Expression of Septin4 in Schistosoma japonicum-infected mouse livers after praziquantel treatment

Deacetylation of Septin4 by SIRT2 (Silent Mating Type Information Regulation 2 Homolog-2) Mitigates Damaging of Hypertensive Nephropathy

BACKGROUND

Hypertension can lead to podocyte damage and subsequent apoptosis, eventually resulting in glomerulosclerosis. Although alleviating podocyte apoptosis has clinical significance for the treatment of hypertensive nephropathy, an effective therapeutic target has not yet been identified. The function of septin4, a proapoptotic protein and an important marker of organ damage, is regulated by post-translational modification. However, the exact role of septin4 in regulating podocyte apoptosis and its connection to hypertensive renal damage remains unclear.

METHODS

We investigated the function and mechanism of septin4 in hypertensive nephropathy to discover a theoretical basis for targeted treatment. Mouse models including Rosa 26 (Gt(ROSA)26Sor)-SIRT2 (silent mating type information regulation 2 homolog-2)-Flag-TG (transgenic) (SIRT2-TG) mice SIRT2-knockout, and septin4-K174Q mutant mice, combined with proteomic and acetyl proteomics analysis, followed by multiple molecular biological methodologies, were used to demonstrate mechanisms of SIRT2-mediated deacetylation of septin4-K174 in hypertensive nephropathy.

RESULTS

Using transgenic septin4-K174Q mutant mice treated with the antioxidant Tempol, we found that hyperacetylation of the K174 site of septin4 exacerbates Ang II (angiotensin II)- induced hypertensive renal injury resulting from oxidative stress. Proteomics and Western blotting assays indicated that septin4-K174Q activates the cleaved-PARP1 (poly [ADP-ribose] polymerase family, member 1)-cleaved-caspase3 pathway. In septin4-knockdown human renal podocytes, septin4-K174R, which mimics deacetylation at K174, rescues podocyte apoptosis induced by Ang II. Immunoprecipitation and mass spectrometry analyses identified SIRT2 as a deacetylase that interacts with the septin4 GTPase domain and deacetylates septin4-K174. In Sirt2-deficient mice and SIRT2-knockdown renal podocytes, septin4-K174 remains hyperacetylated and exacerbates hypertensive renal injury. By contrast, in Rosa26-Sirt2-Flag (SIRT2-TG) mice and SIRT2-knockdown renal podocytes reexpressing wild-type SIRT2, septin4-K174 is hypoacetylated and mitigates hypertensive renal injury.

CONCLUSIONS

Septin4, when activated through acetylation of K174 (K174Q), promotes hypertensive renal injury. Septin4-K174R, which mimics deacetylation by SIRT2, inhibits the cleaved-PARP1-cleaved-caspase3 pathway. Septin4-K174R acts as a renal protective factor, mitigating Ang II-induced hypertensive renal injury. These findings indicate that septin4-K174 is a potential therapeutic target for the treatment of hypertensive renal injury.

The Role of Praziquantel in the Prevention and Treatment of Fibrosis Associated with Schistosomiasis: A Review

Schistosomiasis remains a major global public health concern. Currently, the control of this neglected tropical disease still depends on chemotherapy to reduce the prevalence and intensity of the parasite infection. It has been widely accepted that praziquantel is highly effective against all species of Schistosoma, and this agent is virtually the only drug of choice for the treatment of human schistosomiasis. Mass drug administration (MDA) with praziquantel has been shown to be effective in greatly reducing the prevalence and morbidity due to schistosomiasis worldwide. In addition to antischistosomal activity, a large number of experiential and clinical evidence has demonstrated the action of praziquantel against fibrosis caused by S. mansoni and S. japonicum infections through decreasing the expression of fibrotic biomarkers such as α-smooth muscle actin (α-SMA), collagen, matrix metalloproteinase (MMP), and tissue inhibitor of metalloproteinase (TIMP), and inhibiting the expression of proinflammatory cytokines such as interleukin (IL)-6, tumor necrosis factor (TNF)-α, and transforming growth factor (TGF)-β, as well as chemokines, and similar antifibrotic activity was observed in mouse models of fibrosis induced by carbon tetrachloride (CCl4) and concanavalin A (Con-A). In this review, we discuss the role of praziquantel in the prevention and treatment of fibrosis associated with schistosomiasis and the possible mechanisms. We call for randomized, controlled clinical trials to evaluate the efficacy and safety of praziquantel in the treatment of schistosomiasis-induced hepatic fibrosis, and further studies to investigate the potential of praziquantel against fibrosis associated with alcohol consumption, viruses, and toxins seem justified.

