Propagation of adipogenic signals through an epigenomic transition state.

The transcriptional mechanisms by which temporary exposure to developmental signals instigates adipocyte differentiation are unknown. During early adipogenesis, we find transient enrichment of the glucocorticoid receptor (GR), CCAAT/enhancer-binding protein beta (CEBPbeta), p300, mediator subunit 1, and histone H3 acetylation near genes involved in cell proliferation, development, and differentiation, including the gene encoding the master regulator of adipocyte differentiation, peroxisome proliferator-activated receptor gamma2 (PPARgamma2). Occupancy and enhancer function are triggered by adipogenic signals, and diminish upon their removal. GR, which is important for adipogenesis but need not be active in the mature adipocyte, functions transiently with other enhancer proteins to propagate a new program of gene expression that includes induction of PPARgamma2, thereby providing a memory of the earlier adipogenic signal. Thus, the conversion of preadipocyte to adipocyte involves the formation of an epigenomic transition state that is not observed in cells at the beginning or end of the differentiation process.

Opposing effects of Apoe/Apoa1 double deletion on amyloid-ß pathology and cognitive performance in APP mice.

UNLABELLED: ATP binding cassette transporter A1 (encoded by ABCA1) regulates cholesterol efflux from cells to apolipoproteins A-I and E (ApoA-I and APOE; encoded by APOA1 and APOE, respectively) and the generation of high density lipoproteins. In Abca1 knockout mice (Abca1(ko)), high density lipoproteins and ApoA-I are virtually lacking, and total APOE and APOE-containing lipoproteins in brain substantially decreased. As the ε4 allele of APOE is the major genetic risk factor for late-onset Alzheimer's disease, ABCA1 role as a modifier of APOE lipidation is of significance for this disease. Reportedly, Abca1 deficiency in mice expressing human APP accelerates amyloid deposition and behaviour deficits. We used APP/PS1dE9 mice crossed to Apoe and Apoa1 knockout mice to generate Apoe/Apoa1 double-knockout mice. We hypothesized that Apoe/Apoa1 double-knockout mice would mimic the phenotype of APP/Abca1(ko) mice in regards to amyloid plaques and cognitive deficits. Amyloid pathology, peripheral lipoprotein metabolism, cognitive deficits and dendritic morphology of Apoe/Apoa1 double-knockout mice were compared to APP/Abca1(ko), APP/PS1dE9, and single Apoa1 and Apoe knockouts. Contrary to our prediction, the results demonstrate that double deletion of Apoe and Apoa1 ameliorated the amyloid pathology, including amyloid plaques and soluble amyloid. In double knockout mice we show that (125)I-amyloid-ß microinjected into the central nervous system cleared at a rate twice faster compared to Abca1 knockout mice. We tested the effect of Apoe, Apoa1 or Abca1 deficiency on spreading of exogenous amyloid-ß seeds injected into the brain of young pre-depositing APP mice. The results show that lack of Abca1 augments dissemination of exogenous amyloid significantly more than the lack of Apoe. In the periphery, Apoe/Apoa1 double-knockout mice exhibited substantial atherosclerosis and very high levels of low density lipoproteins compared to APP/PS1dE9 and APP/Abca1(ko). Plasma level of amyloid-ß42 measured at several time points for each mouse was significantly higher in Apoe/Apoa1 double-knockout then in APP/Abca1(ko) mice. This result demonstrates that mice with the lowest level of plasma lipoproteins, APP/Abca1(ko), have the lowest level of peripheral amyloid-ß. Unexpectedly, and independent of amyloid pathology, the deletion of both apolipoproteins worsened behaviour deficits of double knockout mice and their performance was undistinguishable from those of Abca1 knockout mice. Finally we observed that the dendritic complexity in the CA1 region of hippocampus but not in CA2 is significantly impaired by Apoe/Apoa1 double deletion as well as by lack of ABCA1. IN CONCLUSION: (i) plasma lipoproteins may affect amyloid-ß clearance from the brain by the 'peripheral sink' mechanism; and (ii) deficiency of brain APOE-containing lipoproteins is of significance for dendritic complexity and cognition.

