Suramin inhibits macrophage activation by human group IIA phospholipase A2, but does not affect bactericidal activity of the enzyme.
OBJECTIVE
Suramin is a polysulphonated napthylurea antiprotozoal and anthelminitic drug, which also presents inhibitory activity against a broad range of enzymes. Here we evaluate the effect of suramin on the hydrolytic and biological activities of secreted human group IIA phospholipase A(2) (hsPLA(2)GIIA).


METHODS
The hsPLA(2)GIIA was expressed in E. coli, and refolded from inclusion bodies. The hydrolytic activity of the recombinant enzyme was measured using mixed dioleoylphosphatidylcholine/dioleoylphosphatidylglycerol (DOPC/DOPG) liposomes. The activation of macrophage cell line RAW 264.7 by hsPLA(2) GIIA was monitored by NO release, and bactericidal activity against Micrococcus luteus was evaluated by colony counting and by flow cytometry using the fluorescent probe Sytox Green.


RESULTS
The hydrolytic activity of the hsPLA(2) GIIA was inhibited by a concentration of 100 nM suramin and the activation of macrophages by hsPLA(2) GIIA was abolished at protein/suramin molar ratios where the hydrolytic activity of the enzyme was inhibited. In contrast, both the bactericidal activity of hsPLA(2) GIIA against Micrococcus luteus and permeabilization of the bacterial inner membrane were unaffected by suramin concentrations up to 50 microM.


CONCLUSIONS
These results demonstrate that suramin selectively inhibits the activity of the hsPLA(2) GIIA against macrophages, whilst leaving the anti-bacterial function unchanged.
Aragão
E A
EA
Department of Chemistry, FFCLRP-USP, Universidade de São Paulo, São Paulo, Brazil.
Chioato
L
L
Ferreira
T L
TL
de Medeiros
A I
AI
Secatto
A
A
Faccioli
L H
LH
Ward
R J
RJ
D000818:Animals; D000969:Antinematodal Agents / Q000737:chemistry / Q000494:pharmacology*; D002460:Cell Line; D054501:Group II Phospholipases A2 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D002479:Inclusion Bodies / Q000201:enzymology; D008262:Macrophage Activation / Q000187:drug effects* / Q000502:physiology; D008264:Macrophages / Q000166:cytology / Q000502:physiology; D008826:Microbial Sensitivity Tests; D015394:Molecular Structure; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013498:Suramin / Q000737:chemistry / Q000494:pharmacology*
D000969:Antinematodal Agents; D011994:Recombinant Proteins; D013498:Suramin; D054501:Group II Phospholipases A2; C516287:PLA2G2A protein, human