Arianna Carolina Rosa

PPARγ stimulation promotes mitochondrial biogenesis and prevents glucose deprivation-induced neuronal cell loss

Peroxisome proliferator-activated receptor (PPAR)gamma stimulation provides protection in several models of neurological disorders, but the mechanisms underlying these effects remain to be fully elucidated. Here we have studied whether two PPARgamma agonists, pioglitazone and rosiglitazone, prevent loss of differentiated SH-SY5Y cells transiently exposed to glucose deprivation (GD). Nanomolar drug concentrations prevented GD-induced cell loss in a concentration- and time-dependent manner. These effects were abolished by malonate, a reversible mitochondrial Complex II inhibitor, while significantly potentiated by pyruvate, thus suggesting that they are related to mitochondrial function. During cell pretreatment, PPARgamma agonists promoted biogenesis of functional mitochondria, as indicated by the up-regulation of PPARgamma coactivator (PGC)-1alpha, NRF1, TFAM, cytochrome c oxidase subunit (CO) I and CO IV, and the increased level of mtDNA, while did not significantly change mitochondrial membrane potential. In addition, the analysis of the concentration-response and time-course curves for the protective effects and the up-regulation of mitochondrial biogenesis markers suggests that mitochondrial biogenesis and cell loss prevention are related effects. In conclusion our data indicate that a prolonged PPARgamma stimulation, by repeated administration of nanomolar pioglitazone or rosiglitazone concentrations, decreases GD-induced loss of differentiated SH-SY5Y cells. In addition, they suggest that mitochondrial biogenesis may contribute to these effects.

The role of histamine in neurogenic inflammation

The term ‘neurogenic inflammation’ has been adopted to describe the local release of inflammatory mediators, such as substance P and calcitonin gene‐related peptide, from neurons. Once released, these neuropeptides induce the release of histamine from adjacent mast cells. In turn, histamine evokes the release of substance P and calcitonin gene‐related peptide; thus, a bidirectional link between histamine and neuropeptides in neurogenic inflammation is established. The aim of this review is to summarize the most recent findings on the role of histamine in neurogenic inflammation, with particular regard to nociceptive pain, as well as neurogenic inflammation in the skin, airways and bladder.

Acute treatment with relaxin protects the kidney against ischaemia/reperfusion injury

Although recent preclinical and clinical studies have demonstrated that recombinant human relaxin (rhRLX) may have important therapeutic potential in acute heart failure and chronic kidney diseases, the effects of acute rhRLX administration against renal ischaemia/reperfusion (I/R) injury have never been investigated. Using a rat model of 1‐hr bilateral renal artery occlusion followed by 6‐hr reperfusion, we investigated the effects of rhRLX (5 μg/Kg i.v.) given both at the beginning and after 3 hrs of reperfusion. Acute rhRLX administration attenuated the functional renal injury (increase in serum urea and creatinine), glomerular dysfunction (decrease in creatinine clearance) and tubular dysfunction (increase in urinary excretion of N‐acetyl‐β‐glucosaminidase) evoked by renal I/R. These beneficial effects were accompanied by a significant reduction in local lipid peroxidation, free radical‐induced DNA damage and increase in the expression/activity of the endogenous antioxidant enzymes Mn‐ and CuZn‐superoxide dismutases (SOD). Furthermore, rhRLX administration attenuated the increase in leucocyte activation, as suggested by inhibition of myeloperoxidase activity, intercellular‐adhesion‐molecule‐1 expression, interleukin (IL)‐1β, IL‐18 and tumour necrosis factor‐α production as well as increase in IL‐10 production. Interestingly, the reduced oxidative stress status and neutrophil activation here reported were associated with rhRLX‐induced activation of endothelial nitric oxide synthase and up‐regulation of inducible nitric oxide synthase, possibly secondary to activation of Akt and the extracellular signal‐regulated protein kinase (ERK) 1/2, respectively. Thus, we report herein that rhRLX protects the kidney against I/R injury by a mechanism that involves changes in nitric oxide signalling pathway.

Celecoxib decreases expression of the adhesion molecules ICAM‐1 and VCAM‐1 in a colon cancer cell line (HT29)

We investigated the ability of celecoxib, a selective cyclooxygenase‐2 (COX‐2) inhibitor, to modulate expression of ICAM‐1 and VCAM‐1 in the colon cancer cell line HT29.

Peroxisome proliferator-activated receptor β/δ agonism protects the kidney against ischemia/reperfusion injury in diabetic rats

Diabetes is an important risk factor for ischemic acute kidney injury, whose pharmacological treatment remains an unmet medical need. The peroxisome proliferator-activated receptor (PPAR) β/δ is highly expressed in the kidney, although its role has not yet been elucidated. Here, we used an in vivo model of renal ischemia/reperfusion (I/R) in streptozotocin-induced diabetic rats (i) to evaluate whether diabetes increases kidney susceptibility to I/R injury and (ii) to investigate the effects of PPARβ/δ activation. The degree of renal injury (1h ischemia/6h reperfusion) was significantly increased in diabetic rats compared with nondiabetic littermates. PPARβ/δ expression was increased after I/R, with the highest levels in diabetic rats. Administration of the selective PPARβ/δ agonist GW0742 attenuated the renal dysfunction, leukocyte infiltration, and formation of interleukin-6 and tumor necrosis factor-α. These effects were accompanied by an increased expression of the suppressor of cytokine signaling (SOCS)-3, which plays a critical role in the cytokine-activated signaling pathway. The beneficial effects of GW0742 were attenuated by the selective PPARβ/δ antagonist GSK0660. Thus, we report herein that PPARβ/δ activation protects the diabetic kidney against I/R injury by a mechanism that may involve changes in renal expression of SOCS-3 resulting in a reduced local inflammatory response.

