In vivo expansion of co-transplanted T cells impacts on tumor re-initiating activity of human acute myeloid leukemia in NSG mice.

Human cells from acute myeloid leukemia (AML) patients are frequently transplanted into immune-compromised mouse strains to provide an in vivo environment for studies on the biology of the disease. Since frequencies of leukemia re-initiating cells are low and a unique cell surface phenotype that includes all tumor re-initiating activity remains unknown, the underlying mechanisms leading to limitations in the xenotransplantation assay need to be understood and overcome to obtain robust engraftment of AML-containing samples. We report here that in the NSG xenotransplantation assay, the large majority of mononucleated cells from patients with AML fail to establish a reproducible myeloid engraftment despite high donor chimerism. Instead, donor-derived cells mainly consist of polyclonal disease-unrelated expanded co-transplanted human T lymphocytes that induce xenogeneic graft versus host disease and mask the engraftment of human AML in mice. Engraftment of mainly myeloid cell types can be enforced by the prevention of T cell expansion through the depletion of lymphocytes from the graft prior transplantation.

The shortest isoform of C/EBPß, liver inhibitory protein (LIP), collaborates with Evi1 to induce AML in a mouse BMT model.

Ecotropic viral integration site 1 (Evi1) is one of the master regulators in the development of acute myeloid leukemia (AML) and myelodysplastic syndrome. High expression of Evi1 is found in 10% of patients with AML and indicates a poor outcome. Several recent studies have indicated that Evi1 requires collaborative factors to induce AML. Therefore, the search for candidate factors that collaborate with Evi1 in leukemogenesis is one of the key issues in uncovering the mechanism of Evi1-related leukemia. Previously, we succeeded in making a mouse model of Evi1-related leukemia using a bone marrow transplantation (BMT) system. In the Evi1-induced leukemic cells, we identified frequent retroviral integrations near the CCAAT/enhancer-binding protein ß (C/EBPß) gene and overexpression of its protein. These findings imply that C/EBPß is a candidate gene that collaborates with Evi1 in leukemogenesis. Cotransduction of Evi1 and the shortest isoform of C/EBPß, liver inhibitory protein (LIP), induced AML with short latencies in a mouse BMT model. Overexpression of LIP alone also induced AML with longer latencies. However, excision of all 3 isoforms of C/EBPß (LAP*/LAP/LIP) did not inhibit the development of Evi1-induced leukemia. Therefore, isoform-specific intervention that targets LIP is required when we consider C/EBPß as a therapeutic target.

Post-bone-marrow-transplant leukemia cutis.

Granulocytic sarcoma or chloroma is a tumor of immature cells from the granulocyte line that is generally associated with acute myeloid leukemia. The skin is one of the most affected organs. This lesion may complicate hematological dyscrasias, which is generally indicative of a poor prognosis. We present a case of a 51-year-old patient who was diagnosed with acute myeloid leukemia with a complex karyotype that debuted with a post-transplant cutaneous and hematological relapse, a very rare occurrence in the literature given that no extramedullary involvement was present prior to the transplant.

CD4+ T cell-depleted lymphocyte infusion impairs neither the recovery of recipient thymus nor the development of transplanted thymus.

Thymus transplantation, in conjunction with bone marrow transplantation (BMT), has been attracting attention for the treatment of various diseases. Recently, donor lymphocyte infusion (DLI) has been used as a helpful tool for establishing donor chimerism and preventing a relapse of leukemia/lymphoma. However, the effects of DLI on transplanted and recipient thymuses have not been explored. We therefore performed DLI in the intrabone marrow-BMT + thymus transplantation setting. We have found that DLI leads to derangements in both recipient thymuses and transplanted thymuses; by 2 wk after BMT, we saw a decrease in total cell number, a lower percentage of CD4(+)CD8(+) cells, and the obliteration of the thymic corticomedullary junction. Four weeks later, the thymic impairment became more serious. However, when we depleted the CD4(+) T cells (CD4(-)-DLI), the recipient thymic recovery and transplanted thymic development were significantly restored by the treatment. In addition, there were much greater levels of TNF-α and Fas ligand, and a lower percentage of regulatory T cells in the DLI group than in the CD4(-)-DLI group. These findings indicate that inflammation induced by DLI, especially by CD4(+) T cells, plays a crucial role in the thymic impairment.

