cause apoptosis. To test whether pathways leading to oxidative apoptosis in epithelial cells are sensitive to molecular O(2), A549 cells were exposed to 95% O(2) prior to exposure to lethal concentrations of H(2)O(2). The extent of H(2)O(2)-induced apoptosis was significantly reduced in cells preexposed to hyperoxia compared with room-air controls. Preexposure of the hyperoxia-resistant HeLa-80 cell line to 80% O(2) also inhibited oxidant-induced apoptosis, suggesting that this inhibition is not due to O(2) toxicity. Because hyperoxia generates reactive oxygen species and activates the redox-sensitive transcription factor nuclear factor kappa B (NF-kappa B), the role of antioxidant enzymes and NF-kappa B were examined in this inhibitory process. The onset of inhibition appeared to be directly related to the degradation of I kappa B and subsequent activation of NF-kappa B (either by hyperoxia or TNF-alpha), whereas no significant up-regulation of endogenous antioxidant enzyme activities was found. In addition, suppression of NF-kappa B activities by transfecting A549 cells with a dominant-negative mutant construct of I kappa B significantly augmented the extent of H(2)O(2)-induced apoptosis. These data suggest that hyperoxia inhibits oxidant-induced apoptosis and that this inhibition is mediated by NF-kappa B.

Survival mechanisms induced by 12-O-tetradecanoylphorbol-13-acetate in normal human melanocytes include inhibition of apoptosis and increased Bcl-2 expression

Phorbol esters, which activate protein kinase C, stimulate the growth of normal human melanocytes yet inhibit the growth of most melanoma cells. We investigated whether apoptosis mediates the effects of 12-O-tetradecanoylphorbol-13-acetate (TPA) on melanocyte and melanoma cell growth. Few apoptotic cells were present when melanocytes were cultured with TPA. Upon removal of TPA, the number of apoptotic cells increased over 10 days. Addition of TPA did not induce apoptosis in a metastatic melanoma cell line, Demel, although it strongly inhibited its growth. Protection of normal melanocytes from apoptosis was associated with high levels of Bcl-2. Following withdrawal of TPA from melanocytes, the expression of Bcl-2 decreased steadily. Bax and Bcl-X(L) levels did not differ between melanoma cells or melanocytes and were unaffected by the addition of TPA. These results suggest that TPA plays an important role in stimulating the growth of melanocytes by promoting anti-apoptotic mechanisms associated with high levels of Bcl-2.

Adiponectin, an adipocyte-derived plasma protein, inhibits endothelial NF-kappaB signaling through a cAMP-dependent pathway

BACKGROUND

Among the many adipocyte-derived endocrine factors, we found an adipocyte-derived plasma protein, adiponectin, that was decreased in obesity. We recently demonstrated that adiponectin inhibited tumor necrosis factor-alpha (TNF-alpha)-induced expression of endothelial adhesion molecules and that plasma adiponectin level was reduced in patients with coronary artery disease (CIRCULATION: 1999;100:2473-2476). However, the intracellular signal by which adiponectin suppressed adhesion molecule expression was not elucidated. The present study investigated the mechanism of modulation for endothelial function by adiponectin.

METHODS AND RESULTS

The interaction between adiponectin and human aortic endothelial cells (HAECs) was estimated by cell ELISA using biotinylated adiponectin. HAECs were preincubated for 18 hours with 50 microg/mL of adiponectin, then exposed to TNF-alpha (10 U/mL) or vehicle for the times indicated. NF-kappaB-DNA binding activity was determined by electrophoretic mobility shift assays. TNF-alpha-inducible phosphorylation signals were detected by immunoblotting. Adiponectin specifically bound to HAECs in a saturable manner and inhibited TNF-alpha-induced mRNA expression of monocyte adhesion molecules without affecting the interaction between TNF-alpha and its receptors. Adiponectin suppressed TNF-alpha-induced IkappaB-alpha phosphorylation and subsequent NF-kappaB activation without affecting other TNF-alpha-mediated phosphorylation signals, including Jun N-terminal kinase, p38 kinase, and Akt kinase. This inhibitory effect of adiponectin is accompanied by cAMP accumulation and is blocked by either adenylate cyclase inhibitor or protein kinase A (PKA) inhibitor.

