Th17 Cell Induction by Adhesion of Microbes to Intestinal Epithelial Cells.

Intestinal Th17 cells are induced and accumulate in response to colonization with a subgroup of intestinal microbes such as segmented filamentous bacteria (SFB) and certain extracellular pathogens. Here, we show that adhesion of microbes to intestinal epithelial cells (ECs) is a critical cue for Th17 induction. Upon monocolonization of germ-free mice or rats with SFB indigenous to mice (M-SFB) or rats (R-SFB), M-SFB and R-SFB showed host-specific adhesion to small intestinal ECs, accompanied by host-specific induction of Th17 cells. Citrobacter rodentium and Escherichia coli O157 triggered similar Th17 responses, whereas adhesion-defective mutants of these microbes failed to do so. Moreover, a mixture of 20 bacterial strains, which were selected and isolated from fecal samples of a patient with ulcerative colitis on the basis of their ability to cause a robust induction of Th17 cells in the mouse colon, also exhibited EC-adhesive characteristics.

Gut microorganisms act together to exacerbate inflammation in spinal cords.

Accumulating evidence indicates that gut microorganisms have a pathogenic role in autoimmune diseases, including in multiple sclerosis1. Studies of experimental autoimmune encephalomyelitis (an animal model of multiple sclerosis)2,3, as well as human studies4-6, have implicated gut microorganisms in the development or severity of multiple sclerosis. However, it remains unclear how gut microorganisms act on the inflammation of extra-intestinal tissues such as the spinal cord. Here we show that two distinct signals from gut microorganisms coordinately activate autoreactive T cells in the small intestine that respond specifically to myelin oligodendrocyte glycoprotein (MOG). After induction of experimental autoimmune encephalomyelitis in mice, MOG-specific CD4+ T cells are observed in the small intestine. Experiments using germ-free mice that were monocolonized with microorganisms from the small intestine demonstrated that a newly isolated strain in the family Erysipelotrichaceae acts similarly to an adjuvant to enhance the responses of T helper 17 cells. Shotgun sequencing of the contents of the small intestine revealed a strain of Lactobacillus reuteri that possesses peptides that potentially mimic MOG. Mice that were co-colonized with these two strains showed experimental autoimmune encephalomyelitis symptoms that were more severe than those of germ-free or monocolonized mice. These data suggest that the synergistic effects that result from the presence of these microorganisms should be considered in the pathogenicity of multiple sclerosis, and that further study of these microorganisms may lead to preventive strategies for this disease.

Inhibitory effect of isomaltodextrin on tyrosine metabolite production in rat gut microbiota.

We examined the effect of isomaltodextrin (IMD), a soluble dietary fiber, on production of putrefactive products by intestinal bacteria using a tyrosine load test to measure phenol production in IMD-treated rats. We observed a significant increase in phenol and p-cresol concentrations in rats administered with only tyrosine, but not for rats co-administered tyrosine and IMD. To elucidate the mechanism of this effect, we analyzed the intestinal microbiota in each group and found that although IMD had no direct effect on the proportion of bacteria known to produce phenols, it did alter the balance of intestinal microbiota. The results suggested that changes in the intestinal microbiota composition reduced the metabolic capacity for tyrosine and in turn suppressed production of phenol or p-cresol, putrefactive products in the intestine.

Molecular mechanisms of Streptococcus pneumoniae-targeted autophagy via pneumolysin, Golgi-resident Rab41, and Nedd4-1-mediated K63-linked ubiquitination.

Streptococcus pneumoniae is the most common causative agent of community-acquired pneumonia and can penetrate epithelial barriers to enter the bloodstream and brain. We investigated intracellular fates of S. pneumoniae and found that the pathogen is entrapped by selective autophagy in pneumolysin- and ubiquitin-p62-LC3 cargo-dependent manners. Importantly, following induction of autophagy, Rab41 was relocated from the Golgi apparatus to S. pneumoniae-containing autophagic vesicles (PcAV), which were only formed in the presence of Rab41-positive intact Golgi apparatuses. Moreover, subsequent localization and regulation of K48- and K63-linked polyubiquitin chains in and on PcAV were clearly distinguishable from each other. Finally, we found that E3 ligase Nedd4-1 was recruited to PcAV and played a pivotal role in K63-linked polyubiquitin chain (K63Ub) generation on PcAV, promotion of PcAV formation, and elimination of intracellular S. pneumoniae. These findings suggest that Nedd4-1-mediated K63Ub deposition on PcAV acts as a scaffold for PcAV biogenesis and efficient elimination of host cell-invaded pneumococci.

