Extracellular Vesicles from Different Sources of Mesenchymal Stromal Cells Have Distinct Effects on Lung and Distal Organs in Experimental Sepsis.

The effects of the administration of mesenchymal stromal cells (MSC) may vary according to the source. We hypothesized that MSC-derived extracellular vesicles (EVs) obtained from bone marrow (BM), adipose (AD), or lung (L) tissues may also lead to different effects in sepsis. We profiled the proteome from EVs as a first step toward understanding their mechanisms of action. Polymicrobial sepsis was induced in C57BL/6 mice by cecal ligation and puncture (SEPSIS) and SHAM (control) animals only underwent laparotomy. Twenty-four hours after surgery, animals in the SEPSIS group were randomized to receive saline or 3 × 106 MSC-derived EVs from BM, AD, or L. The diffuse alveolar damage was decreased with EVs from all three sources. In kidneys, BM-, AD-, and L-EVs reduced edema and expression of interleukin-18. Kidney injury molecule-1 expression decreased only in BM- and L-EVs groups. In the liver, only BM-EVs reduced congestion and cell infiltration. The size and number of EVs from different sources were not different, but the proteome of the EVs differed. BM-EVs were enriched for anti-inflammatory proteins compared with AD-EVs and L-EVs. In conclusion, BM-EVs were associated with less organ damage compared with the other sources of EVs, which may be related to differences detected in their proteome.

Albumin Expands Albumin Reabsorption Capacity in Proximal Tubule Epithelial Cells through a Positive Feedback Loop between AKT and Megalin.

Renal proximal tubule cells (PTECs) act as urine gatekeepers, constantly and efficiently avoiding urinary protein waste through receptor-mediated endocytosis. Despite its importance, little is known about how this process is modulated in physiologic conditions. Data suggest that the phosphoinositide-3-kinase (PI3K)/protein kinase B (AKT) pathway regulates PTEC protein reabsorption. Here, we worked on the hypothesis that the physiologic albumin concentration and PI3K/AKT pathway form a positive feedback loop to expand endocytic capacity. Using LLC-PK1 cells, a model of PTECs, we showed that the PI3K/AKT pathway is required for megalin recycling and surface expression, affecting albumin uptake. Inhibition of this pathway stalls megalin at EEA1+ endosomes. Physiologic albumin concentration (0.01 mg/mL) activated AKT; this depends on megalin-mediated albumin endocytosis and requires previous activation of PI3K/mTORC2. This effect is correlated to the increase in albumin endocytosis, a phenomenon that we refer to as "albumin-induced albumin endocytosis". Mice treated with L-lysine present decreased albumin endocytosis leading to proteinuria and albuminuria associated with inhibition of AKT activity. Renal cortex explants obtained from control mice treated with MK-2206 decreased albumin uptake and promoted megalin internalization. Our data highlight the mechanism behind the capacity of PTECs to adapt albumin reabsorption to physiologic fluctuations in its filtration, avoiding urinary excretion.

BKCa Channel Activation Attenuates the Pathophysiological Progression of Monocrotaline-Induced Pulmonary Arterial Hypertension in Wistar Rats.

PURPOSE: In the present study, the therapeutic efficacy of a selective BKCa channel opener (compound X) in the treatment of monocrotaline (MCT)-induced pulmonary arterial hypertension (PAH) was investigated. METHODS: PAH was induced in male Wistar rats by a single injection of MCT. After two weeks, the MCT-treated group was divided into two groups that were either treated with compound X or vehicle. Compound X was administered daily at 28 mg/kg. Electrocardiographic, echocardiographic, and haemodynamic analyses were performed; ex vivo evaluations of pulmonary artery reactivity, right ventricle (RV) and lung histology as well as expression levels of α and ß myosin heavy chain, brain natriuretic peptide, and cytokines (TNFα and IL10) in heart tissue were performed. RESULTS: Pulmonary artery rings of the PAH group showed a lower vasodilatation response to acetylcholine, suggesting endothelial dysfunction. Compound X promoted strong vasodilation in pulmonary artery rings of both control and MCT-induced PAH rats. The untreated hypertensive rats presented remodelling of pulmonary arterioles associated with increased resistance to pulmonary flow; increased systolic pressure, hypertrophy and fibrosis of the RV; prolongation of the QT and Tpeak-Tend intervals (evaluated during electrocardiogram); increased lung and liver weights; and autonomic imbalance with predominance of sympathetic activity. On the other hand, treatment with compound X reduced pulmonary vascular remodelling, pulmonary flow resistance and RV hypertrophy and afterload. CONCLUSION: The use of a selective and potent opener to activate the BKCa channels promoted improvement of haemodynamic parameters and consequent prevention of RV maladaptive remodelling in rats with MCT-induced PAH.

