Dataset Information

Lung mast cells are a source of secreted phospholipases A2.

ABSTRACT:

Background

Secreted phospholipases A(2) (sPLA(2)s) are released in plasma and other biologic fluids of patients with inflammatory, autoimmune, and allergic diseases.

Objective

We sought to evaluate sPLA(2) activity in the bronchoalveolar lavage fluid (BALF) of asthmatic patients and to examine the expression and release of sPLA(2)s from primary human lung mast cells (HLMCs).

Methods

sPLA(2) activity was measured in BALF and supernatants of either unstimulated or anti-IgE-activated HLMCs as hydrolysis of oleic acid from radiolabeled Escherichia coli membranes. Expression of sPLA(2)s was examined by using RT-PCR. The release of cysteinyl leukotriene (LT) C(4) was measured by means of enzyme immunoassay.

Results

Phospholipase A(2) (PLA(2)) activity was higher in the BALF of asthmatic patients than in the control group. BALF PLA(2) activity was blocked by the sPLA(2) inhibitors dithiothreitol and Me-Indoxam but not by the cytosolic PLA(2) inhibitor AZ-1. HLMCs spontaneously released a PLA(2) activity that was increased on stimulation with anti-IgE. This PLA(2) activity was blocked by dithiothreitol and Me-Indoxam but not by AZ-1. HLMCs constitutively express mRNA for group IB, IIA, IID, IIE, IIF, III, V, X, XIIA, and XIIB sPLA(2)s. Anti-IgE did not modify the expression of sPLA(2)s. The cell-impermeable inhibitor Me-Indoxam significantly reduced (up to 40%) the production of LTC(4) from anti-IgE-stimulated HLMCs.

Conclusions

sPLA(2) activity is increased in the airways of asthmatic patients. HLMCs express multiple sPLA(2)s and release 1 or more of them when activated by anti-IgE. The sPLA(2)s released by mast cells contribute to LTC(4) production by acting in an autocrine fashion. Mast cells can be a source of sPLA(2)s in the airways of asthmatic patients.

SUBMITTER: Triggiani M

PROVIDER: S-EPMC2788562 | biostudies-literature | 2009 Sep

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Lung mast cells are a source of secreted phospholipases A2.

Triggiani Massimo M Giannattasio Giorgio G Calabrese Cecilia C Loffredo Stefania S Granata Francescopaolo F Fiorello Alfonso A Santini Mario M Gelb Michael H MH Marone Gianni G

The Journal of allergy and clinical immunology 20090709 3

<h4>Background</h4>Secreted phospholipases A(2) (sPLA(2)s) are released in plasma and other biologic fluids of patients with inflammatory, autoimmune, and allergic diseases.<h4>Objective</h4>We sought to evaluate sPLA(2) activity in the bronchoalveolar lavage fluid (BALF) of asthmatic patients and to examine the expression and release of sPLA(2)s from primary human lung mast cells (HLMCs).<h4>Methods</h4>sPLA(2) activity was measured in BALF and supernatants of either unstimulated or anti-IgE-ac ...[more]

PMID: 19541351

Similar Datasets

Project description:We have previously shown that secreted phospholipases A2 (sPLA2s) from animal venoms inhibit the in vitro development of Plasmodium falciparum, the agent of malaria. In addition, the inflammatory-type human group IIA (hGIIA) sPLA2 circulates at high levels in the serum of malaria patients. However, the role of the different human sPLA2s in host defense against P. falciparum has not been investigated. We show here that 4 out of 10 human sPLA2s, namely, hGX, hGIIF, hGIII, and hGV, exhibit potent in vitro anti-Plasmodium properties with half-maximal inhibitory concentrations (IC50s) of 2.9 ± 2.4, 10.7 ± 2.1, 16.5 ± 9.7, and 94.2 ± 41.9 nM, respectively. Other human sPLA2s, including hGIIA, are inactive. The inhibition is dependent on sPLA2 catalytic activity and primarily due to hydrolysis of plasma lipoproteins from the parasite culture. Accordingly, purified lipoproteins that have been prehydrolyzed by hGX, hGIIF, hGIII, and hGV are more toxic to P. falciparum than native lipoproteins. However, the total enzymatic activities of human sPLA2s on purified lipoproteins or plasma did not reflect their inhibitory activities on P. falciparum. For instance, hGIIF is 9-fold more toxic than hGV but releases a lower quantity of nonesterified fatty acids (NEFAs). Lipidomic analyses of released NEFAs from lipoproteins demonstrate that sPLA2s with anti-Plasmodium properties are those that release polyunsaturated fatty acids (PUFAs), with hGIIF being the most selective enzyme. NEFAs purified from lipoproteins hydrolyzed by hGIIF were more potent at inhibiting P. falciparum than those from hGV, and PUFA-enriched liposomes hydrolyzed by sPLA2s were highly toxic, demonstrating the critical role of PUFAs. The selectivity of sPLA2s toward low- and high-density (LDL and HDL, respectively) lipoproteins and their ability to directly attack parasitized erythrocytes further explain their anti-Plasmodium activity. Together, our findings indicate that 4 human sPLA2s are active against P. falciparum in vitro and pave the way to future investigations on their in vivo contribution in malaria pathophysiology.

Dataset Information

Lung mast cells are a source of secreted phospholipases A2.

Background

Objective

Methods

Results

Conclusions

Publications

Lung mast cells are a source of secreted phospholipases A2.

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