The angiotensin II/type 1 angiotensin II receptor pathway is implicated in the dysfunction of albumin endocytosis in renal proximal tubule epithelial cells induced by high glucose levels.

It is well-established that dysfunction of megalin-mediated albumin endocytosis by proximal tubule epithelial cells (PTECs) and the activation of the Renin-Angiotensin System (RAS) play significant roles in the development of Diabetic Kidney Disease (DKD). However, the precise correlation between these factors still requires further investigation. In this study, we aimed to elucidate the potential role of angiotensin II (Ang II), a known effector of RAS, as the mediator of albumin endocytosis dysfunction induced by high glucose (HG) in PTECs. To achieve this, we utilized LLC-PK1 and HK-2 cells, which are well-established in vitro models of PTECs. Using albumin-FITC or DQ-albumin as tracers, we observed that incubation of LLC-PK1 and HK-2 cells with HG (25 mM for 48 h) significantly reduced canonical receptor-mediated albumin endocytosis, primarily due to the decrease in megalin expression. HG increased the concentration of Ang II in the LLC-PK1 cell supernatant, a phenomenon associated with an increase in angiotensin-converting enzyme (ACE) expression and a decrease in prolyl carboxypeptidase (PRCP) expression. ACE type 2 (ACE2) expression remained unchanged. To investigate the potential impact of Ang II on HG effects, the cells were co-incubated with angiotensin receptor inhibitors. Only co-incubation with 10-7 M losartan (an antagonist for type 1 angiotensin receptor, AT1R) attenuated the inhibitory effect of HG on albumin endocytosis, as well as megalin expression. Our findings contribute to understanding the genesis of tubular albuminuria observed in the early stages of DKD, which involves the activation of the Ang II/AT1R axis by HG.

Toll like receptor 4 mediates the inhibitory effect of SARS-CoV-2 spike protein on proximal tubule albumin endocytosis.

Tubular proteinuria is a common feature in COVID-19 patients, even in the absence of established acute kidney injury. SARS-CoV-2 spike protein (S protein) was shown to inhibit megalin-mediated albumin endocytosis in proximal tubule epithelial cells (PTECs). Angiotensin-converting enzyme type 2 (ACE2) was not directly involved. Since Toll-like receptor 4 (TLR4) mediates S protein effects in various cell types, we hypothesized that TLR4 could be participating in the inhibition of PTECs albumin endocytosis elicited by S protein. Two different models of PTECs were used: porcine proximal tubule cells (LLC-PK1) and human embryonic kidney cells (HEK-293). S protein reduced Akt activity by specifically inhibiting of threonine 308 (Thr308) phosphorylation, a process mediated by phosphoinositide-dependent kinase 1 (PDK1). GSK2334470, a PDK1 inhibitor, decreased albumin endocytosis and megalin expression mimicking S protein effect. S protein did not change total TLR4 expression but decreased its surface expression. LPS-RS, a TLR4 antagonist, also counteracted the effects of the S protein on Akt phosphorylation at Thr308, albumin endocytosis, and megalin expression. Conversely, these effects of the S protein were replicated by LPS, an agonist of TLR4. Incubation of PTECs with a pseudovirus containing S protein inhibited albumin endocytosis. Null or VSV-G pseudovirus, used as control, had no effect. LPS-RS prevented the inhibitory impact of pseudovirus containing the S protein on albumin endocytosis but had no influence on virus internalization. Our findings demonstrate that the inhibitory effect of the S protein on albumin endocytosis in PTECs is mediated through TLR4, resulting from a reduction in megalin expression.

The Prolonged Activation of the p65 Subunit of the NF-Kappa-B Nuclear Factor Sustains the Persistent Effect of Advanced Glycation End Products on Inflammatory Sensitization in Macrophages.

