Zheng, Ye

Background: The cardiac hormone atrial natriuretic peptide is the endogenous ligand for the guanylyl cyclase A (GC-A) receptor. The ANP/GC-A/cGMP pathway is a key regulator of cardiorenal and metabolic homeostasis. Beyond its classical natriuretic and vasodilatory roles, emerging evidence reveals that ANP via GC-A stimulates lipolysis in human adipocytes and modulates insulin secretion. Notably, the ANP gene variant rs5068, which enhances ANP production, is associated with reduced risk of obesity and metabolic syndrome in humans. We recently engineered CRRL191, a novel best-in-class GC-A agonist, with superior receptor activation and greater resistance to degradation by neprilysin and insulin degrading enzyme resulting in greater blood pressure lowering and natriuretic effects than ANP. Given the metabolic properties of GC-A signaling, we investigated CRRL191’s metabolic effects on lipolysis and insulin secretion in pancreatic, including its interaction with GLP-1. Hypothesis: CRRL191 exerts potent lipolytic and insulinotropic effects and synergizes with GLP-1 to enhance insulin secretion. Methods: Human visceral adipocytes were treated with CRRL191 (10 -8 -10 -6 M) for 6 hrs. Lipolysis was assessed by measuring glycerol and non-esterified fatty acids (NEFA) in supernatants. Rat pancreatic beta cells (INS-1) were stimulated treated with CRRL191 (10 -10 -10 -6 M), GLP-1 (10 -10 -10 -6 M) alone or their combination for 1 hr. Insulin secretion was quantified by ELISA. Results: CRRL191 stimulated lipolysis in human visceral adipocytes (10 -8 -10 -6 M), increasing glycerol and NEFA release. CRRL191 induced greater glycerol release than GLP-1 across all tested doses, with low dose CRRL191 (10 -10 M) notably enhancing NEFA production. In INS-1 cells, CRRL191 dose dependently increased insulin secretion under hyperglycemic conditions, demonstrating superior potency at lower concentrations (10 -10 and 10 -8 M) compared to GLP-1. Remarkably, co-administration of CRRL191 with GLP-1 amplified insulin release beyond levels achieved by either peptide alone. Conclusion: CRRL191 is a potent GC-A agonist that robustly stimulates lipolysis in visceral adipocytes and enhances insulin secretion in pancreatic beta cells. Its synergistic interaction with GLP-1 highlights a novel therapeutic avenue targeting the GC-A/cGMP pathway for integrated treatment of cardiometabolic diseases. These findings support further evaluation of CRRL191 as a promising candidate for cardiometabolic drug development.

Background: Heart failure (HF) is a complex syndrome marked by adverse cardiac remodeling and natriuretic peptide (NP) deficiency, which drives disease progression despite current therapies. NPs exert cardioprotective effects via particulate guanylate cyclase receptors GC-A and GC-B, which generate cGMP. Activation of GC-A by ANP or BNP induces arteriodilation, natriuresis, antihypertrophic effects, and inhibits the renin-angiotensin-aldosterone system, while GC-B activation by CNP mediates antifibrotic, lusitropic, venodilatory, and anti-inflammatory actions. Existing drugs target either GC-A or GC-B, but none target both. We developed RT-A1, a unimolecular peptide activating both GC-A and GC-B, hypothesizing it will attenuate myocardial remodeling in a preclinical model of HF with preserved systolic function. Methods: RT-A1 was engineered by rational drug design. HEK293 cells expressing human GC-A or GC-B, human cardiac myocytes (CMs) and fibroblasts (CFs) were treated with RT-A1 (10-100nM) and cGMP was measured. In vivo, mice underwent mild transverse aortic constriction (TAC) or sham surgery. After 3 weeks, LV hypertrophy (LVH) was confirmed by echo. TAC mice were then randomized to vehicle (Veh) or RT-A1 (50pmol/kg/min) via subcutaneous osmotic pumps for 3 weeks. Endpoints included LV/body weight ratio, myocyte cross-sectional area (CSA), plasma cGMP, and RNA-seq. Data are mean±SEM. P<0.05 was significant. Results: RT-A1 dose-dependently increased cGMP in HEK293 cells expressing GC-A or GC-B, confirming dual activation, and elevated cGMP in human CMs and CFs. TAC induced significant LV wall thickening with preserved systolic function versus sham. After three weeks, RT-A1 normalized LV/body weight (3.14±0.14 vs. 3.82±0.29, P=0.03) and reduced myocyte CSA (348±16 vs. 506±17, P=0.0005) compared to Veh. Plasma cGMP was higher in TAC+RT-A1 versus TAC+Veh (85±8 vs 54±8 pmol/ml, P=0.01), confirming target engagement. RNA-seq showed reduced LV BNP expression and downregulation of hypertrophy, fibrosis, and inflammation pathways with RT-A1 treatment vs. Veh following TAC. Conclusions: RT-A1 is a novel dual GC-A/GC-B peptide activator that elevates plasma cGMP and reduces adverse cardiac remodeling in experimental HF by downregulating hypertrophy, fibrosis, and inflammation pathways. Dual GC-A/GC-B activation via RT-A1 represents a promising anti-remodeling therapeutic strategy for HF with preserved systolic function warranting further study.

