Kris Engelstad

Glucose transporter type I deficiency syndrome: Epilepsy phenotypes and outcomes

Purpose:  Glut 1 deficiency syndrome (DS) is defined by hypoglycorrhachia with normoglycemia, acquired microcephaly, episodic movements, and epilepsy refractory to standard antiepileptic drugs (AEDs). Gold standard treatment is the ketogenic diet (KD), which provides ketones to treat neuroglycopenia. Our purpose is (1) to describe epilepsy phenotypes in a large Glut 1 DS cohort, to facilitate diagnosis; and (2) to describe cases in which non‐KD agents achieved seizure freedom (SF), highlighting potential adjunctive treatments.

Role of reentry of in vivo alloMHC peptide-activated T cells into the adult thymus in acquired systemic tolerance.

BACKGROUND T cell recognition of alloMHC peptide presented by self dendritic cells via the indirect pathway of allorecognition in the thymus induces T cell tolerance. Most recently we have shown that the i.v. administration of immunodominant Wistar Furth MHC class I (RT1.Au) peptide 5- (P5) pulsed myeloid or lymphoid dendritic cells induces operational tolerance to a fully MHC-mismatched cardiac allograft. This finding led us to hypothesize that circulation of peripheral P5-activated T cells to the thymus plays an important role in the induction of acquired tolerance. METHODS We used the adoptive transfer of 111Indium-oxine- (111In-oxine) labeled P5-pulsed syngeneic dendritic cells and in vivo P5-activated syngeneic T cells to study the role of their circulation to the thymus in the induction of transplantation tolerance. RESULTS Intravenously administered 111In-oxine-labeled naïve DC actively migrated to and localized in the liver and spleen but did not enter the lymph nodes, bone marrow, and thymus. In vitro peptide-pulsed dendritic cells had a similar pattern of tissue localization except for a modest number of myeloid but not lymphoid DC entering the thymus. The demonstration that adoptive transfer of in vivo peptide-primed T cells induces permanent graft survival in antilymphocyte serum transiently immunosuppressed syngeneic secondary hosts led us to examine the traffic of in vivo activated T cells. Whereas naïve syngeneic T cells preferentially homed to the peripheral lymphoid organs, they did not reenter the thymus. In contrast, in vivo peptide-activated peripheral T cells migrated to and accumulated in the thymus, thus confirming that reentry of T cells to the thymus is restricted to in vivo activated T cells. Although antilymphocyte serum immunosuppression significantly reduced circulation of primed T cells to the thymus, it did not completely abolish it, as seen with gamma-irradiated primed T cells. CONCLUSION These findings provide the first formal evidence directly linking reentry of in vivo alloMHC peptide-activated T cells to the thymus with the induction and possibly maintenance of acquired antigen-specific tolerance. Our results suggest that the thymus is open to a two-way traffic with the periphery and may function as a repository of immunological memory.

Mechanisms of acquired thymic tolerance: induction of transplant tolerance by adoptive transfer of in vivo allomhc peptide activated syngeneic T cells.

Background. Our most recent observation that i.v. injection ofWistar-Furth (WF) major histocompatibility complex Class I peptide 5(P5)-pulsed self-myeloid or lymphoid dendritic cells (DC) inducestransplantation tolerance suggests that adoptive transfer of in vivoallopeptide-primed host T cells might induce acquired tolerance through theirinteraction with thymicDC. Methods. To examine this hypothesis, host myeloid DC cultured in ratgranulocyte/macrophage colony stimulating factor and interleukin 4 were pulsedin vitro with P5 and injected intravenously into syngeneic ACI rats. The Tcells primed to P5 via the indirect pathway of allorecognition were harvested7 days later and administered by either intravenously or intrathymically intosyngeneic ACI recipients of WF cardiacallografts. Results. Syngeneic T cells obtained from the spleen of P5-primedrats had a high mixed lymphocyte reaction proliferative response to P5presented by self-DC. I.v. administration of2×10 7 P5-primed alloreactive purified hostsplenic T cells alone on day −7 significantly(P <0.001) prolonged cardiacallograft survival from 10.5±1.0 days to 18.6±1.8 days in theWF-to-ACI rat combination. I.v. injection of P5-activated host T cellscombined with 0.5 ml antilymphocyte serum (ALS)-transient immunosuppression onday −7 led to 100% donor-specific permanent graft survival (>200days). Thymectomy before i.v. injection of P5-activated syngeneic T cells ledto acute graft rejection, suggesting that the homing of in vivo activated Tcells to the host thymus might play a role in the induction of tolerance. Tofurther define the role of the recipient thymus in this model, we examined theeffects of intrathymic (i.t.) injection of P5-primed alloreactive T cells ongraft survival and found that i.t. administration of the P5-primed T cells onday −7 alone significantly prolonged graft survival (15.0±0.7days) and when combined with 0.5 ml ALS led to donor-specific permanent graftsurvival. The long-term unresponsive recipients permanently (>100 days)accepted second-set donor-specific cardiac allografts but not third-party(Lewis)grafts. Conclusions. These findings demonstrate that the adoptive transfer ofsplenic T cells primed to an indirectly presented donor peptide inducestransplantation tolerance in a transiently immunosuppressed secondarysyngeneic recipient. Our data suggest that the interaction of thymic DC withactivated peripheral T cells induces alloantigen (Ag)-specific T-celltolerance by either inactivation or deletion of alloreactive T cells in thethymus. This observation provides the first formal evidence that theinteraction between thymic DC and activated peripheral T cells thatcontinuously circulate through the thymus plays an important role in theinduction and maintenance of Ag-specifictolerance.

