Cinaciguat

Cinaciguat is a soluble Guanylyl Cyclase (sGC) activator that plays a crucial role in cardiovascular diseases. Previous research has shown that cinaciguat is involved in the progression of cardiomyopathy, which encompasses cardiac enlargement, heart dysfunction, and doxorubicin-induced heart damage. However, its therapeutic potential in sepsis-induced cardiomyopathy remains unknown.

This study examined the impact of cinaciguat on Lipopolysaccharide (LPS)-induced myocardial injury and the underlying molecular mechanisms.

The mice model was established through intraperitoneal injection of LPS (10 mg/kg), and an in vitro model was generated by stimulating H9C2 cells with LPS (10 μg/ml) for 12 h. Subsequently, the sGC activator cinaciguat was used to assess its effects on LPS-induced cardiac injury. Additionally, echocardiography was conducted 12 hours after modeling to analyze cardiac function in mice. We used various methods to evaluate inflammation, and apoptosis, including Enzyme-Linked Immunosorbent Assay (ELISA), terminal deoxynucleotidyl transferase-mediated deoxyuridine Triphosphate Nick End Labeling (TUNEL) assay, Hematoxylin and Eosin (H&E) staining, western blotting and Real-Time Polymerase Chain Reaction (RT-PCR). Additionally, the protein kinase cGMP-dependent 1 (PRKG1)/cAMP-Response Element Binding protein (CREB) signaling pathway and Mitochondrial Ferritin (FtMt) in LPS-induced cardiac injury was assessed via Western blot analysis.

LPS-induced cardiac dysfunction and increased levels of cardiac injury markers Cardiac Troponin T (cTnT) in vivo . This change was accompanied by an increase in inflammatory cytokines through Interleu-1β (IL-1β), Tumor Necrosis Factor α (TNF-α), and Interleu-6 (IL-6). The expression of apoptosis, such as cleaved caspase-3, Bax, and Bcl-2, was also upregulated. However, these effects were reversed via treatment with cinaciguat. Additionally, cinaciguat alleviated LPS-induced cardiac inflammation and apoptosis by activating the PRKG1/CREB signaling pathway, and promoting FtMt expression. The same results were also obtained in H9C2 cardiomyocytes.

We demonstrated that cinaciguat alleviated LPS-induced cardiac dysfunction, inflammation, and apoptosis through the PRKG1/CREB/FtMt pathway, thereby protecting against LPS-induced cardiac injury. This study identified a new strategy for treating cardiac injury caused by sepsis.

Soluble guanylyl cyclase (sGC) is a well-established pharmacological target for the treatment of acute angina pectoris, pulmonary hypertension and heart failure. Histidine 105 in the heme binding pocket of sGC is a crucial residue for heme binding and natural enzyme activation by NO. It was assumed that the heme-free sGC mutants α₁/β₁H105F and α₁/β₁H105A were valuable research tools for studying NO independent sGC activators. These mutants have been used in drug screening and animal models. We confirm that the first generation of sGC activators cinaciguat and BAY 60-2770 activate the α₁/β₁H105F and α₁/β₁H105A mutants. In contrast, we show that the second generation sGC activators runcaciguat and BAY 543 only activate heme-free sGC when the β₁H105 residue is present. By testing runcaciguat in β₁ H105F knock-in mice, we confirm this histidine-dependency in vivo. We propose a novel classification of sGC activators, distinguishing between the histidine-dependent activators runcaciguat and BAY 543 and the histidine-independent activators cinaciguat, BAY 60-2770 and BI703704. The histidine-dependency of some of the sGC activators provides a compelling rationale for a re-evaluation of previous research and drug development programs based on sGC histidine mutants. Whether the classification of sGC activators based on the activation mechanism also makes a therapeutic difference needs to be clarified in the future.