Examining trends in the diversity of the U.S. National Institutes of Health participating and funded workforce.

Here, we use recent U.S. National Institutes of Health (NIH) data to document trends in the NIH-funded workforce over time. Consistent with previous studies that were initiated by NIH, we find that the number of scientists funded on competing R01-equivalent (R01 Eq.) and research project grants (RPGs) increased 2-5% per year between 2009 and 2016. Primary beneficiaries of this growth were experienced investigators (Exp), whereas the share of funding awarded to early-stage investigators (ESIs) and new investigators (NIs) declined. The decline occurred even after NIH instituted the New and Early-Stage Investigator policy in 2009. When we evaluate the investigator pool, we find that women and racial and ethnic minorities represent a higher percentage of NIs and ESIs relative to Exp. Thus, trends of diminishing support for NIs and ESIs may negatively impact the diversity of the current and future biomedical research workforce. We find some recent gains among women and Hispanics as part of the applicant and awardee pool for both R01 Eq. and RPGs, but significant, large gaps persist among nationally underrepresented racial minorities. Our findings suggest a need to prioritize investments and support of ESIs and NIs, groups in which women and racial and ethnic minorities represent a larger proportion of the applicant pool, to enhance diversity in the NIH-funded workforce.-Nikaj, S., Roychowdhury, D., Lund, P. K., Matthews, M., Pearson, K. Examining trends in the diversity of the U.S. National Institutes of Health participating and funded workforce.

Functional Transcriptomics in Diverse Intestinal Epithelial Cell Types Reveals Robust MicroRNA Sensitivity in Intestinal Stem Cells to Microbial Status.

Gut microbiota play an important role in regulating the development of the host immune system, metabolic rate, and at times, disease pathogenesis. The factors and mechanisms that mediate interactions between microbiota and the intestinal epithelium are not fully understood. We provide novel evidence that microbiota may control intestinal epithelial stem cell (IESC) proliferation in part through microRNAs (miRNAs). We demonstrate that miRNA profiles differ dramatically across functionally distinct cell types of the mouse jejunal intestinal epithelium and that miRNAs respond to microbiota in a highly cell type-specific manner. Importantly, we also show that miRNAs in IESCs are more prominently regulated by microbiota compared with miRNAs in any other intestinal epithelial cell subtype. We identify miR-375 as one miRNA that is significantly suppressed by the presence of microbiota in IESCs. Using a novel method to knockdown gene and miRNA expression ex vivo enteroids, we demonstrate that we can knock down gene expression in Lgr5+ IESCs. Furthermore, when we knock down miR-375 in IESCs, we observe significantly increased proliferative capacity. Understanding the mechanisms by which microbiota regulate miRNA expression in IESCs and other intestinal epithelial cell subtypes will elucidate a critical molecular network that controls intestinal homeostasis and, given the heightened interest in miRNA-based therapies, may offer novel therapeutic strategies in the treatment of gastrointestinal diseases associated with altered IESC function.

miR-30 Family Controls Proliferation and Differentiation of Intestinal Epithelial Cell Models by Directing a Broad Gene Expression Program That Includes SOX9 and the Ubiquitin Ligase Pathway.

Proliferation and differentiation of intestinal epithelial cells (IECs) occur in part through precise regulation of key transcription factors, such as SOX9. MicroRNAs (miRNAs) have emerged as prominent fine-tuners of transcription factor expression and activity. We hypothesized that miRNAs, in part through the regulation of SOX9, may mediate IEC homeostasis. Bioinformatic analyses of the SOX9 3'-UTR revealed highly conserved target sites for nine different miRNAs. Of these, only the miR-30 family members were both robustly and variably expressed across functionally distinct cell types of the murine jejunal epithelium. Inhibition of miR-30 using complementary locked nucleic acids (LNA30bcd) in both human IECs and human colorectal adenocarcinoma-derived Caco-2 cells resulted in significant up-regulation of SOX9 mRNA but, interestingly, significant down-regulation of SOX9 protein. To gain mechanistic insight into this non-intuitive finding, we performed RNA sequencing on LNA30bcd-treated human IECs and found 2440 significantly increased genes and 2651 significantly decreased genes across three time points. The up-regulated genes are highly enriched for both predicted miR-30 targets, as well as genes in the ubiquitin-proteasome pathway. Chemical suppression of the proteasome rescued the effect of LNA30bcd on SOX9 protein levels, indicating that the regulation of SOX9 protein by miR-30 is largely indirect through the proteasome pathway. Inhibition of the miR-30 family led to significantly reduced IEC proliferation and a dramatic increase in markers of enterocyte differentiation. This in-depth analysis of a complex miRNA regulatory program in intestinal epithelial cell models provides novel evidence that the miR-30 family likely plays an important role in IEC homeostasis.

