Growth arrest-specific protein 6 as a marker of nephritis in systemic sclerosis and juvenile systemic lupus erythematosus patients.

Background: Renal impairments commonly occur as a complication of autoimmune connective tissue diseases (CTDs). Therefore, early nephritis prediction is vital for patient outcomes. Growth Arrest-Specific Protein 6 (GAS6) was found to be upregulated in many types of inflammatory renal disease, including diabetic nephropathy.Aim: To evaluate GAS6 as a predictor of renal impairment in adults with systemic sclerosis (SSc) and children with systemic lupus Erythematosus (SLE).Methods: The study included 60 patients with SSc and 40 children with SLE. The serum level of GAS6 was measured using the ELISA technique. In adults with SSc, total proteins in 24-h urine concentration of >300 mg/24 h indicated renal inflammation, while in children with SLE, nephritis was diagnosed by abnormal renal pathology.Results: In SSc patients, GAS6 significantly increased in patients with proteinuria. GAS6 is an independent predictor of nephritis with an odds ratio (OR) of 1.06 and a 95% confidence interval (CI) of 1.0-1.1. at cutoff 12.2 ng/mL GAS6 predicted proteinuria with sensitivity 86.7% (95% CI: 59.5% to 98.3%), specificity 57.8% (95% CI: 42.1% to 72.3%), positive predictive value 40.6% (95% CI: 31.5% to 50.4%), negative predictive value 92.9% (95% CI: 77.7% to 97.73%), and accuracy 65.0% (95% CI: 51.6% to 76.9%). In SLE patients, Serum GAS6 did not differ significantly between children with and without lupus nephritis.Conclusion: GAS6 is an independent predictor of nephritis in patients with SSc. However, there is no association between GAS6 and nephritis in juvenile patients with SLE.

Increased cytokines/chemokines and hyponatremia as a possible cause of clinically mild encephalitis/encephalopathy with a reversible splenial lesion associated with acute focal bacterial nephritis.

OBJECTIVE: Clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS), the second most common encephalopathy syndrome in Japan, is most often associated with viral infection. Bacterial MERS has been rarely reported but is mostly associated with acute focal bacterial nephritis (AFBN) for an unknown reason. We examined cytokines and chemokines in four MERS patients with AFBN to determine if they play an important role in the pathogenesis. METHODS: We examined the clinical charts and MRI results in four MERS patients with AFBN, and measured 10 cytokines and chemokines in serum and cerebrospinal fluid in the acute phase. These were analyzed using the Mann-Whitney U test, compared with the control group (cases with a non-inflammatory neurological disease). Longitudinal changes in the serum cytokine and chemokine levels were evaluated in two patients. RESULTS: Hyponatremia was observed in all four patients with MERS associated with AFBN (128-134 mEq/L). CSF analysis revealed increased cytokines/chemokines associated with Th1 (CXCL10, TNF-α, IFN-γ), T reg (IL-10), Th17 (IL-6), and neutrophil (IL-8 and CXCL1). In serum, upregulation was observed in those associated with Th1 (CXCL10, TNF-α, IFN-γ), Th17 (IL-6), and inflammasome (IL-1ß). The increased serum cytokines/chemokines in the acute stage normalized within 2 weeks in patients 1 and 2, so examined, in accordance with their clinical improvement. CONCLUSION: Increased cytokines/chemokines and hyponatremia may be factors that explain why AFBN is likely to cause MERS.

Serum levels of galactose-deficient IgA1 in Chinese children with IgA nephropathy, IgA vasculitis with nephritis, and IgA vasculitis.

