Anti-CD20 antibody suppresses anti-HLA antibody formation in a HLA-A2 transgenic mouse model of sensitization

BACKGROUND: B cell depletion by anti-CD20 antibody is used in desensitization protocols and for treatment of antibody-mediated rejection (AMR). However, little is known about the efficacy and the mechanism(s) of action. METHODS: A mouse model of HLA sensitization was used to study the effectiveness of anti-CD20 treatment on B cell depletion and anti-HLA antibody suppression. RESULTS: Immunization of C57BL/6 mice with skin grafts from a transgenic C57BL.Tg/HLA-A2.1 mouse resulted in robust production of anti-HLA IgM and IgG antibodies, and accelerated rejection of a secondary skin allograft (within 3 days) featured by intragraft IgG and C4d deposition. Both IgM and IgG alloantibodies are specific to HLA-A2 as well as to a panel of class I HLA, including A1, A3, A25, A26, A29, and A30. These alloantibodies were complement-dependently cytotoxic (CDC) against HLA-A2 expressing target cells. Administration of 2 doses of a mouse-anti-mouse CD20 monoclonal antibody significantly reduced the levels of anti-HLA IgG2a antibodies, suppressed serum CDC, and prolonged survival of the secondary skin allografts. Suppression of anti-HLA IgG antibodies was associated with significant depletion of B220(+)/CD5(-) B cells from the blood, the spleen and the bone marrow of the treated animals. CONCLUSION: Anti-CD20 treatment effectively depletes B220(+)/CD5(-) B cells, resulting in potent suppression of anti-HLA IgG and prolongation of skin graft survival. The data are in support for the use of anti-CD20 antibodies in highly-HLA sensitized patients undergoing desensitization and for the treatment of AMR.     

Cellular cardiomyoplasty in a transgenic mouse model

BACKGROUND: Recent progress in the cardiotypic differentiation of embryonic and somatic stem cells opens novel prospects for the treatment of cardiovascular disorders. The aim of the present study was to develop a novel surgical approach that allows standardized cellular cardiomyoplasty in mouse with low-perioperative mortality. METHODS: Reproducible transmural lesions were generated by cryoinjury followed by intramural injection of embryonic cardiomyocytes using a newly designed holding device and vital dye staining. This approach was validated with a transgenic mouse model, in which the live reporter gene-enhanced green fluorescent protein (EGFP) is under control of a cardiac-specific promoter. RESULTS: The perioperative mortality was 10%. The engrafted EGFP-positive cardiomyocytes could be identified in a high percentage (72.2%, n=36) of operated animals. CONCLUSIONS: This novel approach enables reliable cellular replacement therapy in mouse and greatly facilitates the analysis of its molecular, cellular, and functional efficacy.     

Ibrutinib suppresses alloantibody responses in a mouse model of allosensitization

BackgroundIbrutinib is a Bruton's tyrosine Kinase (BTK) antagonist that inhibits B cell receptor (BCR) signaling. Complete BTK deficiency is associated with absence of B-cells. Ibrutinb is currently approved by FDA for treatment of B-cell malignancies, including Waldenström macroglobulinaemia. We recently carried out studies to determine if ibrutinib could modify alloantibody responses.Materials and methodsA mouse model of allogenic sensitization using a C57BL/6 mouse as the recipient of a skin allograft from an HLA-A2 transgenic mouse was utilized to examine the effects of ibrutinib on alloantibody responses and B cell effector functions. Donor-specific antibody (DSA) levels were measured in a flow-cytometric antibody binding assay. Splenic T and B cell subsets and plasma cells were analyzed in flow cytometry.ResultsControl mice developed peak levels of DSA IgM at day 14 PTx while the ibrutinib treated mice had significantly lower levels of DSA IgM (p = 0.0047). Control mice developed HLA.A2-specific IgG antibodies at day 14 (230 ± 60 MFI) and reached peak levels at day 21 (426 ± 61 MFI). In contrast, mice in the treatment group had low levels of HLA.A2-specific IgG at day 14 (109 ± 59 MFI, p = 0.004) and day 21 (241 ± 86 MFI, p = 0.003). FACS analysis found a reduction of B220⁺ or CD19⁺ B cell population (p < 0.05). In addition, ibrutinib attenuated recall DSA IgG responses to re-sensitization (p < 0.05) and reduced CD38⁺ CD138⁺ plasma cells (p < 0.05) in the spleens.ConclusionsIbrutinib is effective in suppressing alloantibody responses through blocking BTK-mediated BCR signaling, leading to reduction of B cells and short-lived plasma cells in the spleens. Use of ibrutinib may provide benefits to HLA-sensitized transplant patients for alloantibody suppression.     