IGF1 stimulates crypt expansion via differential activation of 2 intestinal stem cell populations.

Insulin-like growth factor 1 (IGF1) has potent trophic effects on normal or injured intestinal epithelium, but specific effects on intestinal stem cells (ISCs) are undefined. We used Sox9-enhanced green fluorescent protein (EGFP) reporter mice that permit analyses of both actively cycling ISCs (Sox9-EGFP(Low)) and reserve/facultative ISCs (Sox9-EGFP(High)) to study IGF1 action on ISCs in normal intestine or during crypt regeneration after high-dose radiation-induced injury. We hypothesized that IGF1 differentially regulates proliferation and gene expression in actively cycling and reserve/facultative ISCs. IGF1 was delivered for 5 days using subcutaneously implanted mini-pumps in uninjured mice or after 14 Gy abdominal radiation. ISC numbers, proliferation, and transcriptome were assessed. IGF1 increased epithelial growth in nonirradiated mice and enhanced crypt regeneration after radiation. In uninjured and regenerating intestines, IGF1 increased total numbers of Sox9-EGFP(Low) ISCs and percentage of these cells in M-phase. IGF1 increased percentages of Sox9-EGFP(High) ISCs in S-phase but did not expand this population. Microarray revealed that IGF1 activated distinct gene expression signatures in the 2 Sox9-EGFP ISC populations. In vitro IGF1 enhanced enteroid formation by Sox9-EGFP(High) facultative ISCs but not Sox9-EGFP(Low) actively cycling ISCs. Our data provide new evidence that IGF1 activates 2 ISC populations via distinct regulatory pathways to promote growth of normal intestinal epithelium and crypt regeneration after irradiation.

Obesity and intestinal epithelial deletion of the insulin receptor, but not the IGF 1 receptor, affect radiation-induced apoptosis in colon.

Current views suggest that apoptosis eliminates genetically damaged cells that may otherwise form tumors. Prior human studies link elevated insulin and reduced apoptosis to risk of colorectal adenomas. We hypothesized that hyperinsulinemia associated with obesity would lead to reduced colon epithelial cell (CEC) apoptosis after radiation and that this effect would be altered by deletion of the insulin-like growth factor (IGF) 1 receptor (IGF1R) or the insulin receptor (IR). Mice with villin-Cre-mediated IGF1R or IR deletion in CECs and floxed littermates were fed a high-fat diet to induce obesity and hyperinsulinemia or control low-fat chow. Mice were exposed to 5-Gy abdominal radiation to induce DNA damage and euthanized 4 h later for evaluation of apoptosis by localization of cleaved caspase-3. Obese mice exhibited decreased apoptosis of genetically damaged CECs. IGF1R deletion did not affect CEC apoptosis in lean or obese animals. In contrast, IR loss increased CEC apoptosis in both diet groups but did not prevent antiapoptotic effects of obesity. Levels of p53 protein were significantly reduced in CECs of obese mice with intact IR but increased in both lean and obese mice without IR. Levels of mRNAs encoding proapoptotic Perp and the cell cycle inhibitor Cdkn1b/p27 were reduced in CECs of obese mice and increased in lean mice lacking IR. Together, our studies provide novel evidence for antiapoptotic roles of obesity and IR, but not IGF1R, in colonic epithelium after DNA damage. However, neither IR nor IGF1R deletion prevented a reduction in radiation-induced CEC apoptosis during obesity and hyperinsulinemia.

Deletion of intestinal epithelial insulin receptor attenuates high-fat diet-induced elevations in cholesterol and stem, enteroendocrine, and Paneth cell mRNAs.

