Restoration of functional sperm production in irradiated pubertal rhesus monkeys by spermatogonial stem cell transplantation.

BACKGROUND: In male pre-pubertal cancer patients, radiation and chemotherapy impact future fertility by eradication of spermatogonial stem cells (SSCs). In macaques, spermatogenesis could be regenerated by intratesticular transplantation of SSCs, but only a small percentage of spermatozoa produced were of donor origin. Transient hormone suppression with a GnRH antagonist (GnRH-ant) enhanced spermatogenic recovery from transplanted SSCs. OBJECTIVES: To evaluate donor-derived and endogenous spermatogenic recovery after SSC transplantation into irradiated monkeys and to test whether hormone suppression around the time of transplantation facilitates spermatogenic recovery. MATERIALS AND METHODS: Testes of 15 adult rhesus monkeys were irradiated with 7 Gy and 4 months later transplanted, to one of the testes, with cryopreserved testicular cells containing SSCs from unrelated monkeys. Monkeys were either treated with GnRH-ant for 8 weeks before transplantation, GnRH-ant from 4 weeks before to 4 weeks after transplantation, or with no GnRH-ant. Tissues were harvested 10 months after transplantation. RESULTS: Two of the 15 monkeys, a control and a pre-transplantation GnRH-ant-treated, showed substantially higher levels of testicular spermatogenesis and epididymal sperm output in the transplanted side as compared to the untransplanted. Over 84% of epididymal spermatozoa on the transplanted side had the donor genotype and were capable of fertilizing eggs after intracytoplasmic sperm injection forming morulae of the donor paternal origin. Low levels of donor spermatozoa (~1%) were also identified in the epididymis of three additional monkeys. Transplantation also appeared to enhance endogenous spermatogenesis. DISCUSSION AND CONCLUSION: We confirmed that SSC transplantation can be used for restoration of fertility in male cancer survivors exposed to irradiation as a therapeutic agent. The success rate of this procedure, however, is low. The success of filling the tubules with the cell suspension, but not the GnRH-ant treatment, was related to the level of colonization by transplanted cells.

Lymphocytes upregulate CD36 in adipose tissue and liver.

CD36 is a multifunctional scavenger receptor and lipid transporter implicated in metabolic and inflammatory pathologies, as well as cancer progression. CD36 is known to be expressed by adipocytes and monocytes/macrophages, but its expression by T cells is not clearly established. We found that CD4 and CD8 T cells in adipose tissue and liver of humans, monkeys, and mice upregulated CD36 expression (ranging from ~5-40% CD36+), whereas little to no CD36 was expressed by T cells in blood, spleen, and lymph nodes. CD36 was expressed predominantly by resting CD38-, HLA.DR-, and PD-1- adipose tissue T cells in monkeys, and increased during high-fat feeding in mice. Adipose tissue and liver promote a distinct phenotype in resident T cells characterized by CD36 upregulation.

Synthesis of cananodine by intramolecular epoxide opening.

Cananodine is a guaipyridine alkaloid with activity against liver cancer. Cananodine was synthesized using a remarkable intramolecular opening of a trisubstituted epoxide as the key step in construction of the seven-membered carbocycle of the target. The epoxide opening strategy allows all four stereoisomers of cananodine to be prepared.

Less Is More: Low-dose Prothrombin Complex Concentrate Effective in Acute Care Surgery Patients.

Optimal dosing of prothrombin complex concentrate (PCC) has yet to be defined and varies widely due to concerns of efficacy and thrombosis. We hypothesized a dose of 15 IU/kg actual body weight of a three-factor PCC would effectively correct coagulopathy in acute care surgery patients. Retrospective review of 41 acute care surgery patients who received 15 IU/kg (± 10%) actual body weight PCC for correction of coagulopathy. Demographics, laboratory results, PCC dose, blood and plasma transfusions, and thrombotic complications were analyzed. We performed subset analyses of trauma patients and those taking warfarin. Mean age was 69 years (18-94 years). Thirty (73%) trauma patients, 8 (20%) emergency surgery patients, 2 (5%) burns, and 1 (2%) nontrauma neurosurgical patient were included. Mean PCC dose was 1305.4 IU (14.2 IU/kg actual body weight). Mean change in INR was 2.52 to 1.42 (p 0.00004). Successful correction (INR <1.5) was seen in 78 per cent. Treatment failures had a higher initial INR (4.3 vs 2.03, p 0.01). Mean plasma transfusion was 1.46 units. Mean blood transfusion was 1.61 units. Patients taking prehospital warfarin (n = 29, 71%) had higher initial INR (2.78 vs 1.92, p 0.05) and received more units of plasma (1.93 vs 0.33, p 0.01) than those not taking warfarin. No statistical differences were seen between trauma and nontrauma patients. One thrombotic event occurred. Administration of low-dose PCC, 15 IU/kg actual body weight, effectively corrects coagulopathy in acute care surgery patients regardless of warfarin use, diagnosis or plasma transfusion.