Anti-CD2 monoclonal antibody and tacrolimus in adult liver transplantation

BACKGROUND: Blockade of costimulation and adhesion signaling is an attractive approach to interfere with graft rejection METHODS: Between January 1997 and May 1999, forty adults having benign liver diseases were included in a prospective, randomized study comparing tacrolimus plus low-dose short-term steroids without (n=20, TAC group) or with a 10-day course of antihuman CD2 monoclonal antibody (n=20, BTI group). RESULTS: At day 7, histological rejection expressed by mean Banff scores (2.3+/-1.6 vs. 5.4+/-1.6 in the TAC group; P<0.0001) and incidence of moderate to severe rejection (score>or=6) (0 vs. 10 [50%] in the TAC group; P<0.001) were significantly lower in the BTI group. Rejection was treated in 10% (two patients) of BTI patients during the first 3 months and in 15% during the whole follow-up and in 25% (five patients) of TAC patients (P=NS). None of the BTI-patients presented with an adverse event. Three-month, 1-year, and 5-year actual patient survival rates were 100%, 95%, and 95% in the BTI group and 100%, 100%, and 85% in the TAC group. Graft survival rates were 100%, 90%, and 90% in the BTI group and 95%, 95%, and 80% in the TAC group (P=NS). The mAb had no negative impact on infectious or tumor events. CONCLUSIONS: Antihuman CD2 monoclonal antibody is a safe immunosuppressive drug which has a favorable impact on early immunological follow-up of liver transplanted patients. The antibody had no impact on late patient and graft survival.     

Anti-CD20 monoclonal antibody treatment of Epstein-Barr virus-induced intrahepatic lymphoproliferative disorder following liver transplantation

Epstein-Barr virus (EBV)-associated post-transplant lymphoproliferative disorders (PTLDs) are a common cause of death in transplant patients. Their incidence following liver transplantation is reported to be between 0.5% and 4%. Despite various therapeutic approaches, there is still no consensus on a treatment strategy. The treatment of transplant recipients with monoclonal antibodies directed against B-cell antigens is a new, therapeutic approach with which, however, little clinical experience has so far been gained. Two patients developed intrahepatic PTLD 7 and 15 months, respectively, after transplantation. In one case, this was diagnosed as polymorphic PTLD, in the other as monomorphic, monoclonal PTLD. After having their immunosuppression terminated, 4 weeks after establishment of the diagnosis, both patients were treated with anti-CD20 antibodies (rituximab) at a dose of 375 mg/m(2) on days 1, 8, 15 and 22. Treatment with rituximab was tolerated well by both patients. One of the patients in whom cholestasis parameters remained high underwent re-transplantation. In one of the cases, the histological work-up confirmed necrosis of 90% of the tumour cells, and complete remission in the other. Both patients died of secondary complications 10 weeks and 10 months, respectively, after the diagnosis of PTLD. We can conclude that treatment of PTLD with Rituximab led to remission in both of our patients. Nevertheless, progression of cholestasis persisted, and both patients ultimately died of complications unrelated to PTLD.     

