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Tang Z, Lu B, Hatch E, Sacks SH, Sheerin NS. C3a mediates epithelial-to-mesenchymal transition in proteinuric nephropathy. J Am Soc Nephrol 2009; 20:593-603. [PMID: 19158354 DOI: 10.1681/asn.2008040434] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Tubulointerstitial inflammation and progressive fibrosis are common pathways that lead to kidney failure in proteinuric nephropathies. Activation of the complement system has been implicated in the development of tubulointerstitial injury in clinical and animal studies, but the mechanism by which complement induces kidney injury is not fully understood. Here, we studied the effect of complement on the phenotype of tubular epithelial cells. Tubular epithelial cells exposed to serum proteins adopted phenotypic and functional characteristics of mesenchymal cells. Expression of E-cadherin protein decreased and expression of both alpha-smooth muscle actin protein and collagen I mRNA increased. Exposure of the cells to the complement anaphylotoxin C3a induced similar features. Treating with a C3a receptor (C3aR) antagonist prevented both C3a- and serum-induced epithelial-to-mesenchymal transition. In the adriamycin-induced proteinuria model, C3aR-deficient mice demonstrated less injury, preserved renal function, and improved survival compared with wild-type mice. Furthermore, the kidneys of C3aR-deficient mice had significantly less interstitial collagen I and alpha-smooth muscle actin. In summary, the complement anaphylotoxin C3a is an important mediator of glomerular and tubulointerstitial injury and can induce tubular epithelial-to-mesenchymal transition.
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Greenlaw RE, Gardner NJ, Farrar CA, Shariff H, Sacks SH, Yagita H, Simpson E, Jurcevic S. An antibody combination that targets activated T cells extends graft survival in sensitized recipients. Am J Transplant 2008; 8:2272-82. [PMID: 18785958 DOI: 10.1111/j.1600-6143.2008.02393.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Memory T cells are the very essence of adaptive immunity with their rapid and efficient response to antigen rechallenge and long-term persistence. However, it is becoming increasingly evident that when primed with self or transplanted tissue, these cells play a key role in causing and perpetuating tissue damage. Furthermore, current treatments, which efficiently control the naive response, have limited effects on primed T cells. We have used a treatment based on a combination of antibodies specific for molecules expressed by activated T lymphocytes to selectively remove these cells. This approach, which we termed multi-hit therapy, leads to cumulative binding of antibodies to the target T cells and a striking prolongation of skin graft survival in presensitized recipients in a stringent skin transplant model. The findings are consistent with the depletion of graft-specific CD4+ and CD8+ T cells, although other modes of action, such as T-cell regulation and altered migration could play a role. In conclusion, our therapeutic strategy controls primed T cells which are a major driving force in the pathology of many autoimmune diseases and in transplant rejection.
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Brown K, Sacks SH, Wong W. Extensive and bidirectional transfer of major histocompatibility complex class II molecules between donor and recipient cells in vivo following solid organ transplantation. FASEB J 2008; 22:3776-84. [PMID: 18632850 DOI: 10.1096/fj.08-107441] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Intercellular transfer of surface molecules has been demonstrated in vitro, or in vivo under artificial situations. Transplantation is a unique clinical situation in which foreign major histocompatibility complex (MHC) molecules are deliberately introduced. This provides a model to study intercellular MHC transfer because donor MHC molecules can easily be tracked. Here we describe the bidirectional transfer of MHC class II molecules between donor and recipient cells after transplantation of vascularized kidney and cardiac allografts in mice. Cells that are positive for both donor and recipient MHC class II accounted for up to 30% of the donor MHC class II(+) population, suggesting that they play a significant role in the antigen presentation process. The majority of these cells were dendritic cells, but macrophages and B cells were also able to acquire foreign MHC molecules. Most double-positive cells were also positive for costimulatory molecules, indicating a capability to elicit a T-cell response. This transfer of MHC molecules between donor and recipient cells provides a link between the direct and indirect pathways of alloantigen presentation and suggests that MHC transfer is also likely to occur under normal physiological conditions, which has implications in the fields of infection, vaccination, and tumor immunology.
