Macrophage Infiltration In Kidney Research Articles

Correlation of Urinary Soluble CD163 Levels With Disease Activity and Treatment Response in IgA Nephropathy

BackgroundThe TESTING trial demonstrated that corticosteroids reduce the risk of kidney failure in IgA nephropathy (IgAN) patients but increase the risk of serious adverse events. Reliable noninvasive biomarkers are needed to identify patients who would benefit most from corticosteroid therapy. Previous studies suggest glomerular macrophage infiltration is associated with the response to immunosuppressive therapy in IgAN and urinary soluble CD163(u-sCD163, a marker of M2c macrophage) is correlated with clinical remission in vasculitis. This study aims to investigate the association between u-sCD163 and response of steroids therapy in IgAN. MethodsWe measured u-sCD163 in patients from a large IgAN cohort including China participants of the TESTING trial. The correlation of baseline or serial u-sCD163 and their response of corticosteroids therapy or kidney outcomes were investigated. ResultsIn cross-sectional analysis, u-sCD163 levels correlated with kidney macrophage infiltration, especially in crescentic areas, and with active lesions. Subgroup analysis of the TESTING cohort showed higher levels u-sCD163 were associated with greater benefits from corticosteroids therapy in proteinuria remission [OR, 35.56 (95% CI, 7.62-292.34) vs 3.94 (95% CI, 1.39-12.93), p for interaction 0.036]. Corticosteroids therapy significantly reduced u-sCD163 levels at 6th month compared to placebo group [79% (IQR 58%,91%) vs 37% (-11%,58%), P<0.001]. There was no difference in the suppressive effects on u-sCD163 by either dosage of corticosteroids (full and reduced-dose). The suppression of u-sCD163 was significantly associated with a reduced risk of kidney progression events (adjusted HR 0.52,95% CI 0.30 to 0.93, P=0.027). ConclusionsU-sCD163 is a reliable noninvasive biomarker associated with active pathological lesions in IgAN and can guide glucocorticoid therapy.

Urinary SPP1 has potential as a non-invasive diagnostic marker for focal segmental glomerulosclerosis.

Focal segmental glomerulosclerosis (FSGS) is a type of chronic glomerular nephropathy showing characteristic glomerular sclerosis, diagnosed by kidney biopsy. However, it is difficult and expensive to monitor disease progression with repeated renal biopsy in clinical practice, and thus here we explored the feasibility of urine biomarkers as non-invasive diagnostic tools. We downloaded scRNA-seq datasets of 20 urine cell samples and 3 kidney tissues and obtained two gene lists encoding extracellular proteins for bioinformatic analysis; in addition, we identified key EP-Genes by immunohistochemical staining and performed bulk RNA sequencing with 12 urine samples. We report that urine cells and kidney cells were correlated. A total of 64 EP-Genes were acquired by intersecting genes of distal tubular cluster with extracellular proteins. Function enrichment analysis showed that EP-Genes might be involved in the immune response and extracellular components. Six key EP-Genes were identified and correlated with renal function. IMC showed that key EP-Genes were located mainly in tubules. Cross verification and examination of a urine RNAseq dataset showed that SPP1 had diagnostic potential for FSGS. The presence of urine SPP1 was primarily associated with macrophage infiltration in kidney, and the pathogenesis of FSGS may be related to innate immunity. Urinary cells seemed to be strongly similar to kidney cells. In summary, SPP1 levels reflect renal function and may have potential as a biomarker for non-invasive diagnosis of FSGS.

