Protective role of clusterin in preserving endothelial function in AL amyloidosis

Abstract

Misfolded immunoglobulin light chain proteins (LC) in light chain amyloidosis (AL) are toxic to vascular tissues. We tested the hypothesis that chaperone protein clusterin preserves endothelial function and cell survival during LC exposure. Methods LC (20 μg/mL) were given to human aortic endothelial cells (EC) for 24-hours and clusterin protein/gene expression and secretion were measured. DNA fragmentation was measured with/without recombinant clusterin (Clu, 300 ng/mL). Adipose arterioles (non-AL subjects) were tested for dilator responses to acetylcholine/papaverine at baseline and after 1-hour of LC±Clu. Results LC reduced EC clusterin secretion, protein and gene expression while increasing DNA fragmentation. Clu attenuated LC-induced DNA fragmentation and restored dilator response to acetylcholine (logEC50: control −7.05±0.2, LC+Clu −6.53±0.4, LC −4.28±0.7, p<0.05 vs. control, LC+Clu). Conclusions LC induced endothelial cell death and dysfunction while reducing clusterin protein/gene expression and secretion. Exogenous clusterin attenuated LC toxicity. This represents a new pathobiologic mechanism and therapeutic target for AL amyloidosis.

Adipose and leptomeningeal arteriole endothelial dysfunction induced by β-amyloid peptide: A practical human model to study Alzheimer's disease vasculopathy

“…This is consistent with previous reports that Aβ peptides including Aβ1-42 induce oxidative stress leading to neurotoxicity (Butterfield, 2002), although a prior report suggested that antioxidant treatment may not reverse Aβ neuronal toxicity (Pike et al, 1997) unlike our findings on human vascular tissue. The effects of Aβ shown in this study are similar to the endothelial dysfunction and oxidative/nitrative stress induced by immunoglobulin light chain amyloid proteins (Franco et al, 2012; Migrino et al, 2011), further bolstering the concept that misfolded amyloidogenic proteins, despite varying amino acid compositions, share common toxic pathophysiology possibly triggered by abnormal protein folding (Pastor et al, 2008; Schubert et al, 1995). …”

“…Living subject adipose arterioles were isolated, cannulated and pressurized to 60 mm Hg similar to previous protocol (Franco et al, 2012; Migrino et al, 2011; Truran et al, 2014). Baseline (control) dilator response was measured by videomicrometer after preconstriction with endothelin-1 followed by administration of acetylcholine (for endothelium-dependent dilation, 10 −9 -10 −4 M) and papaverine (for smooth muscle-dependent dilation, 10 −4 M), similar to methods validated by other investigators (Dharmashankar et al, 2012; Kizhakekuttu et al, 2012; Suboc et al, 2013).…”

Nanoliposomes protect against AL amyloid light chain protein-induced endothelial injury

“…We showed that soluble prefibrillar LC induce microvascular dysfunction in ex-vivo human adipose and coronary arterioles (Franco et al, 2012, Migrino et al, 2010, Migrino et al, 2011), consistent with clinical observations of endothelial dysfunction in early (Berghoff et al, 2003) and established disease (Modesto et al, 2007). Chemotherapy±autologous stem cell transplantation to eradicate the plasma cells is the only treatment available but it is associated with high treatment related mortality and cannot be given in many patients with advanced disease (Dispenzieri et al, 2004).…”

Nanoliposomes protect against human arteriole endothelial dysfunction induced by β-amyloid peptide

“…2 Recently, we showed that ex-vivo human leptomeningeal arterioles acutely exposed to soluble b-amyloid peptide 1-42 (Ab42), a major peptide implicated in AD, demonstrate endothelial dysfunction, and that this effect was similar in human abdominal subcutaneous adipose arterioles. 3 We showed similar induction of human arteriole endothelial dysfunction with exposure to light chain proteins derived from patients with AL amyloidosis, [4][5][6] suggesting common vascular toxicity among amyloidogenic proteins despite differences in amino acid composition. When nanoliposomes of less than 100 nM size composed of phospholipids phosphatidylcholine, cholesterol and phosphatidic acid (NLPA) were cotreated with amyloidogenic light chains, endothelial dysfunction was reversed and the b-sheet structure of the light chain protein was altered.…”