Simple Real-Time PCR and Amplicon Sequencing Method for Identification of Plasmodium Species in Human Whole Blood.

Malaria is the leading identifiable cause of fever in returning travelers. Accurate Plasmodium species identification has therapy implications for P. vivax and P. ovale, which have dormant liver stages requiring primaquine. Compared to microscopy, nucleic acid tests have improved specificity for species identification and higher sensitivity for mixed infections. Here, we describe a SYBR green-based real-time PCR assay for Plasmodium species identification from whole blood, which uses a panel of reactions to detect species-specific non-18S rRNA gene targets. A pan-Plasmodium 18S rRNA target is also amplified to allow species identification or confirmation by sequencing if necessary. An evaluation of assay accuracy, performed on 76 clinical samples (56 positives using thin smear microscopy as the reference method and 20 negatives), demonstrated clinical sensitivities of 95.2% for P. falciparum (20/21 positives detected) and 100% for the Plasmodium genus (52/52), P. vivax (20/20), P. ovale (9/9), and P. malariae (6/6). The sensitivity of the P. knowlesi-specific PCR was evaluated using spiked whole blood samples (100% [10/10 detected]). The specificities of the real-time PCR primers were 94.2% for P. vivax (49/52) and 100% for P. falciparum (51/51), P. ovale (62/62), P. malariae (69/69), and P. knowlesi (52/52). Thirty-three specimens were used to test species identification by sequencing the pan-Plasmodium 18S rRNA PCR product, with correct identification in all cases. The real-time PCR assay also identified two samples with mixed P. falciparum and P. ovale infection, which was confirmed by sequencing. The assay described here can be integrated into a malaria testing algorithm in low-prevalence areas, allowing definitive Plasmodium species identification shortly after malaria diagnosis by microscopy.

Molecular Testing for Plasmodium falciparum by Use of Serum or Plasma and Comparison with Microscopy and Rapid Diagnostic Testing in Febrile Nigerian Patients.

Plasmodium nucleic acids have been detected in serum and plasma, but there is little published data describing the diagnostic performance of malaria nucleic acid amplification tests (NAATs) using these specimen types. Previously, our group described a multiplex NAAT for the detection of dengue virus, Leptospira, and Plasmodium species with a callout for P. falciparum (the DLM assay) that demonstrated sensitive detection of P. falciparum from plasma samples during initial evaluation. In this study, we evaluated the sensitivity and specificity of P. falciparum detection in febrile Nigerian patients using the DLM assay, microscopy, and a rapid diagnostic test (BinaxNOW Malaria). Assay performances were compared using a composite reference, which was considered positive if malaria was detected by two or more methods. Serum (n = 182) or plasma (n = 148) from 317 patients was tested; the average sample volume was 70 µl (range, 5 to 300 µl). The sensitivity and specificity of the DLM assay were 97.1% and 93.5%, respectively. The sensitivity of the malaria rapid diagnostic test (98.1%) was similar to that of the DLM assay, and both proved significantly more sensitive than microscopy (79%; P < 0.0001). When analysis was limited to samples with ≥75 µl of serum or plasma, the sensitivity of the DLM assay improved to 99% and specificity was 97.5%. For P. falciparum cases, cycle threshold values in the DLM assay correlated with the parasite density detected by microscopy (Spearman's rank correlation coefficient, P < 0.0001). In conclusion, malaria detection using the DLM assay on serum or plasma is more sensitive than and equal in specificity to microscopy in patients with P. falciparum malaria.

Genome-wide approaches reveal EGR1-controlled regulatory networks associated with neurodegeneration.