Obesity-induced gut microbial metabolite promotes liver cancer through senescence secretome.

Obesity has become more prevalent in most developed countries over the past few decades, and is increasingly recognized as a major risk factor for several common types of cancer. As the worldwide obesity epidemic has shown no signs of abating, better understanding of the mechanisms underlying obesity-associated cancer is urgently needed. Although several events were proposed to be involved in obesity-associated cancer, the exact molecular mechanisms that integrate these events have remained largely unclear. Here we show that senescence-associated secretory phenotype (SASP) has crucial roles in promoting obesity-associated hepatocellular carcinoma (HCC) development in mice. Dietary or genetic obesity induces alterations of gut microbiota, thereby increasing the levels of deoxycholic acid (DCA), a gut bacterial metabolite known to cause DNA damage. The enterohepatic circulation of DCA provokes SASP phenotype in hepatic stellate cells (HSCs), which in turn secretes various inflammatory and tumour-promoting factors in the liver, thus facilitating HCC development in mice after exposure to chemical carcinogen. Notably, blocking DCA production or reducing gut bacteria efficiently prevents HCC development in obese mice. Similar results were also observed in mice lacking an SASP inducer or depleted of senescent HSCs, indicating that the DCA-SASP axis in HSCs has key roles in obesity-associated HCC development. Moreover, signs of SASP were also observed in the HSCs in the area of HCC arising in patients with non-alcoholic steatohepatitis, indicating that a similar pathway may contribute to at least certain aspects of obesity-associated HCC development in humans as well. These findings provide valuable new insights into the development of obesity-associated cancer and open up new possibilities for its control.

Treg induction by a rationally selected mixture of Clostridia strains from the human microbiota.

Manipulation of the gut microbiota holds great promise for the treatment of inflammatory and allergic diseases. Although numerous probiotic microorganisms have been identified, there remains a compelling need to discover organisms that elicit more robust therapeutic responses, are compatible with the host, and can affect a specific arm of the host immune system in a well-controlled, physiological manner. Here we use a rational approach to isolate CD4(+)FOXP3(+) regulatory T (Treg)-cell-inducing bacterial strains from the human indigenous microbiota. Starting with a healthy human faecal sample, a sequence of selection steps was applied to obtain mice colonized with human microbiota enriched in Treg-cell-inducing species. From these mice, we isolated and selected 17 strains of bacteria on the basis of their high potency in enhancing Treg cell abundance and inducing important anti-inflammatory molecules--including interleukin-10 (IL-) and inducible T-cell co-stimulator (ICOS)--in Treg cells upon inoculation into germ-free mice. Genome sequencing revealed that the 17 strains fall within clusters IV, XIVa and XVIII of Clostridia, which lack prominent toxins and virulence factors. The 17 strains act as a community to provide bacterial antigens and a TGF-ß-rich environment to help expansion and differentiation of Treg cells. Oral administration of the combination of 17 strains to adult mice attenuated disease in models of colitis and allergic diarrhoea. Use of the isolated strains may allow for tailored therapeutic manipulation of human immune disorders.

Oral faecal microbiota transplantation for the treatment of Clostridium difficile-associated diarrhoea in a dog: a case report.

BACKGROUND: Successful clinical outcomes of faecal microbiota transplantation (FMT) for recurrent Clostridium difficile infection have been reported in humans and a marmoset. However, it has been unclear whether oral FMT was effective for the treatment of C. difficile-associated diarrhoea in dogs. CASE PRESENTATION: An 8-month-old, intact male French bulldog was presented with a 4-month history of intermittent large bowel diarrhoea. Physical and clinical examinations did not identify any specific causes for diarrhoea. Real-time PCR analysis and immunochromatography detected C. difficile antigen and toxin A&B genes and proteins in a faecal sample. Based on these findings, diarrhoea in the dog was considered to be induced by C. difficile-associated colitis. The dog was treated with oral FMT, in which a faecal solution obtained from a healthy beagle was orally administered to the subject. Stool consistency and frequency and faecal blood and mucus became normal 2-3 days after oral FMT, and real-time PCR analysis and immunochromatography was negative for C. difficile antigen and toxin A&B genes and proteins. No adverse events were observed. CONCLUSION: The present case report demonstrated that oral FMT was an effective treatment for C. difficile-associated diarrhoea in a dog. The findings in this report provide a rationale to evaluate clinical efficacy of oral FMT for other gastrointestinal diseases in dogs.