CONCLUSIONS

These observations raise the possibility that adiponectin, which is naturally present in the blood stream, modulates the inflammatory response of endothelial cells through cross talk between cAMP-PKA and NF-kappaB signaling pathways.

Genomic structure and mutations in adipose-specific gene, adiponectin

BACKGROUND

Adiponectin is a collagen-like plasma protein specifically synthesized in adipose tissue. Plasma adiponectin concentrations are decreased in obesity whereas it is adipose-specific.

OBJECTIVE

To clarify the significance of the genetic variations in adiponectin gene on its plasma concentrations and obesity.

SUBJECTS

Two hundred and nineteen unrelated adult Japanese subjects (123 men and 96 women, age: 20-83 y, BMI: 16-43 kg/m2) including 77 obese subjects (BMI>26.4 kg/m2).

MEASUREMENT

Human adiponectin gene was isolated from PAC DNA pools. Mutations in the adiponectin gene were screened by direct sequencing or restriction-fragment polymorphism. The levels of plasma adiponectin were determined by the enzyme-linked immunosorbent assay (ELISA).

RESULTS

Adiponectin gene spanned 17 kb on chromosome 3q27, consisting of three exons and two introns. Within 2.1 kb of the 5'-flanking region, there were two octamer elements present in the promoter of adipsin. Two nucleotide changes were identified. One was a polymorphism (G/T) occurring in exon 2, and the other was a missense mutation (R112C) in exon 3. The mean plasma adiponectin levels of the subjects carrying G allele were low (G/G: 4.5 microg/ml; G/T: 5.9 microg/ml; and T/T: 6.3 microg/ml), but were not statistically significant. The allelic frequency between the obese and the non-obese showed no significant difference. The subject carrying R112C mutation showed markedly low concentration of plasma adiponectin.

CONCLUSION

Two nucleotide changes have been identified in the adiponectin gene. G/T polymorphism in exon 2 was associated with neither plasma adiponectin concentrations nor the presence of obesity. A subject carrying missense mutation (R112C) showed markedly low plasma adiponectin concentration.

Plasma concentrations of a novel, adipose-specific protein, adiponectin, in type 2 diabetic patients

Adiponectin is a novel, adipose-specific protein abundantly present in the circulation, and it has antiatherogenic properties. We analyzed the plasma adiponectin concentrations in age- and body mass index (BMI)-matched nondiabetic and type 2 diabetic subjects with and without coronary artery disease (CAD). Plasma levels of adiponectin in the diabetic subjects without CAD were lower than those in nondiabetic subjects (6.6+/-0.4 versus 7.9+/-0.5 microg/mL in men, 7.6+/-0.7 versus 11.7+/-1.0 microg/mL in women; P<0.001). The plasma adiponectin concentrations of diabetic patients with CAD were lower than those of diabetic patients without CAD (4.0+/-0.4 versus 6.6+/-0.4 microg/mL, P<0.001 in men; 6.3+/-0.8 versus 7.6+/-0. 7 microg/mL in women). In contrast, plasma levels of leptin did not differ between diabetic patients with and without CAD. The presence of microangiopathy did not affect the plasma adiponectin levels in diabetic patients. Significant, univariate, inverse correlations were observed between adiponectin levels and fasting plasma insulin (r=-0.18, P<0.01) and glucose (r=-0.26, P<0.001) levels. In multivariate analysis, plasma insulin did not independently affect the plasma adiponectin levels. BMI, serum triglyceride concentration, and the presence of diabetes or CAD remained significantly related to plasma adiponectin concentrations. Weight reduction significantly elevated plasma adiponectin levels in the diabetic subjects as well as the nondiabetic subjects. These results suggest that the decreased plasma adiponectin concentrations in diabetes may be an indicator of macroangiopathy.