Advanced glycation end products (AGEs) prime macrophages for lipopolysaccharide (LPS)-induced inflammation. We investigated the persistence of cellular AGE-sensitization to LPS, considering the nuclear content of p50 and p65 nuclear factor kappa B (NFKB) subunits and the expression of inflammatory genes. Macrophages treated with control (C) or AGE-albumin were rested for varying intervals in medium alone before being incubated with LPS. Comparisons were made using one-way ANOVA or Student t-test (n = 6). AGE-albumin primed macrophages for increased responsiveness to LPS, resulting in elevated levels of TNF, IL-6, and IL-1beta (1.5%, 9.4%, and 5.6%, respectively), compared to C-albumin. TNF, IL-6, and IL-1 beta secretion persisted for up to 24 h even after the removal of AGE-albumin (area under the curve greater by 1.6, 16, and 5.2 times, respectively). The expressions of Il6 and RelA were higher 8 h after albumin removal, and Il6 and Abca1 were higher 24 h after albumin removal. The nuclear content of p50 remained similar, but p65 showed a sustained increase (2.9 times) for up to 24 h in AGE-albumin-treated cells. The prolonged activation of the p65 subunit of NFKB contributes to the persistent effect of AGEs on macrophage inflammatory priming, which could be targeted for therapies to prevent complications based on the AGE-RAGE-NFKB axis.

Regionalized analysis of gut barrier components in the small intestine of BALB/c mice following chronic immobilization stress.

BACKGROUND: Microbiota and tight junction proteins (TJPs) are components of the gut barrier, and are considered stress targets that have deleterious effects on intestinal homeostasis. OBJECTIVES: This study aimed to evaluate the effects of chronic immobilization stress on selected small intestine homeostasis parameters. MATERIAL AND METHODS: Female BALB/c mice were divided into a stress group that underwent short-term immobilization for 2 h per day for 4 consecutive days, and a non-stressed control group (n = 6 per group). Proximal and distal small intestine samples were excised to assess colony-forming units per gram (CFU/g) of total bifidobacteria in selective agar plates, luminal albumin was assessed using immune-enzymatic assay, pro-inflammatory cytokines were evaluated using reverse transcription-quantitative polymerase chain reaction (RT-qPCR), and TJPs (pore-forming, claudin (Cld)-2; pore-sealing, Cld-4; ambiguous, Cld-7, -12 and -15) were assessed with RT-qPCR and western blotting. RESULTS: Compared with the control group, the stress group had lower body weight and energy intake. In the distal region, the stressed mice had lower bifidobacteria count and messenger ribonucleic acid (mRNA) expression of Cld-2, Cld-4 and Cld-12, though they had more albumin and higher interleukin (IL)-6 mRNA expression. Within the proximal region, the stressed mice had higher mRNA expression of tumor necrosis factor alpha (TNF-α), interferon gamma (IFN-γ), IL-6, Cld-7, Cld-12, and Cld-15, along with lower levels of IL-10 and Cld-4. However, mRNA and protein expression of TJPs were discordant. CONCLUSIONS: These findings indicate divergent stress-induced outcomes in the small intestine, evidenced by the elicitation of a pro-inflammatory response and decreased anti-inflammatory response in the duodenum, and by increased albumin transudation and decreased bifidobacterial growth in the distal region.

Gold nanoparticles reduce tubule-interstitial injury and proteinuria in a murine model of subclinical acute kidney injury.

Subclinical acute kidney injury (subAKI) is characterized by tubule-interstitial injury without significant changes in glomerular function. SubAKI is associated with the pathogenesis and progression of acute and chronic kidney diseases. Currently, therapeutic strategies to treat subAKI are limited. The use of gold nanoparticles (AuNPs) has shown promising benefits in different models of diseases. However, their possible effects on subAKI are still unknown. Here, we investigated the effects of AuNPs on a mouse model of subAKI. Animals with subAKI showed increased functional and histopathologic markers of tubular injury. There were no changes in glomerular function and structure. The animals with subAKI also presented an inflammatory profile demonstrated by activation of Th1 and Th17 cells in the renal cortex. This phenotype was associated with decreased megalin-mediated albumin endocytosis and expression of proximal tubular megalin. AuNP treatment prevented tubule-interstitial injury induced by subAKI. This effect was associated with a shift to an anti-inflammatory Th2 response. Furthermore, AuNP treatment preserved megalin-mediated albumin endocytosis in vivo and in vitro. AuNPs were not nephrotoxic in healthy mice. These results suggest that AuNPs have a protective effect in the tubule-interstitial injury observed in subAKI, highlighting a promising strategy as a future antiproteinuric treatment.

