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Biomedical subjects

Paul Cockwell

Publications and source records attributed to Paul Cockwell.

11 recordsLinked to original sources
PubMed2007

Efficient removal of immunoglobulin free light chains by hemodialysis for multiple myeloma: in vitro and in vivo studies.

Of patients with newly diagnosed multiple myeloma, approximately 10% have dialysis-dependent acute renal failure, with cast nephropathy, caused by monoclonal free light chains (FLC). Of these, 80 to 90% require long-term renal replacement therapy. Early treatment by plasma exchange reduces serum FLC concentrations, but randomized, controlled trials have shown no evidence of renal recovery. This outcome can be explained by the low efficiency of the procedure. A model of FLC production, distribution, and metabolism in patients with myeloma indicated that plasma exchange might remove only 25% of the total amount during a 3-wk period. For increasing FLC removal, extended hemodialysis with a protein-leaking dialyzer was used. In vitro studies indicated that the Gambro HCO 1100 dialyzer was the most efficient of seven tested. Model calculations suggested that it might remove 90% of FLC during 3 wk. This dialyzer then was evaluated in eight patients with myeloma and renal failure. Serum FLC reduced by 35 to 70% within 2 hr, but reduction rates slowed as extravascular re-equilibration occurred. FLC concentrations rebounded on successive days unless chemotherapy was effective. Five additional patients with acute renal failure that was caused by cast nephropathy then were treated aggressively, and three became dialysis independent. A total of 1.7 kg of FLC was removed from one patient during 6 wk. Extended hemodialysis with the Gambro HCO 1100 dialyzer allowed continuous, safe removal of FLC in large amounts. Proof of clinical value now will require larger studies.

Acute Kidney Injury↗
PubMed2006

ABO-incompatible live donor renal transplantation using blood group A/B carbohydrate antigen immunoadsorption and anti-CD20 antibody treatment.

BACKGROUND: Blood group ABO-incompatible live donor (LD) renal transplantation may provide a significant source of organs. We report the results of our first 14 cases of ABO-incompatible LD renal transplantation using specific anti-A/B antibody (Ab) immunoadsorption (IA) and anti-CD20 monoclonal Ab (mAb) treatment. PATIENTS AND TREATMENT PROTOCOL: Recipients were blood group O (n = 12), A (n = 1) and B (n = 1). Donors were A1 (n = 2), A2 (n = 3), A2B (n = 1) and B (n = 8), and all were secretor positive. Anti-human leukocyte antigen (HLA) Ab panel reactivity was negative in all recipients except one. All recipients were pre-treated with 3 to 6 IA sessions, using A or B carbohydrate antigen columns, until their anti-A1/B RBC panel indirect antiglobulin test (IAT) titers were < or =8. CDC crossmatch was negative in all cases. Recipients received preoperative mycophenolic acid, and steroids/tacrolimus were started at transplantation. No splenectomy was performed. Eight recipients received one dose of anti-CD20 mAb (rituximab, 375 mg/m2) pre-operatively and 11 recipients had postoperative protocol IA. RESULTS: In the initial protocol, anti-CD20 mAbs were used only for recipients receiving A1 grafts. One B graft (HLA-identical donor, 84% panel reactivity) was lost in a severe anti-B Ab-mediated acute rejection. Subsequently, the protocol included anti-CD20 for recipients of both A1 and B grafts and postoperative protocol IA to all recipients. The subsequent 10 grafts had excellent function, giving a total graft survival of 13/14 (observation range 2 to 41 months). At 1 yr, mean serum creatinine was 113 micromol/l (n = 8) and mean glomerular filtration rate was 55 ml/min/1.73 m2 (range 24 to 77). In the remaining five cases, with less than 1 yr follow up, mean serum creatinine was 145 micromol/l at 2 to 9 months follow up. Pre-IA anti-A/B titers were in the range of 2 to 32 (NaCl technique) and 16 to 512 (IAT). More than 90 IA sessions were performed in 14 recipients without any significant side effects. Recipient anti-A/B titers returned after transplantation to pre-IA levels or slightly lower. Postoperative renal biopsies were performed in 10 patients. In the 13 patients with long-term function, one patient experienced cellular rejection (Banff IIB) at 3 months without anti-B titer rise. This rejection was concomitant with low tacrolimus plasma levels and was easily reversed by steroids. In 8 of 10 cases, C4d staining was positive in peritubular capillaries. CONCLUSION: Blood group ABO-incompatible LD renal transplantation using A and B carbohydrate-specific IA and anti-CD20 mAbs has excellent graft survival and function.

