Biology subjects

Mohammadi, A. M.

Publications and source records attributed to Mohammadi, A. M..

3 recordsLinked to original sources

bioRxiv2021

Distinct cell adhesion signature defines glioblastoma myeloid-derived suppressor cell subsets

Increased myeloid-derived suppressor cell (MDSC) frequency is associated with worse outcomes and poor therapeutic response in glioblastoma (GBM). Monocytic (m) MDSCs represent the predominant subset in the GBM microenvironment. However, the molecular basis of mMDSC enrichment in the tumor microenvironment compared to granulocytic (g) MDSCs has yet to be determined. Here, we report that mMDSCs and gMDSCs display differences in their tumoraccelerating ability, with mMDSCs driving tumor growth in GBM models. Epigenetic assessments indicate enhanced gene accessibility for cell adhesion programs in mMDSCs and higher cellsurface integrin expression in mouse and human mMDSCs. Integrin {beta}1 blockage abrogated the tumor-promoting phenotype of mMDSCs and altered the immune profile in the tumor microenvironment. These findings suggest that integrin {beta}1 expression underlies the enrichment of mMDSCs in tumors and represents a putative immunotherapy target to attenuate myeloid cell-driven immune suppression in GBM. SummaryMyeloid-derived suppressor cells (MDSCs) drive glioblastoma growth; however, the function of specific MDSCs subsets is unclear. Bayik et al. demonstrate that adhesion programs are enhanced in monocytic MDSCs and responsible for their GBM-promoting function.

immunology↗

bioRxiv2020

Preclinical modeling of surgery and steroid therapy for glioblastoma reveals changes in immunophenotype that are associated with tumor growth and outcome

Recent advances in cancer immunotherapy have created a greater appreciation of potential anti-tumoral impacts by the immune system; however, individual patient responses have been variable. While immunotherapy is often given after standard-of-care treatment, the effects of initial interventions on the ability of the immune system to mount a response are not well understood and this may contribute to the variable response. For glioblastoma (GBM), initial disease management includes surgical resection, perioperative high-dose steroid therapy, chemotherapy, and radiation treatment. While new discoveries regarding the impact of chemotherapy and radiation on immune response have been made and translated to clinical trial design, the impact of surgical resection and steroids on the anti-tumor immune response has yet to be determined. Further, it is now accepted that steroid usage needs to be closely evaluated in the context of GBM and immunotherapy trials. To better model the clinical scenario in GBM, we developed a mouse model that integrates tumor resection and steroid treatment to understand how these therapies affect local and systemic immune responses. Using this model, we observed a systemic reduction in lymphocytes associated with surgical resection and identified a correlation between increased tumor volume and decreased circulating lymphocytes, a relationship that was obviated by dexamethasone treatment. Furthermore, we investigated the possibility of there being similar relationships in a cohort of patients with GBM and found that prior to steroid treatment, circulating lymphocytes inversely correlated with tumor volume. Lastly, correlating GBM patient data and outcomes demonstrated that peripherally circulating lymphocyte content varies with progression-free and overall survival, independent of tumor volume, steroid use, or tumor molecular profiles. These results highlight the systemic immunosuppressive effects that initial therapies can have on patients. Such effects should be considered when designing current and future immunotherapy clinical trials and underscore the importance of circulating lymphocytes as a possible correlate of GBM disease progression.

cancer biology↗

bioRxiv2019

Glioblastoma myeloid-derived suppressor cell subsets express differential macrophage migration inhibitory factor receptor profiles that can be targeted to reduce immune suppression

The application of tumor immunotherapy to glioblastoma (GBM) is limited by an unprecedented degree of immune suppression due to factors that include high numbers of immune suppressive myeloid cells, the blood brain barrier, and T cell sequestration to the bone marrow. We previously identified an increase in immune suppressive myeloid-derived suppressor cells (MDSCs) in GBM patients, which correlated with poor prognosis and was dependent on macrophage migration inhibitory factor (MIF). Here we examine the MIF signaling axis in detail in murine MDSC models, GBM-educated MDSCs and human GBM. We found that the monocytic subset of MDSCs (M-MDSCs), expressed high levels of the MIF cognate receptor CD74 and was localized in the tumor microenvironment. In contrast, granulocytic MDSCs (G-MDSCs) expressed high levels of the MIF non-cognate receptor CXCR2 and showed minimal accumulation in the tumor microenvironment. Furthermore, targeting M-MDSCs with ibudilast, a brain penetrant MIF-CD74 interaction inhibitor, reduced MDSC function and enhanced CD8 T cell activity in the tumor microenvironment. These findings demonstrate the MDSC subsets differentially express MIF receptors and may be leveraged for specific MDSC targeting.

immunology↗