Background: Diabetic cardiomyopathy is a common complication of diabetes, which can progress to symptomatic heart failure. Current conventional medical therapy does not reverse the deleterious features of diabetic cardiomyopathy. The natriuretic peptide-cGMP system has been proven to provide a cardioprotective role in diabetic rats. Therefore, we developed CRRL094, a n bispecific peptide that simultaneously activates the natriuretic peptide system and glucagon-like peptide-1 (GLP-1) receptor. In this study, we aimed to characterize the cardioprotective role of CRRL094 and elucidate its downstream molecular mechanisms. Methods: In vitro, human cardiomyocytes (HCMs) were pretreated with PBS or CRRL094 (5 µM) for 6 hours, then exposed to high glucose treatment (HGT, 25 mM) for 48 hours. HCM hypertrophy was determined by assessing mRNA levels of hypertrophic gene markers (NPPA and NPPB) using real-time PCR. Lipid droplet staining was performed using BODIPY 493/503 dye and fluorescence images were analyzed. The protein levels of CIDEC (lipid droplet-related gene) and phosphorylation-AMPK and total AMPK (a key regulator of lipid metabolism) were analyzed by Western blot. In vivo, a type 2 diabetes (DM2) rat model was established by low-dose intraperitoneal Streptozotocin (STZ) injection and a high-fat diet in Wistar rats (male, 4- to 6-week-old). Diabetes was confirmed by fasting blood glucose > 350 mg/dL. Rats were then allocated to two groups: saline-treated controls (n=6) or CRRL094-treated (30 pmol/kg/min; n=6), with treatment delivered via osmotic pumps for 28 days. Heart tissues were collected and analyzed. Results: HGT in HCMs significantly increased the mRNA levels of NPPA and NPPB, whereas CRRL094 significantly attenuated markers of hypertrophy. Further, HGT increased lipid accumulation in HCMs, which was decreased with CRRL094 treatment. Moreover, CRRL094 increased p-AMPK protein levels and decreased CIDEC protein levels in HCMs under HGT. In a DM2 rat model, chronic CRRL094 therapy was associated with suppression of NPPA and NPPB, downregulation of CIDEC, and upregulation of p-AMPK expression in the heart tissue. Conclusion: CRRL094 protects against HGT-induced hypertrophy and inhibits lipid accumulation through regulating the AMPK/CIDEC pathway in vitro and in vivo . These findings support CRRL094 as a novel therapeutic candidate to prevent diabetic cardiomyopathy.

