Atherosclerosis

Proprotein convertases in human atherosclerotic plaques: the overexpression of FURIN and its substrate cytokines BAFF and APRIL

BACKGROUND

Proprotein convertase subtilisin/kexin (PCSK) enzymes cleave proproteins into mature end products. Previously, MBTPS1 and PCSK9 have been shown to regulate cholesterol metabolism and LDL receptor recycling, whereas FURIN and PCSK5 have been suggested to inactivate lipases and regulate inflammation in atherosclerosis. Here, we systematically analyzed the expression of PCSKs and their targets in advanced atherosclerotic plaques.

METHODS AND RESULTS

Microarray and quantitative real-time PCR experiments showed that FURIN (42.86 median fold, p = 2.1e-8), but no other PCSK, is universally overexpressed in the plaques of different vascular regions. The mRNA expression screen of PCSK target proteins in plaques identified many known factors, but it also identified the significant upregulation of the previously overlooked furin-processed B cell activating cytokines APRIL (TNFSF13, 2.52 median fold, p = 3.0e-5) and BAFF (TNFSF13B, 2.97 median fold, p = 7.6e-6). The dysregulation of FURIN did not associate with its htSNPs or the previously reported regulatory SNP (-229, rs4932178) in the promoter. Immunohistochemistry experiments showed the upregulation of FURIN in the plaque lymphocytes and macrophages where it was co-expressed with BAFF/TNFSF13B and APRIL/TNFSF13.

CONCLUSIONS

Our data unequivocally show that FURIN is the primary PCSK that is dysregulated in the immune cells of advanced human atherosclerotic plaques, which implies a role for this enzyme in plaque pathology. Therefore, drugs that inhibit FURIN in arteries may modulate the course of this disease.

Differences in the predictive value of tumor necrosis factor-like weak inducer of apoptosis (TWEAK) in advanced ischemic and non-ischemic heart failure

OBJECTIVE

To assess the prognostic value of the pro-apoptotic, but also cell growth-inducing molecule soluble tumor necrosis factor-like weak inducer of apoptosis (sTWEAK) in heart failure (HF).

METHODS

We assayed sTWEAK levels in 351 patients with advanced HF (non-ischemic: 130, ischemic: 221). During a median follow-up of 4.9 years, 195 patients (56%) died.

RESULTS

sTWEAK concentrations were associated with extended survival in patients with non-ischemic (P=0.022), but not with ischemic HF (P=0.82). The inverse association in non-ischemic HF remained significant in a multivariable Cox regression model (P=0.025) with a hazard ratio of 0.40 (95% confidence interval: 0.21-0.77) comparing the third to the first tertile (P=0.007).

CONCLUSION

Low sTWEAK levels independently predict mortality in advanced non-ischemic HF. sTWEAK-induced proliferation of cardiomyocytes may explain its impact on suvival. The different prognostic value of sTWEAK in ischemic and non-ischemic HF may point towards distinct pathogenic pathways determining the course of disease.