Mariagrazia Ruvoletto

Glioblastoma multiforme is the most aggressive primary brain tumor in adults, which displays extremely poor prognosis. Protease-activated receptor 2 (PAR2) and its downstream effector SerpinB3 are overexpressed in aggressive glioblastomas. In this study we evaluated the antitumor activity of 1-piperidine propionic acid (1-PPA), an allosteric PAR2 inhibitor, in in vitro preclinical models of glioblastoma. PAR2 and SerpinB3 were analyzed at the transcriptional and protein level in glioblastoma cell lines and primary cultures. These were treated with 1-PPA alone or in association with temozolomide (TMZ) and the effects evaluated by Incucyte^® technology. Pharmacokinetics and tissue distribution of 1-PPA were assessed in mice by LC-MS/MS. 1-PPA significantly reduced glioma cell proliferation, migration, and invasion, thus promoting apoptotic cell death, in a concentration-dependent manner. The combined treatment with TMZ led to a concentration-dependent decrease in cell proliferation (12–20%) compared to TMZ alone. Molecularly, 1-PPA downregulated PAR2 and SerpinB3 expression. Pharmacokinetic studies in healthy mice showed that 1-PPA is systemically bioavailable and distributes to several organs, including the brain. These data indicate that 1-PPA shows brain exposure and capability to affect different hallmarks of aggressiveness in glioblastoma cells, including hyperproliferation and invasion, supporting its further development as a novel therapeutic strategy in these tumors.

Sepsis is a complex disorder caused by a dysregulated host response to infection, with high levels of morbidity and mortality. Treatment aimed to modulate immune response and maintain vascular function is still one of the major clinical challenges. This study was designed to test the effect of the small molecule 1-Piperidine Propionic Acid (1-PPA) as molecular targeted agent to block protease-activated receptor 2 (PAR2), one of the major modulators of inflammatory response in LPS-induced experimental endotoxemia. In the THP-1 cell line, LPS-induced cytokine expression was inhibited by 1-PPA in a dose-dependent manner. In LPS-injected mice, treatment with 1-PPA was effective in reducing mortality and sepsis-related symptoms and improved cardiac function parameters. After 6 h from LPS injection, a significant decrease in IL-6, IL-1β, and IL-10 was observed in the lung tissue of 1-PPA-treated mice, compared to controls. In these mice, a significant decrease in vasoactive molecules, especially kininogen-1, was also observed, mainly in the liver. Histopathological analysis confirmed typical features of sepsis in different organs and these findings were markedly reduced in mice treated with 1-PPA. These data demonstrate the effectiveness of 1-PPA in protecting the whole organism from sepsis-induced damage.

In Parkinson’s disease, neuroinflammation is a double-edged sword; when inflammation occurs it can have harmful effects, despite its important role in battling infections and healing tissue. Once triggered by microglia, astrocytes acquire a reactive state and shift from supporting the survival of neurons to causing their destruction. Activated microglia and Proteinase-activated receptor-2 (PAR2) are key points in the regulation of neuroinflammation. 1-Piperidin Propionic Acid (1-PPA) has been recently described as a novel inhibitor of PAR2. The aim of our study was to evaluate the effect of 1-PPA in neuroinflammation and microglial activation in Parkinson’s disease. Protein aggregates and PAR2 expression were analyzed using Thioflavin S assay and immunofluorescence in cultured human fibroblasts from Parkinson’s patients, treated or untreated with 1-PPA. A significant decrease in amyloid aggregates was observed after 1-PPA treatment in all patients. A parallel decrease in PAR2 expression, which was higher in sporadic Parkinson’s patients, was also observed both at the transcriptional and protein level. In addition, in mouse LPS-activated microglia, the inflammatory profile was significantly downregulated after 1-PPA treatment, with a remarkable decrease in IL-1β, IL-6, and TNF-α, together with a decreased expression of PAR2. In conclusion, 1-PPA determines the reduction in neuroglia inflammation and amyloid aggregates formation, suggesting that the pharmacological inhibition of PAR2 could be proposed as a novel strategy to control neuroinflammation.

