Karol Mateusz Pencina

Aims: Apolipoprotein B (apoB) is the most accurate causal lipid factor associated with increased risk of atherosclerotic cardiovascular disease (ASCVD). While high HDL cholesterol has been considered protective, HDL-C–raising therapies have not shown benefit. Objective: To assess whether HDL-C provides independent information from apoB and whether HDL-C modifies the effect of apoB on ASCVD risk. Methods and results: 293 872 UK Biobank participants aged 37–73, free of CVD, not on lipid-lowering medication, and with complete standard risk factor data were followed for 10 years for incident ASCVD. Cox proportional hazard models, adjusted for standard risk factors, including log-triglycerides, used apoB and HDL-C residuals (regressed on each other) as primary exposures. Interaction between apoB and HDL-C was tested separately. When HDL-C residual was added to a model with apoB, both were significant: hazard ratios (HRs) per 1 SD were 1.16 (95% confidence interval, CI: 1.15–1.18; P < 0.001) for apoB and 0.85 (95% CI: 0.84–0.87; P < 0.001) for HDL-C residual. Similarly, adding apoB residual to a model with HDL-C yielded HRs of 1.14 (95% CI: 1.12–1.16; P < 0.001) for apoB residual and 0.84 (95% CI: 0.82–0.85; P < 0.001) for HDL-C. The apoB–HDL-C interaction was significant: HR 0.95 (95% CI: 0.93–0.96; P < 0.001), consistent across sexes. Conclusion: High HDL-C is associated with lower ASCVD risk, independent of apoB, and it attenuates the effect of high apoB on ASCVD risk. These findings suggest HDL-C’s role in primary ASCVD prevention warrants re-evaluation. However, findings from an observational study, such as this, do not establish causation.

Background: Testosterone, estradiol, and dihydrotestosterone share common ligand binding sites on sex hormone binding globulin and albumin. It is unknown whether and how changes in testosterone, dihydrotestosterone, and estradiol concentrations during testosterone replacement therapy affect free testosterone fraction.Objective: To determine the effect of changes in testosterone, dihydrotestosterone, and estradiol concentrations on free testosterone fraction during testosterone replacement therapy of men with hypogonadism.Methods: Using data from the Testosterone Trials, we assessed the association of changes in total testosterone, estradiol, and dihydrotestosterone concentrations over 12 months of testosterone replacement therapy with changes in free testosterone fraction, measured using equilibrium dialysis. We used random forests to evaluate the associations of predicted mean changes in free testosterone fraction with changes in circulating concentrations of each hormone at low, mean, or high change in the other two hormones.Results: Testosterone replacement therapy not only increased total testosterone, dihydrotestosterone, estradiol, and free testosterone concentrations, but also the percent free testosterone, even though sex hormone binding globulin levels did not change. The predicted changes in free testosterone fraction during testosterone replacement therapy exhibited a non‐linear relationship with changes in each of total testosterone, dihydrotestosterone, and estradiol concentrations. Greater increases in testosterone, dihydrotestosterone, and estradiol levels during testosterone replacement therapy were each associated with higher model‐predicted percent free testosterone. Substantially smaller changes in molar concentrations of estradiol and dihydrotestosterone had a greater effect on percent free testosterone than those in testosterone.Conclusion: During testosterone replacement therapy of men with hypogonadism, changes in testosterone, dihydrotestosterone, and estradiol concentrations each altered percent free testosterone non‐linearly. Small changes in estradiol concentrations exerted much larger effect on the free testosterone fraction than testosterone and dihydrotestosterone, suggesting complex interactions of the three hormones with the binding proteins. Assessment of changes in free testosterone during testosterone replacement therapy should include consideration of changes in all three hormones.

