Circulating factors in sera or peripheral blood mononuclear cells in patients with membranous nephropathy or diabetic nephropathy

IL-23/IL-17 in a Paradoxical Association with Primary Membranous Nephropathy

Primary membranous nephropathy (PMN), an autoimmune disease, is the most common cause of nephrotic syndrome in middle-aged non-diabetic adults. PMN pathophysiology includes Th1/Th2 paradigm. The IL-23/IL-17 pathway is implicated in autoimmune kidney disorders, but no study has examined its relationship with PMN. In several unrelated studies, PMN patients reported to have paradoxical IL-17 levels. This manuscript describes the best possible association of IL-23/IL-17 axis with PMN. Biopsy-proven PMN patients and age, gender-matched healthy controls were enrolled. Serum-PLA2R (Euroimmune, Germany), IL-23 and IL-17 (R&D; USA), was measured using ELISA along with biochemical parameters. Appropriate statistical tools were used for analysis. One hundred eighty-nine PMN patients (mean age 41.70 ± 12.53 years) and 100 controls (mean age 43.92 ± 10.93 years) were identified. One hundred forty were PLA2R-related. PMN patients had median proteinuria, serum albumin, and creatinine of 6.12 (3.875, 9.23) g/day, 2.32 (1.96, 2.9) g/dl, and 0.89 (0.7, 1.1) mg/dl, respectively. IL-17, but not IL-23, was significantly increased in PMN patients compared to controls (IL-17, median: 12.07 pg/ml (9.75, 24.56) vs median: 9.75 pg/ml (8.23, 17.03) p = 0.0002); (IL23, median: 6.04 pg/ml (4.22, 10.82) vs median: 5.46 pg/ml (3.34, 9.96) p = 0.142). IL-17 and IL-23 correlated significantly (p 0.05) in PMN patients, and similar trend was seen when grouped into PLA2R-related and -unrelated groups. The levels of IL-23 (p = 0.057) and IL-17 (p = 0.004) were high in MN patients that did not respond to the treatment. The current finding may indicate or suggest the involvement of IL-23/IL-17 PMN pathogenesis. A comprehensive investigation is needed to evaluate IL-23/IL-17 axis with renal infiltrating immune cells, and external stimuli.

A Comprehensive Phenotypic and Functional Immune Analysis Unravels Circulating Anti-Phospholipase A2 Receptor Antibody Secreting Cells in Membranous Nephropathy Patients

Introduction

Primary membranous nephropathy (MN) is characterized by the presence of antipodocyte antibodies, but studies describing phenotypic and functional abnormalities in circulating lymphocytes are limited.

Methods

We analyzed 68 different B- and T-cell subsets using flow cytometry in 30 MN patients (before initiating immunosuppression) compared with 31 patients with non–immune-mediated chronic kidney disease (CKD) and 12 healthy individuals. We also measured 19 serum cytokines in MN patients and in healthy controls. Lastly, we quantified the ex vivo production of phospholipase A2 receptor (PLA2R)-specific IgG by plasmablasts (measuring antibodies in culture supernatants and by the newly developed FluoroSpot assay [AutoImmun Diagnostika, Strasberg, Germany]) and assessed the circulating antibody repertoire by phage immunoprecipitation sequencing (PhIP-Seq).

Results

After adjusting for multiple testing, plasma cells and regulatory B cells (B_REG) were significantly higher (P < 0.05) in MN patients compared with both control groups. The percentages of circulating plasma cells correlated with serum anti-PLA2R antibody levels (P = 0.042) and were associated with disease activity. Ex vivo–expanded PLA2R-specific IgG-producing plasmablasts generated from circulating PLA2R-specific memory B cells (mBCs) correlated with serum anti-PLA2R IgG antibodies (P < 0.001) in MN patients. Tumor necrosis factor-α (TNF-α) was the only significantly increased cytokine in MN patients (P < 0.05), whereas there was no significant difference across study groups in the autoantibody and antiviral antibody repertoire.

Conclusion

This extensive phenotypic and functional immune characterization shows that autoreactive plasma cells are present in the circulation of MN patients, providing a new therapeutic target and a candidate biomarker of disease activity.

