Microbiota of Inflammatory Bowel Disease Models

Gut microbiome plays an important role in inflammatory bowel disease (IBD), a group of intestinal chronic inflammation conditions that affect a large population. The animal models of IBD have long been established on basis of pathological features, but their ability to recapitulate patient gut microbiota is unknown. We investigated and compared the composition and biodiversity of bacterial population in the fecal samples from rat models of the two IBD subtypes, and compared them with patient samples. Our analyses revealed that inflammation reduces overall microbiome diversity and increased variation between individuals. We identified specific microbial signatures associated with the two IBD subtypes that were consistent between the animal models and human IBD patients, suggesting that the animal models can partially recapitulate the microbiota in human diseases. Furthermore, metagenome prediction analysis suggested microbial functions that were likely altered by host-microbiota interactions in IBD models.

Single-Cell Transcriptomics Reveals Heterogeneity and Drug Response of Human Colorectal Cancer Organoids

Organoids are three-dimensional cell cultures that mimic organ functions and structures. The organoid model has been developed as a versatile in vitro platform for stem cell biology and diseases modeling. Tumor organoids are shown to share ~ 90% of genetic mutations with biopsies from same patients. However, it's not clear whether tumor organoids recapitulate the cellular heterogeneity observed in patient tumors. Here, we used single-cell RNA-Seq to investigate the transcriptomics of tumor organoids derived from human colorectal tumors, and applied machine learning methods to unbiasedly cluster subtypes in tumor organoids. Computational analysis reveals cancer heterogeneity sustained in tumor organoids, and the subtypes in organoids displayed high diversity. Furthermore, we treated the tumor organoids with a first-line cancer drug, Oxaliplatin, and investigated drug response in single-cell scale. Diversity of tumor cell populations in organoids were significantly perturbed by drug treatment. Single-cell analysis detected the depletion of chemosensitive subgroups and emergence of new drug tolerant subgroups after drug treatment. Our study suggests that the organoid model is capable of recapitulating clinical heterogeneity and its evolution in response to chemotherapy.

Effects of acarbose and siglitine on blood glucose fluctuation and islet β-cell function in patients with type 2 diabetes mellitus

The effects of acarbose and sitagliptin on blood glucose fluctuation and islet β-cell function in patients with type 2 diabetes mellitus (T2DM) were studied. One hundred and three patients with poorly controlled T2DM with insulin aspart 30 were selected and randomly divided into three groups: group A [continuous subcutaneous insulin infusion (CSII) treatment group], group B (CSII combined with acarbose treatment), group C (CSII combined with sitagliptin treatment). The treatment lasted for two weeks and the clinical indicators in the three groups were measured. The insulin dosage was adjusted according to the blood glucose statuses of the three groups of patients. In the final three days, 72 h of continuous glucose monitoring (CGM) were carried out, and the OGTT test was performed again. The results showed that the MODD (absolute means of daily difference), intra-day blood glucose fluctuation indices [(24 h MBG (mean blood glucose), LAGE (largest amplitude of glycemic excursions) and MAGE (average blood glucose fluctuation)] and postprandial blood glucose fluctuation indices [PGS (postprandial glucose spike), △t, PPGE (postprandial glucose excursion) and T (time) total] in group C and group B were significantly lower than those in group A. Compared with group B, the difference in blood glucose fluctuation indices in group C was not statistically significant (P>0.05). The HOMA-islet (homeostasis model assessment of islet) (CP-DM) index and FC-P (Fasting c-peptide) levels in group C and group B were significantly higher than those in group A (P less than 0.01). The HOMA-IR (CP) index of groups B and C was significantly lower than that of group A (P less than 0.01), and there was no statistically significant difference between groups B and C (P less than 0.05). Sitagliptin combined with intensive insulin pump therapy can reduce blood glucose fluctuation throughout the day, reduce insulin dosage, improve islet B cell function and reduce hypoglycemia better than intensive insulin pump therapy alone.

miR-34a is a microRNA safeguard for Citrobacter-induced inflammatory colon oncogenesis

