Adhesion of Escherichia coli under flow conditions reveals potential novel effects of FimH mutations.

FimH-mediated adhesion of Escherichia coli to bladder epithelium is a prerequisite for urinary tract infections. FimH is also essential for blood-borne bacterial dissemination, but the mechanisms are poorly understood. The purpose of this study was to assess the influence of different FimH mutations on bacterial adhesion using a novel adhesion assay, which models the physiological flow conditions bacteria are exposed to. We introduced 12 different point mutations in the mannose binding pocket of FimH in an E. coli strain expressing type 1 fimbriae only (MSC95-FimH). We compared the bacterial adhesion of each mutant across several commonly used adhesion assays, including agglutination of yeast, adhesion to mono- and tri-mannosylated substrates, and static adhesion to bladder epithelial and endothelial cells. We performed a comparison of these assays to a novel method that we developed to study bacterial adhesion to mammalian cells under flow conditions. We showed that E. coli MSC95-FimH adheres more efficiently to microvascular endothelium than to bladder epithelium, and that only endothelium supports adhesion at physiological shear stress. The results confirmed that mannose binding pocket mutations abrogated adhesion. We demonstrated that FimH residues E50 and T53 are crucial for adhesion under flow conditions. The coating of endothelial cells on biochips and modelling of physiological flow conditions enabled us to identify FimH residues crucial for adhesion. These results provide novel insights into screening methods to determine the effect of FimH mutants and potentially FimH antagonists.

Malignant disease in patients with long-term renal transplants.

The incidence of de novo malignancy was analyzed in 274 renal transplant recipients whose graft had functioned for at least 3 years and who had been followed for 2622 patient-years and individually for up to 29 years. The actuarial incidence and relative risks (RR) of tumor development (compared with National statistics) were calculated. Subgroup analysis was performed according to age, sex, the number of years and type of immunosuppression, and the tumor type. Seventy one tumors occurred in 54 patients. Skin tumors were the most common, followed by lymphoma, renal, bladder, and bronchial carcinoma. The actuarial cumulative risks of tumor development were 18.4% (95% confidence interval [CI] 12.4-24.3%) at 10 years and 49.6% (95% CI 36.3-62.0%) at 20 years. The overall RR of developing a tumor was 6.2 but was higher for men (RR 7.3) than women (RR 4.9). The RR of developing skin cancers, but not other malignancies, increased from 6.6 at 5 years to 20 after > 15 years. There was no evidence that cyclosporine-treated patients had an increased incidence of tumors, indeed the risk may be less in patients treated with cyclosporine and low-dose azathioprine than in those treated with azathioprine and prednisolone alone after more than 5 years.

Renal transplantation following immunoadsorption in highly sensitized recipients.

Five highly sensitized patients, with panel reactivity greater than 80% for 1.75-5 years, were treated by extracorporeal staphylococcal protein-A immunoadsorption, prednisolone, and cyclophosphamide. The five patients underwent treatment of 18-40 (mean 31) liters of plasma, respectively in 4-7 (mean 5.6) sessions. This reduced the titer of cytotoxic antibodies to sensitizing antigens to < 1/8 in all cases and abolished reactivity to crossreacting antigens. Two patients required retreatment following resynthesis of cytotoxic antibodies. All five patients have been transplanted, and four of these now have stable serum creatinines of 168 mumol/L at 34 months, 208 mumol/L at 29 months, 96 mumol/L at 5 months, and 125 mumol/L at 3 months posttransplantation. One patient had primary graft dysfunction due to acute tubular necrosis; the kidney was removed after eight weeks and showed cortical necrosis without evidence of acute rejection.

Enumeration of lymphocyte populations in whole peripheral blood of patients with antibody-mediated nephritis during treatment with cyclosporin A.

Lymphocyte populations identified by surface markers were enumerated in whole peripheral blood of 3 patients with Goodpasture's syndrome (mediated by anti-glomerular basement membrane antibody) whilst on treatment with cyclosporin A (CSA). The whole blood method, using alkaline phosphatase-labelled reagents, permits precise enumeration of the relative and absolute numbers of lymphocyte subsets in the circulation. Using conventional rabbit and monoclonal mouse anti-human T-cell antibodies, a small decrease in the percentage of T-lymphocytes was noted following the start of CSA treatment. The absolute T-cell count fell, but only to just below normal. There was no marked or consistent effect on the percentages or absolute numbers of B-cells, C3b-receptor or Fc(gamma)-receptor bearing lymphocytes. These results are compatible with a mechanism of immunosuppression by CSA in which there is selective inhibition of a relatively minor subset of T-lymphocytes.

