👤 Ljiljana Popović

Familial hypercholesterolemia (FH) is characterised by elevated low-density lipoprotein cholesterol (LDL-C) levels and an increased risk of premature cardiovascular disease. The present study aimed to investigate the genetic background, associated biochemical profiles, clinical manifestations, and therapeutic response in patients with clinically suspected FH in Serbia. A total of 101 patients with clinically suspected FH were recruited from the Clinic for Endocrinology, Diabetes and Metabolic Diseases in Serbia between 2015 and 2023. Clinical diagnosis was established using the Dutch Lipid Clinic Network (DLCN) criteria. Genetic profiles of all patients were previously determined using next-generation sequencing. Fasting serum lipids, apolipoprotein A-I [ApoA-I], apolipoprotein B [ApoB], and lipoprotein(a) (Lp(a)) were measured enzymatically. Levels of serum lipids were compared between genetically FH-positive (carriers of variants in LDLR, APOB, PCSK9 and LDLRAP1 genes) and FH-negative patients. Therapeutic response was assessed by achieving the LDL-C target level. Statistical analyses were conducted in SPSS (version 30.0). Genetically confirmed FH patients exhibited significantly higher levels of ApoB (p=0.001) compared with variant-negative individuals, while ApoA-I (p=0.413) and Lp(a) (p=0.421) levels did not differ significantly between groups. Patients with pathogenic FH-associated variants were less likely to reach target LDL-C levels after therapy than those without identified variants. This study demonstrates biochemical diversity in familial hypercholesterolemia associated with genetic background in the Serbian population. Pathogenic FH mutations were associated with higher ApoB levels, underscoring the importance of combining genetic testing with lipid profiling for precise diagnosis and management. Show less

Sitagliptin, an anti-diabetic drug, is a dipeptidyl peptidase (DPP)-4/CD26 inhibitor with additional anti-inflammatory and immunomodulatory properties. In this study, we investigated for the first time the effect of sitagliptin on the differentiation and functions of human dendritic cells generated from monocytes (MoDCs) for 4 days using the standard GM-CSF/IL-4 procedure. LPS/IFN-γ treatment for an additional 24 h was used for maturation induction of MoDCs. Sitagliptin was added at the highest non-cytotoxic concentration (500 µg/mL) either at the beginning (sita 0d protocol) or after MoDC differentiation (sita 4d protocol). Sitagliptin impaired differentiation and maturation of MoDCs as judged with the lower expression of CD40, CD83, CD86, NLRP3, and HLA-DR, retention of CD14 expression, and inhibited production of IL-β, IL-12p70, IL-23, and IL-27. In contrast, the expression of CD26, tolerogenic DC markers (ILT4 and IDO1), and production of immunoregulatory cytokines (IL-10 and TGF-β) were increased. Generally, the sita 0d protocol was more efficient. Sitagliptin-treated MoDCs were poorer allostimulators of T-cells in MoDC/T-cell co-culture and inhibited Th1 and Th17 but augmented Th2 and Treg responses. Tolerogenic properties of sitagliptin-treated MoDCs were additionally confirmed by an increased frequency of CD4+CD25+CD127- FoxP3+ Tregs and Tr1 cells (CD4+IL-10+FoxP3-) in MoDC/T-cell co-culture. The differentiation of IL-10+ and TGF-β+ Tregs depended on the sitagliptin protocol used. A Western blot analysis showed that sitagliptin inhibited p65 expression of NF-kB and p38MAPK during the maturation of MoDCs. In conclusion, sitagliptin induces differentiation of tolerogenic DCs, and the effect is important when considering sitagliptin for treating autoimmune diseases and allotransplant rejection. Show less