Type 2 diabetes mellitus alters cardiac mitochondrial content and function in a non-obese mice model.

Type 2 diabetes mellitus (T2DM) is associated with an increase of premature appearance of several disorders such as cardiac complications. Thus, we test the hypothesis that a combination of a high fat diet (HFD) and low doses of streptozotocin (STZ) recapitulate a suitable mice model of T2DM to study the cardiac mitochondrial disturbances induced by this disease. Animals were divided in 2 groups: the T2DM group was given a HFD and injected with 2 low doses of STZ, while the CNTRL group was given a standard chow and a buffer solution. The combination of HFD and STZ recapitulate the T2DM metabolic profile showing higher blood glucose levels in T2DM mice when compared to CNTRL, and also, insulin resistance. The kidney structure/function was preserved. Regarding cardiac mitochondrial function, in all phosphorylative states, the cardiac mitochondria from T2DM mice presented reduced oxygen fluxes when compared to CNTRL mice. Also, mitochondria from T2DM mice showed decreased citrate synthase activity and lower protein content of mitochondrial complexes. Our results show that in this non-obese T2DM model, which recapitulates the classical metabolic alterations, mitochondrial function is impaired and provides a useful model to deepen study the mechanisms underlying these alterations.

O-GlcNAcylation reduces proximal tubule protein reabsorption and promotes proteinuria in spontaneously hypertensive rats.

Hypertensive individuals are at greater risk for developing chronic kidney disease (CKD). Reducing proteinuria has been suggested as a possible therapeutic approach to treat CKD. However, the mechanisms underlying the development of proteinuria in hypertensive conditions are incompletely understood. Cardiac and vascular dysfunction is associated with changes in the O-GlcNAcylation pathway in hypertensive models. We hypothesized that O-GlcNAcylation is also involved in renal damage, especially development of proteinuria, associated with hypertension. Using the spontaneously hypertensive rat (SHR) model, we observed higher renal cortex O-GlcNAcylation, glutamine-fructose aminotransferase (GFAT), and O-GlcNAc transferase (OGT) protein expression, which positively correlated with proteinuria. Interestingly, this was observed in hypertensive, but not pre-hypertensive, rats. Pharmacological inhibition of GFAT decreased renal cortex O-GlcNAcylation, proteinuria, and albuminuria in SHR. Using a proximal tubule cell line, we observed that increased O-GlcNAcylation reduced megalin surface expression and albumin endocytosis in vitro, and the effects were correlated in vivo Moreover, megalin is O-GlcNAcylated both in vitro and in vivo In conclusion, our results demonstrate a new mechanism involved in hypertension-associated proteinuria.

PKB is a central molecule in the modulation of Na+-ATPase activity by albumin in renal proximal tubule cells.