ABO Blood-Group System↗
PubMed2005

Increased expression of mineralocorticoid effector mechanisms in kidney biopsies of patients with heavy proteinuria.

BACKGROUND: Aldosterone has emerged as a deleterious hormone in the heart, with mineralocorticoid receptor (MR) blockade reducing mortality in patients with severe heart failure. There is also experimental evidence that aldosterone contributes to the development of nephrosclerosis and renal fibrosis in rodent models, but little is known of its role in clinical renal disease. METHODS AND RESULTS: We quantified MR, serum- and glucocorticoid-regulated kinase 1 (sgk1), and mRNA expression of inflammatory mediators such as macrophage chemoattractant protein-1 (MCP-1), transforming growth factor-beta1, and interleukin-6 in 95 human kidney biopsies in patients with renal failure and mild to marked proteinuria of diverse etiologic origins. We measured renal function, serum aldosterone, urinary MCP-1 protein excretion, and the amount of chronic renal damage. Macrophage invasion was quantified by CD68 and vascularization by CD34 immunostaining. Serum aldosterone correlated negatively with creatinine clearance (P<0.01) and positively with renal scarring (P<0.05) but did not correlate with MR mRNA expression or proteinuria. Patients with heavy albuminuria (>2 g/24 h; n=15) had the most renal scarring and the lowest endothelial CD34 staining. This group showed a significant 5-fold increase in MR, a 2.5-fold increase in sgk1 expression and a significant increase in inflammatory mediators (7-fold increase in MCP-1, 3-fold increase in transforming growth factor-beta1, and 2-fold increase in interleukin-6 mRNA). Urinary MCP-1 protein excretion and renal macrophage invasion were significantly increased in patients with heavy albuminuria. CONCLUSIONS: These studies support animal data linking aldosterone/MR activation to renal inflammation and proteinuria. Further studies are urgently required to assess the potential beneficial effects of MR antagonism in patients with renal disease.

Adolescent↗
PubMed2005

Macrophages and progressive tubulointerstitial disease.

Macrophages and progressive tubulointerstitial disease. In chronic renal disease, tubulointerstitial inflammation and injury is associated with infiltrating macrophages. As a consequence of primary injury, proteinuria, chronic hypoxia, and glomerular-derived cytokines may all differentially modulate the expression of factors that promote macrophage recruitment. In addition to adhesion molecules and chemokines, products of complement system and renin-angiotensin system activation may direct this process. Once present at interstitial sites, macrophages interact with resident cells and extracellular matrix to generate a proinflammatory microenvironment that amplifies tissues injury and promotes scarring. There is now increasing evidence for the efficacy of interventions directed against factors that recruit, activate, or are produced by macrophages. A detailed understanding of the biology of this area may lead to the further development of therapies that will improve the outcome of renal disease.

Humans↗
PubMed2005

Expression of renal 11beta-hydroxysteroid dehydrogenase type 2 is decreased in patients with impaired renal function.

