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Wu T, Rayner CK, Jones KL, Horowitz M, Feinle-Bisset C, Standfield SD, Xie C, Deacon CF, Holst JJ, Wewer Albrechtsen NJ. Measurement of plasma glucagon in humans: A shift in the performance of a current commercially available radioimmunoassay kit. Diabetes Obes Metab 2022; 24:1182-1184. [PMID: 35188324 DOI: 10.1111/dom.14673] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 02/16/2022] [Accepted: 02/16/2022] [Indexed: 01/14/2023]
Affiliation(s)
- Tongzhi Wu
- Adelaide Medical School and Centre of Research Excellence (CRE) in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, South Australia, Australia
- Endocrine and Metabolic Unit, Royal Adelaide Hospital, Adelaide, South Australia, Australia
| | - Christopher K Rayner
- Adelaide Medical School and Centre of Research Excellence (CRE) in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, South Australia, Australia
- Department of Gastroenterology and Hepatology, Royal Adelaide Hospital, Adelaide, South Australia, Australia
| | - Karen L Jones
- Adelaide Medical School and Centre of Research Excellence (CRE) in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, South Australia, Australia
- Endocrine and Metabolic Unit, Royal Adelaide Hospital, Adelaide, South Australia, Australia
| | - Michael Horowitz
- Adelaide Medical School and Centre of Research Excellence (CRE) in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, South Australia, Australia
- Endocrine and Metabolic Unit, Royal Adelaide Hospital, Adelaide, South Australia, Australia
| | - Christine Feinle-Bisset
- Adelaide Medical School and Centre of Research Excellence (CRE) in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, South Australia, Australia
| | - Scott D Standfield
- Adelaide Medical School and Centre of Research Excellence (CRE) in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, South Australia, Australia
| | - Cong Xie
- Adelaide Medical School and Centre of Research Excellence (CRE) in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, South Australia, Australia
- Endocrine and Metabolic Unit, Royal Adelaide Hospital, Adelaide, South Australia, Australia
| | - Carolyn F Deacon
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jens J Holst
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Nicolai J Wewer Albrechtsen
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Foundation Centre for Protein Research, University of Copenhagen, Copenhagen, Denmark
- Department of Clinical Biochemistry, Diagnostic Center, Copenhagen University Hospital - Rigshospitalet, Copenhagen, Denmark
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Wu T, Bound MJ, Standfield SD, Bellon M, Young RL, Jones KL, Horowitz M, Rayner CK. Artificial sweeteners have no effect on gastric emptying, glucagon-like peptide-1, or glycemia after oral glucose in healthy humans. Diabetes Care 2013; 36:e202-3. [PMID: 24265374 PMCID: PMC3836145 DOI: 10.2337/dc13-0958] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Tongzhi Wu
- Corresponding author: Christopher K. Rayner,
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Wu T, Bound MJ, Zhao BR, Standfield SD, Bellon M, Jones KL, Horowitz M, Rayner CK. Effects of a D-xylose preload with or without sitagliptin on gastric emptying, glucagon-like peptide-1, and postprandial glycemia in type 2 diabetes. Diabetes Care 2013; 36:1913-8. [PMID: 23359361 PMCID: PMC3687261 DOI: 10.2337/dc12-2294] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
OBJECTIVE Macronutrient "preloads" can reduce postprandial glycemia by slowing gastric emptying and stimulating glucagon-like peptide-1 (GLP-1) secretion. An ideal preload would entail minimal additional energy intake and might be optimized by concurrent inhibition of dipeptidyl peptidase-4 (DPP-4). We evaluated the effects of a low-energy D-xylose preload, with or without sitagliptin, on gastric emptying, plasma intact GLP-1 concentrations, and postprandial glycemia in type 2 diabetes. RESEARCH DESIGN AND METHODS Twelve type 2 diabetic patients were studied on four occasions each. After 100 mg sitagliptin (S) or placebo (P) and an overnight fast, patients consumed a preload drink containing either 50 g D-xylose (X) or 80 mg sucralose (control [C]), followed after 40 min by a mashed potato meal labeled with (13)C-octanoate. Blood was sampled at intervals. Gastric emptying was determined. RESULTS Both peak blood glucose and the amplitude of glycemic excursion were lower after PX and SC than PC (P < 0.01 for each) and were lowest after SX (P < 0.05 for each), while overall blood glucose was lower after SX than PC (P < 0.05). The postprandial insulin-to-glucose ratio was attenuated (P < 0.05) and gastric emptying was slower (P < 0.01) after D-xylose, without any effect of sitagliptin. Plasma GLP-1 concentrations were higher after D-xylose than control only before the meal (P < 0.05) but were sustained postprandially when combined with sitagliptin (P < 0.05). CONCLUSIONS In type 2 diabetes, acute administration of a D-xylose preload reduces postprandial glycemia and enhances the effect of a DPP-4 inhibitor.
