👤 Dimas Echeverria

Chemically modified small interfering RNAs (siRNAs) are a promising drug class that silences disease-causing genes via mRNA degradation. Both siRNA-specific features (e.g. sequence, modification pattern, and structure) and target mRNA-specific factors contribute to observed efficacy. Systematically defining the relative contributions of siRNA sequence, structure, and modification pattern versus the native context of the target mRNA is necessary to inform design considerations and facilitate the widespread application of this therapeutic platform. To address this, we synthesized a panel of ∼1260 differentially modified siRNAs and evaluated their silencing efficiency against therapeutically relevant mRNAs (APP, BACE1, MAPT, and SNCA) using both reporter-based and native expression assays. Our results demonstrate that the siRNA modification pattern (e.g. level of 2'-O-methyl content) significantly impacts efficacy, while structural features (e.g. symmetric versus asymmetric configurations) do not. Furthermore, we observed substantial differences in the number of effective siRNAs identified per target. These target-specific differences in hit rates are largely mitigated when efficacy is tested in the context of a reporter assay, confirming that native mRNA-specific features influence siRNA performance. Key target-specific factors, including exon usage, polyadenylation site selection, and ribosomal occupancy, partially explained efficacy variability. These insights led to a proposed framework of parameters for optimizing therapeutic siRNA design. Show less

HIV-infected patients treated with highly active antiretroviral therapy (HAART) may be predisposed to a lipid profile, associated with increased cardiovascular risk, derived from having high triglycerides (TG) and low high-density lipoprotein cholesterol (HDLc) levels. We propose that genetic variability leaves some HIV-infected patients more predisposed to this lipid profile than others. We performed a cross-sectional, observational study including 321 antiretroviral-treated HIV-infected patients classified as normolipidemic (n=173) or presenting with high TG (≥1.7 mmol/liter) and low HDLc [<1.02 (men) or 1.28 mmol/liter (women)] (n=148) to investigate the impact of 13 polymorphisms of 9 genes affecting lipid metabolism (APOA5, APOC3, LPL, CETP, HL, MTP, APOE, LRP5, and VLDLR genes). The polymorphism rs328 in LPL was 40% significantly more frequent in normolipidemics (p=0.018), and in the same group, polymorphisms rs708272 in CETP and rs1800588 in HL were 10% significantly more frequent (p=0.037 for both polymorphisms). Patients who presented a combination of one to six alleles from these polymorphisms had 10% increased HDLc levels [1.13 (0.40) vs. 1.24 (0.23) mmol/liter, p=0.002] and a trend toward lower triglycerides [2.23 (2.34) vs. 1.89 (1.24) mmol/liter] and lower remnant-like particle cholesterol (RLPc) [16.41 (11.42) vs. 12.99 (11.69) mmol/liter]. This effect was dependent on the number of protective alleles and independent of the regimen administered. Polymorphisms in LPL, CETP, and HL protect HIV-infected patients from developing the dyslipidemia derived from high TG and low HDLc levels in a dose-dependent manner. Show less

Several studies have reported associations between lipid parameters and clinical progression of HIV infection. We performed a cross-sectional study including 468 antiretroviral-treated HIV-infected patients to investigate the impact of 13 polymorphisms of 9 genes affecting lipid metabolism and CD4 and CD8-T cell levels. Polymorphisms were identified in genes selected for their role in the development of atherogenic dyslipidemia, defined as triglycerides ⩾1.7mmol/L and high-density lipoprotein cholesterol (HDLc) <1.02 in women or 1.28mmol/L in men. Lipid and lipoprotein parameters were determined in all participants, as well as CD4 and CD8 T-cell counts. ANOVA was performed to compare the mean values of lipid and CD4 and CD8 T-cell count data. A Bonferroni correction for multiple comparisons was applied. 468 patients were included, 148 of them had a diagnosis of atherogenic dyslipidemia. The polymorphism rs3135506 in APOA5 was associated with a 9% increase in triglycerides (p=0.002), 10% and 21% decrease in HDLc (p=0.005), and CD4 T-cell count (p=0.024), respectively. APOA5 rs662799, was associated with a 19% increase in CD8 T-cell count (p=0.002). Carriers of LPL rs328 in the dyslipidemic group presented 11% higher levels of HDLc (p=0.015) and 14% higher levels of CD4 cells (p=0.038). In conclusion, polymorphisms in genes associated to the development of atherogenic dyslipidemia, especially variants in APOA5 gene (rs3135506 and rs662799), can influence the circulating CD4 T-cell levels in chronically HIV-infected patients. These data support previous reports on the effect of lipid metabolism on immunologic parameters in HIV+ individuals on antiretroviral therapy. Show less