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Moxham VF, Karegli J, Phillips RE, Brown KL, Tapmeier TT, Hangartner R, Sacks SH, Wong W. Homeostatic Proliferation of Lymphocytes Results in Augmented Memory-Like Function and Accelerated Allograft Rejection. THE JOURNAL OF IMMUNOLOGY 2008; 180:3910-8. [DOI: 10.4049/jimmunol.180.6.3910] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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Rose KL, Paixao-Cavalcante D, Fish J, Manderson AP, Malik TH, Bygrave AE, Lin T, Sacks SH, Walport MJ, Cook HT, Botto M, Pickering MC. Factor I is required for the development of membranoproliferative glomerulonephritis in factor H-deficient mice. J Clin Invest 2008; 118:608-18. [PMID: 18202746 PMCID: PMC2200299 DOI: 10.1172/jci32525] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2007] [Accepted: 11/28/2007] [Indexed: 12/17/2022] Open
Abstract
The inflammatory kidney disease membranoproliferative glomerulonephritis type II (MPGN2) is associated with dysregulation of the alternative pathway of complement activation. MPGN2 is characterized by the presence of complement C3 along the glomerular basement membrane (GBM). Spontaneous activation of C3 through the alternative pathway is regulated by 2 plasma proteins, factor H and factor I. Deficiency of either of these regulators results in uncontrolled C3 activation, although the breakdown of activated C3 is dependent on factor I. Deficiency of factor H, but not factor I, is associated with MPGN2 in humans, pigs, and mice. To explain this discordance, mice with single or combined deficiencies of these factors were studied. MPGN2 did not develop in mice with combined factor H and I deficiency or in mice deficient in factor I alone. However, administration of a source of factor I to mice with combined factor H and factor I deficiency triggered both activated C3 fragments in plasma and GBM C3 deposition. Mouse renal transplant studies demonstrated that C3 deposited along the GBM was derived from plasma. Together, these findings provide what we believe to be the first evidence that factor I-mediated generation of activated C3 fragments in the circulation is a critical determinant for the development of MPGN2 associated with factor H deficiency.
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Sheerin NS, Risley P, Abe K, Tang Z, Wong W, Lin T, Sacks SH. Synthesis of complement protein C3 in the kidney is an important mediator of local tissue injury. FASEB J 2007; 22:1065-72. [PMID: 18039928 DOI: 10.1096/fj.07-8719com] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Increased exposure of the tubular epithelium to filtered protein is a proposed mechanism of progressive renal failure associated with glomerular disease, but how this protein overload translates into tubular damage remains unclear. We have examined a model of adriamycin-induced proteinuria to determine the effect of locally synthesized C3, the central proinflammatory protein of the complement cascade. C3-/- kidney isografts placed in wild-type C3+/+ mice were protected from proteinuria-associated complement activation, tubular damage, and progressive renal failure despite the presence of abundant circulating C3. The quantity of urinary protein was unaffected by the absence of C3, and thus the influence of C3 was not explained by alteration in the filtered protein load. These results suggest that local synthesis of complement from renal epithelial cells is a critical mediator of tubular damage in proteinuria-associated renal disease. Our results concur with previous findings of increased synthesis of C3 in human tubular epithelium exposed to high concentrations of protein in vitro. Because progressive renal damage in humans associates with proteinuria regardless of cause, our findings have implications for the pathogenesis and treatment of renal failure from many common causes, immunological and nonimmunological.
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Brown K, Moxham V, Karegli J, Phillips R, Sacks SH, Wong W. Ultra-localization of Foxp3+ T cells within renal allografts shows infiltration of tubules mimicking rejection. THE AMERICAN JOURNAL OF PATHOLOGY 2007; 171:1915-22. [PMID: 17991712 DOI: 10.2353/ajpath.2007.070396] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Kidney transplant recipients are monitored for rejection by measurement of serum creatinine and graft biopsies. Biopsy samples are evaluated according to the Banff classification, which states that infiltration of tubules by mononuclear cells is an indicator of acute rejection. However, regulatory T cells play a crucial role in the overall immune response and are also present within transplanted tissue. We hypothesize that infiltration of mononuclear cells within kidney grafts is not always associated with rejection, especially if a high proportion of this infiltrate is regulatory T cells. Using a life-sustaining mouse kidney transplant model, we found that mononuclear cell tubular infiltration can occur in both rejecting and tolerant grafts. However, tolerant kidney grafts demonstrated a higher and sustained level of Foxp3+ regulatory cells. Importantly, a significant proportion of these cells were found within tubules. In cases in which graft function was normal, these cells were not harmful to the kidney and could be said to be mimicking, rather than causing, rejection.
