Study Objective and Hypothesis: The pathogenesis of fibrosis during metabolic dysfunction-associated steatohepatitis (MASH) is not fully understood. Our previous work indicate that the Eph/Ephrin signaling could be a major cell-cell signaling hub regulating fibrogenesis in MASH. While cell-cell interaction between HSC and liver sinusoidal endothelial cells (LSEC) has long been proposed as a driver for liver fibrosis, molecular mechanisms of their interaction have not been elaborated. In this study, we tested the hypothesis that EphrinB ligands expressed in LSEC plays a role in the pathogenesis of MASH fibrosis. Methods: Single nuclear RNA-sequencing of liver from human and mouse MASH were analyzed for Efnb1 and Efnb2 expression. Human liver tissues obtained from patients with MASH were assessed for pEphrinB expression. Plasma level of EphrinB2 was measured in MASH and healthy individuals. EphrinB1 deletion in LSEC were generated by crossing Efnb1 fl/fl mice with CDH5(PAC)-CreER T2 mice. Experimental MASH was developed in LSEC-specific Efnb1 knockout and wild type mice by feeding them with a choline-deficient amino-acid defined (CDAA) high fat diet for 8 weeks. Histology, flow cytometry, qPCR, biochemical assays and immunohistochemistry were used to dissect the contribution of LSEC- Efnb1 function in MASH. Statistical analysis was performed using ANOVA and Mann Whitney U test and a p-value < 0.05 was considered significant. Data: Single nuclear RNA sequencing showed that Efnb1 and Efnb2 are upregulated in LSEC of mice with MASH. Plasma level of Ephrin-B2 is significantly elevated in MASH patients compared to healthy individuals. Deletion of Efnb1 was achieved after tamoxifen administration, as depicted by reduced expression of Efnb1 mRNA level and EphrinB1 protein in the liver of LSEC Efnb1−/− mice compared to littermate ( Efnb1 fl/fl ) fed the CDAA-HFD. However, we noted an increased expression of Ephb receptors mRNA level in the liver of LSEC Efnb1−/− mice compared to littermate fed the CDAA-HFD. In addition, we noted an increased CDAA-HFD-mediated inflammation and fibrosis after deletion of Efnb1 in LSEC compared to littermates mice fed CDAA-HFD. Conclusions: Although EphrinB1 is upregulated in LSEC during advanced MASH, its deletion does not protect from MASH fibrosis. Given the functional redundancy between Ephrin-B ligands, deletion of one member of this family might not be suffcient to abolished EphB-EphrinB bidirectional signaling. NIDDK, NIAMS. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
The tumor microenvironment fuels tumorigenesis and induces the development of resistance to anticancer drugs. A growing number of reports support that the tumor microenvironment mediates these deleterious effects partly by overexpressing insulin-like growth factor 1 (IGF-1). IGF-1 is known for its role to support cancer progression and metastasis through the promotion of neovascularization in transforming tissues, and the promotion of the proliferation, maintenance and migration of malignant cells. Anti-IGF therapies showed potent anticancer effects and the ability to suppress cancer resistance to various chemotherapy drugs in in vivo and in vitro preclinical studies. However, high toxicity and resistance to these agents are increasingly being reported in clinical trials. We review data supporting the notion that tumor microenvironment mediates tumorigenesis partly through IGF-1 signaling pathway. We also discuss the therapeutic potential of IGF-1 receptor targeting, with special emphasis on the ability of IGF-R silencing to overcome chemotherapy drug resistance, as well as the challenges for clinical use of anti-IGF-1R therapies.