Introduction: Diabetes mellitus (DM) is strongly associated with metabolic and cardiorenal derangements. Natriuretic peptides (NPs), and glucagon-like peptide 1 receptor agonists (GLP-1 RA) have well-established cardiometabolic and cardiorenal protective effects. We developed a novel bispecific biologic, CRRL 101, which agonizes guanylyl cyclase A (GCA) NP receptors and GLP-1 receptors. In this study, we sought to evaluate the in vitro effects and in vivo impact of CRRL 101 in a DM rat model. Methods: In vitro experiments evaluated the impact of CRRL 101 treatment of GCA receptor transfected human embryonic kidney (HEK) cells and INS-1 rat pancreatic beta cells. In vivo experiments were conducted by inducing DM in Wistar rats (male, 6-8-week-old) by intraperitoneal Streptozotocin (STZ) injection (65 mg/kg). One week after STZ injection, DM was confirmed (fasting blood glucose > 350 mg/dL). Rats were then divided into 3 groups: saline control (n=6), 1 pmol/kg/min CRRL-101 (“1pmol” n= 4), and 10 pmol/kg/min CRRL-101 (“10 pmol” n=5). Treatment was infused for 120 min after which rat blood and urine were collected. Data were analyzed using GraphPad Prism 10.0.0. Results: In vitro, there was a marked increase in cyclic GMP (cGMP) levels (pmol/mL) in HEK treated with 10 -6 M CRRL 101 (mean difference ± SEM:1.603 ± 0.29 p = 0.0048). In INS-1 cells treated with CRRL 101 at 10 -6 M in a 20 mM glucose medium, cAMP levels (pmol/mL) markedly increased (16.7 ± 1.47 vs 23.19 ± 1.51 p=0.0036) and insulin levels (ng/mL) doubled (4.4 ng/mL ± 0.44 vs 9.5 ng/mL ± 0.34 in 20 mM glucose p < 0.0001). Similar increases were observed at lower doses (10 -7 M, 10 -8 M) of CRRL 101. In vivo , after 120 minutes of treatment, mean plasma cGMP levels were 6.5x greater in both groups (mean difference± SEM) (1pmol: 38.89 ± 7.93, p = 0.016; 10pmol: 39.40 ± 4.84 p=0.001). Plasma insulin (ng/mL) more than doubled with both doses (1pmol: 0.39 ± 0.148, p = 0.039; 10 pmol: 0.198 ± 0.051, p = 0.004) with no significant increase with placebo ( 0.03 ± 0.08, p = 0.67). Rate of natriuresis (mEq/min) more than doubled with peptide administration vs placebo (1 pmol: 0.36 ± 0.093 p = 0.014; 10 pmol: 0.38 ± 0.13, p = 0.034). Conclusions: Our novel bispecific biologic, CRRL 101, activates GC-A, increasing plasma cGMP and inducing natriuresis, and stimulates GLP-1R, raising cAMP and plasma insulin. Chronic administration studies to eludicate its therapeutic efficacy are warranted.

BACKGROUND: Cardiomyocyte oxidative stress significantly contributes to the progression of hypertension-induced heart failure, highlighting the need for targeted therapies. We developed a novel peptide, NPA7, that coactivates the GC-A (guanylyl cyclase A)/cGMP and MasR (Mas receptor)/cAMP pathway. This study aimed to test NPA7’s ability to inhibit oxidative stress by modulating the p62 (Sequestosome 1)-KEAP1 (Kelch-like ECH-associated protein 1)-NRF2 (nuclear factor erythroid 2-related factor 2) pathway in human cardiomyocytes (HCMs) and a rat model of hypertension. METHODS: Oxidative stress was induced in HCMs using H 2 O 2 with phosphate-buffered saline or NPA7 treatment. Intracellular reactive oxygen species levels were assessed via dihydroethidium staining. Western blotting analysis measured p62, KEAP1, and NRF2 protein levels, while GSH/GSSG (glutathione/glutathione disulfide) ratios and antioxidant gene expression were analyzed. HCMs were transfected with small interfering RNA targeting GC-A, MasR, or p62 before NPA7 and H 2 O 2 treatment. In vivo, spontaneously hypertensive rats received saline or NPA7, with normotensive Wistar Kyoto rats as control and cardiac oxidative stress, KEAP1 protein levels, NOX2 (NADPH oxidase 2), and p67 (NADPH oxidase subunit p67-phox) mRNA levels were measured. RESULTS: NPA7 reduced H 2 O 2 -induced reactive oxygen species levels and increased GSH/GSSG ratio in HCMs. Silencing GC-A (guanylyl cyclase A receptor) and MasR (Mas receptor) reversed NPA7’s effects. NPA7 activated the KEAP1-NRF2 pathway, enhancing NRF2’s antioxidant target gene expression. In p62 knockdown HCMs, NPA7-induced KEAP1 degradation and NRF2 activation were diminished. Reactive oxygen species levels were elevated in spontaneously hypertensive rat versusWistar Kyoto rats’ hearts, however, NPA7 treatment reduced myocardial reactive oxygen species, suppressed KEAP1 protein, and decreased NOX2 and p67 mRNA levels. CONCLUSIONS: NPA7 exhibits antioxidant properties in HCMs and spontaneously hypertensive rat hearts by targeting GC-A and MasR through the p62-KEAP1-NRF2 pathway, supporting a novel therapeutic approach against cardiovascular disease–related oxidative stress.