Adoptive transfer of Tc1 or Tc17 cells elicits antitumor immunity against established melanoma through distinct mechanisms.

Adoptive cell transfer (ACT) of ex vivo-activated autologous tumor-reactive T cells is currently one of the most promising approaches for cancer immunotherapy. Recent studies provided some evidence that IL-17-producing CD8(+) (Tc17) cells may exhibit potent antitumor activity, but the specific mechanisms have not been completely defined. In this study, we used a murine melanoma lung-metastasis model and tested the therapeutic effects of gp100-specific polarized type I CD8(+) cytotoxic T (Tc1) or Tc17 cells combined with autologous bone marrow transplantation after total body irradiation. Bone marrow transplantation combined with ACT of antitumor (gp100-specific) Tc17 cells significantly suppressed the growth of established melanoma, whereas Tc1 cells induced long-term tumor regression. After ACT, Tc1 cells maintained their phenotype to produce IFN-γ, but not IL-17. However, although Tc17 cells largely preserved their ability to produce IL-17, a subset secreted IFN-γ or both IFN-γ and IL-17, indicating the plasticity of Tc17 cells in vivo. Furthermore, after ACT, the Tc17 cells had a long-lived effector T cell phenotype (CD127(hi)/KLRG-1(low)) as compared with Tc1 cells. Mechanistically, Tc1 cells mediated antitumor immunity primarily through the direct effect of IFN-γ on tumor cells. In contrast, despite the fact that some Tc17 cells also secreted IFN-γ, Tc17-mediated antitumor immunity was independent of the direct effects of IFN-γ on the tumor. Nevertheless, IFN-γ played a critical role by creating a microenvironment that promoted Tc17-mediated antitumor activity. Taken together, these studies demonstrate that both Tc1 and Tc17 cells can mediate effective antitumor immunity through distinct effector mechanisms, but Tc1 cells are superior to Tc17 cells in mediating tumor regression.

Genetic deletion of chemokine receptor Ccr7 exacerbates atherogenesis in ApoE-deficient mice.

AIMS: Recent evidence suggests that both Ccr7 and its ligands, Ccl19 and Ccl21, are present in mouse and human atherosclerotic plaques; however, the role of Ccr7 in atherogenesis is still controversial. Here, we addressed this question by using the classic apolipoprotein E-deficient (ApoE(-/-)) mouse model of atherosclerosis. METHODS AND RESULTS: Ccr7(-/-)ApoE(-/-) double knockout mice and Ccr7(+/+)ApoE(-/-) littermates were generated and maintained on a high-fat Western diet for 8 weeks to induce atherosclerosis. Ccr7(-/-)ApoE(-/-) mice showed an ~80% increase in atherosclerotic lesion size in the whole aorta and a two-fold increase in the aortic root compared with Ccr7(+/+)ApoE(-/-) mice. Ccr7(-/-)ApoE(-/-) mice had increased T cells in the blood, bone marrow, and spleen, as well as in atherosclerotic lesions. Competitive repopulation experiments revealed that T cells from Ccr7(-/-)ApoE(-/-) mice migrated poorly into lymph nodes but better into mouse aortas compared with T cells from Ccr7(+/+)ApoE(-/-) mice. Transplantation of the bone marrow from Ccr7(-/-)ApoE(-/-) mice into lethally irradiated Ccr7(+/+)ApoE(-/-) mice resulted in ~60% more atherosclerotic lesions compared with Ccr7(+/+)ApoE(-/-) donor bone marrow, suggesting that exacerbation was mediated by a Ccr7(+) bone marrow-derived cell(s). Furthermore, in Ccr7(-/-)ApoE(-/-) mice the serum level of IL-12 was markedly increased, whereas the level of transforming growth factor beta (TGF-ß) was significantly decreased, suggesting an imbalance of T cell responses in these mice. CONCLUSION: Our data suggest that genetic deletion of Ccr7 exacerbates atherosclerosis by increasing T cell accumulation in atherosclerotic lesions.