Early growth response gene 1 (Egr1) is a member of the immediate early gene (IEG) family of transcription factors and plays a role in memory formation. To identify EGR1 target genes in brain of Alzheimer's disease (AD) model mice - APP23, we applied chromatin immunoprecipitation (ChIP) followed by high-throughput DNA sequencing (ChIP-seq). Functional annotation of genes associated with EGR1 binding revealed a set of related networks including synaptic vesicle transport, clathrin-mediated endocytosis (CME), intracellular membrane fusion and transmission of signals elicited by Ca(2+) influx. EGR1 binding is associated with significant enrichment of activating chromatin marks and appears enriched near genes that are up-regulated in the brains of APP23 mice. Among the putative EGR1 targets identified and validated in this study are genes related to synaptic plasticity and transport of proteins, such as Arc, Grin1, Syn2, Vamp2 and Stx6, and genes implicated in AD such as Picalm, Psen2 and App. We also demonstrate a potential regulatory link between EGR1 and its newly identified targets in vivo, since conditions that up-regulate Egr1 levels in brain, such as a spatial memory test, also lead to increased expression of the targets. On the other hand, protein levels of EGR1 and ARC, SYN2, STX6 and PICALM are significantly lower in the brain of adult APP mice than in age-matched wild type animals. The results of this study suggest that EGR1 regulates the expression of genes involved in CME, vesicular transport and synaptic transmission that may be critical for AD pathogenesis.

Improved detection of emerging drug-resistant mutant cytomegalovirus subpopulations by deep sequencing.

In immunosuppressed hosts, the development of multidrug resistance complicates the treatment of cytomegalovirus (CMV) infection. Improved genotypic detection of impending drug resistance may follow from recent technical advances. A severely T-cell-depleted patient with chronic lymphocytic leukemia developed CMV pneumonia and high plasma viral loads that were poorly responsive to antiviral therapy. Serial plasma specimens were analyzed for mutant viral populations by conventional and high-throughput deep-sequencing methods. Uncharacterized mutations were phenotyped for drug resistance using recombinant viruses. Conventional genotyping detected viruses with the UL97 kinase substitution C607Y after ganciclovir treatment, a transient subpopulation of UL54 polymerase L773V mutants first detected 8 weeks after foscarnet was started, and a subpopulation of a mutant with deletion of UL54 codons 981 and 982 2 months after the addition of cidofovir. Deep sequencing of the same serial specimens revealed the same UL54 mutants sooner, along with a more complex evolution of known and newly recognized mutant subpopulations missed by conventional sequencing. The UL54 exonuclease substitutions D413N, K513R, and C539G were newly shown to confer ganciclovir-cidofovir resistance, while L773V was shown to confer foscarnet resistance and add to the ganciclovir resistance conferred by UL97 C607Y. Increased sequencing depth provided a more timely and detailed diagnosis of mutant viral subpopulations that evolved with changing anti-CMV therapy.

Multiplex nucleic acid amplification test for diagnosis of dengue fever, malaria, and leptospirosis.

Dengue, leptospirosis, and malaria are among the most common etiologies of systemic undifferentiated febrile illness (UFI) among travelers to the developing world, and these pathogens all have the potential to cause life-threatening illness in returned travelers. The current study describes the development of an internally controlled multiplex nucleic acid amplification test for the detection of dengue virus (DENV) and Leptospira and Plasmodium species, with a specific callout for Plasmodium falciparum (referred to as the UFI assay). During analytical evaluation, the UFI assay displayed a wide dynamic range and a sensitive limit of detection for each target, including all four DENV serotypes. In a clinical evaluation including 210 previously tested samples, the sensitivities of the UFI assay were 98% for DENV (58/59 samples detected) and 100% for Leptospira and malaria (65/65 and 20/20 samples, respectively). Malaria samples included all five Plasmodium species known to cause human disease. The specificity of the UFI assay was 100% when evaluated with a panel of 66 negative clinical samples. Furthermore, no amplification was observed when extracted nucleic acids from related pathogens were tested. Compared with whole-blood samples, the UFI assay remained positive for Plasmodium in 11 plasma samples from patients with malaria (parasitemia levels of 0.0037 to 3.4%). The syndrome-based design of the UFI assay, combined with the sensitivities of the component tests, represents a significant improvement over the individual diagnostic tests available for these pathogens.