The insulin receptor (IR) regulates nutrient uptake and utilization in multiple organs, but its role in the intestinal epithelium is not defined. This study developed a mouse model with villin-Cre (VC) recombinase-mediated intestinal epithelial cell (IEC)-specific IR deletion (VC-IR(Δ/Δ)) and littermate controls with floxed, but intact, IR (IR(fl/fl)) to define in vivo roles of IEC-IR in mice fed chow or high-fat diet (HFD). We hypothesized that loss of IEC-IR would alter intestinal growth, biomarkers of intestinal epithelial stem cells (IESC) or other lineages, body weight, adiposity, and glucose or lipid handling. In lean, chow-fed mice, IEC-IR deletion did not affect body or fat mass, plasma glucose, or IEC proliferation. In chow-fed VC-IR(Δ/Δ) mice, mRNA levels of the Paneth cell marker lysozyme (Lyz) were decreased, but markers of other differentiated lineages were unchanged. During HFD-induced obesity, IR(fl/fl) and VC-IR(Δ/Δ) mice exhibited similar increases in body and fat mass, plasma insulin, mRNAs encoding several lipid-handling proteins, a decrease in Paneth cell number, and impaired glucose tolerance. In IR(fl/fl) mice, HFD-induced obesity increased circulating cholesterol; numbers of chromogranin A (CHGA)-positive enteroendocrine cells (EEC); and mRNAs encoding Chga, glucose-dependent insulinotrophic peptide (Gip), glucagon (Gcg), Lyz, IESC biomarkers, and the enterocyte cholesterol transporter Scarb1. All these effects were attenuated or lost in VC-IR(Δ/Δ) mice. These results demonstrate that IEC-IR is not required for normal growth of the intestinal epithelium in lean adult mice. However, our findings provide novel evidence that, during HFD-induced obesity, IEC-IR contributes to increases in EEC, plasma cholesterol, and increased expression of Scarb1 or IESC-, EEC-, and Paneth cell-derived mRNAs.

Transcriptional corepressor MTG16 regulates small intestinal crypt proliferation and crypt regeneration after radiation-induced injury.

Myeloid translocation genes (MTGs) are transcriptional corepressors implicated in development, malignancy, differentiation, and stem cell function. While MTG16 loss renders mice sensitive to chemical colitis, the role of MTG16 in the small intestine is unknown. Histological examination revealed that Mtg16(-/-) mice have increased enterocyte proliferation and goblet cell deficiency. After exposure to radiation, Mtg16(-/-) mice exhibited increased crypt viability and decreased apoptosis compared with wild-type (WT) mice. Flow cytometric and immunofluorescence analysis of intestinal epithelial cells for phospho-histone H2A.X also indicated decreased DNA damage and apoptosis in Mtg16(-/-) intestines. To determine if Mtg16 deletion affected epithelial cells in a cell-autonomous fashion, intestinal crypts were isolated from Mtg16(-/-) mice. Mtg16(-/-) and WT intestinal crypts showed similar enterosphere forming efficiencies when cultured in the presence of EGF, Noggin, and R-spondin. However, when Mtg16(-/-) crypts were cultured in the presence of Wnt3a, they demonstrated higher enterosphere forming efficiencies and delayed progression to mature enteroids. Mtg16(-/-) intestinal crypts isolated from irradiated mice exhibited increased survival compared with WT intestinal crypts. Interestingly, Mtg16 expression was reduced in a stem cell-enriched population at the time of crypt regeneration. This is consistent with MTG16 negatively regulating regeneration in vivo. Taken together, our data demonstrate that MTG16 loss promotes radioresistance and impacts intestinal stem cell function, possibly due to shifting cellular response away from DNA damage-induced apoptosis and towards DNA repair after injury.

Insulin receptor isoform switching in intestinal stem cells, progenitors, differentiated lineages and tumors: evidence that IR-B limits proliferation.