MO285: FOSL1 Preserves Klotho Expression and Limits Acute Kidney Injury

Abstract BACKGROUND AND AIMS Fosl1 (FRA1, Fos-related-antigen 1) is a transcription factor of the AP-1 complex (activator protein 1) that regulates the expression of genes that regulates processes involved in acute kidney injury (AKI) such differentiation, inflammation, proliferation and cell death. We have now explored the role of Fosl1 in AKI and repair. METHOD The function of Fosl1 was explored in murine nephrotoxic AKI induced by folic acid or cisplatin in wild type and genetically modified mice tubular cell Fosl1 deficient mice (Fosl1Δtub). RT-qPCR, western blot, and immunohistochemistry were used to assess gene and protein expression. Direct regulation of Klotho by Fosl1 was explored by chromatin immunoprecipitation (ChIP). Murine tubular cells were cultured in an inflammatory milieu promoted by TWEAK and Fosl1 was targeted by siRNA. RESULTS Fosl1 was one of the most upregulated transcription factors in experimental nephrotoxic AKI transcriptomics and also one the transcription factors binding to the Klotho promoter (Panel A). Fosl1 upregulation was confirmed in experimental nephrotoxic AKI and in human AKI and localized to tubular cell nuclei at early times points (panel B). Fosl1 deficient (Fosl1Δtub) mice developed more severe folic acid- or cisplatin-induced AKI and higher proinflammatory cytokine expression and kidney macrophage infiltration (Panel C). Additionally, kidney expression of the nephroprotective and antiaging factor Klotho was more severely depressed in Fosl1Δtub mice (Panel D). Enrichment of AP1 binding sites was found in the Klotho promoter and we confirmed direct Fosl1 binding to the Klotho promoter in a ChIP assay. Moreover, Fosl1Δtub mice had disturbed expression of cell cycle regulators and PCNA expression, suggesting a dysregulation in kidney repair. In tubular cells cultured in an inflammatory milieu, Fosl1 expression was also upregulated. Fosl1 siRNA targeting in cultured tubular cells increased inflammatory gene expression and cell death and decreased Klotho expression. CONCLUSION Fosl1 contributes to an adaptive kidney response during AKI that limits kidney injury and includes Klotho expression and Fosl1 deficiency promotes an accelerated loss of klotho and more severe AKI.

Dynamics of kidney M1 and M2 macrophages in patients with myocardial infarction

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): The reported study was funded by RFBR. Project number 19-315-60005. Introduction Heart-kidney axis is an active participant of the formation and progression of chronic heart and renal failure in patients with myocardial infarction (MI). Innate immunity play a great role in this collaboration between the heart and kidney according to the experimental data. However, there is not enough data about clinical studies. Purpose to assess the dynamics of kidney CD68+, CD80+, CD206+, CD163+ and stabilin-1+ macrophages in patients with fatal MI. Methods and results: 30 patients with fatal MI type 1 were included. STEMI was in 87% (n = 26), in 53% (n = 16) it was recurrent MI. Chronic kidney disease was diagnosed in 33% (n = 10). They were divided according to the timeline of MI histopathology into 2 groups: early phase – inflammatory and reparative periods (to the 3d day after MI), late phase - regenerative and late periods (from the 3d to the 28 day after MI). Macrophages infiltration was assessed by immunohistochemistry. CD68+ was used, as a biomarker for M1 and M2 macrophages; CD80+, as a biomarker for M1 macrophages; stabilin-1+ and CD163+, CD206+, as only for M2 macrophages. The numbers of kidney CD68+ macrophages did not change significantly during the 28 days after MI: 42.8 ± 8 (early phase), 36.4 ± 13 (late phase). The numbers of kidney stabilin-1+ cells did not change also 2.1 ± 1 (early phase), 2.4 ± 1 (late phase), as CD163+ 59.51 ± 6 (early phase), 65.9 ± 25 (late phase). However, the numbers of CD206+ cells (M2 macrophages) increased from the early to the late phase: from 2 ± 1 to 8.5 ± 1 (p = 0.0001). The numbers of CD80+ cells (M1 macrophages) decreased from the early to the late phase from 4.2 ± 1 to 2 ± 1 (p = 0.02). Conclusions The number of kidney CD68+, CD163+ and stabilin-1+ macrophages did not show significantly dynamics during the first 28 days after myocardial infarction. We have noted the increase of CD206+ macrophage infiltration in kidney from the early phase after myocardial infarction to the late phase. Dynamics of CD80+ cells was the opposite; they decreased to the late phase after myocardial infarction.

