Role and mechanisms of SGLT-2 inhibitors in the treatment of diabetic kidney disease.

Diabetic kidney disease (DKD) is a chronic inflammatory condition that affects approximately 20-40% of individuals with diabetes. Sodium-glucose co-transporter 2 (SGLT-2) inhibitors, emerging as novel hypoglycemic agents, have demonstrated significant cardiorenal protective effects in patients with DKD. Initially, it was believed that the efficacy of SGLT-2 inhibitors declined as the estimated glomerular filtration rate (eGFR) decreased, which led to their preferential use in DKD patients at G1-G3 stages. However, recent findings from the DAPA-CKD and EMPA-KIDNEY studies have revealed equally beneficial cardiorenal effects of SGLT-2 inhibitors in individuals at stage G4 DKD, although the underlying mechanism behind this phenomenon remains unclear. In this comprehensive analysis, we provide a systematic review of the mechanisms and functioning of SGLT-2 inhibitors, potential renal protection mechanisms, and the therapeutic efficacy and safety of SGLT-2 inhibitors in kidney diseases, with a particular focus on stage G4 DKD. Gaining a deeper understanding of the renal protective effect of SGLT-2 inhibitors and their underlying mechanisms is highly significance for the successful utilization of these inhibitors in the treatment of diverse kidney disorders.

The Therapeutic Potential of CDK4/6 Inhibitors, Novel Cancer Drugs, in Kidney Diseases.

Inflammation is a crucial pathological feature in cancers and kidney diseases, playing a significant role in disease progression. Cyclin-dependent kinases CDK4 and CDK6 not only contribute to cell cycle progression but also participate in cell metabolism, immunogenicity and anti-tumor immune responses. Recently, CDK4/6 inhibitors have gained approval for investigational treatment of breast cancer and various other tumors. Kidney diseases and cancers commonly exhibit characteristic pathological features, such as the involvement of inflammatory cells and persistent chronic inflammation. Remarkably, CDK4/6 inhibitors have demonstrated impressive efficacy in treating non-cancerous conditions, including certain kidney diseases. Current studies have identified the renoprotective effect of CDK4/6 inhibitors, presenting a novel idea and potential direction for treating kidney diseases in the future. In this review, we briefly reviewed the cell cycle in mammals and the role of CDK4/6 in regulating it. We then provided an introduction to CDK4/6 inhibitors and their use in cancer treatment. Additionally, we emphasized the importance of these inhibitors in the treatment of kidney diseases. Collectively, growing evidence demonstrates that targeting CDK4 and CDK6 through CDK4/6 inhibitors might have therapeutic benefits in various cancers and kidney diseases and should be further explored in the future.

Autophagy in peritoneal fibrosis.

Peritoneal dialysis (PD) is a widely accepted renal replacement therapy for patients with end-stage renal disease (ESRD). Morphological and functional changes occur in the peritoneal membranes (PMs) of patients undergoing long-term PD. Peritoneal fibrosis (PF) is a common PD-related complication that ultimately leads to PM injury and peritoneal ultrafiltration failure. Autophagy is a cellular process of "self-eating" wherein damaged organelles, protein aggregates, and pathogenic microbes are degraded to maintain intracellular environment homeostasis and cell survival. Growing evidence shows that autophagy is involved in fibrosis progression, including renal fibrosis and hepatic fibrosis, in various organs. Multiple risk factors, including high-glucose peritoneal dialysis solution (HGPDS), stimulate the activation of autophagy, which participates in PF progression, in human peritoneal mesothelial cells (HPMCs). Nevertheless, the underlying roles and mechanisms of autophagy in PF progression remain unclear. In this review, we discuss the key roles and potential mechanisms of autophagy in PF to offer novel perspectives on future therapy strategies for PF and their limitations.

Revisited Cyclophosphamide in the Treatment of Lupus Nephritis.