Despite evidence for the impact of insulin on intestinal epithelial physiology and pathophysiology, the expression patterns, roles, and regulation of insulin receptor (IR) and IR isoforms in the intestinal epithelium are not well characterized. IR-A is thought to mediate the proliferative effects of insulin or insulin growth factors (IGFs) in fetal or cancer cells. IR-B is considered to be the metabolic receptor for insulin in specialized tissues. This study used a novel Sox9-EGFP reporter mouse that permits isolation of intestinal epithelial stem cells (IESCs), progenitors, enteroendocrine cells and differentiated lineages, the Apc(Min/+) mouse model of precancerous adenoma and normal human intestinal and colorectal cancer (CRC) cell lines. We tested the hypothesis that there is differential expression of IR-A or IR-B in stem and tumor cells versus differentiated intestinal epithelial cells (IECs) and that IR-B impacts cell proliferation. Our findings provide evidence that IR-B expression is significantly lower in highly proliferative IESCs and progenitor cells versus post-mitotic, differentiated IECs and in subconfluent and undifferentiated versus differentiated Caco-2 cells. IR-B is also reduced in Apc(Min/+) tumors and highly tumorigenic CRC cells. These differences in IR-B were accompanied by altered levels of mRNAs encoding muscleblind-like 2 (MBNL2), a known regulator of IR alternative splicing. Forced IR-B expression in subconfluent and undifferentiated Caco-2 cells reduced proliferation and increased biomarkers of differentiation. Our findings indicate that the impact of insulin on different cell types in the intestinal epithelium might differ depending on relative IR-B IR-A expression levels and provide new evidence for the roles of IR-B to limit proliferation of CRC cells.

Activation of two distinct Sox9-EGFP-expressing intestinal stem cell populations during crypt regeneration after irradiation.

Recent identification of intestinal epithelial stem cell (ISC) markers and development of ISC reporter mice permit visualization and isolation of regenerating ISCs after radiation to define their functional and molecular phenotypes. Previous studies in uninjured intestine of Sox9-EGFP reporter mice demonstrate that ISCs express low levels of Sox9-EGFP (Sox9-EGFP Low), whereas enteroendocrine cells (EEC) express high levels of Sox9-EGFP (Sox9-EGFP High). We hypothesized that Sox9-EGFP Low ISCs would expand after radiation, exhibit enhanced proliferative capacities, and adopt a distinct gene expression profile associated with rapid proliferation. Sox9-EGFP mice were given 14 Gy abdominal radiation and studied between days 3 and 9 postradiation. Radiation-induced changes in number, growth, and transcriptome of the different Sox9-EGFP cell populations were determined by histology, flow cytometry, in vitro culture assays, and microarray. Microarray confirmed that nonirradiated Sox9-EGFP Low cells are enriched for Lgr5 mRNA and mRNAs enriched in Lgr5-ISCs and identified additional putative ISC markers. Sox9-EGFP High cells were enriched for EEC markers, as well as Bmi1 and Hopx, which are putative markers of quiescent ISCs. Irradiation caused complete crypt loss, followed by expansion and hyperproliferation of Sox9-EGFP Low cells. From nonirradiated intestine, only Sox9-EGFP Low cells exhibited ISC characteristics of forming organoids in culture, whereas during regeneration both Sox9-EGFP Low and High cells formed organoids. Microarray demonstrated that regenerating Sox9-EGFP High cells exhibited transcriptomic changes linked to p53-signaling and ISC-like functions including DNA repair and reduced oxidative metabolism. These findings support a model in which Sox9-EGFP Low cells represent active ISCs, Sox9-EGFP High cells contain radiation-activatable cells with ISC characteristics, and both participate in crypt regeneration.

Insulin-like growth factor 1: common mediator of multiple enterotrophic hormones and growth factors.

PURPOSE OF REVIEW: To summarize the recent evidence that insulin-like growth factor 1 (IGF1) mediates growth effects of multiple trophic factors and discuss clinical relevance. RECENT FINDINGS: Recent reviews and original reports indicate benefits of growth hormone (GH) and long-acting glucagon-like peptide 2 (GLP2) analogs in short bowel syndrome and Crohn's disease. This review highlights the evidence that biomarkers of sustained small intestinal growth or mucosal healing and evaluation of intestinal epithelial stem cell biomarkers may improve clinical measures of intestinal growth or response to trophic hormones. Compelling evidence that IGF1 mediates growth effects of GH and GLP2 on intestine or linear growth in preclinical models of resection or Crohn's disease is presented, along with a concept that these hormones or IGF1 may enhance sustained growth if given early after bowel resection. Evidence that suppressor of cytokine signaling protein induction by GH or GLP2 in normal or inflamed intestine may limit IGF1-induced growth, but protect against risk of dysplasia or fibrosis, is reviewed. Whether IGF1 receptor mediates IGF1 action and potential roles of insulin receptors are addressed. SUMMARY: IGF1 has a central role in mediating trophic hormone action in small intestine. Better understanding of benefits and risks of IGF1, receptors that mediate IGF1 action, and factors that limit undesirable growth are needed.