Repressor transcription factor 7-like 1 promotes adipogenic competency in precursor cells.

The identification of factors that define adipocyte precursor potential has important implications for obesity. Preadipocytes are fibroblastoid cells committed to becoming round lipid-laden adipocytes. In vitro, this differentiation process is facilitated by confluency, followed by adipogenic stimuli. During adipogenesis, a large number of cytostructural genes are repressed before adipocyte gene induction. Here we report that the transcriptional repressor transcription factor 7-like 1 (TCF7L1) binds and directly regulates the expression of cell structure genes. Depletion of TCF7L1 inhibits differentiation, because TCF7L1 indirectly induces the adipogenic transcription factor peroxisome proliferator-activated receptor γ in a manner that can be replaced by inhibition of myosin II activity. TCF7L1 is induced by cell contact in adipogenic cell lines, and ectopic expression of TCF7L1 alleviates the confluency requirement for adipocytic differentiation of precursor cells. In contrast, TCF7L1 is not induced during confluency of non-adipogenic fibroblasts, and, remarkably, forced expression of TCF7L1 is sufficient to commit non-adipogenic fibroblasts to an adipogenic fate. These results establish TCF7L1 as a transcriptional hub coordinating cell-cell contact with the transcriptional repression required for adipogenic competency.

Pan-Tumor Analytical Validation and Osimertinib Clinical Validation in EGFR Mutant Non-Small-Cell Lung Cancer, Supporting the First Next-Generation Sequencing Liquid Biopsy in Vitro Diagnostic.

Comprehensive genotyping is necessary to identify therapy options for patients with advanced cancer; however, many cancers are not tested, partly because of tissue limitations. Next-generation sequencing (NGS) liquid biopsies overcome some limitations, but clinical validity is not established and adoption is limited. Herein, clinical bridging studies used pretreatment plasma samples and data from FLAURA (NCT02296125; n = 441) and AURA3 (NCT02151981; n = 450) pivotal studies to demonstrate clinical validity of Guardant360 CDx (NGS LBx) to identify patients with advanced EGFR mutant non-small-cell lung cancer who may benefit from osimertinib. The primary end point was progression-free survival (PFS). Patients with EGFR mutation as identified by NGS LBx had significant PFS benefit with first-line osimertinib over standard of care (15.2 versus 9.6 months; hazard ratio, 0.41; P < 0.0001) and with later-line osimertinib over chemotherapy (8.3 versus 4.2 months; hazard ratio, 0.34; P < 0.0001). PFS benefits were similar to the original trial cohorts selected by tissue-based EGFR testing. Analytical validation included accuracy, precision, limit of detection, and specificity. Analytical validity was established for EGFR mutation detection and pan-tumor profiling. Panel-wide limit of detection was 0.1% to 0.5%, with 98% to 100% per-sample specificity. Patients with EGFR mutant non-small-cell lung cancer by NGS LBx had improved PFS with osimertinib, confirming clinical validity. Analytical validity was established for guideline-recommended therapeutic targets across solid tumors. The resulting US Food and Drug Administration approval of NGS LBx demonstrated safety and effectiveness for its intended use and is expected to improve adherence to guideline-recommended targeted therapy use.

Severe hepatitis associated with an echovirus 18 infection in an immune-compromised adult.

Enteroviruses are recognized as important pathogens in pediatric patients; however, they are often overlooked as etiologic agents of disease in adults. Here, we report a case of echovirus 18-associated severe systemic infection and acute liver failure in an adult hematopoietic stem cell transplant recipient. Additionally, we illustrate the utility of molecular methods for the detection and typing of enteroviral infections.