Lupus nephritis (LN) is the most common serious complication of systemic lupus erythematosus (SLE). The pathogenesis of LN is complex, and the majority causes of LN are the renal deposition of circulating or/and in situ-formed immune complexes. These immune complexes trigger glomerular and tubulointerstitial inflammation, which finally leads to proteinuria and loss of renal function. Despite the emergence of new biological agents, cyclophosphamide (CY), an alkylating agent, is still the first-line drug widely used to treat patients with severe LN. In this review, we outline the application history, molecular structure, and pharmacokinetics of CY in the treatment of LN. We also detail its latest known immunopharmacological mechanisms, with a focus on supplemental regulation and inhibition of CD4 and CD8 positive T cells, differences in the use of various guidelines, and the combination with other drugs. The side effects of CY are also mentioned in this review.

The expression of renal Epstein-Barr virus markers in patients with lupus nephritis.

The aim of this study was to investigate the role of renal Epstein-Barr virus (EBV) infection in the pathogenesis of lupus nephritis (LN). A total of 58 renal tissue samples from patients with LN, seven normal renal tissue samples from patients with non-glomerular hematuria and 37 renal tissue samples from patients with minimal change nephropathy were collected. The expression of EBV-latent membrane protein-1 (EBV-LMP1) and EBV-encoded RNA 1 (EBER-1) in the renal tissue was examined by immunohistochemistry (IHC) and in situ hybridization (ISH), respectively. The sera levels of anti-nuclear antibody as well as antibodies to extractable nuclear antigen in patients with LN were also measured. An equivalence test showed that the results from the IHC and the ISH analyses had strong agreement. The positive rates of renal EBER-1 and EBV-LMP1 in the LN patients were significantly higher than those of the normal and minimal change nephropathy patients (P<0.001), while no significant difference was identified between those of the normal and minimal change nephropathy groups (P>0.05). The positive rates of EBV-LMP1 and EBER-1 in the renal tissues of patients with LN were not determined to be significantly different between the relapse (immunosuppressant-treated) and initial onset (non-treated) patients, between the patients with and without concurrent infection, and among the patients with different age ranges (P>0.05). The proportion of LN patients positive for anti-Sm antibody was significantly higher in the renal EBV-positive group than in the EBV-negative group (P<0.05), while the proportions of LN patients positive for the other autoantibodies that were examined were not identified to be significantly different between these two groups (P>0.05). The present study shows that renal EBV infection may contribute to the pathogenesis of LN by inducing anti-Sm antibody production.

Continuation of immunosuppressive treatment may be necessary in IgA nephropathy patients with remission of proteinuria: Evaluation by repeat renal biopsy.

The present study aimed to evaluate the effects of an individualized, low-dose multi-drug immunosuppressive regimen for the treatment of immunoglobulin A nephropathy (IgAN). A preliminary investigation of the course of IgAN following immunosuppressive treatment was conducted based on repeat renal biopsies. Clinical and pathological data of 17 patients with IgAN who received repeat renal biopsies were analyzed retrospectively. In addition to basic treatment, 16 patients regularly received an individualized low-dose immunosuppressive regimen according to their clinical manifestations and pathological patterns following the first biopsy. Clinical parameters, including 24-h urinary protein excretion and levels of serum albumin, uric acid and total cholesterol were collected. Glomerular deposits of IgA and C3, as well as the activity and chronicity indexes of renal lesions were evaluated by semi-quantitative methods. The 24-h urinary protein excretion of the patients decreased significantly from the first biopsy (2.53±2.17 g/day) to the repeated biopsy (0.26±0.55 g/day) (P<0.001). Deposits of IgA and C3 in the glomerulus were persistent, but were reduced in quantity at the second biopsy. Although active renal lesions were observed in the majority of patients, the activity index decreased significantly from 3.18±1.33 prior to therapy to 2.47±0.80 following therapy (P<0.05), while the chronicity index did not change significantly (2.59±2.00 versus 2.76±1.89, respectively). The individualized, low-dose multi-drug immunosuppressive regimen used in the present study significantly minimized proteinuria, stabilized renal function and alleviated histological lesions in patients with IgAN without causing overt adverse effects during the short-term follow-up. In addition to proteinuria, renal pathological changes should be appraised when considering the withdrawal of immunosuppressants from IgAN treatment.