An adipocyte-derived plasma protein, adiponectin, adheres to injured vascular walls

Adipose tissue secretes a variety of proteins into the bloodstream. We have previously reported a novel cDNA, apM1 (adipose most abundant gene transcript 1), which is specifically and abundantly expressed in adipose tissue [1]. Primary structure analysis predicted that the apM1 gene product possesses significant homology to collagens VIII, X and complement factor C1q, and we named it adiponectin. In the current study, we analyzed characteristics of adiponectin in vitro and in vivo. Adiponectin protein was proved to be secreted into the medium when the cDNA was transfected to COS cells. Anti-adiponectin cross-reactivities were abundantly detected in the human plasma. In solid-phase binding assays, adiponectin specifically bound to collagen types I, III and V, which are present in vascular intima. Immunohistochemical analysis revealed that adiponectin was detected in the walls of the catheter-injured vessels but not in the intact vascular walls. These data suggest that adiponectin is a plasma protein produced by adipose tissue and accumulates in vascular walls when the endothelial barrier is injured.

Novel modulator for endothelial adhesion molecules: adipocyte-derived plasma protein adiponectin

BACKGROUND

Among the many adipocyte-derived endocrine factors, we recently found an adipocyte-specific secretory protein, adiponectin, which was decreased in obesity. Although obesity is associated with increased cardiovascular mortality and morbidity, the molecular basis for the link between obesity and vascular disease has not been fully clarified. The present study investigated whether adiponectin could modulate endothelial function and relate to coronary disease.

METHODS AND RESULTS

For the in vitro study, human aortic endothelial cells (HAECs) were preincubated for 18 hours with the indicated amount of adiponectin, then exposed to tumor necrosis factor-alpha (TNF-alpha) (10 U/mL) or vehicle for the times indicated. The adhesion of human monocytic cell line THP-1 cells to HAECs was determined by adhesion assay. The surface expression of vascular cell adhesion molecule-1 (VCAM-1), endothelial-leukocyte adhesion molecule-1 (E-selectin), and intracellular adhesion molecule-1 (ICAM-1) was measured by cell ELISA. Physiological concentrations of adiponectin dose-dependently inhibited TNF-alpha-induced THP-1 adhesion and expression of VCAM-1, E-selectin, and ICAM-1 on HAECs. For the in vivo study, the concentrations of adiponectin in human plasma were determined by a sandwich ELISA system that we recently developed. Plasma adiponectin concentrations were significantly lower in patients with coronary artery disease than those in age- and body mass index-adjusted control subjects.

CONCLUSIONS

These observations suggest that adiponectin modulates endothelial inflammatory response and that the measurement of plasma adiponectin levels may be helpful in assessment of CAD risk.

Paradoxical decrease of an adipose-specific protein, adiponectin, in obesity

We isolated the human adipose-specific and most abundant gene transcript, apM1 (Maeda, K., et al., Biochem. Biophys. Res. Commun. 221, 286-289, 1996). The apM1 gene product was a kind of soluble matrix protein, which we named adiponectin. To quantitate the plasma adiponectin concentration, we have produced monoclonal and polyclonal antibodies for human adiponectin and developed an enzyme-linked immunosorbent assay (ELISA) system. Adiponectin was abundantly present in the plasma of healthy volunteers in the range from 1.9 to 17.0 mg/ml. Plasma concentrations of adiponectin in obese subjects were significantly lower than those in non-obese subjects, although adiponectin is secreted only from adipose tissue. The ELISA system developed in this study will be useful for elucidating the physiological and pathophysiological role of adiponectin in humans.