Themes in fibrosis and gastrointestinal inflammation.

Wound healing is an appropriate response to inflammation and tissue injury in the gastrointestinal tract. If wound healing responses are excessive, perpetuated, or prolonged, they lead to fibrosis, distortion of tissue architecture, and loss of function. This introductory editorial and the minireviews or reviews in this themes series highlight the diversity in severity and location of fibrosis in response to gastrointestinal inflammation. The multiplicity of cellular and molecular mediators and new players, including stem cells or extracellular matrix-producing cells derived from nonmesenchymal cell types, is reviewed. Comparisons of inflammation-induced fibrosis across organ systems and the need for integrated and systems-based molecular approaches, new imaging modalities, well-characterized animal models, cell culture models, and improved diagnostic or predictive markers are reviewed. To date, intestinal fibrosis has received much less attention than inflammation in terms of defining mechanisms and underlying causes. This themes series aims to illustrate the importance of research in this area in gastrointestinal health and disease.

Suppressor of cytokine signaling-2 gene disruption promotes Apc(Min/+) tumorigenesis and activator protein-1 activation.

Epigenetic in vitro and in vivo studies suggest that suppressor of cytokine signaling-2 (SOCS2) may normally limit tumorigenesis in the intestine; however, this theory has not been directly tested. We hypothesized that SOCS2 deficiency promotes spontaneous intestinal tumorigenesis in Apc(Min/+) mice. Therefore, we quantified tumor number, size, and load in the small intestine and colon using SOCS2(+/+)/Apc(Min/+), SOCS2(+/-)/Apc(Min/+), and SOCS2(-/-)/Apc(Min/+) mice and assayed hematocrit as an indirect marker of disease severity. Biochemical and histological assays were used to assess mechanisms. Heterozygous and homozygous disruption of SOCS2 alleles promoted 166 and 441% increases in tumor load in the small intestine, respectively, accelerated development of colon tumors, and caused severe anemia. SOCS2 deletion promoted significant increases in intestinal insulin-like growth factor-I mRNA but did not affect plasma insulin-like growth factor-I. Western blots and immunohistochemical analysis demonstrated that tumor and nontumor intestinal tissue of SOCS2(-/-)/Apc(Min/+) mice had increased serine 727 phosphorylation of signal transducer and activator of transcription 3 compared with SOCS2(+/+)/Apc(Min/+) mice. Moreover, electromobility shift assays showed that SOCS2 deletion did not alter signal transducer and activator of transcription 3 DNA binding. However, tumors and small intestine from SOCS2(-/-)/Apc(Min/+) showed dramatic increases in activator protein-1 (AP-1) DNA binding, and SOCS2 overexpression in vitro reduced levels of AP-1. These studies indicate that SOCS2 deletion promotes the spontaneous development of intestinal tumors driven by mutations in the adenomatous polyposis coli/beta-catenin pathway and activates AP-1. Therefore, reduced expression or epigenetic silencing of SOCS2 may serve as a useful biomarker for colorectal cancer risk.

Inflammation enhances resection-induced intestinal adaptive growth in IL-10 null mice.

BACKGROUND: Surgical resection of the ileum, cecum, and proximal right colon (ICR) is common in the management of Crohn's disease, yet little is known about the effect of active inflammation on the adaptive response following intestinal loss. We recently developed a surgical model of ICR in germ-free (GF) IL-10 null mice that develop small intestinal inflammation only when mice undergo conventionalization with normal fecal microflora (CONV) before surgical intervention. In this study, we examined the effects of postsurgical small bowel inflammation on adaptive growth after ICR. METHODS: GF 129SvEv IL-10 null mice, 8-10 wk old, were allocated to GF or CONV groups. Nonoperated GF and CONV mice provided baseline controls. Two wk later, GF and CONV mice were further allocated to ICR or sham operation. Small intestine and colon were harvested 7 d after surgery for histological analysis. RESULTS: All mice within the gnotobiotic facility maintained GF status and did not develop small intestinal or colonic inflammation. CONV resulted in colitis in all groups, whereas small intestinal inflammation was only observed following ICR. Resection-induced small intestinal inflammation in CONV mice was associated with increases in proliferation, crypt depth, and villus height compared with GF mice after ICR. Resection-induced increases in crypt fission only occurred in CONV mice. CONCLUSION: ICR-dependent small intestinal inflammation in CONV IL-10 null mice dramatically enhances early adaptive growth of the small intestine. Additional studies utilizing our model may provide clinical insight leading to optimal therapies in managing IBD patients after surgical resection.

