Establishing novel prostacyclin-synthesizing cells with therapeutic potential against heart diseases

Potential Effect of the Circadian Clock on Erectile Dysfunction

The circadian rhythm is an internal timing system, which is generated by circadian clock genes. Because the circadian rhythm regulates numerous cellular, behavioral, and physiological processes, organisms have evolved with intrinsic biological rhythms to adapt the daily environmental changes. A variety of pathological events occur at specific times, while disturbed rhythms can lead to metabolic syndrome, vascular dysfunction, inflammatory disorders, and cancer. Therefore, the circadian clock is considered closely related to various diseases. Recently, accumulated data have shown that the penis is regulated by the circadian clock, while erectile function is impaired by an altered sleep-wake cycle. The circadian rhythm appears to be a novel therapeutic target for preventing and managing erectile dysfunction (ED), although research is still progressing. In this review, we briefly summarize the superficial interactions between the circadian clock and erectile function, while focusing on how disturbed rhythms contribute to risk factors of ED. These risk factors include NO/cGMP pathway, atherosclerosis, diabetes mellitus, lipid abnormalities, testosterone deficiency, as well as dysfunction of endothelial and smooth muscle cells. On the basis of recent findings, we discuss the potential role of the circadian clock for future therapeutic strategies on ED, although further relevant research needs to be performed.

Differential expression of microRNA and arachidonic acid metabolism in aspirin-treated human cardiac and peri-cardiac fat-derived mesenchymal stem cells

Aspirin is a widely used drug with anti-coagulating and anti-inflammatory effects on atherosclerotic vascular disease. The goal of this study was to investigate expression of microRNA (miR) in association with changes in arachidonic acid (AA) metabolism in cardiac and surrounding fat mesenchymal stem cells (MSCs) treated with or without aspirin. Aspirin-targeted endogenous lipid metabolites that impact specific miRNA expression were examined by mass spectrometry. The pattern of miR expression was characterized using a microarray of 1100 miRs. There were a dozen miRs expressed differentially in MSCs from human myocardium and peri-myocardial fat tissue at baseline, including hsa-miR-1307-3p, 765, 4739, 3613-3p, 4281, 6816-5p, 2861, and 146b-5p. After exposure to aspirin, cardiac MSCs expressed an array of of miRs (eg, hsa-miR-4734, 10a-5p, 4267, 3197, and 3182), while generation of their endogenous AA metabolites was depressed. However, in the peri-cardiac adipose tissue-derived MSCs, treatment with the same doses of aspirin caused mild changes in the miR expression levels. In conclusion, MSCs from human myocardium and peri-myocardial fat tissue respond differentially to aspirin treatment by alterations in miR expression and AA metabolism. The study further raises an intriguing issue as to whether the copious amounts of aspirin taken worldwide by patients with cardiovascular disease may have direct impacts on their heart repair processes by regulation of stromal cell miR expression and AA metabolism.

A novel single-chain enzyme complex with chain reaction properties rapidly producing thromboxane A2 and exhibiting powerful anti-bleeding functions

Uncontrollable bleeding is still a worldwide killer. In this study, we aimed to investigate a novel approach to exhibit effective haemostatic properties, which could possibly save lives in various bleeding emergencies. According to the structure-based enzymatic design, we have engineered a novel single-chain hybrid enzyme complex (SCHEC), COX-1-10aa-TXAS. We linked the C-terminus of cyclooxygenase-1 (COX-1) to the N-terminus of the thromboxane A2 (TXA2 ) synthase (TXAS), through a 10-amino acid residue linker. This recombinant COX-1-10aa-TXAS can effectively pass COX-1-derived intermediate prostaglandin (PG) H2 (PGH2 ) to the active site of TXAS, resulting in an effective chain reaction property to produce the haemostatic prostanoid, TXA2 , rapidly. Advantageously, COX-1-10aa-TXAS constrains the production of other pro-bleeding prostanoids, such as prostacyclin (PGI2 ) and prostaglandin E2 (PGE2 ), through reducing the common substrate, PGH2 being passed to synthases which produce aforementioned prostanoids. Therefore, based on these multiple properties, this novel COX-1-10aa-TXAS indicated a powerful anti-bleeding ability, which could be used to treat a variety of bleeding situations and could even be useful for bleeding prone situations, including nonsteroidal anti-inflammatory drugs (NSAIDs)-resulted TXA2 -deficient and PGI2 -mediated bleeding disorders. This novel SCHEC has a great potential to be developed into a biological haemostatic agent to treat severe haemorrhage emergencies, which will prevent the complications of blood loss and save lives.

Association between use of aspirin or non-aspirin non-steroidal anti-inflammatory drugs and erectile dysfunction: A systematic review

OBJECTIVE

There are various etiologies of erectile dysfunction (ED), including endothelial dysfunction, atherosclerosis, and chronic inflammation. Aspirin has a protective role against endothelial dysfunction and atherosclerosis, whease all non-steroidal anti-inflammatory drugs (NSAIDs) are known for their anti-inflammatory properties. However, association between the use of aspirin or non-aspirin NSAIDs and ED is controversial. Therefore, we reviewed this relationship.