Fecal metabolite of a gnotobiotic mouse transplanted with gut microbiota from a patient with Alzheimer's disease.

Studies of Alzheimer's disease are based on model mice that have been altered by transgenesis and other techniques to elicit pathogenesis. However, changes in the gut microbiota were recently suggested to diminish cognitive function in patients, as well as in model mice. Accordingly, we have created model mice of the human gut microbiota by transplanting germ-free C57BL/6N mice with fecal samples from a healthy volunteer and from an affected patient. These humanized mice were stably colonized and reproduced the bacterial diversity in donors. Remarkably, performance on Object Location Test and Object Recognition Test was significantly reduced in the latter than in the former at 55 weeks of age, suggesting that gut microbiota transplanted from an affected patient affects mouse behavior. In addition, metabolites related to the nervous system, including γ-aminobutyrate, taurine, and valine, were significantly less abundant in the feces of mice transplanted with microbiota from the affected patient.

Gonadal steroid hormone secretion during the juvenile period depends on host-specific microbiota and contributes to the development of odor preference.

The host microbial community is thought to have an important role in the host endocrine system and behavioral phenotype. We investigated chronological changes of levels of gonadal hormones and corticosterone in the feces of 4- to 8-week-old female germ-free (GF) mice, and conducted odor preference test at 8 weeks of age. We further evaluated the developmental impact of the microbial community by analyzing 4-week-old GF mice orally administered the fecal microbiota of specific pathogen-free (SPF) mice or guinea pigs (GF-SPF mice or GF-Guinea pig mice). The fecal estradiol, progesterone, and corticosterone levels of GF mice were lower than those of SPF mice. Furthermore, the increased levels in GF mice were suggested to be caused by colonization of microbiota of SPF mice or guinea pigs. However, the degree of recovery of progesterone and corticosterone by microbiota of guinea pigs was lower than that by SPF mice. In odor preference tests, interestingly, female GF mice preferred female odors to male odors, although this preference was not seen in other mice. These findings suggested that the microbial community plays an important role in the development of the host endocrine system for gonadal hormones and corticosterone, and odor preference in mice.

Fecal microbiota transplantation for patients with steroid-resistant acute graft-versus-host disease of the gut.

Increasing evidence indicates that the gut microbiota is closely associated with acute graft-versus-host disease (aGVHD) in stem cell transplantation (SCT). Fecal microbiota transplantation (FMT) could represent an alternative treatment option for aGVHD. However, FMT for SCT patients carries a potential risk of infection by infused microbiota because of the severely immunosuppressed status. We therefore conducted a pilot study to evaluate the safety of FMT in SCT. A total of 4 patients with steroid-resistant (n = 3) or steroid-dependent gut aGVHD (n = 1) received FMT. No severe adverse events attributed to FMT were observed. All patients responded to FMT, with 3 complete responses and 1 partial response. Temporal dynamics of microbiota seemed to be linked to the gut condition of patients and peripheral effector regulatory T cells also increased during response to FMT. FMT was safely performed in our patients and might offer a novel therapeutic option for aGVHD. This trial was registered at the University Hospital Medical Information Network (https://upload.umin.ac.jp/cgi-open-bin/icdr_e/ctr_view.cgi?recptno=R000017575) as #UMIN000015115.

Confounding effects of microbiome on the susceptibility of TNFSF15 to Crohn's disease in the Ryukyu Islands.

