The increasing recognition of the contribution of the immune system to activate and prime regeneration implies that tissue engineering strategies and biomaterials design should target regulation of early immunological processes. We previously proposed the cell-based engineering and devitalization of extracellular matrices (ECMs) as a strategy to generate implant materials delivering custom-defined signals. Here, in the context of bone regeneration, we aimed at enhancing the osteoinductivity of such ECMs by enriching their immunomodulatory factors repertoire. Priming with IL1β a cell line overexpressing BMP-2 enabled engineering of ECMs preserving osteoinductive signals and containing larger amounts of angiogenic (VEGF) and pro-inflammatory molecules (IL6, IL8 and MCP1). Upon implantation, these IL1β-induced materials enhanced processes typical of the inflammatory phase (e.g., vascular invasion, osteoclast recruitment and differentiation), leading to 'regenerative' events (e.g., M2 macrophage polarization) and ultimately resulting in faster and more efficient bone formation. These results bear relevance towards the manufacturing of potent off-the-shelf osteoinductive materials and outline the broader paradigm of engineering immunoinstructive implants to enhance tissue regeneration.
© 2022 The Authors.

The stimulator of interferon genes (STING) protein is an important and promising innate immune target for tumor therapy. However, the instability of the agonists of STING and their tendency to cause systemic immune activation is a hurdle. The STING activator, cyclic di-adenosine monophosphate (CDA), produced by the modified Escherichia coli Nissle 1917, shows high antitumor activity and effectively reduces the systemic effects of the "off-target" caused by the activation of the STING pathway. In this study, we used synthetic biological approaches to optimize the translation levels of the diadenylate cyclase that catalyzes CDA synthesis in vitro. We developed 2 engineered strains, CIBT4523 and CIBT4712, for producing high levels of CDA while keeping their concentrations within a range that did not compromise the growth. Although CIBT4712 exhibited stronger induction of the STING pathway corresponding to in vitro CDA levels, it had lower antitumor activity than CIBT4523 in an allograft tumor model, which might be related to the stability of the surviving bacteria in the tumor tissue. CIBT4523 exhibited complete tumor regression, prolonged survival of mice, and rejection of rechallenged tumors, thus, offering new possibilities for more effective tumor therapy. We showed that the appropriate production of CDA in engineered bacterial strains is essential for balancing antitumor efficacy and self-toxicity.

Systemic radiation treatments that preferentially irradiate cancer cells over normal tissue, known as targeted radionuclide therapy (TRT), have shown significant potential for treating metastatic prostate cancer. Preclinical studies have demonstrated the ability of external beam radiation therapy (EBRT) to sensitize tumors to T cell checkpoint blockade. Combining TRT approaches with immunotherapy may be more feasible than combining with EBRT to treat widely metastatic disease, however the effects of TRT on the prostate tumor microenvironment alone and in combinfation with checkpoint blockade have not yet been studied.
C57BL/6 mice-bearing TRAMP-C1 tumors and FVB/NJ mice-bearing Myc-CaP tumors were treated with a single intravenous administration of either low-dose or high-dose 90Y-NM600 TRT, and with or without anti-PD-1 therapy. Groups of mice were followed for tumor growth while others were used for tissue collection and immunophenotyping of the tumors via flow cytometry.
90Y-NM600 TRT was safe at doses that elicited a moderate antitumor response. TRT had multiple effects on the tumor microenvironment including increasing CD8 +T cell infiltration, increasing checkpoint molecule expression on CD8 +T cells, and increasing PD-L1 expression on myeloid cells. However, PD-1 blockade with TRT treatment did not improve antitumor efficacy. Tregs remained functional up to 1 week following TRT, but CD8 +T cells were not, and the suppressive function of Tregs increased when anti-PD-1 was present in in vitro studies. The combination of anti-PD-1 and TRT was only effective in vivo when Tregs were depleted.
Our data suggest that the combination of 90Y-NM600 TRT and PD-1 blockade therapy is ineffective in these prostate cancer models due to the activating effect of anti-PD-1 on Tregs. This finding underscores the importance of thorough understanding of the effects of TRT and immunotherapy combinations on the tumor immune microenvironment prior to clinical investigation.
© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.

The APOBEC family of cytidine deaminases is one of the most common endogenous sources of mutations in human cancer. Genomic studies of tumors have found that APOBEC mutational signatures are enriched in the HER2 subtype of breast cancer and are associated with immunotherapy response in diverse cancer types. However, the direct consequences of APOBEC mutagenesis on the tumor immune microenvironment have not been thoroughly investigated. To address this, we developed syngeneic murine mammary tumor models with inducible expression of APOBEC3B. We found that APOBEC activity induced antitumor adaptive immune responses and CD4+ T cell-mediated, antigen-specific tumor growth inhibition. Although polyclonal APOBEC tumors had a moderate growth defect, clonal APOBEC tumors were almost completely rejected, suggesting that APOBEC-mediated genetic heterogeneity limits antitumor adaptive immune responses. Consistent with the observed immune infiltration in APOBEC tumors, APOBEC activity sensitized HER2-driven breast tumors to anti-CTLA-4 checkpoint inhibition and led to a complete response to combination anti-CTLA-4 and anti-HER2 therapy. In human breast cancers, the relationship between APOBEC mutagenesis and immunogenicity varied by breast cancer subtype and the frequency of subclonal mutations. This work provides a mechanistic basis for the sensitivity of APOBEC tumors to checkpoint inhibitors and suggests a rationale for using APOBEC mutational signatures and clonality as biomarkers predicting immunotherapy response in HER2-positive (HER2+) breast cancers.
©2021 American Association for Cancer Research.

Vertical sleeve gastrectomy (VSG) is the most commonly performed bariatric/metabolic surgery, exhibiting a high rate of diabetes remission in humans. To elucidate the molecular mechanisms of VSG, we performed transcriptomic analysis of the liver, fat, and muscle in VSG mice. C57BL/6 mice fed a high-fat diet were randomly assigned to sham or VSG surgery. The sham-operated mice were fed ad libitum (sham group) or pair-fed (sham-PF group) matching their food intake to the VSG-operated mice. Comparative transcriptomic analysis of the liver, fat, and muscle using RNA sequencing was performed. VSG reduced body weight and improved glucose tolerance compared to the sham group, but not more than the sham-PF group. Improvement in fatty liver and adipose tissue inflammation was comparable between VSG and sham-PF. However, global gene expression profiles showed distinctive changes in the liver, fat, and muscle of the VSG group compared to both the sham or sham-PF groups. The liver showed the most prominent gene expression changes. Immune response-related pathways were commonly upregulated in the three organs of the VSG group compared to the sham or sham-PF. VSG induces organ-specific gene expression changes in the liver, fat, and muscle, which may play critical roles in metabolic improvements after VSG.