Effects of autophagy on macrophage adhesion and migration in diabetic nephropathy

Objective: Macrophage infiltration in kidney is a major pathological feature of diabetic nephropathy (DN), which has been demonstrated associate with macrophages autophagy homeostasis. However, the relationships between autophagy and the infiltration response related of macrophages adhesion and migration are unknown. This study aims to investigate the impact of macrophages adhesion and migration by modulating autophagy.Methods: In vivo, rats were randomly distributed into control (NC) and DN groups. The pathological changes in renal tissue were assessed, and expression of CD68, LC3, P62 were analyzed. In vitro, RAW264.7 cells were divided into NC and high glucose (HG) groups. The capacity of macrophages adhesion migration and the expression of autophagy markers were observed with and without autophagy modulators (rapamycin, 3-methyladenine, chloroquine, and bafilomycin A1 for RAPA, 3-MA, CQ, BAFA). The macrophages autophagosome and the process of degradation and fusion of autophagosome-lysosome were observed by electron microscopy.Results: In vivo, renal injury is aggravated in diabetic rat compared with NC group. The autophagy level is inhibited in renal tissues of DN group with the increasing expression of CD68 and P62, while expression level of LC3 decreased (p < .05). In vitro, HG and 3-MA reduce the numbers of autophagosome of macrophages to inhibit autophagy level with decrease expression of LC3 and Beclin-1, but increase expression of P62, which promote the adhesion and migration capacity of macrophages (p < .05). Moreover, CQ and BAFA suppress autophagy level by inhibiting the process of autophagosome-lysosome degradation and fusion of macrophages, as well as the expression of LC3 and Beclin-1. We notice an increase expression of P62 by CQ and BAFA stimulation (p < .05). CQ and BAFA further facilitate the adhesion and migration capacity of macrophages. However, RAPA increases the numbers of macrophages autophagosome that inhibited by HG, resulting in a recovery of autophagy level with increase expression of LC3 and Beclin-1, whereas a reduction expression of P62, which lead to inhibition of adhesion and migration of macrophages induced by HG (p < .05)Conclusions: High glucose efficiently reduced the level of macrophage autophagy, following macrophages adhesion and migration enhanced when autophagy is suppressed. Activation of autophagosome improve the level of autophagy, but leading to a reduction of the macrophages adhesion and migration. While, inhibiting the process of degradation and fusion of autophagosome-lysosome suppress the level of autophagy and promote the macrophages adhesion and migration. These results indicate that high glucose may play an important role in macrophages adhesion and migration through modulating autophagy activities in diabetic nephropathy.

Fatty acid receptor modulator PBI-4050 inhibits kidney fibrosis and improves glycemic control.

Extensive kidney fibrosis occurs in several types of chronic kidney diseases. PBI-4050, a potentially novel first-in-class orally active low-molecular weight compound, has antifibrotic and antiinflammatory properties. We examined whether PBI-4050 affected the progression of diabetic nephropathy (DN) in a mouse model of accelerated type 2 diabetes and in a model of selective tubulointerstitial fibrosis. eNOS-/- db/db mice were treated with PBI-4050 from 8-20 weeks of age (early treatment) or from 16-24 weeks of age (late treatment). PBI-4050 treatment ameliorated the fasting hyperglycemia and abnormal glucose tolerance tests seen in vehicle-treated mice. In addition, PBI-4050 preserved (early treatment) or restored (late treatment) blood insulin levels and increased autophagy in islets. PBI-4050 treatment led to significant improvements in lifespan in the diabetic mice. Both early and late PBI-4050 treatment protected against progression of DN, as indicated by reduced histological glomerular injury and albuminuria, slow decline of glomerular filtration rate, and loss of podocytes. PBI-4050 inhibited kidney macrophage infiltration, oxidative stress, and TGF-β-mediated fibrotic signaling pathways, and it also protected against the development of tubulointerstitial fibrosis. To confirm a direct antiinflammatory/antifibrotic effect in the kidney, further studies with a nondiabetic model of EGFR-mediated proximal tubule activation confirmed that PBI-4050 dramatically decreased the development of the associated tubulointerstitial injury and macrophage infiltration. These studies suggest that PBI-4050 attenuates development of DN in type 2 diabetes through improvement of glycemic control and inhibition of renal TGF-β-mediated fibrotic pathways, in association with decreases in macrophage infiltration and oxidative stress.