BACKGROUND: Atrial natriuretic peptide (ANP) and glucagon-like peptide-1 (GLP-1) are endogenous hormones known for roles in cardiovascular regulation and metabolic homeostasis. ANP mediates its actions via the GC-A receptor, while GLP-1 via the GLP-1 receptor (GLP-1R). Both peptides may stimulate insulin secretion from pancreatic beta cells and augment lipid metabolism in adipocytes, yet potential synergistic effects remain unexplored. To optimize ANP activation of GC-A, we developed a novel 15 amino acid miniaturized GC-A activating peptide CRRL555. CRRL555 possesses greater GC-A binding and activating properties than ANP. AIMS: We investigated the metabolic properties of CRRL555/GC-A and its interaction with GLP-1/GLP-1R in vitro. METHODS: Rat pancreatic beta cells (INS-1) were stimulated with high glucose (20mM) and treated with GLP-1 or CRRL555 (10 -10 -10 -6 M) and together for 1 hr. Supernatant was collected and insulin was measured by ELISA. Human visceral adipocytes were differentiated for 10 days and then treated with GLP-1 or CRRL555 (10 -10 -10 -6 M) or together for 6 hrs. Supernatant was collected and glycerol and free fatty acid (NEFA), indicators of lipolysis, were measured. RESULTS: CRRL555 (p<0.05) and GLP-1 (p<0.05), dose dependently, stimulated insulin secretion in INS-1 cells in the presence of high glucose. Importantly, CRRL555 combined with GLP-1, resulted in a greater enhancement (p<0.05) of insulin secretion compared to either peptide alone. While high dose CRRL555 and GLP-1 (10 -6 M) stimulated lipolysis in visceral adipocytes with increases in glycerol and NEFA, only CRRL555 at low dose (10 -10 M), and not low dose GLP-1 (10 -10 M), stimulated glycerol and NEFA production (p<0.05). When low dose GLP-1 (10 -10 M) was added to low dose CRRL555(10 -10 M), lipolysis was like CRRL555 alone. CONCLUSION: We report a novel synergy in insulin release from beta cells with combined stimulation of the potent and miniaturized GC-A designer peptide CRRL555 with GLP-1. CRRL555 possesses greater lipolytic properties compared to GLP-1 in visceral adipocytes at low doses advancing novel metabolic actions of CRRL555 alone or combined with GLP-1R activation. These in vitro studies of dual receptor activation of GC-A and GLP-1R highlight the therapeutic potential of combining CRRL555 with GLP-1-based therapies for the treatment of cardiometabolic diseases, thus supporting studies of dual GC-A/GLP-1R activation in experimental cardiometabolic disease states.

Abstract Myocardial fibrosis is a pathological hallmark of cardiovascular disease (CVD), and excessive fibrosis can lead to new-onset heart failure and increased mortality. Currently, pharmacological therapies for myocardial fibrosis are limited, highlighting the need for novel therapeutic approaches. The particulate guanylyl cyclase B (GC-B) receptor possesses beneficial antifibrotic actions through the binding of its natural ligand C-type natriuretic peptide (CNP) and the generation of the intracellular second messenger, cyclic guanosine 3′,5′-monophosphate (cGMP). These actions include the suppression of fibroblast proliferation and reduction in collagen synthesis. With its abundant expression on fibroblasts, the GC-B receptor has emerged as a key molecular target for innovative CVD therapeutics. However, small molecules that can bind and potentiate the GC-B/cGMP pathway have yet to be discovered. From a cell-based high-throughput screening initiative of the NIH Molecular Libraries Small Molecule Repository and hit-to-lead evolution based on a series of structure–activity relationships, we report the successful discovery of MCUF-42, a GC-B-targeted small molecule that acts as a positive allosteric modulator (PAM). Studies herein support MCUF-42's ability to enhance the binding affinity between GC-B and CNP. Moreover, MCUF-42 potentiated cGMP levels induced by CNP in human cardiac fibroblasts (HCFs) and notably also enhanced the inhibitory effect of CNP on HCF proliferation. Together, our findings highlight that MCUF-42 is a small molecule that can modulate the GC-B/cGMP signaling pathway, potentially enhancing the antifibrotic actions of CNP. Thus, these data underscore the continued development of GC-B small molecule PAMs as a novel therapeutic strategy for targeting cardiac fibrosis and CVD.