Evidence points to a possible role of tubular sodium reabsorption in worsening renal injury. Proximal tubule (PT) albumin overload is a critical process in the development of tubule-interstitial injury (TII), and consequently in progression of renal disease. We studied the possible correlation between changes in albumin concentration in the lumen of PT with modification of Na+-ATPase activity. An albumin overload animal model and LLC-PK1 cells as a model of PT cells were used. Albumin overload was induced by intraperitoneal injection of BSA in 14-week-old male Wistar rats. An increase in sodium clearance, fractional excretion of sodium, proteinuria, ratio between urinary protein and creatinine, and albuminuria were observed. These observations indicate that there could be a correlation between an increase in albumin in the lumen of PTs and renal sodium excretion. We observed that the activity of both Na+-ATPase and (Na++K+)ATPase decreased in the renal cortex of an albumin overload animal model. Using LLC-PK1 cells as a model of PT cells, inhibition of Na+-ATPase activity was observed with higher albumin concentrations, similar to that observed in the animal model. The inhibition of protein kinase B by higher albumin concentration was found to be a critical step in the inhibition of Na+-ATPase activity. Interestingly, activation of the ERK1/2/mTORC1/S6K pathway was required for protein kinase B inhibition. This mechanism leads to a decrease in protein kinase C activity and, consequently to inhibition of Na+-ATPase activity. Taken together, our results indicate that the molecular mechanism underlying the modulation of PT Na+-ATPase activity by albumin overload involves activation of the ERK1/2/mTORC1/S6K pathway, which leads to inhibition of the mTORC2/PKB/PKC pathway. Our findings contribute to better understanding regarding handing of renal Na+ induced by albumin overload in the lumen of PTs and, consequently, in the progression of renal disease.

Environmental obesogen tributyltin chloride leads to abnormal hypothalamic-pituitary-gonadal axis function by disruption in kisspeptin/leptin signaling in female rats.

Tributyltin chloride (TBT) is a xenobiotic used as a biocide in antifouling paints that has been demonstrated to induce endocrine-disrupting effects, such as obesity and reproductive abnormalities. An integrative metabolic control in the hypothalamus-pituitary-gonadal (HPG) axis was exerted by leptin. However, studies that have investigated the obesogenic TBT effects on the HPG axis are especially rare. We investigated whether metabolic disorders as a result of TBT are correlated with abnormal hypothalamus-pituitary-gonadal (HPG) axis function, as well as kisspeptin (Kiss) action. Female Wistar rats were administered vehicle and TBT (100ng/kg/day) for 15days via gavage. We analyzed their effects on the tin serum and ovary accumulation (as biomarker of TBT exposure), estrous cyclicity, surge LH levels, GnRH expression, Kiss action, fertility, testosterone levels, ovarian apoptosis, uterine inflammation, fibrosis, estrogen negative feedback, body weight gain, insulin, leptin, adiponectin levels, as well as the glucose tolerance (GTT) and insulin sensitivity tests (IST). TBT led to increased serum and ovary tin levels, irregular estrous cyclicity, and decreased surge LH levels, GnRH expression and Kiss responsiveness. A strong negative correlation between the serum and ovary tin levels with lower Kiss responsiveness and GnRH mRNA expression was observed in TBT rats. An increase in the testosterone levels, ovarian and uterine fibrosis, ovarian apoptosis, and uterine inflammation and a decrease in fertility and estrogen negative feedback were demonstrated in the TBT rats. We also identified an increase in the body weight gain and abnormal GTT and IST tests, which were associated with hyperinsulinemia, hyperleptinemia and hypoadiponectinemia, in the TBT rats. TBT disrupted proper functioning of the HPG axis as a result of abnormal Kiss action. The metabolic dysfunctions co-occur with the HPG axis abnormalities. Hyperleptinemia as a result of obesity induced by TBT may be associated with abnormal HPG function. A strong negative correlation between the hyperleptinemia and lower Kiss responsiveness was observed in the TBT rats. These findings provide evidence that TBT leads to toxic effects direct on the HPG axis and/or indirectly by abnormal metabolic regulation of the HPG axis.

The Effects of Dasatinib in Experimental Acute Respiratory Distress Syndrome Depend on Dose and Etiology.