Despite growing evidence that apolipoprotein B (apoB) is the most accurate marker of atherosclerotic cardiovascular disease (ASCVD) risk, its adoption in clinical practice has been low. This investigation sought to determine whether low-density lipoprotein cholesterol (LDL-C), non–high-density lipoprotein cholesterol (HDL-C), and triglycerides are sufficient for routine cardiovascular care. A sample of 293 876 UK Biobank adults (age: 40–73 years, 42% men), free of cardiovascular disease, with a median follow-up for new-onset ASCVD of 11 years was included. Distribution of apoB at pre-specified levels of LDL-C, non-HDL-C, and triglycerides was examined graphically, and 10-year ASCVD event rates were compared for high vs. low apoB. Residuals of apoB were constructed after regressing apoB on LDL-C, non-HDL-C, and log-transformed triglycerides and used as predictors in a proportional hazards regression model for new-onset ASCVD adjusted for standard risk factors, including HDL-C. ApoB was highly correlated with LDL-C and non-HDL-C (Pearson’s r = .96, P < .001 for both) but less so with log triglycerides (r = .42, P < .001). However, apoB ranges necessary to capture 95% of all observations at pre-specified levels of LDL-C, non-HDL-C, or triglycerides were wide, spanning 85.8–108.8 md/dL when LDL-C 130 mg/dL, 88.3–112.4 mg/dL when non-HDL-C 160 mg/dL, and 67.8–147.4 md/dL when triglycerides 115 mg/dL. At these levels (±10 mg/dL), 10-year ASCVD rates for apoB above mean + 1 SD vs. below mean − 1 SD were 7.3 vs. 4.0 for LDL-C, 6.4 vs. 4.6 for non-HDL-C, and 7.0 vs. 4.6 for triglycerides (all P < .001). With 19 982 new-onset ASCVD events on follow-up, in the adjusted model, residual apoB remained statistically significant after accounting for LDL-C and HDL-C (hazard ratio 1.06, 95% confidence interval 1.0–1.07), after accounting for non-HDL-C and HDL-C (hazard ratio 1.04, 95% confidence interval 1.03–1.06), and after accounting for triglycerides and HDL-C (hazard ratio 1.13, 95% confidence interval 1.12–1.15). None of the residuals of LDL-C, non-HDL-C, or of log triglycerides remained significant when apoB was included in the model. High variability of apoB at individual levels of LDL-C, non-HDL-C, and triglycerides coupled with meaningful differences in 10-year ASCVD rates and significant residual information contained in apoB for prediction of new-onset ASCVD events demonstrate that LDL-C, non-HDL-C, and triglycerides are not adequate proxies for apoB in clinical care. Illustration of residual discordance and variance analysis of apoB and LDL-C/non-HDL-C in UK Biobank. LDL-C, low-density lipoprotein cholesterol; non-HDL-C, non–high-density lipoprotein cholesterol; apoB, apolipoprotein B.

Context Nicotinamide adenine dinucleotide (NAD) levels decline with aging and age-related decline in NAD has been postulated to contribute to age-related diseases. Objective We evaluated the safety and physiologic effects of NAD augmentation by administering its precursor, β-nicotinamide mononucleotide (MIB-626, Metro International Biotech, Worcester, MA), in adults at risk for age-related conditions. Methods Thirty overweight or obese adults, ≥ 45 years, were randomized in a 2:1 ratio to 2 MIB-626 tablets each containing 500 mg of microcrystalline β-nicotinamide mononucleotide or placebo twice daily for 28 days. Study outcomes included safety; NAD and its metabolome; body weight; liver, muscle, and intra-abdominal fat; insulin sensitivity; blood pressure; lipids; physical performance, and muscle bioenergetics. Results Adverse events were similar between groups. MIB-626 treatment substantially increased circulating concentrations of NAD and its metabolites. Body weight (difference −1.9 [−3.3, −0.5] kg, P = .008); diastolic blood pressure (difference −7.01 [−13.44, −0.59] mmHg, P = .034); total cholesterol (difference −26.89 [−44.34, −9.44] mg/dL, P = .004), low-density lipoprotein (LDL) cholesterol (−18.73 [−31.85, −5.60] mg/dL, P = .007), and nonhigh-density lipoprotein cholesterol decreased significantly more in the MIB-626 group than placebo. Changes in muscle strength, muscle fatigability, aerobic capacity, and stair-climbing power did not differ significantly between groups. Insulin sensitivity and hepatic and intra-abdominal fat did not change in either group. Conclusions MIB-626 administration in overweight or obese, middle-aged and older adults safely increased circulating NAD levels, and significantly reduced total LDL and non-HDL cholesterol, body weight, and diastolic blood pressure. These data provide the rationale for larger trials to assess the efficacy of NAD augmentation in improving cardiometabolic outcomes in older adults.