Inhibition of SGLT2 co-transporter by dapagliflozin ameliorates tubular proteinuria and tubule-interstitial injury at the early stage of diabetic kidney disease.

Diabetic kidney disease (DKD) is characterized by progressive impairment of kidney function. It has been postulated that tubule-interstitial injury, associated with tubular albuminuria, precedes glomerular damage in the early stage of DKD. Here, we wanted to determine if the development of tubule-interstitial injury at the early stage of DKD implies modulation of megalin-mediated protein reabsorption in proximal tubule epithelial cells (PTECs) by SGLT2-dependent high glucose influx. Rats with streptozotocin (STZ)-induced diabetes were treated or not with dapagliflozin (DAPA) for 8 weeks. Four experimental groups were generated: (1) CONT, control; (2) DAPA, rats treated with DAPA; (3) STZ, diabetic rats; (4) STZ + DAPA, diabetic rats treated with DAPA. No changes in glomerular structure and function were observed. The STZ group presented proteinuria and albuminuria associated with an increase in the fractional excretion of proteins. A positive correlation between glycemia and proteinuria was found. These phenomena were linked to a decrease in luminal and total megalin expression and, consequently, in albumin reabsorption in PTECs. We also observed tubule-interstitial injury characterized by an increase in urinary tubular injury biomarkers and changes in tubular histomorphometry parameters. In addition, inverse correlations were found between cortical albumin uptake and tubule-interstitial injury or glycemia. All these modifications were attenuated in the STZ + DAPA group. These results suggest that SGLT2-dependent high glucose influx into PTECs promotes a harmful effect on the PTECs, leading to the development of tubular albuminuria and tubule-interstitial injury preceding glomerular damage. These results expand current knowledge on the renoprotective effects of gliflozins.

The nephroprotective action of Passiflora edulis in streptozotocin-induced diabetes.

In the present study, we aimed to evaluate the therapeutic effect of Passiflora edulis fruit peel aqueous (AFA) extract as an adjuvant to insulin to confer nephroprotection against streptozotocin-induced diabetes. Male Wistar rats were divided into four groups based on treatment received for 60 days: diabetic (DB), control (CTL), insulin (INS), and insulin + AFA extract (INS + AFA). mRNA and protein expression levels of podocyte (nephrin, podocin, and WT1) and tubular (megalin) proteins were measured in kidney tissue specimens and urine. Biochemical parameters and kidney histopathology were also examined. Herein, the INS + AFA group showed superior glycemic control, which resulted in the reduction of urinary albumin/creatinine ratio, maintenance of baseline levels of Nphs1, Nphs2, Wt1, and Lrp2 mRNA expression, prevention of protein loss from the kidney tissue into the urinary space, along with the maintenance of glomerular basement membrane thickness, hyalinization, glomerular and tubulointerstitial fibrosis at values approximating those of the CTL group and significantly lower than those in the DB group. Therefore, these results suggest that, as an anti-diabetic agent, the AFA extract adjuvant to insulin could reduce and potentially prevent diabetic kidney disease.

Acute Methylglyoxal-Induced Damage in Blood-Brain Barrier and Hippocampal Tissue.