BACKGROUND/AIMS: Evidence suggests that tyrosine-kinase inhibitors may attenuate lung inflammation and fibrosis in experimental acute respiratory distress syndrome (ARDS). We hypothesized that dasatinib, a tyrosine-kinase inhibitor, might act differently depending on the ARDS etiology and the dose. METHODS: C57/BL6 mice were divided to be pre-treated with dasatinib (1mg/kg or 10mg/kg) or vehicle (1% dimethyl-sulfoxide) by oral gavage. Thirty-minutes after pre-treatment, mice were subdivided into control (C) or ARDS groups. ARDS animals received Escherichia coli lipopolysaccharide intratracheally (ARDSp) or intraperitoneally (ARDSexp). A new dose of dasatinib or vehicle was administered at 6 and 24h. RESULTS: Forty-eight hours after ARDS induction, dasatinib 1mg/kg yielded: improved lung morphofunction and reduced cells expressing toll-like receptor (TLR)-4 in lung, independent of ARDS etiology; reduced neutrophil and levels of interleukin (IL)-6, IL-10 and transforming growth factor (TGF)-ß in ARDSp. The higher dose of dasatinib caused no changes in lung mechanics, diffuse alveolar damage, neutrophil, or cells expressing TLR4, but increased IL-6, vascular endothelial growth factor (VEGF), and cells expressing Fas receptor in lung in ARDSp. In ARDSexp, it improved lung morphofunction, increased VEGF, and reduced cells expressing TLR4. Conclusion: Dasatinib may have therapeutic potential in ARDS independent of etiology, but careful dose monitoring is required.

Early withdrawal of calcineurin inhibitor from a sirolimus-based immunosuppression stabilizes fibrosis and the transforming growth factor-ß signalling pathway in kidney transplant.

AIM: The focus in renal transplantation is to increase long-term allograft survival. One of the limiting factors is calcineurin inhibitor (CNI)-induced fibrosis. This study attempted to examine the histological aspect of interstitial fibrosis and the modulation of the transforming growth factor-ß (TGF-ß) canonical signalling pathway following early withdrawal of CNI from sirolimus-based immunosuppressive therapy. METHODS: Forty-five kidney transplant recipients with low-medium immunologic risk were randomized and underwent protocol biopsies obtained at the time of transplantation and at 3 and 12 months thereafter. The recipients were taking tacrolimus, sirolimus and prednisone. After the 3rd month, patients were randomized into two groups: sirolimus (SRL) (removed CNI and increased sirolimus) and tacrolimus (TAC) (maintained CNI). Renal biopsies were analyzed according to Banff's 2007 criteria. The sum of Banff's ct and ci constituted the chronicity index. Fibrosis was evaluated by the histomorphometrical analysis of the total collagen and myofibroblast deposition. Immunohistochemical characterization and quantification of TGF-ß, TGF-ß receptor 1 (TGF-ß-R1), receptor 2 (TGF-ß-R2) and phospho-Smad2/3 (p-Smad2/3) were performed. RESULTS: Maintenance of CNI was associated with the increase of the surface density of collagen and α-smooth muscle actin (α-SMA), (P = 0.001). Furthermore, increased TGF-ß (P = 0.02), TGF-ß-R1 (P = 0.02), p-Smad2/3 (P = 0.03) and stabilized TGF-ß-R2. On the other hand, the removal of CNI with increase in the dose of sirolimus limited the enhancement of the chronicity index at 12 m (SRL, 2.18 vs TAC, 3.12, P = 0.0007), diminished the deposition of fibrosis and promoted the stabilization of TGF-ß, TGF-ß-R2, p-Smad2/3 and myofibroblasts as well as the reduction of TGF-ß-R1 (P = 0.01). CONCLUSION: The early withdrawal of CNI limited the fibrosis progression through the stabilization of chronicity index and of the canonical TGF-ß signalling pathway.

Repeated administration of bone marrow-derived cells prevents disease progression in experimental silicosis.

