TLR4 inactivation protects from graft-versus-host disease after allogeneic hematopoietic stem cell transplantation

Graft-versus-host disease (GVHD) is the most common complication after hematopoietic stem cell transplantation. To clarify the role of Toll-like receptor 4 (TLR4), which is a major receptor for bacterial lipopolysaccharides (LPS), in the development of acute GVHD, we used a TLR4-knockout (TLR4^−/−) mouse GVHD model and analyzed the underlying immunological mechanisms. When TLR4^−/− mice were used as bone marrow and splenocyte cell graft donors or recipients, GVHD symptom occurrence and mortality were delayed compared to wild-type (TLR4^+/+) mice. In addition, histopathological analyses revealed that in TLR4^−/−→BALB/c chimeras, liver and small intestine tissue damage was reduced with minimal lymphocytic infiltration. In contrast to TLR4^+/+, TLR4^−/− mice dendritic cells did not express CD80, CD86, CD40, MHC-II or IL-12 during LPS induction and remained in an immature state. Furthermore, the ability of TLR4^−/− mice spleen dendritic cells to promote allogeneic T-cell proliferation and, in particular, T-helper cell 1 (Th1) development was obviously attenuated compared with TLR4^+/+ mice dendritic cells, and the levels of interferon-γ (IFN-γ) and IL-10, Th2-cell specific cytokines, were significantly higher in the serum of TLR4^−/−→BALB/c than in TLR4^+/+→BALB/c chimeric mice. Overall, our data revealed that TLR4 may play a role in the pathogenesis of GVHD and that targeted TLR4 gene therapy might provide a new treatment approach to reduce the risk of GVHD.     

MHC半相合骨髓移植后慢性GVHD小鼠模型的建立

目的建立MHC半相合异基因骨髓移植(allo-BMT)后慢性GVHD小鼠模型。方法以(Balb/c×C57BL/6)F1H-2d/b(CB6F1)雌性小鼠为受者,预处理条件为不同剂量的全身照射(TBI,60Co照射),输注MHC半相合Balb/cH-2d雄性小鼠骨髓细胞与不同数量脾细胞,观察移植后小鼠体质量变化,靶器官病理变化,血清抗ssDNA抗体、抗dsDNA抗体。结果在照射剂量为8Gy,输注骨髓细胞数量为8×106、脾细胞数量为4.5×107的小鼠至实验结束(移植后100d)全部存活,体质量减轻与对照组和其它实验组相比差异显著(P<0.05)。血清抗ssDNA抗体、抗dsDNA抗体较对照组和其它实验组显著升高(P<0.05)。该组皮肤、肝脏等病理改变明显。结论在照射剂量为8Gy,输注骨髓细胞数量为8×106、脾细胞数量为4.5×107的小鼠成功诱导出半相合allo-BMT慢性GVHD,为进一步研究慢性GVHD的发病机理、生物学特性、干预因素等打下了重要基础。     

The identification and characteristics of IL-22-producing T cells in acute graft-versus-host disease following allogeneic bone marrow transplantation

Graft-versus-host disease (GVHD) remains the major obstacle for allogeneic bone marrow transplantation, in which many proinflammatory cytokines secreted by alloreactive donor T cells are involved. Role of IL-22 as a member of IL-10 family in GVHD is still disputed and the properties of IL-22-producing cells are unclear. We demonstrated here that CD4⁺ T cells but not CD8⁺ T cells involved in GVHD were the main cellular source of donor-derived IL-22. Th1 and Th17 cells were detected not only express classical cytokine IFN-γ or IL-17, but also contributed to IL-22 secretion in GVHD. Th22 cells characterized by the independent secretion of IL-22 were identified and occupied almost half percentage of IL-22-producing CD4⁺ T cells. The frequency of IL-22-producing CD4⁺ T cells showed dynamic changes with the development of GVHD. Finally, we observed that IL-22-producing CD4⁺ T cells in GVHD mouse carried CD62L⁻CD44^high/low surface markers. In conclusion, we illuminate the characteristics of donor-derived IL-22-producing CD4⁺ T cells, which may have potent implication for further study of pathogenesis of GVHD.     