Unraveling graft-versus-host disease and graft-versus-leukemia responses using TCR Vß spectratype analysis in a murine bone marrow transplantation model.

The optimum use of allogeneic blood and marrow transplantation (BMT) as a curative therapy for hematological malignancies lies in the successful separation of mature donor T cells that are host reactive and induce graft-versus-host disease (GVHD) from those that are tumor reactive and mediate graft-versus-leukemia (GVL) effects. To study whether this separation was possible in an MHC-matched murine BMT model (B10.BR→CBA) with a CBA-derived myeloid leukemia line, MMC6, we used TCR Vß CDR3-size spectratype analysis to first show that the Vß13 family was highly skewed in the B10.BR anti-MMC6 CD8(+) T cell response but not in the alloresponse against recipient cells alone. Transplantation of CD8(+)Vß13(+) T cells at the dose equivalent of their constituency in 1 × 10(7) CD8(+) T cells, a dose that had been shown to mediate lethal GVHD in recipient mice, induced a slight GVL response with no concomitant GVHD. Increasing doses of CD8(+)Vß13(+) T cells led to more significant GVL responses but also increased GVHD symptoms and associated mortality. Subsequent spectratype analysis of GVHD target tissues revealed involvement of gut-infiltrating CD8(+)Vß13(+) T cells accounting for the observed in vivo effects. When BMT recipients were given MMC6-presensitized CD8(+)Vß13(+) T cells, they displayed a significant GVL response with minimal GVHD. Spectratype analysis of tumor-presensitized, gut-infiltrating CD8(+)Vß13(+) T cells showed preferential usage of tumor-reactive CDR3-size lengths, and these cells expressed increased effector memory phenotype (CD44(+)CD62L(-/lo)). Thus, Vß spectratyping can identify T cells involved in antihost and antitumor reactivity and tumor presensitization can aid in the separation of GVHD and GVL responses.

Experimental evidence of cell dissemination playing a role in pathogenesis of IgA nephropathy in multiple lymphoid organs.

BACKGROUND: Since the pathogenesis of immunoglobulin A (IgA) nephropathy (IgAN) remains unclear, the rationale for current IgAN therapies is still obscure. Recent studies have shown that galactose-deficient IgA1 (GdIgA1) plays a critical role in the pathogenesis of IgAN and can be a non-invasive IgAN biomarker, although the origin of the pathogenic cells producing GdIgA1 is unknown. We examined the cell types and localization of pathogenic cells in IgAN-prone mice. METHODS: We transplanted bone marrow (BM) or spleen cells with or without specific cell types from IgAN-prone mice, which have many features similar to human IgAN, to identify cell types responsible for the IgAN phenotype and to determine their localization. RESULTS: BM transplantation and whole spleen cell transfer from IgAN-prone mice reconstituted IgAN in normal and severe combined immunodeficiency mice. Depletion of CD90(+) spleen cells had no affect on reconstitution, whereas CD19(+) B cells from the spleen were sufficient to reconstitute IgAN in both recipients. CONCLUSIONS: These results indicate that CD19(+) B cells, which can regulate nephritogenic IgA production in a T-cell-independent manner, are responsible for the disease and are disseminated in peripheral lymphoid organs.

Post-transplantation B cell function in different molecular types of SCID.

PURPOSE: Severe combined immunodeficiency (SCID) is a syndrome of diverse genetic cause characterized by profound deficiencies of T, B and sometimes NK cell function. Non-ablative HLA-identical or rigorously T cell-depleted haploidentical parental bone marrow transplantation (BMT) results in thymus-dependent genetically donor T cell development in the recipients, leading to a high rate of long-term survival. However, the development of B cell function has been more problematic. We report here results of analyses of B cell function in 125 SCID recipients prior to and long-term after non-ablative BMT, according to their molecular type. METHODS: Studies included blood immunoglobulin measurements; antibody titers to standard vaccines, blood group antigens and bacteriophage Φ X 174; flow cytometry to examine for markers of immaturity, memory, switched memory B cells and BAFF receptor expression; B cell chimerism; B cell spectratyping; and B cell proliferation. RESULTS: The results showed that B cell chimerism was not required for normal B cell function in IL7Rα-Def, ADA-Def and CD3-Def SCIDs. In X-linked-SCID, Jak3-Def SCID and those with V-D-J recombination defects, donor B cell chimerism was necessary for B cell function to develop. CONCLUSION: The most important factor determining whether B cell function develops in SCID T cell chimeras is the underlying molecular defect. In some types, host B cells function normally. In those molecular types where host B cell function did not develop, donor B cell chimerism was necessary to achieve B cell function. 236 words.