In Parkinson's disease, neuroinflammation is a complex defense mechanism. Activated microglia and Proteinase-activated receptor-2 (PAR2) are key points in the regulation of neuroinflammation. 1-Piperidin Propionic Acid (1-PPA) has been recently described as a novel inhibitor of PAR2. The aim of our study was to evaluate the effect of 1-PPA in neuroinflammation and microglial activation in Parkinson's disease. Protein aggregates and PAR2 expression were analyzed by thioflavin S assay and immunofluorescence in cultured human fibroblasts from Parkinson's patients, treated or not with 1-PPA. A significant decrease of amyloid aggregates and expression of PAR2 were observed after 1-PPA treatment in all patients. A parallel decrease of PAR2 expression, that was higher in sporadic Parkinson’s patients, was also observed both at transcriptional and protein level. In addition, in mouse LPS-activated microglia, the inflammatory profile was significantly downregulated after 1-PPA treatment, with a remarkable decrease of IL-1, IL-6 and TNF-togheter with PAR2 decreased expression.In conclusion, 1-PPA determines reduced neuroglia inflammation and amyloid aggregates formation, suggesting that pharmacological inhibition of PAR2 could be proposed as a novel strategy to control neuroinflammation.

Summary: Background: SerpinB3 is a cysteine protease inhibitor involved in liver disease progression due to its proinflammatory and profibrogenic properties. The polymorphic variant SerpinB3‐PD (SB3‐PD), presents a substitution in its reactive centre loop, determining the gain of function.Aims: To disclose the clinical characteristics of a cohort of patients with cirrhosis in relation to the presence of SB3‐PD and to assess the effect of this genetic variant on fibrogenic and inflammatory cytokines in vitro.Methods: We assessed SB3 polymorphism in 90 patients with cirrhosis, prospectively followed up in our referral centre. We used HepG2 and HuH‐7 cells transfected to overexpress either wild‐type SB3 (SB3‐WT) or SB3‐PD to assess their endogenous effect, while LX2 and THP‐1 cells were treated with exogenous SB3‐WT or SB3‐PD proteins.Results: Patients carrying SB3‐PD had more severe portal hypertension and higher MELD scores, than patients carrying SB3‐WT. In multivariate analysis, SB3‐PD was an independent predictor of cirrhosis complications. Patients with SB3‐PD polymorphism presented with more severe liver fibrosis and inflammatory features. Hepatoma cells overexpressing SB3‐PD showed higher TGF‐β1 expression than controls. The addition of recombinant SB3‐PD induced an up‐regulation of TGF‐β1 in LX2 cells and a more prominent inflammatory profile in THP‐1 cells, compared to the effect of SB3‐WT protein.Conclusions: The polymorphic variant SB3‐PD is highly effective in determining activation of TGF‐β1 and inflammation in vitro. Patients with cirrhosis who carry SB3‐PD polymorphism may be more prone to develop severe liver disease progression. However, further validation studies are warranted to support the in vivo relevance of this polymorphism.

In the last decades, studies on the inflammatory signaling pathways in multiple pathological contexts have revealed new targets for novel therapies. Among the family of G-protein-coupled Proteases Activated Receptors, PAR2 was identified as a driver of the inflammatory cascade in many pathologies, ranging from autoimmune disease to cancer metastasis. For this reason, many efforts have been focused on the development of potential antagonists of PAR2 activity. This work focuses on a small molecule, 1-Piperidine Propionic Acid (1-PPA), previously described to be active against inflammatory processes, but whose target is still unknown. Stabilization effects observed by cellular thermal shift assay coupled to in-silico investigations, including molecular docking and molecular dynamics simulations, suggested that 1-PPA binds PAR2 in an allosteric pocket of the receptor inactive conformation. Functional studies revealed the antagonist effects on MAPKs signaling and on platelet aggregation, processes mediated by PAR family members, including PAR2. Since the allosteric pocket binding 1-PPA is highly conserved in all the members of the PAR family, the evidence reported here suggests that 1-PPA could represent a promising new small molecule targeting PARs with antagonistic activity.

In the last decades, studies on the inflammatory signaling pathways in multiple pathological contexts revealed new targets for novel therapies. Among the family of G-protein-coupled Proteases Activated Receptors, PAR2 was identified as a driver of the inflammatory cascade in many pathologies, ranging from autoimmune disease to cancer metastasis. For this reason, many efforts have been focused on the development of potential antagonists of PAR2 activity. This work focuses on a small molecule, 1-Piperidine Propionic Acid (1-PPA), previously described to be active against inflammatory processes, but whose target is still unknown. Stabilization effects observed by cellular thermal shift assay coupled to in-silico investigations, including molecular docking and Molecular Dynamics simulations, suggested that 1-PPA binds PAR2 in an allosteric pocket of the receptor inactive conformation. In addition, this compound was found able to inhibit platelet aggregation, a process mediated by PAR family members, including PAR2. Since the allosteric pocket binding 1-PPA is highly conserved in all the members of the PAR family, the evidence reported here suggests that 1-PPA could represent a promising new small molecule targeting PARs with antagonistic activity.