Pathobiology of autochthonous prostate cancer in a pre-clinical transgenic mouse model

BACKGROUND: Animal models that closely mimic clinical disease can be exploited to hasten the pace of translational research. To this end, we have defined windows of opportunity in the transgenic adenocarcinoma of the mouse prostate (TRAMP) model of prostate cancer as a paradigm for designing pre-clinical trials. METHODS: The incidence of cancer, metastasis, and distribution of pathology were examined as a function of time in TRAMP mice. The expression of various markers of differentiation were characterized. RESULTS: The TRAMP model develops progressive, multifocal, and heterogeneous disease. Each lobe of the prostate progressed at a different rate. Cytokeratin 8, E-cadherin, and androgen receptor (AR) were expressed during cancer progression but levels were reduced or absent in late stage disease. A distinct epithelial to neuroendocrine (ENT) shift was observed to be a stochastic event related to prostate cancer progression in TRAMP. CONCLUSIONS: This study will serve as the basis for the rational design of pre-clinical studies with genetically engineered mouse models.     

Anti-CD20 monoclonal antibody therapy in Epstein-Barr Virus-associated B cell lymphoma following lung transplantation.

Post-transplant lymphoproliferative disease is a complication of bone marrow and solid organ transplantation, mostly associated with Epstein-Barr virus infection and chronic immunosuppression. Even if spontaneous resolution after cessation of immunosuppressive therapy can be observed, the prognosis of this disorder is usually poor with a low response to specific treatment. We describe a case of B-cell lymphoma of the nasopharynx occurring 6 months after double-lung transplantation. In spite of its monoclonal nature, anti-CD 20 monoclonal antibody given in the presence of reduced immunosuppression resulted in a complete response. The patient also received "consolidation" radiation therapy to prevent the recurrence. The treatment was well tolerated with minimal side effects. The patient was asymptomatic and had a well functioning graft more than 1 year after therapy.     

CMTM2改善环磷酰胺致转基因小鼠模型生殖毒性作用并影响StAR蛋白的表达

目的:探讨在转基因小鼠模型中CMTM2能否改善环磷酰胺(CP)引起的生殖毒性作用以及其对固醇合成快速调节蛋白(StAR)表达的影响。方法:随机选取CMTM2转基因小鼠20只分成2组:CMTM2+CP[CMTM2转基因小鼠腹腔内连续7 d注射50 mg/(kg.d)CP]组和CMTM2+NS(CMTM2转基因小鼠腹腔内连续7 d注射等量生理盐水)组,另取同源野生型C57BL/6J小鼠20只分成2组:WT+CP[野生型C57BL/6J小鼠腹腔内连续7 d注射50 mg/(kg.d)CP]组和WT+NS(野生型C57BL/6J小鼠腹腔内连续7 d注射等量生理盐水)组。30 d后各组小鼠处死取相应标本,放免法检测血清睾酮水平,分析各组小鼠精子浓度、精子活动率差异,Western印迹检测睾丸StAR蛋白表达。结果:对比CMTM2+NS组,CP能够降低CMTM2+CP组小鼠的血清睾酮含量[(42.98±3.25)nmol/L vs(46.74±3.38)nmol/L]、精子浓度[(16.89±1.17)×106/ml vs(24.68±0.95)×106/ml]以及精子活动率[(72.75±1.25)%vs(85.14±1.12)%](P<0.05),表现出明显的生殖毒性;对比WT+CP组,CMTM2+CP组小鼠血清睾酮[(42.98±3.25)nmol/L vs(37.97±4.17)nmol/L]、精子浓度[(16.89±1.17)×106/ml vs(12.75±1.02)×106/ml]以及精子活动率[(72.75±1.25)%vs(50.52±1.37)%]下降程度均明显减弱(P<0.05),而CMTM2+CP组的StAR蛋白表达水平则较高(1.16±0.07 vs 0.69±0.08,P<0.05)。结论:CMTM2可能通过调节StAR蛋白表达对抗CP引起的生殖毒性,从而在生殖系统中发挥一定的保护作用。     

Anti-CD20 monoclonal antibody (rituximab) therapy for acute cardiac humoral rejection: a case report

Humoral or antibody-mediated rejection in cardiac transplant recipients is mediated by donor-specific cytotoxic antibodies and is histologically defined by linear deposits of immunoglobulin and complement in the myocardial capillaries. Antibody-mediated rejection often is accompanied by hemodynamic compromise and is associated with reduced long-term graft survival. Standard immunosuppression, designed to target T cell immune function, is largely ineffective against this B cell-driven process. Current treatment options for humoral rejection are limited by a lack of specific anti-B cell therapies. We present the case of a 50-year-old woman with hemodynamically significant humoral rejection resistant to steroids, cyclophos-phamide, and plasmapheresis who responded to the addition of anti-CD20 monoclonal antibody therapy (rituximab). One year posttransplant, the patient is rejection-free, with normal left ventricular systolic function and coronary arteries.     

