microvascular-perfusion-monitored-laser-speckle-contrast-imaging

Microvascular Perfusion Monitored by Laser Speckle Contrast Imaging during Renal Ischemia-Reperfusion Injury in Mice

Laser speckle contrast imaging (LSCI) is a non-invasive technique for measuring superficial blood perfusion over large areas. With its high spatiotemporal ...

Shantou University Medical College

Endothelial dysfunction, which leads to ischemic events under atherosclerotic conditions, can be attenuated by antagonizing the thromboxane-prostanoid receptor (TP) that mediates the vasoconstrictor effect of prostanoids including prostacyclin (PGI). This study aimed to determine whether antagonizing the E prostanoid receptor-3 (EP3; which can also be activated by PGI) adds to the above effect of TP deficiency (TP) under atherosclerotic conditions and if so, the underlying mechanism(s). Atherosclerosis was induced in ApoE mice and those with ApoE and TP. Here, we show that in phenylephrine pre-contracted abdominal aortic rings with atherosclerotic lesions of ApoE/TP mice, although an increase of force (which was larger than that of non-atherosclerotic controls) evoked by the endothelial muscarinic agonist acetylcholine to blunt the concurrently activated relaxation in ApoE counterparts was largely removed, the relaxation evoked by the agonist was still smaller than that of non-atherosclerotic TP mice. EP3 antagonism not only increased the above relaxation, but also reversed the contractile response evoked by acetylcholine in NO synthase-inhibited atherosclerotic ApoE/TP rings into a relaxation sensitive to I prostanoid receptor antagonism. In ApoE atherosclerotic vessels the expression of endothelial NO synthase was decreased, yet the production of PGI (which evokes contraction via both TP and EP3) evoked by acetylcholine was unaltered compared to non-atherosclerotic conditions. These results demonstrate that EP3 blockade adds to the effect of TP in uncovering the dilator action of natively produced PGI to alleviate endothelial dysfunction in atherosclerotic conditions.

EP3 Blockade Adds to the Effect of TP Deficiency in Alleviating Endothelial Dysfunction in Atherosclerotic Mouse Aortas.

Although recognized to have an in vivo vasodepressor effect blunted by the vasoconstrictor effect of E-prostanoid receptor-3 (EP3), prostaglandin E (PGE ) evokes contractions of many vascular beds that are sensitive to antagonizing the thromboxane prostanoid receptor (TP). This study aimed to determine the direct effect of PGE on renal arteries and/or the whole renal vasculature and how each of these two receptors is involved in the responses. Experiments were performed on isolated vessels and perfused kidneys of wild-type mice and/or mice with deficiency in TP (TP ), EP3 (EP3 ), or both TP and EP3 (TP /EP3 ). Here we show that PGE (0.001-30 μM) evoked not only contraction of main renal arteries, but also a decrease of flow in perfused kidneys. EP3 diminished the response to 0.001-0.3 μM PGE , while TP reduced that to the prostanoid of higher concentrations. In TP /EP3 vessels and perfused kidneys, PGE did not evoke contraction but instead resulted in vasodilator responses. These results demonstrate that PGE functions as an overall direct vasoconstrictor of the mouse renal vasculature with an effect reflecting the vasoconstrictor activities outweighing that of dilation. Also, our results suggest that EP3 dominates the vasoconstrictor effect of PGE of low concentrations (≤0.001-0.3 μM), but its effect is further added by that of TP, which has a higher efficacy, although activated by higher concentrations (from 0.01 μM) of the same prostanoid PGE .

Prostaglandin E sequentially activates E-prostanoid receptor-3 and thromboxane prostanoid receptor to evoke contraction and increase in resistance of the mouse renal vasculature.