Methylglyoxal (MG) is a reactive dicarbonyl compound formed mostly via the glycolytic pathway. Elevated blood glucose levels can cause MG accumulation in plasma and cerebrospinal fluid in patients with diabetes mellitus and Alzheimer's disease. Under these disease conditions, the high reactivity of MG leads to modification of proteins and other biomolecules, generating advanced glycation end products (AGEs), which are considered mediators in neurodegenerative diseases. We investigated the integrity of the blood-brain barrier (BBB) and astrocyte response in the hippocampus to acute insult induced by MG when it was intracerebroventricularly administered to rats. Seventy-two hours later, BBB integrity was lost, as assessed by the entry of Evans dye into the brain tissue and albumin in the cerebrospinal fluid, and a decrease in aquaporin-4 and connexin-43 in the hippocampal tissue. MG did not induce changes in the hippocampal contents of RAGE in this short interval, but decreased the expression of S100B, an astrocyte-secreted protein that binds RAGE. The expression of two important transcription factors of the antioxidant response, NF-κB and Nrf2, was unchanged. However, hemeoxigenase-1 was upregulated in the MG-treated group. These data corroborate the idea that hippocampal cells are targets of MG toxicity and that BBB dysfunction and specific glial alterations induced by this compound may contribute to the behavioral and cognitive alterations observed in these animals.

Antioxidant extract of black rice prevents renal dysfunction and renal fibrosis caused by ethanol-induced toxicity.

This study was conducted to evaluate the protective role of extracted natural antioxidants from black rice and their effect on kidney failure and renal cirrhosis caused by ethanol-induced toxicity. Antioxidant activity in terms of total phenol content, flavonoid compounds and anthocyanin, as well as antioxidant capacity, was determined in an extract of black rice. The findings noted that the black rice extract contained high amounts of antioxidant activity and capacity. Total phenolic compounds from black rice extract were fractionated using HPLC and the results showed that ferulic, sinapic, ascorbic, salicylic and coumaric acids were the highest in the extract. Biological experiments were performed on male albino adult rats (40 animals, 10 rats for each group), divided into four groups. After five weeks, kidney functions and protein fractions were assessed. In addition, superoxide dismutase (SOD), glutathione (GSH) and malondialdehyde (MDA) enzyme activities were determined in all groups. The results found that kidney function, total protein, albumin and globulin were affected by renal dysfunction and renal fibrosis in the positive control (PC), whereas groups 3 and 4 noted an improvement in renal function nearly or equal to the healthy rats which were fed on a basal diet. Furthermore, the PC group showed significantly decreased levels of enzymatic antioxidants, namely SOD and GSH with a concomitant elevated MDA level compared with those in the negative rats fed on a basal diet. Groups 3 and 4 also reported improvements in enzyme activity. These results were further supported by histopathological findings which revealed a curative effect in groups 3 and 4, which avoided renal dysfunction and renal fibrosis from ethanol-induced toxicity. From the results, it can be said that the black rice extract with the highest amounts of antioxidants led to improvements in all parameters, especially kidney function, total protein, albumin, and globulin, in addition to enzyme activity. Therefore, black rice can be recommended as a benefit to general health.

Dysfunctional Glymphatic System with Disrupted Aquaporin 4 Expression Pattern on Astrocytes Causes Bacterial Product Accumulation in the CSF during Pneumococcal Meningitis.

Pneumococcal meningitis, inflammation of the meninges due to an infection of the Central Nervous System caused by Streptococcus pneumoniae (the pneumococcus), is the most common form of community-acquired bacterial meningitis globally. Aquaporin 4 (AQP4) water channels on astrocytic end feet regulate the solute transport of the glymphatic system, facilitating the exchange of compounds between the brain parenchyma and the cerebrospinal fluid (CSF), which is important for the clearance of waste away from the brain. Wistar rats, subjected to either pneumococcal meningitis or artificial CSF (sham control), received Evans blue-albumin (EBA) intracisternally. Overall, the meningitis group presented a significant impairment of the glymphatic system by retaining the EBA in the CSF compartments compared to the uninfected sham group. Our results clearly showed that during pneumococcal meningitis, the glymphatic system does not function because of a detachment of the astrocytic end feet from the blood-brain barrier (BBB) vascular endothelium, which leads to misplacement of AQP4 with the consequent loss of the AQP4 water channel's functionality. IMPORTANCE The lack of solute drainage due to a dysfunctional glymphatic system leads to an increase of the neurotoxic bacterial material in the CSF compartments of the brain, ultimately leading to brain-wide neuroinflammation and neuronal damage with consequent impairment of neurological functions. The loss of function of the glymphatic system can therefore be a leading cause of the neurological sequelae developing post-bacterial meningitis.