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Affiliation(s)
- Tongzhi Wu
- Discipline of Medicine, University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia
- Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
| | - Michelle J. Bound
- Discipline of Medicine, University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia
- Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
| | - Beiyi R. Zhao
- Discipline of Medicine, University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia
- Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
| | - Scott D. Standfield
- Discipline of Medicine, University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia
- Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
| | - Max Bellon
- Department of Nuclear Medicine, Royal Adelaide Hospital, Adelaide, Australia
| | - Karen L. Jones
- Discipline of Medicine, University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia
- Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
| | - Michael Horowitz
- Discipline of Medicine, University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia
- Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
| | - Christopher K. Rayner
- Discipline of Medicine, University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia
- Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
- Corresponding author: Chris K. Rayner,
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Wu T, Bound MJ, Standfield SD, Gedulin B, Jones KL, Horowitz M, Rayner CK. Effects of rectal administration of taurocholic acid on glucagon-like peptide-1 and peptide YY secretion in healthy humans. Diabetes Obes Metab 2013. [PMID: 23181598 DOI: 10.1111/dom.12043] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Glucagon-like peptide-1 (GLP-1) and peptide YY (PYY), secreted by enteroendocrine L-cells located most densely in the colon and rectum, are of fundamental importance in blood glucose and appetite regulation. In animal models, colonic administration of bile acids can stimulate GLP-1 and PYY by TGR5 receptor activation. We evaluated the effects of taurocholic acid (TCA), administered as an enema, on plasma GLP-1 and PYY, as well as gastrointestinal sensations in 10 healthy male subjects, and observed that rectal administration of TCA promptly stimulated secretion of both GLP-1 and PYY, and increased fullness, in a dose-dependent manner. These observations confirm that topical application of bile acids to the distal gut may have potential for the management of type 2 diabetes and obesity.
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Affiliation(s)
- T Wu
- Discipline of Medicine, University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia
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Wu T, Bound MJ, Standfield SD, Jones KL, Horowitz M, Rayner CK. Effects of taurocholic acid on glycemic, glucagon-like peptide-1, and insulin responses to small intestinal glucose infusion in healthy humans. J Clin Endocrinol Metab 2013; 98:E718-22. [PMID: 23418316 DOI: 10.1210/jc.2012-3961] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
CONTEXT In vitro and animal studies suggest that bile acids have the capacity to reduce blood glucose by stimulating glucagon-like peptide-1 (GLP-1) and, thereby, insulin. OBJECTIVE This study evaluated the effects of intrajejunal taurocholic acid (TCA) on blood glucose, GLP-1, and insulin responses to jejunal glucose infusion in healthy men. PARTICIPANTS AND DESIGN Ten healthy men were each studied on 2 days in a double-blind, randomized order. After the subjects fasted overnight, a jejunal catheter was positioned and a balloon inflated 30 cm beyond the pylorus with aspiration of endogenous bile. Two grams TCA in saline, or saline control, was infused beyond the balloon over 30 minutes, followed by 2 g TCA or control, together with 60 g glucose, over the next 120 minutes. Blood was sampled frequently for the measurements of blood glucose, total GLP-1, insulin, C-peptide, and glucagon. RESULTS Intrajejunal infusion of TCA alone (t = -30 to 0 minutes) had no effect on blood glucose, GLP-1, insulin, C-peptide, or glucagon concentrations. During intrajejunal glucose infusion (t = 0 to 120 minutes), blood glucose concentrations were lower (P < .001), and plasma GLP-1 (P < .001) and the C-peptide/glucose ratio (P = .008) were both greater, whereas plasma insulin, C-peptide, and glucagon levels were not significantly different after TCA than after control. CONCLUSIONS In healthy humans, small intestinal infusion of TCA potently reduces the glycemic response to small intestinal glucose, associated with an increase in GLP-1 and C-peptide/glucose ratio. These observations indicate the potential for bile acid-based therapy in type 2 diabetes.
