Paola Contreras

The emergence of glucagon-like peptide-1 agonists represents a notable advancement in the pharmacological treatment of obesity, yet complementary approaches are essential. Through phenotypic drug discovery, we developed promising nitroalkene-containing small molecules for obesity-related metabolic dysfunctions. Here, we present SANA, a nitroalkene derivative of salicylate, demonstrating notable efficacy in preclinical models of diet-induced obesity. SANA reduces liver steatosis and insulin resistance by enhancing mitochondrial respiration and increasing creatine-dependent energy expenditure in adipose tissue, functioning effectively in thermoneutral conditions and independently of uncoupling protein 1 and AMPK activity. Finally, we conducted a randomized, double-blind, placebo-controlled phase 1A/B clinical trial, which consisted of two parts, each with four arms: (A) single ascending doses (200–800 mg) in healthy lean volunteers; (B) multiple ascending doses (200–400 mg per day for 15 days) in healthy volunteers with overweight or obesity. The primary endpoint assessed safety and tolerability. Secondary and exploratory endpoints included pharmacokinetics, tolerability, body weight and metabolic markers. SANA shows good safety and tolerability, and demonstrates beneficial effects on body weight and glucose management within 2 weeks of treatment. Overall, SANA appears to be a first-in-class activator of creatine-dependent energy expenditure and thermogenesis, highlighting its potential as a therapeutic candidate for ‘diabesity’. Australian New Zealand Clinical Trials Registry registration: ACTRN12622001519741.

The protein Deleted in Breast Cancer 1 (Dbc1) is an important regulator of various transcription factors and epigenetic modulators, significantly influencing metabolism, obesity, and aging-related processes. Knockout mice lacking Dbc1 exhibit severe obesity but remain protected from liver steatosis, insulin resistance, and atherosclerosis. We hypothesized that this phenotype of “healthy obesity” results from adipose tissue expansion, which prevents free fatty acid spillover and subsequent metabolic damage to peripheral tissues. To further investigate the putative role of Dbc1 in adipose cells during obesity and its effects on metabolic dysregulation, we generated conditional Dbc1 knockout (KO) mice by backcrossing with AdipoQ-CRE transgenic mice to selectively abrogate Dbc1 expression in all mature adipocytes (Dbc1^LoxP/LoxP;CRE). These mice demonstrated effective deletion of Dbc1 in mature adipocytes across various fat depots. We assessed the impact of Dbc1 deletion on metabolic regulation in male and female mice fed standard chow and high-fat diets. Our findings revealed that Dbc1 knockout in mature adipocytes did not influence weight gain, glucose tolerance, or other metabolic dysregulation markers, irrespective of sex. However, Dbc1 KO adipocytes exhibited an mRNA expression profile indicative of heightened inflammation during obesity. These results suggest that the protective phenotype observed in whole-body Dbc1 KO obese mice is not attributable to Dbc1’s function within mature adipocytes but likely involves other cell types in adipose tissue. Moreover, the specific deletion of Dbc1 in mature adipocytes unveils a novel role of Dbc1 in inflammation signaling during obesity.

Obesity-related type II diabetes (diabesity) has increased global morbidity and mortality dramatically. Previously, the ancient drug salicylate demonstrated promise for the treatment of type II diabetes, but its clinical use was precluded due to high dose requirements. In this study, we present a nitroalkene derivative of salicylate, 5-(2-nitroethenyl)salicylic acid (SANA), a molecule with unprecedented beneficial effects in diet-induced obesity (DIO). SANA reduces DIO, liver steatosis and insulin resistance at doses up to 40 times lower than salicylate. Mechanistically, SANA stimulated mitochondrial respiration and increased creatine-dependent energy expenditure in adipose tissue. Indeed, depletion of creatine resulted in the loss of SANA action. Moreover, we found that SANA binds to creatine kinases CKMT1/2, and downregulation CKMT1 interferes with the effect of SANA in vivo. Together, these data demonstrate that SANA is a first-in-class activator of creatine-dependent energy expenditure and thermogenesis in adipose tissue and emerges as a candidate for the treatment of diabesity.