Ameliorative potential role of Rosmarinus officinalis extract on toxicity induced by etoposide in male albino rats.

The present work was showed to assess the effect of administration of rosemary extract on etoposide-induced toxicity, injury and proliferation in male rats were investigated. Forty male albino rats were arranged into four equal groups. 1st group, control; 2nd group, etoposide; 3rd group, co-treated rosemary & etoposide; 4th group, rosemary alone. In comparison to the control group, etoposide administration resulted in a significant increase in serum ALT, AST, ALP, total bilirubin, total protein, and gamma GT. In contrast; a significant decrease in albumin level in etoposide group as compared to G1. G3 revealed a significant decrease in AST, ALT, ALP, total protein and total bilirubin levels and a significant rise in albumin level when compared with G2. Serum levels of urea, creatinine, potassium ions, and chloride ions significantly increased; while sodium ions were significantly decreased in G2 when compared with G1. Also, there was an increase of MDA level for etoposide treated group with corresponding control rats. However, there was a remarkable significant decrease in SOD, GPX and CAT levels in G2 as compared to G1. There was a significant increase in serum hydrogen peroxide (H2O2) and Nitric oxide (NO) levels in group treated with etoposide when compared to control group. It was noticeable that administrated by rosemary alone either with etoposide had not any effect on the levels of H2O2 and Nitric oxide. Serum level of T3 and T4 was significantly increased in etoposide-administered rats in comparison with G1. The administration of rosemary, either alone or with etoposide, increased the serum levels of T3 and T4 significantly when compared to control rats. The gene expression analysis showed significant downregulation of hepatic SOD and GPx in (G2) when compared with (G1). The treatment with rosemary extract produced significant upregulation of the antioxidant enzymes mRNA SOD and GPx. MDA gene was increased in (G2) when contrasted with (G1). Treatment of the etoposide- induced rats with rosemary extract delivered significant decrease in MDA gene expression when compared with etoposide group. Rats treated with etoposide showed significant decline in hepatic Nrf2 protein expression, when compared with G1. While, supplementation of Etoposide- administered rats with the rosemary produced a significant elevation in hepatic Nrf2 protein levels. Additionally, the liver histological structure displayed noticeable degeneration and cellular infiltration in liver cells. It is possible to infer that rosemary has a potential role and that it should be researched as a natural component for etoposide-induced toxicity protection.

SARS-CoV-2 spike protein inhibits megalin-mediated albumin endocytosis in proximal tubule epithelial cells.

Patients with COVID-19 have high prevalence of albuminuria which is used as a marker of progression of renal disease and is associated with severe COVID-19. We hypothesized that SARS-CoV-2 spike protein (S protein) could modulate albumin handling in proximal tubule epithelial cells (PTECs) and, consequently contribute to the albuminuria observed in patients with COVID-19. In this context, the possible effect of S protein on albumin endocytosis in PTECs was investigated. Two PTEC lines were used: HEK-293A and LLC-PK1. Incubation of both cell types with S protein for 16 h inhibited albumin uptake at the same magnitude. This effect was associated with canonical megalin-mediated albumin endocytosis because: (1) DQ-albumin uptake, a marker of the lysosomal degradation pathway, was reduced at a similar level compared with fluorescein isothiocyanate (FITC)-albumin uptake; (2) dextran-FITC uptake, a marker of fluid-phase endocytosis, was not changed; (3) cell viability and proliferation were not changed. The inhibitory effect of S protein on albumin uptake was only observed when it was added at the luminal membrane, and it did not involve the ACE2/Ang II/AT1R axis. Although both cells uptake S protein, it does not seem to be required for modulation of albumin endocytosis. The mechanism underlying the inhibition of albumin uptake by S protein encompasses a decrease in megalin expression without changes in megalin trafficking and stability. These results reveal a possible mechanism to explain the albuminuria observed in patients with COVID-19.

The Interplay between Uremic Toxins and Albumin, Membrane Transporters and Drug Interaction.