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Affiliation(s)
- Tongzhi Wu
- Discipline of Medicine, Royal Adelaide Hospital, North Terrace, Adelaide, South Australia 5000, Australia
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Abstract
BACKGROUND/AIMS Constitutive expression of Fas ligand (CD95L) protects the eye against cell mediated immune responses by inducing apoptosis in infiltrating Fas bearing T cells. This study was designed to examine Fas ligand expression on acutely rejecting rat corneal grafts and to investigate the kinetics of induction of apoptosis in infiltrating leucocytes. METHODS Orthotopic penetrating corneal transplantation was performed between genetically disparate inbred rats. Fas ligand expression and the phenotype of infiltrating leucocytes were examined by immunohistochemistry. Apoptotic nuclei were visualised in sections of normal rat cornea, rejecting allografts, and time matched isografts by terminal deoxynucleotidyl transferase mediated dUTP biotin nick end labelling (TUNEL) and quantified by video image analysis. Staining with Hoechst dye 33258 was used to confirm the presence of apoptotic nuclei. RESULTS Fas ligand was expressed on corneal endothelial and epithelial cells during acute corneal graft rejection. At all time points examined, including as early as the fifth postoperative day, the cells infiltrating both corneal isografts and allografts were TUNEL positive. By the 15th postoperative day, over 90% of all nuclei, many of which were T cells, were apoptotic. CONCLUSION Expression of Fas ligand is not downregulated on the cornea during allograft rejection and infiltrating leucocytes in both isografts and allografts die rapidly in situ. Despite the death of the cells believed to be responsible for rejection, isografts survive indefinitely whereas allografts are irreparably damaged.
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Affiliation(s)
- K A Williams
- Department of Ophthalmology, Flinders Medical Centre, Bedford Park, SA 5042, Australia.
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Williams KA, Brereton HM, Farrall A, Standfield SD, Taylor SD, Kirk LA, Coster DJ. Topically applied antibody fragments penetrate into the back of the rabbit eye. Eye (Lond) 2004; 19:910-3. [PMID: 15359243 DOI: 10.1038/sj.eye.6701669] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
AIMS Antibody fragments have been shown to penetrate into the anterior chamber when applied to the cornea. The aim of this study was to investigate whether such fragments could penetrate into the vitreous cavity after topical administration to the ocular surface of rabbits. METHODS An engineered single-chain variable-domain antibody fragment with specificity for an irrelevant rat determinant was applied as a 50 microl eye drop to the eyes of live rabbits at 20-min intervals over 12 h. Eye drops contained 0.8-1.1 mg/ml protein in a buffered salt solution supplemented with penetration and viscosity enhancers. Samples were collected by paracentesis from the vitreous cavity immediately postmortem. Antibody fragments in these samples were quantified by measuring the binding activity to specific antigen, using flow cytometry. RESULTS Topically applied antibody fragments were detectable in the vitreous of rabbit eyes after 4-12 h but had cleared at 12 h following the final eye drop. Concentrations of the antibody fragment in the vitreous samples were estimated to be 50-150 ng/ml at 12 h. Penetration of the parental whole antibody into the vitreous was not observed. CONCLUSION Antibody fragments penetrate into the vitreous chamber of the rabbit eye after topical administration to the ocular surface. Such fragments may have therapeutic potential for diseases affecting the posterior segment.
