Kinin B1 Receptor Antagonism Prevents Acute Kidney Injury to Chronic Kidney Disease Transition in Renal Ischemia-Reperfusion by Increasing the M2 Macrophages Population in C57BL6J Mice.

BACKGROUND: Chronic kidney disease (CKD) is a multifactorial, world public health problem that often develops as a consequence of acute kidney injury (AKI) and inflammation. Strategies are constantly sought to avoid and mitigate the irreversibility of this disease. One of these strategies is to decrease the inflammation features of AKI and, consequently, the transition to CKD. METHODS: C57Bl6J mice were anesthetized, and surgery was performed to induce unilateral ischemia/reperfusion as a model of AKI to CKD transition. For acute studies, the animals received the Kinin B1 receptor (B1R) antagonist before the surgery, and for the chronic model, the animals received one additional dose after the surgery. In addition, B1R genetically deficient mice were also challenged with ischemia/reperfusion. RESULTS: The absence and antagonism of B1R improved the kidney function following AKI and prevented CKD transition, as evidenced by the preserved renal function and prevention of fibrosis. The protective effect of B1R antagonism or deficiency was associated with increased levels of macrophage type 2 markers in the kidney. CONCLUSIONS: The B1R is pivotal to the evolution of AKI to CKD, and its antagonism shows potential as a therapeutic tool in the prevention of CKD following AKI.

Kinin B1 receptor deficiency protects mice fed by cafeteria diet from abnormal glucose homeostasis.

The kallikrein-kinin system has been implicated in body weight and glucose homeostasis. Their major effectors act by binding to the kinin B2 and B1 receptors. It was assessed the role of the kinin B1 receptor in weight and glucose homeostasis in B1 receptor knockout mice (B1RKO) subjected to a cafeteria diet (CAF). Wild-type (WT) and B1RKO male mice (C57BL/6 background; 8 weeks old) were fed a standard diet (SD) or CAF for 14 weeks, ad libitum, and four groups were formed: WT-SD; B1RKO-SD; WT-CAF; B1RKO-CAF. Body weight and food intake were assessed weekly. It was performed glucose tolerance (GTT) and insulin tolerance tests (ITT), and HOMA-IR, HOMA-ß and HOMA-ß* 1/HOMA-IR were calculated. Islets from WT and B1RKO were isolated in order to measure the insulin secretion. Western blot was used to assess the hepatic AKT phosphorylation and qPCR to assess gene expression. CAF induced a higher body mass gain in B1RKO compared to WT mice. CAF diet increased epididymal fat depot mass, hepatic fat infiltration and hepatic AKT phosphorylation in both genotypes. However, B1RKO mice presented lower glycemic response during GTT when fed with CAF, and a lower glucose decrease in the ITT. This higher resistance was overcomed with higher insulin secretion when stimulated by high glucose, resulting in higher glucose uptake in the GTT when submitted to CAF, despite lower insulin sensitivity. Islets from B1RKO delivered 4 times more insulin in 3-month-old mice than islets from WT. The higher insulin disposition index and high insulin delivery of B1RKO can explain the decreased glucose excursion during GTT. In conclusion, CAF increased the ß-cell function in B1RKO mice, compensated by the diet-induced insulin resistance and resulting in a healthier glycemic response despite the higher weight gain.

PLP2-derived peptide Rb4 triggers PARP-1-mediated necrotic death in murine melanoma cells.