The natriuretic peptide system (NPS) and renin-angiotensin-aldosterone system (RAAS) function oppositely at multiple levels. While it has long been suspected that angiotensin II (ANGII) may directly suppress NPS activity, no clear evidence to date supports this notion. This study was designed to systematically investigate ANGII–NPS interaction in humans, in vivo, and in vitro. Circulating atrial, b-type, and c-type natriuretic peptides (ANP, BNP, CNP), cyclic guanosine monophosphate (cGMP), and ANGII were simultaneously investigated in 128 human subjects. Prompted hypothesis was validated in vivo to determine the influence of ANGII on ANP actions. The underlying mechanisms were further explored via in vitro approaches. In humans, ANGII demonstrated an inverse relationship with ANP, BNP, and cGMP. In regression models predicting cGMP, adding ANGII levels and the interaction term between ANGII and natriuretic peptides increased the predictive accuracy of the base models constructed with either ANP or BNP, but not CNP. Importantly, stratified correlation analysis further revealed a positive association between cGMP and ANP or BNP only in subjects with low, but not high, ANGII levels. In rats, co-infusion of ANGII even at a physiological dose attenuated cGMP generation mediated by ANP infusion. In vitro, we found the suppressive effect of ANGII on ANP-stimulated cGMP requires the presence of ANGII type-1 (AT1) receptor and mechanistically involves protein kinase C (PKC), as this suppression can be substantially rescued by either valsartan (AT1 blocker) or Go6983 (PKC inhibitor). Using surface plasmon resonance (SPR), we showed ANGII has low binding affinity to the guanylyl cyclase A (GC-A) receptor compared to ANP or BNP. Our study reveals ANGII is a natural suppressor for the cGMP-generating action of GC-A via AT1/PKC dependent manner and highlights the importance of dual-targeting RAAS and NPS in maximizing beneficial properties of natriuretic peptides in cardiovascular protection.

Significance The particulate guanylyl cyclase A receptor (GC-A), via its endogenous cardiac-derived hormones atrial natriuretic peptide (ANP) and b-type natriuretic peptide (BNP), plays a pivotal role in maintaining intravascular volume, arterial pressure, cardiovascular structure, function, and, more recently, metabolic homeostasis. As such, therapies to potentiate GC-A signaling via peptide augmentation have yielded promising results in clinical trials. A major breakthrough in GC-A therapeutics would be a small molecule that sensitizes the GC-A receptor to endogenous ANP or BNP, which to date does not exist. Here, we report the development of an orally bioavailable, small molecule positive allosteric modulator of GC-A that exhibits therapeutic activity in human hypertension and heart failure ex vivo.

Rationale: Acute kidney injury (AKI) has a high prevalence and mortality in critically ill patients. It is also a powerful risk factor for heart failure incidence driven by hemodynamic changes and neurohormonal activation. However, no drugs have been approved by the Food and Drug Administration. Endogenous pGC-A (particulate guanylyl cyclase A receptor) activators were reported to preserve renal function and improve mortality in AKI patients, although hypotension accompanied by pGC-A activators have limited their therapeutic potential. Objective: We investigated the therapeutic potential of a nonhypotensive pGC-A activator/designer natriuretic peptide, CRRL269, in a short-term, large animal model of ischemia-induced AKI and also investigated the potential of uCNP (urinary C-type natriuretic peptide) as a biomarker for AKI. Methods and Results: We first showed that CRRL269 stimulated cGMP generation, suppressed plasma angiotensin II, and reduced cardiac filling pressures without lowering blood pressure in the AKI canine model. We also demonstrated that CRRL269 preserved glomerular filtration rate, increased renal blood flow, and promoted diuresis and natriuresis. Further, CRRL269 reduced kidney injury and apoptosis as evidenced by ex vivo histology and tissue apoptosis analysis. We also showed, compared with native pGC-A activators, that CRRL269 is a more potent inhibitor of apoptosis in renal cells and induced less decreases in intracellular Ca 2+ concentration in vascular smooth muscle cells. The renal antiapoptotic effects were at least mediated by cGMP/PKG pathway. Further, CRRL269 inhibited proapoptotic genes expression using a polymerase chain reaction gene array. Additionally, we demonstrated that AKI increased uCNP levels. Conclusions: Our study supports developing CRRL269 as a novel renocardiac protective agent for AKI treatment.