Biology subjects

Murphy, J. R.

Publications and source records attributed to Murphy, J. R..

4 recordsLinked to original sources

bioRxiv2023

Glutamine metabolism inhibition has dual immunomodulatory and antibacterial activities against Mycobacterium tuberculosis

As one of the most successful human pathogens, Mycobacterium tuberculosis (Mtb) has evolved a diverse array of determinants to subvert host immunity and alter host metabolic patterns. However, the mechanisms of pathogen interference with host metabolism remain poorly understood. Here we show that a novel glutamine metabolism antagonist, JHU083, inhibits Mtb proliferation in vitro and in vivo. JHU083-treated mice exhibit weight gain, improved survival, a 2.5 log lower lung bacillary burden at 35 days post-infection, and reduced lung pathology. JHU083 treatment also initiates earlier T-cell recruitment, increased proinflammatory myeloid cell infiltration, and a reduced frequency of immunosuppressive myeloid cells when compared to uninfected and rifampin-treated controls. Metabolomics analysis of lungs from JHU083-treated Mtb-infected mice revealed reduced glutamine levels, citrulline accumulation suggesting elevated NOS activity, and lowered levels of quinolinic acid which is derived from the immunosuppressive metabolite kynurenine. When tested in an immunocompromised mouse model of Mtb infection, JHU083 lost its therapeutic efficacy suggesting the drugs host-directed effects are likely to be predominant. Collectively, these data reveal that JHU083-mediated glutamine metabolism inhibition results in dual antibacterial and host-directed activity against tuberculosis.

microbiology↗

bioRxiv2020

Effective host-directed therapy for tuberculosis by targeted depletion of myeloid-derived suppressor cells using a diphtheria toxin-based fusion protein

Myeloid-derived suppressor cells (MDSCs) are present in elevated numbers in TB patients and have been found to be permissive for Mycobacterium tuberculosis (Mtb) proliferation. To determine whether depletion of MDSCs may improve host control of TB, we used a novel diphtheria toxin-based fusion protein known as DABIL-4 that targets and depletes IL-4-receptor positive cells. We show that DABIL-4 depletes both PMN-MDSCs and M-MDSC in the mouse TB model, and that it reduces the lung bacillary burden of Mtb. These results indicate that MDSC-depleting therapies targeting the IL4 receptor are beneficial in TB and offer an avenue towards host-directed TB therapy.

microbiology↗

bioRxiv2020

IL-4 receptor targeting as an effective immunotherapy against triple-negative breast cancer

In many solid tumors including triple-negative breast cancer (TNBC), IL-4 receptor (IL-4R) upregulation has been shown to promote cancer cell proliferation, apoptotic resistance, metastatic potential and a Th2 response in the tumor microenvironment (TME). Immunosuppressive cells in the TME including myeloid-derived suppressor cells (MDSCs) and tumor-associated macrophages (TAMs) also express the IL4-R. We hypothesized that selective depletion of IL4-R bearing cells in TNBC may have dual cytotoxic and immunotherapeutic benefit. To selectively target IL-4R+ cells, we genetically constructed, expressed and purified DABIL-4, a fusion protein toxin consisting of the catalytic and translocation domains of diphtheria toxin fused to murine IL-4. We found that DABIL-4 has potent and specific cytotoxic activity against TNBC cells in vitro. In murine TNBC models, DABIL-4 significantly reduced tumor growth, splenomegaly and lung metastases, and this was associated with reductions in MDSC, TAM and regulatory T-cells (Tregs) populations with a concomitant increase in the proportion of IFN{gamma}+ CD8 T-cells. The anti-tumor activity of DABIL-4 was absent in IL-4R KO mice directly implicating IL-4R directed killing as the mechanism of anti-tumor activity. Moreover, NanoString analysis of DABIL-4 treated TNBC tumors revealed marked decline in mRNA transcripts that promote tumorigenesis and metastasis. Our findings demonstrate that DABIL-4 is a potent targeted antitumor agent which depletes both IL-4R bearing tumor cells as well as immunosuppressive cell populations in the TME. STATEMENT OF SIGNIFICANCEIn solid tumors like breast cancer, Interleukin-4 receptor (IL-4R) expression in the tumor microenvironment aids tumor growth and metastasis. IL-4R expression upon host immune cells further dampens antitumor immunity. In this study, we have genetically constructed a fusion protein toxin, DABIL-4, composed of the catalytic and translocation domains of diphtheria toxin and murine IL-4. DABIL-4 showed specific cytotoxicity against triple-negative breast cancer (TNBC) cells in vitro. DABIL-4 also markedly inhibited TNBC tumor growth and metastasis in vivo. The primary activity of DABIL-4 was found to be depletion of IL-4R+ immune cells in combination with direct elimination of tumor cells. In conclusion, DABIL-4 targeting of both tumor and immunosuppressive host cells is a versatile and effective treatment strategy for TNBC.

immunology↗

bioRxiv2018

A second generation IL-2 receptor-targeted diphtheria fusion toxin exhibits anti-tumor activity and synergy with anti-PD-1 in melanoma

Denileukin diftitox (DAB1-389-IL-2, Ontak(R)) is a diphtheria toxin-based fusion protein that depletes CD25-positive cells including regulatory T cells (Tregs) and was approved for the treatment of persistent or recurrent cutaneous T cell lymphoma. However, the clinical use of denileukin diftitox was limited by vascular leak toxicity and production issues related to drug aggregation and purity. We found that a single amino acid substitution (V6A) in a motif associated with vascular leak induction yields a fully active, second-generation biologic, s-DAB1-386-IL-2(V6A), which elicits 50-fold less HUVEC monolayer permeation and is 3.7-fold less lethal to mice by LD50 analysis than s-DAB1-386-IL-2 Additionally, to overcome aggregation problems, we developed a novel production method for the fusion toxin using Corynebacterium diphtheriae that secretes fully-folded, biologically active, monomeric s-DAB1-386-IL-2 into the culture medium. Using the poorly immunogenic mouse B16F10 melanoma model, we initiated treatment 7 days after tumor challenge and observed that, while both s-DAB1-386-IL-2(V6A) and s-DAB1-386-IL-2 are inhibitors of tumor growth, the capacity to treat with higher doses of s-DAB1-386-IL-2(V6A) could provide a superior activity window. In a sequential dual therapy study in tumors that have progressed for 10 days both s-DAB1-386-IL-2(V6A) and s-DAB1-386-IL-2 given prior to checkpoint inhibition with anti-PD-1 antibodies inhibited tumor growth, while either drug given as monotherapy had less effect. s-DAB1-386-IL-2(V6A), a fully monomeric protein with reduced vascular leak, is a second-generation diphtheria toxin-based fusion protein with promise as a cancer immunotherapeutic both alone and in conjunction with PD-1 blockade.\n\nSignificance StatementRegulatory T cells (Tregs) infiltrate tumors in various cancers and promote an immunosuppressive microenvironment that hinders anti-tumor immunity. Denileukin diftitox, a diphtheria toxin-based fusion protein that depletes Tregs, was approved for the treatment of T cell malignancies, but its clinical use was limited due to the presence of protein aggregates and toxicity associated with vascular leakage. Here we report the production of a second generation IL-2 receptor-targeted, fully-folded, monomeric diphtheria fusion toxin, and a V6A mutant variant which showed reduced vascular leak in vitro and reduced lethality in mice. In a mouse model of melanoma, we found significant decrease in tumor growth associated with reduction in Tregs when the protein was tested as monotherapy or in combination with checkpoint blockade.

cancer biology↗