The Differential and Dynamic Progression of Hepatic Inflammation and Immune Responses During Liver Fibrosis Induced by Schistosoma japonicum or Carbon Tetrachloride in Mice

Liver fibrosis can result from various causes and could progress to cirrhosis and cancer; however, there are no effective treatments due to that its molecular mechanism is unclear. liver fibrosis model made by Schistosoma japonicum (S. japonicum) infection or Carbon tetrachloride (CCl₄) intraperitoneal injection is a conventional model used in liver fibrosis-related studies for mechanism or pharmaceutical research purposes. But the differences in the pathological progression, immune responses and the underlying mechanism between the two liver fibrosis model have not been carefully compared and characterized, which hinders us from correctly understanding and making better use of the two models. In the present study, the pathological changes to the liver, and the cytokines, inflammatory factors, macrophages, and lymphocytes subsets involved were analyzed in the liver fibrosis model of S. japonicum infection or CCl₄ intraperitoneal injection. Additionally, the pathological progression, immune responses and the underlying injury mechanism in these two models were compared and characterized. The results showed that the changing trend of interleukin-13 (IL-13), transforming growth factor beta (TGF-β), inflammatory factors, and M1, M2 macrophages, were consistent with the development trend of fibrosis regardless of whether liver fibrosis was caused by S. japonicum or CCl₄. For lymphocyte subsets, the proportions of CD3⁺ T cells and CD4⁺ T cells decreased gradually, while proportion of CD8⁺ T cells peaked at 6 weeks in mice infected with S. japonicum and at 12 weeks in mice injected with CCl₄. With prolonged S. japonicum infection time, Th1 (CD4⁺IFN-γ⁺) immunity converted to Th2 (CD4⁺IL-4⁺)/Th17 (CD4⁺IL-17⁺) with weaker regulatory T cell (Treg) (CD4⁺CD25⁺FOXP3⁺) immunity. However, in liver fibrosis caused by CCl₄, Th1 cells occupied the dominant position, while proportions of Th2, Th17, and Treg cells decreased gradually. In conclusion, liver fibrosis was a complex pathological process that was regulated by a series of cytokines and immune cells. The pathological progressions and immune responses to S. japonicum or CCl₄ induced liver fibrosis were different, possibly because of their different injury mechanisms. The appropriate animal model should be selected according to the needs of different experiments and the pathogenic factors of liver fibrosis in the study.

Ziziphus spina-christi leaf extract ameliorates schistosomiasis liver granuloma, fibrosis, and oxidative stress through downregulation of fibrinogenic signaling in mice

Schistosomiasis is a widespread parasitic infection that affects humans, as well as wild and domestic animals. It ranks second after malaria, with a significant health and socio-economic impact in the developing countries. The objective of this study was to assess the anti-schistosomal impact of Ziziphus spina-christi leaf extract (ZLE) on Schistosoma mansoni-induced liver fibrosis in CD-1 Swiss male albino mice. S. mansoni infection was achieved by dipping of mouse tails in schistosomal cercariae. ZLE treatment was initiated at 46 days post-infection by administering a dose of the extract on a daily basis for 10 consecutive days. S. mansoni infection resulted in liver granuloma and fibrosis, with a drastic elevation in liver function factors, nitric oxide, and lipid peroxidation, which were associated with a reduction in glutathione content and substantial inhibition of antioxidant enzyme activities compared to those of the control. Induction of hepatic granuloma, oxidative stress, and fibrosis in the liver was controlled by ZLE administration, which also produced inhibition of matrix metalloproteinase-9, alpha-smooth muscle actin, transforming growth factor-β, and tissue inhibitors of metalloproteinases expressions. In addition, the S. mansoni-infected group exhibited an increase in Bax and caspase-3 levels and a decrease in Bcl-2 level. However, treatment with ZLE mainly mitigated apoptosis in the liver. Thus, the findings of this study revealed that Ziziphus spina-christi had anti-apoptotic, anti-fibrotic, antioxidant, and protective effects on S. mansoni-induced liver wounds. The benefits of Ziziphus spina-christi extract on S. mansoni were partly partially mediated by enhancing anti-fibrinogenic and nuclear factor erythroid 2–related factor 2 (Nrf2) pathways.