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Li K, Sacks SH, Sheerin NS. The classical complement pathway plays a critical role in the opsonisation of uropathogenic Escherichia coli. Mol Immunol 2007; 45:954-62. [PMID: 17870166 DOI: 10.1016/j.molimm.2007.07.037] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2007] [Revised: 07/30/2007] [Accepted: 07/31/2007] [Indexed: 10/22/2022]
Abstract
Urinary tract infection due to uropathogenic Escherichia coli is a common clinical problem. The innate immune system and the uroepithelium are critical in defence against infection. The complement system is both part of the innate immune system and influences the interaction between epithelium and pathogen. We have therefore investigated the mechanism by which uropathogenic E. coli activate complement and the potential for this to occur during clinical infection. The classical pathway is responsible for bacterial opsonisation when complement proteins are present at low concentrations. At higher concentrations the alternative pathway predominates but still requires the classical pathway for its initiation. In contrast the mannose binding lectin pathway is not involved. Early classical pathway components are present in the urine during infection and actively contribute to bacterial opsonisation. The classical pathway could be initiated by anti-E. coli antibodies of IgG or IgM subclasses that are present in urine during infection. Additionally immunoglobulin-independent mechanisms, such as direct C1q binding to bacteria, may be involved. In conclusion, uropathogenic E. coli are readily opsonised by complement in a classical pathway dependent manner. This can occur within the urinary tract during the development of clinical infection.
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Smith RA, Koffman G, Chowdhury P, Smith KG, Watson CJ, Nicholson ML, Zhou W, Sacks SH. Membrane-localising complement inhibitors—clinical progress. Mol Immunol 2007. [DOI: 10.1016/j.molimm.2007.06.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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60
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Li K, Sacks SH, Zhou W. The relative importance of local and systemic complement production in ischaemia, transplantation and other pathologies. Mol Immunol 2007; 44:3866-74. [PMID: 17768105 DOI: 10.1016/j.molimm.2007.06.006] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2007] [Indexed: 10/22/2022]
Abstract
Besides a critical role in innate host defence, complement activation contributes to inflammatory and immunological responses in a number of pathological conditions. Many tissues outside the liver (the primary source of complement) synthesise a variety of complement proteins, either constitutively or response to noxious stimuli. The significance of this local synthesis of complement has become clearer as a result of functional studies. It revealed that local production not only contributes to the systemic pool of complement but also influences local tissue injury and provides a link with the antigen-specific immune response. Extravascular production of complement seems particularly important at locations with poor access to circulating components and at sites of tissue stress responses, notably portals of entry of invasive microbes, such as interstitial spaces and renal tubular epithelial surfaces. Understanding the relative importance of local and systemic complement production at such locations could help to explain the differential involvement of complement in organ-specific pathology and inform the design of complement-based therapy. Here, we will describe the lessons we have learned over the last decade about the local synthesis of complement and its association with inflammatory and immunological diseases, placing emphasis on the role of local synthesis of complement in organ transplantation.
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Rose KL, Paixao-Cavalcante D, Fish J, Manderson AP, Malik T, Bygrave AE, Lin T, Sacks SH, Walport MJ, Cook HT, Botto M, Pickering MC. Factor I is required for the development of membranoproliferative glomerulonephritis in factor H-deficient mice. Mol Immunol 2007. [DOI: 10.1016/j.molimm.2007.06.041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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62
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Peng Q, Li K, Sacks SH, Zhou W. Local C5aR signalling is critical for development of DC function in regulating alloreactive T cell response. Mol Immunol 2007. [DOI: 10.1016/j.molimm.2007.06.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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63
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Brown KM, Sacks SH, Sheerin NS. Mechanisms of disease: the complement system in renal injury--new ways of looking at an old foe. ACTA ACUST UNITED AC 2007; 3:277-86. [PMID: 17457361 DOI: 10.1038/ncpneph0465] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2006] [Accepted: 01/29/2007] [Indexed: 12/12/2022]
Abstract
The fact that the complement system is activated during immune-complex glomerular disease has been known for nearly 50 years. Detection of complement deposition in the glomerulus using immunochemistry has become an important element of the histological analysis of renal biopsies, and is key to the diagnosis of many types of glomerulonephritis. In recent years it has become evident that complement activation is involved in the pathogenesis of other types of renal disease; complement activation is implicated in transplant injury, atypical hemolytic uremic syndrome and progressive tubulointerstitial fibrosis. Emergence of this evidence has provided insight into how these diseases develop, and has yielded useful diagnostic tools and potential targets for therapeutic intervention. Clinicians have, by using plasma-based therapies, unknowingly treated abnormalities of the complement system in renal patients for many years. Advances in antibody and protein technologies have led to the development of complement inhibitors that have been used in phase III clinical studies. More-specific agents and applications are likely to be developed over the coming years and are discussed in this Review.
