BACKGROUND:It has been recognized that hypertriglyceridemia (HTG) is associated with kidney damage. Monogenic and polygenic causes of extreme HTG characterized by severe chylomicronemia (TG > 885 mg/dl or 10 mmol/L) constitute unique models to investigate the potential nephrotoxic effects of sustained and severe exposure to HTG. METHODS:This study had two components: (1) kidney biopsies of three patients with severe chylomicronemia and proteinuria were analyzed; (2) a cross-sectional review of the medical files of two independent cohorts of patients with the Familial Chylomicronemia Syndrome (FCS) or Multifactorial Chylomicronemia Syndrome (MCS) followed in Italy and Canada was performed. Renal involvement was defined by the presence of proteinuria, reduced eGFR (<90 mL/min/1.73 m2), or hyperfiltration (≥105 mL/min/1.73 m2). RESULTS:Histological findings in the three patients with severe chylomicronemia revealed diverse patterns of glomerular injury, including lipid-laden glomerular damage, foam-cell infiltration, all consistent with lipid-associated nephropathy. Among the 84 adults with severe chylomicronemia (38 F CS, 46 MCS), 35 % had a history of proteinuria, 49 % presented eGFR<90 mL/min/1.73 m2, 8 % had eGFR<60 mL/min/1.73 m2, and 41 % showed hyperfiltration. Hypertension and diabetes emerged as independent covariates for proteinuria and reduced eGFR. CONCLUSIONS:These data suggest that severe chylomicronemia due to FCS and MCS is predominantly associated with proteinuria, which might be the possible consequences of lipid-laden glomerular injury. Therefore, renal disease should be included in the list of possible complications of severe chylomicronemia, thus suggesting that renal monitoring have to be considered as part of clinical management of these conditions.

BACKGROUND:The definitive diagnosis of Familial Hypercholesterolemia (FH) relies on the identification of deleterious variants in FH-related genes, but many detected variants are classified as of uncertain significance (VUS). This study aims to evaluate the functional impact of LDLR VUS using an optimized flow cytometry assay in autologous activated CD4+ T lymphocytes. METHODS:Twenty unique LDLR variants were tested. Six known pathogenic variants served as positive controls, while T lymphocytes from normocholesterolemic individuals were used as negative controls. Peripheral blood mononuclear cells were stimulated with CD3/CD28 beads in lipoprotein-deficient serum. LDLR expression, LDL binding, and uptake were quantified by flow cytometry using Bodipy-labeled LDL and expressed as the geometric mean fluorescence intensity ratio between patient and wild-type CD4+ T cells. Following ClinGen FH Expert Panel Specifications guidelines variants were classified as defective if activity was <85% of wild-type in at least one parameter. For a VUS subset, LDLR activity was further tested by site-directed mutagenesis and optical microscopy. RESULTS:At flow cytometry assay, 15 variants (75%) showed deleterious effects in at least one functional LDLR parameter; the others affected expression (n = 5; 35.7%) or binding/expression or binding/uptake (n = 6; 42.8%); only 4 (21.5%) impaired the entire LDLR cycle. Site-directed mutagenesis and/or microscopy of selected variants [c.(-97)G > A, c.367T > C, c.929T > A, c.1007A > G, c.1530_1532del, c.1945C > T, c.2282C > T, c.2479G > A, c.∗34C > T], confirmed impaired LDLR activity, supporting the flow cytometry findings. CONCLUSIONS:This optimized flow cytometry assay provides robust functional assessment of LDLR VUS, improving definitive FH diagnosis and supporting its inclusion in FH diagnostic workflows.

BACKGROUND:Angiopoietin-like protein 3 (ANGPTL3) is a key circulating regulator of triglyceride metabolism and a promising pharmacological target. The physiological consequences of profound ANGPTL3 deficiency can be explored in individuals with inherited loss-of-function (LOF) variants, who show reduced lifetime risk of atherosclerotic cardiovascular disease. METHODS:ApoB48, apoB100 and TG metabolism were investigated in chylomicrons, VLDL1, VLDL2, IDL and LDL in 3 ANGPTL3 LOF homozygotes (undetectable plasma ANGPTL3), 4 LOF heterozygotes (ANGPTL3 45.0 ± 7.4 ng/mL) and 10 matched controls (ANGPTL3 110.5 ± 27.6 ng/mL). Studies were performed under post-prandial conditions to comprehensively characterize TG transport and apoB-containing lipoprotein kinetics. RESULTS:Chylomicron and very-low-density lipoproteins (VLDL) production rates were similar in ANGPTL3-deficient subjects and controls. The defining abnormality in LOF homozygotes was the extremely rapid lipolysis of chylomicrons and VLDL, with circulating residence times of minutes rather than hours and accelerated conversion of VLDL to IDL and LDL. LDL particles in LOF homozygotes were TG-enriched, cholesterol-depleted, metabolically heterogeneous and cleared more rapidly than in controls or LOF heterozygotes. LOF heterozygotes showed a less pronounced increase in chylomicron and VLDL lipolysis, with normal IDL and LDL kinetics. CONCLUSION:Complete loss of ANGPTL3 results in a rapid acceleration of the triglyceride-rich lipoprotein lipolysis pathway and promotes the formation of metabolically and compositionally abnormal LDL with accelerated clearance. These findings provide mechanistic insight into ANGPTL3 deficiency and are directly relevant for the development and safety assessment of ANGPTL3-targeted therapies.

