Little is known about the mechanisms involved in the dysfunction of melanocytes in vitiligo epidermis. It is hypothesized that some cytokine/receptor interactions may be affected, resulting in dysfunction and/or loss of melanocytes. This study has compared the expression of endothelin (ET)-1, the ET-1 receptor (ET(B)R), granulocyte macrophage colony stimulating factor (GM-CSF), stem cell factor (SCF), the SCF receptor (KIT protein), tyrosinase, and S100 alpha between lesional and non-lesional vitiligo epidermis. Analysis by reverse transcription-polymerase chain reaction (RT-PCR) and by western blotting for ET-1 and SCF unexpectedly demonstrated up-regulated expression of these cytokines in lesional vitiligo epidermis. Immunohistochemistry with antibodies to melanocyte markers revealed that at the edge of the lesional epidermis, melanocytes remain and express tyrosinase, S100 alpha and ET(B)R, but not KIT protein or melanocyte-specific microphthalmia-associated transcription factor (MITF-M). Quantitation of the staining revealed a slight or moderate decrease in the number of S100 alpha, tyrosinase, and ET(B)R-positive cells at the edge of the lesional epidermis. In contrast, the number of cells expressing KIT protein was markedly decreased at the edge of the lesional epidermis compared with the non-lesional epidermis. At the centre of the lesional epidermis, there was complete loss of melanocytes expressing KIT protein, S100 alpha, ET(B)R, and/or tyrosinase. Western blotting revealed down-regulated expression of c-kit and MITF-M proteins at the edge of the lesional epidermis in vitiligo. These findings suggest that reduction in the expression of KIT protein by melanocytes and its downstream effectors, including MITF-M, may be associated with the dysfunction and/or loss of melanocytes in vitiligo epidermis.

IntroductionSmall animal models allowing for systematic in vivo studies to address important questions relevant to human immunology have been long awaited. 1 In the past 20 years, much effort has been put into developing better protocols to establish a functional human immune system in immunodeficient mice, and the main methodologic approaches include transplantation of human fetal tissues (thymus and liver) or hematopoietic stem/progenitor cells. [2][3][4][5][6] Although human thymopoiesis and human T-cell development can be achieved by transplantation of human CD34 ϩ cord blood cells into BALB/c RAG2 null ␥c null or nonobese diabetic severe combined immunodeficiency (NOD/SCID)/␥c null newborn mice, 5,6 transplantation of hematopoietic stem/progenitor cells has been inefficient in achieving human T-cell development in adult mice. In a recent study, human T-cell development was detected in adult NOD/SCID/IL2R␥ null mice receiving human CD34 ϩ cord blood cells. 7 However, the levels of human T cells in these mice were low, with approximately 3% and 5% of human CD3 ϩ T cells in the blood and spleen, respectively, 4 months after transplantation. Furthermore, although a small portion of the grafted mice showed production of antigen-specific antibodies after HIV infection, the failure to produce anti-HIV human IgG in these mice suggests a lack of efficient class switching in this humanized mouse (hu-mouse) model.Considering the essential role of the thymus in determining the major histocompatibility complex (MHC) restriction of human T cells and in the development of regulatory T cells, 8 we have established a hu-mouse model in which human T cells are generated in an autologous human thymus. Although transplantation of fetal human thymus (Thy) and liver (Liv) tissues alone can lead to human thymopoiesis and T-cell development in NOD/SCID mice, our previous studies showed that combined transplantation of human fetal Thy/Liv and intravenous administration of CD34 ϩ cells is required to establish a functional human immune system capable of mediating in vivo immune responses. 9 NOD/SCID mice receiving combined human Thy/ Liv and CD34 ϩ fetal liver cell (FLC) transplants, but not those receiving human Thy/Liv alone, showed long-term repopulation with multilineage human lymphohematopoietic cells, including T cells, B cells, and antigen-presenting cells (APCs); the formation of secondary lymphoid organs with normal structural features; and the production of high levels of human IgM and IgG. Consistent with our findings, Melkus et al subsequently reported that NOD/SCID mice reconstituted with human fetal Thy/Liv plus CD34 ϩ cells mediate strong cellular immune responses against Epstein-Barr virus (EBV) and toxic shock syndrome toxin-1 (TSST-1). 10 However, the ability of human fetal Thy/Liv/CD34 ϩ cell-grafted hu-mice to mediate T celldependent antibody responses has not been well established. MethodsHu-mouse preparation and human chimerism analysis was performed as previously described. 9 Hu-mice were immunized 14 weeks ...

Bryostatin 1 is an exceedingly scarce marine-derived natural product that is in clinical development directed at HIV/AIDS eradication, cancer immunotherapy, and the treatment of Alzheimer’s disease. Despite this unique portfolio of indications, its availability has been limited and variable, thus impeding research and clinical studies. Here, we report a total synthesis of bryostatin 1 that proceeds in 29 total steps (19 in the longest linear sequence, >80% average yield per step), collectively produces grams of material, and can be scaled to meet clinical needs (~20 grams per year). This practical solution to the bryostatin supply problem also opens broad, facile, and efficient access to derivatives and potentially superior analogs.

The ability of HIV to establish a long-lived latent infection within resting CD4+ T cells leads to persistence and episodic resupply of the virus in patients treated with antiretroviral therapy (ART), thereby preventing eradication of the disease. Protein kinase C (PKC) modulators such as bryostatin 1 can activate these latently infected cells, potentially leading to their elimination by virus-mediated cytopathic effects, the host’s immune response and/or therapeutic strategies targeting cells actively expressing virus. While research in this area has focused heavily on naturally-occurring PKC modulators, their study has been hampered by their limited and variable availability, and equally significantly by sub-optimal activity and in vivo tolerability. Here we show that a designed, synthetically-accessible analog of bryostatin 1 is better-tolerated in vivo when compared with the naturally-occurring product and potently induces HIV expression from latency in humanized BLT mice, a proven and important model for studying HIV persistence and pathogenesis in vivo. Importantly, this induction of virus expression causes some of the newly HIV-expressing cells to die. Thus, designed, synthetically-accessible, tunable, and efficacious bryostatin analogs can mediate both a “kick” and “kill” response in latently-infected cells and exhibit improved tolerability, therefore showing unique promise as clinical adjuvants for HIV eradication.