Role of adipocytokines on the pathogenesis of atherosclerosis in visceral obesity

Obesity which is defined as accumulation of excess body fat, is a major cause of atherosclerotic vascular disease in industrial countries. Recent advances in the biology of adipose tissue have revealed that adipose tissue is not simply an energy storage organ but it also secretes a variety of molecules which affect the metabolism of the whole body. Through a systematic search of active genes in adipose tissue, we found that adipose tissue, especially visceral fat expressed numerous genes for secretory proteins (about 30% of total genes analyzed). Among them, plasminogen activator-1 (PAI-1), which is a regulator of the fibrinolytic system, was overexpressed in the visceral fat in an animal model of obesity. Plasma levels of PAI-1 were closely correlated with visceral fat adiposity. Thus, PAI-1 secreted from visceral fat may play some role in thrombotic vascular disease in visceral obesity. Adiponectin, a novel adipose-specific gene product, which has a matrix-like structure, is abundantly present in the bloodstream. Dysregulated secretion of adiponectin may be related to vascular disease in obesity. Biologically active molecules secreted from adipose tissue (adipocytokines) may have important roles in the development of atherosclerotic disease in obesity.

Autoimmune pancreatitis: radiologic findings in three histologically proven cases

We describe the radiologic findings of autoimmune pancreatitis, a rare variant of pancreatitis. The radiologic findings of autoimmune pancreatitis are pathognomonic and very different from those of ordinary types of acute or chronic pancreatitis. This condition is a new clinical entity that is effectively treated with steroid therapy. It is important to recognize the radiologic characteristics of autoimmune pancreatitis to avoid surgical resection and start steroid therapy.

Regulation of the cell cycle at the G2/M boundary in metastatic melanoma cells by 12-O-tetradecanoyl phorbol-13-acetate (TPA) by blocking p34cdc2 kinase activity

12-O-Tetradecanoyl phorbol-13-acetate (TPA) inhibits the growth of most malignant melanoma cells but stimulates the growth of normal human melanocytes. We previously showed that addition of TPA inhibits the growth of the human metastatic melanoma cell line, Demel, by blocking cells at both the G1/S and G2/M cell cycle transitions (D. L. Coppock et al., 1992, Cell Growth Differ. 3, 485-494). To examine the G2/M transition, we developed a method to synchronize the cells in early S phase using Lovastatin and mevalonate, followed by treatment with hydroxyurea (HU). TPA (30 nM) was effective in blocking cells from entering mitosis and reentering G1 when added up to the end of G2. These cells arrested in G2. Examination of the levels of cyclins A and B1 demonstrated that the levels of these cyclins were not limiting for entrance into M. However, the addition of TPA blocked the increase in p34(cdc2)/cyclin B1 kinase activity. In cells treated with TPA, most p34(cdc2) was found in the slowly migrating forms on Western blots, which contained increased levels of phosphotyrosine. In addition, the level of the cyclin-dependent kinase inhibitor p21(Cip1/Waf1), but not of p27(Kip1), was increased. We examined the expression of protein kinase C (PKC) isoforms in Demel cells using Western blots to understand which types were involved in the G2 arrest. Demel cells expressed the PKC alpha, betaI, betaII, delta, epsilon, iota/lambda, zeta, and mu isozymes. PKC eta and PKC theta were not detected. Addition of TPA did not completely down regulate any PKC isozymes over a 12-h period in these synchronized cells. PKC alpha, betaI, betaII, delta, and epsilon isozymes were translocated to the membrane fraction from the cytosolic fraction when treated with TPA. PKC delta appeared as a doublet and the addition of TPA shifted a majority to the slower migrating form. The level of PKC mu was constant; however, a slow mobility form was observed in TPA-treated cells. This reduced mobility was at least partially due to phosphorylation. Thus, the arrest of growth in G2 appears to be due to the inhibition of the p34(cdc2) kinase activity which is associated with the increased expression of p21(Cip1/Waf1) and increased phosphorylation on tyrosine of p34(cdc2). This arrest, in turn, is associated with a shift of PKC isozymes PKC alpha, PKC betaI, PKC betaII, PKC delta, PKC epsilon, and PKC mu to the membrane fraction which is induced by addition of TPA.