BACKGROUND & AIMS:Lifelong APOB gene inactivation lowers LDL-C and cardiovascular risk, but impairs hepatic lipoprotein export, predisposing to chronic liver disease (CLD). The extent to which common steatogenic factors modulate this risk remains unclear. Moreover, the balance between long-term cardiovascular protection and CLD risk in APOB variant carriers has never been evaluated. METHODS:Using UK Biobank data, we analysed 241 APOB loss-of-function (LoF) carriers and 410 721 non-carriers, stratified by steatogenic risk factors, including age, sex, diabetes, BMI, alcohol intake and the PNPLA3-rs738409 genotype. Associations with transaminase levels, CLD and cardiovascular (ASCVD) outcomes were assessed using Python and R packages. RESULTS:APOB carriers had ~35% lower LDL-C and apoB levels, along with reduced total triglycerides and Lp(a) (all p < 0.001). Baseline ALT and AST were higher in carriers than in non-carriers (Padj = 3.6 × 10-7), particularly among those with obesity (p ≤ 0.003). The prevalence and incidence of CLD were consistently higher in carriers across all risk factor categories (p ≤ 0.01), with the strongest association in those with diabetes and obesity over 15 years of follow-up (Padj = 0.03). In contrast, APOB carriers as a whole had a 57% lower ASCVD risk (Padj = 0.009), with a similar atheroprotective trend across all risk factor categories. This corresponded to an absolute risk reduction of 2.30 ASCVD events/1000 person-years (p = 0.002) and an absolute increase of 3.48 CLD events/1000 person-years (p = 0.003). CONCLUSIONS:Long-term exposure to low LDL-C levels due to APOB LoF variants has opposite consequences, reducing ASCVD risk but increasing CLD risk, especially in the presence of diabetes and obesity. These findings highlight the importance of balancing cardiovascular benefit with hepatic safety when considering apoB-targeting therapies.

The BRAF p.V600E mutation activates the RAS/BRAF/MEK/ERK pathway, leading to cancer cell dedifferentiation and uncontrolled growth. In radioiodine-refractory thyroid cancers, MEK and/or BRAF inhibitors can induce redifferentiation, resensitizing tumors to radioiodine. However, compensatory mechanisms limit this efficacy. We used the SWitchMiner software to identify a small pool of regulatory genes, called switch genes, critically associated with drastic changes in cell phenotypes, using TCGA transcriptomic data from BRAF-mutant papillary thyroid carcinoma and normal thyroid tissues, which highlighted miR-335-5p. Restoring miR-335-5p in thyroid cancer cell lines harboring the BRAF mutation increased expression of thyroid-specific genes and proteins, especially in well-differentiated cell lines, with enhanced sodium-iodide symporter localization and iodine uptake confirmed in organoids. Due to the connection between thyroid-specific and EMT-related genes in the protein-protein interaction network, we examined how miR-335-5p overexpression affects EMT pathway genes that modulate thyroid-specific genes and Kinase Inhibitor (KI) resistance. miR-335-5p inhibited the expression of nearly all analyzed genes in less-differentiated thyroid cell lines. Thus, miR-335-5p may be a viable therapeutic target to restore radioiodine avidity in BRAF-mutant metastatic thyroid cancer and enhance KI treatment redifferentiation.

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in patients with chronic kidney disease (CKD). Quantitative and qualitative changes in plasma lipoprotein profiles are frequently associated with CKD and represent a significant risk factor for CVD in patients with CKD. Guidelines from the European Society of Cardiology and the European Atherosclerosis Society classify CKD as a condition with high or very high cardiovascular risk and set specific low-density lipoprotein cholesterol targets. Conventional lipid-lowering therapies (LLTs), such as statins, ezetimibe, and fibrates, can control CKD-associated dyslipidemia and, to some extent, prevent major atherosclerotic events in patients with CKD, but their use in clinical practice presents challenges because of the potential renal safety concerns. In recent years, novel therapies with the ability to lower both low-density lipoprotein cholesterol and triglycerides have been introduced to the market (e.g., proprotein convertase subtilisin/kexin type 9 inhibitors, bempedoic acid, lomitapide, volanesorsen) to improve our ability to control lipid abnormalities. However, their impact on kidney functionality has not been fully elucidated. The aim of this review was to examine the renal safety profiles of various LLTs, with special reference to novel medications, and to highlight important considerations and guidance for the use of these medications in overt CKD or in patients with some degree of renal function impairment. We underscore the lack of a comprehensive understanding of kidney safety, particularly for novel LLT therapies, and strongly emphasize the importance of future dedicated research to fully assess the safety and efficacy of these agents in patients with kidney abnormalities.

ANGPTL3 and PCSK9 are core proteins involved in lipid metabolism. Literature evidence highlights a potential mutual regulation between them: patients harboring loss-of-function variants in ANGPTL3 show reduced levels of circulating PCSK9. After predicting their interaction using an in-silico model, we verified the direct interaction between ANGPTL3 and PCSK9 through co-immunoprecipitation. The ANGPTL3-PCSK9 complex persisted under fasting conditions and dissociated under feeding conditions. Treatment with human LDLs was sufficient to simulate the feeding response. Then, we observed that the overexpression of PCSK9 enhances the uptake of LDLs that are not further metabolized, while the overexpression of ANGPTL3 enhances LDL turnover. The overexpression of both proteins restored LDL uptake and degradation, which became comparable to those of control cells. In conclusion, our findings indicate the existence of an ANGPTL3-PCSK9 complex, which coordinately contributes to the regulation of intracellular lipid homeostasis, aiming to prevent cellular metabolic overload. ### Competing Interest Statement The authors have declared no competing interest.