Altered Mitochondrial Function, Mitochondrial DNA and Reduced Metabolic Flexibility in Patients With Diabetic Nephropathy

The purpose of this study was to determine if mitochondrial dysfunction plays a role in diabetic nephropathy (DN), a kidney disease which affects > 100 million people worldwide and is a leading cause of renal failure despite therapy. A cross-sectional study comparing DN with diabetes patients without kidney disease (DC) and healthy controls (HCs); and renal mesangial cells (HMCs) grown in normal and high glucose, was carried out. Patients with diabetes (DC) had increased circulating mitochondrial DNA (MtDNA), and HMCs increased their MtDNA within 24 h of hyperglycaemia. The increased MtDNA content in DCs and HMCs was not functional as transcription was unaltered/down-regulated, and MtDNA damage was present. MtDNA was increased in DC compared to HC, conversely, patients with DN had lower MtDNA than DC. Hyperglycaemic HMCs had fragmented mitochondria and TLR9 pathway activation, and in diabetic patients, mitophagy was reduced. Despite MtDNA content and integrity changing within 4 days, hyperglycaemic HMCs had a normal bio-energetic profile until 8 days, after which mitochondrial metabolism was progressively impaired. Peripheral blood mononuclear cells (PBMCs) from DN patients had reduced reserve capacity and maximal respiration, loss of metabolic flexibility and reduced Bioenergetic Health Index (BHI) compared to DC. Our data show that MtDNA changes precede bioenergetic dysfunction and that patients with DN have impaired mitochondrial metabolism compared to DC, leading us to propose that systemic mitochondrial dysfunction initiated by glucose induced MtDNA damage may be involved in the development of DN. Longitudinal studies are needed to define a potential cause–effect relationship between changes in MtDNA and bioenergetics in DN.

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Diabetic nephropathy may be a disease of acquired MtDNA damage and bioenergetic deficit.

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MtDNA content is increased in blood cells of diabetes patients and hyperglycaemic renal cells.

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Hyperglycaemia leads to renal cell MtDNA damage and subsequent bioenergetic dysfunction.

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Diabetic nephropathy patients have reduced circulating MtDNA , BHI and metabolic flexibility bioenergetic dysfunction and reduced metabolic flexibility and BHI.

Interferon-α-induced B-lymphocyte stimulator expression and mobilization in healthy and systemic lupus erthymatosus monocytes

OBJECTIVE

The aim of this study was to investigate the cellular populations and regulatory factors responsible for B-lymphocyte stimulator (BLyS) overexpression in SLE patients.

METHODS

Surface and intracellular BLyS levels were quantified by flow cytometry in healthy and SLE monocytes cultured in the presence of TNF-α, IFN-α, IFN-γ, GM-CSF and SLE immune complexes (SLE-ICs), while soluble BLyS was measured by ELISA. Also, both surface and intracellular BLyS expression by different cell subsets was determined in 23 SLE patients and 16 healthy controls. Disease activity was assessed using classic BILAG index.

RESULTS

In vitro experiments using healthy monocytes showed that IFN-α and SLE-ICs induced a progressive increase in surface-bound BLyS with respect to the intracellular stores. IFN-α-treated SLE monocytes, especially from patients with high anti-dsDNA levels or disease activity, exhibited higher intracellular levels of BLyS that was mobilized to the membrane more rapidly and subsequently released. Furthermore, ex vivo analysis of SLE patients revealed up-regulated BLyS expression in B cells, myeloid and plasmacytoid dendritic cells (DCs), whereas active patients had an increased surface:intracellular BLyS ratio in monocytes and myeloid DCs.

CONCLUSION

Monocyte BLyS induction and mobilization from intra- to extracellular compartments seems to be influenced by IFN-α and disease activity or anti-dsDNA levels. Accordingly, monocytes and myeloid DCs from active patients presented the highest membrane-bound:intracellular BLyS ratio. In addition, expression levels in several blood cells support the existence of generalized immune stimulation in SLE patients.

Th1/Th2 cytokine profile in childhood-onset systemic lupus erythematosus

OBJECTIVE

To determine the serum levels of Th1 (IL-12, IFN-γ,TNF-α) and Th2 (IL-5, IL-6 and IL-10) cytokines in childhood-onset SLE, first-degree relatives and healthy controls. To elucidate their association with disease activity, laboratory and treatment features.

METHODS

We included 60 consecutive childhood-onset SLE patients [median age 18 years (range 10-37)], 64 first-degree relatives [median 40 (range 28-52)] and 57 healthy [median age 19 years (range 6-30 years)] controls. Controls were age and sex-matched to SLE patients. SLE patients were assessed for clinical and laboratory SLE manifestations, disease activity (SLEDAI), damage (SDI) and current drug exposures. Mood and anxiety disorders were determined through Becks Depression (BDI) and Anxiety Inventory (BAI). Th1 (IL-12, IFN-γ,TNF-α) and Th2 (IL-5, IL-6 and IL-10) cytokines levels were measured by ELISA and compared by non-parametric tests.

RESULTS

Serum TNF-α (p=0.004), IL-6 (p=0.007) and IL-10 (p=0.03) levels were increased in childhood-onset SLE patients when compared to first-degree relatives and healthy controls. TNF-α levels were significantly increased in patients with active disease (p=0.014) and correlated directly with SLEDAI scores (r=0.39; p=0.002). IL-12 (p=0.042) and TNF-α (p=0.009) levels were significantly increased in patients with nephritis and TNF-α in patients with depression (p=0.001). No association between cytokine levels and SDI scores or medication was observed.