Crohn's disease (CD) involves chronic inflammation in the gastrointestinal tract due to dysregulation of the host immune response to the gut microbiome. Even though the host-microbiome interactions are likely contributors to the development of CD, a few studies have detected genetic variants that change bacterial compositions and increase CD risk. We focus on one of the well-replicated susceptible genes, tumor necrosis factor superfamily member 15 (TNFSF15), and apply statistical analyses for personal profiles of genotypes and salivary microbiota collected from CD cases and controls in the Ryukyu Islands, southernmost islands of the Japanese archipelago. Our association test confirmed the susceptibility of TNFSF15 in the Ryukyu Islands. We found that the recessive model was supported to fit the observed genotype frequency of risk alleles slightly better than the additive model, defining the genetic effect on CD if a pair of the chromosomes in an individual consists of all risk alleles. The combined analysis of haplotypes and salivary microbiome from a small set of samples showed a significant association of the genetic effect with the increase of Prevotella, which led to a significant increase of CD risk. However, the genetic effect on CD disappeared if the abundance of Prevotella was low, suggesting the genetic contribution to CD is conditionally independent given a fixed amount of Prevotella. Although our statistical power is limited due to the small sample size, these results support an idea that the genetic susceptibility of TNFSF15 to CD may be confounded, in part, by the increase of Prevotella.

Clinical impact of pre-transplant gut microbial diversity on outcomes of allogeneic hematopoietic stem cell transplantation.

Post-transplant microbial diversity in the gastrointestinal tract is closely associated with clinical outcomes following allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, little is known about the impact of the fecal microbiota before allo-HSCT. We analyzed fecal samples approximately 2 weeks before conditioning among 107 allo-HSCT recipients between 2013 and 2015. Microbial analysis was performed using 16S rRNA gene sequencing. Operational taxonomic unit-based microbial diversity was estimated by calculating the Shannon index. Patients were classified into three groups based on the diversity index: low (<2), intermediate (2, 3), and high (>3) diversity (18 (16.8%), 48 (44.9%), and 41 (38.3%) patients, respectively). There were no significant differences in the 20-month overall survival, cumulative incidence of relapse, and non-relapse mortality among three groups. The cumulative incidence of grade II to IV acute graft-versus-host disease (aGVHD) was similar among the three groups (low 55.6%; intermediate 35.4%; high 48.8%, p = 0.339, at day 100). Furthermore, we found no differences in the cumulative incidence of grade II to IV acute gastrointestinal GVHD among the three groups (low 38.9%; intermediate 21.3%; high 24.4%, p = 0.778, at day 100). Regarding the composition of microbiota before allo-HSCT, aGVHD patients showed a significantly higher abundance of phylum Firmicutes (p < 0.01) and a lower tendency for Bacteroidetes (p = 0.106) than non-aGVHD patients. Maintenance of Bacteroidetes throughout allo-HSCT may be a strategy to prevent aGVHD.

Bifidobacteria can protect from enteropathogenic infection through production of acetate.

The human gut is colonized with a wide variety of microorganisms, including species, such as those belonging to the bacterial genus Bifidobacterium, that have beneficial effects on human physiology and pathology. Among the most distinctive benefits of bifidobacteria are modulation of host defence responses and protection against infectious diseases. Nevertheless, the molecular mechanisms underlying these effects have barely been elucidated. To investigate these mechanisms, we used mice associated with certain bifidobacterial strains and a simplified model of lethal infection with enterohaemorrhagic Escherichia coli O157:H7, together with an integrated 'omics' approach. Here we show that genes encoding an ATP-binding-cassette-type carbohydrate transporter present in certain bifidobacteria contribute to protecting mice against death induced by E. coli O157:H7. We found that this effect can be attributed, at least in part, to increased production of acetate and that translocation of the E. coli O157:H7 Shiga toxin from the gut lumen to the blood was inhibited. We propose that acetate produced by protective bifidobacteria improves intestinal defence mediated by epithelial cells and thereby protects the host against lethal infection.

Faecal transplantation for the treatment of Clostridium difficile infection in a marmoset.

