Risk factors of Omicron variant associated acute encephalitis/encephalopathy in children.

BACKGROUND: Outbreak of Omicron BA.2 in Taiwan led to an increased number of acute encephalitis/encephalopathy cases in children and several fatal cases drew public attention. In pre-Omicron period, pediatric cases of COVID-19-associated acute encephalitis have been reported and during Omicron epidemic, febrile convulsions, encephalitis were mentioned more frequently. The outcome of patients with neurological complications was worse. However, few studies investigated the risk factors, pathophysiology and prognosis of COVID-19-associated encephalitis/encephalopathy. Here, we describe the presentation of pediatric cases of COVID-19-associated acute encephalitis/encephalopathy and explore the associated risk factors. METHODS: Pediatric patients with confirmed SARS-CoV-2 infections were prospectively enrolled at admission at Chang Gung Memorial Hospital between April and August 2022. Patients were categorized into groups of acute encephalitis/encephalopathy, febrile convulsions or mild disease. Demographic descriptions, clinical manifestations and laboratory data were collected. RESULTS: Of 288 acute COVID-19 patients, there were 38 (13.2%) acute encephalitis/encephalopathy, 40 (13.9%) febrile convulsions, and 210 (72.9%) mild disease. Among acute encephalitis/encephalopathy group, the mean age was 68.3 ± 45.0 months. The common neurological symptoms were lethargy (65.8%), seizures (52.6%), and impaired consciousness (34.2%). Over 3 years old (adjusted odds ratio [aOR]: 7.57, p < 0.001), absolute neutrophil count ≥3150/µL (aOR: 5.46, p = 0.008), and procalcitonin ≥0.5 ng/mL (aOR: 4.32, p = 0.021) were independent factors for acute encephalitis/encephalopathy. CONCLUSIONS: Most cases of COVID-19-associated acute encephalitis/encephalopathy showed no evidence of direct viral invasion but associations with older age, increased peripheral neutrophil, and serum procalcitonin. These findings may imply the neutrophil-mediated systemic inflammatory response plays an important role on central nerve system, leading to cerebral dysfunction.

Modulation of immune response and T-cell regulation by donor adipose-derived stem cells in a rodent hind-limb allotransplant model.

BACKGROUND: In this study, the authors investigated whether donor adipose-derived stem cells have immunomodulatory effects, such as regulation of T cells, modulation of related cytokines, and prolongation of composite tissue allotransplantation survival, in a rodent hind-limb model. METHODS: Adipose-derived stem cells were obtained from donor adipose tissue and co-cultured with CD3 T cells from allogenic splenocytes for in vitro studies. Orthotopic hind-limb allotransplants were performed from Brown Norway to Lewis rats (day 0). Group 1 (control group) did not receive any treatment. Group 2 received cyclosporin A on days 0 to 20. Group 3 received antilymphocyte serum (day -4 and day 1) and cyclosporin A (days 0 to 20). Group 4 received cyclosporin A (days 0 to 20), antilymphocyte serum (day -4 and day 1), and adipose-derived stem cells (2 × 10 cells/time administered intravenously on days 7, 14, and 21). RESULTS: Adipose-derived stem cells exert immunomodulatory effects including suppressing T-cell proliferation and increasing CD4/CD25/Foxp3 regulatory T cells in vitro. The in vivo study revealed that, compared with untreated control, rats administered adipose-derived stem cells along with transient antilymphocyte serum and cyclosporin A treatment had significantly prolonged allotransplant survival (p < 0.001), decreased allotissue rejection, significantly elevated donor cell chimerism, and increased CD4/CD25/Foxp3 regulatory T cells in peripheral blood and alloskin tissue with up-regulation of transforming growth factor-ß and interleukin-10 levels. CONCLUSIONS: In combination with transient immunosuppression, adipose-derived stem cells modulate the immune system and significantly prolong allotransplant survival. The underlying mechanisms include changes in antiinflammatory cytokine expression and T-cell functions.

Prolongation of composite tissue allotransplant survival by treatment with bone marrow mesenchymal stem cells is correlated with T-cell regulation in a swine hind-limb model.

