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  • 1
    In: The FASEB Journal, Wiley, Vol. 36, No. S1 ( 2022-05)
    Abstract: Circadian rhythms are ubiquitous in nature, driving many bodily processes and behaviors, including sleep‐wake cycles and feeding patterns over 24 hours. We and others revealed gut microbes and their functional outputs also exhibit diurnal rhythms that are responsive to how much, what, and when food is consumed. These microbial cues are integrated into host circadian networks, serving as key regulators of metabolism. High fat (HF) diet disrupts diurnal microbial oscillations, impacting diet‐induced obesity (DIO). Apart from feeding, host factors that drive microbial oscillations, specifically in the small intestine, are complex and remain poorly understood. We hypothesized that HF diet disrupts coordination of diurnal rhythms between host‐derived antimicrobial peptides, particularly the host C‐type lectin Regenerating islet‐derived 3 gamma ( Reg3γ ), and gut microbial community membership, contributing to DIO and metabolic dysfunction. Results Distal ileal tissue and luminal contents were collected every 4 hours over a 12:12 LD cycle from regular chow (RC) vs. HF‐fed germ‐free (GF) and conventionally raised (CONV) C57Bl/6 age and sex‐matched mice. Ileal tissue gene expression analysis reveals diurnal Reg3γ expression is only observed in RC‐fed, but not HF‐fed, CONV mice. Illumina MiSeq 16S rRNA gene amplicon sequencing of ileal luminal contents indicates that HF diet significantly shifts microbial community membership with a corresponding reduction in oscillations relative to RC. Specific Lactobacillaceae bacteria selected by RC oscillate and exhibit positive correlation with Reg3γ expression, while HF promotes expansion of Clostridiales bacteria that negatively correlate with Reg3γ . Using both in vitro intestinal organoid and in vivo monoassociation of GF mice, we identified that exposure to bacterial strains representative of those selected by RC or HF diet elicit a bi‐directional interaction with Reg3γ ; only RC‐driven Lactobacillus rhamnosus GG (LGG) induces diurnal Reg3γ expression, suggesting a bacteria‐specific effect. While dietary composition remains the primary driver of microbial oscillators, host factors such as Reg3γ provide secondary cues to drive abundance and oscillation of key gut microbes that are essential for host metabolic homeostasis. Conclusions Together, these results demonstrate transkingdom co‐evolved biological rhythms that are primarily influenced by diet, and reciprocal sensor‐effector signals between host and microbial components. The diurnal dynamics of host innate immune factors and specific diet‐induced ileal gut microbes are key for the maintenance of regional intestinal host‐microbe interactions and metabolic homeostasis.
    Type of Medium: Online Resource
    ISSN: 0892-6638 , 1530-6860
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2022
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  • 2
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 84, No. 6_Supplement ( 2024-03-22), p. 1507-1507
    Abstract: Metastasis is a major contributor to cancer morbidity and mortality. However, studying this complex, multi-step, multi-organ process is challenging. There is a pressing need to dissect the contributions of the tumor microenvironment (TME) on this process in a controlled and precise manner. Fortunately, the utilization of microfluidic “organs-on-chips” (OOC) in cancer research is facilitating such investigations. Moreover, by combining organoids and organs-on-chips we can enhance the progress of these studies in a patient specific manner. In this study, we have developed a cancer-on-chip model aimed at investigating early metastatic spread within the colon milieu. To achieve this, we employ colorectal cancer (CRC) cell lines as well as patient-derived CRC organoids chosen from our biorepository to encompass diverse representations across race/ethnicity, sex, and mutational profiles. The tumor cells are introduced into the upper chamber of the OOC model, while human microvascular endothelial cells (HIMECs) are introduced into the lower chamber to establish a tube-like structure resembling a blood vessel. These two chambers are separated by a porous membrane, and the chip is flanked by vacuum chambers to introduce stretch-like motions, simulating peristalsis in the gastrointestinal track. Creating a mechanically dynamic microenvironment facilitates the exploration of neurotransmitters and their impact on tumor cell behavior. Recent studies have suggested that tumor cells may exploit physiological processes, such as neurotransmitter signaling, to their benefit. By utilizing mass spectrometry-based metabolomics we detected dynamic and patient organoid-specific changes in neurotransmitter levels (i.e., serotonin, aspartate, glutamate, γ-aminobutyric acid (GABA)) in the effluent of our CRC-on-chip model. Coupled with live-cell imaging, we discovered tumor cell-derived GABA, a major inhibitory neurotransmitter, serves as an energy source for supporting tumor cell intravasation. This finding was most pronounced in KRAS-mutant tumor cells and further supported by analysis of CRC patient samples from The Cancer Genome Atlas (TCGA) database. We were able to reverse the GABA-mediated invasion effect by inhibiting 4-aminobutyrate aminotransferase (ABAT), the enzyme responsible for GABA catabolism. In summary, our cancer-on-chip model holds promise for exploring various aspects of the metastatic process and uncovering potential therapeutic targets, such as neurotransmitters. Citation Format: Carly Strelez, Rachel Perez, John S. Chlystek, Christopher Cherry, Bethany Haliday, Ah Young Yoon, Curran Shah, Ren X. Sun, Roy Lau, Aaron Schatz, Josh Neman, Heinz Josef-Lenz, Jonathan Katz, Shannon M. Mumenthaler. Involvement of GABAergic signaling in enhanced tumor cell invasion in a mechanically dynamic tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1507.
    Type of Medium: Online Resource
    ISSN: 1538-7445
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2024
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  • 3
    In: Cell Host & Microbe, Elsevier BV, Vol. 30, No. 6 ( 2022-06), p. 809-823.e6
    Type of Medium: Online Resource
    ISSN: 1931-3128
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2022
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  • 4
    In: Communications Engineering, Springer Science and Business Media LLC, Vol. 2, No. 1 ( 2023-03-01)
    Abstract: Frequent monitoring of serum alanine aminotransferase (ALT) activity is essential to prevent drug-induced liver injury (DILI). Current ALT assays are restricted to centralized clinical laboratories, making frequent patient monitoring logistically difficult. To address this, we demonstrated the capability of commercial foundry manufactured silicon nanowire field effect transistor (SiNW-FET) biosensors in a form factor that enables frequent near-patient monitoring. Here, we designed an ALT assay, by coupling the ALT-catalyzed production of pyruvate to the reduction of ferricyanide, enabling both spectrophotometric and electrical measurement of ALT activity. The two methods yield comparable ALT activity detection across a dynamic range wide enough to monitor patients at risk for DILI. This study demonstrates kinetic activity measurement of an endogenous enzyme using uncoupled SiNW-FETs, and commercial manufacturing of SiNW-FET sensor arrays for use in a portable biosensor platform.
    Type of Medium: Online Resource
    ISSN: 2731-3395
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2023
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