Inflammation often induces regeneration to repair the tissue damage. However, chronic inflammation can transform temporary hyperplasia into a fertile ground for tumorigenesis. Here, we demonstrate that the microRNA miR-34a acts as a central safeguard to protect the inflammatory stem cell niche and reparative regeneration. Although playing little role in regular homeostasis, miR-34a deficiency leads to colon tumorigenesis after Citrobacter rodentium infection. miR-34a targets both immune and epithelial cells to restrain inflammation-induced stem cell proliferation. miR-34a targets Interleukin six receptor (IL-6R) and Interleukin 23 receptor (IL-23R) to suppress T helper 17 (Th17) cell differentiation and expansion, targets chemokine CCL22 to hinder Th17 cell recruitment to the colon epithelium, and targets an orphan receptor Interleukin 17 receptor D (IL-17RD) to inhibit IL-17-induced stem cell proliferation. Our study highlights the importance of microRNAs in protecting the stem cell niche during inflammation despite their lack of function in regular tissue homeostasis.

[Spatial-temporal distribution characteristics of hepatitis E in Shanghai, 2006-2016]

Objective: To understand the epidemiologic characteristics and spatial-temporal distribution of hepatitis E in Shanghai between 2006 and 2016. Methods: The reported incidence of hepatitis E and health facilities' information between 2006 and 2016 were collected from the China Information System for Disease Control and Prevention. The geographic information were from Shanghai Surveying and Mapping Institute. The map scale was 1∶750 000. Global and local autocorrelation, and spatial-temporal detection methods were applied to determine the spatial-temporal characteristics of hepatitis E. Software ArcGIS 10.1 was used to analyze global and local spatial auto correlation of hepatitis E spatial clusters. Software SaTScan 9.4.4 was used to conduct scan for exploring the areas of hepatitis E temporal spatial clusters. Results: A total of 6 048 cases of hepatitis E were reported in Shanghai during 2006-2016. The average incidence was 2.14/100 000. Spatial auto correlation analysis indicated that there was significant spatial positive correlations and spatial-temporal clustering of hepatitis E in Shanghai, and the "high-high cluster" was mainly located in the downtown of the city. Conclusion: Understanding the spatial-temporal clustering areas of hepatitis E cases in Shanghai from 2006 to 2016 is important to the reasonable allocation of public health resources and effective prevention and control of hepatitis E.

Aldolase B-Mediated Fructose Metabolism Drives Metabolic Reprogramming of Colon Cancer Liver Metastasis

Cancer metastasis accounts for the majority of cancer-related deaths and remains a clinical challenge. Metastatic cancer cells generally resemble cells of the primary cancer, but they may be influenced by the milieu of the organs they colonize. Here, we show that colorectal cancer cells undergo metabolic reprogramming after they metastasize and colonize the liver, a key metabolic organ. In particular, via GATA6, metastatic cells in the liver upregulate the enzyme aldolase B (ALDOB), which enhances fructose metabolism and provides fuel for major pathways of central carbon metabolism during tumor cell proliferation. Targeting ALDOB or reducing dietary fructose significantly reduces liver metastatic growth but has little effect on the primary tumor. Our findings suggest that metastatic cells can take advantage of reprogrammed metabolism in their new microenvironment, especially in a metabolically active organ such as the liver. Manipulation of involved pathways may affect the course of metastatic growth.

Prometheus revisited

The liver's extraordinary ability to regenerate has been known since the myth of Prometheus, but the mechanisms involved are still being discovered. Various small animal models have been used in this quest. Two of the most popular include partial hepatectomy (PHx), in which two-thirds of the liver mass is surgically removed to evoke a massive, immediate stimulus for regeneration, and prolonged exposure to toxins that kill liver cells more gradually, provoking chronic regenerative activity. In either case, multiple types of cells must interact effectively to repopulate the organ with functional mature hepatocytes and thus assure ultimate restoration of healthy liver structure and function. This complexity has confounded efforts to distinguish specific changes that occur in cells that repopulate the hepatocyte compartment from changes in other cell populations, including subpopulations of hepatocytes or hepatocyte precursors that do not become regenerative. In the current issue of the JCI, Wang et al. used translating ribosome affinity purification followed by high-throughput RNA sequencing (TRAP-seq) to isolate mRNAs from repopulating hepatocytes in order to profile gene expression specifically in the hepatocytes that regenerate the liver following toxic injury imposed by inherent byproducts of tyrosine metabolism. This innovative methodology can potentially be used to design therapeutic strategies for liver regeneration.