BACKGROUND: The common marmoset has been used as an experimental animal for various purposes. Because its average weight ranges from 250 to 500 g, weight loss quickly becomes critical for sick animals. Therefore, effective and non-stressful treatment for chronic diseases, including diarrhoea, is essential. CASE PRESENTATION: We report a case in which faecal microbiota transplantation (FMT) led to immediate recovery from chronic and recurrent diarrhoea caused by Clostridium difficile infection. A male common marmoset experienced chronic diarrhoea after antibiotic treatments. The animal experienced severe weight loss, and a faecal sample was confirmed to be C. difficile-positive but was negative for protozoa. Metronidazole was partially effective at the first administration but not after the recurrence of the clinical signs. Then, oral FMT was administered to the subject by feeding fresh faeces from healthy individuals mixed with the marmoset's usual food. We monitored the faeces by categorization into four groups: normal, loose, diarrhoea, and watery. After the first day of FMT treatment, the marmoset underwent a remarkable recovery from diarrhoea, and after the fourth day of treatment, a test for C. difficile was negative. The clinical signs did not recur. The marmoset recovered from sinusitis and bilateral dacryocystitis, which also did not recur, as a by-product of the improvement in its general health caused by the cessation of diarrhoea after the FMT. CONCLUSION: This is the first reported case of successful treatment of a marmoset using oral FMT. As seen in human patients, FMT was effective for the treatment of recurrent C. difficile infection in a captive marmoset.

Bacillus hisashii sp. nov., isolated from the caeca of gnotobiotic mice fed with thermophile-fermented compost.

A taxonomic study was performed on 15 bacterial isolates from the caeca of gnotobiotic mice that had been fed with thermophile-fermented compost. The 15 isolates were thermophilic, Gram-stain-positive, facultatively anaerobic, endospore-forming bacteria, and were most closely related to Bacillus thermoamylovorans CNCM I-1378T. The 16S rRNA gene sequence of strain N-11T, selected as representative of this new group, showed a similarity of 99.4 % with Bacillus thermoamylovorans CNCM I-1378T, 94.7 % with Bacillus thermolactis R-6488T, and 94.4 % with Bacillus kokeshiiformis MO-04T. The isolates were then classified into two distinct groups based on a (GTG)5-fingerprint analysis. Two isolates, N-11T and N-21, were the representatives of these two groups, respectively.` The N-11T and N-21 isolates showed 66-71 % DNA-DNA relatedness with one other, but had less than 37 % DNA-DNA relatedness with B. thermoamylovorans LMG 18084T. The other 13 isolates showed DNA-DNA relatedness values above 74 % with the N-11T isolate. All 15 isolates grew at 25-60 °C (optimum 50 °C), pH 6-8 (optimum pH 7) and were capable of growing on a medium containing 6 % (w/v) NaCl (optimum 0.5 %). The 15 isolates could be distinguished from B. thermoamylovorans LMG 18084T because they showed Tween 80 hydrolysis activity and did not produce acid from melibiose. The major fatty acids were anteiso-C15 : 0, C16 : 0, iso-C15 : 0, iso-C14 : 0 and iso-C16 : 0. The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and several unidentified phospholipids. The diagnostic diamino acid in the cell-wall peptidoglycan was meso-diaminopimelic acid. The menaquinone was MK-7. The DNA G+C content was 37.9 mol%. Based on the phenotypic properties, the 15 strains represent a novel species of the genus Bacillus, for which the name Bacillus hisashii sp. nov. is proposed. The type strain is N-11T ( = NRBC 110226T = LMG 28201T).

Mariner-based transposon mutagenesis for Bacteroides species.

Bacteroides is one of the most predominant groups of human gut microbiota. Recent metagenomic analyses and studies on gnotobiotic mice demonstrated the tight association of Bacteroides with epithelial function, the gut immune system and systemic metabolism in the host. The mariner family transposon shows relatively low target site specificity and has hosts ranging from prokaryotes to eukaryotes. Thereby, random mutagenesis using the mariner family transposon is expected to identify key molecules for human-Bacteroides symbiosis. In this study, we constructed the plasmid pMI07 to deliver the gene cassette (ermF/ITR), which harbors the erythromycin resistant marker (ermF) and the inverted repeat sequences (ITRs) recognized by Himar1 transposase, to Bacteroides via electrotransformation. pMI07 successfully delivered ermF/ITR to the Bacteroides genomes and generated thousands of insertion mutants/µg of pMI07 in B. thetaiotaomicron, B. fragilis, B. ovatus, and also, although to a lesser extent, B. vulgatus. Analyses of the ermF/ITR insertion sites in B. thetaiotaomicron and B. vulgatus revealed that the cassette targeted the dinucleotide TA and integrated into the genomes in an unbiased manner. The data reported here will provide useful information for transposon mutagenesis in Bacteroides species, which will enable identification of the genes responsible for their unique phenotypes.