Migration patterns of dendritic cells in the rat: Comparison of the effects of γ and UV-B irradiation on the migration of dendritic cells and lymphocytes☆

To further define the underlying mechanisms of immune suppression induced by UV-B irradiation, we have examined the kinetics of homing patterns of in vitro UV-B-irradiated and gamma-irradiated-thoracic duct lymphocytes (TDL) compared to dendritic cells (DC). Our findings show that 111In-oxine-labeled TDL specifically home to the spleen, liver, lymph nodes, and bone marrow with subsequent recirculation of a large number of cells from the spleen to lymph nodes. In contrast, DC preferentially migrate to the spleen and liver with a relatively insignificant distribution to lymph nodes and an absence of subsequent recirculation. Splenectomy prior to cell injection significantly diverts the spleen-seeking DC to the liver but not to the lymph nodes, while the homing of TDL to lymph nodes is significantly increased. In vitro exposure of 111In-oxine labeled TDL to gamma irradiation does not significantly impair immediate homing to lymphoid tissues but inhibits cell recirculation between 3 and 24 hr. In contrast, gamma irradiation does not affect the tissue distribution of labeled DC, suggesting that DC are more radioresistant to gamma irradiation than TDL. Unlike the findings in animals injected with gamma-irradiated cells, UV-B irradiation virtually abolished the homing of TDL to lymph nodes and significantly reduced the homing of the spleen-seeking DC to the splenic compartment while a large number of cells were sequestered in the liver. The results of in vitro cell binding assay show that TDL, unlike DC, have the capacity to bind to high endothelial venules (HEV) within lymph node frozen sections while gamma and UV-B irradiation significantly inhibit the binding of TDL to lymph node HEV. These findings suggest that: (i) DC, unlike TDL, are unable to recirculate from blood to lymph nodes through HEV; (ii) although gamma irradiation impairs TDL recirculation, it does not affect DC tissue distribution; and (iii) UV-B irradiation impairs both TDL and DC migration patterns. We conclude that the lack of capacity of irradiated TDL to home to lymph nodes is due to damage to cell surface homing receptors and that the failure of DC to home to the lymph node microenvironment is related to the absence of HEV homing receptors on their cell surface.

Induction of stable chimerism and transplantation tolerance to rat islet and heart allografts by ultraviolet-B modulation of bone marrow cells.

Ultraviolet-B irradiation (UV-B) (700 J/m2) of BM cells prior to transplantation into lethally gamma-irradiated (1050 rads) allogeneic rats prevents the development of GVHD and results in stable chimerism. This study was developed to determine if UV-B modulation of BMT is useful for preconditioning recipients for the induction of tolerance to donor islets and heart allografts. Lethally irradiated Lewis rats that received UV-B irradiated (700 J/m2) WF BMT (10(8) BM cells) demonstrated stable chimerism without any evidence of GVHD. The stable Lewis chimeras were made diabetic with streptozotocin (STZ) at 28-35 days after BMT and subdivided into 3 experimental groups that received 1000-1200 islets from WF, Lewis, or BN (third-party), respectively. The results showed that group I diabetic Lewis chimeras accepted permanently (greater than 300 days) BM donor WF islets and became normoglycemic. When 3 of 6 Lewis chimeras transplanted with WF islets were rechallenged with WF hearts 60 days after islet grafts, they accepted both islets and cardiac allografts permanently (greater than 240 days). Similarly, the remaining 3 animals accepted Lewis cardiac allografts permanently, thus indicating tolerance to both donor and recipient alloantigens. Group II diabetic chimeras accepted permanently (greater than 300 days) recipient (Lewis) islets. In contrast, group III chimeras rejected acutely (7-8 days) third-party (BN) islets. However, when these animals that rejected BN islets and again became diabetic were retransplanted with BM donor-type (WF) islets, they became permanently normoglycemic (greater than 200 days). This finding emphasizes the specificity of the induction of tolerance in this model and the apparent lack of organ-specific sensitization. To define the underlying mechanism of tolerance, in vivo adoptive transfer of 10(8) spleen cells to naive Lewis or WF recipients, obtained from tolerant Lewis chimeras carrying donor islets and heart allografts, showed no prolongation of cardiac allografts in the unmodified syngeneic hosts, thus questioning the role of suppressor mechanisms in the tolerant rats. Furthermore, cells from the tolerant chimeras that showed no mixed lymphocyte reaction (MLR) response to Lewis or; WF alloantigens failed to suppress anti-Lewis and anti-WF MLR-response in coculture MLR. These results suggest that tolerance to donor alloantigens in the UV-B BMT model is most likely due to selective elimination of anti-BM donor helper or effector cell precursors (clonal deletion) rather than induction of suppressor cell activity. This study demonstrates that this relatively simple and effective approach to modulation of T cells in BM treatment may be potentially useful in the induction of tolerance to donor organs.

