Group III secreted phospholipase A2 transgenic mice spontaneously develop inflammation

Area of Science:

• Biochemistry and Molecular Biology
• Immunology and Inflammation Research
• Dermatology and Pathology

Background:

• Group III secretory phospholipase A2 (sPLA2) is an atypical enzyme homologous to bee venom PLA2, distinct from other mammalian sPLA2s.
• The physiological role and inflammatory potential of endogenous group III sPLA2 (PLA2G3) in mammals remain largely uncharacterized.

Purpose of the Study:

• To investigate the in vivo expression and function of endogenous group III sPLA2 (PLA2G3) in mammalian skin.
• To determine the consequences of PLA2G3 overexpression on skin and systemic inflammation in a transgenic mouse model.

Main Methods:

• Generation and characterization of transgenic (Tg) mice overexpressing human PLA2G3.
• Histopathological analysis of skin and other organs in Pla2g3-Tg mice.
• Assessment of inflammatory markers, including cytokine and chemokine levels, and immune cell infiltration.

Main Results:

• Endogenous PLA2G3 is expressed in mouse skin.
• Pla2g3-Tg mice spontaneously developed severe dermatitis, characterized by hyperkeratosis, acanthosis, parakeratosis, erosion, ulceration, and sebaceous gland hyperplasia.
• Dermatitis was associated with neutrophil and macrophage infiltration, elevated pro-inflammatory mediators (cytokines, chemokines, PGE2), and systemic inflammatory manifestations including splenomegaly and increased IgG1.

Conclusions:

• Overexpression of mammalian group III sPLA2 (PLA2G3) is sufficient to induce spontaneous skin inflammation and dermatitis in mice.
• These findings establish a direct link between PLA2G3 and the development of inflammatory conditions.
• The study provides the first evidence of spontaneous inflammation resulting from transgenic overexpression of a mammalian sPLA2.