RESUMO
Environmental pollutants, including polychlorinated biphenyls (PCBs), act as endocrine disruptors and impair various physiological processes. PCB 126 is associated with steatohepatitis, fibrosis, cirrhosis, and other hepatic injuries. These disorders can be regulated by microRNAs (miRNAs). Therefore, this study aimed to investigate the role of miRNAs in non-alcoholic fatty liver disease associated with exposure to PCB 126. Adult male C57BL/6 mice were exposed to PCB 126 (5 µmol/kg of body weight) for 10 weeks. The PCB group showed lipid accumulation in the liver in the presence of macro- and microvesicular steatosis and fibrosis with increased inflammatory and profibrotic gene expression, consistent with non-alcoholic steatohepatitis (NASH). PCB exposure also upregulated miR-155 and miR-34a, which induce the expression of proinflammatory cytokines and inflammation in the liver and reduce the expression of peroxisome proliferator-activated receptor α, which, in turn, impairs lipid oxidation and hepatic steatosis. Therefore, the present study showed that PCB 126 induced NASH via potential mechanisms involving miR-155 and miR-34a, which may contribute to the development of new diagnostic markers and therapeutic strategies.
Assuntos
Cirrose Hepática , Camundongos Endogâmicos C57BL , MicroRNAs , Bifenilos Policlorados , Regulação para Cima , Animais , MicroRNAs/genética , MicroRNAs/metabolismo , Bifenilos Policlorados/toxicidade , Masculino , Camundongos , Cirrose Hepática/induzido quimicamente , Cirrose Hepática/genética , Cirrose Hepática/metabolismo , Cirrose Hepática/patologia , Regulação para Cima/efeitos dos fármacos , Fígado/metabolismo , Fígado/efeitos dos fármacos , Fígado/patologia , Hepatopatia Gordurosa não Alcoólica/induzido quimicamente , Hepatopatia Gordurosa não Alcoólica/metabolismo , Hepatopatia Gordurosa não Alcoólica/genética , Hepatopatia Gordurosa não Alcoólica/patologia , Poluentes Ambientais/toxicidade , Metabolismo dos Lipídeos/efeitos dos fármacos , Metabolismo dos Lipídeos/genéticaRESUMO
Phospholipases A2 (PLA2) comprise a superfamily of enzymes that specifically catalyze hydrolysis of the ester bond at the sn-2 position of glycerophospholipids, generating lysophospholipids and fatty acids. In Rhodnius prolixus, one of the main vectors of the Chagas's disease etiologic agent Trypanosoma cruzi, it was previously shown that lysophosphatidylcholine, a bioactive lipid, found in the insect's saliva, contributes to the inhibition of platelet aggregation, and increases the production of nitric oxide, an important vasodilator. Due to its role in potentially generating LPC, here we studied the PLA2 present in the salivary glands of R. prolixus. PLA2 activity is approximately 100 times greater in the epithelium than in the contents of salivary glands. Our study reveals the role of the RpPLA2XIIA gene in the insect feeding performance and in the fatty acids composition of phospholipids extracted from the salivary glands. Knockdown of RpPLA2XIIA significantly altered the relative amounts of palmitic, palmitoleic, oleic and linoleic acids. A short-term decrease in the expression of RpPLA2III and RpPLA2XIIA in the salivary glands of R. prolixus was evident on the third day after infection by T. cruzi. Taken together, our results contribute to the understanding of the role of PLA2 in the salivary glands of hematophagous insects and show that the parasite is capable of modulating even tissues that are not colonized by it.