Anti-inflammatory and Intestinal Barrier-protective Activities of Commensal Lactobacilli and Bifidobacteria in Thoroughbreds: Role of Probiotics in Diarrhea Prevention in Neonatal Thoroughbreds.

We previously isolated the commensal bacteria lactobacilli and bifidobacteria from the Thoroughbred intestine and prepared the horse probiotics LacFi(TM), consisting of Lactobacillus ruminis KK14, L. equi KK 15, L. reuteri KK18, L. johnsonii KK21, and Bifidobacterium boum HU. Here, we found that the five LacFi(TM) constituent strains remarkably suppressed pro-inflammatory interleukin-17 production in mouse splenocytes stimulated with interleukin-6 and transforming growth factor-ß. The protective effects of the probiotic on impaired intestinal barrier function were evaluated in Caco-2 cells treated with tumor necrosis factor-α. Evaluation of transepithelial resistance showed that all the strains exhibited intestinal barrier protective activity, with significant suppression of barrier impairment by L. reuteri KK18. The LacFi(TM) constituent strains were detected in neonatal LacFi(TM)-administered Thoroughbred feces using polymerase chain reaction denaturing gradient gel electrophoresis and culture methods. These five strains were found to be the predominant lactobacilli and bifidobacteria in the intestinal microbiota of LacFi(TM)-administered Thoroughbreds. Administration of LacFi(TM) to neonatal Thoroughbreds decreased diarrhea incidence from 75.9% in the control group (n=29 neonatal Thoroughbreds) to 30.7% in the LacFi(TM)-administered group (n=101 neonatal Thoroughbreds) immediately after birth to 20 weeks after birth. LacFi(TM) treatment also prevented diarrhea especially at and around 4 weeks and from 10 to 16 weeks. The duration of diarrhea was also shorter in the probiotics-administered group (7.4 ± 0.8 days) than in the control group (14.0 ± 3.2 days). These results indicate that the LacFi(TM) probiotics regulates intestinal function and contributes to diarrhea prevention.

Aqueous extracts of Rhizopus oryzae induced nitric oxide production in rat hepatocyte cell line RLN-10.

Aqueous extracts of Rhizopus oryzae (Aq-ROU) have a broad range of physiological activity. Here we identified a new physiological effect of Aq-ROU in rat hepatocyte cell line RLN-10. Aq-ROU induced the accumulation of nitrite, a stable metabolite nitric oxide (NO), in cell culture medium and induced potent diaminofluorescein-FM diacetate staining in the cells. Real-time reverse transcriptase (RT)-PCR analysis showed marked inducible NO synthase gene expression. Additionally, markedly enhanced expression of p22(phox) and temporally increased expression of NADPH oxidase1 indicated that superoxide was produced. Nuclear translocation of nuclear factor-kappa (NF-κ) B p65 increased remarkably following Aq-ROU and following lipopolysaccharide treatment, a potent activator of NF-κB. Ammonium pyrrolidine-1-carbodithioate, an inhibitor of NF-κB, inhibited NO production following Aq-ROU treatment. Our data indicate that Aq-ROU induces NO production and potentially the production of superoxide, which may contribute to the broad range of physiological effects observed for Aq-ROU ingested by animals.

Nitric oxide induces vascular endothelial growth factor expression in the rat placenta in vivo and in vitro.

We investigated the role of nitric oxide (NO) in vascular endothelial growth factor (VEGF) expression in the rat placenta. A nitric oxide synthase (NOS) inhibitor, N(G)-nitro-L-arginine-methyl ester (L-NAME), was constantly infused into pregnant rats 6-24 h before sacrifice on gestational day (GD) 15.5. NO production declined to about 15% of the control level as monitored by NO trapping and electron paramagnetic resonance spectroscopy. VEGF mRNA expression was temporally decreased by L-NAME, but recovered to normal levels after 24 h of treatment, whereas hypoxia inducible factor (HIF)-1α and induced NOS (iNOS) expression increased. VEGF expression decreased significantly in placental explants after 6 h of co-treatment with L-NAME and lipopolysaccharide, an iNOS inducer. Our data indicate that NO induce VEGF expression in vivo and in vitro in the rat placenta, suggesting that peaked NO production was maintained by a reciprocal relationship between NO and VEGF via HIF-1α.