Prevention of GVHD by modulation of rat bone marrow with UV-B irradiation: II. Kinetics of migration of UV-B-irradiated bone marrow cells in naive and lethally irradiated rats☆

UV-B irradiation (700 J/m2) of bone marrow (BM) cells prior to transplantation into lethally gamma-irradiated (1050 rad) allogeneic rats prevents the development of GVHD and results in a stable mixed lymphohematopoietic chimerism. To better understand the underlying mechanisms of the development of stable radiation chimeras in this model, this study was designed to examine whether the dose (700 J/m2) of UV-B irradiation used for the modulation of the BM inoculum would affect the homing pattern of radiolabeled BM cells compared to that of thoracic duct lymphocytes (TDL) in the naive and lethally irradiated recipients. The results showed that intravenously administered, 111Indium-oxine-labeled, unmodified TDL home specifically to the spleen, lymph nodes, and BM compartments with a subsequent recirculation of a large number of cells from the spleen to the lymph nodes. In contrast, radiolabeled, unmodified BM cells migrate specifically to the spleen, liver, and BM with the lymph nodes, thymus, and nonlymphoid organs containing very little amounts of radioactivity. The stable concentrations of radioactivity in the lymphoid and nonlymphoid compartments between 3 and 72 hr after injection suggest that BM cells, unlike TDL, do not recirculate. The migration pattern of BM cells in the naive recipient was not significantly different from that seen in lethally irradiated animals except for the higher concentration of radioactivity in the spleen and BM of irradiated animals compared to that seen in naive recipients. The similarity of tissue localization of BM cells in naive or in irradiated syngeneic recipients to that of allogeneic recipients suggests that the homing of BM cells is not MHC restricted. Our findings of similarity between tissue localization of UV-B-irradiated labeled BM cells and unmodified BM cells in naive and lethally irradiated recipients suggest that a dose of 700 J/m2 of UV-B irradiation is not capable of impairing BM cell migration although it is sufficient to abolish the homing of TDL to the HEV-bearing organs. Thus, our results show that BM cells are less susceptible to cell damage by UV-B irradiation than lymphocytes thereby providing the rationale for ex vivo modulation (rather than elimination) of mature T-lymphocytes in the donor BM inoculum with UV-B irradiation. This relatively simple and effective approach to modulation of T-cells in donor BM inoculum may be potentially useful in preventing GVHD without endangering successful engraftment in larger animals and in man.

Cellular immunity in allograft rejection: Role of lymphocyte subpopulations and T-cell subsets in rat cardiac allograft rejection☆

In this study, cellular requirements for rejection are examined by the use of adoptive transfer assays in the ACI to Lewis cardiac allograft model. The findings show that adoptive transfer of 1 x 10(8) spleen cells (SpL), 5 x 10(7) T-cells, and 2 x 10(7) helper T-cells (W3/25+) obtained from normal, nonsensitized donors restores acute ACI graft rejection in sublethally irradiated (750 rad) Lewis recipients. In contrast, reconstitution with 2 x 10(7) cytotoxic T-cells (0X8+) does not restore first-set graft rejection. Reconstitution of the irradiated recipients with either W3/25+ or 0X8+ T-cells obtained from specifically sensitized syngeneic donors resulted in acute rejection. The W3/25+ T-cell subset was significantly more potent (P less than 0.01) in effecting rejection on a per-cell basis. Adoptive transfer of SpL, T-cells, and 0X8+ T-cells obtained from sensitized rats led to accelerated cardiac allograft rejection in the naive secondary recipients while W3/25+ T-cells did not. This study suggests that although the W3/25+ T-cells alone have the capacity to initiate first-set graft rejection, both W3/25+ and 0X8+ subsets appear to be critical to the completion of rejection of heart allografts. We also examined the capacity of adoptively transferred B-cells from sensitized donors to influence graft rejection. Our findings suggest that while B-cells fail to restore the capacity for graft rejection in irradiated recipients, they can, however, present MHC antigens to the secondary naive host thus causing allosensitization which results in accelerated rejection of a subsequent graft.