不同预处理方案对异基因骨髓移植物抗宿主病的影响

目的　建立大鼠异基因骨髓移植模型 ,应用不同的预处理方案 ,研究它们对移植物抗宿主病 (GVHD)严重程度的影响。方法　Wistar大鼠为供鼠 ,SD大鼠为受鼠 ,受鼠分 4组 ,分别予以不同的预处理方案 ,A、B组受鼠自移植前 4～ 1d ,腹腔注射氟达拉宾 (Fludarabine ,Flu) 1mg kg ,移植当天分别接受 2、6Gy的全身照射 ;C、D组受鼠在移植当天分别接受 2、6Gy的全身照射。制备供鼠骨髓细胞。照光 4h后 ,经尾静脉输注供鼠骨髓细胞 3.6× 10 7。观察各受鼠GVHD反应。结果　GVHD程度依次为 :Flu +2Gy组 <2Gy组 相似文献   

The pathology of bone marrow transplantation

Bone marrow transplantation (BMT) is increasingly being used to treat a variety of malignant and non-malignant diseases. As the toxicity of the conditioning regimen diminishes and the treatment of infection improves, graft-versus-host disease (GVHD) emerges as the main complication of allogeneic stem cell transplantation. Acute GVHD is difficult to eradicate and progression to chronic GVHD is associated with increased morbidity and mortality in long-term survivors of transplantation. GVHD primarily affects the skin, gastrointestinal tract and liver, and pathologists will be expected mainly to interpret biopsies taken from these organs. This review will therefore focus on the pathological features of GVHD with only a brief overview of other complications seen after BMT.     

Histopathology of bone marrow reconstitution after allogeneic bone marrow transplantation

In order to study haematopoietic reconstitution in allogeneic bone marrow transplantation we investigated bone marrow histology in 61 biopsies of 37 patients, treated with HLA-compatible bone marrow grafts for leukaemia or severe aplastic anaemia. The biopsies were taken from the day of transplantation until 100 d after transplantation. Stromal changes, in particular oedema, fibrosis and granulomas, were found during the whole period of observation. These changes were more prominent in biopsies from leukaemia patients than from patients with aplastic anaemia. The cellularity in the biopsies increased until 28 d after bone marrow transplantation and was stable thereafter. Initially, only clusters of cells belonging to a single cell lineage were seen, suggesting that the first outgrowth of haematopoietic cells is by proliferation of committed precursor cells. Long-lasting abnormalities in localization of haematopoietic cells in the bone marrow space and of the myeloid: erythroid ratio were seen; dyserythropoiesis was common.     

Sequential measurement of the murine acute-phase protein serum amyloid P component (SAP) as an indicator of graft-versus-host disease following allogeneic bone marrow transplantation in mice.

Murine models of bone marrow transplantation (BMT) are used commonly for studies of the pathogenesis and treatment of graft-versus-host disease (GVHD). We report here that the sequential measurement of the mouse acute-phase protein SAP can be used to provide a sensitive, quantitative index of the severity of GVHD. Thirty mice underwent allogeneic, and a further 30 syngeneic BMT. GVHD was assessed in vivo by clinical appearances and weight change, and post mortem by histology and calculation of splenic indices. Blood was obtained twice/week for SAP measurement and blood culture. In all mice an initial rise in SAP levels due to irradiation was followed by a return to baseline. Thereafter in syngeneic marrow recipients levels remained low. In contrast, after allogeneic BMT SAP levels rose progressively as mice developed GVHD, reaching a peak of 135 micrograms/ml prior to death, from a nadir at day 20 of 15 micrograms/ml. Mice with high splenic indices and histological evidence of severe GVHD had significantly higher SAP levels than mice with mild GVHD (P = 0.0002). Elevation in SAP levels occurred independently of bacteraemia. We conclude that in murine BMT sequential measurement of SAP provides an objective means of assessing GVHD in vivo.     