Sorafenib and praziquantel synergistically attenuate Schistosoma japonicum-induced liver fibrosis in mice

Liver fibrosis is an important process that occurs in most types of chronic liver diseases and often results in the end stage of liver diseases, such as cirrhosis, portal hypertension, and hepatocellular carcinoma. Sorafenib, a multiple tyrosine kinase inhibitor, has been shown to inhibit liver fibrosis in multiple experimental fibrosis mouse and rat models. The aim of this study was to test the therapeutic effect of sorafenib on liver fibrosis induced by infection with a parasite, Schistosoma japonicum, in mice. Mice were percutaneously infected through the abdomen with Schistosoma cercariae to develop a schistosomula liver fibrosis model. Eight weeks after infection, infected mice were treated with the anti-parasitic agent praziquantel for 2 days and sorafenib for 2 weeks. Hepatic histopathological changes were assessed using hematoxylin and eosin (HE) and Masson's trichome staining. The hepatic expression levels of collagen I, collagen III, alpha-smooth muscle actin (α-SMA), platelet-derived growth factor (PDGF), and PDGF receptor-beta (PDGFR-β) were analyzed by immunohistochemistry and western blot. Praziquantel administration alone but not sorafenib reduced liver fibrosis, and the combination of praziquantel and sorafenib significantly attenuated liver fibrosis in S. japonicum-infected mice. Moreover, sorafenib plus praziquantel markedly decreased the hepatic deposition of collagen and expression of fibrogenic genes in these mice. In conclusion, the use of sorafenib following praziquantel treatment may represent a potential therapeutic strategy for liver fibrosis induced by S. japonicum in patients.

Praziquantel Targets M1 Macrophages and Ameliorates Splenomegaly in Chronic Schistosomiasis

Splenomegaly is a common feature of many infectious diseases, including schistosomiasis japonica. However, the immunopathogenesis and the treatment of splenomegaly due to schistosomiasis have been largely neglected. Praziquantel (PZQ), a classical schistosomicide, has been demonstrated by us and others to have antifibrotic and anti-inflammatory activities against schistosomiasis. In this study, we investigated the effect of PZQ on alleviating the splenomegaly caused by Schistosoma japonicum infection in mice. The results showed that the number of macrophages, especially the number of M1 macrophages, was significantly increased in the enlarged spleens of infected mice (P < 0.001). After PZQ treatment for 4 weeks, the number of splenic macrophages, especially the number of M1 macrophages, was significantly reduced (P < 0.001) by the way of apoptosis, and another schistosomicide, mefloquine, had no effect either on the splenomegaly or on reducing the number of macrophages. Furthermore, by using the murine macrophage line RAW 264.7, we found that PZQ could inhibit the formation of the NLRP3 inflammasome and attenuate phagocytic activity in M1 macrophages. Thus, our studies suggest that PZQ plays a powerful role in ameliorating the splenomegaly caused by S. japonicum infection, which presents a new strategy for the therapy of splenomegaly resulting from other pathological conditions.

Soluble Egg Antigens of Schistosoma japonicum Induce Senescence of Activated Hepatic Stellate Cells by Activation of the FoxO3a/SKP2/P27 Pathway

BACKGROUND

Liver fibrosis was viewed as a reversible process. The activation of hepatic stellate cells (HSCs) is a key event in the process of liver fibrosis. The induction of senescence of HSCs would accelerate the clearance of the activated HSCs. Previously, we demonstrated that soluble egg antigens (SEA) of Schistosoma japonicum promoted the senescence of HSCs via STAT3/P53/P21 pathway. In this paper, our study was aimed to explore whether there are other signaling pathways in the process of SEA-induced HSCs aging and the underlying effect of SKP2/P27 signal on senescent HSCs.

