Novel therapeutic approaches to lupus glomerulonephritis: translating animal models to clinical practice

Animal models of lupus nephritis: the past, present and a future outlook

Lupus nephritis (LN) is the most severe end-organ pathology in Systemic Lupus Erythematosus (SLE). Research has enhanced our understanding of immune effectors and inflammatory pathways in LN. However, even with the best available therapy, the rate of complete remission for proliferative LN remains below 50%. A deeper understanding of the resistance or susceptibility of renal cells to injury during the progression of SLE is critical for identifying new targets and developing effective long-term therapies. The complex and heterogeneous nature of LN, combined with the limitations of clinical research, make it challenging to investigate the aetiology of this disease directly in patients. Hence, multiple murine models resembling SLE-driven nephritis are utilised to dissect LN's cellular and genetic mechanisms, identify therapeutic targets, and screen novel compounds. This review discusses commonly used spontaneous and inducible mouse models that have provided insights into pathogenic mechanisms and long-term maintenance therapies in LN.

Transcription Factors in the Pathogenesis of Lupus Nephritis and Their Targeted Therapy

Systemic lupus erythematosus (SLE) is a prototype inflammatory autoimmune disease, characterized by breakdown of immunotolerance to self-antigens. Renal involvement, known as lupus nephritis (LN), is one of the leading causes of morbidity and a significant contributor to mortality in SLE. Despite current pathophysiological advances, further studies are needed to fully understand complex mechanisms underlying the development and progression of LN. Transcription factors (TFs) are proteins that regulate the expression of genes and play a crucial role in the development and progression of LN. The mechanisms of TF promoting or inhibiting gene expression are complex, and studies have just begun to reveal the pathological roles of TFs in LN. Understanding TFs in the pathogenesis of LN can provide valuable insights into this disease's mechanisms and potentially lead to the development of targeted therapies for its management. This review will focus on recent findings on TFs in the pathogenesis of LN and newly developed TF-targeted therapy in renal inflammation.

Kidney targeting of formoterol containing polymeric nanoparticles improves recovery from ischemia reperfusion-induced acute kidney injury in mice

The β₂ adrenergic receptor agonist, formoterol, is an inducer of mitochondrial biogenesis and restorer of mitochondrial and kidney function in acute and chronic models of kidney injury. Unfortunately, systemic administration of formoterol has the potential for adverse cardiovascular effects, increased heart rate, and decreased blood pressure. To minimize these effects, we developed biodegradable and biocompatible polymeric nanoparticles containing formoterol that target the kidney, thereby decreasing the effective dose, and lessen cardiovascular effects while restoring kidney function after injury. Male C57Bl/6 mice, treated with these nanoparticles daily, had reduced ischemia-reperfusion-induced serum creatinine and kidney cortex kidney injury molecule-1 levels by 78% and 73% respectively, compared to control mice six days after injury. With nanoparticle therapy, kidney cortical mitochondrial number and proteins reduced by ischemic injury, recovered to levels of sham-operated mice. Tubular necrosis was reduced 69% with nanoparticles treatment. Nanoparticles improved kidney recovery even when the dosing frequency was reduced from daily to two days per week. Finally, compared to treatment with formoterol-free drug alone, these nanoparticles did not increase heart rate nor decrease blood pressure. Thus, targeted kidney delivery of formoterol-containing nanoparticles is an improvement in standard formoterol therapy for ischemia-reperfusion-induced acute kidney injuries by decreasing the dose, dosing frequency, and cardiac side effects.