[Impact on the incidence of postoperative ventricular arrhythmias after cardiac resynchronization therapy defibrillator with quadripolar lead]

Objective: To evaluate incidence of postoperative ventricular arrhythmias in patients who received cardiac resynchronization therapy defibrillator (CRT-D ) with left ventricular quadripolar lead. Methods: The patients received CRT-D who had complete follow-up data in Anhui Provincial Hospital from June 2013 to June 2016 were included and divided into quadripolar lead group and bipolar lead group according to the type of left ventricular lead. And ventricular arrhythmia (VA), implantable cardioverter-defibrillator (ICD) shocks treatment, antitachycardia pacing therapy (ATP), and other indicators of the two groups were compared. Prognosis of the two groups was assessed by re-hospitalization for heart failure and cardiac death. Results: Of the 220 patients enrolled in the study, 58 patients were in quadripolar lead group and 162 in bipolar lead group, and there were no significant differences in baseline characteristics between the two groups. The VA episode per patient was not significantly different between the two groups [(0.60±2.38) VA per person vs (0.93±2.24) VA per person, P=0.055]; the quadripolar lead group had significantly lower burden of VA compared with bipolar lead group [(0.22±0.91) per person-year vs (0.46±1.13) per person-year, P=0.044]. Compared with bipolar lead group, there were significant reduction in both the ICD shocks per patient and the burden of ICD shocks in quadripolar lead group: [(0.12±0.36) shocks per person vs (0.23±0.52) shocks per person, P=0.034] and [(0.04±0.17) per person-year vs (0.12±0.46) per person-year, P=0.029], respectively. There were no significant differences between the two groups in both the ATP per patient and the burden of ATP: [(1.07±3.77) ATP per person vs (1.26±3.01) ATP per person, P=0.073] and [(0.38±1.39) per person-year vs (0.63±1.48) per person-year, P=0.058], respectively. And there were no significant differences between the two groups for the survival (P=0.496). Conclusion: Compared with bipolar lead group, the burden of VA could be significantly reduced after CRT-D in the quadripolar lead group.

A Notch positive feedback in the intestinal stem cell niche is essential for stem cell self-renewal

The intestinal epithelium is the fastest regenerative tissue in the body, fueled by fast-cycling stem cells. The number and identity of these dividing and migrating stem cells are maintained by a mosaic pattern at the base of the crypt. How the underlying regulatory scheme manages this dynamic stem cell niche is not entirely clear. We stimulated intestinal organoids with Notch ligands and inhibitors and discovered that intestinal stem cells employ a positive feedback mechanism via direct Notch binding to the second intron of the Notch1 gene. Inactivation of the positive feedback by CRISPR/Cas9 mutation of the binding sequence alters the mosaic stem cell niche pattern and hinders regeneration in organoids. Dynamical system analysis and agent-based multiscale stochastic modeling suggest that the positive feedback enhances the robustness of Notch-mediated niche patterning. This study highlights the importance of feedback mechanisms in spatiotemporal control of the stem cell niche.

Fucosylation Deficiency in Mice Leads to Colitis and Adenocarcinoma

BACKGROUND & AIMS

De novo synthesis of guanosine diphosphate (GDP)-fucose, a substrate for fucosylglycans, requires sequential reactions mediated by GDP-mannose 4,6-dehydratase (GMDS) and GDP-4-keto-6-deoxymannose 3,5-epimerase-4-reductase (FX or tissue specific transplantation antigen P35B [TSTA3]). GMDS deletions and mutations are found in 6%-13% of colorectal cancers; these mostly affect the ascending and transverse colon. We investigated whether a lack of fucosylation consequent to loss of GDP-fucose synthesis contributes to colon carcinogenesis.