The Impact of Individual Mentored Career Development (K) Awards on the Research Trajectories of Early-Career Scientists.

PURPOSE: This analysis examined the role of a National Institutes of Health (NIH) individual Mentored Career Development Award (K01, K08, K23) on launching and sustaining independent research careers for early-career scientists, and investigated the effects of these awards during and after the doubling of the NIH budget. METHOD: The authors used grants data from the NIH covering the period 1990 through 2016, and compared success in receipt of R01 equivalent awards (R01 Eq.) and Research Project Grants (RPGs) for K awardees and K applicants who did not receive funding. The analysis combined regression discontinuity design with coarsened exact matching, and regression. RESULTS: Overall, receipt of K award was associated with a 24.1% increase in likelihood of first independent NIH award (P < .01), and a larger number of R01 Eq. and RPG awards. After accounting for first major independent awards, K awards were uncorrelated with receiving second major independent research awards. Comparing different funding periods, K01 awards were predictive of subsequent R01 Eq. and RPG awards after but not during the NIH doubling, K08 awards were predictive only during the NIH doubling, and K23 awards were predictive during both periods. CONCLUSIONS: Receipt of Mentored Career Development Awards was linked to increased likelihood that early-career scientists successfully transitioned to an independent research career. These findings indicate that extending funding to additional K award applicants with meritorious scores could significantly strengthen the pipeline of biomedical researchers. In addition, enhancing K awards may be relevant to sustaining research careers for clinician scientists.

Insulin receptor substrate-1 deficiency promotes apoptosis in the putative intestinal crypt stem cell region, limits Apcmin/+ tumors, and regulates Sox9.

Reduced apoptosis of crypt stem/progenitor cells and elevated insulin and IGFs are linked to colon cancer risk. Insulin receptor substrate-1 (IRS-1) mediates the actions of insulin, IGF-I, and IGF-II, but the role of endogenous IRS-1 in crypt apoptosis and cancer is undefined. Using IRS-1(-/-), IRS-1(+/-), and IRS-1(+/+) mice, we tested the hypothesis that reduced IRS-1 expression increases apoptosis of intestinal crypt cells and protects against Apc(min/+) (Min)/beta-catenin-driven intestinal tumors. Expression of Sox9, a transcriptional target of Tcf/beta-catenin and putative biomarker of crypt stem cells, was assessed in intestine of different IRS-1 genotypes and cell lines. Irradiation-induced apoptosis was significantly increased in the crypts and crypt stem cell region of IRS-1-deficient mice. Tumor load was significantly reduced by 31.2 +/- 14.6% in IRS-1(+/-)/Min and by 64.1 +/- 7.6% in IRS-1(-/-)/Min mice, with more prominent reductions in tumor number than size. Compared with IRS-1(+/+)/Min, IRS-1(-/-)/Min mice had fewer Sox9-positive cells in intestinal crypts and reduced Sox9 mRNA in intestine. IRS-1 overexpression increased Sox9 expression in an intestinal epithelial cell line. We conclude that even small reductions in endogenous IRS-1 increase apoptosis of crypt stem or progenitor cells, protect against beta-catenin-driven intestinal tumors, and reduce Sox9, a Tcf/beta-catenin target and putative stem/progenitor cell biomarker.

Biochromoendoscopy: molecular imaging with capsule endoscopy for detection of adenomas of the GI tract.