Establishment and immunocharacterization of an immortalized pancreatic cell line derived from the H-2Kb-tsA58 transgenic mouse

This study describes the establishment and characterization of an immortalized cell line derived from the pancreas of an adult H-2Kb-tsA58 transgenic mouse. These cells, designated IMPAN for IMmortalized PANcreatic cells, displayed a cobblestone appearance typical of confluent epithelial cells and a distinct polarity in the organization of their cytoplasmic organelles. Immunocytochemical studies revealed that all IMPAN cells stained positively for a wide range of markers characteristic of pancreatic acinar cells, namely the secretory products alpha-amylase, chymotrypsinogen, DNAse, the lectinlike secretory protein PAP (pancreatitis associated protein), and the zymogen granule membrane proteins GP-2 and gp300. They also stained positively for carbonic anhydrase II and cytokeratin 19, two proteins characteristic of pancreatic duct cells, as well as for rab3A, a small GTP-binding protein specifically localized in pancreatic islet cells. No reactivity was ever obtained with insulin antibodies. Taken together, these results show that the IMPAN cells exhibit a phenotype comparable to exocrine pancreatic acinar cells. However the expression of some proteins more specific to duct and islet cells make them similar to in vivo or in vitro growing acinar cells. The cell line should be a valuable model to study the mechanisms of growth, differentiation, and transformation of the exocrine pancreatic acinar cell.

Endogenous arachidonic acid release and pancreatic amylase secretion

Recent studies have suggested the involvement of phospholipase A2 (PLA2) in pancreatic amylase secretion. The present study was designed to investigate the secretory role of arachidonic acid (AA) in carbachol (Cch)-stimulated rat pancreatic acini and its origin. From enzymatic assays, PLA2 and diacylglycerol (DAG) lipase were activated by Cch and respectively inhibited by the PLA2 inhibitors, mepacrine and aristolochic acid, and by the DAG lipase inhibitor, RHC 80267. Melittin-activated PLA2 activity was also inhibited by the PLA2 inhibitors. Cch-stimulated endogenous AA release from pancreatic acini was partially inhibited by 150 microM RHC 80267 and by 150 microM mepacrine or 200 microM aristolochic acid and totally inhibited by a combination of the two enzyme inhibitors. Exogenous AA caused amylase release in a concentration-dependent manner. Eicosatetraynoic acid (a cyclooxygenase and lipoxygenase inhibitor), significantly increased basal and Cch-induced AA release and amylase secretion. RHC 80267 and the PLA2 inhibitors separately and partially suppressed Cch-stimulated amylase secretion, with an additive effect observed when the DAG lipase and the PLA2 inhibitors were combined. A combination of RHC 80267, mepacrine, or aristolochic acid and the phospholipase C (PLC) inhibitor U73122 completely inhibited Cch-stimulated amylase secretion. Finally, the PLA2 activator melittin-stimulated amylase secretion was blocked by the two PLA2 inhibitors. We conclude that exogenous and endogenous AA can induce amylase secretion. Therefore, AA released from either PLC-DAG lipase or PLA2 pathways can be considered an additional and important intracellular mediator of amylase secretion.

Caerulein-stimulated arachidonic acid release in rat pancreatic acini: a diacylglycerol lipase affair

This study was performed to evaluate the effect of caerulein, a cholecystokinin analogue, on arachidonic acid (AA) release in rat pancreatic acini and to determine the cellular mechanism involved. Caerulein did not stimulate phospholipase A2 (PLA2); however, diacylglycerol (DAG) lipase activity was increased. Validity of PLA2 or DAG lipase inhibitors was confirmed by their ability to selectively inhibit PLA2 or DAG lipase activities. Caerulein increased AA release from acini prelabeled with [3H]AA both dose and time dependently. Inhibitors were used to evaluate the involvement of different signaling pathways. Mepacrine and aristolochic acid, two PLA2 inhibitors, did not inhibit caerulein-induced AA release, whereas the DAG lipase inhibitor RHC-80267 did. The phospholipase C (PLC) inhibitor U-73122 totally inhibited caerulein-induced AA release, whereas the phospholipase D (PLD) inhibitor wortmannin had no effect. Our data indicate that caerulein-induced AA release results from the combined action of PLC and DAG lipase without PLA2 or PLD activation.