Malignant melanoma is the main cause of death in patients with skin cancer. Overexpression of Proteolipid protein 2 (PLP2) increased tumor metastasis and the knockdown of PLP2 inhibited the growth and metastasis of melanoma cells. In the present work, we studied the antitumor activity of peptide Rb4 derived from protein PLP2. In vitro, Rb4 induced F-actin polymerization, prevented F-actin depolymerization and increased the ER-derived cytosolic calcium. Such effects were associated with necrosis of murine melanoma B16F10-Nex2 cells and with inhibition of the viability of human cancer cell lines. Loss of plasma membrane integrity, dilation of mitochondria, cytoplasm vacuolation and absence of chromatin condensation characterized tumor cell necrosis. Cleavage of PARP-1 and inhibition of RIP1 expression were also observed. In vivo, peptide Rb4 reduced the lung metastasis of tumor cells and delayed the subcutaneous melanoma growth in a syngeneic model. Rb4 induced the expression of two DAMPs molecules, HMGB1 and calreticulin, in B16F10-Nex2. Our results suggest that peptide Rb4 acts directly on tumor cells inducing the expression of DAMPs, which trigger the immunoprotective effect in vivo against melanoma cells. We suggest that peptide Rb4 is a promising compound to be developed as an anticancer drug.

Overexpression of Plasmodium falciparum M1 Aminopeptidase Promotes an Increase in Intracellular Proteolysis and Modifies the Asexual Erythrocytic Cycle Development.

Plasmodium falciparum, the most virulent of the human malaria parasite, is responsible for high mortality rates worldwide. We studied the M1 alanyl-aminopeptidase of this protozoan (PfA-M1), which is involved in the final stages of hemoglobin cleavage, an essential process for parasite survival. Aiming to help in the rational development of drugs against this target, we developed a new strain of P. falciparum overexpressing PfA-M1 without the signal peptide (overPfA-M1). The overPfA-M1 parasites showed a 2.5-fold increase in proteolytic activity toward the fluorogenic substrate alanyl-7-amido-4-methylcoumarin, in relation to the wild-type group. Inhibition studies showed that overPfA-M1 presented a lower sensitivity against the metalloaminopeptidase inhibitor bestatin and to other recombinant PfA-M1 inhibitors, in comparison with the wild-type strain, indicating that PfA-M1 is a target for the in vitro antimalarial activity of these compounds. Moreover, overPfA-M1 parasites present a decreased in vitro growth, showing a reduced number of merozoites per schizont, and also a decrease in the iRBC area occupied by the parasite in trophozoite and schizont forms when compared to the controls. Interestingly, the transgenic parasite displays an increase in the aminopeptidase activity toward Met-, Ala-, Leu- and Arg-7-amido-4-methylcoumarin. We also investigated the potential role of calmodulin and cysteine proteases in PfA-M1 activity. Taken together, our data show that the overexpression of PfA-M1 in the parasite cytosol can be a suitable tool for the screening of antimalarials in specific high-throughput assays and may be used for the identification of intracellular molecular partners that modulate their activity in P. falciparum.

PPAR-α Deletion Attenuates Cisplatin Nephrotoxicity by Modulating Renal Organic Transporters MATE-1 and OCT-2.

Cisplatin is a chemotherapy drug widely used in the treatment of solid tumors. However, nephrotoxicity has been reported in about one-third of patients undergoing cisplatin therapy. Proximal tubules are the main target of cisplatin toxicity and cellular uptake; elimination of this drug can modulate renal damage. Organic transporters play an important role in the transport of cisplatin into the kidney and organic cations transporter 2 (OCT-2) has been shown to be one of the most important transporters to play this role. On the other hand, multidrug and toxin extrusion 1 (MATE-1) transporter is the main protein that mediates the extrusion of cisplatin into the urine. Cisplatin nephrotoxicity has been shown to be enhanced by increased OCT-2 and/or reduced MATE-1 activity. Peroxisome proliferator-activated receptor alpha (PPAR-α) is the transcription factor which controls lipid metabolism and glucose homeostasis; it is highly expressed in the kidneys and interacts with both MATE-1 and OCT-2. Considering the above, we treated wild-type and PPAR-α knockout mice with cisplatin in order to evaluate the severity of nephrotoxicity. Cisplatin induced renal dysfunction, renal inflammation, apoptosis and tubular injury in wild-type mice, whereas PPAR-α deletion protected against these alterations. Moreover, we observed that cisplatin induced down-regulation of organic transporters MATE-1 and OCT-2 and that PPAR-α deletion restored the expression of these transporters. In addition, PPAR-α knockout mice at basal state showed increased MATE-1 expression and reduced OCT-2 levels. Here, we show for the first time that PPAR-α deletion protects against cisplatin nephrotoxicity and that this protection is via modulation of the organic transporters MATE-1 and OCT-2.