METHODS

FX deficiency and GMDS deletion produce the same biochemical phenotype of GDP-fucose deficiency. We studied a mouse model of fucosylation deficiency (Fx-/- mice) and mice with the full-length Fx gene (controls). Mice were placed on standard chow or fucose-containing diet (equivalent to a control fucosylglycan phenotype). Colon tissues were collected and analyzed histologically or by enzyme-linked immunosorbent assays to measure cytokine levels; T cells also were collected and analyzed. Fecal samples were analyzed by 16s ribosomal RNA sequencing. Mucosal barrier function was measured by uptake of fluorescent dextran. We transplanted bone marrow cells from Fx-/- or control mice (Ly5.2) into irradiated 8-week-old Fx-/- or control mice (Ly5.1). We performed immunohistochemical analyses for expression of Notch and the hes family bHLH transcription factor (HES1) in colon tissues from mice and a panel of 60 human colorectal cancer specimens (27 left-sided, 33 right-sided).

RESULTS

Fx-/- mice developed colitis and serrated-like lesions. The intestinal pathology of Fx-/- mice was reversed by addition of fucose to the diet, which restored fucosylation via a salvage pathway. In the absence of fucosylation, dysplasia appeared and progressed to adenocarcinoma in up to 40% of mice, affecting mainly the right colon and cecum. Notch was not activated in Fx-/- mice fed standard chow, leading to decreased expression of its target Hes1. Fucosylation deficiency altered the composition of the fecal microbiota, reduced mucosal barrier function, and altered epithelial proliferation marked by Ki67. Fx-/- mice receiving control bone marrow cells had intestinal inflammation and dysplasia, and reduced expression of cytokines produced by cytotoxic T cells. Human sessile serrated adenomas and right-sided colorectal tumors with epigenetic loss of MutL homolog 1 (MLH1) had lost or had lower levels of HES1 than other colorectal tumor types or nontumor tissues.

CONCLUSIONS

In mice, fucosylation deficiency leads to colitis and adenocarcinoma, loss of Notch activation, and down-regulation of Hes1. HES1 loss correlates with the development of human right-sided colorectal tumors with epigenetic loss of MLH1. These findings indicate that carcinogenesis in a subset of colon cancer is consequent to a molecular mechanism driven by fucosylation deficiency and/or HES1-loss.

A miR-34a-Numb Feedforward Loop Triggered by Inflammation Regulates Asymmetric Stem Cell Division in Intestine and Colon Cancer

Emerging evidence suggests that microRNAs can initiate asymmetric division, but whether microRNA and protein cell fate determinants coordinate with each other remains unclear. Here, we show that miR-34a directly suppresses Numb in early-stage colon cancer stem cells (CCSCs), forming an incoherent feedforward loop (IFFL) targeting Notch to separate stem and non-stem cell fates robustly. Perturbation of the IFFL leads to a new intermediate cell population with plastic and ambiguous identity. Lgr5+ mouse intestinal/colon stem cells (ISCs) predominantly undergo symmetric division but turn on asymmetric division to curb the number of ISCs when proinflammatory response causes excessive proliferation. Deletion of miR-34a inhibits asymmetric division and exacerbates Lgr5+ ISC proliferation under such stress. Collectively, our data indicate that microRNA and protein cell fate determinants coordinate to enhance robustness of cell fate decision, and they provide a safeguard mechanism against stem cell proliferation induced by inflammation or oncogenic mutation.