OBJECTIVE: IgA nephropathy (IgAN) and IgA vasculitis with nephritis (IgAV-N) are related diseases. Galactose-deficient IgA1 (Gd-IgA1) plays an important role in the pathology of IgAV-N and IgAN, so we aim to compare the serum levels of Gd-IgA1 in Chinese pediatric patients with IgAN, IgAV-N, and IgAV. METHODS: We retrospectively enrolled 52 patients with IgAN, 57 patients with IgAV-N, 26 patients with IgAV, and 40 healthy children. The serum levels of Gd-IgA1 were measured at the time of biopsy using a lectin-based ELISA method. RESULTS: Gd-IgA1 levels in IgAV-N patients and IgAN patients were higher than in healthy controls (303.94 ± 39.37 U/ml, 314.91 ± 47.79 U/ml vs. 273.57 ± 48.29 U/ml, P < 0.001), and Gd-IgA1 levels in IgAV-N patients were higher than in IgAV patients (303.94 ± 39/ml vs. 286. 21 ± 38.81 U/ml, P = 0.059), but the latter result is not statistically significant. The Gd-IgA1 levels in IgAV patients were comparable with those in healthy controls (286.21 ± 38.81 U/ml vs. 273.57 ± 48.29 U/ml, P = 0.267). Among the four groups, we did not observe significant correlations of Gd-IgA1 levels with eGFR, proteinuria, or the MEST-C score. CONCLUSION: Serum Gd-IgA1 maybe involved in the pathogenesis of the IgAV-N and IgAN. However, we found no statistically significant correlation between Gd-IgA1 levels and clinical and pathological features.

Is adiponectin in children with immunoglobulin A vasculitis a suitable biomarker of nephritis in the course of the disease?

INTRODUCTION: Immunoglobulin A vasculitis (IgAV) is the most common form of vasculitis in children. Nephritis in the course of this disease (IgAVN) is observed in 30-50% of patients and might lead to chronic kidney disease (CKD) and end-stage renal disease (ESRD). Finding a non-invasive biomarker to distinguish initially between patients with and without nephritis and to facilitate a therapeutic decision to reduce the risk of long-term renal impairment is currently the target of much research. The aim of this study was to evaluate the adiponectin concentration in children with IgAV and estimate whether it might be used as a marker of IgAVN. MATERIAL AND METHODS: The study involved 29 IgAV children and 34 healthy controls. Eleven (38%) patients had renal involvement (IgAV-N) and 18 (62%) did not exhibit nephritis (IgAV-noN). The serum adiponectin level was estimated in children in an acute phase of IgAV and after 2-6 months during a follow-up visit. The relationship between the concentration of adiponectin and anthropometric measurements, epidemiological data and laboratory parameters were evaluated. RESULTS: The concentration of adiponectin in serum was significantly higher in children with acute phase of IgAV as compared to the control group (p < 0.001), and in patients without renal involvement in comparison with IgAV-N children (p < 0.049). In analysis of correlation we found a negative relationship between adiponectin level and serum creatinine concentration (r = -0.437, p = 0.02). The logistic regression evaluation demonstrated that a low adiponectin level increased the risk of nephritis in the course of IgAV. CONCLUSIONS: Our study revealed that the serum adiponectin level increased markedly in patients with IgAV. We also documented that higher risk of nephritis in the course of the disease was associated with lower concentration of this hormone.

Serum long noncoding RNAs FAS-AS1 & PVT1 are novel biomarkers for systemic lupus erythematous.

Background: Systemic Lupus Erythematous (SLE) is a chronic systemic autoimmune disorder whose diagnosis depends on combination of multiple factors. Circulating lncRNAs could serve as diagnostic non-invasive biomarkers for SLE. We hypothesised that serum FAS-AS1 and PVT1 are new biomarkers for SLE that relate to clinical features and laboratory markers. Materials and Method: Measurement of serum FAS-AS1 & PVT1 by qRT-PCR, analysis of the association between two RNAs and the clinical data, activity index and laboratory markers by standard routine methods. Results: There was a significant relative increased serum FAS-AS1 (median (IQR) 2.19 (0.13-8.62) and a significant reduced PVT1 (median (IQR) 0.52 (0.01-7.55) in SLE patients compared to controls (P < 0.0001 for FAS-AS1 and = 0.007 for PVT1). Serum FAS-AS1 and PVT1 were positively correlated (r= 0.37, P = 0.001). Higher FAS-AS1 was significantly linked with nephritis (P = 0.011), positive anti-dsDNA (P= 0.01) and lower serum PVT1 was significantly associated with oral ulcers (P= 0.023), photosensitivity (P= 0.017), and neurological manifestations (P= 0.041). Serum PVT1 negatively correlated with age (r= -0.52, P< 0.0001) and ESR level (r= -0.29, P= 0.011) in SLE patients. No correlation between disease activity and serum FAS-AS1 or PVT1 was detected. Conclusions: Our study provides evidence that serum FAS-AS1 and PVT1 are new biomarkers for SLE.