Gemfibrozil Induces Anemia, Leukopenia and Reduces Hematopoietic Stem Cells via PPAR-α in Mice.

Hypercholesterolemia, also called high cholesterol, is a form of hyperlipidemia, which may be a consequence of diet, obesity or diabetes. In addition, increased levels of low-density lipoprotein (LDL) and reduced levels of high-density lipoprotein (HDL) cholesterol are associated with a higher risk of atherosclerosis and coronary heart disease. Thus, controlling cholesterol levels is commonly necessary, and fibrates have been used as lipid-lowering drugs. Gemfibrozil is a fibrate that acts via peroxisome proliferator-activated receptor alpha to promote changes in lipid metabolism and decrease serum triglyceride levels. However, anemia and leukopenia are known side effects of gemfibrozil. Considering that gemfibrozil may lead to anemia and that gemfibrozil acts via peroxisome proliferator-activated receptor alpha, we treated wild-type and peroxisome proliferator-activated receptor alpha-knockout mice with gemfibrozil for four consecutive days. Gemfibrozil treatment led to anemia seven days after the first administration of the drug; we found reduced levels of hemoglobin, as well as red blood cells, white blood cells and a reduced percentage of hematocrits. PPAR-alpha-knockout mice were capable of reversing all of those reduced parameters induced by gemfibrozil treatment. Erythropoietin levels were increased in the serum of gemfibrozil-treated animals, and we also observed an increased expression of hypoxia-inducible factor-2 alpha (HIF-2α) and erythropoietin in renal tissue, while PPAR-alpha knockout mice treated with gemfibrozil did not present increased levels of serum erythropoietin or tissue HIF-2α and erythropoietin mRNA levels in the kidneys. We analyzed bone marrow and found that gemfibrozil reduced erythrocytes and hematopoietic stem cells in wild-type mice but not in PPAR-alpha-knockout mice, while increased colony-forming units were observed only in wild-type mice treated with gemfibrozil. Here, we show for the first time that gemfibrozil treatment leads to anemia and leukopenia via peroxisome proliferator-activated receptor alpha in mice.

Evaluación de la proteólisis en células aisladas vivas de Plasmodium falciparum aisladas durante los estadios asexuales sanguíneos / Proteolysis assessment in isolated Plasmodium falciparum living cells at the asexual blood stages

It has been demonstrated that proteases play crucial roles in Plasmodium falciparum infection and therefore have been considered as targets for the development of new therapeutic drugs. The aim of this study was to describe the specific proteolytic activity profile in all blood stages of P. falciparum isolated parasites in order to explore new antimalarial options. For this purpose, we used the fluorogenic substrate Z-Phe-Arg-MCA (Z: carbobenzoxy, MCA: 7-amino-4-methyl coumarine) and classic inhibitors for the different classes of proteolytic enzymes, such as phenylmethylsulfonyl fluoride (PMSF), 1.10-phenantroline, pepstatin A and E64 to study the inhibition profiles. As expected, due to the high metabolic activity in mature stages, the substrate was mostly degraded in the trophozoite and schizont, with specific activities ~ 20 times higher than in early stages (merozoite/rings). The major actors in substrate hydrolysis were cysteine proteases, as confirmed by the complete hydrolysis inhibition with E64 addition. Proteolytic activity was also inhibited in the presence of PMSF in all but the schizont stage. However, PMSF inhibition was the result of unspecific interaction with cysteine proteases as demonstrated by reversion of inhibition by dithiotreitol (DTT), indicating that serine protease activity is very low or null. To our knowledge, this is the first report aiming to describe the proteolytic profile of P. falciparum isolated parasites at all the erythrocytic cycle stages. The results and protocol described herein can be useful in the elucidation of stage specific action of proteolysis-inhibiting drugs and aid in the development of antimalarial compounds with protease inhibitory activity(AU)