Substance P-induced cyclooxygenase-2 expression in human umbilical vein endothelial cells

Substance P (SP) is a neuropeptide involved in neurogenic inflammation and an agonist for NK1, NK2, and NK3 receptors. SP induces prostaglandin (PG) production in various cell types, and these eicosanoids are responsible for numerous inflammatory and vascular effects. Cyclooxygenase (COX) are needed to convert arachidonic acid to PGs. The study evaluated the effect of SP on COX expression in human umbilical vein endothelial cells (HUVEC). COX‐2 protein expression was upregulated by SP with a peak at 100 nM and at 20 h; in the same experimental conditions COX‐1 protein expression was unchanged. A correlation between COX‐2 expression and PGI2 and PGE2 release was detected. Dexamethasone (DEX) inhibited SP‐mediated COX‐2 expression. Mitogen‐activated protein kinases (MAPK) p38 and p42/44 were activated by SP, whereas SB202190 and PD98059, inhibitors of these kinases, blocked COX‐2 expression. 5,5‐dimethyl‐3‐(3‐fluorophenyl)‐4‐(4‐methylsulphonyl)phenyl‐2(5H)‐furanone (DFU), an experimental selective COX‐2 inhibitor, blocked SP‐induced PG release. By RT–PCR and Western blot analysis, we demonstrated that NK1 and NK2 but not NK3 receptors are present on HUVEC. Selective NK1 and NK2 agonists, namely [Sar9, Met(O2)11]SP and [β‐Ala8] NKA(4–10), upregulated COX‐2 protein expression and PG production, whereas senktide (Suc–Asp–Phe–MePhe–Gly–Leu–Met–NH2), a selective NK3 agonist, was ineffective in this respect. The NK1 selective antagonist L703,606 ((cis)‐2‐(diphenylmethyl)‐N‐((2‐iodophenyl)‐methyl)‐1‐azabicyclo(2.2.2)octan‐3‐amine) and the NK2 selective antagonist SR 48,968 ((S)‐N‐methyl‐N‐(4‐(4‐acetylamino‐4‐phenylpiperidino)‐2‐(3,4 dichlorophenyl)butyl) benzamide) competitively antagonised SP‐induced effects. The study shows HUVEC to possess functional NK1 and NK2 receptors, which mediate the ability of SP to induce expression of COX‐2 in HUVEC, thus showing a previously‐undetected effect of SP on endothelial cells.

The subtypes of peroxisome proliferator‐activated receptors expressed by human podocytes and their role in decreasing podocyte injury

BACKGROUND AND PURPOSE Peroxisome proliferator‐activated receptors (PPARs) are ligand‐activated transcription factors, and three subtypes (α, β and γ) have been identified. PPAR activation has been reported to decrease renal injury and markers of glomerular dysfunction in models of renal ischemia/reperfusion (I/R). However, both the I/R effects and the effects of PPAR agonists on podocytes, an integral cellular part of the glomerular filtration barrier, remain to be established.

PPARγ stimulation promotes neurite outgrowth in SH-SY5Y human neuroblastoma cells

Several evidences indicate that PPARgamma stimulation promotes neuronal differentiation. However, to date, no data describe the effects of PPARgamma agonists on neurite outgrowth. Here we have evaluated the effects of pioglitazone, a synthetic PPARgamma agonist, on differentiation and neurite outgrowth in SH-SY5Y human neuroblastoma cells. Our results show that pioglitazone promotes cell differentiation and the outgrowth of cell processes in a concentration-dependent manner with the maximal effect at 100 nM-1 microM. It significantly increases both the mean process length and the percentage of neurite-bearing cells. In addition, these effects are accompanied by significant activation of p42 and p44 mitogen-activated protein kinases. In conclusion, albeit preliminary, these findings suggest the possibility that PPARgamma stimulation may contribute to the development and maintenance of a proper neuronal connectivity within neuronal networks.

Celecoxib modulates adhesion of HT29 colon cancer cells to vascular endothelial cells by inhibiting ICAM-1 and VCAM-1 expression

Cyclooxygenase‐2 (COX‐2) is highly expressed during inflammation and can promote the progression of colorectal cancer. Interactions between cancer cells and vascular endothelial cells are key events in this process. Recently, the selective COX‐2 inhibitor, celecoxib, was shown to inhibit expression of the adhesion molecules, ICAM‐1 and VCAM‐1, in the human colon cancer cell line HT29 and to inhibit adhesion of HT29 cells to FCS‐coated plastic wells. Here, we evaluated the effects of celecoxib on adhesion of HT29 cells to human umbilical vein endothelial cells (HUVEC), mediated by ICAM‐1 and VCAM‐1, to assess further the potential protective effects of celecoxib on cancer development.

Cholesteryl butyrate solid lipid nanoparticles inhibit the adhesion and migration of colon cancer cells

BACKGROUND AND PURPOSE Cholesteryl butyrate solid lipid nanoparticles (cholbut SLN) provide a delivery system for the anti‐cancer drug butyrate. These SLN inhibit the adhesion of polymorphonuclear cells to the endothelium and may act as anti‐inflammatory agents. As cancer cell adhesion to endothelium is crucial for metastasis dissemination, here we have evaluated the effect of cholbut SLN on adhesion and migration of cancer cells.