Stacy-Ann Miller

Preliminary studies on differential expression of auditory functional genes in the brain after repeated blast exposures

The mechanisms of central auditory processing involved in auditory/vestibular injuries and subsequent tinnitus and hearing loss in Active Duty servicemembers exposed to blast are not currently known. We analyzed the expression of hearing-related genes in different regions of the brain 6 h after repeated blast exposures in mice. Preliminary data showed that the expression of the deafness-related genes otoferlin and otoancorin was significantly changed in the hippocampus after blast exposures. Differential expression of cadherin and protocadherin genes, which are involved in hearing impairment, was observed in the hippocampus, cerebellum, frontal cortex, and midbrain after repeated blasts. A series of calcium-signaling genes that are known to be involved in auditory signal processing were also found to be significantly altered after repeated blast exposures. The hippocampus and midbrain showed significant increase in the gene expression of hearing loss-related antioxidant enzymes. Histopathology of the auditory cortex showed more significant injury in the inner layer compared to the outer layer. In summary, mice exposed to repeated blasts showed injury to the auditory cortex and significant alterations in multiple genes in the brain known to be involved in age- or noise-induced hearing impairment.

Estrogen receptor-dependent genomic expression profiles in breast cancer cells in response to fatty acids.

Context: The estrogen receptor (ER) status in breast cancer plays a major role in the progression and metastatic potential of breast cancer in women. Breast cancer cells lacking the ER are usually more advanced and more difficult to treat than ER+ breast cancer cells. ER− women have more advanced breast cancer at the time of diagnosis than ER+ women. ER− breast cancer cells in women, regardless of age, are more likely to have tumor Grade III or IV with fewer Grade I and II tumor stages combined for each individual stage group. Studies have suggested a strong correlation between fat intake and the elevated risk of ER+ breast cancer cells. Materials and Methods: We studied the role of ER status on the gene expression in breast cancer cells in response to omega-3 and omega-6 fatty acids using microarrays. We have studied gene expression patterns in 8 breast cancer cell lines (4 ER− and 4 ER+) in response to Eicosapentanoic (EPA) and Arachidonic (AA) acids. Statistical Analysis: Analysis of Variance (ANOVA) t-test analysis was carried out to identify genes differentially expressed between the two groups. Results: We identified genes which were significantly correlated with the ER status when breast cancer cells were treated with these fatty acids. Conclusion: We have determined ER-related gene expression patterns in breast cancer cells in response to fatty acids. Additional studies of these biomarkers may enlighten the importance of the ER status on the mechanistic and therapeutic roles of fatty acids in breast cancer.

An integrated omics analysis: impact of microgravity on host response to lipopolysaccharide in vitro

BackgroundMicrogravity facilitates the opportunistic infections by augmenting the pathogenic virulence and suppressing the host resistance. Hence the extraterrestrial infections may activate potentially novel bionetworks different from the terrestrial equivalent, which could only be probed by investigating the host-pathogen relationship with a minimum of terrestrial bias.ResultsWe customized a cell culture module to expose human endothelial cells to lipopolysaccharide (LPS). The assay was carried out onboard the STS-135 spaceflight, and a concurrent ground study constituted the baseline. Transcriptomic investigation revealed a possible immune blunting in microgravity suppressing in particular Lbp, MyD88 and MD-2, which encode proteins responsible for early LPS uptake. Certain cytokines, such as IL-6 and IL-8, surged in response to LPS insult in microgravity, as suggested by the proteomics study. Contrasting proteomic expressions of B2M, TIMP-1 and VEGRs suggested impaired pro-survival adaptation and healing mechanisms. Differential expression of miR-200a and miR-146b suggested the susceptibility of hosts in spaceflight to oxidative stress and further underscored the influence of microgravity on the immunity.ConclusionsA molecular interpretation explaining the etiology of the microgravitational impact on the host-pathogen relationship elucidated comprehensive immune blunting of the host cells responding to LPS challenges. Longer LPS exposure prompted a delayed host response, potentially ineffectual in preventing pathogens from opportunistic invasion. Significant consequences include the subsequent failure in recruiting the growth factors and a debilitated apoptosis. Follow up studies with larger sample size are warranted.

Altered gene expression in asymptomatic SHIV-infected rhesus macaques (Macacca mulatta).