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Abstract
The innate immune system not only participates in host defence but also contributes to the control of adaptive immune responses. Complement and Toll-like receptors (TLR) are key components of innate immunity. Emerging evidence suggests their activation is involved in all major aspects of transplantation. This paper reviews the current understanding of how the complement and TLR on impact transplant injury.
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Brown HJ, Lock HR, Wolfs TGAM, Buurman WA, Sacks SH, Robson MG. Toll-like receptor 4 ligation on intrinsic renal cells contributes to the induction of antibody-mediated glomerulonephritis via CXCL1 and CXCL2. J Am Soc Nephrol 2007; 18:1732-9. [PMID: 17460147 DOI: 10.1681/asn.2006060634] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Autoimmune diseases such as glomerulonephritis are exacerbated by infection. This study examined the effect of the Toll-like receptor 4 (TLR4) ligand lipid A on the development of heterologous nephrotoxic nephritis. Administration of nephrotoxic antibody resulted in significant glomerular neutrophil infiltration and albuminuria only when a TLR4 ligand was administered simultaneously. The contribution of TLR4 on renal cells and circulating leukocytes was assessed. Bone marrow chimeras were constructed with TLR4 only on renal cells or bone marrow-derived cells. The administration of nephrotoxic serum and lipid A caused a neutrophil influx in both chimeric groups greater than in sham chimeras that were totally TLR4 deficient but significantly less than in sham chimeras that were totally TLR4 sufficient. Both chimeric groups had greater albuminuria than totally TLR4-deficient sham chimeras; however, the chimeras with TLR4 only on intrinsic renal cells had significantly less than the sham positive group. In situ hybridization showed expression of TLR4 mRNA in mesangial cells and glomerular epithelial cells. For investigation of the potential mechanism by which renal cells could contribute to disease exacerbation, mesangial cells were cultured and found to express mRNA for TLR4, and stimulation of wild-type and TLR4-deficient mesangial cells with LPS caused production of CXC chemokines by wild-type cells only. Treatment of chimeras with TLR4 present only on intrinsic renal cells with anti-CXCL1 and anti-CXCL2 antibody before disease induction significantly reduced renal neutrophil infiltration. These results show that TLR4 on both circulating leukocytes and intrinsic renal cells contributes to the inflammatory effects of antibody deposition within the glomerulus, which depends at least in part on the production of CXC chemokines by intrinsic renal cells.
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66
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Jones DL, Sacks SH, Wong W. Controlling the generation and function of human CD8+ memory T cells in vitro with immunosuppressants. Transplantation 2007; 82:1352-61. [PMID: 17130785 DOI: 10.1097/01.tp.0000241077.83511.be] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Memory T cells play a pivotal role in acute and chronic rejection of transplanted organs. Novel therapies such as alemtuzumab and the identification of heterologous memory have highlighted their importance following transplantation. Unlike naive T cells, the influence of immunosuppressive agents on the de novo generation of memory T cells and on the function of pre-existing memory T cells is poorly understood. METHOD CD8 effector memory T cells (Tem, CD45RA, CCR7) were generated by stimulating peripheral blood mononuclear cells for five days with anti-CD3 and anti-CD28 monoclonal antibodies, followed by nine days of rest. The influence of immunosuppression on this was assessed by flow cytometry. Tem that had been naturally formed in vivo were used to study the influence of the same agents on the function (intracellular interferon-gamma production) of Tem cells. RESULTS Whereas all the immunosuppressive agents tested inhibited the expansion of CD8 Tem population by influencing their proliferation and apoptosis, the calcineurin inhibitors were better at controlling their function. Furthermore, Tem generated despite the presence of tacrolimus were functional and did not exhibit drug resistance. CONCLUSIONS Immunosuppressive agents differ in their ability to control the generation and function of CD8 Tem; the calcineurin inhibitors being the most efficacious. This may be of importance when tailoring immunosuppressants for transplant recipients, particularly in those where there is pre-existing immunological memory or in those receiving T-cell depleting therapies, which skews the immune repertoire towards memory.