Assuntos
Fosfolipases A2 , Rhodnius , Glândulas Salivares , Trypanosoma cruzi , Animais , Rhodnius/parasitologia , Rhodnius/enzimologia , Rhodnius/genética , Glândulas Salivares/parasitologia , Glândulas Salivares/enzimologia , Glândulas Salivares/metabolismo , Trypanosoma cruzi/genética , Trypanosoma cruzi/enzimologia , Fosfolipases A2/metabolismo , Fosfolipases A2/genética , Ácidos Graxos/metabolismo , Doença de Chagas/parasitologia , Insetos Vetores/parasitologia , Insetos Vetores/enzimologiaRESUMO
Chagas disease, endemic from Latin America, is caused by Trypanosoma cruzi and is transmitted by triatomine feces. This parasite undergoes complex morphological changes through its life cycle, promoted by significant changes in signal transduction pathways. The activity of protein kinase CK2 has been described in trypanosomatids. Using a specific peptide and radioactive ATP, we identified CK2 activity on the cellular surface and the cytoplasmic content in Trypanosoma cruzi, apart from the secreted form. Dephosphorylated casein promoted an increase of 48% in the secreted CK2 activity. Total extract of peritoneal macrophages from BALB/c and inactivated human serum promoted an increase of 67% and 36%, respectively, in this activity. The protein secreted by parasites was purified by HPLC and had shown compatibility with the catalytic subunit of mammalian CK2. Incubation of the parasites with CK2 inhibitors, added to the culture medium, prevented their growth. The opposite was observed when CK2 activators were used. Results of interaction between Trypanosoma cruzi and the gut of the vector have revealed that, in the presence of CK2 inhibitors, there is a reduction in the association rate. A similar inhibition profile was seen in the Trypanosoma cruzi-macrophages interaction, confirming the importance of this enzyme in the life cycle of this protozoan.
Assuntos
Doença de Chagas , Trypanosoma cruzi , Animais , Humanos , Trypanosoma cruzi/metabolismo , Caseína Quinase II/metabolismo , Doença de Chagas/parasitologia , Invertebrados , MamíferosRESUMO
Leprosy is a chronic infectious disease caused by the intracellular bacillus Mycobacterium leprae (M. leprae), which is known to infect skin macrophages and Schwann cells. Although adipose tissue is a recognized site of Mycobacterium tuberculosis infection, its role in the histopathology of leprosy was, until now, unknown. We analyzed the M. leprae capacity to infect and persist inside adipocytes, characterizing the induction of a lipolytic phenotype in adipocytes, as well as the effect of these infected cells on macrophage recruitment. We evaluated 3T3-L1-derived adipocytes, inguinal adipose tissue of SWR/J mice, and subcutaneous adipose tissue biopsies of leprosy patients. M. leprae was able to infect 3T3-L1-derived adipocytes in vitro, presenting a strong lipolytic profile after infection, followed by significant cholesterol efflux. This lipolytic phenotype was replicated in vivo by M. leprae injection into mice inguinal adipose tissue. Furthermore, M. leprae was detected inside crown-like structures in the subcutaneous adipose tissue of multibacillary patients. These data indicate that subcutaneous adipose tissue could be an important site of infection, and probably persistence, for M. leprae, being involved in the modulation of the innate immune control in leprosy via the release of cholesterol, MCP-1, and adiponectin.
Assuntos
Hanseníase , Mycobacterium leprae , Camundongos , Animais , Humanos , Mycobacterium leprae/fisiologia , Lipólise , Adipócitos/patologia , Imunidade , ColesterolRESUMO
Leprosy is a chronic infectious disease caused by the intracellular bacillus Mycobacterium leprae (M. leprae), which is known to infect skin macrophages and Schwann cells. Although adipose tissue is a recognized site of Mycobacterium tuberculosis infection, its role in the histopathology of leprosy was, until now, unknown. We analyzed the M. leprae capacity to infect and persist inside adipocytes, characterizing the induction of a lipolytic phenotype in adipocytes, as well as the effect of these infected cells on macrophage recruitment. We evaluated 3T3-L1-derived adipocytes, inguinal adipose tissue of SWR/J mice, and subcutaneous adipose tissue biopsies of leprosy patients. M. leprae was able to infect 3T3-L1-derived adipocytes in vitro, presenting a strong lipolytic profile after infection, followed by significant cholesterol efflux. This lipolytic phenotype was replicated in vivo by M. leprae injection into mice inguinal adipose tissue. Furthermore, M. leprae was detected inside crown-like structures in the subcutaneous adipose tissue of multibacillary patients. These data indicate that subcutaneous adipose tissue could be an important site of infection, and probably persistence, for M. leprae, being involved in the modulation of the innate immune control in leprosy via the release of cholesterol, MCP-1, and adiponectin.