Abnormal activation of the Wnt-β-catenin signaling cascade is involved in tumor growth and dissemination. SerpinB3 has been shown to induce β-catenin, and both molecules are overexpressed in tumors, particularly in those with poor prognoses. The aim of this study was to evaluate the ability of SerpinB3 to modulate the Wnt pathway in liver cancer and in monocytic cells, the main type of inflammatory cells in the tumor microenvironment. The Wnt cascade, Wnt co-receptors, and low-density lipoprotein receptor-related protein (LRP) members were analyzed in different cell lines and human monocytes in the presence or absence of SerpinB3. The Wnt-β-catenin axis was also evaluated in liver tumors induced in mice with different extents of SeprinB3 expression. In monocytic cells, SerpinB3 induced a significant upregulation of Wnt-1/7, nuclear β-catenin, and c-Myc, which are associated with increased cell lifespan and proliferation. In liver tumors in mice, the expression of β-catenin was significantly correlated with the presence of SerpinB3. In hepatoma cells, Wnt co-receptors LRP-5/6 and LRP-1, implicated in cell survival and invasiveness, were upregulated by SerpinB3. The LRP pan-inhibitor RAP not only induced a decrease in LRP expression, but also a dose–dependent reduction in SerpinB3-induced invasiveness. In conclusion, SerpinB3 determines the activation of the Wnt canonical pathway and cell invasiveness through the upregulation of LRP family members.

SerpinB3 is a serine protease inhibitor that plays a relevant role in disease progression and cancer by increasing fibrosis, cell proliferation, and invasion, besides conferring resistance to apoptosis. The mechanisms underlying these biological activities are not yet fully understood. The aim of this study was to generate antibodies directed against different SerpinB3 epitopes to better investigate their biological role. Five exposed epitopes were identified using the software DNASTAR Lasergene and the corresponding synthetic peptides were used for NZW rabbit immunization. Anti-P#2 and anti-P#4 antibodies were able to recognize both SerpinB3 and SerpinB4 by ELISA. Anti-P#5 antibody, produced against the reactive site loop of SerpinB3, showed the greatest specific reactivity for human SerpinB3. This antibody was able to recognize SerpinB3 at nuclear level, while anti-P#3 antibody recognized SerpinB3 only at cytoplasmic level, both by immunofluorescence and by immunohistochemistry. The biological activity of each antibody preparation was assessed in HepG2 cells overexpressing SerpinB3 and anti-P#5 antibody reduced proliferation by 12% cell and cell invasion by 75%, while trivial results were obtained with the other antibody preparations. These findings indicate that the reactive site loop of SerpinB3 is essential for the invasiveness features induced by this serpin and it could become a novel druggable target.

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease. NAFLD can evolve from simple fatty liver to non-alcoholic steatohepatitis (NASH), and ultimately, to cirrhosis. Inflammation and oxidative stress, promoted by mitochondrial dysfunction, play a crucial role in the onset and development of NASH. To date, no therapy has been approved for NAFLD and NASH. The aim of this study is to evaluate if the anti-inflammatory activity of acetylsalicylic acid (ASA) and the mitochondria-targeted antioxidant effect of mitoquinone could hinder the progression of non-alcoholic steatohepatitis. In mice, fatty liver was induced through the administration of a deficient in methionine and choline and rich in fat diet. Two experimental groups were treated orally with ASA or mitoquinone. Histopathologic evaluation of steatosis and inflammation was performed; the hepatic expression of genes associated with inflammation, oxidative stress, and fibrosis was evaluated; the protein expression of IL-10, cyclooxygenase 2, superoxide dismutase 1, and glutathione peroxidase 1 in the liver was analyzed; a quantitative analysis of 15-epi-lipoxin A4 in liver homogenates was performed. Mitoquinone and ASA significantly reduced liver steatosis and inflammation by decreasing the expression of TNFα, IL-6, Serpinb3, and cyclooxygenase 1 and 2 and restoring the anti-inflammatory IL-10. Treatment with mitoquinone and ASA increased the gene and protein expression of antioxidants, i.e., catalase, superoxide dismutase 1, and glutathione peroxidase 1, and decreased the expression of profibrogenic genes. ASA normalized the levels of 15-epi-Lipoxin A4. In mice fed with a deficient in methionine and choline and rich in fat diet, mitoquinone and ASA reduce steatosis and necroinflammation and may represent two effective novel strategies for the treatment of non-alcoholic steatohepatitis.