Contribution of Toll-like receptor signaling to germinal center antibody responses

Toll-like receptors (TLRs) have emerged as one of the most important families of innate immune receptors for initiating inflammation and also for promoting adaptive immune responses. Recent studies have examined the ability of TLRs to promote antibody responses, including T-cell-dependent antibody responses. Initial study suggested that TLR stimulation promotes primarily an extrafollicular antibody response, which rapidly produces moderate affinity antibodies made by short-lived plasma cells. Recent studies, however, have shown that TLRs can also enhance the germinal center response, which produces high affinity class-switched antibody made by long-lived plasma cells. TLR stimulation can increase the magnitude of the latter response and also enhance selection for high affinity IgG. This review summarizes recent advances in understanding the roles of TLRs in B cells and also in other cell types for enhancement of antibody responses, with an emphasis on T-cell-dependent and germinal center antibody responses.     

The pathology of bone marrow transplantation

The pathological complications of bone marrow transplantation are complex and may affect any organ in the body. The causes are often multifactorial and include the effects of chemotherapy, the conditioning regimen, drugs used in the post-transplant period such as immunosuppressants and antibiotics, graft-versus-host disease (GvHD) and the effects of the primary disease itself. Infections are common and result from the immunosuppressive effects of cytotoxic drugs and irradiation, GvHD and marrow failure. Haemorrhage is not infrequent. Graft-versws-host disease remains a significant problem and can be difficult to diagnose. Some of its histological features simulate the effects of chemo-radhtion and the diagnostic lesions may not be present early in the disease, when treatment is most effective. Evidence has accumulated that inflammatory cytokines have a key role in the pathogenesis of GvHD. It can be prevented by eliminating T-cells from the donor marrow but this procedure adversely affects marrow engraftment, increases the chances of rejection and results in a higher incidence of leukaemic relapse. Immunohistochemical staining for various cytokine-inducible molecules has led to some improvement in early diagnosis.     

小鼠异基因造血干细胞移植后使用G-CSF对aGVHD的影响

 目的: 探讨小鼠异基因造血干细胞移植(allo-HSCT)后使用粒细胞集落刺激因子(G-CSF)对急性移植物抗宿主病(aGVHD)的影响及其可能的机制。方法: 以雄性C57BL/6小鼠(H-2^b)为异基因供鼠,雄性BALB/c小鼠(H-2^d)为同基因供鼠;以接受8 Gy[⁶⁰Co] γ射线全身照射(TBI)预处理雌性BALB/c小鼠为受鼠,并随机分为7组:单纯TBI组、同基因骨髓+脾细胞移植(Syn-BMST)组、异基因骨髓移植(allo-BMT)组、异基因骨髓+脾细胞移植(allo-BMST)组、Syn-BMST后G-CSF给药(Syn-BMST+G-CSF)组、allo-BMT后G-CSF给药(allo-BMT+G-CSF)组和allo-BMST后G-CSF给药(allo-BMST+G-CSF)组,各G-CSF给药组从移植后第1天(+1 d)开始皮下注射G-CSF 2 μg/d,观察至+60 d。比较各组生存时间、aGVHD发生情况和病理改变,流式细胞术检测骨髓H2-Kb⁺细胞百分率(异基因嵌合率),比较allo-BMST和allo-BMST+G-CSF组+10 d时血清细胞因子(IL-2、IL-4、IFN-γ和TNF-α)水平、脾总有核细胞数(SpTNC)和脾细胞免疫表型的差异。结果: 单纯TBI组小鼠于照射后9~15 d死于造血衰竭,其余各组+10 d时均100%获得造血重建,随机抽取2只异基因骨髓移植受鼠,+30 d供者细胞嵌合率分别为99.8%和99.4%,表明清髓性allo-HSCT模型建立成功。Syn-BMST、Syn-BMST+G-CSF、allo-BMT和allo-BMT+G-CSF组小鼠观察至+60 d均未发生aGVHD。与allo-BMST组相比,allo-BMST+G-CSF组受鼠出现aGVHD时间早、程度重、病理改变严重、存活时间明显缩短(P<0.05)、+10 d SpTNC明显增加(P<0.05)、脾脏NK细胞显著扩增 (P<0.01)、DC1/DC2比值减低(P<0.05),而2组血清IL-2、IL-4、IFN-γ和TNF-α水平差异无统计学意义。结论: 移植后使用G-CSF对小鼠异基因单纯骨髓移植后aGVHD无明显影响,但能显著加重allo-BMST后aGVHD的严重程度并缩短受鼠生存时间,该效应可能与G-CSF诱导供鼠NK细胞扩增有关,提示临床allo-HSCT后早期使用G-CSF可能触发或加重aGVHD的风险。     