OBJECTIVE: Renal 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) enables selective access of aldosterone to the mineralocorticoid receptor (MR). Impaired 11beta-HSD2 activity has been suggested in patients with hypertension as well as in patients with renal disease, where it may contribute to sodium retention, oedema and hypertension. To date, these studies have relied upon urinary cortisol (F) metabolite levels as surrogate markers of renal 11beta-HSD2 activity. METHODS: We have directly analysed renal 11beta-HSD2 mRNA expression in 95 patients undergoing kidney biopsy using TaqMan real-time PCR. Serum and 24-h urine samples were used to document underlying renal function and endocrine parameters. Urinary F and cortisone (E) metabolites were analysed using gas chromatography/mass spectrometry. RESULTS: Expression of 11beta-HSD2 did not correlate with blood pressure or urinary Na/K ratio, but a significant positive correlation with creatinine clearance was observed (r = 0.284; P < 0.01). Immunofluorescence and confocal laser microscopy confirmed decreased 11beta-HSD2 expression in patients with impaired renal function. For the first time, we showed that 11beta-HSD2 mRNA expression correlated negatively with the urinary free (UF) F/E (UFF/UFE) ratio (r = 0.276; P < 0.05) as well as with the urinary tetrahydrocortisol + 5alpha-tetrahydrocortisol/tetrahydrocortisone ((THF + alphaTHF)/THE) ratio (r = 0.256; P < 0.05). No difference in 11beta-HSD2 mRNA expression or in the UFF/UFE ratio was found between groups with no proteinuria, microalbuminuria, moderate or severe proteinuria. In contrast, the urinary (THF + alphaTHF)/THE ratio increased significantly (P < 0.05) in patients with severe albuminuria, suggesting increased hepatic 11beta-HSD1 in those patients. CONCLUSIONS: These data suggest that renal 11beta-HSD2 expression may be represented only marginally better, if at all, by the UFF/UFE than by the (THF + alphaTHF)/THE ratio. Reduced renal 11beta-HSD2 expression may lead to occupancy of the MR by glucocorticoids such as cortisol and may contribute to the increased sodium retention seen in patients with impaired renal function.

11-beta-Hydroxysteroid Dehydrogenase Type 2↗
PubMed2003

Interleukin-2 receptor monoclonal antibodies in renal transplantation: meta-analysis of randomised trials.

OBJECTIVE: To study the effect of interleukin-2 receptor monoclonal antibodies on acute rejection episodes, graft loss, deaths, and rate of infection and malignancy in patients with renal transplants. DESIGN: Meta-analysis of published data. DATA SOURCES: Medline, Embase, and Cochrane library for years 1996-2003 plus search of medical editors' trial amnesty and contact with manufacturers of the antibodies. SELECTION OF STUDIES: Randomised controlled trials comparing interleukin-2 receptor antibodies with placebo or no additional treatment in patients with renal transplants receiving ciclosporin based immunosuppression. RESULTS: Eight randomised controlled trials involving 1871 patients met the selection criteria (although only 1858 patients were analysed). Interleukin-2 receptor antibodies significantly reduced the risk of acute rejection (odds ratio 0.51, 95% confidence interval 0.42 to 0.63). There were no significant differences in the rate of graft loss (0.78, 0.58 to 1.04), mortality (0.75, 0.46 to 1.23), overall incidence of infections (0.97, 0.77 to 1.24), incidence of cytomegalovirus infections (0.81, 0.62 to 1.04), or risk of malignancies at one year (0.82, 0.39 to 1.70). The different antibodies had a similar sized effect on acute rejection (test for heterogeneity P=0.7): anti-Tac (0.37, 0.16 to 0.89), BT563 (0.37, 0.1 to 1.38), basiliximab (0.56, 0.44 to 0.72), and daclizumab (0.46, 0.32 to 0.67). The reduction in acute rejections was similar for all ciclosporin based immunosuppression regimens (test for heterogeneity P=1.0). CONCLUSIONS: Adding interleukin-2 receptor antibodies to ciclosporin based immunosuppression reduces episodes of acute rejection at six months by 49%. There is no evidence of an increased risk of infective complications. Longer follow up studies are needed to confirm whether interleukin-2 receptor antibodies improve long term graft and patient survival.

Antibodies, Monoclonal↗
PubMed2002

Fractalkine expression in human renal inflammation.