Daily physical activity patterns from hip- and wrist-worn accelerometers

Accelerometer wear location may influence physical activity estimates. This study investigates this relationship through the examination of activity patterns throughout the day. Participants from the aging research evaluating accelerometry (AREA) study (n men  =  37, n women  =  47, mean age (SD)  =  78.9 (5.5) years) were asked to wear accelerometers in a free-living environment for 7 d at three different wear locations; one on each wrist and one on the right hip. During waking hours, wrist-worn accelerometers consistently produced higher median activity counts, about 5  ×  higher, as well as wider variability compared to hip-worn monitors. However, the shape of the accrual pattern curve over the course of the day for the hip and wrist are similar; there is a spike in activity in the morning, with a prolonged tapering of activity level as the day progresses. The similar patterns of hip and wrist activity accrual provide support that each location is capable of estimating total physical activity volume. The examination of activity patterns over time may provide a more detailed way to examine differences in wear location and different subpopulations.

Notch signalling regulates asymmetric division and inter-conversion between lgr5 and bmi1 expressing intestinal stem cells

Rapidly cycling LGR5+ intestinal stem cells (ISCs) located at the base of crypts are the primary driver of regeneration. Additionally, BMI1 expression is correlated with a slow cycling pool of ISCs located at +4 position. While previous reports have shown interconversion between these two populations following tissue injury, we provide evidence that NOTCH signaling regulates the balance between these two populations and promotes asymmetric division as a mechanism for interconversion in the mouse intestine. In both in vitro and in vivo models, NOTCH suppression reduces the ratio of BMI1+/LGR5+ ISCs while NOTCH stimulation increases this ratio. Furthermore, NOTCH signaling can activate asymmetric division after intestinal inflammation. Overall, these data provide insights into ISC plasticity, demonstrating a direct interconversion mechanism between slow- and fast-cycling ISCs.

NOTCH Signaling Regulates Asymmetric Cell Fate of Fast- and Slow-Cycling Colon Cancer-Initiating Cells

Colorectal cancer cells with stem-like properties, referred to as colon cancer-initiating cells (CCIC), have high tumorigenic potential. While CCIC can differentiate to promote cellular heterogeneity, it remains unclear whether CCIC within a tumor contain distinct subpopulations. Here, we describe the co-existence of fast- and slow-cycling CCIC, which can undergo asymmetric division to generate each other, highlighting CCIC plasticity and interconvertibility. Fast-cycling CCIC express markers, such as LGR5 and CD133, rely on MYC for their proliferation, whereas slow-cycling CCIC express markers, such as BMI1 and hTERT, are independent of MYC. NOTCH signaling promotes asymmetric cell fate, regulating the balance between these two populations. Overall, our results illuminate the basis for CCIC heterogeneity and plasticity by defining a direct interconversion mechanism between slow- and fast-cycling CCIC. Cancer Res; 76(11); 3411-21. ©2016 AACR.

Protective effect of penehyclidine hydrochloride on lipopolysaccharide-induced acute kidney injury in rat

We aimed to observe the effect of penehyclidine hydrochloride (PHC) on lipopolysaccharide (LPS)-induced acute kidney injury in rats and expression of tight junction proteins ZO-1 and occludin. Adult male Sprague-Dawley (SD) rats were divided randomly (N = 10) into control group (C), LPS group (LPS), low-dose PHC group (L-PHC), and high-dose PHC group (H-PHC). All rats, except C group, received a vena caudalis injection of 5.0 mg/kg LPS; after 30 min, rats in L-PHC and H-PHC groups received a vena caudalis injection of 0.3 and 0.9 mg/kg PHC. After 24 h, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, serum creatinine (Scr), and blood urea nitrogen (BUN) were detected. Histopathological changes and expression of ZO-1 and occludin were observed in renal tissues. Versus levels of TNF-α (38.5 ± 9.0), IL-1β (46.3 ± 12.7), Scr (37.2 ± 9.3), and BUN (6.5 ± 1.1) in control group, those in LPS group, TNF-α (159.0 ± 21.3), IL-1β (130.8 ± 18.7), Scr (98.5 ± 18.2), and BUN (12.8 ± 1.8), increased obviously (P < 0.05), with significantly structural changes and decreases of ZO-1 and occludin. However, TNF-α (111.3 ± 11.6), IL-1β (78.4 ± 14.3), Scr (51.3 ± 12.5), BUN (8.1 ± 1.2) in H-PHC group, and TNF-α (120.8 ± 14.3), IL-1β (92.5 ± 19.0), Scr (56.7 ± 14.7), BUN (9.7 ± 1.6) in L-PHC group were obviously decreased (P < 0.05). PHC has protective effects on acute kidney injury in sepsis, including abatement of renal tissue inflammation and functional improvement, potentially by upregulating ZO-1 and occludin.