[Interleukin-18-induced transdifferentiation in renal proximal tubular cells is mediated by activation of p38MAPK pathway].

OBJECTIVE: To explore the effect of p38MAPK signaling pathway in interleukin-18-induced transdifferentiation in renal proximal tubular cells. METHODS: Human proximal tubular epithelial cell line (HK-2 cells) was cultured in vitro. After preincubated with SB203580 (0, 5, 10, 20 micromol/L) for 30 minutes, cells were exposed to IL-18 (100 ng/ml) for 24, 48 and 72 hours respectively. The expressions of a-smooth actin (alpha-SMA) in cultured HK-2 cells were assessed by RT-PCR and ELISA. RESULTS: IL-18-induced expressions of a-SMA mRNA and protein were inhibited obviously by a dose-dependent manner when HK-2 cells were incubated with SB203580 (0, 5, 10, 20 micromol/L) and IL-18 (100 ng/ml) for different time (P < 0.05). CONCLUSION: IL-18-induced transdifferentiation of renal tubular epithelial cells (RTECs) is suppressed obviously by blocking p38MAPK signaling pathways. IL-18-induced transdifferentiation of RTECs is probably mediated, at least in part, through the activation of p38MAPK signaling pathways.

[The effect of IL-18 on E-cadherin expression and its possible intracellular pathway in HK-2 cells].

AIM: To explore the effect of NF-kappaB signaling pathway in interleukin-18-induced transdifferentiation in renal proximal tubular cells. METHODS: In IL-18 stimulation groups, HK-2 cells were challenged with different concentrations (0, 1, 10, 100 microg/L) of IL-18 for 72 h; In SN50 preincubation groups, HK-2 cells were incubated with 100 mg/L SN50 for 30 min before IL-18 was added. At the end of the incubation, the expression of E-cadherin was determined by the combination of immunocytochemistry and RT-PCR. RESULTS: Percentage of E-cadherin positive expression HK-2 cells was decreased by IL-18 in dosage dependant manner. Expression of E-cadherin mRNA in HK-2 cells was also decreased by IL-18 in dosage dependant manner. Recovered the mostly part of expression of E-cadherin was found after HK-2 cells were pretreated with SN50. CONCLUSION: IL-18-induced transdifferentiation of RTECs is suppressed by blocking NF-kappaB signaling pathway. IL-18-induced transdifferentiation of RTECs at least is partly via NF-kappaB pathway.

Effects of interleukin 18 on injury and activation of human proximal tubular epithelial cells.

BACKGROUND/AIMS: Injury and activation of tubular proximal epithelial cells (TEC) play central roles in renal tubulointerstitial fibrosis (TIF), but its mechanisms remain obscure. Interleukin 18 (IL-18) is overproduced during chronic kidney diseases (CKD), but how IL-18 affects the biological behaviour of TEC is not clear. The aim of the present study is to reveal the role of IL-18 in renal TIF. METHODS: The expressions of IL-18 and IL-18 receptor in TEC were detected by immunohistochemical staining in vivo and by reverse transcriptase polymerase chain reaction (RT-PCR) in vitro. TEC line (HK-2 cells) were incubated without or with IL-18. Cell proliferation and cell cycle were evaluated by methyl thiazolyl tetrazolium assay and flow cytometric analysis, respectively. Cell apoptosis was assessed by Hoechst 33258 staining. Expression of alpha-smooth muscle actin was evaluated by RT-PCR, immunocytochemical staining and flow cytometric analysis, respectively. Type I collagen, fibronectin, MCP-1 and RANTES in cultured supernatants were measured by enzyme-linked immunosorbent assay. RESULTS: IL-18 expression in TEC increased significantly in CKD state. IL-18 receptor was constitutively expressed in normal proximal TEC, and its expression increased strongly in CKD state. Proliferation and cell cycle of HK-2 cells were not affected by IL-18. Cell apoptosis, alpha-smooth muscle actin expression, type I collagen and fibronectin production as well as MCP-1 secretion were promoted by IL-18 in dosage- and/or time-dependent manners, but RANTES secretion was not affected. CONCLUSION: IL-18 may play a crucial role in the process of TIF by promoting TEC injury and activation, and could be a target of the therapeutic approaches against TIF.