IgA vasculitis with nephritis in children.

Immunoglobulin A vasculitis (IgAV), formerly known as Henoch-Schönlein purpura (HSP), is the most common form of systemic vasculitis in children. Although the first case of IgAV was described more than 200 years ago, its etiology still remains unclear. Nephrological symptoms are observed in 30-50% of children during the course of the disease, and in up to 91% of cases within 6 weeks of the onset of the first symptoms. Whereas other organ manifestations of IgAV are mostly benign and self-limiting, nephritis may lead to chronic kidney disease (CKD) and end-stage renal disease (ESRD). Appropriate treatment commenced early enough can stop the disease progression. However, even in severe cases there are no evidence-based guidelines, which makes the therapeutic decisions more difficult. In this article, which is the most up-to-date overview regarding IgAV, we discuss the disease's pathogenesis, the clinical forms of renal involvement in the course of the disease, the risk factors for adverse prognosis and treatment options in accordance with current recommendations.

Ergosterol ameliorates renal inflammatory responses in mice model of diabetic nephropathy.

Ergosterol (ERG) was reported to exhibit anti-inflammatory and anti-oxidative activities. Besides, ERG was found to attenuate kidney injury in the diabetic mouse. However, the protective effect of ERG in diabetic nephropathy-induced inflammation remains unclear. We aimed to study whether ERG could alleviate diabetic nephropathy-induced inflammation and explore the underlying mechanisms. The diabetic nephropathy mice model was induced by intraperitoneal injection of 30 mg/kg Streptozotocin (STZ). The inflammatory cytokines levels, and insulin concentration in the serum of both diabetic nephropathy patients and mouse model were determined by ELISA. mRNA and protein expression were analyzed by RT-PCR and Western blot, respectively. Fasting blood glucose levels were detected using a commercial kit. Blood biochemistry levels were determined by an automatic analyzer. Mesangium proliferation was detected by PAS staining. It was found that serum levels of IL-6, TNF-α, and MCP-1 dramatically increased in the diabetic nephropathy patients. In mice, ERG treatment greatly decreased fasting blood glucose levels, inflammatory cytokine levels, and renal injury, while it enhanced the insulin level. Mechanically, ERG treatment dramatically decreased NF-κB signaling pathway. Our findings highlight the potential of ERG as an effective agent to treat diabetic nephropathy.

Uric acid and inflammation in kidney disease.

Asymptomatic hyperuricemia is frequently observed in patients with kidney disease. Although a substantial number of epidemiologic studies have suggested that an elevated uric acid level plays a causative role in the development and progression of kidney disease, whether hyperuricemia is simply a result of decreased renal excretion of uric acid or is a contributor to kidney disease remains a matter of debate. Over the last two decades, multiple experimental studies have expanded the knowledge of the biological effects of uric acid beyond its role in gout. In particular, uric acid induces immune system activation and alters the characteristics of resident kidney cells, such as tubular epithelial cells, endothelial cells, and vascular smooth muscle cells, toward a proinflammatory and profibrotic state. These findings have led to an increased awareness of uric acid as a potential and modifiable risk factor in kidney disease. Here, we discuss the effects of uric acid on the immune system and subsequently review the effects of uric acid on the kidneys mainly in the context of inflammation.