Assuntos
Humanos , Animais , Ratos , Mycobacterium leprae/fisiologia , Adipócitos/patologia , LipóliseRESUMO
Brown marine macroalga Padina gymnospora (Phaeophyceae, Ochrophyta) produces both secondary metabolites (phlorotannins) and precipitate calcium carbonate (CaCO3-aragonite) on its surface as potential defensive strategies against herbivory. Here, we have evaluated the effect of natural concentrations of organic extracts (dichloromethane-DI; ethyl acetate-EA and methanol-ME, and three isolated fractions) and mineralized tissues of P. gymnospora as chemical and physical resistance, respectively, against the sea urchin Lytechinus variegatus through experimental laboratory feeding bioassays. Fatty acids (FA), glycolipids (GLY), phlorotannins (PH) and hydrocarbons (HC) were also characterized and/or quantified in extracts and fractions from P. gymnospora using nuclear magnetic resonance (NMR) and gas chromatography (GC) coupled to mass spectrometry (CG/MS) or GC coupled to flame ionization detector (FID) and chemical analysis. Our results showed that chemicals from the EA extract of P. gymnospora were significantly important in reducing consumption by L. variegatus, but the CaCO3 did not act as a physical protection against consumption by this sea urchin. An enriched fraction containing 76% of the new hydrocarbon 5Z,8Z,11Z,14Z-heneicosatetraene exhibited a significant defensive property, while other chemicals found in minor amounts, such as GLY, PH, saturated and monounsaturated FAs and CaCO3 did not interfere with the susceptibility of P. gymnospora to L. variegatus consumption. We suggest that the unsaturation of the 5Z,8Z,11Z,14Z-heneicosatetraene from P. gymnospora is probably an important structural characteristic responsible for the defensive property verified against the sea urchin.
RESUMO
Leprosy is a chronic infectious disease caused by Mycobacterium leprae infection in Schwann cells. Axonopathy is considered a hallmark of leprosy neuropathy and is associated with the irreversible motor and sensory loss seen in infected patients. Although M. leprae is recognized to provoke Schwann cell dedifferentiation, the mechanisms involved in the contribution of this phenomenon to neural damage remain unclear. In the present work, we used live M. leprae to infect the immortalized human Schwann cell line ST8814. The neurotoxicity of infected Schwann cell-conditioned medium (SCCM) was then evaluated in a human neuroblastoma cell lineage and mouse neurons. ST8814 Schwann cells exposed to M. leprae affected neuronal viability by deviating glial 14 C-labeled lactate, important fuel of neuronal central metabolism, to de novo lipid synthesis. The phenolic glycolipid-1 (PGL-1) is a specific M. leprae cell wall antigen proposed to mediate bacterial-Schwann cell interaction. Therefore, we assessed the role of the PGL-1 on Schwann cell phenotype by using transgenic M. bovis (BCG)-expressing the M. leprae PGL-1. We observed that BCG-PGL-1 was able to induce a phenotype similar to M. leprae, unlike the wild-type BCG strain. We next demonstrated that this Schwann cell neurotoxic phenotype, induced by M. leprae PGL-1, occurs through the protein kinase B (Akt) pathway. Interestingly, the pharmacological inhibition of Akt by triciribine significantly reduced free fatty acid content in the SCCM from M. leprae- and BCG-PGL-1-infected Schwann cells and, hence, preventing neuronal death. Overall, these findings provide novel evidence that both M. leprae and PGL-1, induce a toxic Schwann cell phenotype, by modifying the host lipid metabolism, resulting in profound implications for neuronal loss. We consider this metabolic rewiring a new molecular mechanism to be the basis of leprosy neuropathy.