Simian-Human immunodeficiency virus is a chimeric virus which, in rhesus macaques (Macacca mulatta) closely imitates immunodeficiency virus infection in human (HIV). A relatively new way to study pathogenesis of viral infection is to study alterations in host gene expression induced by the virus. SHIV infection with certain strains does not result in clinical signs. We hypothesized that alterations in gene expression relating to the immune system would be present in SHIV-infected animals despite the lack of clinical signs. Splenic tissue from four adult male Indian-origin Rhesus monkeys serologically positive for non-pathogenic SHIV 89.6 was processed by cDNA microarray analysis. Results were compared with the corresponding outcome using splenic tissues from four unexposed adult male Rhesus monkeys. Subsequent gene analysis confirmed statistically significant variations between control and infected samples. Interestingly, SHIV-infected monkeys exhibited altered expression in genes related to apoptosis, signal transduction, T and B lymphocyte activation and importantly, to immune regulation. Although infected animals appeared asymptomatic, our study demonstrated that SHIV-infected monkeys cannot reliably be used in studies of other infectious agents as their baseline gene expression differs from that of normal Rhesus monkeys. The gene expression differences in SHIV-infected animals relative to uninfected animals offer additional clues to the pathogenesis of altered immune function in response to secondary infection.

Characterization of the interaction of staphylococcal enterotoxin B with CD1d expressed in human renal proximal tubule epithelial cells

BackgroundParticipation of renal cells in the pathogenesis of staphylococcal enterotoxin B (SEB) is critical for late cleansing and sequestration of the antigens facilitated by CD1d mediated antigen sensing and recognition. This is a noted deviation from the typical antigen recognition process that recruits the major histocompatibility complex class II (MHC II) molecules. The immunological importance of CD1d is underscored by its influences on the performances of natural killer T-cells and thereby mediates the innate and adaptive immune systems.ResultsUsing diffraction-based dotReady™ immunoassays, the present study showed that SEB directly and specifically conjugated to CD1d. The specificity of the conjugation between SEB and CD1d expressed on human renal proximal tubule epithelial cells (RPTEC) was further established by selective inhibition of CD1d prior to its exposure to SEB. We found that SEB induced the expression of CD1d on the cell surface prompting a rapid conjugation between them. The mRNA transcripts encoding CD1d remained elevated potentially after completing the antigen cleansing process.ConclusionMolecular targets associated with the delayed pathogenic response have essential therapeutic values. Particularly in the event of bioterrorism, the caregivers are typically able to intervene much later than the toxic exposures. Given circumstances mandate a paradigm shift from the conventional therapeutic strategy that counts on targeting the host markers responding to the early assault of pathogens. We demonstrated the role of CD1d in the late stage of pathogen recognition and cleansing, and thereby underscored its clinical potential in treating bioweaponizable antigens, such as Staphylococcal enterotoxin B (SEB).

Temporal Progression of Pneumonic Plague in Blood of Nonhuman Primate: A Transcriptomic Analysis

Early identification of impending illness during widespread exposure to a pathogenic agent offers a potential means to initiate treatment during a timeframe when it would be most likely to be effective and has the potential to identify novel therapeutic strategies. The latter could be critical, especially as antibiotic resistance is becoming widespread. In order to examine pre-symptomatic illness, African green monkeys were challenged intranasally with aerosolized Yersinia pestis strain CO92 and blood samples were collected in short intervals from 45 m till 42 h post-exposure. Presenting one of the first genomic investigations of a NHP model challenged by pneumonic plague, whole genome analysis was annotated in silico and validated by qPCR assay. Transcriptomic profiles of blood showed early perturbation with the number of differentially expressed genes increasing until 24 h. By then, Y. pestis had paralyzed the host defense, as suggested by the functional analyses. Early activation of the apoptotic networks possibly facilitated the pathogen to overwhelm the defense mechanisms, despite the activation of the pro-inflammatory mechanism, toll-like receptors and microtubules at the port-of-entry. The overexpressed transcripts encoding an early pro-inflammatory response particularly manifested in active lymphocytes and ubiquitin networks were a potential deviation from the rodent models, which needs further verification. In summary, the present study recognized a pattern of Y. pestis pathogenesis potentially more applicable to the human system. Independent validation using the complementary omics approach with comprehensive evaluation of the organs, such as lungs which showed early bacterial infection, is essential.

Correction: Temporal Progression of Pneumonic Plague in Blood of Nonhuman Primate: A Transcriptomic Analysis

The sixth author, Nabarun Chakraborty, should be noted as contributing equally to this work.