Acute interstitial nephritis with immune complex deposition and MHC class II antigen presentation along the tubular basement membrane

Impact of endogenous stress on albumin structure in systemic lupus erythematosus (SLE) patients

Systemic lupus erythematosus (SLE) is an inflammatory, autoimmune disorder of unknown etiology. The inflammatory stress in SLE patients may modify macromolecules and produce structural/functional abnormalities. The present study is aimed at examining the consequences of stresses on the structure of albumin in SLE patients. Albumin was isolated from the sera of SLE/healthy subjects. Multiple physicochemical techniques were used to elucidate, structure of albumin. Advanced glycation end products in SLE patients' albumin were identified by the AGE specific fluorescence. Quenching of tryptophan, tyrosine fluorescence and surface protein hydrophobicity was observed in SLE patients' albumin. Protein-bound carbonyls were elevated while free thiol, lysine, arginine, and alpha helicity was found to be decreased in SLE albumin. Furthermore, changes in the secondary structure of SLE albumin were observed as shift in the position of amide I/II bands. Functionality of SLE albumin was also compromised as its cobalt-binding ability was substantially declined. Adduction of moieties was detected by dynamic light scattering (DLS) and confirmed by matrix assisted laser desorption/ionization. DLS, thioflavin T and transmission electron microscopy results confirmed aggregates in SLE patients' albumin. This study may be helpful in understanding the role of modified albumin in the cofounding pathologies associated with SLE.

High mobility group box 1 (HMGB1) and anti-HMGB1 antibodies and their relation to disease characteristics in systemic lupus erythematosus

Introduction

High Mobility Group Box 1 (HMGB1) is a nuclear non-histone protein. HMGB1, which is secreted by inflammatory cells and passively released from apoptotic and necrotic cells, may act as a pro-inflammatory mediator. As apoptotic cells accumulate in systemic lupus erythematosus (SLE), HMGB1 levels might be increased in SLE. HMGB1 may also serve as an autoantigen, leading to the production of anti-HMGB1 antibodies. In this study we determined levels of HMGB1 and anti-HMGB1 in SLE patients in comparison to healthy controls (HC) and analysed their relation with disease activity.

Methods

The study population consisted of 70 SLE patients and 35 age- and sex-matched HC. Thirty-three SLE patients had quiescent disease, the other 37 patients were selected for having active disease. Nineteen of these had lupus nephritis. HMGB1 levels were measured with both Western blot and ELISA. Anti-HMGB1 levels were measured by ELISA. Clinical and serological parameters were assessed according to routine procedures.

Results

HMGB1 levels in SLE patients could be measured reliably by Western blotting only, and were significantly increased compared to HC. During active disease HMGB1 levels increased, in particular in patients with renal involvement. Serum HMGB1 levels correlated with SLEDAI, proteinuria, and anti-dsDNA levels, and showed a negative correlation with complement C3. Anti-HMGB1 levels were significantly increased in SLE patients compared to HC, and positively correlated with HMGB1 levels.

Conclusions

Levels of HMGB1 in the sera of SLE patients, in particular in those with active renal disease, are increased. Serum HMGB1 levels are related to SLEDAI scores and proteinuria, as well as to levels of anti-HMGB1 antibodies. These findings suggest that besides HMGB1, HMGB1-anti-HMGB1 immune complexes play a role in the pathogenesis of SLE, in particular in patients with renal involvement.

Hypocomplementaemic immune complex tubulointerstitial nephritis

We report a rare cause of rapidly progressive renal failure associated with low complement, positive ANA but negative anti DS-DNA. A renal biopsy demonstrated tubulointerstitial nephritis with positive immunoglobulin staining involving the interstitium and tubular basement membrane but glomerular sparing. A review of the literature and differential diagnosis are discussed.

Idiopathic hypocomplementemic immune-complex-mediated tubulointerstitial nephritis

BACKGROUND

A 42-year-old man presenting with flank pain was found to have renal failure with severe hypocomplementemia and eosinophilia.

INVESTIGATIONS

Physical examination, laboratory testing, renal ultrasonography, and renal biopsies.

DIAGNOSIS

Acute immune-complex-mediated tubulointerstitial nephritis.

MANAGEMENT

Immunosuppressive therapy with 1 mg/kg/day prednisone.