Increased dietary fat promotes islet amyloid formation and beta-cell secretory dysfunction in a transgenic mouse model of islet amyloid

Transgenic mice expressing the amyloidogenic human islet amyloid polypeptide (hIAPP) in their islet beta-cells are a model of islet amyloid formation as it occurs in type 2 diabetes. Our hIAPP transgenic mice developed islet amyloid when fed a breeder chow but not regular chow. Because the breeder chow contained increased amounts of fat, we hypothesized that increased dietary fat enhances islet amyloid formation. To test this hypothesis, we fed male hIAPP transgenic and nontransgenic control mice diets containing 15% (low fat), 30% (medium fat), or 45% (high fat) of calories derived from fat for 12 months, and we measured islet amyloid, islet endocrine cell composition, and beta-cell function. Increased dietary fat in hIAPP transgenic mice was associated with a dose-dependent increase in both the prevalence (percentage of islets containing amyloid deposits; 34 +/- 8, 45 +/- 8, and 58 +/- 10%, P < 0.05) and severity (percentage of islet area occupied by amyloid; 0.8 +/- 0.5, 1.0 +/- 0.5, and 4.6 +/- 2.5%, P = 0.05) of islet amyloid. In addition, in these hIAPP transgenic mice, there was a dose-dependent decrease in the proportion of islet area comprising beta-cells, with no significant change in islet size. In contrast, nontransgenic mice adapted to diet-induced obesity by increasing their islet size more than twofold. Increased dietary fat was associated with impaired insulin secretion in hIAPP transgenic (P = 0.05) but not nontransgenic mice. In summary, dietary fat enhances both the prevalence and severity of islet amyloid and leads to beta-cell loss and impaired insulin secretion. Because both morphologic and functional defects are present in hIAPP transgenic mice, this would suggest that the effect of dietary fat to enhance islet amyloid formation might play a role in the pathogenesis of the islet lesion of type 2 diabetes in humans.     

Y-position collagen II mutation disrupts cartilage formation and skeletal development in a transgenic mouse model of spondyloepiphyseal dysplasia.

Mice were generated by pronuclear injection of a type II collagen transgene harboring an Arg789Cys (R789C) mutation that has been found in patients with spondyloepiphyseal dysplasia (SED). Expression was directed to cartilage by the murine Col2a1 promoter to examine the consequences of mutations involving the Y-position of the collagen helix Gly-X-Y triplet on skeletogenesis. The transgenic mice had very short limbs, short trunk, short snout, and cleft palate; they died at birth. Their growth plates were disorganized and collagen fibrils were sparse in cartilage matrix. When the transgene was expressed in RCS cells, there was no evidence that R789C-bearing collagen chains were incorporated into stable collagen molecules. Molecular modeling of the mutation raised the possibility that it destabilizes the collagen triple helix. Together our results suggest that Y-position mutations, such as R789C, can act in a dominant negative manner to destabilize collagen molecules during assembly, reducing their availability to form fibrils, the deficiency of which profoundly disturbs the template functions of cartilage during skeletogenesis.     

HLA-A2 reactive antibodies in a patient who types as HLA-A2: The importance of high resolution typing and epitope-based antibody analysis

This report describes a case of a highly sensitized patient who had serum antibodies reacting with HLA-A2 but whose phenotype included HLA-A2. The determination of HLA mismatch acceptability at the antigen level was problematic, but high-resolution HLA typing information and epitope-based antibody specificity analysis based on the nonself-self paradigm of HLA epitope immunogenicity have provided a solution. This case supports the concept that HLA typing at the allele level offers a better approach to identifying suitable donors for sensitized patients.     