BACKGROUND/AIMS: Bone marrow-derived cells (BMDCs) reduced mechanical and histologic changes in the lung in a murine model of silicosis, but these beneficial effects did not persist in the course of lung injury. We hypothesized that repeated administration of BMDCs may decrease lung inflammation and remodeling thus preventing disease progression. METHODS: One hundred and two C57BL/6 mice were randomly divided into SIL (silica, 20 mg intratracheally [IT]) and control (C) groups (saline, IT). C and SIL groups were further randomized to receive BMDCs (2×10(6) cells) or saline IT 15 and 30 days after the start of the protocol. RESULTS: By day 60, BMDCs had decreased the fractional area of granuloma and the number of polymorphonuclear cells, macrophages (total and M1 phenotype), apoptotic cells, the level of transforming growth factor (TGF)-ß' and types I and III collagen fiber content in the granuloma. In the alveolar septa, BMDCs reduced the amount of collagen and elastic fibers, TGF-ß, and the number of M1 and apoptotic cells. Furthermore, interleukin (IL)-1ß, IL-1R1, caspase-3 mRNA levels decreased and the level of IL-1RN mRNA increased. Lung mechanics improved after BMDC therapy. The presence of male donor cells in lung tissue was not observed using detection of Y chromosome DNA. CONCLUSION: repeated administration of BMDCs reduced inflammation, fibrogenesis, and elastogenesis, thus improving lung mechanics through the release of paracrine factors.

Bone marrow-derived mononuclear cells promote improvement in glomerular function in rats with early diabetic nephropathy.

BACKGROUND/AIMS: Diabetic nephropathy is one of the main causes of end-stage renal disease. The present study investigated the effect of mononuclear cell (MC) therapy in rats subjected to diabetic nephropathy. METHODS: Male Wistar rats were divided into control (CTRL), diabetic (DM), CTRL+MC and DM+MC groups. Diabetes was induced by a single injection of streptozotocin (45 mg/kg, i.p.) and, 4 weeks later, 2×10(7) MCs were injected via the jugular vein. RESULTS: The rats in the DM and DM+MC groups showed increased glycemia, glomerular filtration rate and glomerular tuff area versus control groups. The glomerular filtration rate and glomerular tuff area were normalized in the DM+MC group. No alterations were observed in the fractional excretion of electrolytes and proteinuria between the DM and DM+MC groups. TGF-ß1 protein levels in the DM group were significantly increased versus control animals and normalized in the DM+MC group. An increase in ED1(+)/arginase I(+) macrophages and IL-10 renal expression was observed in the DM+MC group versus DM group. CONCLUSIONS: Bone marrow-derived MC therapy was able to prevent glomerular alterations and TGF-ß1 protein overexpression and modulated glomerular arginase I(+) macrophage infiltration in rats subjected to early diabetic nephropathy.

Rapamycin treatment induces tubular proteinuria: role of megalin-mediated protein reabsorption.

Introduction: Rapamycin is an immunosuppressor that acts by inhibiting the serine/threonine kinase mechanistic target of rapamycin complex 1. Therapeutic use of rapamycin is limited by its adverse effects. Proteinuria is an important marker of kidney damage and a risk factor for kidney diseases progression and has been reported in patients and animal models treated with rapamycin. However, the mechanism underlying proteinuria induced by rapamycin is still an open matter. In this work, we investigated the effects of rapamycin on parameters of renal function and structure and on protein handling by proximal tubule epithelial cells (PTECs). Methods: Healthy BALB/c mice were treated with 1.5 mg/kg rapamycin by oral gavage for 1, 3, or 7 days. At the end of each treatment, the animals were kept in metabolic cages and renal function and structural parameters were analyzed. LLC-PK1 cell line was used as a model of PTECs to test specific effect of rapamycin. Results: Rapamycin treatment did not change parameters of glomerular structure and function. Conversely, there was a transient increase in 24-h proteinuria, urinary protein to creatinine ratio (UPCr), and albuminuria in the groups treated with rapamycin. In accordance with these findings, rapamycin treatment decreased albumin-fluorescein isothiocyanate uptake in the renal cortex. This effect was associated with reduced brush border expression and impaired subcellular distribution of megalin in PTECs. The effect of rapamycin seems to be specific for albumin endocytosis machinery because it did not modify renal sodium handling or (Na++K+)ATPase activity in BALB/c mice and in the LLC-PK1 cell line. A positive Pearson correlation was found between megalin expression and albumin uptake while an inverse correlation was shown between albumin uptake and UPCr or 24-h proteinuria. Despite its effect on albumin handling in PTECs, rapamycin treatment did not induce tubular injury measured by interstitial space and collagen deposition. Conclusion: These findings suggest that proteinuria induced by rapamycin could have a tubular rather than a glomerular origin. This effect involves a specific change in protein endocytosis machinery. Our results open new perspectives on understanding the undesired effect of proteinuria generated by rapamycin.