A solution to the graft-versus-host problem in bone marrow transplantation to humans

Many clinical situations arise where it would be desirable to transplant bone marrow to a marrow function deficient patient. However, bone marrow is immunologically competent by virtue of its content of lymphocyte precursors. Marrow transplantation in these patients is followed by the graft's immunological rejection of the patient — a fatal disease.A system for specific abrogation of this graft-versus-host disease after xenogeneic bone marrow transplantation to humans is presented. In this system, prospective patient cells are removed by skin biopsy for example, and injected into a fetal chimpanzee. The fetal chimpanzee becomes tolerant to this patient's antigens and will not attack or reject them when its bone marrow is removed after birth and injected into the specific patient from whom the tolerogenic cells were obtained. A simple and straightforward experimental test of this system's clinical applicability is also presented.     

Class- and subclass-specific pneumococcal antibody levels and response to immunization after bone marrow transplantation.

Immunoglobulin class- and subclass-specific antibodies to a polyvalent pneumococcal capsular polysaccharide vaccine (Pneumovax II) were measured before and after immunization in children, 1 year or more after bone marrow transplantation for a variety of genetic disorders. The median titres of specific IgG, IgG1 and IgG2 pneumococcal antibodies fell significantly (P less than 0.05) from pre-transplantation levels. The levels of pneumococcal antibodies in the patients before immunization were markedly lower than those in control children of comparable age, for antibodies of IgM, IgG, IgG1 and IgG2 classes (P = less than 0.001 in each case). Apart from IgG2 antibodies, the median response to immunization with Pneumovax II was not significantly different from the controls (P greater than 0.05). However, because of the lower pre-immunization levels, the patients did not achieve a high post-immunization-specific antibody titre in any immunoglobulin class or subclass, when compared with normal children. Neither the pre-immunization specific antibody levels nor the response to immunization were affected by splenectomy or the presence of chronic graft-versus-host disease. Immunization of the donor before bone marrow harvest did not influence the level of specific antibody 1 year or more after transplantation. No significant correlation was found between the total serum IgG2, the patients' age at the time of assessment, or time after transplantation, and the IgG2-specific antibody response. The lack of specific antibodies and the poor IgG2 response to pneumococcal antigens may contribute towards the occurrence of infection with Streptococcus pneumoniae in the late post-transplantation period.     

异基因骨髓移植小鼠免疫功能缺损机制的探讨

异基因骨髓移植(Allogeneic Bone Marrow Transplantation,ABMT)后,受体的免疫功能长期缺损,是患者术后极易感染死亡的重要原因之一.本文对ABMT小鼠(C57BL/6→BALB/c)免疫功能缺损的机制进行了探讨,发现ABMT小鼠IL-2产生明显受损;其脾细胞与(C57BL/6小鼠脾细胞一起过继转移到致死量照射的BALB/C小鼠体内,能抑制移植物抗宿主病(GVHD)的发生.去除其脾T细胞后,这种抑制作用丧失,ABMT小鼠脾细胞上清中发现一种非特异的抑制因子,能抑制正常小鼠脾细胞产生混合淋巴细胞反应的能力;能抑制正常小鼠的脾细胞产生IL-2;抑制正常小鼠脾细胞毒T淋巴细胞(CTL)的杀伤活性.用抗Thy-1.2单抗和补体去除ABMT小鼠脾T细胞后,其脾细胞培养上(?)的上述抑制活性丧失.这说明ABMT小鼠脾T(?)细胞活性增强是其免疫功能缺损的重要原因之一,它通过释放非特异的抑制因子执行其免疫抑制功能.     