Background: Free testosterone (FT) determination may be helpful in evaluating men suspected of testosterone deficiency especially in conditions with altered binding‐protein concentrations. However, methods for measuring FT by equilibrium dialysis and reference intervals vary among laboratories.Objective: To determine reference intervals for FT in healthy, nonobese men by age groups as well as in healthy young men, 19–39 years, using a standardized equilibrium dialysis procedureMethods: We measured FT in 145 healthy, nonobese men, 19 years or older, using a standardized equilibrium dialysis method performed for 16‐h at 37°C using undiluted serum and dialysis buffer that mimicked the ionic composition of human plasma. FT in dialysate was measured using a CDC‐certified liquid chromatography tandem mass spectrometry assay.Results: In healthy nonobese men, the 2.5th, 10th, 50th, 90th, and 97.5th percentile values for FT were 66, 91, 141, 240, and 309 pg/ml, respectively; corresponding values for men, 19–39 years, were 120, 128, 190, 274, and 368 pg/ml, respectively. FT levels by age groups exhibit the expected age‐related decline. FT levels were negatively associated with body mass index, age, and sex hormone‐binding globulin (SHBG) levels. Percent FT was lower in middle‐aged and older men than young men adjusting for SHBG level.Discussion: Further studies are needed to determine how these reference intervals apply to the diagnosis of androgen deficiency in clinical populations and in men of different races and ethnicities in different geographic regions.Conclusion: Reference intervals for free FT levels (normative range 66–309 pg/ml [229–1072 pmol/L] in all men and 120–368 pg/ml [415–1274 pmol/L] in men, 19–39 years), measured using a standardized equilibrium dialysis method in healthy nonobese men, provide a rational basis for categorizing FT levels. These intervals require further validation in other populations, in relation to outcomes, and in randomized trials.

Context Selective androgen receptor modulators (SARMs), because of their preferential muscle vs prostate selectivity, are being developed for muscle-wasting conditions. Oral SARMs suppress high-density lipoprotein cholesterol (HDL-C) but their effects on functional capacity and atherogenic potential of HDL particles are unknown. Objective To determine the effects of an oral SARM (OPK-88004) on cholesterol efflux capacity, HDL particle number and size, apolipoprotein particle number and size and HDL subspecies Methods We measured cholesterol efflux capacity (CEC); HDL particle number and size; APOB; APOA1; and protein-defined HDL subspecies associated with coronary heart disease (CHD) risk in men, who had undergone prostatectomy for low-grade prostate cancer during 12-week treatment with placebo or 1, 5, or 15 mg of an oral SARM (OPK-88004). Results SARM significantly suppressed HDL-C (P < .001) but HDL particle size did not change significantly. SARM had minimal effect on CEC of HDL particles (change + 0.016, –0.036, +0.070, and –0.048%/µmol-HDL/L^–1 at 0, 1, 5, and 15 mg SARM, P = .045). SARM treatment suppressed APOAI (P < .001) but not APOB (P = .077), and reduced APOA1 in HDL subspecies associated with increased (subspecies containing α2-macroglobulin, complement C3, or plasminogen) as well as decreased (subspecies containing APOC1 or APOE) CHD risk; relative proportions of APOA1 in these HDL subspecies did not change. SARM increased hepatic triacylglycerol lipase (HTGL) (P < .001). Conclusion SARM treatment suppressed HDL-C but had minimal effect on its size or cholesterol efflux function. SARM reduced APOA1 in HDL subspecies associated with increased as well as decreased CHD risk. SARM-induced increase in HTGL could contribute to HDL-C suppression. These data do not support the simplistic notion that SARM-associated suppression of HDL-C is necessarily proatherogenic; randomized trials are needed to determine SARM’s effects on cardiovascular events.