Uremic toxins are a heterogeneous group of molecules that accumulate in the body due to the progression of chronic kidney disease (CKD). These toxins are associated with kidney dysfunction and the development of comorbidities in patients with CKD, being only partially eliminated by dialysis therapies. Importantly, drugs used in clinical treatments may affect the levels of uremic toxins, their tissue disposition, and even their elimination through the interaction of both with proteins such as albumin and cell membrane transporters. In this context, protein-bound uremic toxins (PBUTs) are highlighted for their high affinity for albumin, the most abundant serum protein with multiple binding sites and an ability to interact with drugs. Membrane transporters mediate the cellular influx and efflux of various uremic toxins, which may also compete with drugs as substrates, and both may alter transporter activity or expression. Therefore, this review explores the interaction mechanisms between uremic toxins and albumin, as well as membrane transporters, considering their potential relationship with drugs used in clinical practice.

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.

Enhanced blood coagulation and antibacterial activities of carboxymethyl-kappa-carrageenan-containing nanofibers.

Ideal wound dressings should be biocompatible, exhibit high antibacterial activity, and promote blood coagulation. To impart these imperative functions, carboxymethyl-kappa-carrageenan was incorporated into poly(vinyl alcohol) nanofibers (PVA-CMKC). The antibacterial activity of the nanofibers was evaluated. Adsorption of two important blood proteins, fibrinogen and albumin, was also assessed. The adhesion and activation of platelets, and the clotting of whole blood were evaluated to characterize the ability of the nanofibers to promote hemostasis. Adhesion and morphology of both Staphylococcus aureus and Pseudomonas aeruginosa were evaluated using fluorescence microscopy and scanning electron microscopy. CMKC-containing nanofibers demonstrated significant increases in platelet adhesion and activation, percentage of coagulation in whole blood clotting test and fibrinogen adsorption, compared to PVA nanofibers, showing blood coagulation activity. Incorporating CMKC also reduces adhesion and viability of S. aureus and P. aeruginosa bacteria after 24 h of incubation. PVA-CMKC nanofibers show potential application as dressings for wound healing applications.

Surface megalin expression is a target to the inhibitory effect of bradykinin on the renal albumin endocytosis.

Megalin-mediated albumin endocytosis plays a critical role in albumin reabsorption in proximal tubule (PT) epithelial cells (PTECs). Some studies have pointed out the modulatory effect of bradykinin (BK) on urinary protein excretion, but its role in PT protein endocytosis has not yet been determined. Here, we studied the possible correlation between BK and albumin endocytosis in PT. Using LLC-PK1 cells, a model of PTECs, we showed that BK specifically inhibited megalin-mediated albumin endocytosis. This inhibitory effect of BK was mediated by B2 receptor (B2R) because it was abolished by HOE140, an antagonist of B2R, but it was not affected by Lys-des-Arg9-BK, an antagonist of B1. BK induced the stall of megalin in EEA1+ endosomes, but not in LAMP1+ lysosomes, leading to a decrease in surface megalin expression. In addition, we showed that BK, through B2R, activated calphostin C-sensitive protein kinase C, which mediated its effect on the surface megalin expression and albumin endocytosis. These results reveal an important modulatory mechanism of PT albumin endocytosis by BK, which opens new possibilities to understanding the effect of BK on urinary albumin excretion.

Cylindrospermopsin impairs tubular transport function in kidney cells LLC-PK1.

Cylindrospermopsin (CYN) has been involved in cases of poisoning in humans following ingestion. Studies have demonstrated that the kidney is the most affected organ. CYN exposure leads to low-molecular-weight proteinuria and increased excretions of the tubular enzymes in mice, suggesting the damage caused by CYN is mainly tubular. However, the mechanism involved in CYN nephrotoxicity remains unknown. Thus, in order to evaluate the effects of CYN exposure (0.1, 0.5 and 1.0 µg/mL) on tubular renal cells LLC-PK1 distinct mechanisms were analyzed by assessing cell death using flow cytometry, albumin uptake by fluorescence analysis, Na+/K+-ATPase activity by a colorimetric method, RT-qPCR of genes related to tubular transport and function as well as internalization of CYN by ELISA. In this study, CYN was found to induce necrosis in all concentrations. CYN also decreased albumin uptake as well as downregulated megalin and dab2 expression, both proteins involved in albumin endocytosis process. Moreover, CYN appears to be internalized by renal tubular cells through a receptor-mediated endocytosis. Finally, the present study demonstrates that CYN is responsible for disrupting tubular cell transport and function in LLC-PK1 cells.