Excretion of metabolites of prostacyclin and thromboxane by rats with nephrotoxic nephritis: effects of interleukin-1.

1. To obtain direct evidence of abnormal eicosanoid biosynthesis in rats injected with anti-glomerular-basement-membrane antibodies (a-GBM), products derived from thromboxane A2 (TXA2) and prostacyclin (PGI2) were measured in 24 h urine collections before and after a-GBM. 2. Administration of a-GBM (9.5 mg) caused albuminuria, decreased creatinine clearance, increased numbers of intra-glomerular neutrophils and increased excretion of TXB2, 2,3-dinor-TXB2 (products of TXA2) and 6-oxo-PGF 1 alpha and 2,3-dinor-6-oxo-PGF 1 alpha (products of PGI2) at 24 h. 3. Interleukin-1 (IL-1 beta; 5 micrograms) alone caused an increase in PGI2 metabolite excretion but had no effect on TXA2 metabolites. It had no effect on creatinine clearance but increased numbers of glomerular neutrophils by approximately 4-5 fold compared to a-GBM. 4. Pretreatment of rats with IL-1 beta before a-GBM synergistically increased albumin excretion but only additively increased eicosanoid excretion. Numbers of intra-glomerular neutrophils and creatinine clearance were unchanged compared to IL-1 beta alone. 5. The cyclo-oxygenase inhibitor, ibuprofen (10 mgkg-1 i.p., twice daily for 4 days) inhibited both serum TXB2 production and urinary prostaglandin excretion. It also caused an almost complete attenuation of albumin excretion. Creatinine clearance and glomerular neutrophils remained unchanged after a-GBM/IL-1 beta. 6. We conclude that the 50% inhibition of thromboxane production induced by ibuprofen does not modify the fall in creatinine clearance of accumulation of neutrophils in the glomerulus caused by the a-GBM. This degree of inhibition of eicosanoid production was associated with a striking decrease in proteinuria, but this may reflect a haemodynamic rather than a disease modifying action.

Association of immunoglobulin Gm allotypes with antiglomerular basement membrane antibodies and their titer.

We studied the immunoglobulin Gm allotypes in 41 patients with glomerular nephritis caused by autoantibodies to glomerular basement membrane (GBM). Gm phenotypes of all 41 patients were attributable to combinations of the 3 Gm haplotypes commonly found in Caucasoid populations; identified by the allotypes Gm 1,21 (ag), Gm 1,2,21 (axg), and Gm 3,5,11 (fb). The incidence of the putative haplotype Gm 1,2,21 (axg) was greatly increased in the patients being present in 22 of 41 (56%) of patients compared to 28 of 167 controls. (Pcor = 1.5 X 10(-5]. The increase in Gm 1,2,21 (axg) was attributable entirely to presumed heterozygotes with the phenotype Gm 1,2,21;3,5,11 (axg;fb), with concomitant decreases in the frequencies of patients with the phenotypes Gm 1,21 (ax) and with Gm 3,5,11 (fb). Heterozygotes at Gm loci had higher titers of anti-GBM antibodies irrespective of the presence of Gm 1,2,21 (axg). Thus genes within or closely linked to the Gm complex in addition to HLA linked genes influence susceptibility to or clinical expression of anti-GBM disease.

Inhibiting inflammatory cytokines.

Acute glomerulonephritis is a common cause of renal dysfunction and ultimately renal failure. The inflammation involved is a tightly regulated response with pro- and anti-inflammatory cytokines playing key roles. Interleukin-1 (IL-1) and tumor necrosis factor (TNF) are the principal pro-inflammatory cytokines produced by intrinsic cells and infiltrating leukocytes. IL-1 and TNF can be directly antagonized using IL-1 receptor antagonist (IL-1ra) or binding proteins such as soluble receptors or antibodies. Alternatively, cytokines with anti-inflammatory properties can be used to decrease IL-1 and TNF synthesis, increase the production of their natural antagonists and deactivate inflammatory cells such as macrophages. This review will focus on these anti-inflammatory cytokines, principally IL-4, IL-6, IL-10 and IL-13, and highlight recent research of their activities in existing models of renal disease. The results of these experiments offer a promising new avenue of treatment.

In vitro production of tumor necrosis factor by monocytes cultured from dialysis patients.