Colon neoplastic cells do not originate from bone marrow-derived cells after sex-mismatched bone marrow transplantation.

BACKGROUND: Although previous studies indicate that gastrointestinal (GI) cancer may originate from cells recruited from bone marrow (BM) in mice, whether similar phenomena occur in humans is controversial. In the current study, we evaluated two female patients who developed colonic adenocarcinoma more than 10 years after gender-mismatched BM transplantation, and followingly underwent successful endoscopic mucosal resection. MATERIALS AND METHODS: Fluorescent in situ hybridization (FISH) analysis was used to determine whether the tumours contained donor-derived BM cells. RESULTS: Approximately 1.2% of the tumour cells contained Y-chromosome-positive signals, and a comparable percentage of normal colonic epithelial cells close to the tumour also contained Y-chromosome-positive signals. CONCLUSION: These results do not support the concept that GI cancer can originate from BM-derived cells.

CD8+ Foxp3+ regulatory T cells are induced during graft-versus-host disease and mitigate disease severity.

Regulatory T cells (Tregs), in particular CD4(+) Foxp3(+) T cells, have been shown to play an important role in the maintenance of tolerance after allogeneic stem cell transplantation. In the current study, we have identified a population of CD8(+) Foxp3(+) T cells that are induced early during graft-versus-host disease (GVHD), constitute a significant percentage of the entire Treg population, and are present in all major GVHD target organs. These cells expressed many of the same cell surface molecules as found on CD4(+) Tregs and potently suppressed in vitro alloreactive T cell responses. Induction of these cells correlated positively with the degree of MHC disparity between donor and recipient and was significantly greater than that observed for CD4(+)-induced Tregs (iTregs) in nearly all tissue sites. Mice that lacked the ability to make both CD8(+) and CD4(+) iTregs had accelerated GVHD mortality compared with animals that were competent to make both iTreg populations. The absence of both iTreg populations was associated with significantly greater expansion of activated donor T cells and increased numbers of CD4(+) and CD8(+) T cells that secreted IFN-γ and IL-17. The presence of CD8(+) iTregs, however, was sufficient to prevent increased GVHD mortality in the complete absence of CD4(+) Tregs, indicating at least one functional iTreg population was sufficient to prevent an exacerbation in GVHD severity, and that CD8(+) iTregs could compensate for CD4(+) iTregs. These studies define a novel population of CD8(+) Tregs that play a role in mitigating the severity of GVHD after allogeneic stem cell transplantation.

Polyinosinic-polycytidylic acid limits tumor outgrowth in a mouse model of metastatic lung cancer.

Polyinosinic-polycytidylic acid (poly I:C), a TLR3 ligand, is currently being tested in human clinical trials as an adjuvant to anti-cancer vaccines and in combination with other therapies. However, little is known about its activity in established pulmonary metastasis. The aim of our study was to elucidate the effect of poly I:C (1, 10, or 100 µg/mouse) in a mouse model of B16-F10-induced metastatic lung cancer. Lung tumor growth was arrested after a single administration of poly I:C. This was associated with higher influx of mature dendritic cells (DCs), which drove toward a Th1-like, Th17-like, and cytotoxic immune environment. The interference with IFN type I receptor signaling by means of a specific mAb reversed poly I:C-mediated tumor regression due to lower presence of myeloid DCs, cytotoxic DCs (CD11c(+)CD8(+)), NKT cells, CD8(+) T cells, and Th1-like cytokines. Moreover, the adoptive transfer of poly I:C-activated bone marrow-derived DCs into tumor-bearing mice resulted in activities similar to those of the systemic administration of poly I:C on lung tumor burden. In conclusion, our data prove that poly I:C has potential anti-tumor activity in a mouse model of established pulmonary metastasis. The activation of DCs and the production of IFN type I are responsible for an effective T cytotoxic immune response against metastatic lung cancer progression after poly I:C treatment.