METHODOLOGY/PRINCIPAL FINDINGS

Human hepatic stellate cell line, LX-2 cells, were cultured and stimulated with SEA. Western blot and cellular immunofluorescence analysis were performed to determine the expression of senescence-associated protein, such as P27, SKP2 and FoxO3a. Besides, RNA interfering was applied to knockdown the expression of related protein. The senescence of HSCs was determined by senescence-associated β-gal staining. We found that SEA increased the expression of P27 protein, whereas it inhibited the expression of SKP2 and FoxO3a. Knockdown of P27 as well as overexpression of SKP2 both suppressed the SEA-induced senescence of HSCs. In addition, the nuclear translocation of FoxO3a from the nucleus to the cytoplasm was induced by SEA stimulation.

CONCLUSIONS/SIGNIFICANCE

The present study demonstrates that SEA promotes HSCs senescence through the FoxO3a/SKP2/P27 pathway.

Soluble egg antigens of Schistosoma japonicum induce senescence in activated hepatic stellate cells by activation of the STAT3/p53/p21 pathway

Liver fibrosis is characterized by the activation of hepatic stellate cells (HSCs). Recent findings suggest that senescence of activated HSCs might limit the development of liver fibrosis. Based on previously observed anti-fibrotic effects of soluble egg antigens from Schistosoma japonicum in vitro, we hypothesized that SEA might play a crucial role in alleviating liver fibrosis through promoting senescence of activated HSCs. We show here that SEA inhibited expression of α-SMA and pro-collagen I and promoted senescence of activated HSCs in vitro. In addition, SEA induced an increased expression of P-p53 and p21. Knockdown of p53 inhibited the expression of p21 and failed to induce senescence of activated-HSCs. Phosphorylated STAT3 was elevated upon SEA stimulation, while loss of STAT3 decreased the level of p53 and senescence of HSCs. Results from immunoprecipitation analysis demonstrated that SOCS3 might be involved in the SEA-induced senescence in HSCs through its interaction with p53. This study demonstrates the potential capacity of SEA in restricting liver fibrosis through promoting senescence in HSCs. Furthermore, a novel STAT3-p53-p21 pathway might participate in the observed SEA-mediated senescence of HSCs. Our results suggest that SEA might carry potential therapeutic effects of restraining liver fibrosis through promoting senescence.

Clonorchis sinensis excretory/secretory products promote the secretion of TNF-alpha in the mouse intrahepatic biliary epithelial cells via Toll-like receptor 4

Background

Toll-like receptor 4 (TLR4), as one of the most important pathogen pattern recognitions (PPRs) plays a central role in elicitation of innate immunity and mediation of adaptive responses against foreign antigens. However, little is known of the roles of TLR4 in the immune responses of biliary epithelial cells (BECs) induced by Clonorchis sinensis, a parasite of significance in human health.

Methods

In the present study, the primary mouse intrahepatic biliary epithelial cells (MIBECs) were pre-treated with TLR4 inhibitor peptide or control peptide and then stimulated by excretory/secretory products (ESP) of C. sinensis, respectively. The expressions of TLR4 and relative cytokines were determined using western blot and a bead-based analytic detection system, respectively.

Results

The results showed that ESP of C. sinensis significantly increased the expression of TLR4 which promoted the expression of MyD88 and NF-κB in BECs; the levels of TNF-α but not IL-6 from MIBECs stimulated by ESP alone were also considerably increased, compared with the group of the medium stimulated. However, the concentration of TNF-α was significantly decreased when MIBECs were pre-treated with TLR4 inhibitor. In addition, ESP could depress the level of IL-6 in MIBECs which was elevated by LPS.

Conclusions

Our data for the first time demonstrate that ESP of C. sinensis can potently induce secretion of pro-inflammatory cytokines via TLR4 in MIBECs, which suggests that TLR4 plays an important role in host defenses against C. sinensis and the pathogenesis of clonorchiasis.