LOX-1 dependent overexpression of immunoglobulins in cardiomyocytes in response to angiotensin II

LOX-1, a cell surface lectin-like receptor, is upregulated by oxidized low-density lipoprotein (ox-LDL) and angiotensin II (Ang II), and plays an important role in host defense. The specific C-type lectin domain on LOX-1 is essential for ox-LDL. binding and internalization, generation of oxidant species and eliciting immune response. Here, we show that LOX-1 deletion alters genes that relate to immune response. Microarray (and qPCR) analysis of cardiac tissues showed downregulated expression of several immunoglobulins (Igk-V8, Igk-C, Igh-6, W, Ighg, Igh, and Igl-VI) in the LOX-1 Knockout (KO) mice [p < 0.05 vs. the wild-type (WT) mice]. The expression of these immunoglobulins Was upregulated several-fold in the LOX-1 KO mice hearts when these mice were infused with Ang II (p < 0.05, vs. WT mice). Importantly, cultured Mouse HL-1 cardiomyocytes expressed these immunoglobulins, and pretreatment of cardiomyocytes with a specific anti-LOX-1 antibody enhanced the generation Of immunoglobulins upon Subsequent exposure to Ang II. These observations mirrored the data obtained from WT and LOX-1 KO mice hearts in the resting state and following Ang II infusion. This Study provides first set of data on immunoglobulin expression in cardiac tissues of WT and LOX-1 KO mice and in cultured HL-1 cardiomyocytes, and demonstrates that LOX-1 inactivation leads to upregulation of immunoglobulins in cardiomyocytes upon challenge with Ang II. (c) 2009 Published by Elsevier Inc.