A sensitive multiplex, real-time PCR assay for prospective detection of Shiga toxin-producing Escherichia coli from stool samples reveals similar incidences but variable severities of non-O157 and O157 infections in northern California.

Rapid and accurate detection of Shiga toxin-producing Escherichia coli (STEC) of all serotypes from patients with diarrhea is critical for medical management and for the prevention of ongoing transmission. In this prospective study, we assessed the performance of a multiplex, real-time PCR assay targeting stx1 and stx2 for the detection of O157 and non-O157 STEC in diarrheal stool samples enriched in Gram-negative broth. We show that the assay is 100% sensitive (95% confidence interval [CI], 89.1% to 100%) and 98.5% specific (95% CI, 90.6% to 99.9%) based on a panel of 40 known STEC-positive specimens and 65 known negative specimens. During a 2-year postvalidation period, the assay detected more positive samples from patients in northern California than did culture and PCR testing performed at a public health reference laboratory, with a positive predictive value of 95.6% (95% CI, 87.6% to 99.1%). Serotyping data showed an incidence rate of 51.2% for non-O157 STEC strains, with 5.8% of patients (1/17) with non-O157 strains and 42.9% (6/14) with O157 strains (P = 0.03) developing hemolytic-uremic syndrome. The findings from this study underscore the recommendations of the CDC for laboratories to test all diarrheal stool samples from patients with acute community-acquired diarrhea for non-O157 STEC in addition to the O157 serotype by using a sensitive assay. Additionally, a survey of 17 clinical laboratories in northern California demonstrated that nearly 50% did not screen all stool specimens for the presence of Shiga toxins, indicating that many clinical microbiology laboratories still do not routinely screen all stool specimens for the presence of Shiga toxins as recommended in the 2009 CDC guidelines.

Detection of cytomegalovirus drug resistance mutations by next-generation sequencing.

Antiviral therapy for cytomegalovirus (CMV) plays an important role in the clinical management of solid organ and hematopoietic stem cell transplant recipients. However, CMV antiviral therapy can be complicated by drug resistance associated with mutations in the phosphotransferase UL97 and the DNA polymerase UL54. We have developed an amplicon-based high-throughput sequencing strategy for detecting CMV drug resistance mutations in clinical plasma specimens using a microfluidics PCR platform for multiplexed library preparation and a benchtop next-generation sequencing instrument. Plasmid clones of the UL97 and UL54 genes were used to demonstrate the low overall empirical error rate of the assay (0.189%) and to develop a statistical algorithm for identifying authentic low-abundance variants. The ability of the assay to detect resistance mutations was tested with mixes of wild-type and mutant plasmids, as well as clinical CMV isolates and plasma samples that were known to contain mutations that confer resistance. Finally, 48 clinical plasma specimens with a range of viral loads (394 to 2,191,011 copies/ml plasma) were sequenced using multiplexing of up to 24 specimens per run. This led to the identification of seven resistance mutations, three of which were present in <20% of the sequenced population. Thus, this assay offers more sensitive detection of minor variants and a higher multiplexing capacity than current methods for the genotypic detection of CMV drug resistance mutations.

BK polyomavirus subtype III in a pediatric renal transplant patient with nephropathy.

BK polyomavirus (BKV) is an emerging pathogen in immunocompromised individuals. BKV subtype III is rarely identified and has not previously been associated with disease. Here we provide the whole-genome sequence of a subtype III BKV from a pediatric kidney transplant patient with polyomavirus-associated nephropathy.

Autoimmune kidney disease and impaired engulfment of apoptotic cells in mice with macrophage peroxisome proliferator-activated receptor gamma or retinoid X receptor alpha deficiency.

