Recent evidence indicates that third hand smoke (THS) is present mainly in places where smoking happens regularly but also in places where smoking has been banned but previously happened regularly. THS toxins remain in the contaminated surfaces, are re-emitted and have the ability to react with atmospheric gases to produce dangerous carcinogenic compounds. New evidence regarding the toxicity of THS continues to emerge and has been accumulating for the past 5 years. In order to investigate effects of THS toxins in the liver, I took a molecular and cellular approach by performing multiple cellular assays to study important cellular processes involved in lipid metabolism. The rodent model I used mimics human chronic exposure to THS and separates the effects of SHS (second hand smoke) from THS. I also used different drug treatments and antioxidant treatments to modulate the effects of THS in mice and determine whether oxidative stress plays a key role in the development of THS-induced hepatic steatosis. Using this cellular and molecular approach, I was able to show that THS toxins alter the oxidative stress levels and increase oxidative-stress-mediated damage (protein damage, DNA damage and functional damage) in mice resulting in abnormal lipid metabolism. I was also able to show regulatory pathways, which involve regulators such as AMPK, SIRT1 and SREBP1c, are altered by THS toxins.

Furthermore, THS toxins alter fatty acid metabolism and lead to a decrease in VLDL assembly contributing to accumulation of lipids in the liver. THS-exposed mice have high levels of TG and fatty acids and less ATP production, suggesting these animals are less efficient metabolically compared to the control mice. AICAR treatment resulted in a decrease of fatty acids and TG levels, suggesting that increasing Suirtin 3 (SIRT3), a key regulator of fatty acid metabolism results in less lipid accumulation in the liver. These findings provide evidence of the cellular and molecular basis of THS-induced hepatic steatosis in mice.

Molecular Oxygen is one of the most important molecules in living organisms. Oxygen is the final electron acceptor in the Electron Transport Chain (ETC), which allows organisms to produce ATP. In mammals, oxygen and its chemically similar relatives, reactive oxygen species (ROS) can be used in signaling. For example, one ROS species, H2O2, can signal for apoptosis at low levels. In cancer, increasing the chance that a cell will undergo apoptosis can be useful. New drug targets are necessary for Castration Resistant Prostate Cancer (CRPC). Catalase, an enzyme that detoxifies the cell from H2O2, was shown to be a viable drug target for CRPC by demonstrating tumor reduction in mice. Catalase deficient cells also migrated slower, proliferated slower, and had altered adhesion. On the other hand, too much ROS in mammals can lead to DNA damage, as well as the oxidation of lipids and proteins. An accumulation of damaged DNA, lipids and proteins can lead to long term health impacts. ROS can be produced endogenously or can come from environmental sources like tobacco smoke. A historically underappreciated source of ROS is Third hand Smoke (THS). THS refers to the class of chemicals that reside in or on surfaces after secondhand tobacco smoke has settled and cleared. In this study, THS exposure was shown to increase the relative methylation in mitochondrial DNA. (mtDNA). This could possibly explain the metabolic phenotypes that has been observed in THS exposed mice in previous studies.

Prostate and breast cancer are the second leading cause of cancer death in American men and women respectively. About 1 man in 6 will be diagnosed with prostate cancer and 1 in 8 women will develop invasive breast cancer during their lifetime. Conventional treatments such as surgery and chemotherapy are available but with severe side effects. Recently, evidences from preclinical and clinical studies demonstrate the potential of pomegranate juice (PJ) as natural remedy to fight cancer. I took an integrative approach by using various cellular assays to study important cellular processes for metastasis, Affimetrix gene arrays to study gene expression, microRNA PCR arrays to study the non-coding RNAs, molecules known to be disregulated in cancer cells, and Luminex multiplex immunoassays to study the level of pro-inflammatory cytokines/chemokines. We found that, in addition to causing cell death, PJ increases cell adhesion and decreases cell migration of the prostate and breast cancer cells that do not die. PJ also inhibits the ability of the chemokine CXCL12, together with its receptor CXCR4 are critical in cancer metastasis, to chemoattract cancer cells. Since PJ is a very complex mixture of components, it is important to identify specific components that can mimic the effects of the juice. I found that the combination of a polyphenolic compound (luteolin/L), an antioxidant (ellagic acid/E) and a seed oil component (punicic acid/P), individually and in combination, synergistically affect processes critical for metastasis. L+E+P inhibits growth of prostate and breast cancer cells, their migration and their chemotaxis towards CXCL12. These components also increase the expression of cell adhesion genes and decrease expression of genes involved in cell migration and cell cycle control. The in vivo studies further support the potential of L+E+P. By using the Severely Combined Immuno-Deficiency (SCID) mouse model in which prostate cancer cells were injected subcutaneously, I show that L+E+P inhibits primary tumor growth, angiogenesis and, more importantly, significantly inhibits metastasis. Furthermore, I show that critical cellular processes for metastasis in human endothelial cells are affected by L+E+P. In conclusion, pomegranate and its components can potentially be used to prevent progression and metastasis of prostate and breast cancer.

The skin is the largest organ of the human body. It is barrier that defends and protects the body against environmental assaults and has the important role in maintaining physiological homeostasis, functioning as a highly regulated interface between the outside and inside of the body. Residing on the skin is a microbial community known as the skin microbiota which consists of bacteria, fungi, and viruses. These microbes residing in specific niches of the skin interact with each other and potentially impact the health of the skin through crucial skin-microbe interactions. Research on the resident skin microbiota is ongoing; however, current research suggests that beneficial microbes, commensal microbes, and pathogens all have a role in maintaining healthy skin or causing infection and disease in the skin. When the skin is injured, the human body activates the cutaneous wound healing process to close the wound as quickly and thoroughly as possible to re-establish the protective and defensive roles of the skin. Skin of healthy individuals will heal quickly; however, skin that is afflicted with oxidative stress or inflammation may not heal in a timely manner. When healing is delayed for any number of reasons, the wound may develop into a chronic wound. Chronic wounds are defined as wounds with prolonged healing time greater than four weeks and have very high risk of chronic infections which in turn can further increase healing time. Infected chronic wounds are colonized by bacteria and fungi which can form biofilm, polymeric structures that protect the microbes from the immune system and prolong the infection of the pathogenic microbes. Chronic wounds are difficult to heal as the biofilm present on the wounds are recalcitrant to conventional antimicrobial therapies including antibiotics. To understand how chronic wounds are initiated and what role bacteria play on the skin, I employed a novel chronic wound model in obese, diabetic mice previously developed in our lab. Using this model, I studied how levels of oxidative stress is crucial for the initiation and development of chronic wounds. The level of oxidative stress stimulates bacteria in the wound to produce biofilm soon after injury. I also used to model to study the community of the bacteria that reside on healing and chronic wounds over time. I show that the diversity of the bacteria in healing wounds is very diverse while chronic wounds which also contain biofilms are not. I identified bacterial species associated with either healing wounds or wounds. Lastly, I provide a review on the importance of bacteria in healthy skin, ailing skin and chronic wounds. Taken together, my finding show that oxidative stress is crucial for the initiation and development for chronic wounds and the biofilm that infect them. Further research on the wound-microbe interaction is required to understand the underlying mechanisms that lead to the development of chronic wounds. This knowledge will lead to the discovery and development of new therapies that can heal and prevent chronic wounds.