miR-1269 promotes metastasis and forms a positive feedback loop with TGF-β

As patient survival drops precipitously from early-stage cancers to late-stage and metastatic cancers, microRNAs that promote relapse and metastasis can serve as prognostic and predictive markers as well as therapeutic targets for chemoprevention. Here we show that miR-1269a promotes colorectal cancer (CRC) metastasis and forms a positive feedback loop with TGF-β signalling. miR-1269a is upregulated in late-stage CRCs, and long-term monitoring of 100 stage II CRC patients revealed that miR-1269a expression in their surgically removed primary tumours is strongly associated with risk of CRC relapse and metastasis. Consistent with clinical observations, miR-1269a significantly increases the ability of CRC cells to invade and metastasize in vivo. TGF-β activates miR-1269 via Sox4, while miR-1269a enhances TGF-β signalling by targeting Smad7 and HOXD10, hence forming a positive feedback loop. Our findings suggest that miR-1269a is a potential marker to inform adjuvant chemotherapy decisions for CRC patients and a potential therapeutic target to deter metastasis.

A bio-inspired spatial patterning circuit

Lateral Inhibition (LI) is a widely conserved patterning mechanism in biological systems across species. Distinct from better-known Turing patterns, LI depend on cell-cell contact rather than diffusion. We built an in silico genetic circuit model to analyze the dynamic properties of LI. The model revealed that LI amplifies differences between neighboring cells to push them into opposite states, hence forming stable 2-D patterns. Inspired by this insight, we designed and implemented an electronic circuit that recapitulates LI patterning dynamics. This biomimetic system serve as a physical model to elucidate the design principle of generating robust patterning through spatial feedback, regardless of the underlying devices being biological or electrical.

Coexistence of neurofibroma and meningioma at exactly the same level of the cervical spine

We report a case of the coexistence of different spinal tumors at the same level of the cervical spine, without neurofibromatosis (NF), which was successfully treated with surgery. A 72-year-old female presented with right upper-limb clumsiness and weakness. Magnetic resonance imaging revealed an intradural, extramedullary tumor mass at the right C3-4 level with extradural extension into the intervertebral foramen. The extradural tumor was removed, and the pathology showed neurofibroma. After incision of the dura, the intradural tumor was removed, and was identified as meningioma in the pathological report. The patient did not meet the criteria of NF. Coexistence of neurofibroma and meningioma at exactly the same level of the spine without NF is extremely rare. Exploration of the intradural space may be necessary after resection of an extradural tumor if the surgical finding does not correlate well with the preoperative images.

A metabolic signature of colon cancer initiating cells

Colon cancer initiating cells (CCICs) are more tumorigenic and metastatic than the majority of colorectal cancer (CRC) cells. CCICs have also been associated with stem cell-like properties. However, there is a lack of system-level understanding of what mechanisms distinguish CCICs from common CRC cells. We compared the transcriptomes of CD133+ CCICs and CD133- CRC cells from multiple sources, which identified a distinct metabolic signature for CD133(high) CCICs. High-resolution unbiased metabolomics was then performed to validate this CCIC metabolic signature. Specifically, levels of enzymes and metabolites involved in glycolysis, the citric acid (TCA) cycle, and cysteine and methionine metabolism are altered in CCICs. Analyses of the alterations further suggest an epigenetic link. This metabolic signature provides mechanistic insights into CCIC phenotypes and may serve as potential biomarkers and therapeutic targets for future CRC treatment.