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Affiliation(s)
- K A Williams
- Department of Ophthalmology, Flinders University of South Australia, Adelaide, Australia.
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Thiel MA, Coster DJ, Standfield SD, Brereton HM, Mavrangelos C, Zola H, Taylor S, Yusim A, Williams KA. Penetration of engineered antibody fragments into the eye. Clin Exp Immunol 2002; 128:67-74. [PMID: 11982592 PMCID: PMC1906367 DOI: 10.1046/j.1365-2249.2002.01808.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Antibodies are powerful immunotherapeutic agents but their use for treating ocular disorders is limited by their poor penetration into the eye. We hypothesized that antibody fragments of relatively small size might penetrate the cornea more readily. Monovalent single chain variable region (scFv) antibody fragments and divalent miniantibodies were engineered from existing monoclonal antibodies, expressed in a bacterial expression system, and purified by metal ion affinity chromatography. Corneoscleral preparations from normal pig and cat eyes were mounted in a corneal perfusion chamber. Intact antibodies and antibody fragments were applied topically to the anterior corneal surface over 12-h periods, and samples were collected from the artificial anterior chamber. Similar experiments were performed with whole enucleated pig and human eyes. Penetration of antibodies and fragments was quantified by high-sensitivity flow cytometry on appropriate target cells. Both monovalent scFv and divalent miniantibody fragments (but not whole immunoglobulin molecules) passed through de-epithelialized and intact corneas after topical administration, and could be detected by antigen binding. Addition of 0.5% sodium caprate facilitated penetration through intact corneas. Topically-applied scFv was found to penetrate into the anterior chamber fluid of rabbit eyes in vivo. The engineered fragments were stable and resistant to ocular proteases. Monovalent and divalent antibody constructs of molecular weight 28 kD and 67 kD, respectively, can penetrate through intact corneas into the anterior chamber, with retention of appropriate antigen-binding activity. Such constructs may form novel therapeutic agents for topical ophthalmic use.
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Affiliation(s)
- M A Thiel
- Department of Ophthalmology, Flinders University of South Australia, Adelaide, Australia
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Smith JR, Hart PH, Standfield SD, Coster DJ, Wing SJ, Williams KA. Apoptosis is a prominent feature of acute anterior uveitis in the Fischer 344 rat. Br J Ophthalmol 2000; 84:205-11. [PMID: 10655199 PMCID: PMC1723389 DOI: 10.1136/bjo.84.2.205] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AIMS To examine the hypothesis that apoptosis of infiltrating cells contributes to spontaneous resolution of uveitis in clinically relevant rodent models. METHODS Experimental melanin induced uveitis (EMIU) was induced in Fischer 344 rats by immunisation with 250 microg bovine ocular melanin. Endotoxin induced uveitis (EIU) was induced by injection of 200 microg Escherichia coli lipopolysaccharide. Formalin fixed, paraffin embedded ocular cross sections were stained by terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate biotin nick end labelling (TUNEL) to identify apoptotic cells. Indirect immunoperoxidase staining of paraformaldehyde lysine periodate fixed tissue cross sections was used to demonstrate expression of inducible nitric oxide synthase (iNOS). RESULTS TUNEL positive mononuclear cells were observed in the anterior uvea during both EMIU and EIU at all selected time points. However, whereas the majority of mononuclear cells appeared apoptotic from the outset of disease, neutrophils were notably TUNEL negative at all time points examined. Many infiltrating neutrophils expressed iNOS. CONCLUSION Apoptosis occurs early in the course of rat EMIU and EIU, and may contribute to resolution of these diseases. In general, infiltrating mononuclear cells die rapidly, while neutrophils survive, producing inducible nitric oxide synthase which may contribute to disease pathogenesis.