Hepatotoxic Effect of Lafoensia pacari A. St. Hil. (Lythraceae) on a Diet-Induced Obese Mice Model.

BACKGROUND: Brazilian flora is rich in plants with medicinal properties, which though popular, has contributed to the development of a range of phytotherapic products that use plants to treat and cure diseases. However, studies that use Brazilian plants in the treatment of metabolic disorders are still scarce in the literature. OBJECTIVE: The aim of this study was to analyze the effect of hepatotoxicity Lafoensia pacari on the metabolism of mice with obesity induced by a high-fat diet and to verify the phytochemical difference between the Lafoensia pacari bark of the trunk, leaves, and branches. METHODS: The plant material was collected from April to May in the municipality of Bonito de Minas, MG, Brazil. Qualitative tests for the presence of secondary metabolite classes were performed for leaves, branches and bark of the trunk. Through histological analysis, we evaluated hepatocytes and cell lesions in the liver. RESULTS: The comparative phytochemical analysis of the plant did not reveal alterations between the different plant parts. The phytochemical test showed that is preferable to use the leaves to make the extract to be applied, aiming to reduce the plant aggression. After treatment, greater changes were observed in the animals that received the high-fat diet and the hydroethanolic extract; the levels of AST, ALT, albumin and creatinine that were increased, thus demonstrating a possible toxicity. There were no significant differences in body weight. In the histological analysis, the animals without plant treatment displayed decreased liver weight and reduction in the inflammatory infiltrate. CONCLUSION: We conclude that Lafoensia pacari should be better evaluated for oral consumption and may cause liver damage.

Giardia intestinalis can interact, change its shape and internalize large particles and microorganisms.

Giardia intestinalis is a parasitic protozoan that inhabits its vertebrate hosts' upper small intestine and is the most common cause of waterborne diarrhoea worldwide. Giardia trophozoites present few organelles, and among them, they possess peripheral vesicles (PVs), which are considered an endosomal-lysosomal system. All experimental procedures carried out until now indicate that Giardia ingests macromolecules by fluid-phase and receptor-mediated endocytic pathways. Still, there is no description concerning the interaction and ingestion of large materials. Here, we tested Giardia's capacity to interact with large particles; once, in vivo, it inhabits an environment with a microbiota. We tested protozoan interaction with yeasts, bacteria, latex beads, ferritin and albumin, in different times of interaction and used several microscopy techniques (light microscopy, scanning electron microscopy and transmission electron microscopy) to follow their fate. Giardia interacted with all of the materials we tested. Projections of the plasma membrane similar to pseudopods were seen. As albumin, small markers were found in the PVs while the larger materials were not seen there. Large vacuoles containing large latex beads were detected intracellularly. Thus, we observed that: (1) Giardia interacts with large materials; (2) Giardia can display an amoeboid shape and exhibit membrane projections when in contact with microorganisms and large inorganic materials; (3) the region of the exit of the ventral flagella is very active when in contact with large materials, although all cell surface also present activity in the interactions; (4) intracellular vacuoles, which are not the PVs, present ingested large beads.

Impact of albumin carbamylation on immunoturbidimetric measurement of urinary albumin.

Urinary albumin is one of the main markers used in clinical practice to assess kidney damage. It is usually measured in laboratories through immunological assays, but these assays may not detect molecules with conformational changes, such as carbamylated albumin/proteins. Therefore, this study aimed to investigate the impact of albumin carbamylation on the measurement of albuminuria by an immunoturbidimetric assay. The addition of the carbamylating agent to PBS buffer and urine pool promoted a lower quantification of albumin measured by the immunoturbidimetric method, indicating that this process may be responsible for an underestimation of the results in clinical practice.