Systemic sclerosis and primary biliary cholangitis share an antibody population with identical specificity

Anti-centromere (ACA) and antimitochondrial antibodies (AMA) are specific for limited-cutaneous systemic sclerosis (lcSSc) and primary biliary cholangitis (PBC), respectively, and can coexist in up to 25 and 30% of SSc and PBC patients. Here, we evaluated whether anti-centromeric protein A (CENP-A) antibodies cross-react with mitochondrial antigens. To this end, sera from two lcSSc patients (pt1 and pt4), one of them (pt4) also affected by PBC, were used as the source of ACA, previously shown to recognize different groups of amino acids (motifs) in the CENP-A region spanning amino acids 1-17 (Ap1-17). Pt1 and pt4 Ap1-17-specific IgG were purified by affinity-chromatography on insolubilized Ap1-17-peptide column and tested by western blotting with nuclear and cytoplasmic protein extract from HeLa cells. Immunoreactive proteins were identified by mass spectrometry and validated by immunodot. The results showed that affinity-purified SSc/PBC pt4 anti-Ap1-17 and not SSc pt1 anti-Ap1-17 Ab, specifically cross-reacted with the E2 component of the mitochondrial pyruvate dehydrogenase complex (PDC-E2), the major mitochondrial autoantigen in PBC. Sequence homology analysis indicated that the motif A-x-x-P-x-A-P recognized by pt4 anti-Ap1-17 IgG and shared by CENP-A and PDC-E2, is also expressed by some members of the Human Herpesvirus family, suggesting that they may trigger the production of these cross-reacting antibodies.

Dual Effect of Prussian Blue Nanoparticles on Aβ40 Aggregation: β-Sheet Fibril Reduction and Copper Dyshomeostasis Regulation

Alzheimer's disease (AD), affecting almost 50 million individuals worldwide, is currently the first cause of dementia. Despite the tremendous research efforts in the last decade, only four supportive or palliative drugs, namely, acetylcholinesterase (AChE) inhibitors donepezil, galantamine, and rivastigmine and the glutamate NMDA receptor antagonist memantine, are currently available. New therapeutic strategies are becoming prominent, such as the direct inhibition of amyloid formation or the regulation of metal homeostasis. In the present report, the potential use of Prussian blue (PB), a drug that is in the World Health Organization Model List of Essential Medicines, in AD treatment is demonstrated. Both in vitro and in cellulo studies indeed suggest that PB nanoparticles (PBNPs) are capable of reducing the formation of typical amyloid-β fibers (detected by thioflavin T fluorescence) and restoring the usual amyloid fibrillation pathway via chelation/sequestration of copper, which is found in high concentrations in senile plaques.