Cellular release of cytokines may be responsible for certain complications of extracorporeal dialysis including the increased susceptibility to infection found in dialysis patients. In order to study this further, we have evaluated the in vitro production of tumor necrosis factor (TNF) by peripheral blood monocytes (PBMC) to stimulation by lipopolysaccharide (LPS) from dialysis patients with end-stage renal failure (ESRF). The patients were subdivided into two groups according to the type of dialysis; those undergoing hemodialysis (HD) (N = 12) and those performing continuous ambulatory peritoneal dialysis (CAPD) (N = 9). Results were compared with those of controls taken from healthy laboratory staff (N = 7). The experiments show that the secretion of TNF by PBMC's in response to LPS is significantly augmented in patients undergoing HD when compared to those on CAPD (81.3 +/- 38.7 U/ml vs. 18.2 + 13.3 U/ml, mean +/- SD, P < 0.001); and controls (81.3 +/- 38.7 U/ml vs. 18.1 +/- 6.6 U/ml, P < 0.001). There was no significant difference between the CAPD group and controls. In vitro monocyte production of TNF fell following a single HD session (81.3 +/- 38.7 U/ml before HD and 50.5 +/- 28.7 U/ml after HD, P < 0.05). We conclude from this study that TNF release from PBMC's in vitro is augmented in patients with chronic renal failure receiving chronic HD but not in a similar group receiving CAPD. Interestingly, TNF release from monocytes collected immediately following a dialysis was suppressed.(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular analysis of HLA class II genes in Goodpasture's disease.

A molecular analysis of HLA class II genes was undertaken in order to characterize the previously reported association between HLA-DR2 and glomerulonephritis caused by antibodies to glomerular basement membrane (Goodpasture's disease). Genomic DNA was prepared from 53 patients with Goodpasture's disease and analysed by: (i) Southern blotting using cDNA probes to DRB, DQA and DQB genes, after digestion with TaqI endonuclease; (ii) allele-specific oligonucleotide probing of specifically amplified DNA; and (iii) nucleotide sequencing of relevant alleles. The patients had a greatly increased frequency of DRw15 (a subspecificity of DR2) which was present in 75.5% of patients and 31% of controls (p < 0.0001). The frequency of DR4 was also increased, especially in patients without DRw15. Overall, 90.5% of the patients had either DRw15 or DR4. In contrast, the frequency of DR1 was significantly reduced (patients 5.6%, controls 20.7%, p < 0.01). Differences in the frequencies of DQA and DQB alleles could all be explained by linkage disequilibrium. Nucleotide sequences of relevant alleles were identical to those previously published. Comparison of derived amino acid sequences of expressed DR beta chains showed that the DR beta chains of DRw15 and DR4 shared a six-amino-acid motif from positions 26-31, that included four polymorphic amino acids none of which are shared with DR1. A sequence-specific oligonucleotide detected this amino-acid motif in 45/49 (91.8%) patients tested. Thus, this particular motif, which lies on the floor of the antigen binding groove, has a stronger association with Goodpasture's disease than any individual allele, and may be of pathogenic significance.

High incidence of end-stage renal disease in Indo-Asians in the UK.

In a retrospective survey, we show that the incidence of end-stage renal disease (ESRD) is significantly raised among immigrant Indo-Asians referred to two UK renal units (p < 0.001). In addition to the expected increase in diabetic nephropathy, glomerulonephritis and chronic pyelonephritis are also seen more frequently in Indo-Asians. The most striking finding was a five-fold increase in ESRD of uncertain cause (p < 0.001) presenting with small smooth kidneys, which was strongly associated with active, mostly non-renal tuberculosis. The causes of this generalized increased susceptibility to renal disease are unknown. These findings have important implications both for primary health care screening and for planning the provision of renal replacement therapy.

A prospective randomized controlled trial of perioperative antibiotic prophylaxis in renal transplantation.

We have carried out a prospective, randomized controlled trial of perioperative prophylaxis with cefuroxime and piperacillin in 53 recipients of renal allografts. Twenty-seven patients received antibiotic prophylaxis with three doses of cefuroxime 750 mg and piperacillin 4 g, and 26 patients received no prophylaxis. Risk factors for infection were well matched. Infection rates were analysed for the periods 0-5 days and 0-14 days post-transplant. In the first 5 days, patients receiving antibiotics had fewer infections (3 vs. 11, P = 0.04) but by 14 days this difference was no longer apparent (21 vs. 30, P = NS). There was a total of 15 wound infections, which were more common in the control group both at 5 days (1 vs. 5, P = NS) and at 14 days (4 vs. 11, P = 0.027). Urinary infections were unaffected by prophylaxis. We conclude that perioperative antibiotic prophylaxis results in a modest but worthwhile reduction in the incidence of wound infections after renal transplantation.

New approaches to modify glomerular inflammation.