Randomized trial of nutrition education added to internet-based information and exercise at the work place for weight loss in a racially diverse population of overweight women

OBJECTIVE

Obesity in the United States is highly prevalent, approaching 60% for black women. We investigated whether nutrition education sessions at the work place added to internet-based wellness information and exercise resources would facilitate weight and fat mass loss in a racially diverse population of overweight female employees.

METHODS

A total of 199 (average body mass index 33.9±6.3 kg m(-2)) nondiabetic women (57% black) at our institution were randomized to a 6-month program of either internet-based wellness information (WI) combined with dietitian-led nutrition education group sessions (GS) weekly for 3 months and then monthly with shift in emphasis to weight loss maintenance (n=99) or to WI alone (n=100). All were given access to exercise rooms convenient to their work site. Fat mass was measured by dual-energy X-ray absorptiometry.

RESULTS

WI+GS subjects lost more weight than WI subjects at 3 months (-2.2±2.8 vs -1.0±3.0 kg, P>0.001). Weight (-2.7±3.9 vs -2.0±3.9 kg) and fat mass (-2.2±3.1 vs -1.7±3.7 kg) loss at 6 months was significant for WI+GS and WI groups (both P<0.001), but without significant difference between groups (both P>0.10); 27% of the WI+GS group achieved 5% loss of initial weight as did 18% of the WI group (P=0.180). Blacks and whites similarly completed the study (67 vs 74%, P=0.303), lost weight (-1.8±3.4 vs -3.3±5.2 kg, P=0.255) and fat mass (-1.6±2.7 vs -2.5±4.3 kg, P=0.532), and achieved 5% loss of initial weight (21 vs 32%, P=0.189), irrespective of group assignment.

CONCLUSION

Overweight women provided with internet-based wellness information and exercise resources at the work site lost weight and fat mass, with similar achievement by black and white women. Additional weight loss benefit of nutrition education sessions, apparent at 3 months, was lost by 6 months and may require special emphasis on subjects who fail to achieve weight loss goals to show continued value.

Fibroblast growth factor 21 (FGF21) and bone: is there a relationship in humans?

In animals, high fibroblast growth factor 21 (FGF21) states improve insulin resistance but induce bone loss. Whether FGF21 relates to bone mineral density (BMD) is unknown in humans. Contrary to prediction from animal findings, we found higher FGF21 levels associating with greater BMD in women, independent of age and body composition.

INTRODUCTION

Recent laboratory studies suggest that FGF21 is involved in reciprocal regulation of bone and energy homeostasis. Systemic administration of FGF21 protects animals from obesity and diabetes but causes severe bone loss, smothering the enthusiasm over FGF21 as a potential antiobesity therapeutic. To date, there is no information on whether FGF21 relates to BMD in humans. We thus studied the relationship between plasma FGF21 levels and BMD in healthy adults.

METHODS

Fasting plasma FGF21 levels were measured by enzyme-linked immunosorbent assay and body composition by dual-energy X-ray absorptiometry.

RESULTS

Among 40 healthy volunteers (age 32 ± 10 year, 16 women), men had significantly higher lean body mass (p < 0.01) and total BMD (p < 0.05), and lower percent body fat than women (p < 0.01). Median plasma FGF21 levels were not different between the sexes. While there was no association between FGF21 concentrations and body composition in men, FGF21 levels correlated positively with fat mass (p < 0.01) in women. In men, no significant correlation between FGF21 with BMD was observed. However, in women, FGF21 correlated positively with total BMD (R (2) = 0.69, p = 0.003) and spine BMD (R (2) = 0.76, p = 0.001); the correlation remained significant after adjusting for age, ethnicity, and body composition.

CONCLUSIONS

This study reveals for the first time a strong positive association between plasma FGF21 levels and BMD in healthy women, suggesting the association between bone loss and high FGF21 states in animals may not be directly translated to humans in physiologic states. We hypothesize that FGF21 may increase bone mass particularly in women through paracrine mechanisms in the bone-adipose interface.