Basic fibroblast growth factor-stimulated arachidonic acid release in rat pancreatic acini: sequential action of tyrosine kinase, phospholipase C, protein kinase C and diacylglycerol lipase

This study was performed to evaluate the effect of human recombinant basic fibroblast growth factor on arachidonic acid release from rat pancreatic acini and to determine the cellular mechanism involved. From enzymatic assays, basic fibroblast growth factor did not significantly stimulate phospholipase A2 activity, whereas it significantly increased diacylglycerol lipase activity. Validity of phospholipase A2 or diacylglycerol lipase inhibitors was confirmed by their ability to inhibit phospholipase A2 or diacylglycerol lipase activities. Basic fibroblast growth factor increased intracellular accumulation and extracellular release of arachidonic acid from metabolically labelled acinar cells in a concentration- and time-dependent manner. This effect was maximal with 50 pM basic fibroblast growth factor and became significant after a 5-min incubation period. The protein tyrosine kinase inhibitor, 0.5 mM genistein, inhibited arachidonic acid release in basic fibroblast growth factor-stimulated acini, whereas 100 microM vanadate, a protein tyrosine phosphatase inhibitor, enhanced arachidonic acid release. Two phospholipase A2 inhibitors, mepacrine and aristolochic acid, failed to attenuate basic fibroblast growth factor-stimulated arachidonic acid release. A diacylglycerol lipase inhibitor RHC 80267 at 150 microM and 50 microM completely inhibited 50 pM basic fibroblast growth factor-induced intracellular accumulation and extracellular release of arachidonic acid, respectively. Furthermore, basic fibroblast growth factor stimulated arachidonic acid release was also inhibited by 10 microM U73122 and by 100 nM staurosporine, phospholipase C and protein kinase C respective inhibitors. Wortmannin, an inhibitor of basic fibroblast growth factor-stimulated phospholipase D, did not affect arachidonic acid release. 100 nM 4 beta-phorbol 12-myristate 13-acetate also increased arachidonic acid release, an effect also inhibited by staurosporine. Taken together, these data demonstrate activation of diacylglycerol lipase and arachidonic acid release in pancreatic acini upon stimulation by basic fibroblast growth factor, and strongly indicate that arachidonic acid release in response to basic fibroblast growth factor depends upon the sequential action of tyrosine kinase, phospholipase C, protein kinase C and diacylglycerol lipase but not from phospholipase A2 not phospholipase D activation.

Dual pathways for carbamylcholine-stimulated arachidonic acid release in rat pancreatic acini

Recent studies suggested the involvement of arachidonic acid in the mediation of pancreatic amylase release. However, an effect of carbamylcholine on arachidonic acid release has not yet been reported in the exocrine pancreas. This study was performed to evaluate the effect of carbamylcholine on arachidonic acid release and determine the underlying intracellular mechanisms. From enzymatic assays, phospholipase A(2) and diacylglycerol lipase were activated by carbamylcholine and these activations were inhibited by the phospholipase A(2) inhibitors, mepacrine and aristolochic acid, and by the diacylglycerol lipase inhibitor RHC 80267. Carbamylcholine also increased arachidonic acid release in a concentration-dependent manner. Both phospholipase A(2) and diacylglycerol inhibitors partially inhibited carbamylcholine-stimulated arachidonic acid release. The phospholipase C inhibitor U73122 and the protein kinase C inhibitor staurosporine also caused partial inhibition. Arachidonic acid release by carbamylcholine was suppressed by the simultaneous addition of RHC 80267 with either phospholipase A(2) inhibitors. Our data demonstrate that phospholipase A(2) and diacylglycerol lipase are activated and arachidonic acid is released in pancreatic acini by carbamylcholine. Dual pathways are responsible for carbamylcholine-induced arachidonic acid release. One such pathway involves the sequential action of phospholipase C, protein kinase C and diacylglycerol lipase, whereas the other involves phospholipase A(2) activation.