Immune and inflammatory human renal disease is associated with heavy mononuclear cell infiltration. The trafficking of these cells to extravascular sites is directed by local production of chemokines. Fractalkine is the first described cell-surface anchored chemokine and has potent mononuclear cell-directed adhesion and chemotactic properties. The purpose of this study was to analyse the expression and distribution of fractalkine in human renal inflammation. In situ hybridization and immunohistochemistry were used to study renal biopsies from 15 patients with predominant glomerular inflammation (vasculitic glomerulonephritis) and 15 with predominant tubular and interstitial inflammation (acute renal allograft rejection). Controls comprised non-inflammatory glomerulonephritis and normal tissue. Fractalkine mRNA was predominantly expressed in the major compartment, glomerular or tubulointerstitial, affected by disease and with the strongest expression localized to vascular sites local to inflammation. In acute renal allograft rejection, there was increased expression of fractalkine mRNA by tubular epithelial cells. There was no expression of fractalkine by infiltrating leukocytes and there was only sparse expression in control tissue. Fractalkine mRNA expression correlated with infiltrating leukocyte subsets. Immunohistochemistry confirmed this pattern of expression, with serial section co-localization showing fractalkine expression in areas with macrophage (CD68+) and T cell (CD3+) infiltrates. These expression patterns show that fractalkine is a strong candidate for directing mononuclear cell infiltration in human renal inflammation.

Acute Disease↗
PubMed2002

Mycophenolate mofetil in the treatment of resistant idiopathic nephrotic syndrome.

BACKGROUND: A small proportion of patients with initially steroid-sensitive nephrotic syndrome relapse frequently, despite treatment with cyclophosphamide and/or cyclosporin. We investigated the efficacy of mycophenolate mofetil (MMF) in this group. METHODS: Seven patients with nephrotic syndrome due to minimal change nephropathy (MCN) or classical focal segmental glomerulosclerosis (FSGS) who had suffered multiple relapses over many years despite treatment with several different agents were commenced on MMF 1 g twice daily, together with a reducing dose of corticosteroids. RESULTS: Six patients went into complete remission and the seventh into partial remission. At 1 year, five remained in complete remission. The median (range) serum albumin concentration rose from 19 g/l (16-42 g/l) pre-MMF to 42 g/l (25-45 g/l) after 12 months (P=0.023), and the median (range) dose of prednisolone fell from 40 mg/day (30-60 mg/day) to 7.5 mg/day (0-40 mg/day) at 12 months (P=0.0008). CONCLUSION: MMF appears to be of benefit in the treatment of multiply relapsing nephrotic syndrome caused by MCN or FSGS. Controlled trials are required to establish the role of MMF in these disorders.

Adult↗
PubMed2002

Chemoattraction of T cells expressing CCR5, CXCR3 and CX3CR1 by proximal tubular epithelial cell chemokines.

BACKGROUND: Chemokines produced by resident renal cells promote the infiltration of leukocyte subsets. We have analysed the chemotactic responses of CD3+ peripheral blood lymphocytes (PBLs) to factors secreted by proximal tubular epithelial cells (PTEC), assessing the role of chemokines and chemokine receptors in this process. METHODS: By FACS we analysed expression of the chemokine receptors CCR5, CXCR3, CX3CR1, CCR2, CXCR1 and CXCR2 on both freshly isolated and activated PBLs. Using Boyden chambers we studied the chemotactic activity of supernatant from resting and cytokine-stimulated (TNF-alpha and IFN-gamma) PTEC towards PBLs. Soluble recombinant chemokines and blocking antibodies were used to study the role of individual chemokine receptors. Chemokine secretion by PTEC was analysed by ELISA. RESULTS: Only a small proportion of freshly isolated cells expressed the chemokine receptors and there was low grade chemotaxis of these cells towards cytokine-stimulated PTEC supernatant compared with unstimulated PTEC supernatant. After activation, 84% of PBLs expressed CCR5, 90% expressed CXCR3 and 19% expressed CX3CR1. There remained low expression levels of CXCR1, CXCR2 and CCR2. Activated PBLs showed strong chemotactic responses to supernatant from cytokine-stimulated PTEC compared with unstimulated PTEC (P<0.001). Chemotaxis of these cells was inhibited by blocking CCR5, CXCR3 and CX3CR1 by 69%, 71% and 29% respectively, with complete inhibition following combined blockade. ELISA showed high levels of the chemokine RANTES/CCL5 (for CCR5) and IP-10/CXCL10 (for CXCR3) in cytokine-stimulated PTEC supernatant. CONCLUSIONS: Chemokines produced by cytokine activated PTEC promote the selective recruitment of activated T cells via the receptors, CCR5, CXCR3 and CX3CR1. These receptors may be amenable to therapeutic manipulation in renal inflammation.

Antigens, Surface↗