BACKGROUND: Recently published reports indicate that treatment with mesenchymal stem cells combined with bone marrow transplantation could prolong survival after composite tissue allotransplantation. This study investigated whether bone marrow mesenchymal stem cells combined with irradiation and short-term immunosuppressant therapy, but without bone marrow transplantation, could prolong composite tissue allotransplantation survival. Correlation with regulatory T-cell populations was also evaluated in a swine hind-limb model. METHODS: Heterotopic hind-limb transplantation was performed in outbred miniature swine. Group I (n = 4) was the untreated control. Group II (n = 3) received mesenchymal stem cells alone (on days -1, 3, 7, 14, and 21). Group III (n = 5) received cyclosporine A (on days 0 through 28). Group IV (n = 3) received irradiation (on day -1), mesenchymal stem cells (on days 1, 7, 14, and 21), and cyclosporine A (on days 0 to 28). Swine viability and signs of allograft rejection were monitored postoperatively. Histopathologic changes in allografts were examined. The expression and localization of CD4+/CD25+ and CD4+/FoxP3+ T cells were assessed using flow cytometry and immunohistochemistry. RESULTS: Treatment with mesenchymal stem cells along with irradiation and cyclosporine A resulted in significant increases in allograft survival as compared with other groups (>120 days; p = 0.018). Histologic examination revealed the lowest degree of rejection in grafted skin and interstitial muscle layers in the mesenchymal stem cell/irradiation/cyclosporine A group. Flow cytometric analysis revealed a significant increase in the percentage of CD4+/CD25+ and CD4+/FoxP3+ T cells in both the blood and graft in the mesenchymal stem cell/irradiation/cyclosporine A group. CONCLUSION: These results suggest that prolonged survival after composite tissue allotransplantation induced by treatment with mesenchymal stem cells combined with irradiation/cyclosporine A is correlated with regulatory T cells.

Alloantigen-pulsed host dendritic cells induce T-cell regulation and prolong allograft survival in a rat model of hindlimb allotransplantation.

BACKGROUND: Composite tissue allotransplantation is restricted due to the risks presented by long-term therapeutic immunosuppression. This study is conducted to investigate whether treatment with recipient immature dendritic cells (DCs) pulsed with donor alloantigens can prolong allograft survival and induce T-cell regulation in a rodent model. MATERIALS AND METHODS: Orthotopic hindlimb transplants from Brown-Norway (RT1(n)) to Lewis (RT1(1)) rats were performed (day 0). DCs were propagated from the recipient bone marrow and pulsed with the donor alloantigen lysate. Group 1 (control group) did not receive any treatment. Groups 2 and 3 received cyclosporine A (CsA) at a concentration of 10 and 16 mg.kg(-1).day(-1), respectively, on days 0-20 following composite tissue allotransplantation. Group 4 received antilymphocyte serum (i.p. administered 4 d before and 1 d after transplantation) therapy. Group 5 received combined treatment with CsA (10 mg.kg(-1).day(-1), days 0-20) and donor alloantigen-pulsed recipient DCs (i.v. administered on days 7, 14, and 21). Group 6 received combined treatment with CsA (10 mg.kg(-1).day(-1) on days 0-20), antilymphocyte serum (administered i.p. 4 d before and 1 d after transplantation), and DCs (administered i.v. on days 7, 14, and 21). Graft rejection was defined as epidermolysis/desquamation of the donor skin. The mixed lymphocyte reaction was performed to determine the donor T-cell reactivity. Tissue samples were biopsied to analyze the histological changes, and flow cytometry was performed to quantify the donor T-cells. RESULTS: Allograft survival was significantly prolonged (>200 d) in Group 6 when compared with the other groups (P < 0.001). The mixed lymphocyte reaction performed for Group 6 revealed hyporesponsiveness of the T-cells to donor alloantigens. Flow cytometric analysis in Group 6 revealed a significant increase in the percentage of CD4(+)/CD25(+) and CD4(+)/foxP3(+) T-cells expression, and significant increase in the percentage of donor cells (RT1(n)) in the recipient peripheral blood. Immunohistochemical staining of allo-skin revealed a significant increase in the proportion of CD25(+) cells in the subcutaneous and dermis layers in Group 6, as compared to other groups. CONCLUSION: Treatment with donor alloantigen-pulsed recipient immature DCs in combination with transient immunosuppression prolongs allograft survival and induced tolerance by inducing T-cell hyporesponsiveness to donor alloantigens and increasing the CD4(+)/CD25(+) T-cell population.