Assuntos
Hanseníase , Mycobacterium leprae , Humanos , Animais , Camundongos , Mycobacterium leprae/genética , Mycobacterium leprae/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Glicolipídeos/metabolismo , Vacina BCG/metabolismo , Hanseníase/microbiologia , Células de Schwann/metabolismoRESUMO
AIMS: Endoplasmic reticulum (ER) stress poses a new pathological mechanism for metabolic-associated fatty liver disease (MAFLD). MAFLD treatment has encompassed renin-angiotensin system (RAS) blockers and aerobic exercise training, but their association with hepatic ER stress is not well known. Therefore, we aimed to compare the effects of hepatic RAS modulation by enalapril and/or aerobic exercise training over ER stress in MAFLD caused by a diet-induced obesity model. MAIN METHODS: C57BL/6 mice were fed a standard-chow (CON, n = 10) or a high-fat (HF, n = 40) diet for 8 weeks. HF group was then randomly divided into: HF (n = 10), HF + Enalapril (EN, n = 10), HF + Aerobic exercise training (AET, n = 10), and HF + Enalapril+Aerobic exercise training (EN + AET, n = 10) for 8 more weeks. Body mass (BM) and glucose profile were evaluated. In the liver, ACE and ACE2 activity, morphology, lipid profile, and protein expression of ER stress and metabolic markers were assessed. KEY FINDINGS: Both enalapril and aerobic exercise training provided comparable efficacy in improving diet-induced MAFLD through modulation of RAS and ER stress, but the latter was more efficient in improving ER stress, liver damage and metabolism. SIGNIFICANCE: This is the first study to evaluate pharmacological (enalapril) and non-pharmacological (aerobic exercise training) RAS modulators associated with ER stress in a diet-induced MAFLD model.
Assuntos
Enalapril , Estresse do Retículo Endoplasmático , Animais , Camundongos , Biomarcadores/metabolismo , Dieta , Enalapril/farmacologia , Camundongos Endogâmicos C57BLRESUMO
The liver is an essential regulator of energy metabolism, and its function can be disrupted by nutritional alterations. Since liver development continues during breastfeeding nutritional challenges during this period predispose patients to diseases throughout life. A maternal protein-restricted (PR) diet during lactation promotes reductions in the body weight, adiposity, and plasma glucose and insulin, leptin resistance and an increase in corticosterone and catecholamines in adult male rat offspring. Here, we investigated hepatic metabolism in the offspring (both sexes) of PR (8% protein diet during lactation) and control (23% protein diet) dams. Both male and female offspring were evaluated at 6 months of age. PR males had no liver steatosis and manifested a reduction in lipids in hepatocytes adjacent to the vasculature. These animals had lower levels of esterified cholesterol in hepatocytes, suggesting higher biliary excretion, unchanged glycolysis and gluconeogenesis, and lower contents of the markers of mitochondrial redox balance and endoplasmic reticulum (ER) stress response and estrogen receptor alpha. PR females showed normal hepatic morphology associated with higher uptake of cholesterol esters, normal glycolysis and gluconeogenesis, and lower ER stress parameters without changes in the key markers of the redox balance. Additionally, these animals had lower content of estrogen receptor alpha and higher content of androgen receptor. The maternal PR diet during lactation did not program hepatic lipid accumulation in the adult progeny. However, several repair homeostasis pathways were altered in males and females, possibly compromising maintenance of normal liver function.
Assuntos
Dieta com Restrição de Proteínas , Efeitos Tardios da Exposição Pré-Natal , Adiposidade , Animais , Receptor alfa de Estrogênio , Feminino , Lactação , Masculino , Fenômenos Fisiológicos da Nutrição Materna , Gravidez , Ratos , Ratos WistarRESUMO
A significant percentage of exogenous cholesterol was found in promastigotes and amastigotes of all studied species of Leishmania, suggesting a biological role for this molecule. Previous studies have shown that promastigotes of Leishmania uptake more low-density lipoprotein (LDL) particles under pharmacological pressure and are more susceptible to ergosterol inhibition in the absence of exogenous sources of cholesterol. This work shows that the host's LDL is available to intracellular amastigotes and that the absence of exogenous cholesterol enhances the potency of sterol biosynthesis inhibitors in infected macrophages. A complete understanding of cholesterol transport to the parasitophorous vacuole can guide the development of a new drug class to be used in combination with sterol biosynthesis inhibitors for the treatment of leishmaniases.