School of Medicinehttp://hdl.handle.net/10713/332024-03-28T06:16:06Z2024-03-28T06:16:06ZPD-L1 regulation by Dual Oxygenase 2 (DUOX2), a Reactive Oxygen Species (ROS) producing enzyme in gastric cancers.Martins, Mariana B.Carrier, Francehttp://hdl.handle.net/10713/215822024-03-28T05:25:32Z2024-04-05T00:00:00ZPD-L1 regulation by Dual Oxygenase 2 (DUOX2), a Reactive Oxygen Species (ROS) producing enzyme in gastric cancers.
Martins, Mariana B.; Carrier, France
Immune checkpoint inhibitors have shown outstanding activities
in some cancers, but their efficacy is rather variable with limited
long-term response in most patients while others do not respond
well or even develop resistances. The oxidative state of the tumor
and its microenvironment plays a critical role in this response
and highlights the importance of better understanding the role of
redox enzymes in response to immunotherapy. In fact, Reactive
Oxygen Species (ROS) effectors can either up or down regulate
PD-L1 expression depending on their targets and mechanisms of
action. Our data indicate that DUOX2, an NADPH enzyme involved
in the production of H2O2, is expressed in about forty percent of
human gastric cancers and is significantly increased in
esophageal cancers. Moreover, DUOX2 expression in human
gastric and esophageal cancer cells corresponds to down
regulation of the immune checkpoint PD-L1. Conversely, down
regulation of DUOX2 increases PD-L1, HIF-1a and c-Myc
expression in these cells. To better understand the role of
DUOX2 in the production of ROS and how it interferes with the
expressions of HIF-1a and PD-L1, we also evaluated its effects on
the ROS scavenger glutathione (GSH) and the ROS generating
Ceramide in cells expressing or not DUOX2. The down regulation
of DUOX2 reduced by more than half Ceramide levels and
significantly increased GSH levels. This is consistent with the
known effect of H2O2 on Ceramide generation through
sphingomyelin hydrolysis and H2O2 inhibitory effect on HIF-1a
binding and accumulation of HIF-1a protein. Because HIF-1a is a
known regulator of PD-L1, DUOX2 expression on some tumors
could thus interfere with PD-L1 expression through generation of
H2O2. Moreover, because HIF-1a and PD-L1 expression contribute
to radio-resistance, DUOX2 expression could sensitize cancer
cells to radiation therapy. On the other hand, tumors lacking
DUOX2 expression would be expected to be more sensitive to
immunotherapy targeting PD-1 and/or PD-L1. DUOX2 expression
thus appears to hold significant potential as a valuable biomarker
to guide therapeutic decisions regarding radiation or immuno-
therapy
AACR Annual Meeting, April 5-10, 2024
2024-04-05T00:00:00ZAltered Gene Expression Profiles and Immune Responses in a Murine Model of a Non-lethal Flame Burn with Pseudomonas aeruginosa InfectionKambouris, Adrienne Reneehttp://hdl.handle.net/10713/215672024-03-22T02:18:23Z2023-01-01T00:00:00ZAltered Gene Expression Profiles and Immune Responses in a Murine Model of a Non-lethal Flame Burn with Pseudomonas aeruginosa Infection
Kambouris, Adrienne Renee
Humanity has lived with fires for millennia, but combat, domestic use, and recent wildfires have increased the risk of burn injuries. Worldwide, over 100,000 deaths occur each year due to burns. If these patients survive the burn wound itself, the most common causes of death are multiorgan failure and sepsis, often caused by infection by Pseudomonas aeruginosa (PA). Utilizing a 10% total body surface area (TBSA) non-lethal flame burn model in mice, a superimposed infection of PA caused 100% mortality within 36 hours post-burn. This effect was transient, as infection 72 hours post-burn resulted in survival. The hypothesis was that this mortality could be linked to changes in gene expression that altered host-pathogen interaction. NanoString™, a system that allowed us to develop a custom panel of probes, was utilized to measure Mus musculus and PA gene transcripts simultaneously in each sample. Sampling from the blood, spleen, liver, and skin, gene expression in the burn and infection condition (B/I) was significantly different in each tissue when compared to mice that were burned alone, infected alone, and neither burned nor infected (Sham). The expression of the anti-inflammatory gene, Il10 is significantly increased over time in the spleen; administering anti-IL-10 antibodies delayed mortality by one day. While Arg1 and Nos2 gene expression were not significantly altered, administering arginine concurrently with PA restored survival in our mouse model, likely due to an inhibition of both PA motility and growth. We also hypothesized that burn-induced neutrophil dysfunction allowed for PA proliferation. Neutrophils isolated from the seroma of burned mice had a decreased ability to produce antibacterial reactive oxygen species (ROS) compared to neutrophils in the circulation of the same mice. Surprisingly, naïve neutrophils in the circulation of burned mice had a decreased ability to kill PA, possibly due to their premature ROS production induced by a burn-generated DAMP, HMGB1, present in the serum of burned but not Sham mice. In conclusion, a non-lethal burn injury is sufficient to induce multi-faceted changes in the murine immune system that results in an increased susceptibility to lethal PA superinfection.
University of Maryland, Baltimore School of Medicine. Ph.D. 2023.