Early effects of bone marrow-derived mononuclear cells on lung and kidney in experimental sepsis.

BACKGROUND: In experimental sepsis, functional and morphological effects of bone marrow-derived mononuclear cell (BMDMC) administration in lung tissue have been evaluated 1 and 7 days after therapy. However, to date no study has evaluated the early effects of BMDMCs in both lung and kidney in experimental polymicrobial sepsis. MATERIAL AND METHODS: Twenty-five female C57BL/6 mice were randomly divided into the following groups: 1) cecal ligation and puncture (CLP)-induced sepsis; and 2) Sham (surgical procedure without CLP). After 1 h, CLP animals received saline (NaCl 0.9%) (CLP-Saline) or 106 BMDMCs (CLP-Cell) via the jugular vein. At 6, 12, and 24 h after saline or BMDMC administration, lungs and kidneys were removed for histology and molecular biology analysis. RESULTS: In lungs, CLP-Saline, compared to Sham, was associated with increased lung injury score (LIS) and keratinocyte chemoattractant (KC) mRNA expression at 6, 12, and 24 h. BMDMCs were associated with reduced LIS and KC mRNA expression regardless of the time point of analysis. Interleukin (IL)- 10 mRNA content was higher in CLP-Cell than CLP-Saline at 6 and 24 h. In kidney tissue, CLP-Saline, compared to Sham, was associated with tubular cell injury and increased neutrophil gelatinase-associated lipocalin (NGAL) levels, which were reduced after BMDMC therapy at all time points. Surface high-mobility-group-box (HMGB)- 1 levels were higher in CLP-Saline than Sham at 6, 12, and 24 h, whereas nuclear HMGB-1 levels were increased only at 24 h. BMDMCs were associated with decreased surface HMGB-1 and increased nuclear HMGB-1 levels. Kidney injury molecule (KIM)- 1 and IL-18 gene expressions were reduced in CLP-Cell compared to CLP-Saline at 12 and 24 h. CONCLUSION: In the present experimental polymicrobial sepsis, early intravenous therapy with BMDMCs was able to reduce lung and kidney damage in a time-dependent manner. BMDMCs thus represent a potential therapy in well-known scenarios of sepsis induction. PURPOSE: To evaluate early bone marrow-derived mononuclear cell (BMDMC) therapy on lung and kidney in experimental polymicrobial sepsis. METHODS: Twenty-five female C57BL/6 mice were randomly divided into the following groups: cecal ligation and puncture (CLP)-induced sepsis; and sham (surgical procedure without CLP). After 1 h, CLP animals received saline (CLP-saline) or 106 BMDMCs (CLP-cell) via the jugular vein. Lungs and kidneys were evaluated for histology and molecular biology after 6, 12, and 24 h. RESULTS: In lungs, BMDMCs reduced the lung injury score and keratinocyte chemoattractant mRNA expression regardless of the time point of analysis; interleukin-10 mRNA content was higher in CLP-cell than CLP-saline at 6 and 24 h. In kidneys, BMDMCs reduced neutrophil gelatinase-associated lipocalin levels at all time points. BMDMCs decreased surface high mobility group box (HMGB)- 1 but increased nuclear HMGB-1 levels. CONCLUSION: Early BMDMC therapy reduced lung and kidney damage in a time-dependent manner.

Adipose Tissue-Derived Mesenchymal Stromal Cells from Ex-Morbidly Obese Individuals Instruct Macrophages towards a M2-Like Profile In Vitro.