e ha demostrado que las proteasas desempeñan funciones vitales en la infección por Plasmodium falciparum, y por lo tanto se consideran dianas en la elaboración de nuevos medicamentos terapéuticos. El objetivo del estudio era describir el perfil de actividad proteolítica específica de todas las etapas sanguíneas de parásitos aislados de P. falciparum con vistas a explorar nuevas opciones antimaláricas. Con ese propósito, utilizamos el sustrato fluorogénico Z-Phe-Arg-AMC (Z: carbobenzoxi, AMC: 7-amino-4-metilcumarina) e inhibidores clásicos para las diferentes clases de enzimas proteolíticas, tales como el fluoruro de fenilmetilsulfonilo (PMSF), 1,10-fenantrolina, pepstatina A y E64 para estudiar los perfiles de inhibición. Como se esperaba, debido a la elevada actividad metabólica de las etapas de madurez, el sustrato fue degradado mayormente en el trofozoíto y el esquizonte, con actividad específica ~ 20 veces superior a la de las etapas tempranas (merozoíto/ anillos). Los principales actores en la hidrólisis del sustrato fueron las cisteínas proteasas, lo que fue confirmado por la inhibición completa de la hidrólisis con la adición de E64. La actividad proteolítica también fue inhibida en presencia de PMSF en todas las etapas excepto el esquizonte. Sin embargo, la inhibición del PMSF fue resultado de una interacción inespecífica con las cisteínas proteasas, según lo demuestra la reversión de la inhibición con el ditiotreitol (DTT), lo que indica que la actividad de la serina proteasa es muy baja o inexistente. Que sepamos, este es el primer informe dirigido a describir el perfil proteolítico de parásitos aislados de P. falciparum en todas las etapas del ciclo eritrocítico. Los resultados y el protocolo que aquí se describen pueden ser útiles para dilucidar la acción específica de los medicamentos inhibidores de proteólisis en cada etapa, así como contribuir al desarrollo de compuestos antimaláricos con actividad inhibidora de la proteasa(AU)

Improvement of antimalarial activity of a 3-alkylpiridine alkaloid analog by replacing the pyridine ring to a thiazole-containing heterocycle: Mode of action, mutagenicity profile, and Caco-2 cell-based permeability.

The development of new antimalarial drugs is urgent to overcome the spread of resistance to the current treatment. Herein we synthesized the compound 3, a hit-to­lead optimization of a thiazole based on the most promising 3-alkylpyridine marine alkaloid analog. Compound 3 was tested against Plasmodium falciparum and has shown to be more potent than its precursor (IC50 values of 1.55 and 14.7 µM, respectively), with higher selectivity index (74.7) for noncancerous human cell line. This compound was not mutagenic and showed genotoxicity only at concentrations four-fold higher than its IC50. Compound 3 was tested in vivo against Plasmodium berghei NK65 strain and inhibited the development of parasite at 50 mg/kg. In silico and UV-vis approaches determined that compound 3 acts impairing hemozoin crystallization and confocal microscopy experiments corroborate these findings as the compound was capable of diminishing food vacuole acidity. The assay of uptake using human intestinal Caco-2 cell line showed that compound 3 is absorbed similarly to chloroquine, a standard antimalarial agent. Therefore, we present here compound 3 as a potent new lead antimalarial compound.

Nephropathy in Hypertensive Animals Is Linked to M2 Macrophages and Increased Expression of the YM1/Chi3l3 Protein.