Novel role for surfactant protein A in gastrointestinal graft-versus-host disease.

Graft-versus-host disease (GVHD) is a severe and frequent complication of allogeneic bone marrow transplantation (BMT) that involves the gastrointestinal (GI) tract and lungs. The pathobiology of GVHD is complex and involves immune cell recognition of host Ags as foreign. We hypothesize a central role for the collectin surfactant protein A (SP-A) in regulating the development of GVHD after allogeneic BMT. C57BL/6 (H2b; WT) and SP-A-deficient mice on a C57BL/6 background (H2b; SP-A(-/-)) mice underwent allogeneic or syngeneic BMT with cells from either C3HeB/FeJ (H2k; SP-A-deficient recipient mice that have undergone an allogeneic BMT [SP-A(-/-)alloBMT] or SP-A-sufficient recipient mice that have undergone an allogeneic BMT) or C57BL/6 (H2b; SP-A-deficient recipient mice that have undergone a syngeneic BMT or SP-A-sufficient recipient mice that have undergone a syngeneic BMT) mice. Five weeks post-BMT, mice were necropsied, and lung and GI tissue were analyzed. SP-A(-/-) alloBMT or SP-A-sufficient recipient mice that have undergone an allogeneic BMT had no significant differences in lung pathology; however, SP-A(-/-)alloBMT mice developed marked features of GI GVHD, including decreased body weight, increased tissue inflammation, and lymphocytic infiltration. SP-A(-/-)alloBMT mice also had increased colon expression of IL-1ß, IL-6, TNF-α, and IFN-γ and as well as increased Th17 cells and diminished regulatory T cells. Our results demonstrate the first evidence, to our knowledge, of a critical role for SP-A in modulating GI GVHD. In these studies, we demonstrate that mice deficient in SP-A that have undergone an allogeneic BMT have a greater incidence of GI GVHD that is associated with increased Th17 cells and decreased regulatory T cells. The results of these studies demonstrate that SP-A protects against the development of GI GVHD and establishes a role for SP-A in regulating the immune response in the GI tract.

Arsenic trioxide prevents murine sclerodermatous graft-versus-host disease.

Chronic graft-versus-host disease (GVHD) follows allogeneic hematopoietic stem cell transplantation. It results from alloreactive processes induced by minor MHC incompatibilities triggered by activated APCs, such as plasmacytoid dendritic cells (pDCs), and leading to the activation of CD4 T cells. Therefore, we tested whether CD4(+) and pDCs, activated cells that produce high levels of reactive oxygen species, could be killed by arsenic trioxide (As(2)O(3)), a chemotherapeutic drug used in the treatment of acute promyelocytic leukemia. Indeed, As(2)O(3) exerts its cytotoxic effects by inducing a powerful oxidative stress that exceeds the lethal threshold. Sclerodermatous GVHD was induced in BALB/c mice by body irradiation, followed by B10.D2 bone marrow and spleen cell transplantation. Mice were simultaneously treated with daily i.p. injections of As(2)O(3). Transplanted mice displayed severe clinical symptoms, including diarrhea, alopecia, vasculitis, and fibrosis of the skin and visceral organs. The symptoms were dramatically abrogated in mice treated with As(2)O(3). These beneficial effects were mediated through the depletion of glutathione and the overproduction of H(2)O(2) that killed activated CD4(+) T cells and pDCs. The dramatic improvement provided by As(2)O(3) in the model of sclerodermatous GVHD that associates fibrosis with immune activation provides a rationale for the evaluation of As(2)O(3) in the management of patients affected by chronic GVHD.

Tumor-expressed inducible nitric oxide synthase controls induction of functional myeloid-derived suppressor cells through modulation of vascular endothelial growth factor release.

