Increased expression of phosphorylated forms of heat‐shock protein‐27 and p38MAPK in macrophage‐rich regions of fibro‐fatty atherosclerotic lesions in the rabbit

Abstract

Summary We aimed to assess the expression and distribution of Hsp27, pHsp27 (Ser82), p38MAPK and p‐p38MAPK in fibro‐fatty atherosclerotic lesions and the myocardium of hypercholesterolaemic rabbits. Male New Zealand white rabbits were fed a high‐cholesterol diet for 18 weeks, maintaining serum cholesterol at approximately 20 mmol/l over this period. Aortic arch and myocardial tissues were analysed by Western blot, immunohistochemistry and double immunofluorescence. Plasma Hsp27 levels were measured by ELISA. There was a significant increase in the expression of monomeric and dimeric forms of Hsp27, together with pHsp27 (Ser82), p38MAPK and p‐p38MAPK in the fibro‐fatty atherosclerotic lesions (P < 0.01; P < 0.05; P < 0.001; and P < 0.001, respectively) and the myocardial tissues (P < 0.001) from the cholesterol‐fed rabbits compared with equivalent tissues from controls when the plasma concentration was low. Immunohistochemical analysis of the fibro‐fatty lesions showed marked increases in Hsp27 and pHsp27 (Ser82) immunoreactivity. Double immunostaining showed intense expression of pHsp27 and p‐p38MAPK in regions that were rich in macrophages, suggesting a close association with these inflammatory cells, whereas, in regions rich in smooth muscle cells, only p‐p38MAPK was found to be strongly expressed. An increased expression of pHsp27 (Ser82) was spatially associated with increased p‐p38MAPK within fibro‐fatty atherosclerotic lesions and was colocalized to regions rich in macrophages. The initial increase in plasma Hsp27 levels may reflect the increase in systemic inflammation and oxidative stress in the early phases of disease. The falling concentrations subsequently may be coincident with the development of the advanced atherosclerotic lesions.

Phosphoproteomic analysis sheds light on intracellular signaling cascades triggered by Formyl-Peptide Receptor 2

“…In addition, in a phospho-proteome analysis of tumors undergoing ischemia, HSP-27 results hyper-phosphorylated at the Ser82 residue suggesting the relevance of this site in ischemia 42 . Furthermore, in atherosclerotic lesions of hypercholesterolaemic rabbits a significant increase of HSP-27(Ser82) phosphorylation and pospho-p38MAPK was observed 43 .…”

“…ANXA1 stimulation of FPR2-expressing cells induces the phosphorylation of p38MAPK/MAPKAP/HSP-27 cascade 43,80 , but in these cells, the phosphorylation of HSP-27 on a Ser82 residue has not been demonstrated. Anti-inflammatory ligands increase the formation of FPR2 homodimers and/or FPR1/FPR2 heterodimers and, in turn, the release of anti-inflammatory cytokines 43 . Since CaLu-6 cells don’t express FPR1 16 , we can exclude FPR1/FPR2, but not FPR2/FPR3 heterodimerization.…”

“…Anti-inflammatory agonists enhance the formation of FPR2 homodimers and the release of inflammation-resolving cytokines, while inflammatory ligands, such as SAA, do not cause receptor homodimerization. Heterodimers of FPR2 with other members of the FPR family can transduce proapoptotic signals 43 . We stimulated CaLu-6 cells with two anti-inflammatory agonists and, in western blot experiments we observed that ANXA1 and LXA4 induce HSP-27(Ser82), OSR1(Ser339), Rb(Ser608), and MARCKS(Ser170) phosphorylation, which was prevented by PTX and WRW4 (Figs.…”

Role of p38 MAPK in Atherosclerosis and Aortic Valve Sclerosis

“…Importantly, the uptake of mLDL seems to be required for p38 MAPK activation and foam cell formation in macrophages [93]. Activation of the p38 MAPK pathway has been demonstrated in macrophages associated with atherosclerotic plaques via immunohistochemistry in patient-derived tissues [94] as well as in animal models [95]. Several in vitro studies have investigated the biological consequences of p38 MAPK activation in atherosclerosis-associated macrophages.…”

4‐Phenylbutyrate protects against atherosclerotic lesion growth by increasing the expression of HSP25 in macrophages and in the circulation of Apoe −/− mice

“…HSP27, a member of the small HSP family, has several reported functions that include protein chaperone activity, modulation of apoptosis, and stabilization of actin filaments (44). We and others have recently described the emerging role of HSP27 in CVD and atherosclerosis (13,17,18,32,45). Low serum HSP27 levels were associated with coronary artery disease and were prognostic of adverse events in patients undergoing coronary or computed tomography angiography (18).…”