Key points: Mice with Ca²⁺–calmodulin‐dependent protein kinase (CaMKII) constitutive pseudo‐phosphorylation of the ryanodine receptor RyR2 at Ser2814 (S2814D^+/+mice) exhibit a higher open probability of RyR2, higher sarcoplasmic reticulum (SR) Ca²⁺leak in diastole and increased propensity to arrhythmias under stress conditions. We generated phospholamban (PLN)‐deficient S2814D^+/+knock‐in mice by crossing two colonies, S2814D^+/+and PLNKO mice, to test the hypothesis that PLN ablation can prevent the propensity to arrhythmias of S2814D^+/+mice. PLN ablation partially rescues the altered intracellular Ca²⁺dynamics of S2814D^+/+hearts and myocytes, but enhances SR Ca²⁺sparks and leak on confocal microscopy. PLN ablation diminishes ventricular arrhythmias promoted by CaMKII phosphorylation of S2814 on RyR2. PLN ablation aborts the arrhythmogenic SR Ca²⁺waves of S2814D^+/+and transforms them into non‐propagating events. A mathematical human myocyte model replicates these results and predicts the increase in SR Ca²⁺uptake required to prevent the arrhythmias induced by a CaMKII‐dependent leaky RyR2. Mice with constitutive pseudo‐phosphorylation at Ser2814‐RyR2 (S2814D^+/+) have increased propensity to arrhythmias under β‐adrenergic stress conditions. Although abnormal Ca²⁺release from the sarcoplasmic reticulum (SR) has been linked to arrhythmogenesis, the role played by SR Ca²⁺uptake remains controversial. We tested the hypothesis that an increase in SR Ca²⁺uptake is able to rescue the increased arrhythmia propensity of S2814D^+/+mice. We generated phospholamban (PLN)‐deficient/S2814D^+/+knock‐in mice by crossing two colonies, S2814D^+/+and PLNKO mice (SD^+/+/KO). SD^+/+/KO myocytes exhibited both increased SR Ca²⁺uptake seen in PLN knock‐out (PLNKO) myocytes and diminished SR Ca²⁺load (relative to PLNKO), a characteristic of S2814D^+/+myocytes. Ventricular arrhythmias evoked by catecholaminergic challenge (caffeine/adrenaline) in S2814D^+/+micein vivoor programmed electric stimulation and high extracellular Ca²⁺in S2814D⁺/⁻heartsex vivowere significantly diminished by PLN ablation. At the myocyte level, PLN ablation converted the arrhythmogenic Ca²⁺waves evoked by high extracellular Ca²⁺provocation in S2814D^+/+mice into non‐propagated Ca²⁺mini‐waves on confocal microscopy. Myocyte Ca²⁺waves, typical of S2814D^+/+mice, could be evoked in SD^+/+/KO cells by partially inhibiting SERCA2a. A mathematical human myocyte model replicated these results and allowed for predicting the increase in SR Ca²⁺uptake required to prevent the arrhythmias induced by a Ca²⁺–calmodulin‐dependent protein kinase (CaMKII)‐dependent leaky RyR2. Our results demonstrate that increasing SR Ca²⁺uptake by PLN ablation can prevent the arrhythmic events triggered by SR Ca²⁺leak due to CaMKII‐dependent phosphorylation of the RyR2‐S2814 site and underscore the benefits of increasing SERCA2a activity on SR Ca²⁺‐triggered arrhythmias.

Heart rate variability related to heart rate decelerations and accelerations is reduced in patients with type 1 diabetes compared to healthy individuals both in resting 10-min and ambulatory 24-h ECGs.

The conventional Poincaré plot for heart rate variability (HRV) analysis is a scatterplot of successive (lag 1) pairs of RR intervals (intervals between heartbeats), and its width (SD1) is considered a measure of short-term variability. It has been shown that SD1 correlates better with HF than with LF (high- and low-frequency bands of the spectrum, respectively). Our aim was to assess how these correlations were affected when SD1 was obtained for longer lags. 10 min ECGs were used to construct Poincaré plots with lags of 1-10 heartbeats in two groups of subjects, one with normal HRV and the other with impaired HRV (control and diabetic groups respectively, N = 15 each). SD1 was quantified for these subjects and HRV spectral indices were estimated. The diabetic group had lower LF, HF and SD1 than the control group (p < 0.05). In both groups, SD1 tended to increase as the lag increased. In the control group, SD1 for lags 1 and 2 was highly correlated with HF (r(s) > 0.9), while SD1 for lags 4 correlated better with LF (r(s) 0.9) than with HF (0.65 <or= r(s) <or= 0.73). However, in the diabetic group, the correlation results did not change in that way for different lags (correlation results between HF and SD1: r(s) 0.95 for lags 1-10). In conclusion, the comparative strength of the correlations between lagged Poincaré widths and spectral indices might be useful to distinguish normal from pathological HRV.