Expression of CD39 by human peripheral blood CD4+ CD25+ T cells denotes a regulatory memory phenotype.

We have shown that CD39 and CD73 are coexpressed on the surface of murine CD4+ Foxp3+ regulatory T cells (Treg) and generate extracellular adenosine, contributing to Treg immunosuppressive activity. We now describe that CD39, independently of CD73, is expressed by a subset of blood-derived human CD4+ CD25+ CD127lo Treg, defined by robust expression of Foxp3. A further distinct population of CD4+ CD39+ T lymphocytes can be identified, which do not express CD25 and FoxP3 and exhibit the memory effector cellular phenotype. Differential expression of CD25 and CD39 on circulating CD4+ T cells distinguishes between Treg and pathogenic cellular populations that secrete proinflammatory cytokines such as IFNγ and IL-17. These latter cell populations are increased, with a concomitant decrease in the CD4+ CD25+ CD39+ Tregs, in the peripheral blood of patients with renal allograft rejection. We conclude that the ectonucleotidase CD39 is a useful and dynamic lymphocytes surface marker that can be used to identify different peripheral blood T cell-populations to allow tracking of these in health and disease, as in renal allograft rejection.

Variations in the complement regulatory genes factor H (CFH) and factor H related 5 (CFHR5) are associated with membranoproliferative glomerulonephritis type II (dense deposit disease).

INTRODUCTION: Membranoproliferative glomerulonephritis type II or dense deposit disease (MPGN II/DDD) causes chronic renal dysfunction that progresses to end stage renal disease in about half of patients within 10 years of diagnosis. Deficiency of and mutations in the complement factor H (CFH) gene are associated with the development of MPGN II/DDD, suggesting that dysregulation of the alternative pathway of the complement cascade is important in disease pathophysiology. SUBJECTS: Patients with MPGN II/DDD were studied to determine whether specific allele variants of CFH and CFHR5 segregate preferentially with the MPGN II/DDD disease phenotype. The control group was compromised of 131 people in whom age related macular degeneration had been excluded. RESULTS: Allele frequencies of four single nucleotide polymorphisms in CFH and three in CFHR5 were significantly different between MPGN II/DDD patients and controls. CONCLUSION: We have identified specific allele variants of CFH and CFHR5 associated with the MPGN II/DDD disease phenotype. While our data can be interpreted to further implicate complement in the pathogenesis of MPGN II/DDD, these associations could also be unrelated to disease pathophysiology. Functional studies are required to resolve this question.

A1 beta-casein milk protein and other environmental pre-disposing factors for type 1 diabetes.

Globally type 1 diabetes incidence is increasing. It is widely accepted that the pathophysiology of type 1 diabetes is influenced by environmental factors in people with specific human leukocyte antigen haplotypes. We propose that a complex interplay between dietary triggers, permissive gut factors and potentially other influencing factors underpins disease progression. We present evidence that A1 ß-casein cows' milk protein is a primary causal trigger of type 1 diabetes in individuals with genetic risk factors. Permissive gut factors (for example, aberrant mucosal immunity), intervene by impacting the gut's environment and the mucosal barrier. Various influencing factors (for example, breastfeeding duration, exposure to other dietary triggers and vitamin D) modify the impact of triggers and permissive gut factors on disease. The power of the dominant trigger and permissive gut factors on disease is influenced by timing, magnitude and/or duration of exposure. Within this framework, removal of a dominant dietary trigger may profoundly affect type 1 diabetes incidence. We present epidemiological, animal-based, in vitro and theoretical evidence for A1 ß-casein and its ß-casomorphin-7 derivative as dominant causal triggers of type 1 diabetes. The effects of ordinary milk containing A1 and A2 ß-casein and milk containing only the A2 ß-casein warrant comparison in prospective trials.

Sublytic complement injury does not activate NF-kappa B, or induce mitogenesis in rat mesangial cells.

Sublytic complement injury to glomerular mesangial cells, mediated by the terminal membrane attack complex of complement (C5b-9), is a potential initiating mechanism in IgA nephropathy. Sublytic complement injury has been reported to result in the production of a variety of pro-inflammatory molecules and growth factors, including many regulated by the transcription factor NF-kappa B. To determine the importance of complement injury in the pro-inflammatory signalling which occurs in IgA nephropathy, we investigated NF-kappa B activation following sublytic complement injury to cultured rat glomerular mesangial cells (RMCs). A sublytic dose of rabbit anti-Thy 1.1 (THY) serum and normal human serum was selected based upon flow cytometry, chromium-release assay, and induction of superoxide production. No significant C5b-9-induced NF-kappa B activation was detected by electrophoretic mobility shift assays, luciferase activity of RMCs transfected with a NF-kappa B-driven luciferase reporter construct, nor by Northern blots for the NF-kappa B-responsive mRNA species monocyte chemoattractant protein-1 or I kappa B alpha. Furthermore, measurements of (3)H incorporation following sublytic complement injury showed inhibition of mesangial cell mitogenesis in comparison to the heat-inactivated serum treatment and to THY alone. The results of this study suggest that sublytic complement injury to RMC does not directly activate NF-kappa B nor induce mesangial cell proliferation in mesangial cells. Other mechanisms such as IgA immune complex formation must be required to produce these events in IgA nephropathy.

Clusterin depletion enhances immune glomerular injury in the isolated perfused kidney.

Clusterin is a normal plasma protein, shown to be an inhibitor of reactive complement hemolysis and a component of the fluid phase SC5b-9 terminal complement complexes. It is a component of glomerular immune deposits in human and experimental glomerulonephritis. Using the complement-dependent isolated perfused rat kidney model of autologous phase passive Heymann nephritis, we have studied the effect of clusterin depletion of perfused plasma on the development of glomerular injury. Kidneys with planted glomerular sheep anti-rat Fx1A antibody were perfused with human plasma either depleted of clusterin to < or = 30%, or control plasma depleted of plasma fibronectin. Glomerular injury was then initiated by the addition of guinea pig anti-sheep immunoglobulins to the perfusate. Kidneys perfused with clusterin depleted plasma developed significantly greater proteinuria at all time points when compared to control kidneys. Glomerular antibody binding and C3 deposition were similar in the two groups, but terminal complement components were deposited in larger amounts in the clusterin depleted group. These data support a possible role for clusterin in vivo in the protection of complement-induced glomerular injury.

Human factor H-related protein 5 (FHR-5). A new complement-associated protein.

A novel human plasma protein has been identified as a universal component of complement deposits, when complement is detected immunohistochemically in vivo. The protein is homologous to complement factor H and related proteins and has been designated factor H-related protein 5 (FHR-5). FHR-5 was identified by a monoclonal antibody raised using pathologic human glomerular preparations as the immunogen. FHR-5 was purified by affinity chromatography from complement-lysed erythrocytes, and the peptide sequence was obtained. The cDNA was cloned from a human liver library, and FHR-5 was deduced to be a protein containing 551 amino acids organized into nine short consensus repeat motifs. The short consensus repeats of FHR-5 show homology to Factor H and to other Factor H-related proteins, with some unique features demonstrated. Recombinant FHR-5, expressed in insect cells, was shown to bind C3b in vitro. The strong association of FHR-5 with tissue complement deposits in vivo suggests that this additional member of the Factor H family of proteins has a function in complement regulation.