Chagasic cardiomyopathy is caused by Trypanosoma cruzi infection, and it affects ~7 million individuals on the American continent. Poly(ADP-ribose) polymerase 1 (PARP1) is a nuclear DNA repair enzyme. In this study, we demonstrate that PARP1 tends to be localized to mitochondria in chagasic myocardium. The mtPARP1 was bound to mitochondrial DNA polymerase gamma (Pol ?) that is essential for mtDNA synthesis and repair. Genetic or chemical inhibition of PARP1 was beneficial in improving the mtDNA content, and mitochondrial and left ventricular (LV) function in Chagas disease. Our results suggest that mitochondrial transport of PARP1 adversely impacts the mtDNA maintenance by Pol ? replisome, and exacerbates the mitochondrial dysfunction, oxidative stress, and cardiac remodeling in Chagas disease. We propose that small molecules that prevent PARP1 transport to mitochondria or that arrest PARP1 effects on Pol ? activity will be beneficial in preserving the mitochondrial health and LV function in chronic cardiomyopathy of chagasic (and potentially other) etiologies.
AveXis’s gene therapy is meant to be a one-time treatment, infused into a vein during a 60-minute procedure. It uses an engineered virus to deliver healthy copies of the SMN1 gene to cells throughout the body. Once there, the new gene starts making a protein that’s essential for the survival of motor neurons.
If you wait, however, “the children have limited motor neurons for the gene therapy to get into and work effectively,” says Sukumar Nagendran, AveXis’s chief medical officer.
On average, the 15 children in the AveXis trial received the gene therapy four months after birth. They all responded, but Nagendran says two children who got it within the first two months of life had the most dramatic improvement; they’re now able to walk independently.
In April, AveXis began a new study, this time treating babies immediately after birth. The results will be able to tell researchers just how much better patients fare when they get the drug as newborns.
Other gene therapies may also work better in children before a genetic defect has time to irreparably damage the body. For example, Bluebird Bio is developing one that halted a deadly brain disorder called cerebral adrenoleukodystrophy (ALD), also known as Lorenzo’s Oil disease, in 15 out of 17 children. In a statement provided to MIT Technology Review, the company said outcomes are better when patients are treated before symptoms appear.
On February 8, a national committee that oversees newborn testing voted to recommend that SMA be added to the recommended universal screening panel. The next step is for the secretary of the US Department of Health and Human Services, Alex Azar, to sign off.
Even then, rolling out SMA screening for every newborn isn’t a done deal. A recommendation put forth by the committee is just that—a recommendation. It’s only binding in two states, California and Florida. Other states may choose to adopt the proposal or not...
129S-PARP1tm1Zqw/J (PARP1-/-) mice were crossed with C57BL/6 mice to generate PARP1-/- mice on 129S/BL6 genetic background. PARP1-/- mice were bred with WT mice to generate PARP1+/- mice. All breeding pairs were purchased from Jackson Laboratory (Bar Harbor ME), and a standard PCR was performed to confirm the genotype of WT (PARP1+/+), PARP1+/- and PARP1-/- mice (S1A Fig).
T. cruzi (SylvioX10/4, ATCC 50823) was propagated by in vitro passage in C2C12 cells. The WT, PARP1+/- and PARP1-/- mice (all 129S/BL6 background, 6-weeks-old) were infected with T. cruzi (10,000 trypomastigotes/mouse, intraperitoneal). For some studies, C57BL/6 mice were infected as above, and then mice were given a treatment of 2-(dimethylamino)-N-(6-oxo-5,6-dihydrophenanthridin-2-yl)acetamide hydrochloride (PJ34, Sigma-Aldrich, St Louis MO). PJ34 is a cell-permeable, water-soluble, selective PARP1 inhibitor PJ34 (EC50 = 20 nM) and shown to be ~10,000 times more potent than the prototypical PARP inhibitor, 3-aminobenzamide [20,21]. PJ34 (12.5 mg/kg) was delivered intraperitoneally for three weeks (twice a week) beginning at 45 days’ post-infection (pi) when acute parasitemia was controlled. All mice were harvested at 150 days’ pi corresponding to chronic disease phase. Sera/plasma and tissue samples were stored at 4°C and -80°C, respectively.
Human cardiomyocyte cells (AC16, cat#SCC109, EMD Millipore, Burlington MA) were cultured and maintained in Dulbecco’s modified Eagle’s medium (DMEM)/F-12 medium containing 12.5% fetal bovine serum (FBS). Human cervix epithelial cells (HeLa, ATCC, Manassas VA) were propagated in DMEM media supplemented with Earle's salts, 2 mM L-glutamine and 10% FBS. Cells were infected with T. cruzi (cell: parasite ratio: 1:5) for various studies.