The multiple roles of lysophosphatidic acid in vascular disease and atherosclerosis

Calpain inhibition as a novel therapeutic strategy for aortic dissection with acute lower extremity ischemia

BACKGROUND

Aortic dissection (AD) patients with malperfusion present significant challenges and are associated with high postoperative mortality rates. Limited data exist regarding the management of patients with AD and acute lower extremity ischemia. Early diagnosis of the extent of malperfusion and timely intervention are critical for improving patient prognosis.

METHODS

A total of 104 patients diagnosed with AD were enrolled in this observational retrospective study, of which 11 (10.6%) presented with lower limb ischemia (LLI). A comparative analysis was conducted on the clinical data of the AD group and the AD + LLI group. Plasma concentrations of SBDP145, a specific indicator of Calpain activity, were quantified in Control, AD, and AD + LLI groups using ELISA. To explore the role of Calpain in LLI and AD, pharmacological inhibition with Calpeptin and transgenic mice overexpressing calpastatin (Tg-CAST) were utilized in mouse models. RNA sequencing and functional assays were employed to identify the downstream effectors of Calpain.

RESULTS

Patients in the AD + LLI group exhibited significantly elevated leukocyte counts, percentages of neutrophils and lymphocytes, as well as increased serum levels of AST, creatinine, total cholesterol, low-density lipoprotein, uric acid, and creatine kinase compared to those in the AD group. Furthermore, the mean calcium ion concentration and Ca2+-dependent Calpain activation were significantly higher in the AD + LLI patients. Both endogenous and exogenous Calpain inhibitors effectively promoted the restoration of blood flow to ischemic hind limbs by inhibiting the inflammatory response and promoting vascular regeneration. Additionally, Calpain inhibition prevented the onset and progression of AD. RNA sequencing and Western Blot assays demonstrated that Calpain inhibition significantly increased levels of Fabp3, which is involved in the ischemia-induced fatty acid metabolism pathway.

CONCLUSIONS

Inhibition of Calpain has been demonstrated to decrease the incidence of AD and enhance the restoration of blood flow perfusion in ischemic lower extremities. This effect may be mediated by the upregulation of Fabp3. These findings highlight the potential for targeted interventions against Calpain as a novel therapeutic strategy in the treatment of cardiovascular disease.

Glycerophospholipid and Sphingosine- 1-phosphate Metabolism in Cardiovascular Disease: Mechanisms and Therapeutic Potential

Cardiovascular disease remains a leading cause of mortality worldwide, driven by factors such as dysregulated lipid metabolism, oxidative stress, and inflammation. Recent studies highlight the critical roles of both glycerophospholipid and sphingosine- 1-phosphate metabolism in the pathogenesis of cardiovascular disorders. However, the contributions of glycerophospholipid-derived metabolites remain underappreciated. Glycerophospholipid metabolism generates bioactive molecules that contribute to endothelial dysfunction, lipid accumulation, and cardiac cell injury while also modulating inflammatory and oxidative stress responses. Meanwhile, sphingosine- 1-phosphate is a bioactive lipid mediator that regulates vascular integrity, inflammation, and cardiac remodeling through its G-protein-coupled receptors. The convergence of these pathways presents novel therapeutic opportunities, where dietary interventions such as omega- 3 polyunsaturated fatty acids and pharmacological targeting of sphingosine- 1-phosphate receptors could synergistically mitigate cardiovascular risk. This review underscores the need for further investigation into the interplay between glycerophospholipid metabolism and sphingosine- 1-phosphate signaling to advance targeted therapies for the prevention and management of cardiovascular disease.

Lysophosphatidic acid metabolism and signaling in heart disease

Lysophosphatidic acid (LPA) is a bioactive lipid that is mainly produced by the secreted lysophospholipase D, autotaxin (ATX), and signals through at least six G protein-coupled receptors (LPA1-6). Extracellular LPA is degraded through lipid phosphate phosphatases (LPP1, LPP2, and LPP3) at the plasmamembrane, terminating LPA receptor signaling. The ATX-LPA-LPP3 pathway is critically involved in a wide range of physiological processes, including cell survival, migration, proliferation, angiogenesis, and organismal development. Similarly, dysregulation of this pathway has been linked to many pathological processes, including cardiovascular disease. This review summarizes and interprets current literature examining the regulation and role of the ATX-LPA-LPP3 axis in heart disease. Specifically, the contribution of altered LPA metabolism via ATX and LPP3 and resulting changes to LPA receptor signaling in obesity cardiomyopathy, cardiac mitochondrial dysfunction, myocardial infarction/ischemia-reperfusion injury, hypertrophic cardiomyopathy, and aortic valve stenosis is discussed.