Obesity, which continues to increase worldwide, was shown to irreversibly impair the differentiation potential and angiogenic properties of adipose tissue mesenchymal stromal cells (ADSCs). Because these cells are intended for regenerative medicine, especially for the treatment of inflammatory conditions, and the effects of obesity on the immunomodulatory properties of ADSCs are not yet clear, here we investigated how ADSCs isolated from former obese subjects (Ex-Ob) would influence macrophage differentiation and polarization, since these cells are the main instructors of inflammatory responses. Analysis of the subcutaneous adipose tissue (SAT) of overweight (OW) and Ex-Ob subjects showed the maintenance of approximately twice as many macrophages in Ex-Ob SAT, contained within the CD68＋/FXIII-A- inflammatory pool. Despite it, in vitro, coculture experiments revealed that Ex-Ob ADSCs instructed monocyte differentiation into a M2-like profile, and under inflammatory conditions induced by LPS treatment, inhibited HLA-DR upregulation by resting M0 macrophages, originated a similar percentage of TNF-α＋ cells, and inhibited IL-10 secretion, similar to OW-ADSCs and BMSCs, which were used for comparison, as these are the main alternative cell types available for therapeutic purposes. Our results showed that Ex-Ob ADSCs mirrored OW-ADSCs in macrophage education, favoring the M2 immunophenotype and a mixed (M1/M2) secretory response. These results have translational potential, since they provide evidence that ADSCs from both Ex-Ob and OW subjects can be used in regenerative medicine in eligible therapies. Further in vivo studies will be fundamental to validate these observations.

(Na+ + K+)-ATPase is a target for phosphoinositide 3-kinase/protein kinase B and protein kinase C pathways triggered by albumin.

In recent decades, evidence has confirmed the crucial role of albumin in the progression of renal disease. However, the possible role of signaling pathways triggered by physiologic concentrations of albumin in the modulation of proximal tubule (PT) sodium reabsorption has not been considered. In the present work, we have shown that a physiologic concentration of albumin increases the expression of the α1 subunit of (Na(+) + K(+))-ATPase in LLC-PK1 cells leading to an increase in enzyme activity. This process involves the sequential activation of PI3K/protein kinase B and protein kinase C pathways promoting inhibition of protein kinase A. This integrative network is inhibited when albumin concentration is increased, similar to renal disease, leading to a decrease in the α1 subunit of (Na(+) + K(+))-ATPase expression. Together, the results indicate that variation in albumin concentration in PT cells has an important effect on PT sodium reabsorption and, consequently, on renal sodium excretion.

Role of estrogen and progesterone in the modulation of CNG-A1 and Na/K+-ATPase expression in the renal cortex.

The steroid hormones, estrogen and progesterone, are involved mainly in the control of female reproductive functions. Among other effects, estrogen and progesterone can modulate Na(+) reabsorption along the nephron altering the body's hydroelectrolyte balance. In this work, we analyzed the expression of cyclic nucleotide-gated channel A1 (CNG-A1) and α1 Na(+)/K(+)-ATPase subunit in the renal cortex and medulla of female ovariectomized rats and female ovariectomized rats subjected to 10 days of 17ß-estradiol benzoate (2.0 µg/kg body weight) and progesterone (1.7 mg/kg body weight) replacement. Na(+)/K(+) ATPase activity was also measured. Immunofluorescence localization of CNG-A1 in the cortex and medulla was performed in control animals. We observed that CNG-A1 is localized at the basolateral membrane of proximal and distal tubules. Female ovariectomized rats showed low expression of CNG-A1 and low expression and activity of Na(+)/K(+) ATPase in the renal cortex. When female ovariectomized rats were subjected to 17ß-estradiol benzoate replacement, normalization of CNG-A1 expression and Na(+)/K(+) ATPase expression and activity was observed. The replacement of progesterone was not able to recover CNG-A1 expression and Na(+)/K(+) ATPase expression at the control level. Only the activity of Na(+)/K(+) ATPase was able to be recovered at control levels in animals subjected to progesterone replacement. No changes in expression and activity were observed in the renal medulla. The expression of CNG-A1 is higher in cortex compared to medulla. In this work, we observed that estrogen and progesterone act in renal tissues modulating CNG-A1 and Na(+)/K(+) ATPase and these effects could be important in Na(+) and water balance.

Proinflammatory clearance of apoptotic neutrophils induces an IL-12(low)IL-10(high) regulatory phenotype in macrophages.