Dual-Regulated Functionalized Liposome-Nanoparticle Hybrids Loaded with Dexamethasone/TGFβ1-siRNA for Targeted Therapy of Glomerulonephritis

Mesangial cell (MC)-mediated glomerulonephritis is a frequent cause of end-stage renal disease, with immune inflammatory damage and fibrosis as its basic pathological processes. However, the treatment of glomerulonephritis remains challenging owing to limited drug accumulation and serious side effects. Hence, the specific codelivery of "anti-inflammatory/antifibrosis" drugs to the glomerular MC region is expected to yield better therapeutic effects. In this study, liposome-nanoparticle hybrids (Au-LNHy) were formed by coating the surface of gold nanoparticles with a phospholipid bilayer; the Au-LNHys formed were comodified with PEG and α8 integrin antibodies to obtain gold nanoparticle immunoliposomes (Au-ILs). Next, the Au-ILs were loaded with dexamethasone and TGFβ1 siRNA to obtain DXMS/siRNA@Au-ILs. Our results showed that the functionalized nanoparticles had a core-shell structure, a uniform and suitable particle size, low cytotoxicity, and good MC entry, and lysosomal escape abilities. The nanoparticles were found to exhibit enhanced retention in glomerular MCs due to anti-α8 integrin antibody mediation. In vivo and in vitro pharmacodynamic studies showed the enhanced efficacy of DXMS/siRNA@Au-ILs modified with α8 integrin antibodies in the treatment of glomerulonephritis. In addition, DXMS/siRNA@Au-ILs were capable of effectively reducing the expression levels of TNF-α, TGF-β1, and other cytokines, thereby improving pathological inflammatory and fibrotic conditions in the kidney, and significantly mediating the dual regulation of inflammation and fibrosis. In summary, our results demonstrated that effectively targeting the MCs of the glomerulus for drug delivery can inhibit local inflammation and fibrosis and produce better therapeutic effects, providing a new strategy and promising therapeutic approach for the development of targeted therapies for glomerular diseases.

An evaluation of a novel nanoformulation of imatinib mesylate in a mouse model of lupus nephritis

Studies have suggested imatinib mesylate (ImM) as a potential treatment for systemic lupus erythematosus nephritis (SLEN). However, ImM has limited renal excretion. The goal of the current research was to develop an ImM containing nanoformulation, conduct studies to evaluate pharmacokinetics, and determine whether kidney deposition can be enhanced in a mouse model of SLEN. A fish oil-based ImM oil-in-water nanoemulsion was developed and characterized for particle size, zeta potential, pH, and stability. MRL/MpJ-Faslrp (model of SLEN) and MRL/MpJ (control) mice (12-13 weeks) received one dose of ImM as either a nanoemulsion or naked drug. Pharmacokinetics and kidney deposition studies were performed. Statistics were conducted with a student's T-test. The nanoemulsion characteristics included particle size range of 60-80 nm, zeta potential of -6.6 to -7.8 mV, polydispersity index < 0.3, 3-day stability at 4 °C, and limited ImM leakage from the nanoemulsion in serum. Pharmacokinetics of the nanoformulation showed changes to pharmacokinetic parameters suggesting reduced systemic exposures (with reduced potential for toxicities) to ImM. Kidney deposition of ImM was threefold higher after 4 h in the MRL/MpJ-Faslrp mice that received the nanoformulation vs. naked drug. The current study showed encouraging results for development of a stable and well-characterized nanoemulsion for optimizing kidney deposition of ImM. Future strategies will define dose-efficacy and dose-toxicity relationships and evaluate approaches to further enhance kidney delivery and optimize deposition to the mesangial location of the kidney.

Low dose mycophenolate mofetil versus cyclophosphamide in the induction therapy of lupus nephritis in Nepalese population: a randomized control trial

BACKGROUND

The management of proliferative lupus nephritis (LN) comprises timely and coordinated immunosuppressive therapy. This study aimed to evaluate and compare the effectiveness and safety profile of low dose mycophenolate mofetil (MMF) and cyclophosphamide (CYC) in induction therapy of LN in Nepalese population.

METHODS

We conducted a prospective, open-label, randomized trial over a period of one and half years. Forty-nine patients with class III to V lupus nephritis were enrolled, out of which 42 patients (21 in each group) could complete the study. CYC was given intravenously as a monthly pulse and MMF was administered orally in the tablet form in the maximum daily dose of 1.5 g in two divided doses.