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67
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Anderson K, Li K, Peng Q, Villiers MB, Sacks SH, Zhou W. Production of C3 by DCs modulates their capacity for antigen uptake and processing. Mol Immunol 2007. [DOI: 10.1016/j.molimm.2006.07.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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68
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Farrar CA, Zhou W, Lin T, Sacks SH. Locally produced extravascular pool of complement is crucial in mediating post-ischemic acute renal failure. Mol Immunol 2007. [DOI: 10.1016/j.molimm.2006.07.053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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69
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Peng Q, Li K, Sacks SH, Zhou W. Alternative pathway mediated generation of C3a regulates the allostimulatory function of dendritic cells. Mol Immunol 2007. [DOI: 10.1016/j.molimm.2006.07.186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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70
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Lock HR, Sacks SH, Robson MG. Rapamycin at subimmunosuppressive levels inhibits mesangial cell proliferation and extracellular matrix production. Am J Physiol Renal Physiol 2007; 292:F76-81. [PMID: 16896187 DOI: 10.1152/ajprenal.00128.2006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In view of its proven antiproliferative effects, rapamycin offers potential in the treatment of mesangioproliferative disease. Previous data have shown an effect of rapamycin on mesangial cell proliferation at high doses and have not explored the mechanism of action. Therefore, we explored the effects and mechanism of action of low levels of rapamycin on mesangial cell proliferation. Primary cultures of mouse mesangial cells were grown in medium containing serum with differing concentrations of rapamycin. A rapamycin concentration of 0.1 ng/ml caused a decrease in cell number and DNA synthesis with no effect on apoptosis. Type IV collagen protein production was inhibited at 0.01 ng/ml rapamycin, although gene expression was unaffected. P70S6K phosphorylation was inhibited in parallel with the effects on cell number and DNA synthesis in a dose-dependent manner, but no effect was seen at 0.01 ng/ml rapamycin. These data show an effect on mesangial cell proliferation and p70S6 kinase phosphorylation of 0.1 ng/ml rapamycin and an effect on collagen IV production of 0.01 ng/ml rapamycin. We suggest that further in vivo studies should explore the potential for low-dose rapamycin in the treatment of mesangioproliferative glomerulonephritis.
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Li K, Peng Q, Lin T, Noble A, Sacks SH, Zhou W. The presentation of exogenous antigen is dependent on dendritic cell C3. Mol Immunol 2007. [DOI: 10.1016/j.molimm.2006.07.137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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72
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Farmer CKT, Hampson G, Abbs IC, Hilton RM, Koffman CG, Fogelman I, Sacks SH. Late low-dose steroid withdrawal in renal transplant recipients increases bone formation and bone mineral density. Am J Transplant 2006; 6:2929-36. [PMID: 17061994 DOI: 10.1111/j.1600-6143.2006.01557.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Corticosteroids have been the most widely used immunosuppressive agents since the first clinical transplantation in the 1950s. There are few studies of late steroid withdrawal in renal transplantation and none have prospectively assessed bone mineral density (BMD). The study aim was to assess the impact of corticosteroid withdrawal, in stable renal transplant recipients, on BMD and bone turnover. BMD, osteocalcin (OC) and cross-linked telopeptide of type I collagen (CTx) were measured in 92 patients randomized into a trial of steroid withdrawal. Patients with functioning renal transplants for more than 1 year with a serum creatinine below 200 micromol/L entered the trial. All patients were on triple immunosuppression (Cyclosporin microemulsion, Azathioprine and prednisolone), corticosteroids were withdrawn at 1 mg/month. BMD was measured twice annually with serum CTx and OC. One year following withdrawal of glucocorticoids there was no significant difference in creatinine. BMD increased in the withdrawal group (2.54% per year L1-L4, p < 0.01), there was a slight reduction in the control group. Mean OC increased from 5.3 to 12.2 ng/mL (p < 0.05) in the withdrawal group, but was unchanged in the controls. No change was seen in CTx. Corticosteroid withdrawal in renal transplant recipients results in an increase in BMD with a corresponding increase in serum OC.