METHODS

We systematically reviewed the pathophysiology of ED, physiological effect of prostaglandins, pharmacological action of NSAIDs, and clinical and basic research studies that evaluated the effect of aspirin or non-aspirin NSAIDs on ED.

RESULTS

The research studies that assessed association between aspirin or non-aspirin NSAIDs are limited, and only 12 articles have been published. One clinical and three basic studies have claimed that aspirin or non-aspirin NSAIDs are beneficial for ED by preserving nitric oxide synthase impairment or penile blood hypercoagulability. One basic and two clinical studies considered them as risk factors because they interfered with prostaglandin production. By contrast, four clinical studies showed irrelevant results after controlling various medical indications. In addition, the mechanical effect of aspirin or non-aspirin NSAIDs on the nitric oxide pathway is still controversial.

CONCLUSIONS

The available research studies revealed that association between aspirin or non-aspirin NSAIDs and ED is controversial. Considering the high frequency of drug use, further clinical and basic investigations should be conducted to clarify their exact relationship.

Identification of Tumorigenesis from the Specific Coupling of Cyclooxygenase-2 with Microsomal Prostaglandin E2 Synthase-1 in vivo

A newly created hybrid enzyme (COX-2-10aa-mPGES-1), which mimics the specific biosynthesis of the inflammatory PGE2 through COX-2's coupling to mPGES-1, was stably expressed in HEK293 cells. The stable cell line, which consistently expresses the superior triple catalytic (Trip-Cat) activities from COX-2 and mPGES-1, was able to directly convert arachidonic acid into the pathogenic PGE2 and distinguish it from other PGE2 synthesizing pathways, as confirmed by enzyme immunoassay, LC/MS analysis and a specific [14C]-AA (arachidonic acid) metabolite analysis approach. A competitive assay confirmed that the endogenous cPGES and mPGES-2 in the HEK293 cells had little involvement in the presence of the expressed COX-2-10aa-mPGES-1 for the synthesis of pathogenic PGE2. Furthermore, subcutaneous injection of the stable cell lines into nu/nu mice revealed 100% (10 out 10) occurrence of tumor mass formation beginning on Day 7 and a continuous progression of the masses to the maximal size which required sacrificing the mice. In contrast, only 10% occurrence of tumor masses, though smaller and with slower growth rates, were observed for the group of vector-transfected HEK293 control cells expressing only endogenous cPGES and/or mPGES-2. The PGE2 produced from multiple pathways by the HEK293 cells co-expressing the individual wild type COX-2 and mPGES-1, and in the presence of endogenous cPGES and mPGES-2, showed also a significantly increased tumor occurrence rate to 30%, which confirmed that the sole coupling of COX-2 to mPGES-1 is a powerful tumor-advancing factor. This result implies that the engineered COX-2-10aa-mPGES-1 could be a promising molecule as a drug developing target against the pathway of COX-2 coupled to mPGES-1 to treat inflammatory diseases and cancers.

Screening and identification of dietary oils and unsaturated fatty acids in inhibiting inflammatory prostaglandin E2 signaling in fat stromal cells

Background

The molecular mechanisms of dietary oils (such as fish oil) and unsaturated fatty acids, which are widely used by the public for anti-inflammation and vascular protection, have not been settled yet. In this study, prostaglandin E₂ (PGE₂)-mediated calcium signaling was used to screen dietary oils and eight unsaturated fatty acids for identification of their anti-inflammatory mechanisms. Isolated fat/stromal cells expressing endogenous PGE₂ receptors and an HEK293 cell line specifically expressing the recombinant human PGE₂ receptor subtype-1 (EP₁) were cultured and used in live cell calcium signaling assays. The different dietary oils and unsaturated fatty acids were used to affect cell signaling under the specific stimulation of a pathological amount of inflammatory PGE₂.

Results

It was identified that fish oil best inhibited the PGE₂ signaling in the primary cultured stromal cells. Second, docosahexaenoic acid (DHA), found in abundance in fish oil, was identified as a key factor of inhibition of PGE₂ signaling. Eicosapentaenoic acid (EPA), another major fatty acid found in fish oil and tested in this study was found to have small effect on EP₁ signaling. The study suggested one of the four PGE₂ subtype receptors, EP₁ as the key target for the fish oil and DHA target. These findings were further confirmed by using the recombinant EP₁ expressed in HEK293 cells as a target.

Conclusion

This study demonstrated the new mechanism behind the positive effects of dietary fish oils in inhibiting inflammation originates from the rich concentration of DHA, which can directly inhibit the inflammatory EP₁-mediated PGE₂ receptor signaling, and that the inflammatory response stimulated by PGE₂ in the fat stromal cells, which directly related to metabolic diseases, could be down regulated by fish oil and DHA. These findings also provided direct evidence to support the use of dietary oils and unsaturated fatty acids for protection against heart disease, pain, and cancer resulted from inflammatory PGE_2.