Antibacterial polysaccharide antibody deficiency after allogeneic bone marrow transplantation

Allogeneic bone marrow-engrafted adults immunized with meningococcal types A and C and pneumococcal type 14 polysaccharide antigens showed only low antibody titers of the IgM class, no antibody titers of the IgG or IgA classes, and no bactericidial activityin vitro. The analytical isoelectrofocusing showed the appearance of a restricted pattern of clonotypes in a minority of subjects. These observations are consistent with the hypothesis that B cells in bone marrow transplant patients express some characteristics of neonatal B cells and suggest that polysaccharide-protein conjugates, rather than isolated polysaccharide, might be utilized in the setting of bone marrow transplantation.     

单元型相同骨髓移植后患者单核细胞来源的DC表面分子的检测

对单元型相同骨髓移植患者造血重建后的外周血单个核细胞加GM-CSF、IL-4进行DC诱导,7d后加入TNF-α于培养DC中,继续诱导3d。测定DC的表型、混合淋巴细胞反应对T细胞增殖能力的测定,并与健康志愿者外周血来源的DC进行比较。探讨单元型相同造血干细胞移植后患者单个核细胞来源的DC的生物学特性。结果显示,单元型相同造血干细胞移植患者外周血单个核细胞和正常人外周血单个核细胞来源的DC均高表达CD1α、CD83、CD80、CD86和HLA-DR等DC的相关抗原和共刺激分子,患者的未成熟DC经TNF-α诱导后,成为成熟和有功能的DC,单元型相同造血干细胞移植患者单个核细胞来源的DC在体外具有激发同种异体外周血T细胞增殖的能力,与健康人外周血来源DC组相比均无统计学意义(P>0.05)。     

Cellular composition of the spleen after human allogeneic bone marrow transplantation

The cellular composition of the spleen has been assessed in 18 patients who died 15-326 days after receiving allogeneic marrow for leukaemia. The white pulp showed marked lymphocyte depletion with no germinal centres, very few B cells, and rare plasma cells. The marginal zone was unrecognizable but there were moderate numbers of T cells in the periarteriolar lymphatic sheaths (PALS), showing great variation in CD4/CD8 ratio. The percentage of CD4+ cells decreased with time post transplant. CD8+ cells were reduced in patients with graft-versus-host disease (GvHD) who also showed no increase in cells staining for activation markers. No T cells were detected expressing immature phenotypes and no differences were detected between patients who received marrow purged or unpurged of T cells. Macrophage numbers appeared normal. Extramedullary haemopoiesis (EMH) was predominantly in the red pulp greater than 30 days after transplantation but more commonly in the white pulp before then. Pyknotic cells were common in seven cases and appeared to be associated with EMH rather than GvHD. Chimaeric studies demonstrated small numbers of donor cells in the PALS at 26 days and larger numbers at 56 days.     

Cellular responses to bacterial cell wall components are mediated through MyD88-dependent signaling cascades

MyD88 is an adaptor molecule essential for signaling via the Toll-like receptor (TLR)/IL-1 receptor family. TLR4 is a member of the TLR family and a point mutation in the Tlr4 gene causes hyporesponsiveness to lipopolysaccharide (LPS) in C3H/HeJ mice. We have previously shown that both TLR4- and MyD88-deficient mice are hyporesponsive to LPS. In this study we examined the responsiveness of these two knockout mice to various bacterial cell wall components. Cells from TLR4-deficient mice responded to several kinds of LPS, peptidoglycan and crude cell wall preparation from Gram-positive bacteria and mycobacterial lysates. In contrast, macrophages and splenocytes from MyD88-deficient mice did not respond to any of the bacterial components we tested. These results show that MyD88 is essential for the cellular response to bacterial cell wall components.     

