Lamb survival, glutathione redox state and immune function of neonates and lambs from periparturient Merino ewes supplemented with rumen-protected methionine.

Wool growth in Merino sheep demands a high level of sulphur amino acids, competing with body growth and the immune system, which may play a role in increasing the risk of lamb mortality. The hypothesis that dietary supplementation of methionine (Met) to Merino ewes during the late stages of pregnancy will improve foetal growth and alter immune competency of ewes and lambs was tested in a total of 120 grazing, pregnant Merino ewes. Sixty ewes were group-supplemented with 6.3 g/d rumen-protected Met (Met-Plus) per sheep from day 111 of pregnancy until day 7 after lambing, and the other 60 animals were used as a non-supplemented Control. Lambs from Met-supplemented ewes tended to be 10% heavier than Control lambs (p = 0.10), which did not affected the survival rate at weaning significantly. The supplemented ewes had slightly higher concentrations of total glutathione (GSH) in plasma at lambing (p < 0.06), but there were no differences between 1 and 3 months post-lambing in GSH, glutathione disulphide (GSSG) and the GSSG:GSH ratio. The GSSG:GSH ratio in the blood of ewes was elevated at lambing (p < 0.05), hinting that ewes were undergoing increased oxidative stress. The Met supplementation elevated the total IgG concentration (p < 0.05) in lambs aged 4 and 6 weeks, but did not change the IgG concentrations in colostrum and in plasma of 1-week-old lambs, and white blood cell counts and leukocyte types. The trend towards higher lamb birth weights in the Met-supplemented group requires further investigation as this may influence survival at birth and weaning.

The efficacy of tumor debulking surgery is improved by adjuvant immunotherapy using imiquimod and anti-CD40.

BACKGROUND: Tumor debulking surgery followed by adjuvant chemotherapy or radiotherapy is a standard treatment for many solid malignancies. Although this approach can be effective, it often has limited success against recurrent or metastatic cancers and new multimodality approaches are needed. Adjuvant immunotherapy is another potentially effective approach. We therefore tested the efficacy of the TLR7 agonist imiquimod (IMQ) combined with agonistic anti-CD40 in an incomplete debulking model of malignant mesothelioma. METHODS: Established subcutaneous murine ABA-HA mesothelioma tumors in BALB/c mice were surgically debulked by 75% and treated with either: i) saline; ii) intratumoral IMQ; iii) systemic anti-CD40 antibody, or using a combination of IMQ and anti-CD40. Tumour growth and survival were monitored, and the role of anti-tumor CD4 and CD8 T cells in therapeutic responses was determined. RESULTS: The combination therapy of partial debulking surgery, IMQ and anti-CD40 significantly delayed tumor growth in a CD8 T cell dependent manner, and promoted tumor regression in 25% of animals with establishment of immunological memory. This response was associated with an increase in ICOS+ CD8 T cells and tumor-specific CTL activity in tumor draining lymph nodes along with an increase in ICOS+ CD8 T cells in responding tumours. CONCLUSIONS: We show that the post-surgical environment can be significantly altered by the co-administration of adjuvant IMQ and anti-CD40, resulting in strong, systemic anti-tumor activity. Both adjuvants are available for clinical use/trial, hence this treatment regimen has clear translational potential.

Locally administered TLR7 agonists drive systemic antitumor immune responses that are enhanced by anti-CD40 immunotherapy.

Topical application of tumors with the TLR7 agonist imiquimod is an effective adjunct treatment for a range of primary dermatological cancers. However, for therapy to be effective against a broad range of solid tumor types, it must promote a strong systemic antitumor response that targets metastases in addition to primary tumor. We therefore investigated the potential of locally delivered imiquimod to stimulate an effective systemic antitumor response in a murine model of malignant mesothelioma (AB1-HA) with primary and distal tumors (dual tumor). Persistent delivery of imiquimod into primary tumor significantly retarded tumor growth in all treated mice compared with vehicle control. This local antitumor immune response required both CD8 T cells and NK cells, but not CD4 T cells, and was reliant on type I IFN induction. In vivo CTL studies and Ly6A/E staining of lymphocytes suggested that local imiquimod treatment had indeed induced a systemic, Ag-specific CD8 response. However, notably this response was not sufficient to retard the growth of an untreated distal tumor. Because local imiquimod treatment did not induce significant CD4 T cell responses, we investigated the efficacy of combining imiquimod with agonistic CD40 Ab (as a surrogate for CD4 T cell help). Combination of locally delivered imiquimod with systemic anti-CD40 immunotherapy not only significantly enhanced the local antitumor response, with 30% complete resolution, but it was also effective at significantly retarding growth of distal tumor. These results demonstrate that antitumor responses induced by locally delivered TLR7 agonists can be harnessed systemically for treating distal tumor.

Inhibitors selective for HDAC6 in enzymes and cells.

Histone deacetylase inhibitors with anticancer or anti-inflammatory activity bind to Class I or Class I and II HDAC enzymes. Here we compare selectivity of inhibitors of a Class II HDAC enzyme (HDAC6) and find one that retains high selectivity in macrophages.

Partial, but not complete, tumor-debulking surgery promotes protective antitumor memory when combined with chemotherapy and adjuvant immunotherapy.

Resection alone is rarely curative for advanced tumors, but the outcome generally improves with adjuvant therapy. We have previously shown that a combination of traditional chemotherapy (gemcitabine) and immunotherapy (anti-CD40/FGK-45) without surgery is synergistic and can lead to long-term cure when applied to small tumors. Such cured animals have immunologic memory and are protected from rechallenge. Here we investigate the effectiveness of combination chemotherapy and immunotherapy after partial or complete surgical debulking of large tumors. We found that complete resection followed by combination chemotherapy/immunotherapy led to a high rate of cure (>80%) but failed to induce a long-term, tumor-specific memory. Partial debulking followed by combination therapy elicited the same proportion of cured animals but in contrast to complete resection, a memory response was invoked. We postulate that chemotherapy induced apoptosis of the residual tumor cells following incomplete resection is absolutely required for the induction of long-term immunologic memory.

Targeting the effector site with IFN-alphabeta-inducing TLR ligands reactivates tumor-resident CD8 T cell responses to eradicate established solid tumors.

Effective antitumor CD8 T cell responses may be activated by directly targeting the innate immune system within tumors. We investigated this response by injecting a range of TLR agonists into established tumors using a mouse model of malignant mesothelioma stably transduced with the hemagglutinin (HA) gene as a marker Ag (AB1-HA). Persistent delivery of the dsRNA mimetic poly(I:C) into established AB1-HA tumors resulted in complete tumor resolution in 40% of mice, with the remaining mice also showing a significant delay in tumor progression. Experiments in athymic nude mice along with CD8 depletion and IFN-alphabeta blocking studies revealed that tumor resolution required both CD8 T cells and type I IFN induction, and was associated with local changes in MHC class I expression. Surprisingly, however, tumor resolution was not associated with systemic dissemination or tumor infiltration of effector CD8 T cells. Instead, the antitumor response was critically dependent on the reactivation of tumor-resident CD8 T cell responses. These studies suggest that, once reactivated, pre-existing local CD8 T cell responses are sufficient to resolve established tumors and that in situ type I IFN is a determining factor.