Diabetic nephropathy (DN), one of the main causes of end-stage renal disease, still remains as a challenge of clinical management. This study aimed to determine whether deficiency of the thromboxane (TX) prostanoid receptor (TP), which mediates the contractile activities of all prostanoids, alleviates the development of DN and if so, to examine the underlying mechanism(s). Diabetes was induced by high fat diet and streptozotocin injection in wild-type (WT) mice and those with TP deficiency (TP). Here we show that WT and TP mice developed diabetes with a similar blood glucose level; however, signs of renal functional impairments and pathologies occurred to a lesser extent in TP than in WT mice. Also, the extent of an increase in the expression level of transforming growth factor-β1 (TGF-β1), a common pathological mediator of DN, in diabetic renal cortexes of TP mice was lower than that of WT counterparts. Moreover, we noted that expression levels of cyclooxygenase (COX)-2 and calcium-dependent phospholipase A (cPLA) as well as levels of prostaglandin E and TXA in diabetic renal cortexes were increased as compared to those of non-diabetic conditions. These results thus demonstrate that possibly due to up-regulated cPLA and COX-2 that lead to increased prostanoid syntheses in diabetic renal cortexes, TP alleviates DN development. In addition, our results suggest that such an effect of TP might be related to the suppression of TGF-β1 up-regulation that is commonly associated with the disease condition.

Effects of thromboxane prostanoid receptor deficiency on diabetic nephropathy induced by high fat diet and streptozotocin in mice.

The F prostanoid receptor (FP), which accounts for the therapeutic effect of PGF in uterine atony that leads to postpartum hemorrhage and maternal morbidity, could possibly mediate vasoconstrictor effect in small or resistance arteries to elevate blood pressure that limits the clinical use of the agent in patients with cardiovascular disorders. This study aimed to test the above hypothesis with genetically altered mice. Ex vivo and in vivo experiments were performed on control wild-type (WT) mice and mice with deficiencies in FP (FP ) or thromboxane (Tx)-prostanoid receptor (the original receptor of TxA ; TP ), and/or those with an additional deficiency in E prostanoid receptor-3 (one of the vasoconstrictor receptors of PGE ; EP3 ). Here, we show that PGF indeed evoked vasoconstrictor responses in the above-mentioned tissues of WT mice, which were however unaltered by FP . Interestingly, such contractile responses were reversed into dilations by TP /EP3 . A similar pattern of results was observed with the pressor effect of PGF under in vivo conditions. However, TP alone (which could largely remove the contractile responses) did not result in relaxation to PGF . Also, either the ex vivo vasodilator effect or the in vivo depressor response of PGF obtained after the removal of TP and EP3-mediated actions was unaltered by FP . Therefore, both the ex vivo vasoconstrictor action in small or resistance arteries and the systemic pressor effect of PGF can reflect vasoconstrictor activities derived from the non-FP receptors TP and EP3 outweighing a concurrently activated dilator effect, which is again independent of FP.

Prostaglandin F evokes vasoconstrictor and vasodepressor activities that are both independent of the F prostanoid receptor.

Necroinflammation plays an important role in disease settings such as acute kidney injury (AKI). We and others have elucidated that prostaglandins, which are critically involved in inflammation, may activate E-prostanoid 3 receptor (EP3) at low concentrations. However, how EP3 blockade interacts with regulated cell death and affects AKI remains unknown. In this study, AKI was induced by ischemia-reperfusion (30 minutes/24 hours) in Ep3 knockout (Ep3-/-), bone marrow chimeric, myeloid conditional EP3 knockout and corresponding control mice. The production of prostaglandins E2 and I2 was markedly increased after ischemia-reperfusion, and either abrogation or antagonism of EP3 ameliorated the injury. EP3 deficiency curbed inflammatory cytokine release, neutrophil infiltration and serum high-mobility group box 1 levels, but additional TLR4 inhibition with TAK-242 did not offer further protection against the injury and inflammation. The protection of Ep3-/- was predominantly mediated by suppressing Mixed Lineage Kinase domain-Like-dependent necroptosis, resulting from the inhibition of cytokine generation and the switching of cell death modality from necroptosis to apoptosis through caspase-8 up-regulation, in part due to the restraint of IL-6/JAK2/STAT3 signaling. EP3 deficiency failed to further alleviate the injury when necroptosis was inhibited. Ep3-/- in bone marrow-derived cells, particularly that in myeloid cells, protected kidneys to the same extent as that of global EP3 deletion. Thus, our results demonstrate that EP3 deficiency especially that on myeloid cells, ameliorates ischemic AKI via curbing inflammation and breaking the auto-amplification loop of necroinflammation. Hence, EP3 may be a promising target for the prevention and/or treatment of AKI.