Glomerulonephritis remains the leading cause of end-stage renal failure and treatments for these conditions remain non-specific and with significant side effects. The cellular and molecular basis of acute and chronic inflammation is increasingly understood and the work in a number of animal models of nephritis demonstrates the potential of specific molecular interventions. These include preventing the migration of inflammatory cells by inhibiting the effects of chemokines or blocking endothelial/leucocyte adhesion interactions. Within damaged tissue it is possible to decrease the activity of pro-inflammatory cytokines, such as interleukin-1 (IL-1) and tumour necrosis factor (TNF) by using their natural antagonists, namely interleukin-1 receptor antagonist (IL-1ra) and soluble TNF receptors. In addition the behaviour of macrophages can be altered by the effects of anti-inflammatory cytokines including interleukin-4 (IL-4), interleukin-13 (IL-13), interleukin-10 (IL-10), interleukin-6 (IL-6) and transforming growth factor-beta (TGF-beta). By deactivating the inflammatory response of macrophages these cytokines can favour resolution of disease. The ability to use these approaches in clinical practice remains elusive, however the prospect of using gene transfer technology to deliver anti-inflammatory factors directly to the site of inflammation and our increasing understanding of the complexity of the control of inflammation bring such therapies closer.

Rapidly progressive glomerulonephritis.

The management of rapidly progressive glomerulonephritis has been transformed over the past thirty years. It has become one of the few forms of glomerulonephritis that can be effectively treated, and today overall renal survival is as high as 70%. Effective management of patients with RPGN requires prompt and accurate diagnosis so that patients are appropriately treated, and long term follow up to minimise the risk of relapse in patients with some types of those disease.

Objective monitoring of activity in Wegener's granulomatosis by measurement of serum C-reactive protein concentration.

Serial measurements of the serum concentration of C-reactive protein were made in 38 patients with Wegener's granulomatosis during a period of 6 years. The concentration was always elevated when the disease was active, even in patients receiving immunosuppressive treatment, and fell rapidly in association with clinical remission induced by immunosuppression. During periods of complete remission, in the absence of any intercurrent condition, the value remained within the normal range. The correlation between C-reactive protein level and disease activity was much closer than that between erythrocyte sedimentation rate and disease activity. These results indicate that serial measurement of the serum C-reactive protein fills the urgent need for an objective index of the activity of Wegener's granulomatosis and its response to therapy.

Significance of autoantibodies to purified proteinase 3 in systemic vasculitis.

Proteinase 3 was purified from human neutrophils and used in ELISA to examine sera from 150 patients with systemic vasculitis. It was found to be the major target of autoantibodies in Wegener's granulomatosis, and anti-proteinase 3 antibodies were also found in some patients with microscopic polyarteritis. Anti-proteinase 3 antibodies were associated with a chronic relapsing course.

Relationship between disease activity and ANCA level by ELISA in the long-term management of vasculitis.

Solid-phase immunoassays were used to examine the relationship between ANCA concentration and disease activity during follow-up of 63 patients with systemic vasculitis. ANCA levels fell with induction therapy. Relapses during long-term follow-up were generally associated with high or rising ANCA concentrations, although the temporal relationship between clinical relapse and changes in ANCA was variable.

Towards a more rapid diagnosis of rapidly progressive glomerulonephritis.

An attempt was made to provide simple practical guidelines to alert general practitioners to the diagnosis of rapidly progressive glomerulonephritis and lead to early referral to hospital. The duration of illness before referral to this hospital and its effect on outcome in patients with crescentic nephritis were assessed retrospectively from the case notes of 24 patients referred over two years. Four patients had Goodpasture's syndrome, 11 Wegener's granulomatosis, seven microscopic polyarteritis, and two idiopathic progressive glomerulonephritis. The duration of symptoms before referral to the local hospital was similar in the four groups of patients and varied from one week to 28 months (mean 10 months). The duration of stay in the local hospital was two, nine, 11, and 180 days in the patients with Goodpasture's syndrome and a mean of four days (range one to eight) in those with Wegener's granulomatosis and 10 days (one to 18 days) in those with microscopic polyarteritis. In the local hospital the diagnosis was based on the results of renal biopsy and detection of antibodies to glomerular basement membrane in two patients with Goodpasture's syndrome and on the results of renal biopsy in seven of the other patients aided by the detection of antibodies to the cytoplasm of neutrophils (ANCA) in 10. Three of the 24 patients died and four required maintenance haemodialysis. Patients who present to their general practitioners with persistent non-specific symptoms should have a urine dipstick test and then blood tests and emergency referral to hospital if necessary. Hospital physicians should be aware of the speed and accuracy with which current assays can confirm a diagnosis of rapidly progressive glomerulonephritis.