Autoimmune glomerulonephritis is a common manifestation of systemic lupus erythematosus (SLE). In this study, we show that mice lacking macrophage expression of the heterodimeric nuclear receptors PPARγ or RXRα develop glomerulonephritis and autoantibodies to nuclear Ags, resembling the nephritis seen in SLE. These mice show deficiencies in phagocytosis and clearance of apoptotic cells, and they are unable to acquire an anti-inflammatory phenotype upon feeding of apoptotic cells, which is critical for the maintenance of self-tolerance. These results demonstrate that stimulation of PPARγ and RXRα in macrophages facilitates apoptotic cell engulfment, and they provide a potential strategy to avoid autoimmunity against dying cells and to attenuate SLE.

Retinol saturase promotes adipogenesis and is downregulated in obesity.

Adipocyte differentiation is controlled by many transcription factors, but few known downstream targets of these factors are necessary for adipogenesis. Here we report that retinol saturase (RetSat), which is an enzyme implicated in the generation of dihydroretinoid metabolites, is induced during adipogenesis and is directly regulated by the transcription factor peroxisome proliferator activated receptor gamma (PPARgamma). Ablation of RetSat dramatically inhibited adipogenesis but, surprisingly, this block was not overcome by the putative product of RetSat enzymatic activity. On the other hand, ectopic RetSat with an intact, but not a mutated, FAD/NAD dinucleotide-binding motif increased endogenous PPARgamma transcriptional activity and promoted adipogenesis. Indeed, RetSat was not required for adipogenesis when cells were provided with exogenous PPARgamma ligands. In adipose tissue, RetSat is expressed in adipocytes but is unexpectedly downregulated in obesity, most likely owing to infiltration of macrophages that we demonstrate to repress RetSat expression. Thiazolidinedione treatment reversed low RetSat expression in adipose tissue of obese mice. Thus, RetSat plays an important role in the biology of adipocytes, where it favors normal differentiation, yet is reduced in the obese state. RetSat is thus a novel target for therapeutic intervention in metabolic disease.

Longitudinal monitoring by next-generation sequencing of plasma cell-free DNA in ALK rearranged NSCLC patients treated with ALK tyrosine kinase inhibitors.

BACKGROUND: Patients with ALK-rearranged non-small cell lung cancer (ALK+ NSCLC) inevitably acquire resistance to ALK inhibitors. Longitudinal monitoring of cell-free plasma DNA (cfDNA) next-generation sequencing (NGS) could predict the response and resistance to tyrosine kinase inhibitor (TKI) therapy in ALK+ NSCLC. METHODS: Patients with ALK+ NSCLC determined by standard tissue testing and planned to undergo TKI therapy were prospectively recruited. Plasma was collected at pretreatment, 2 months-post therapy, and at progression for cfDNA-NGS analysis, Guardant 360. RESULTS: Among 92 patients enrolled, circulating tumor DNA (ctDNA) was detected in 69 baseline samples (75%): 43 ALK fusions (62.3%) and two ALK mutations without fusion (2.8%). Two patients showed ALK-resistance mutations after ceritinib; G1202R, and co-occurring G1202R and T1151R. Eight patients developed ALK resistance mutations after crizotinib therapy; L1196M (n = 5), G1269A (n = 1), G1202R (n = 1), and co-occurring F1174L, G1202R, and G1269A (n = 1). Absence of ctDNA at baseline was significantly associated with longer progression-free survival (PFS; median 36.1 vs. 11.4 months, p = 0.0049) and overall survival (OS; not reached vs. 29.3 months, p = 0.0200). ctDNA clearance at 2 months (n = 29) was associated with significantly longer PFS (25.4 vs. 11.6 months, p = 0.0012) and OS (not reached vs. 26.1 months, p = 0.0307) than those without clearance (n = 22). Patients with co-occurring TP53 alterations and ALK fusions at baseline (n = 16) showed significantly shorter PFS (7.28 vs. 13.0 months, p = 0.0307) than those without TP53 alterations (n = 25). CONCLUSIONS: cfDNA-NGS facilitates detection of ALK fusions and resistance mutations, assessment of prognosis, and monitoring dynamic changes of genomic alterations in ALK+ NSCLC treated with ALK-TKI.

