Antibacterial actions of secreted phospholipases A2. Review

Lysosomal phospholipase A2: A novel player in host immunity to Mycobacterium tuberculosis

“…Enzymes of the phospholipase A 2 (PLA 2 ) family play multiCorrespondence: Prof. Ulrich E. Schaible e-mail: uschaible@fz-borstel.de ple roles in lung infection and inflammation [2]. Apart from being involved in the generation of bioactive lipids such as eicosanoids, which are involved in inflammation by regulating cytokine and chemokine responses, direct bactericidal activity due to hydrolysis of bacterial-membrane phospholipids has also been shown for secretory PLA 2 (sPLA 2 ) [2,3]. Despite the essential function of lysosomes for membrane degradation, which is a primary function of phagocytes, only a few responsible enzymes were identified so far.…”

Pseudomonas aeruginosa eradicates Staphylococcus aureus by manipulating the host immunity

“…Among mammalian PLA2s, type-IIA-secreted PLA2 (sPLA2-IIA) has been shown to exert a potent bactericidal effect 14,19 . Grampositive bacteria are much more sensitive to sPLA2-IIA than Gram-negative bacteria due to higher affinity of sPLA2-IIA to the cell walls of Gram-positive bacteria 14,17 . Selective hydrolysis of bacterial membrane phospholipids represents the critical step of bactericidal action of sPLA2-IIA 20 .…”

“…According to our hypothesis, the levels of this molecule would increase with age of CF patients and PA infection leading to progressive elimination of SA from airways. Among the host molecules endowed with antibacterial properties, antimicrobial peptides (AMPs) play a key role in natural host defense toward invading pathogens [14][15][16] . AMPs are ubiquitous, gene-encoded natural 'antibiotics' including cationic peptides, defensins and some secreted phospholipases A2 (sPLA2s) 14,17 .…”

“…Given that sPLA2-IIA is known to exert potent bactericidal effects against Gram-positive bacteria 14,17 , we examined at first the presence of this enzyme in the expectorations from CF patients. It is not possible to obtain sputum from healthy individuals.…”

Mechanisms of the innate immunity in the respiratory system

“…lipopolysaccharide (LPS), therefore an increased expression of sPLA2 is found mainly in areas of intense inflammatory reaction [23,24]. The main activity of sPLA2 concerns the generation of bioactive eicosanoids, stimulation of chemokines and cytokines expression, however, the direct bactericidal activity of sPLA2 against various bacteria was also reported [25].…”