E-prostanoid 3 receptor deficiency on myeloid cells protects against ischemic acute kidney injury via breaking the auto-amplification loop of necroinflammation.

Prostaglandin (PG) D, a commonly considered vasodilator through D prostanoid receptor-1 (DP1), might also evoke vasoconstriction via acting on the thromboxane (Tx)-prostanoid receptor (the original receptor of TxA; TP) and/or E prostanoid receptor-3 (one of the vasoconstrictor receptors of PGE; EP3). This study aimed to test the above hypothesis in the mouse renal vascular bed (main renal arteries and perfused kidneys) and/or mesenteric resistance arteries and determine how the vasoconstrictor mechanism influences the overall PGD effect on systemic blood pressure under in vivo conditions. Experiments were performed on control wild-type (WT) mice and mice with deficiencies in TP (TP) and/or EP3 (EP3). Here we show that PGD indeed evoked vasoconstrictor responses in the above-mentioned tissues of WT mice, which were however not only reduced by TP or EP3, but also reversed by TP/EP3 in some of the above tissues (mesenteric resistance arteries or perfused kidneys) to dilator reactions that were reduced by non-selective DP antagonism. A slight or mild pressor response was also observed with PGD under in vivo conditions, and this was again reversed to a depressor response in TP or TP/EP3 mice. Non-selective DP antagonism reduced the PGD-evoked depressor response in TP/EP3 mice as well. These results thus demonstrate that like other PGs, PGD activates TP and/or EP3 to evoke vasoconstrictor activities, which can outweigh its concurrent vasodepressor activity mediated mainly through DP1, and hence result in a pressor response, although the response might only be of a slight or mild extent.

The vasoconstrictor activities of prostaglandin D via the thromboxane prostanoid receptor and E prostanoid receptor-3 outweigh its concurrent vasodepressor effect mainly through D prostanoid receptor-1 ex vivo and in vivo.

Article	Year
EP3 Blockade Adds to the Effect of TP Deficiency in Alleviating Endothelial Dysfunction in Atherosclerotic Mouse Aortas. Frontiers in physiology\| PubMed ID: 31611817	2019
Prostaglandin E sequentially activates E-prostanoid receptor-3 and thromboxane prostanoid receptor to evoke contraction and increase in resistance of the mouse renal vasculature. FASEB journal : official publication of the Federation of American Societies for Experimental Biology\| PubMed ID: 31908041	2020
Effects of thromboxane prostanoid receptor deficiency on diabetic nephropathy induced by high fat diet and streptozotocin in mice. European journal of pharmacology\| PubMed ID: 32553735	2020
Prostaglandin F evokes vasoconstrictor and vasodepressor activities that are both independent of the F prostanoid receptor. FASEB journal : official publication of the Federation of American Societies for Experimental Biology\| PubMed ID: 35349198	2022
E-prostanoid 3 receptor deficiency on myeloid cells protects against ischemic acute kidney injury via breaking the auto-amplification loop of necroinflammation. Kidney international\| PubMed ID: 36087809	2023
The vasoconstrictor activities of prostaglandin D via the thromboxane prostanoid receptor and E prostanoid receptor-3 outweigh its concurrent vasodepressor effect mainly through D prostanoid... European journal of pharmacology\| PubMed ID: 37543159	2023

Jinwei Guo

Biography

JoVE Journal Publications

Other Publications