Macrophages contribute to a continuous increase in blood pressure and kidney damage in hypertension, but their polarization status and the underlying mechanisms have not been clarified. This study revealed an important role for M2 macrophages and the YM1/Chi3l3 protein in hypertensive nephropathy in a mouse model of hypertension. Bone marrow cells were isolated from the femurs and tibia of male FVB/N (control) and transgenic hypertensive animals that overexpressed the rat form of angiotensinogen (TGM(rAOGEN)123, TGM123-FVB/N). The cells were treated with murine M-CSF and subsequently with LPS+IFN-γ to promote their polarization into M1 macrophages and IL-4+IL-13 to trigger the M2 phenotype. We examined the kidneys of TGM123-FVB/N animals to assess macrophage polarization and end-organ damage. mRNA expression was evaluated using real-time PCR, and protein levels were assessed through ELISA, CBA, Western blot, and immunofluorescence. Histology confirmed high levels of renal collagen. Cells stimulated with LPS+IFN-γ in vitro showed no significant difference in the expression of CD86, an M1 marker, compared to cells from the controls or the hypertensive mice. When stimulated with IL-4+IL-13, however, macrophages of the hypertensive group showed a significant increase in CD206 expression, an M2 marker. The M2/M1 ratio reached 288%. Our results indicate that when stimulated in vitro, macrophages from hypertensive mice are predisposed toward polarization to an M2 phenotype. These data support results from the kidneys where we found an increased infiltration of macrophages predominantly polarized to M2 associated with high levels of YM1/Chi3l3 (91,89%), suggesting that YM1/Chi3l3 may be a biomarker of hypertensive nephropathy.

Inhibition of Plasmodium falciparum cysteine proteases by the sugarcane cystatin CaneCPI-4.

Malaria is a disease caused by Plasmodium parasites that affects hundreds of millions of people. Plasmodium proteases are involved in invasion, erythrocyte egress and degradation of host proteins. Falcipains are well-studied cysteine peptidases located in P. falciparum food vacuoles that participate in hemoglobin degradation. Cystatins are natural cysteine protease inhibitors that are implicated in a wide range of regulatory processes. Here, we report that a cystatin from sugarcane, CaneCPI-4, is selectively internalized into P. falciparum infected erythrocytes and is not processed by the parasite proteolytic machinery. Furthermore, we demonstrated the inhibition of P. falciparum cysteine proteases by CaneCPI-4, suggesting that it can exert inhibitory functions inside the parasites. The inhibition of the proteolytic activity of parasite cells is specific to this cystatin, as the addition of an anti-CaneCPI-4 antibody completely abolished the inhibition. We extended the studies to recombinant falcipain-2 and falcipain-3 and demonstrated that CaneCPI-4 strongly inhibits these enzymes, with IC50 values of 12nM and 42nM, respectively. We also demonstrated that CaneCPI-4 decreased the hemozoin formation in the parasites, affecting the parasitemia. Taken together, this study identified a natural molecule as a potential antimalarial that specifically targets falcipains and also contributes to a better understanding of macromolecule acquisition by Plasmodium falciparum infected RBCs.

PVALB diminishes [Ca2+] and alters mitochondrial features in follicular thyroid carcinoma cells through AKT/GSK3ß pathway.

We have identified previously a panel of markers (C1orf24, ITM1 and PVALB) that can help to discriminate benign from malignant thyroid lesions. C1orf24 and ITM1 are specifically helpful for detecting a wide range of thyroid carcinomas, and PVALB is particularly valuable for detecting the benign Hürthle cell adenoma. Although these markers may ultimately help patient care, the current understanding of their biological functions remains largely unknown. In this article, we investigated whether PVALB is critical for the acquisition of Hürthle cell features and explored the molecular mechanism underlying the phenotypic changes. Through ectopic expression of PVALB in thyroid carcinoma cell lines (FTC-133 and WRO), we demonstrated that PVALB sequesters free cytoplasmic Ca(2+), which ultimately lowers calcium levels and precludes endoplasmic reticulum (ER) Ca(2+) refilling. These results were accompanied by induced expression of PERK, an ER stress marker. Additionally, forced expression of PVALB reduces Ca(2+) inflow in the mitochondria, which can in turn cause changes in mitochondria morphology, increase mitochondria number and alter subcellular localization. These findings share striking similarity to those observed in Hürthle cell tumors. Moreover, PVALB inhibits cell growth and induces cell death, most likely through the AKT/GSK-3ß. Finally, PVALB expression coincides with Ca(2+) deposits in HCA tissues. Our data support the hypothesis that the loss of PVALB plays a role in the pathogenesis of thyroid tumors.