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Affiliation(s)
- J R Smith
- Department of Ophthalmology, Flinders University of South Australia, Adelaide, Australia
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Williams KA, Standfield SD, Mills RA, Takano T, Larkin DF, Krishnan R, Russ GR, Coster DJ. A new model of orthotopic penetrating corneal transplantation in the sheep: graft survival, phenotypes of graft-infiltrating cells and local cytokine production. Aust N Z J Ophthalmol 1999; 27:127-35. [PMID: 10379711 DOI: 10.1046/j.1440-1606.1999.00171.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Orthotopic penetrating keratoplasty in the sheep was developed as an outbred preclinical model to allow correlation of the cellular infiltrate during graft rejection with local production of cytokine mRNA. METHODS Penetrating corneal autografts and allografts were performed in Merino sheep. Graft outcome was followed at the slit-lamp. Corneal infiltrates were examined by immunoperoxidase staining on postmortem specimens. Cytokine mRNA was detected by polymerase chain reaction. RESULTS Corneal autografts survived indefinitely. Allografts became vascularized and underwent rejection at a median of 20 days postgraft. Both endothelial and epithelial rejection lines were observed. Immunohistochemical staining of rejecting grafts showed up-regulation of major histocompatibility complex class I molecules on corneal graft epithelium, damaged or absent graft endothelium and a marked, predominantly mononuclear cell infiltrate. CD4-positive T cells were observed in the graft within 2 days of the onset of rejection, followed several days later by CD8-positive T cells. Messenger RNA transcripts for interleukin (IL)-2, tumour necrosis factor (TNF)-alpha and IL-10 (but not for interferon (IFN)-gamma or IL-4) were found in autografted corneas. Proportionately, more allografts than autografts contained transcripts for IL-2 and TNF-alpha, and IFN-gamma was detected in three of four allografts. CONCLUSIONS Corneal graft rejection in the sheep is macroscopically and histologically similar to human corneal graft rejection. Allografts become infiltrated by both CD4- and CD8-positive T cells and local production of pro-inflammatory cytokines occurs during graft rejection.
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Affiliation(s)
- K A Williams
- Flinders University of South Australia, Adelaide, Australia.
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Smith JR, Hart PH, Parish CR, Standfield SD, Coster DJ, Williams KA. Experimental melanin-induced uveitis in the Fischer 344 rat is inhibited by anti-CD4 monoclonal antibody, but not by mannose-6-phosphate. Clin Exp Immunol 1999; 115:64-71. [PMID: 9933421 PMCID: PMC1905186 DOI: 10.1046/j.1365-2249.1999.00765.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Experimental melanin-induced uveitis (EMIU) is a rodent model of acute anterior uveitis which was described in 1993. We investigated strain susceptibility, and age and gender characteristics of the model, undertook histological and immunohistochemical studies to investigate underlying cellular mechanisms, and examined several treatment options. Rats were immunized with bovine ocular melanin (250 microg), and disease was followed by slit lamp examination. Lewis, Fischer 344 and Porton rats were found to be susceptible to EMIU, whereas Wistar-Furth, DA, and Hooded Wistar strains were resistant. EMIU was neither age- nor gender-dependent. In Fischer 344 rats, EMIU was characterized clinically by florid anterior segment inflammation. Histopathological findings included infiltration of ciliary body and iris with mononuclear cells and neutrophils. Both CD4+ and CD8+ T lymphocytes were prominent. Rats were then treated with intraperitoneal injections of anti-CD4, anti-CD8 or irrelevant isotype-matched MoAb on days -3, 0, 3, 6 and 9 with respect to melanin immunization. Incidence of uveitis was significantly reduced in rats treated with a non-depleting cocktail of anti-CD4 MoAbs (P = 0.007), whereas a depleting anti-CD8 antibody had no effect on the disease. Mannose-6-phosphate inhibits lymphocyte migration in some models of T cell-mediated inflammation. This simple sugar was administered to additional rats via intraperitoneal osmotic pumps for 14 days following disease induction, but did not influence the uveitis. We conclude that EMIU is controlled by CD4+ T cells, and disease may be abrogated by treatment with anti-CD4 MoAbs.