2023-01-01T00:00:00ZPim kinase inhibitor enhances FLT3 inhibitor gilteritinib efficacy through GSK-3β activation and GSK-3β-mediated c-Myc and Mcl-1 proteasomal degradationLee, Jonellehttp://hdl.handle.net/10713/215662024-03-22T02:18:03Z2023-01-01T00:00:00ZPim kinase inhibitor enhances FLT3 inhibitor gilteritinib efficacy through GSK-3β activation and GSK-3β-mediated c-Myc and Mcl-1 proteasomal degradation
Lee, Jonelle
Acute myeloid leukemia (AML) with fms-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD) has poor outcomes. FLT3-ITD drives constitutive and aberrant FLT3 signaling, activating STAT5 and upregulating the downstream oncogenic serine/threonine kinase Pim-1. FLT3 inhibitors have limited clinical efficacy. We previously showed that concurrent Pim and FLT3 inhibition increases apoptosis induction in FLT3-ITD-expressing cells through post-translational downregulation of Mcl-1. Here we further elucidate the mechanisms of action of this dual targeting strategy. Protein expression and turnover, cytotoxicity and apoptosis were measured in FLT3-ITD-expressing cell lines and AML blasts treated with FLT3 inhibitor gilteritinib and/or Pim inhibitors AZD1208 or TP-3654. Pim and FLT3 inhibitor co-treatment decreased c-Myc protein, prior to Mcl-1, increased turnover of both proteins, rescued by proteasome inhibition, dephosphorylated (activated) GSK-3β, and increased apoptosis and in vivo efficacy. GSK-3β inhibition prevented c-Myc and Mcl-1 downregulation and apoptosis. Pim and FLT3 inhibitor co-treatment of Ba/F3-ITD cells infected with T58A c-Myc or S159A Mcl-1 plasmids, preventing phosphorylation at these sites, did not downregulate these proteins, increase their turnover or induce apoptosis, consistent with GSK-3β activation and c-Myc T58 and Mcl-1 S159 phosphorylation as the mechanism of combination treatment. These data further support GSK-3β activation as a therapeutic strategy in FLT3-ITD AML.
University of Maryland, Baltimore School of Medicine. Ph.D. 2023.
2023-01-01T00:00:00ZRole of Social Determinants of Health on the HIV Testing and Treatment Cascade in NigeriaMohanty, Kareshmahttp://hdl.handle.net/10713/215652024-03-22T02:18:30Z2023-01-01T00:00:00ZRole of Social Determinants of Health on the HIV Testing and Treatment Cascade in Nigeria
Mohanty, Kareshma
Introduction:
The Joint United Nations Programme on HIV and AIDS proposed that to achieve epidemic control of HIV by 2025; 95% of all people living with HIV are aware of their status, 95% of people diagnosed with HIV receive sustained antiretroviral therapy (ART), and 95% of all people on ART are virally suppressed (VLS). The 2018 Nigeria HIV/AIDS Indicator and Impact Survey (NAIIS) found that in Nigeria, while only 47% knew their status, 96% had received ART, and 81% had achieved VLS.
Social determinants of health (SDH), like wealth index (WI), have been shown to play a significant role in HIV in western countries, but the evidence has been limited and mixed in Nigeria. Identifying political, social, cultural, demographic, economic, and behavioral indicators of SDH, can better explain and address the disparities in the HIV epidemic, especially in the testing and treatment cascade, that are preventing the UNAIDS targets from being met in Nigeria.
Objective:
Examine the role of singular and composite indicators of SDH on the 95-95-95 targets: HIV testing, receipts of ART, and VLS in people living with HIV in Nigeria. Additionally, examine if wealth modifies the relationship between SDH indicators and the three 95 targets.
Methods:
Using the World Health Organization-SDH framework and Factor Analysis, I constructed composite indicators of SDH for Nigeria from various population-level survey data sources. Scores from the sub-indices and Global Terrorism Index were categorized as low, medium, and high, and individual or states were assigned one of these categories. Subsequently, I examined the association of the composite and singular SDH factors with HIV testing, receipt of ART, and achievement of VLS through survey-weighted multivariable logistic regression. Additionally, I examined the significance of the SDH indicators with the testing and treatment outcomes, by each of the wealth quintiles.
Results:
Out of the seven sub-indices constructed, only Access to Public Services, Crime & Conflict, Government Corruption, and Government Performance met the internal reliability criterion (Cronbach alpha > 0.7). Global Terrorism Index was constructed based on the prescribed methodology. When examining HIV testing, the first target in the 95-95-95 UNAIDS strategy, medium levels of Government Corruption, lower/medium Government Performance, and high Terrorism was associated with lower testing. Unemployment, living in rural areas, and married before 18 years of age were significantly associated with lower odds of HIV testing. For receipt of ART, second 95-95-95 target, low/medium treatment coverage was associated with lower odds of being on treatment. Younger age, male sex, being single, and living in rural areas were the singular factors associated with lower receipt of ART. Finally, for the third 95-95-95 target, only singular SDH, like lack of condom usage during sex, CD4 count (<500), and ethnic languages were associated with lower VLS. Wealth modified the relationship between the social determinants and HIV testing and treatment, but the role was weak. Wealth may increase the gap between the lowest and highest wealth index strata; HIV-related disparities experienced might be more pronounced between the two ends.
Conclusion:
Understanding and addressing structural determinants like political stability, terrorism, gender equality, accessibility to public services, and treatment facility coverage, rather than individual-level behavioral factors, could help Nigeria achieve the 95-95-95 targets.
University of Maryland, Baltimore School of Medicine, Ph.D. 2023.
2023-01-01T00:00:00Z