Renal Chemerin Expression is Induced in Models of Hypertensive Nephropathy and Glomerulonephritis and Correlates with Markers of Inflammation and Fibrosis.

Chemerin and its receptor, chemokine-like receptor 1 (CmklR1), are associated with chemotaxis, inflammation, and endothelial function, especially in metabolic syndrome, coronary heart disease, and hypertension. In humans, circulating chemerin levels and renal function show an inverse relation. So far, little is known about the potential role of chemerin in hypertensive nephropathy and renal inflammation. Therefore, we determined systemic and renal chemerin levels in 2-kidney-1-clip (2k1c) hypertensive and Thy1.1 nephritic rats, respectively, to explore the correlation between chemerin and markers of renal inflammation and fibrosis. Immunohistochemistry revealed a model-specific induction of chemerin expression at the corresponding site of renal damage (tubular vs. glomerular). In both models, renal expression of chemerin (RT-PCR, Western blot) was increased and correlated positively with markers of inflammation and fibrosis. In contrast, circulating chemerin levels remained unchanged. Taken together, these findings demonstrate that renal chemerin expression is associated with processes of inflammation and fibrosis-related to renal damage. However, its use as circulating biomarker of renal inflammation seems to be limited in our rat models.

Association of Higher Advanced Oxidation Protein Products (AOPPs) Levels in Patients with Diabetic and Hypertensive Nephropathy.

Background and Objectives: Diabetes mellitus (DM) and hypertension (HT) are characterized by cell damage caused by inflammatory and metabolic mechanisms induced by alteration in reduction-oxidative status. Serum advanced oxidation protein products (AOPP) are new markers of protein damage induced by oxidative stress. We evaluated serum levels of AOPP in a cohort of patients with DM and HT, with or without renal complications, compared with a control healthy population. Materials and Methods: The study group comprised of 62 patients with type 2 DM and 56 with HT. The 62 patients affected by DM were further distinguished in 24 subjects without renal impairment, 18 with diabetic nephropathy (DN), 20 with chronic kidney disease (CKD) stage 2-3 secondary to DN. The subgroup of 56 patients with primary HT comprised 26 subjects without renal complications and 30 with CKD (stage 2-3) secondary to HT. Thirty healthy controls, matched for age and sex, were recruited among blood donors. Results: Increased AOPP levels were found in DM patients compared with healthy subjects, although not significantly. This index was higher and more significant in patients with DN and CKD secondary to DN than in DM patients without nephropathy (p < 0.05) or controls (p < 0.0001). Patients with HT and with kidney impairment secondary to HT also had significantly higher AOPP serum levels than controls (p < 0.01 and p < 0.0001, respectively). There were no significant differences in mean AOPP levels among DM and HT patients. Conclusion: Our study showed that oxidative stress was higher in diabetic or hypertensive subjects than in healthy controls and, in particular, it appeared to be more severe in patients with renal complications. We suggest that the assessment of AOPP in diabetic and hypertensive patients may be important to predict the onset of renal failure and to open a new perspective on the adoption of antioxidant molecules to prevent CKD in those settings.

Differences in Serum Amino Acid Phenotypes Among Patients with Diabetic Nephropathy, Hypertensive Nephropathy, and Chronic Nephritis.

BACKGROUND We assessed levels of circulating amino acids in different etiologies of chronic kidney disease (CKD) and the association of amino acids with risk factors of CKD progression. MATERIAL AND METHODS High-performance liquid chromatography-based analysis was used to determine amino acid profiles in patients with diabetic nephropathy (DN, n=20), hypertensive nephropathy (HN, n=26), and chronic nephritis (CN, n=33), and in healthy controls (HC, n=25). RESULTS All 3 types of CKD patients displayed decreased serum levels of serine, glycine, GABA, and tryptophan compared with healthy controls. Moreover, serine and tryptophan were positively correlated with glucose in DN cohorts. Total cholesterol was positively correlated with tryptophan levels in the DN cohort and negatively correlated with serine levels in the CN cohort. In the HN cohort, glycine was negatively correlated with triglyceride levels, and systolic blood pressure (SBP) was negatively correlated with GABA levels. CONCLUSIONS Patients with different etiologies of CKD have significantly different amino acids profiles, and this indicates specific supplementary nutritional needs in CKD patients.