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Affiliation(s)
- J R Smith
- Department of Ophthalmology, Flinders University of South Australia, Adelaide, Australia
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Abstract
Orthotopic penetrating guinea pig to rat and chicken to rat corneal xenografts were performed to examine the nature of the host response. Guinea pig to rat xenografts failed at a median of day 3 after surgery. A similar but slightly accelerated pattern of failure was seen in guinea pig xenografts performed in prevascularized recipient rat corneas. Chicken to rat xenografts failed at a median of day 2 after grafting. Rat corneal isograft controls survived indefinitely. Corneal endothelial cells were visible by silver staining on the xenografts immediately after operation, which indicates that failure was not due to loss of these cells during surgery. Histopathology and immunoperoxidase staining indicated that xenograft failure in euthymic recipients was characterized by early corneal epithelial and endothelial cell damage, granulocytic infiltration, and hemorrhage from recipient corneal and iris capillaries, followed at 7-14 days by infiltration with T cells, macrophages, and eosinophils. An accelerated pattern of graft failure was also observed in guinea pig grafts into homozygous nude rat recipients, which suggests that preformed anti-donor antibody and complement were responsible for some of the early graft damage. Flow cytometry demonstrated the presence of pre-existing natural antibodies to guinea pig and chicken lymphocytes and erythrocytes, as expected from other studies. Immunohistochemistry showed the presence of rat IgG2a, IgG1, and IgM, but not IgD deposited on grafts in immunocompetent recipients on the first postoperative day. We conclude that orthotopic corneal xenografts undergo substantial accelerated damage mediated by pre-existing antibody, followed at 7-14 days by a cell-mediated response that causes further destruction.
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Affiliation(s)
- D F Larkin
- Department of Ophthalmology, Flinders University of South Australia
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Williams KA, Standfield SD, Wing SJ, Barras CW, Mills RA, Comacchio RM, Coster DJ. Patterns of corneal graft rejection in the rabbit and reversal of rejection with monoclonal antibodies. Transplantation 1992; 54:38-43. [PMID: 1631942 DOI: 10.1097/00007890-199207000-00006] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The purpose of this study was to determine whether the local administration of monoclonal antibodies could reverse rabbit corneal graft rejection. To provide a rational basis for the choice of monoclonal antibodies as potential immunosuppressive agents, the phenotypes of cells infiltrating rejecting rabbit corneal allografts were examined by immunohistochemistry. About half the leukocytes accumulating in these grafts bore an immunodominant T cell marker, over two-thirds carried MHC class II antigens, and about one-fifth carried myeloid cell markers. A kinetic study of the cell population appearing in rabbit aqueous during corneal graft rejection was performed by examination of repetitive anterior chamber taps taken over a ten-day period; again, the major components were T cells, MHC class II antigen-positive cells and myeloid cells. Monoclonal antibodies L11/135 (directed against a peripheral T cell determinant), 2C4 (directed against a monomorphic MHC class II antigen), and LION 2 (directed against a myeloid antigen) were chosen for intracameral injection into rabbits with rejecting corneal grafts. Each animal received a total of 50-100 micrograms of antibody in two injections at 3-4-day intervals. L11/135 and LION 2 reversed rejection in 5/9 and 8/12 animals, respectively, in the absence of any other immunosuppression; 2C4 was without effect. We suggest that monoclonal antibody therapy in corneal transplantation deserves further attention.
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Affiliation(s)
- K A Williams
- Department of Ophthalmology, Flinders University of South Australia, Adelaide
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