Arginase inhibition: a new treatment for preventing progression of established diabetic nephropathy

Our previous publication showed that inhibition of arginase prevents the development of diabetic nephropathy (DN). However, identification of targets that retard the progression of established DN-which is more clinically relevant-is lacking. Therefore, we tested the hypothesis that arginase inhibition would prevent the progression of established DN. Effects of arginase inhibition were compared with treatment with the angiotensin-converting enzyme inhibitor captopril, a current standard of care in DN. Experiments were conducted in Ins2(Akita) mice treated with the arginase inhibitor S-(2-boronoethyl)-l-cysteine (BEC) or captopril starting at 6 wk of age for 12 wk (early treatment) or starting at 12 wk of age for 6 wk (late treatment). Early and late treatment with BEC resulted in protection from DN as indicated by reduced albuminuria, histological changes, kidney macrophage infiltration, urinary thiobarbituric acid-reactive substances, and restored nephrin expression, kidney nitrate/nitrite, kidney endothelial nitric oxide synthase phosphorylation, and renal medullary blood flow compared with vehicle-treated Ins2(Akita) mice at 18 wk of age. Interestingly, early treatment with captopril reduced albuminuria, histological changes, and kidney macrophage infiltration without affecting the other parameters, but late treatment with captopril was ineffective. These findings highlight the importance of arginase inhibition as a new potential therapeutic intervention in both early and late stages of diabetic renal injury.

Epoxyeicosatrienoic acid analog attenuates angiotensin II hypertension and kidney injury.

Epoxyeicosatrienoic acids (EETs) contribute to blood pressure regulation leading to the concept that EETs can be therapeutically targeted for hypertension and the associated end organ damage. In the present study, we investigated anti-hypertensive and kidney protective actions of an EET analog, EET-B in angiotensin II (ANG II)-induced hypertension. EET-B was administered in drinking water for 14 days (10 mg/kg/d) and resulted in a decreased blood pressure elevation in ANG II hypertension. At the end of the two-week period, blood pressure was 30 mmHg lower in EET analog-treated ANG II hypertensive rats. The vasodilation of mesenteric resistance arteries to acetylcholine was impaired in ANG II hypertension; however, it was improved with EET-B treatment. Further, EET-B protected the kidney in ANG II hypertension as evidenced by a marked 90% decrease in albuminuria and 54% decrease in nephrinuria. Kidney histology demonstrated a decrease in renal tubular cast formation in EET analog-treated hypertensive rats. In ANG II hypertension, EET-B treatment markedly lowered renal inflammation. Urinary monocyte chemoattractant protein-1 excretion was decreased by 55% and kidney macrophage infiltration was reduced by 52% with EET-B treatment. Overall, our results demonstrate that EET-B has anti-hypertensive properties, improves vascular function, and decreases renal inflammation and injury in ANG II hypertension.

Hyperlipidemia-Associated Renal Damage Decreases Klotho Expression in Kidneys from ApoE Knockout Mice

BackgroundKlotho is a renal protein with anti-aging properties that is downregulated in conditions related to kidney injury. Hyperlipidemia accelerates the progression of renal damage, but the mechanisms of the deleterious effects of hyperlipidemia remain unclear.MethodsWe evaluated whether hyperlipidemia modulates Klotho expression in kidneys from C57BL/6 and hyperlipidemic apolipoprotein E knockout (ApoE KO) mice fed with a normal chow diet (ND) or a Western-type high cholesterol-fat diet (HC) for 5 to 10 weeks, respectively.ResultsIn ApoE KO mice, the HC diet increased serum and renal cholesterol levels, kidney injury severity, kidney macrophage infiltration and inflammatory chemokine expression. A significant reduction in Klotho mRNA and protein expression was observed in kidneys from hypercholesteromic ApoE KO mice fed a HC diet as compared with controls, both at 5 and 10 weeks. In order to study the mechanism involved in Klotho down-regulation, murine tubular epithelial cells were treated with ox-LDL. Oxidized-LDL were effectively uptaken by tubular cells and decreased both Klotho mRNA and protein expression in a time- and dose-dependent manner in these cells. Finally, NF-κB and ERK inhibitors prevented ox-LDL-induced Klotho downregulation.ConclusionOur results suggest that hyperlipidemia-associated kidney injury decreases renal expression of Klotho. Therefore, Klotho could be a key element explaining the relationship between hyperlipidemia and aging with renal disease.