Erythropoietin producing hepatocellular (Eph)-Eph receptor interacting (Ephrin) receptor-ligand signaling has been implicated in the development of tissue fibrosis, though it has not been well defined in the kidney. We detected substantial up-regulation of expression and phosphorylation of the EphB2 receptor tyrosine kinase in fibrotic kidney tissue obtained both from mice subjected to the unilateral renal ischemia-reperfusion (IR) model at 14 days and in patients suffering from chronic kidney disease (CKD). Knockout (KO) mice lacking EphB2 expression exhibited a normal renal structure and function, indicating no major role for this receptor in kidney development or action. Although IR injury is well-known to cause tissue damage, fibrosis, and renal dysfunction, we found that kidneys from EphB2KO mice showed much less renal tubular injury and retained a more preserved renal function. IR-injured kidneys from EphB2 KOs exhibited greatly reduced fibrosis and inflammation compared with injured wildtype (WT) littermates, and this correlated with a significant reduction in renal expression of profibrotic molecules, inflammatory cytokines, NADPH oxidases, and markers for cell proliferation, tubular epithelial-to-mesenchymal transition (EMT), myofibroblast activation, and apoptosis. A panel of 760 fibrosis-associated genes were further assessed, revealing that 506 genes in WT mouse kidney following IR injury changed their expression. However, 70.9% of those genes were back to or close to normal in expression when EphB2 was deleted. These data indicate that endogenous EphB2 expression and signaling are abnormally activated after kidney injury and subsequently contribute to the development of renal fibrosis via regulation of multiple profibrotic pathways.
Genetic recombination during sexual reproduction within Plasmodium sp. contributes to parasite diversity and altered gene expression of certain surface markers. The pfs25 gene involved in the upset of gametocytogenesis is a candidate antigen in transmission blocking vaccine. This study investigated the polymorphism of Pfs25 within its 5’cis-control region in field isolates from different ecotypes in Cameroon. Symptomatic patients and asymptomatic healthy school children with a positive smear and from different ecozones were included. Parasite DNA was extracted and polymorphisms within pfs25, cg2-, msp-1, msp-2 and glurp genes were investigated by PCR-RFLP and DNA sequencing. Putative control elements of the 5’cis control regions of Pfs25 were identified by PCGENE software and enzymes were selected whose sequences produced or abolished restriction sites by mutations. Malaria infection was mainly caused by Plasmodium falciparum with sporadic occurrence of Plasmodium malariae and Plasmodium ovale. Analysis of the Pfs25 5’ cis-control region identified only one polymorphism (0.002%) that abolished an RsaI restriction site as part of the sequence TTTCTGTAC, located 40 bp downstream of the promoter and found at – 478 bp of the ATG. Analysis of the 5’ ciscontrol sequence of Pfs25 revealed minimal variation of the promoter region amid great zonal differences in parasite population. Altitudinal differences in parasite populations were not easily discernable.
Background & Aims: Emerging evidence suggests that the receptor tyrosine kinase EphB2 regulates tissue inflammation and fibrosis. However, its contribution to non-alcoholic fatty liver disease/non-alcoholic steatohepatitis (NAFLD or NASH) remains largely unknown; thus, we aimed to determine its role. Methods: In NAFLD/NASH patients, hepatic EphB2 and serum EphrinB2 ligands were evaluated. Disease phenotyping was performed in male and female wild type (WT), EphB2-/-, EphB2-kinase-dead (EphB2K661R), EphB2-kinase-overactive (EphB2F620D) mice, and in macrophage-specific EphB2-/- mice fed the obesogenic Gubra-Amylin NASH diet for 22-28 weeks and the Choline Deficient Amino-acid improved high-fat diets for 10-12 weeks. The role of EphB2 in inflammation was investigated in bone marrow-derived macrophages. Pharmacological inhibition of EphB2 for the treatment of NASH was also evaluated in vivo. Histology, hydroxyproline assay, flow cytometry, gene expression, biochemical assays, and RNA sequencing were used to dissect the molecular mechanism underlying macrophages’ EphB2 function in NASH. Results: Hepatic EphB2 was strongly upregulated in NASH patients and correlated with NASH fibrosis score. Serum EphrinB2 was also elevated in NASH patients. In mouse models of NASH, EphB2-/- mice showed a significant reduction in liver steatosis, inflammation, and fibrosis compared to WT mice. This is supported by a significant reduction of liver