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Chowdhury P, Sacks SH, Sheerin NS. Toll-like receptors TLR2 and TLR4 initiate the innate immune response of the renal tubular epithelium to bacterial products. Clin Exp Immunol 2006; 145:346-56. [PMID: 16879256 PMCID: PMC1809678 DOI: 10.1111/j.1365-2249.2006.03116.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Renal tubular epithelial cells (TECs) respond diffusely to local infection, with the release of multiple cytokines, chemokines and other factors that are thought to orchestrate the cellular constituents of the innate immune response. We have investigated whether the Toll-like receptors TLR4 and TLR2, which are present on tubular epithelium and potentially detect a range of bacterial components, co-ordinate this inflammatory response acting through nuclear factor-kappa B (NF-kappaB). Primary cultures of TECs were grown from C57BL/6, C3H/HeN, C3H/HeJ, TLR2 and TLR4 knock-out mice. Cell monolayers were stimulated with lipopolysaccharide (LPS) and synthetic TLR2 and 4 agonists. The innate immune response was quantified by measurement of the cytokines tumour necrosis factor (TNF)-alpha and KC (IL-8 homologue) in cell supernatants by enzyme-linked immunosorbent assay. Cultured TECs grown from healthy mice produced the cytokines TNF-alpha and KC in response to stimulation by LPS and synthetic TLR2 and TLR4 agonists. Cells lacking the respective TLRs had a reduced response to stimulation. The TLR2- and TLR4-mediated response to stimulation was dependent on NF-kappaB signalling, as shown by curcumin pretreatment of TECs. Finally, apical stimulation of these TLRs elicited basal surface secretion of TNF-alpha and KC (as well as the reverse), consistent with the biological response in vivo. Our data highlight the potential importance of TLR-dependent mechanisms co-ordinating the innate immune response to upper urinary tract infection.
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74
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Brown HJ, Lock HR, Sacks SH, Robson MG. TLR2 stimulation of intrinsic renal cells in the induction of immune-mediated glomerulonephritis. THE JOURNAL OF IMMUNOLOGY 2006; 177:1925-31. [PMID: 16849506 DOI: 10.4049/jimmunol.177.3.1925] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Infection may exacerbate organ-specific autoimmune disease such as glomerulonephritis. This may occur in the absence of a measurable effect on the adaptive immune response, and the mechanisms responsible are not fully understood. To investigate this, we have studied the effect of TLR2 ligation by the synthetic ligand Pam(3)CysSK(4) on the development of glomerulonephritis in mice. We demonstrated that glomerular inflammation induced by passive administration of nephrotoxic Ab does not occur in the absence of TLR2 stimulation, with a strong synergy when Ab deposition and TLR2 stimulation occur together. Parameters of glomerular inflammation were neutrophil influx, thrombosis, and albuminuria. To investigate the relative contribution of TLR2 on bone marrow-derived cells and intrinsic renal cells, we constructed bone marrow chimeras. Nephrotoxic Ab and TLR2 ligation caused a neutrophil influx in both types of chimera above [corrected] that seen in sham chimeras totally TLR2 deficient [corrected] Albuminuria was seen in both types of chimera above that seen in sham chimeras that were totally TLR2 deficient. This was greater in chimeras with TLR2 present on bone marrow-derived cells. To find a potential mechanism by which intrinsic renal cells may contribute toward disease exacerbation, mesangial cells were studied and shown to express TLR2 and MyD88. Wild-type but not TLR2-deficient mesangial cells produced CXC chemokines in response to stimulation with Pam(3)CysSK(4). These results demonstrate that TLR2 stimulation on both bone marrow-derived and resident tissue cells plays a role in amplifying the inflammatory effects of Ab deposition in the glomerulus.
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75
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Li K, Feito MJ, Sacks SH, Sheerin NS. CD46 (Membrane Cofactor Protein) Acts as a Human Epithelial Cell Receptor for Internalization of Opsonized UropathogenicEscherichia coli. THE JOURNAL OF IMMUNOLOGY 2006; 177:2543-51. [PMID: 16888016 DOI: 10.4049/jimmunol.177.4.2543] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Escherichia coli is a common urinary pathogen whose uptake into epithelial cells is mediated by attachment through type 1 fimbriae. In this study, we show by using using human urinary tract epithelial cells that maximal internalization of E. coli is achieved only when bacteria are opsonized with complement. The concentrations of complement proteins in the urine rise sufficiently during infection to allow bacterial opsonization. The complement regulatory protein, CD46 (membrane cofactor protein), acts in cohort with fimbrial adhesion to promote the uptake of pathogenic E. coli. This uptake is inhibited by RNA interference to lower the expression of CD46 and by soluble CD46 that will competitively inhibit opsonized bacteria binding to cell surface CD46. We propose that efficient internalization of uropathogenic E. coli by the human urinary tract depends on cooperation between fimbrial-mediated adhesion and C3 receptor (CD46)-ligand interaction. Complement receptor-ligand interaction could pose a new target for interrupting the cycle of reinfection due to intracellular bacteria.
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