Inflammation programs self-reactive CD8+ T cells to acquire T-box-mediated effector function but does not prevent deletional tolerance.

CD8(+) T cells must detect foreign antigens and differentiate into effector cells to eliminate infections. But, when self-antigen is recognized instead, mechanisms of peripheral tolerance prevent acquisition of effector function to avoid autoimmunity. These distinct responses are influenced by inflammatory and regulatory clues from the tissue environment, but the mechanism(s) by which naive T cells interpret these signals to generate the appropriate immune response are unclear. The identification of the molecules operative in these cell-fate decisions is crucial for developing new treatment options for patients with cancer or autoimmunity, where manipulation of T cell activity is desired to alter the course of disease. With the use of an in vivo murine model to examine CD8(+) T cell responses to healthy self-tissue, we correlated self-tolerance with a failure to induce the T-box transcription factors T-bet and Eomes. However, inflammation associated with acute microbial infection induced T-bet and Eomes expression and promoted effector differentiation of self-reactive T cells under conditions that normally favor tolerance. In the context of a Listeria infection, these functional responses relied on elevated T-bet expression, independent of Eomes. Alternatively, infection with LCMV induced higher Eomes expression, which was sufficient in the absence of T-bet to promote effector cytokine production. Our results place T-box transcription factors at a molecular crossroads between CD8(+) T cell anergy and effector function upon recognition of peripheral self-antigen, and suggest that inflammation during T cell priming directs these distinct cellular responses.

CD8+ T cell exhaustion during persistent viral infection is regulated independently of the virus-specific T cell receptor.

During chronic viral infections, responses by virus-specific CD8(+) T cells become marginalized by the acquisition of functional defects and reduced cell numbers in a process defined as T cell exhaustion. Similarly, T cell tolerance to self-antigen is also characterized by impaired effector function and eventual deletion of self-reactive T cells. Induction of both tolerance and exhaustion involve many shared inhibitory mechanisms, thus similar therapeutic approaches have proven effective in these distinct environments. We previously demonstrated that tolerant self-reactive CD8(+) T cells expressing dual-T cell receptors (i.e., dual-TCR) could be rescued by immunization through a second TCR specific for a foreign antigen. These data revealed that T cell tolerance was regulated at the level of the self-reactive TCR. Here, dual-TCR CD8(+) T cells were used to examine if exhaustion during persistent viral infection could be rescued by an analogous strategy of immunization through a second TCR not involved in recognition of virus. In direct contrast to the rescue achievable in tolerant CD8(+) T cells, exhausted T cells were equally impaired through both TCR. These findings suggest that exhaustion is maintained by defects downstream of the virus-specific TCR, and establish that exhaustion and tolerance are distinctly regulated states of T cell dysfunction.

Durable adoptive immunotherapy for leukemia produced by manipulation of multiple regulatory pathways of CD8+ T-cell tolerance.

Tolerizing mechanisms within the host and tumor microenvironment inhibit T-cell effector functions that can control cancer. These mechanisms blunt adoptive immunotherapy with infused T-cells due to a complex array of signals that determine T-cell tolerance, survival, or deletion. Ligation of the negative regulatory receptors CTLA4, PD-1(PDCD1), or LAG3 on T-cells normally hinders their response to antigen through nonredundant biochemical processes that interfere with stimulatory pathways. In this study, we used an established mouse model of T-cell tolerance to define the roles of these inhibitory receptors in regulating CD8(+) T-cell tolerance during adoptive immunotherapy to treat leukemia. Blocking CTLA4 and PD-1 in vivo combined to promote survival of transferred T-cells despite powerful deletional signals that mediate Bim (BCL2L11)-dependent apoptosis. However, this dual blockade was not optimal for stimulating effector function by responding T-cells, which required the additional blockade of LAG3 to induce full expansion and allow the acquisition of robust cytolytic activity. Thus, the cooperation of multiple distinct regulatory pathways was needed for the survival and effector differentiation of adoptively transferred tumor-reactive CD8(+) T-cells. Our work defines the immune escape pathways in which simultaneous blockade could yield durable immunotherapeutic responses that can eradicate disseminated leukemia.