BACKGROUND: Current capsule endoscopy (CE) provides minimally invasive technology for GI imaging but has limited ability to discriminate different types of polyps. Near infrared fluorescent (NIRF) probes activated by biomarkers upregulated in adenomas (eg, cathepsin B) are potentially powerful tools to distinguish premalignant or malignant lesions from benign or inflammatory lesions. OBJECTIVES: To examine whether CE can be integrated with NIRF probes to detect adenomas and whether cathepsin B-activated NIRF probes are activated by benign or inflammatory lesions. DESIGN: Mouse models of adenomas, hyperplactic/lymphoid polyps, and acute or chronic intestinal inflammation were injected intravenously with a cathepsin B-activated probe (Prosense 680). Dissected intestine was imaged with CE under white or NIRF light. For NIRF excitation (680 nm), dichroic and emission (700 nm) filters were combined with CE when images were recorded. Prosense 680 samples with or without protease were used as positive and negative controls. CE-based imaging data were verified by using and independent imaging system (Xenogen IVIS system). MAIN OUTCOME MEASUREMENTS: Proof of principal that CE integrated with NIRF probes can detect and discriminate adenomas from other lesions. RESULTS: CE-based NIRF imaging with Prosense 680 readily visualized adenomas, including in the colitis model. NIRF signals of different intensities were detected. Prosense 680 was not activated by benign or inflammatory lesions. LIMITATION: Optical filters external to the capsule were used. CONCLUSIONS: We demonstrate proof of the principle that biochromoendoscopy-CE combined with molecular probes--provides a novel approach that differentiates adenomas from benign polyps and inflammatory lesions.

Clinician-Investigator Training and the Need to Pilot New Approaches to Recruiting and Retaining This Workforce.

Clinician-investigators, also called physician-scientists, offer critical knowledge and perspectives that benefit research on basic science mechanisms, improved diagnostic and therapeutic approaches, population and outcomes medicine, health policy, and health services, yet few clinically trained health professionals pursue a research career. Sustaining this workforce requires attention to the unique challenges faced by investigators who must achieve clinical and research competence during training and their careers. These challenges include the duration of required clinical training, limited or discontinuous research opportunities, high levels of educational debt, balancing the dual obligations and rewards of clinical care and research, competition for research funding, and the need for leadership development after training. Women and individuals from underrepresented racial and ethnic groups comprise a small percentage of this workforce.The authors summarize the recent literature on training for clinician-investigators, emphasizing approaches with encouraging outcomes that warrant broader implementation. Using this overview as background, they convened three workshops at the National Institutes of Health in 2016 to identify and refine key priorities for potential new pilot programs to recruit and retain the clinician-investigator workforce. From these workshops emerged three priorities for future pilot programs: (1) support for research in residency, (2) new research on-ramps for health professionals at multiple career stages, and (3) national networks to diversify and sustain clinician-investigator faculty. Implementation of any pilot program will require coordinated commitment from academic health centers, medical licensing/certification boards, professional societies, and clinician-investigators themselves, in addition to support from the National Institutes of Health.

Women's Careers in Biomedical Sciences: Implications for the Economy, Scientific Discovery, and Women's Health.

While women have been well represented in medical school and biomedical doctoral degree programs, they do not comprise half of academic medicine faculty positions. Furthermore, there is a significant paucity of women in academic medicine leadership positions, as evidenced by the fact that only 16% of dean positions at United States Medical schools are filled by women. In this commentary, the authors review the state of women in academic medicine and argue that increased representation of women in the academic workforce will lead to economic gains, increased scientific discovery, and improvements to women's health.

Orphan Gpr182 suppresses ERK-mediated intestinal proliferation during regeneration and adenoma formation.

Orphan GPCRs provide an opportunity to identify potential pharmacological targets, yet their expression patterns and physiological functions remain challenging to elucidate. Here, we have used a genetically engineered knockin reporter mouse to map the expression pattern of the Gpr182 during development and adulthood. We observed that Gpr182 is expressed at the crypt base throughout the small intestine, where it is enriched in crypt base columnar stem cells, one of the most active stem cell populations in the body. Gpr182 knockdown had no effect on homeostatic intestinal proliferation in vivo, but led to marked increases in proliferation during intestinal regeneration following irradiation-induced injury. In the ApcMin mouse model, which forms spontaneous intestinal adenomas, reductions in Gpr182 led to more adenomas and decreased survival. Loss of Gpr182 enhanced organoid growth efficiency ex vivo in an EGF-dependent manner. Gpr182 reduction led to increased activation of ERK1/2 in basal and challenge models, demonstrating a potential role for this orphan GPCR in regulating the proliferative capacity of the intestine. Importantly, GPR182 expression was profoundly reduced in numerous human carcinomas, including colon adenocarcinoma. Together, these results implicate Gpr182 as a negative regulator of intestinal MAPK signaling-induced proliferation, particularly during regeneration and adenoma formation.