fat content, pro-inflammatory and fibrotic genes in EphB2-/- compared to WT mice. EphB2 forward signaling is likely the main driver of NASH progression as depicted by the significant increase in steatosis, inflammation, and fibrosis observed in EphB2F620D compared to WT and EphB2K661R mice. Flow cytometry revealed a reduced macrophage population in EphB2-/- mice compared to WT mice.In addition, bone marrow-derived macrophages from EphB2-/- mice showed reduced inflammation when stimulated with LPS in vitro. Interestingly, macrophage-specific EphB2-/- showed a reduction of NASH fibrosis and associated metabolic syndrome. Conclusions: We have identified EphB2 as a key player in the pathogenesis of fatty liver disease in humans and mice and its therapeutic targeting could potentially mitigate NASH fibrosis and associated metabolic syndrome National Institutes of Health (NIH) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
The efficacy of amodiaquine (AQ), sulphadoxine-pyrimethamine (SP) and the combination of SP+AQ in the treatment of Cameroonian children with clinical malaria was investigated. The prevalence of molecular markers for resistance to these drugs was studied to set the baseline for surveillance of their evolution with time. Seven hundred and sixty children aged 6-59 months with uncomplicated falciparum malaria were studied in three ecologically different regions of Cameroon - Mutengene (littoral equatorial forest), Yaoundé (forest-savannah mosaic) and Garoua (guinea-savannah). Study children were randomized to receive either AQ, SP or the combination AQ+SP. Clinical outcome was classified according to WHO criteria, as either early treatment failure (ETF), late clinical failure (LCF), late parasitological failure (LPF) or adequate clinical and parasitological response (ACPR). The occurrence of mutations in pfcrt, pfmdr1, dhfr and dhps genes was studied by either RFLP or dot blot techniques and the prevalence of these mutations related to parasitological and therapeutic failures. After correction for the occurrence of re-infection by PCR, ACPRs on day 28 for AQ, SP and AQ+SP were 71.2%, 70.1% and 80.9%, in Garoua, 79.2%, 62.5%, and 81.9% in Mutengene, and 80.3%, 67.5% and 76.2% in Yaoundé respectively. High levels of Pfcrt 76T (87.11%) and Pfmdr1 86Y mutations (73.83%) were associated with quinoline resistance in the south compared to the north, 31.67% (76T) and 22.08% (86Y). There was a significant variation (p < 0.001) of the prevalence of the SGK haplotype between Garoua in the north (8.33%), Yaoundé (36.29%) in the savannah-forest mosaic and Mutengene (66.41%) in the South of Cameroon and a weak relation between SGK haplotype and SP failure. The 540E mutation on the dhps gene was extremely rare (0.3%) and occurred only in Mutengene while the pfmdr1 1034K and 1040D mutations were not detected in any of the three sites. In this study the prevalence of molecular markers for quinoline and anti-folate resistances showed high levels and differed between the south and north of Cameroon. AQ, SP and AQ+SP treatments were well tolerated but with low levels of efficacy that suggested alternative treatments were needed in Cameroon since 2005.
The clinical manifestations of cerebral malaria (CM) are well correlated with underlying major pathophysiological events occurring during an acute malaria infection, the most important of which, is the adherence of parasitized erythrocytes to endothelial cells ultimately leading to sequestration and obstruction of brain capillaries. The consequent reduction in blood flow, leads to cerebral hypoxia, localized inflammation and release of neurotoxic molecules and inflammatory cytokines by the endothelium. The pharmacological regulation of these immunopathological processes by immunomodulatory molecules may potentially benefit the management of this severe complication. Adjunctive therapy of CM patients with an appropriate immunomodulatory compound possessing even moderate anti-malarial activity with the capacity to down regulate excess production of proinflammatory cytokines and expression of adhesion molecules, could potentially reverse cytoadherence, improve survival and prevent neurological sequelae. Current major drug discovery programmes are mainly focused on novel parasite targets and mechanisms of action. However, the discovery of compounds targeting the host remains a largely unexplored but attractive area of drug discovery research for the treatment of CM. This review discusses the properties of the plant immune-modifier curcumin and its potential as an adjunctive therapy for the management of this complication.
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