Role of p300 in the pathogenesis of Henoch-Schonlein purpura nephritis and as a new target of glucocorticoid therapy in mice.

BACKGROUND: Henoch-Schonlein purpura nephritis (HSPN) is a very common secondary kidney disease of childhood. Its pathogenesis and the treatment mechanism of glucocorticoid have not been fully elucidated. The aim of this study was to determine the relationship between p300 and the pathogenesis, glucocorticoid therapy in mice with HSPN, respectively. METHODS: Forty-eight C57BL/6N male mice, weighing 18 to 20 g, were selected (3-4 weeks old, n = 8 per group). The mice in the normal control group (Group I) were given normal solvent and the HSPN model group (Group II) were given sensitizing drugs. The mice in Group III were injected intraperitoneally with dexamethasone after being given sensitizing drugs. Meanwhile, mice in Groups IV, V and VI with conditional knockout of p300 were also given normal solvent, sensitizing drugs and dexamethasone.The levels of serum IgA, creatinine, and circulating immune complex (CIC) concentrations, 24 h urinary protein and urinary erythrocyte in C57 wild mice, and p300 conditional knockout mice in each group were measured. The expression of p300 in renal tissues and the expression of glucocorticoid receptor (GR) α and ß, transforming growth factor (TGF)-ß1, and activator protein (AP)-1 after dexamethasone treatment were determined by real-time polymerase chain reaction and Western blotting. RESULTS: Compared with the normal solvent control group (Group I), the expression of p300 mRNA in the model group (Group II) was significantly up-regulated. Western blotting further confirmed the result. Urinary erythrocyte count, 24 h urinary protein quantification, serum IgA, CIC, and renal pathologic score in Group V were distinctly decreased compared with non-knockout mice in Group II (9.7 ±â€Š3.8 per high-power field [/HP] vs. 18.7 ±â€Š6.2/HP, t = 1.828, P = 0.043; 0.18 ±â€Š0.06 g/24 h vs. 0.36 ±â€Š0.08 g/24 h, t = 1.837, P = 0.042; 18.78 ±â€Š0.85 mg/mL vs. 38.46 ±â€Š0.46 mg/mL, t = 1.925, P = 0.038; 0.80 ±â€Š0.27 µg/mL vs. 1.64 ±â€Š0.47 µg/mL, t = 1.892, P = 0.041; 7.0 ±â€Š0.5 vs. 18.0 ±â€Š0.5, t = 1.908, P = 0.039). Compared with non-knockout mice (Group III), the level of urinary erythrocyte count and serum IgA in knockout mice (Group VI) increased significantly after treatment with dexamethasone (3.7 ±â€Š0.6/HP vs. 9.2 ±â€Š3.5/HP, t = 2.186, P = 0.024; 12.38 ±â€Š0.26 mg/mL vs. 27.85 ±â€Š0.65 mg/mL, t = 1.852, P = 0.041). The expression level of GRα was considerably increased in the knockout group after dexamethasone treatment compared with non-knockout mice in mRNA and protein level (t = 2.085, P = 0.026; t = 1.928, P = 0.035), but there was no statistically significant difference in the expression level of GRß between condition knockout and non-knockout mice (t = 0.059, P = 0.087; t = 0.038, P = 1.12). Furthermore, the expression levels of glucocorticoid resistance genes (AP-1 and TGF-ß1) were notably increased after p300 knockout compared with non-knockout mice in mRNA and protein level (TGF-ß1: t = 1.945, P = 0.034; t = 1.902, P = 0.039; AP-1: t = 1.914, P = 0.038; t = 1.802, P = 0.041). CONCLUSIONS: p300 plays a crucial role in the pathogenesis of HSPN. p300 can down-regulate the expression of resistance genes (AP-1 and TGF-ß1) by binding with GRα to prevent further renal injury and glucocorticoid resistance. Therefore, p300 is a promising new target in glucocorticoid therapy in HSPN.