[Evaluation of the relationship between IL-18 levels in urine and parameters of renal pathological changes in patients with lupus nephritis].

AIM: To evaluate the relationship between IL-18 levels in urine and parameters of renal pathological changes in patients with lupus nephritis (LN). METHODS: IL-18 levels in morning free urine and 24-hour's urine in 19 normal persons and 55 patients with LN were measured by ELISA. The correlation between IL-18 levels and parameters of renal pathological changes, namely activity index (AI) and chronicity index (CI), were analyzed by liner correlation analysis method. RESULTS: IL-18 levels in morning free urine and 24-hour's urine in LN group were elevated significantly compared with control group. In both groups IL-18 levels in morning free urine were (247.1+/-317.5) ng/L and (20.3+/-14.5) ng/L, respectively, P<0.001; those in 24-hour's urine were (192.1+/-170.1) ng/d and (21.0+/-3.8) ng/d, respectively, (P<0.001). There was close positive correlation between IL-18 levels in morning free urine and 24-hour's urine and LN patient's AI (for morning free urine: r=0.602, P<0.001; for 24-hour's urine: r=0.461, P<0.005) but there was no correlation between IL-18 levels in morning urine and 24-hour's urine and CI (P>0.05). Patients with LN were divided into three groups (high, moderate and low) according to AI value. There was distinct difference of IL-18 levels in urine among the three groups: IL-18 levels in morning urine were (69.2+/-82.7) ng/L, (193.5+/-106.1) ng/L and (580.7+/-453.1) ng/L, respectively, (P<0.001); those in 24-hour's urine were (103.5+/-141.4) ng/d, (188.8+/-124.0) ng/d and (333.1+/-183.2) ng/d, respectively. CONCLUSION: It is very simple and convenient to detect IL-18 levels in morning free urine, so it is a good method for evaluating renal pathological activity of LN.

Effects of specific interleukin-1beta-converting enzyme inhibitor on ischemic acute renal failure in murine models.

AIM: To study the effect of selective interleukin-1beta-converting enzyme (ICE, caspase-1) inhibitor on ischemic acute renal failure (ARF). METHODS: Mouse models of ischemic ARF were treated with the specific ICE inhibitor AC-YVAD-CMK. A renal function assay and renal morphological studies were employed to estimate the renal protective effect of AC-YVAD-CMK. The survival rate of mouse models was also analyzed by a time series test. Furthermore, renal ICE activity, mature interleukin-18 (IL-18) protein expression and interferon-gamma (IFN-gamma) mRNA expression were also detected by fluorescent enzyme-linked immunosorbent assay (ELISA), ELISA, and semi-quantitative reverse transcription-polymerase chain reaction, respectively. RESULTS: The levels of blood urea nitrogen (BUN) and serum creatinine (Scr) increased remarkably in the model controls compared with the sham-operated groups (P<0.01). Typical renal tubular necrosis was found in the model controls. Renal ICE activity, mature IL-18 protein expression, and IFN-gamma mRNA expression were also increased significantly in the model controls compared with the sham-operated groups. The levels of BUN and Scr in the AC-YVAD-CMK therapy group were decreased significantly compared with the untreated model controls (P<0.01). Renal tubulointerstitial lesion was also attenuated significantly (P<0.05). AC-YVAD-CMK therapy alleviated the clinical features of ARF, and increased the survival rate (P<0.01). Furthermore, AC-YVAD-CMK therapy also decreased ICE activity, mature IL-18 protein expression, and IFN-gamma mRNA expression in renal tissue (P<0.05). CONCLUSION: The selective ICE inhibitor AC-YVAD-CMK can effectively protect the kidney from acute ischemic lesions. This protective effect is associated with decreased renal ICE activity and suppressed IL-18 maturation and IFN-gamma mRNA transcription.