LPA-Induced Thromboxane A2-Mediated Vasoconstriction Is Limited to Poly-Unsaturated Molecular Species in Mouse Aortas

We have previously reported that, in aortic rings, 18:1 lysophosphatidic acid (LPA) can induce both vasodilation and vasoconstriction depending on the integrity of the endothelium. The predominant molecular species generated in blood serum are poly-unsaturated LPA species, yet the vascular effects of these species are largely unexplored. We aimed to compare the vasoactive effects of seven naturally occurring LPA species in order to elucidate their potential pathophysiological role in vasculopathies. Vascular tone was measured using myography, and thromboxane A2 (TXA2) release was detected by ELISA in C57Bl/6 mouse aortas. The Ca2+-responses to LPA-stimulated primary isolated endothelial cells were measured by Fluo-4 AM imaging. Our results indicate that saturated molecular species of LPA elicit no significant effect on the vascular tone of the aorta. In contrast, all 18 unsaturated carbon-containing (C18) LPAs (18:1, 18:2, 18:3) were effective, with 18:1 LPA being the most potent. However, following inhibition of cyclooxygenase (COX), these LPAs induced similar vasorelaxation, primarily indicating that the vasoconstrictor potency differed among these species. Indeed, C18 LPA evoked a similar Ca2+-signal in endothelial cells, whereas in endothelium-denuded aortas, the constrictor activity increased with the level of unsaturation, correlating with TXA2 release in intact aortas. COX inhibition abolished TXA2 release, and the C18 LPA induced vasoconstriction. In conclusion, polyunsaturated LPA have markedly increased TXA2-releasing and vasoconstrictor capacity, implying potential pathophysiological consequences in vasculopathies.

From orphan to oncogene: The role of GPR35 in cancer and immune modulation

G protein-coupled receptors (GPCRs) are well-studied and the most traceable cell surface receptors for drug discovery. One of the intriguing members of this family is G protein-coupled receptors 35 (GPR35), which belongs to the class A rhodopsin-like family of GPCRs identified over two decades ago. GPR35 presents interesting features such as ubiquitous expression and distinct isoforms. Moreover, functional and genome-wide association studies on its widespread expression have linked GPR35 with pathophysiological disease progression. Various pieces of evidence have been accumulated regarding the independent or endogenous ligand-dependent role of GPR35 in cancer progression and metastasis. In the current scenario, the relationship of this versatile receptor and its putative endogenous ligands for the activation of oncogenic signal transduction pathways at the cellular level is an active area of research. These intriguing features offered by GPR35 make it an oncological target, justifying its uniqueness at the physiological and pathophysiological levels concerning other GPCRs. For pharmacologically targeting receptor-induced signaling, few potential competitive antagonists have been discovered that offer high selectivity at a human level. In addition to its fascinating features, targeting GPR35 at rodent and human orthologue levels is distinct, thus contributing to the sub-species selectivity. Strategies to modulate these issues will help us understand and truly target GPR35 at the therapeutic level. In this article, we have provided prospects on each topic mentioned above and suggestions to overcome the challenges. This review discusses the molecular mechanism and signal transduction pathways activated by endogenous ligands or spontaneous auto-activation of GPR35 that contributes towards disease progression. Furthermore, we have highlighted the GPR35 structure, ubiquitous expression, its role in immunomodulation, and at the pathophysiological level, especially in cancer, indicating its status as a versatile receptor. Subsequently, we discussed the various proposed ligands and their mechanism of interaction with GPR35. Additionally, we have summarized the GPR35 antagonist that provides insights into the opportunities for therapeutically targeting this receptor.