Specific calpain activity evaluation in Plasmodium parasites.

In the intraerythrocytic trophozoite stages of Plasmodium falciparum, the calcium-dependent cysteine protease calpain (Pf-calpain) has an important role in the parasite calcium modulation and cell development. We established specific conditions to follow by confocal microscopy and spectrofluorimetry measurements the intracellular activity of Pf-calpain in live cells. The catalytic activity was measured using the fluorogenic Z-Phe-Arg-MCA (where Z is carbobenzoxy and MCA is 4-methylcoumaryl-7-amide). The calmodulin inhibitor calmidazolium and the sarcoplasmic reticulum calcium ATPase inhibitor thapsigargin were used for modifications in the cytosolic calcium concentrations that persisted in the absence of extracellular calcium. The observed calcium-dependent peptidase activity was greatly inhibited by specific cysteine protease inhibitor E-64 and by the selective calpain inhibitor ALLN (N-acetyl-l-leucyl-l-leucyl-l-norleucinal). Taken together, we observed that intracellular Pf-calpain can be selectively detected and is the main calcium-dependent protease in the intraerythrocytic stages of the parasite. The method described here can be helpful in cell metabolism studies and antimalarial drug screening.

Targeting Plasmodium falciparum protein kinases with adenosine analogue-oligoarginine conjugates.

During the last decade, a vast number of inhibitors, ligands and fluorescent probes have evolved for mammalian protein kinases; however, the suitability of these compounds for studies of evolutionarily divergent eukaryotes has mostly been left beyond the scope of research. Here, we examined whether adenosine analogue-oligoarginine conjugates that had been extensively characterized as efficient inhibitors of the human protein kinases are applicable for targeting Plasmodium protein kinases. We demonstrated that ARCs were not only able to bind to and inhibit a representative member of Plasmodium falciparum kinome (cGMP-dependent protein kinase) in biochemical assay, but also affected the general phosphorylation levels in parasites released from the infected red blood cells upon saponin treatment. These findings urge advantaging of already existing biochemical tools, whose initially generic, but intrinsically "tunable" selectivity profiles could be used for dissection of signaling pathways outside the initially defined group of biological targets.

Extracellular ATP triggers proteolysis and cytosolic Ca²âº rise in Plasmodium berghei and Plasmodium yoelii malaria parasites.

BACKGROUND: Plasmodium has a complex cell biology and it is essential to dissect the cell-signalling pathways underlying its survival within the host. METHODS: Using the fluorescence resonance energy transfer (FRET) peptide substrate Abz-AIKFFARQ-EDDnp and Fluo4/AM, the effects of extracellular ATP on triggering proteolysis and Ca²âº signalling in Plasmodium berghei and Plasmodium yoelii malaria parasites were investigated. RESULTS: The protease activity was blocked in the presence of the purinergic receptor blockers suramin (50 µM) and PPADS (50 µM) or the extracellular and intracellular calcium chelators EGTA (5 mM) and BAPTA/AM (25, 100, 200 and 500 µM), respectively for P. yoelii and P. berghei. Addition of ATP (50, 70, 200 and 250 µM) to isolated parasites previously loaded with Fluo4/AM in a Ca²âº-containing medium led to an increase in cytosolic calcium. This rise was blocked by pre-incubating the parasites with either purinergic antagonists PPADS (50 µM), TNP-ATP (50 µM) or the purinergic blockers KN-62 (10 µM) and Ip5I (10 µM). Incubating P. berghei infected cells with KN-62 (200 µM) resulted in a changed profile of merozoite surface protein 1 (MSP1) processing as revealed by western blot assays. Moreover incubating P. berghei for 17 h with KN-62 (10 µM) led to an increase in rings forms (82% ± 4, n = 11) and a decrease in trophozoite forms (18% ± 4, n = 11). CONCLUSIONS: The data clearly show that purinergic signalling modulates P. berghei protease(s) activity and that MSP1 is one target in this pathway.