Validation of the Boston University staging system in AL amyloidosis.

Objectives: We aimed to externally validate Lilleness' et al. Boston University (BU) prognostic score that replaced NT-proBNP with brain natriuretic peptide (BNP), which will allow centres without access to NT-proBNP to accurately stage and prognosticate AL amyloidosis. Patients/methods: Forty-four were identified that had BNP, NTpro-BNP and TnI taken simultaneously, with a mean follow up of 7.3 years. Median age of the 44 patients was 67 years and 27% were female, with 61% having cardiac involvement, and 61% having renal involvement. Results: Using the BU BNP-based staging system, we identified 12/44 (27%) of patients as stage I, 18/44 (41%) of patients as stage II and 14/44 (31%) of patients as stage III. This correlated closely with stratification via the Mayo score, with only one patient miscategorised (97.7% agreement, k = 0.98). Median overall survival for our BU stage I was not reached, stage II was 40 months and stage III was 5 months (long rank p = .0012). Mayo 2004 median overall survival was identical for stages I, II and III. Conclusion: We have provided external validation of the BU staging system, a novel prognostic scoring system incorporating BNP, instead of NT-proBNP, for AL amyloidosis.

Circulating miR-103a-3p contributes to angiotensin II-induced renal inflammation and fibrosis via a SNRK/NF-κB/p65 regulatory axis.

Although angiotensin II (AngII) is known to cause renal injury and fibrosis, the underlying mechanisms remain poorly characterized. Here we show that hypertensive nephropathy (HN) patients and AngII-infused mice exhibit elevated levels of circulating miR103a-3p. We observe a positive correlation between miR-103a-3p levels and AngII-induced renal dysfunction. miR-103a-3p suppresses expression of the sucrose non-fermentable-related serine/threonine-protein kinase SNRK in glomerular endothelial cells, and glomeruli of HN patients and AngII-infused mice show reduced endothelial expression of SNRK. We find that SNRK exerts anti-inflammatory effects by interacting with activated nuclear factor-κB (NF-κB)/p65. Overall, we demonstrate that AngII increases circulating miR-103a-3p levels, which reduces SNRK levels in glomerular endothelial cells, resulting in the over-activation of NF-κB/p65 and, consequently, renal inflammation and fibrosis. Together, our work identifies miR-103a-3p/SNRK/NF-κB/p65 as a regulatory axis of AngII-induced renal inflammation and fibrosis.

Do practical laboratory indices predict the outcomes of children with Henoch-Schönlein purpura?

Objectives: Henoch Schönlein Purpura (HSP) is the most common systemic vasculitis of childhood and often has a self-limiting course. We aimed to study whether practical laboratory parameters at the diagnosis predict disease course including recurrence and nephritis in addition to severe gastrointestinal involvement in children with HSP. Methods: This retrospective cohort study included 214 HSP patients, 43.5% (n = 93) female and 56.5% (n =121) male, who were diagnosed in our department. Laboratory parameters before treatment, including neutrophil, lymphocyte and platelet counts, mean platelet volume (MPV), neutrophil-to-lymphocyte (NLR), and platelet-to-lymphocyte ratios (PLR) were obtained retrospectively. Age at diagnosis, duration of follow-up, gender, preceding infections, medications, arthritis and arthralgia, abdominal pain, severe GI involvement, invagination, renal involvement and presence of nephritis, outcomes, and presence of recurrences were retrospectively recorded from medical files. Severe GI involvement was determined as severe colicky abdominal pain, bowel edema in ultrasonography or overt GI bleeding. A relapse was defined as a new flare of cutaneous lesions or other manifestations in a patient at least four asymptomatic weeks after the initial HSP episode. Results: Mean age at diagnosis was 7.6 ± 3.1 years. Biopsy-proven nephritis was found in 16 (7.5%) patients. Severe GI involvement was present in 77 (36%) patients, whereas only 12 (5.6%) patients were diagnosed with intussusception and in 29 (13.5%) patients, HSP recurred. Neutrophil count and NLR were found higher in HSP patients with severe gastrointestinal involvement and biopsy-proven nephritis. Additionally, only platelet count was lower and MPV was higher in patients with recurrent HSP. Conclusion: Elevated neutrophil count and NLR may be relevant markers for severe GI involvement and nephritis, whereas platelet count and MPV were the only laboratory parameters associated with disease recurrence.