Clearance of apoptotic exudate neutrophils (efferocytosis) induces either pro- or anti-inflammatory responses in mouse macrophages depending on host genetic background. In this study, we investigated whether neutrophil efferocytosis induces a stable macrophage phenotype that could be recalled by late restimulation with LPS. Bone marrow-derived macrophages previously stimulated by pro- but not anti-inflammatory neutrophil efferocytosis expressed a regulatory/M2b phenotype characterized by low IL-12 and high IL-10 production following restimulation, increased expression of LIGHT/TNF superfamily 14, Th2-biased T cell responses, and permissive replication of Leishmania major. Induction of regulatory/M2b macrophages required neutrophil elastase activity and was partially dependent on TLR4 signaling. These results suggested that macrophage differentiation to a regulatory phenotype plays a role in resolution of inflammation but could contribute to increased humoral Ab responses and parasite persistence in the infected host.

Growth of an aggressive tumor during pregnancy in an acromegalic patient.

Pregnancy in acromegalic patients is a rare event, but is usually uneventful, with stable GH and IGF-I levels and no tumor enlargement. Medical treatment can usually be withdrawn without problems and although no major adverse event has been reported, the suspension of drug treatments is generally recommended. No case report exists in the literature regarding evolution of a somatotropinoma with invasiveness markers throughout pregnancy. We report a case of an acromegalic patient who was submitted to surgery and treated with octreotide LAR maintaining a stable residual tumor and an IGF-I close to the normal levels. Her tumor presented with a high Ki-67 (11.6%) and a low aryl hydrocarbon receptor-interacting protein (AIP) expression. When she became pregnant, octreotide LAR was withdrawn, and despite remaining asymptomatic during pregnancy, tumor growth occurred with compression of surrounding structures. In conclusion, pregnancy in acromegalic patients has usually a favorable prognosis with no tumor growth. However, in the presence of high Ki-67 labeling index and low AIP expression, tumor enlargement may occur and somatostatin analogue treatment throughout the pregnancy should be considered.

Liver steatosis, cardiac and renal fibrosis, and hypertension in overweight rats: Angiotensin-(3-4)-sensitive hepatocardiorenal syndrome.

Overweight/obesity is a growing pandemic that affects many organs and tissues. We have investigated whether a high-lipid diet provokes an imbalance between type 1 and type 2 angiotensin II (Ang II) receptors signaling, leading to liver alterations associated with cardiovascular and kidney disturbances. Chronic administration of a high-lipid diet can provoke hepatocardiorenal syndrome resulting from activation of the Ang II→type 1 receptor axis, which is entirely counteracted by Ang-(3-4), the allosteric enhancer of the Ang II→type 2 receptor pathway.

Axl receptor induces efferocytosis, dampens M1 macrophage responses and promotes heart pathology in Trypanosoma cruzi infection.

Adaptive immunity controls Trypanosoma cruzi infection, but the protozoan parasite persists and causes Chagas disease. T cells undergo apoptosis, and the efferocytosis of apoptotic cells might suppress macrophages and exacerbate parasite infection. Nonetheless, the receptors involved in the efferocytosis of apoptotic lymphocytes during infection remain unknow. Macrophages phagocytose apoptotic cells by using the TAM (Tyro3, Axl, Mer) family of receptors. To address how the efferocytosis of apoptotic cells affects macrophage-mediated immunity, we employ here Axl receptor- and Mer receptor-deficient mouse strains. In bone marrow-derived macrophages (BMDMs), both Axl and Mer receptors play a role in the efferocytosis of proapoptotic T cells from T. cruzi-infected mice. Moreover, treatment with a TAM receptor inhibitor blocks efferocytosis and upregulates M1 hallmarks induced by immune T cells from infected mice. Remarkably, the use of Axl-/- but not Mer-/- macrophages increases T-cell-induced M1 responses, such as nitric oxide production and control of parasite infection. Furthermore, infected Axl-/- mice show reduced peak parasitemia, defective efferocytosis, improved M1 responses, and ameliorated cardiac inflammation and fibrosis. Therefore, Axl induces efferocytosis, disrupts M1 responses, and promotes parasite infection and pathology in experimental Chagas disease. Axl stands as a potential host-direct target for switching macrophage phenotypes in infectious diseases.