Bone marrow-derived mesenchymal stem cells decrease acute graft-versus-host disease after allogeneic hematopoietic stem cells transplantation

Graft-versus-host disease is a major complication of allogeneic hematopoietic stem cells transplantation, leading to serious morbidity and mortality. Mesenchymal stem cells(MSC)from bone marrow cause immunoregulation in vitro and in vivo. They also have the potential to protect from lethal GVHD after both autologous and allogeneic Hematopoietic Stem Cells Transplantation (HSCT). In this study, we investigated the mechanisms responsible for GVHD in the allo-HSCT co-transplantation with MSC condition. The model of acute GVHD in Rats was established using allogeneic HSC with donor-derived T cells transplantation, with or without additional donor-derived MSC co-transplantation. The degrees of GVHD were compared, the differentiation of CD4⁺, CD8⁺, Th1/Th2 and CD4⁺CD25⁺ T cells in vivo were assessed by flow cytometry and RT-PCR analyses. We found that MSC inhibited lethal GVHD after allo-HSCT. The value of CD8⁺ and CD4⁺ T cells and the ratio of Th1/Th2 T cell subsets decreased, at the same time the proportion of CD4⁺CD25⁺ T cells increased both in spleen lymphocytes and thymocytes in vivo after allo-HSCT with MSC co-transplantation compared with conventional allo-HSCT. Our results strongly suggested that BM-derived MSC has the function of preventing lethal GVHD after allo-HSCT by means of homeostasis of T subsets in vivo.     

IgG subclass levels and immune reconstitution after T cell-depleted allogeneic bone marrow transplantation

Defects of humoral immunity are well documented after bone marrow transplantation (BMT). Immunoglobulin recovery can be impaired and selective deficiencies of IgG subclasses have been reported. The nature of these deficiencies may reflect patterns of infection in the post-BMT period. We studied immunoglobulin and IgG subclass recovery in 20 long term (greater than 100 days) survivors of T depleted allogeneic BMT. Although there was no fall in mean levels of IgG, IgM or IgA for the patient group, 14 patients (70%) developed a deficiency of one or more immunoglobulin isotype at some stage post-BMT. Eight patients (40%) had deficiency of IgG, IgA and IgM and six had selective deficiencies. When IgG subclasses were measured it was seen that mean levels of IgG2 and IgG4 fell post-BMT with trough levels occurring at around 120 days post-transplant. Sixty per cent of patients developed IgG2 subclass deficiency and of these patients 78% had an associated IgG4 deficiency. Deficiencies of IgG1 and IgG3 were less common and less prolonged than those of IgG2 and IgG4; in addition, mean levels of IgG1 and IgG3 showed a rise early post-BMT. In conclusion, a majority of our patients developed immunoparesis following BMT, usually at around 120 days after transplantation. IgG2 subclass deficiency, often in association with IgG4 deficiency, is common and may occur despite normal total IgG levels. Deficiencies of immunoglobulin and IgG subclasses may persist for longer than 1 year post-BMT. Differing profiles of immunoglobulin and IgG subclass recovery may help dictate patterns of infection in long-term survivors of BMT.     

Harvest of human bone marrow directly from bone

Harvest of human bone marrow directly from freshly resected bone provides purer preparations of marrow than can be obtained by the conventional technique of multiple aspirations from the iliac crests. In particular, directly harvested marrow is much less heavily contaminated with peripheral blood lymphocytes, a known source of mature T cells. Because of the possible relevance of these contaminating T cells for cadaveric bone marrow transplants, the best source of human marrow harvested directly from bone has been studied. Human bone marrow was harvested from 46 surgical specimens and 9 cadaveric tissue donors. Vertebral bodies provided the best source of bone marrow with average yields of 3.1 ± 1.6 × 10⁹ cells per vertebra. When entire ilia were removed and processed for marrow, an average of 1.6 ± 1.0 × 10⁹ cells was obtained. Surgically resected ribs yielded lower amounts of marrow with a mean cell number of 3.2 ± 2.6 × 10⁸ per rib. Isolation of bone marrowb mononuclear cells from these preparations by density gradient centrifugation resulted in a loss of 45% of the starting cells. Human bone marrow was found to contain 5–6% T cells before gradient separation and these cells were immunologically competent as measured in vitro by responses to mitogens and alloantigens. This technique may be useful in obtaining human bone marrow for both immunologic studies and allogeneic transplantation.