RESULTS

The mean age of the patients was 25.43 ± 10.17 years with female to male ratio of 7.3:1. Mean baseline serum creatinine was 1.58 ± 1.38 mg/dL and eGFR was 62.38 ± 26.76 ml/min/1.73m². Mean 24-h urinary protein was 4.35 ± 3.71 g per 1.73 m² body surface area. At 6 months, serum creatinine (mg/dL) decreased from 1.73 to 0.96 in CYC and from 1.24 to 0.91 in the MMF group with improvement in eGFR (ml/min/1.73 m²) from 60.33 to 88.52 in CYC and from 64.42 to 89.09 in MMF group. Twenty-four-hour urinary protein (gm/1.73m²) reduced from 4.47 to 0.94 in CYC and from 4.5 to 0.62 in the MMF group. Primary end point was achieved in higher percentage of patients with MMF than CYC (28.6% vs. 19%) while equal proportion of patients (67% in each group) achieved secondary end point in both groups. Number of non-responders was higher in CYC group than in the MMF group (14.3% vs. 4.8%). There was no difference in the rate of achievement of secondary end point in both CYC and MMF groups (3.16 vs. 3.05 months). The occurrence of adverse events was higher in the CYC than in MMF group (56 vs. 15 events).

CONCLUSION

Present study has concluded that MMF, used in relatively lower dose, is equally effective in inducing remission with reduction of proteinuria and improvement of kidney function with lesser adverse events than CYC in the induction therapy of proliferative lupus nephritis.

TRIAL REGISTRATION

Retrospectively registered to ClinicalTrials.gov PRS. NCT03200002 (Registered date: June 28, 2017).

Mouse models of lupus: what they tell us and what they don't

Lupus is a complex heterogeneous disease characterised by autoantibody production and immune complex deposition followed by damage to target tissues. Animal models of human diseases are an invaluable tool for defining pathogenic mechanisms and testing of novel therapeutic agents. There are perhaps more applicable murine models of lupus than any other human disease. There are spontaneous models of lupus, inducible models of lupus, transgenic-induced lupus, gene knockout induced lupus and humanised mouse models of lupus. These mouse models of lupus have contributed significantly to our knowledge of the pathogenesis of lupus and served as valuable preclinical models for proof of concept for new therapies. Despite their utility, mouse models of lupus have their distinct limitations. Although similar, mouse and human immune systems are different and thus one cannot assume a mechanism for disease in one is translatable to the other. Efficacy and toxicity of compounds can vary significantly between humans and mice, also limiting direct translation. Finally, the heterogeneous aspects of human lupus, both in clinical presentation, underlying pathogenesis and genetics, are not completely represented in current mouse models. Thus, proving a therapy or mechanism of disease in one mouse model is similar to proving a mechanism/therapy in a limited subset of human lupus. These limitations, however, do not marginalise the importance of animal models nor the significant contributions they have made to our understanding of lupus.

Outcome of low dose cyclophosphamide for induction phase treatment of lupus nephritis, a single center study

Background

The current standard for induction phase treatment of lupus nephritis is steroid combined with mycophenolate mofetil or pulse intravenous cyclophosphamide (IVC). The lowest dose of IVC recommended for induction therapy is that used in the Euro-Lupus Trial. It is not known whether same cumulative dose of IVC would be effective when given over six months.

Methods

We carried out a prospective, observational study on 41 patients of biopsy-proven lupus nephritis (class III, IV, V or mixed). For induction, patients received six pulses of monthly IVC (500 mg each), along with steroid. Patients were followed up monthly until one month beyond completion of the sixth pulse. The outcomes assessed were complete remission (proteinuria < 200 mg/day or urine albumin nil with serum albumin >35 gm/L, stable estimated glomerular filtration rate (eGFR) if normal at baseline or increase in eGFR by 25 % if abnormal at baseline and normal urinary sediment), response (complete or partial remissions), complications of therapy and death.