致敏受者移植肾存活率和抗HLA抗体的临床观察

目的观察致敏受者与非致敏受者移植肾存活率的差别,以及移植肾功能与抗HLA抗体变化的关系。方法纳入中山大学附属第一医院器官移植中心2000年4月至2008年12月间行肾移植后资料完整受者1309例。根据受者术前ELISA检测群体反应性抗体（PRA）的结果将受者分为50%≤PRA≤100%组（n=35）、10%≤PRA〈50%组（n=47）和PRA〈10%组（n=1227）。所有供受者采用PCR序列特异性引物进行HLA分型。运用标准HLA配型和氨基酸残基配型。采用Kaplan-Meier法对3组受者术后存活率进行组间生存分析。分析肾移植后抗HLA抗体的变化及其与移植肾功能和HLA错配的关系。结果随着随访时间增加,3组移植肾累积存活率均有下降。在术后3年内3组移植肾存活率差异较小（P〉0.05）,3年后3组移植肾存活率差异有统计学意义（P〈0.05）。10%≤PRA≤100%受者移植肾累积存活率显著低于PRA〈10%受者（P〈0.05）,50%≤PRA≤100%受者移植肾累积存活率也显著低于10%≤PRA〈50%受者（P〈0.05）。12例移植肾失功的受者中7例（58.3%）出现抗体增强,62例移植肾功能正常的受者中仅8例（12.9%）出现抗体增强,两者差异有统计学意义（P〈0.05）。出现新生抗体的受者抗体谱中,大多数包含有针对错配抗原的抗HLA抗体。结论无论是供者特异性还是非供者特异性抗体,抗HLA抗体的存在及其效价都会影响移植肾的存活。术后抗HLA抗体的变化与移植肾功能有关。     

Hepatocyte growth factor suppresses interstitial fibrosis in a mouse model of obstructive nephropathy

BACKGROUND: As tubulointerstitial fibrosis (TIF) reflects the prognosis of patients with various chronic renal diseases, the pathogenesis of TIF has to be clarified. Transforming growth factor-beta (TGF-beta) is a key mediator for renal fibrosis. We reported that hepatocyte growth factor (HGF) prevents renal fibrosis in nephrotic mice. However, the function of HGF in chronic renal failure, except for nephrotic syndrome, remains to be determined. METHODS: Using mice subjected to unilateral ureter-ligated obstruction (UUO), we investigated the roles of HGF in TIF, as induced by obstructive nephropathy. Pathophysiological changes in the kidney after UUO treatment were analyzed focusing on expressions of renal HGF and TGF-beta, TIF, tubular proliferation, and apoptosis. Neutralizing antibody against rodent HGF, or recombinant human HGF (rhHGF), was administrated to the UUO mice, and pathophysiological changes after neutralization or supplements of HGF were analyzed. RESULTS: In this UUO model, TIF with tubular apoptosis became evident, and it was accompanied by a decrease in renal HGF expression and an increase in renal TGF-beta expression. Neutralization of endogenous HGF accelerated the progression of TIF, accompanied by increases in TGF-beta expression and tubular apoptosis as well as by decreases in tubular proliferation. In contrast, rhHGF attenuated TIF progression, and there were decreases in TGF-beta expression and tubular apoptosis, and an increase in tubular proliferation. CONCLUSIONS: Endogenous as well as exogenous HGF attenuated the progression of the fibrosis caused by obstructive nephropathy in these mice. Thus, local reduction in HGF levels may account for TIF in chronic renal diseases.     

ARG098, a novel anti-human Fas antibody,suppresses synovial hyperplasia and prevents cartilage destruction in a severe combined immunodeficient-HuRAg mouse model

Background  

The anti-human Fas/APO-1/CD95 (Fas) mouse/human chimeric monoclonal IgM antibody ARG098 (ARG098) targets the human Fas molecule. The cytotoxic effects of ARG098 on cells isolated from RA patients, on normal cells in vitro, and on RA synovial tissue and cartilage in vivo using implanted rheumatoid tissues in an SCID mouse model (SCID-HuRAg) were investigated to examine the potential of ARG098 as a therapy for RA.     