Background: People living with HIV (PLWH) are disproportionately burdened with multimorbidity and decline in physiologic function compared with their uninfected counterparts, but biological mechanisms that differentially contribute to the decline in muscle function in PLWH compared with uninfected people remain understudied. Setting: The study site was Brigham and Women's Hospital, Harvard Medical School, Boston, MA. Methods: We evaluated skeletal muscle tissue for levels of total nicotinamide adenine dinucleotide (NAD), NAD⁺, and nicotinamide adenine dinucleotide (NADH) in middle-aged asymptomatic PLWH, coinfected with hepatitis C virus and/or cytomegalovirus and compared them with uninfected control participants. Results: Of the 54 persons with muscle biopsy data, the mean age was 57 years with 33% women. Total NAD levels declined in skeletal muscle in association with HIV infection and was exacerbated by hepatitis C virus and cytomegalovirus coinfection, with lowest levels of total NAD, NAD⁺, and NADH among persons who were coinfected with all 3 viruses (P = 0.015, P = 0.014, and P = 0.076, respectively). Levels of total NAD, NAD⁺, and NADH in skeletal muscle were inversely associated with inflammation (P = 0.014, P = 0.013, and P = 0.055, respectively). Coinfections were also associated with measures of inflammation (CD4/CD8 ratio: P < 0.001 and sCD163: P < 0.001) and immune activation (CD38 and human leukocyte antigen-DR expression on CD8 T cells: P < 0.001). In addition, coinfection was associated with increased physiologic frailty based on the Veteran Aging Cohort Study 1.0 index assessment (P = 0.001). Conclusions: Further research is warranted to determine the clinical relevance of preclinical deficits in NAD metabolites in skeletal muscle in association with viral coinfection and inflammation, as well as the observed association between viral coinfection and physiologic frailty.

Background: Testosterone treatment increases erythrocytes in men, but its effects on leukocyte and platelet counts are unknown and could affect its safety.Objective: To determine whether testosterone affects circulating leukocytes and platelets in men.Methods: Secondary analyses of two randomized testosterone trials were performed: the 5α‐reductase (5aR) and OPTIMEN trials. In 5aR trial, 102 healthy men, 21‐50 years (mean age 38), received a long‐acting GnRH agonist, and 50, 125, 300, or 600 mg/week testosterone enanthate (TE) plus placebo or 2.5 mg_/day dutasteride for 20 weeks. In OPTIMEN, 78 functionally limited men, ≥65 years (mean age 72) with protein intake ≤ 0.83 g kg⁻¹ day⁻¹, were randomized to controlled diets with 0.8 g kg⁻¹ day⁻¹ protein or 1.3 g kg⁻¹ day⁻¹ protein plus placebo or TE (100 mg/week) for 6 months. Changes from baseline in total and differential leukocyte count, and platelet count were evaluated.Results: In 5aR, testosterone administration was associated with increases in total leukocyte (estimated change from baseline 40, 490, 1230, and 1280 cells/µL, P < .001), neutrophil (65.1, 436.1, 1177.2, and 1192.2 cells/µL, P < .001), monocyte (−20.2, 24.5, 90.6, and 143.9 cells/µL, P < .001), platelet (−7.3, 8.4, 8.7, and 8.9 × 10³ cells/µL, P = .033), and erythrocyte counts. Testosterone did not affect absolute lymphocyte count. Similar increase in total leukocyte count was observed with testosterone treatment in OPTIMEN (change 0.77 × 10³ cells/µL, P vs placebo = 0.004).Conclusions: Testosterone administration in men differentially increases neutrophil and monocyte counts. These findings, together with its erythropoietic effects, suggest that testosterone promotes the differentiation of hematopoietic progenitors into the myeloid lineage. These findings have potential mechanistic, therapeutic, and safety implications.