Serial Monitoring of Circulating Tumor DNA by Next-Generation Gene Sequencing as a Biomarker of Response and Survival in Patients With Advanced NSCLC Receiving Pembrolizumab-Based Therapy.

Although the majority of patients with metastatic non-small-cell lung cancer (mNSCLC) lacking a detectable targetable mutation will receive pembrolizumab-based therapy in the frontline setting, predicting which patients will experience a durable clinical benefit (DCB) remains challenging. MATERIALS AND METHODS: Patients with mNSCLC receiving pembrolizumab monotherapy or in combination with chemotherapy underwent a 74-gene next-generation sequencing panel on blood samples obtained at baseline and at 9 weeks. The change in circulating tumor DNA levels on-therapy (molecular response) was quantified using a ratio calculation with response defined by a > 50% decrease in mean variant allele fraction. Patient response was assessed using RECIST 1.1; DCB was defined as complete or partial response or stable disease that lasted > 6 months. Progression-free survival and overall survival were recorded. RESULTS: Among 67 patients, 51 (76.1%) had > 1 variant detected at a variant allele fraction > 0.3% and thus were eligible for calculation of molecular response from paired baseline and 9-week samples. Molecular response values were significantly lower in patients with an objective radiologic response (log mean 1.25% v 27.7%, P < .001). Patients achieving a DCB had significantly lower molecular response values compared to patients with no durable benefit (log mean 3.5% v 49.4%, P < .001). Molecular responders had significantly longer progression-free survival (hazard ratio, 0.25; 95% CI, 0.13 to 0.50) and overall survival (hazard ratio, 0.27; 95% CI, 0.12 to 0.64) compared with molecular nonresponders. CONCLUSION: Molecular response assessment using circulating tumor DNA may serve as a noninvasive, on-therapy predictor of response to pembrolizumab-based therapy in addition to standard of care imaging in mNSCLC. This strategy requires validation in independent prospective studies.

New developments in adipogenesis.

The obesity epidemic has focused attention on adipose tissue and the development of fat cells (i.e. adipocytes), which is known as adipogenesis. Peroxisome proliferator-activated receptor gamma and CCAAT/enhancer-binding proteins have emerged as master regulators of adipogenesis, and recent genome-wide studies have indicated widespread overlap in their transcriptional targets. In addition, new evidence has implicated many other factors as positive and negative regulators of adipocyte development. This review highlights recent advances in the field of adipogenesis, including newly identified determinants of brown adipocytes, the function of which is to burn rather than store energy. Improved understanding of brown and white adipocyte origins and the integrative biology of adipogenesis might lead to more effective strategies for the treatment of obesity and metabolic disease.

Absence of bacterially induced RELMbeta reduces injury in the dextran sodium sulfate model of colitis.

Although inflammatory bowel disease (IBD) is the result of a dysregulated immune response to commensal gut bacteria in genetically predisposed individuals, the mechanism(s) by which bacteria lead to the development of IBD are unknown. Interestingly, deletion of intestinal goblet cells protects against intestinal injury, suggesting that this epithelial cell lineage may produce molecules that exacerbate IBD. We previously reported that resistin-like molecule beta (RELMbeta; also known as FIZZ2) is an intestinal goblet cell-specific protein that is induced upon bacterial colonization whereupon it is expressed in the ileum and colon, regions of the gut most often involved in IBD. Herein, we show that disruption of this gene reduces the severity of colitis in the dextran sodium sulfate (DSS) model of murine colonic injury. Although RELMbeta does not alter colonic epithelial proliferation or barrier function, we show that recombinant protein activates macrophages to produce TNF-alpha both in vitro and in vivo. RELMbeta expression is also strongly induced in the terminal ileum of the SAMP1/Fc model of IBD. These results suggest a model whereby the loss of epithelial barrier function by DSS results in the activation of the innate mucosal response by RELMbeta located in the lumen, supporting the hypothesis that this protein is a link among goblet cells, commensal bacteria, and the pathogenesis of IBD.