Results

Twenty two patients (53.7 %) had class IV nephritis. Eighteen patients (43.9 %) achieved complete remission, 16 (39.0 %) achieved partial remission, yielding an overall response rate of 82.9 %. Nephrotic range proteinuria (UTP ≥ 3 g/day) and severe hypoalbuminemia (serum albumin < 20 g/L) at baseline influenced remission (p <0.05). Infection, seen in 12 patients (29.3 %), was the most common complication. Four deaths (9.6 %) were observed, all due to infection.

Conclusions

For induction phase treatment, Nepalese patients with lupus nephritis responded favorably to steroid and low dose IVC of 3 grams given as six monthly pulses.

Efficacy and safety of mycophenolate mofetil versus cyclophosphamide for induction therapy of lupus nephritis: a meta-analysis of randomized controlled trials

INTRODUCTION

Whether mycophenolate mofetil is superior to cyclophosphamide as induction therapy for lupus nephritis (LN) remains controversial.

OBJECTIVE

Our objective was to investigate the efficacy and safety of mycophenolate mofetil compared with cyclophosphamide as induction therapy for LN patients.

METHODS

Randomized controlled trials (RCTs) on humans were identified in searches of PubMed/MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials (all to 1 December 2011). Studies that compared the efficacy and safety between mycophenolate mofetil and cyclophosphamide as induction therapy in LN patients were selected. Methodological quality of the included trials was assessed according to Cochrane criteria and Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. The fixed effects model was applied for pooling where there was no significant heterogeneity, otherwise the random effects model (Dersimonian and Laird method) was performed.

RESULTS

Seven trials were identified, including 725 patients. The Dersimonian and Laird method was applied for renal remission in the presence of significant heterogeneity, and no statistically significant differences were distinguished between mycophenolate mofetil and cyclophosphamide. To explore the possible source of heterogeneity, meta-regression was performed. It was suggested that no obvious study- or patient-level factors could explain interstudy heterogeneity with statistical significance. Among all these factors, the mode of administration of cyclophosphamide could explain most of the heterogeneity, although the coefficient was insignificant. Therefore, we performed a sensitivity analysis by excluding the trial in which cyclophosphamide was administered orally instead of intravenously, which suggested that mycophenolate mofetil was more effective than intravenous cyclophosphamide for inducing complete remission (relative risk [RR] 1.72; 95% CI 1.17, 2.55; p = 0.006) and complete or partial remission (RR 1.18; 95% CI 1.04, 1.35; p = 0.01). In addition, mycophenolate mofetil was superior to cyclophosphamide for significantly reducing end-stage renal disease (ESRD) or death (RR 0.64; 95% CI 0.41, 0.98; p = 0.04). For the safety comparison, lower risks of leukopenia, amenorrhoea and alopecia, and a higher risk of diarrhoea were found with mycophenolate mofetil. No statistical differences in infection and gastrointestinal symptoms were distinguished between mycophenolate mofetil and cyclophosphamide. The relatively small number and the open-label fashion of eligible RCTs may limit the value of our meta-analysis.

CONCLUSIONS

Mycophenolate mofetil is superior to intravenous cyclophosphamide for inducing renal remission, and has a significant advantage over cyclophosphamide for reducing ESRD or death. Furthermore, mycophenolate mofetil has lower risks of leukopenia, amenorrhoea and alopecia, but a higher risk of diarrhoea than cyclophosphamide. However, our conclusions need to be proved further in larger well designed trials.

From the Large Scale Expression Analysis of Lupus Nephritis to Targeted Molecular Medicine

Lupus nephritis (LN) is one of the most severe complications of systemic lupus erythematosus (SLE). Current treatments for LN lack sufficient efficacy as they do not necessarily target the LN responsible pathways and therapeutic responses vary widely in the patient population. LN mouse models have been useful in delineating disease pathogenesis and for testing novel therapies, but they do not entirely represent the events happening in human LN. This review describes how recently developed systems biology technologies can help to integrate current knowledge with large scale experimental data to generate new hypotheses and insight into the regulatory events occurring in LN.