Phloridzin improves hyperglycemia but not hepatic insulin resistance in a transgenic mouse model of type 2 diabetes

The chronic hyperglycemia that occurs in type 2 diabetes may cause deterioration of beta-cell function and insulin resistance in peripheral tissues. Mice that express a dominant-negative IGF-1 receptor, specifically in skeletal muscle (MKR mice), exhibit severe insulin resistance, hyperinsulinemia, dyslipidemia, and hyper-glycemia. To determine the role of hyperglycemia in the worsening of the diabetes state in these animals, MKR mice were treated with phloridzin (PHZ), which inhibits intestinal glucose uptake and renal glucose reabsorption. Blood glucose levels were decreased and urine glucose levels were increased in response to PHZ treatment in MKR mice. PHZ treatment also increased food intake in MKR mice; however, the fat mass was decreased and lean body mass did not change. Serum insulin, fatty acid, and triglyceride levels were not affected by PHZ treatment in MKR mice. Hyperinsulinemic-euglycemic clamp analysis demonstrated that glucose uptake in white adipose tissue was significantly increased in response to PHZ treatment. Despite the reduction in blood glucose following PHZ treatment, there was no improvement in insulin-stimulated whole-body glucose uptake in MKR mice and neither was there suppression of endogenous glucose production by insulin. These results suggest that glucotoxicity plays little or no role in the worsening of insulin resistance that occurs in the MKR mouse model of type 2 diabetes.     

CMTM2转基因小鼠的构建及其血清睾酮水平的变化

目的:建立系统性表达CMTM2的转基因小鼠模型,研究CMTM2表达对小鼠生殖系统的影响。方法:通过显微注射pRevTRE-CMTM2表达载体建立CMTM2转基因小鼠;PCR鉴定CMTM2转基因小鼠基因型;RT-PCR、Western印迹、IHC方法检测CMTM2在转基因小鼠睾丸的表达情况;放免法检测转基因小鼠血清睾酮水平。结果:成功构建高表达CMTM2蛋白的转基因小鼠,并可以稳定传代;CMTM2转基因小鼠的血清睾酮水平较野生型小鼠提高[(46.04±3.72)nmol/L vs(42.43±3.80)nmol/L,P<0.05]。结论:成功构建CMTM2高表达的转基因小鼠,初步提示CMTM2基因可能对转基因小鼠睾酮的生成和分泌有一定影响。     

Effects of noninherited maternal antigens on allotransplant rejection in a transgenic mouse model

We studied the influence of noninherited maternal antigen (NIMA) on allotransplant rejection using a mouse transgenic model. CBK transgenic (CBA [H-2k] expressing K(b) MHC class I transgene) mice were used as donors in heart transplantation experiments. Offspring of BM3.3 (CBA anti-K(b) TCR transgenic) male mice and (CBA x CBK)F1 females were used as NIMA (offspring that did not inherit K(b)) and IMA (offspring that inherited K(b) maternal antigen) recipient mice. Survival of allografts was monitored and the alloimmune response evaluated using an ELISPOT assay. IMA mice accepted CBK heart allografts and displayed no alloresponse to K(b+) cells. In contrast, mice never exposed to K(b) (offspring of BM3.3 males and CBA females) acutely rejected their grafts within 18 days posttransplantation and exhibited potent inflammatory alloresponses to K(b+) cells. NIMA mice displayed prolonged survival of allotransplants (MST >60 days). Although no deletion of anti-K(b) TCR transgenic cells was detected in these mice, they had a marked reduction in the frequency of activated alloreactive T cells producing type 1 (IFN-gamma and IL-2) cytokines and concomitant expansion of type 2 (IL-4) cytokine-secreting cells. Finally, depletion of CD4+ T cells from NIMA mice restored acute rejection of CBK hearts. This study is the first demonstration of the tolerogenic effects of NIMA on alloimmunity and allotransplant rejection in a transgenic model. It is shown that, although the NIMA tolerogenic effect is not due to deletion of alloreactive T cells, it is mediated by CD4+ T cells producing type 2 cytokines.