CONCLUSION

Th1 cytokines may play a role in the pathogenesis of neuropsychiatric and renal manifestations in childhood-onset SLE. The correlation with SLEDAI suggests that TNF-α may be a useful biomarker for disease activity in childhood-onset SLE, however longitudinal studies are necessary to determine if increase of this cytokine may predict flares in childhood-onset SLE.

The role of Tumor Necrosis Factor-alpha (TNF-α) in the pathogenesis of systemic lupus erythematosus

The Tumor Necrosis Factor-alpha (TNF-α) is a pleiotropic cytokine that produces different stimuli in various physiological and pathological conditions. TNF-α contributes importantly to the development of T cells, B cells, and dendritic cells. However, TNF-α is also a potent inflammatory mediator and apoptosis inducer. The significance of the TNF-α involvement in the pathogenesis of systemic lupus erythematosus (SLE) remains controversial. From the genetic standpoint, a number of studies suggest that the TNF-α gene polymorphism is involved in the susceptibility of SLE. Moreover, there is a close association between the TNF-α gene expression and clinical manifestations. In addition, the increased serum level of TNF-α is observed in SLE patients and associated with disease activity and certain systemic manifestations. Treatment with anti-TNF agents is, however, controversial in SLE since induction of antinuclear antibodies, anti-dsDNA, anticardiolipin antibodies, and cases of drug-induced lupus have been observed in rheumatoid arthritis patients. In this context, this study reviewed the importance of TNF-α in the pathogenesis of SLE.

TNFA2 and d2 alleles of the tumor necrosis factor alpha gene polymorphism are associated with onset/occurrence of idiopathic membranous nephropathy

Idiopathic membranous nephropathy (IMN) has a strong association with the major histocompatibility complex HLA B8DR3(17)DQ2 haplotype. The tumor necrosis factor (TNF)A gene is located within the major histocompatibility complex region on chromosome 6. We have studied the influence of two functional polymorphisms; the -308 (promoter region) and the TNFd microsatellites on initiation and/or progression of IMN. This was a case-control study comparing data from 100 Caucasians patients (67 male subjects; 67%) with IMN to 232 Caucasians local controls (171 male subjects; 74%). We have analyzed genotypes and alleles distributions and the role of these polymorphisms in disease progression towards end-stage renal failure or patient death. For -308 TNFA polymorphism, distribution of genotypes was significantly different between IMN and controls (chi(2)=16.25; P=0.0003): the A2 allele frequency was 28.0% in IMN vs 15.3% in controls (chi(2)=14.57; P=0.0001). For TNFd polymorphism, alleles distribution (from d1 to d7) was also significantly different between IMN and controls (chi(2)=56.74; P<0.0001) with both diminished d3 allele frequency (chi(2)=27.30; P<0.0001; Pc=0.001) and increased d2 allele frequency (chi(2)=29.95; P<0.0001; Pc=0.001) in IMN. We could not isolate any significant and independent influence of these different genotypes on IMN disease progression. The TNFA2 and TNFd2 alleles were strongly associated with occurrence/initiation of IMN and should be considered as susceptibility genes for this disease.

Serum monocyte chemoattractant protein-1 and monocyte adhesion molecules in type 1 diabetic patients with nephropathy

BACKGROUND

Monocyte chemoattractant protein (MCP)-1 is suggested to be implicated in the pathogenesis of diabetic nephropathy by activating and recruiting monocytes to the glomerulus via regulation of adhesion molecule expressions. The aim of this study was to test potential associations between serum concentrations of MCP-1, monocyte expression of Mac-1 and LFA-1 and nephropathy in type 1 diabetes mellitus.

METHODS

Serum MCP-1 levels and expression of monocyte adhesion molecules in 51 type 1 diabetic patients with and without diabetic nephropathy were compared with matched 15 healthy control subjects. Concentrations of serum MCP-1 were determined by enzyme-linked immunosorbent assays whereas monocyte expression of adhesion molecules Mac-1 and LFA-1 was measured by flow cytometry.

RESULTS

Serum MCP-1 levels and expression of Mac-1, but not LFA-1, were significantly higher in diabetic patients compared with controls. The mean serum MCP-1 level was 137.2 +/- 71.4 pg/mL in control patients, whereas it was 246.2 +/- 114.9 pg/ml in diabetic patients (p = 0.002). Serum MCP-1 levels were positively correlated with HbA1c and plasma fasting glucose levels. There was no difference in serum levels of MCP-1 and expression of monocyte adhesion molecules between type 1 diabetic patients with and without diabetic nephropathy.

CONCLUSIONS

In type 1 diabetic patients, the levels of circulating MCP-1 concentration and expression of Mac-1 is mostly influenced by glycemic control rather than the existence of diabetic nephropathy.