Inducible NO synthase (iNOS) is a hallmark of chronic inflammation that is also overexpressed in melanoma and other cancers. Whereas iNOS is a known effector of myeloid-derived suppressor cell (MDSC)-mediated immunosuppression, its pivotal position at the interface of inflammation and cancer also makes it an attractive candidate regulator of MDSC recruitment. We hypothesized that tumor-expressed iNOS controls MDSC accumulation and acquisition of suppressive activity in melanoma. CD11b(+)GR1(+) MDSC derived from mouse bone marrow cells cultured in the presence of MT-RET-1 mouse melanoma cells or conditioned supernatants expressed STAT3 and reactive oxygen species (ROS) and efficiently suppressed T cell proliferation. Inhibition of tumor-expressed iNOS with the small molecule inhibitor L-NIL blocked accumulation of STAT3/ROS-expressing MDSC, and abolished their suppressive function. Experiments with vascular endothelial growth factor (VEGF)-depleting Ab and recombinant VEGF identified a key role for VEGF in the iNOS-dependent induction of MDSC. These findings were further validated in mice bearing transplantable MT-RET-1 melanoma, in which L-NIL normalized elevated serum VEGF levels; downregulated activated STAT3 and ROS production in MDSC; and reversed tumor-mediated immunosuppression. These beneficial effects were not observed in iNOS knockout mice, suggesting L-NIL acts primarily on tumor- rather than host-expressed iNOS to regulate MDSC function. A significant decrease in tumor growth and a trend toward increased tumor-infiltrating CD8(+) T cells were also observed in MT-RET transgenic mice bearing spontaneous tumors. These data suggest a critical role for tumor-expressed iNOS in the recruitment and induction of functional MDSC by modulation of tumor VEGF secretion and upregulation of STAT3 and ROS in MDSC.

Tissue-resident ecto-5' nucleotidase (CD73) regulates leukocyte trafficking in the ischemic brain.

Ectoenzymes expressed on the surface of vascular cells and leukocytes modulate the ambient nucleotide milieu. CD73 is an ecto-5' nucleotidase that catalyzes the terminal phosphohydrolysis of AMP and resides in the brain on glial cells, cells of the choroid plexus, and leukocytes. Though CD73 tightens epithelial barriers, its role in the ischemic brain remains undefined. When subjected to photothrombotic arterial occlusion, CD73(-/-) mice exhibited significantly larger (49%) cerebral infarct volumes than wild-type mice, with concordant increases in local accumulation of leukocyte subsets (neutrophils, T lymphocytes, macrophages, and microglia). CD73(-/-) mice were rescued from ischemic neurologic injury by soluble 5'-nucleotidase. In situ, CD73(-/-) macrophages upregulated expression of costimulatory molecules far more than wild-type macrophages, with a sharp increase of the CD80/CD86 ratio. To define the CD73-bearing cells responsible for ischemic cerebroprotection, mice were subjected to irradiative myeloablation, marrow reconstitution, and then stroke following engraftment. Chimeric mice lacking CD73 in tissue had larger cerebral infarct volumes and more tissue leukosequestration than did mice lacking CD73 on circulating cells. These data show a cardinal role for CD73 in suppressing ischemic tissue leukosequestration. This underscores a critical role for CD73 as a modulator of brain inflammation and immune function.

Regulatory T-cell subset analysis and profile of interleukin (IL)-10, IL-17 and interferon-gamma cytokine-producing cells in kidney allograft recipients with donor cells infusion.

BACKGROUND: This pilot study aimed to assess whether the perioperative infusion of donor bone marrow cells (DBMC) in renal allograft recipients can affect the appearance of peripheral regulatory T-cell subsets and the profile of cytokine-producing cells [interferon-gamma (IFN-γ), interleukin (IL)-17 and IL-10] 2 years after transplantation. METHODS: Fresh blood samples were collected from 14 kidney recipients who received infusion and from 13 kidney recipients without infusion who served as controls at the end of the second post-transplantation year. Initially the percentages of CD4(+)CD25(+)FoxP3(+) T cells and CD3(+)CD8(+)CD28(-) T cells were quantified using flowcytometry. Thereafter, the frequencies of IL-10-, IL-17- and IFN-γ-producing cells were determined separately using the ELISPOT technique with peptides corresponding to mismatched donor HLA-DR molecules and phytohemagglutinin (PHA). RESULTS: The mean numbers of IFN-γ- and IL-17-producing cells in response to PHA were lower in infused patients than in controls (P = 0.02 and P = 0.18, respectively); however, an increased frequency of IL-10-producing cells was observed compared to controls (P = 0.07). Furthermore, the ratio of IL-10/IFN-γ-producing cells was significantly higher in the DBMC-infused group versus controls (P = 0.01). There was a negative correlation between the percentage of CD3(+)CD8(+)CD28(-)T cells and IL-17-producing cells in the infused group (r = -0.539, P = 0.04). The mean levels and the frequency of microchimerism within the first post-transplantation year were also significantly higher in infused patients than in controls (P = 0.007 and P = 0.001, respectively). CONCLUSION: Our findings suggest that DBMC infusion could partially stimulate the regulatory mechanisms against alloimmune responses in kidney allograft recipients