Thrombospondin 1 mediates renal dysfunction in a mouse model of high-fat diet-induced obesity

Obesity is prevalent worldwide and is a major risk factor for many diseases including renal complications. Thrombospondin 1 (TSP1), a multifunctional extracellular matrix protein, plays an important role in diabetic kidney diseases. However, whether TSP1 plays a role in obesity-related kidney disease is unknown. In the present studies, the role of TSP1 in obesity-induced renal dysfunction was determined by using a diet-induced obese mouse model. The results demonstrated that TSP1 was significantly upregulated in the kidney from obese mice. The increased TSP1 was localized in the glomerular mesangium as well as in the tubular system from obese wild-type mice. Obese wild-type mice developed renal hypertrophy and albuminuria, which was associated with increased kidney macrophage infiltration, augmented kidney inflammation, and activated transforming growth factor (TGF)-β signaling and renal fibrosis. In contrast, obese TSP1-deficient mice did not develop these kidney damages. Furthermore, in vitro studies demonstrated that leptin treatment stimulated the expression of TSP1, TGF-β1, fibronectin, and collagen type IV in mesangial cells isolated from wild-type mice. These leptin-stimulated effects were abolished in TSP1-deficient mesangial cells. Taken together, these data suggest that TSP1 is an important mediator for obesity- or hyperleptinemia-induced kidney dysfunction.

Angiotensin type 1 receptor modulates macrophage polarization and renal injury in obesity

The mechanisms for increased risk of chronic kidney disease (CKD) in obesity remain unclear. The renin-angiotensin system is implicated in the pathogenesis of both adiposity and CKD. We investigated whether the angiotensin type 1 (AT(1)) receptor, composed of dominant AT(1a) and less expressed AT(1b) in wild-type (WT) mice, modulates development and progression of kidney injury in a high-fat diet (HFD)-induced obesity model. WT mice had increased body weight, body fat, and insulin levels and decreased adiponectin levels after 24 wk of a high-fat diet. Identically fed AT(1a) knockout (AT1aKO) mice gained weight similarly to WT mice, but had lower body fat and higher plasma cholesterol. Both obese AT1aKO and obese WT mice had increased visceral fat and kidney macrophage infiltration, with more proinflammatory M1 macrophage markers as well as increased mesangial expansion and tubular vacuolization, compared with lean mice. These abnormalities were heightened in the obese AT1aKO mice, with downregulated M2 macrophage markers and increased macrophage AT(1b) receptor. Treatment with an AT(1) receptor blocker, which affects both AT(1a) and AT(1b), abolished renal macrophage infiltration with inhibition of renal M1 and upregulation of M2 macrophage markers in obese WT mice. Our data suggest obesity accelerates kidney injury, linked to augmented inflammation in adipose and kidney tissues and a proinflammatory shift in macrophage and M1/M2 balance.

Mizoribine reduces renal injury and macrophage infiltration in non-insulin-dependent diabetic rats

Macrophage infiltration in kidney is one of the most important events for the progression of diabetic nephropathy. Mycophenolate mofetil (MMF), an anti-inflammatory agent, has been shown to suppress macrophage infiltration and to improve renal injury in streptozotocin-induced diabetic kidneys. We examined whether mizoribine, which acts through immunosuppressive mechanisms similar to MMF, inhibits progression of diabetic nephropathy in non-insulin-dependent diabetic rats. Male Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a non-insulin-dependent diabetic model, and Long-Evans Tokushima Otsuka (LETO) rats, a non-diabetic control, were studied at 35 weeks of age. OLETF rats were randomized to receive mizoribine (5 or 10 mg/kg) or normal saline for 8 weeks. Histological changes such as glomerulosclerosis and interstitial fibrosis and the number of ED1- and CD5-positive cells in the kidney were assessed. By using reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry, monocyte chemoattractant protein-1 (MCP-1), osteopontin (OPN) and transforming growth factor (TGF)-beta1 expression in the kidney was also analysed. Urinary albumin excretion in OLETF rats increased compared with that in LETO rats. Administration of mizoribine suppressed urinary albumin excretion. Development of glomerulosclerosis, interstitial fibrosis and macrophage infiltration in the kidney was also inhibited by treatment with mizoribine. The expression of MCP-1, OPN and TGF-beta1 mRNA in untreated OLETF rats was significantly increased compared with that in LETO rats. By immunohistochemistry, increased expression of MCP-1, OPN and TGF-beta1 was found in the tubules and glomeruli of untreated OLETF rats. This expression was significantly suppressed by treatment with mizoribine. Mizoribine inhibited renal macrophage accumulation and prevented the progression of glomerulosclerosis and interstitial fibrosis in non-insulin-dependent diabetic kidneys. In addition to standard treatments, anti-inflammatory agents may be useful for management of non-insulin-dependent diabetic nephropathy.