Temporal Regulation of Glomerular and Cortical Tubulointerstitial Genes Involved in the Development of Nephrotoxic Serum Nephritis.

BACKGROUND/AIMS: Murine nephrotoxic nephritis (NTN) is a well-established model resembling chronic kidney disease. Investigating gene expression patterns separately in the glomerular and cortical tubulointerstitial structure could provide new knowledge about structure-specific changes in expression of genes in the NTN model. METHODS: Glomerular, cortical tubulointerstitial and whole kidney tissues from mice subjected to nephrotoxic serum (NTS) or phosphate buffered saline (PBS) were collected on day 7, 21 and 42 using laser microdissection (LMD). Total RNA was extracted and subjected to nCounter NanoString. Histology, immunohistochemistry, in situ hybridization and/or quantitative real time PCR (qRT PCR) were performed to confirm regulation of selected genes. RESULTS: LMD provided detailed information about genes that were regulated differently between structures over time. Some of the fibrotic and inflammatory genes (Col1a1, Col3a1 and Ccl2) were upregulated in both structures, whereas other genes such as Spp1 and Grem1 were differentially regulated suggesting spatial pathogenic mechanisms in the kidney. Downregulation of cortical tubulointerstitium genes involved in iron metabolism was detected along with iron accumulation. CONCLUSION: This study demonstrates several regulated genes in pathways important for the pathogenesis of the NTN model and that LMD identifies structure-specific changes in gene expression during disease development. Furthermore, this study shows the benefits of isolating glomeruli and cortical tubulointerstitium in order to identify gene regulation.

Krüppel-like factor 4 is a negative regulator of STAT3-induced glomerular epithelial cell proliferation.

Pathologic glomerular epithelial cell (GEC) hyperplasia is characteristic of both rapidly progressive glomerulonephritis (RPGN) and subtypes of focal segmental glomerulosclerosis (FSGS). Although initial podocyte injury resulting in activation of STAT3 signals GEC proliferation in both diseases, mechanisms regulating this are unknown. Here, we show that the loss of Krüppel-like factor 4 (KLF4), a zinc-finger transcription factor, enhances GEC proliferation in both RPGN and FSGS due to dysregulated STAT3 signaling. We observed that podocyte-specific knockdown of Klf4 (C57BL/6J) increased STAT3 signaling and exacerbated crescent formation after nephrotoxic serum treatment. Interestingly, podocyte-specific knockdown of Klf4 in the FVB/N background alone was sufficient to activate STAT3 signaling, resulting in FSGS with extracapillary proliferation, as well as renal failure and reduced survival. In cultured podocytes, loss of KLF4 resulted in STAT3 activation and cell-cycle reentry, leading to mitotic catastrophe. This triggered IL-6 release into the supernatant, which activated STAT3 signaling in parietal epithelial cells. Conversely, either restoration of KLF4 expression or inhibition of STAT3 signaling improved survival in KLF4-knockdown podocytes. Finally, human kidney biopsy specimens with RPGN exhibited reduced KLF4 expression with a concomitant increase in phospho-STAT3 expression as compared with controls. Collectively, these results suggest the essential role of KLF4/STAT3 signaling in podocyte injury and its regulation of aberrant GEC proliferation.