Posterior reversible encephalopathy syndrome.

Posterior reversible encephalopathy syndrome (PRES) is characterized by headache, altered mental status, visual disturbances, and seizures. Radiological features typically include edema of the posterior cerebral regions, especially of the parietooccipital lobes. Atypical imaging features, such as involvement of anterior cerebral regions, deep white matter, and the brain stem are also frequently seen. Vasoconstriction is common in vascular imaging. Different conditions have been associated with PRES, but toxemia of pregnancy, solid organ or bone marrow transplantation, immunosuppressive treatment, cancer chemotherapy, autoimmune diseases, and hypertension are most commonly described. The pathophysiology of PRES is unclear and different hypotheses are being discussed. Posterior reversible encephalopathy syndrome is best managed by monitoring and treatment in the setting of a neurointensive care unit. The prognosis is usually benign with complete reversal of clinical symptoms within several days, when adequate treatment is immediately initiated. Treatment of severe hypertension, seizures, and withdrawal of causative agents represent the hallmarks of specific therapy in PRES. Delay in diagnosis and treatment may lead to permanent neurological sequelae. Therefore, awareness of PRES is of crucial importance for the intensivist.

Endothelial and epithelial barriers in graft-versus-host disease.

Endothelial and epithelial cells form selectively permeable barriers that separate tissue compartments. These cells coordinate movement between the lumen and tissue via the transcellular and paracellular pathways. The primary determinant of paracellular permeability is the tight junction, which forms an apical belt-like structure around endothelial and epithelial cells. This chapter discusses endothelial and epithelial barriers in graft-versus-host disease after allogeneic bone marrow transplantation, with a focus on the tight junction and its role in regulating paracellular permeability. Recent studies suggest that in graft-versus-host disease, pathological increases in paracellular permeability, or barrier dysfunction, are initiated by pretransplant conditioning and sustained by alloreactive cells and the proinflammatory milieu. The intestinal epithelium is a significant focus, as it is a target organ of graft-versus-host disease, and the mechanisms of barrier regulation in intestinal epithelium have been well characterized. Finally, we propose a model that incorporates endothelial and epithelial barrier dysfunction in graft-versus-host disease and discuss modulating barrier properties as a therapeutic approach.

Transplantation of bone marrow mononuclear cells decreases seizure incidence, mitigates neuronal loss and modulates pro-inflammatory cytokine production in epileptic rats.

Approximately 30% of patients with mesial temporal lobe epilepsy do not respond to treatment with antiepileptic drugs. We have previously shown that transplantation of mononuclear bone marrow cells (BMC) has an anticonvulsant effect in acute epilepsy. Here, we used pilocarpine to induce epilepsy in rats and studied the effects of BMC injected intravenously either at the onset of seizures or after 10 months of recurrent seizures. BMC effectively decreased seizure frequency and duration. In addition, decreased levels of proinflammatory cytokines (TNF-α, IL-1ß and IL-6) and increased levels of anti-inflammatory cytokine (IL-10) were observed in the brain and serum of BMC-treated rats. Transplants performed at seizure-onset protected against pilocarpine-induced neuronal loss and gliosis and stimulated the proliferation of new neurons in epileptic rats. Our data demonstrate that BMC transplantation has potent therapeutic effects and could be a potential therapy for clinically intractable epilepsies.