Inflammatory bowel disease (IBD) is a chronic gastrointestinal disease whose incidence has risen worldwide in recent years. Accumulating evidence shows that oxidative stress plays an essential role in the pathogenesis and progression of IBD. This review highlights the generation of reactive oxygen species (ROS) and antioxidant defense mechanisms in the gastrointestinal (GI) tract, the involvement of oxidative stress signaling in the initiation and progression of IBD and its relationships with genetic susceptibility and the mucosal immune response. In addition, potential therapeutic strategies for IBD that target oxidative stress signaling are reviewed and discussed. Though substantial progress has been made in understanding the role of oxidative stress in IBD in humans and experimental animals, the underlying mechanisms are still not well defined. Thus, further studies are needed to validate how oxidative stress signaling is involved in and contributes to the development of IBD.

BackgroundCombination therapy is one of the most effective tools for limiting the emergence of drug resistance in pathogens. Despite the widespread adoption of combination therapy across diseases, drug resistance rates continue to rise, leading to failing treatment regimens. The mechanisms underlying treatment failure are well studied, but the processes governing successful combination therapy are poorly understood. We address this question by studying the population dynamics of Mycobacterium tuberculosis within tuberculosis patients undergoing treatment with different combinations of antibiotics.ResultsBy combining very deep whole genome sequencing (~1000-fold genome-wide coverage) with sequential sputum sampling, we were able to detect transient genetic diversity driven by the apparently continuous turnover of minor alleles, which could serve as the source of drug-resistant bacteria. However, we report that treatment efficacy has a clear impact on the population dynamics: sufficient drug pressure bears a clear signature of purifying selection leading to apparent genetic stability. In contrast, M. tuberculosis populations subject to less drug pressure show markedly different dynamics, including cases of acquisition of additional drug resistance.ConclusionsOur findings show that for a pathogen like M. tuberculosis, which is well adapted to the human host, purifying selection constrains the evolutionary trajectory to resistance in effectively treated individuals. Nonetheless, we also report a continuous turnover of minor variants, which could give rise to the emergence of drug resistance in cases of drug pressure weakening. Monitoring bacterial population dynamics could therefore provide an informative metric for assessing the efficacy of novel drug combinations.Electronic supplementary materialThe online version of this article (doi:10.1186/s13059-017-1196-0) contains supplementary material, which is available to authorized users.

BackgroundChemotherapy can induce premature ovarian insufficiency (POI) and reduce fertility in young female patients. Currently, there is no effective therapy for POI. Human amnion-derived mesenchymal stem cells (hAD-MSCs) may be a promising seed cell for regenerative medicine. This study investigated the effects and mechanisms of hAD-MSC transplantation on chemotherapy-induced POI in rats.MethodsChemotherapy-induced POI rat models were established by intraperitoneal injection of cyclophosphamide. Seventy-two female SD rats were randomly divided into control, POI, and hAD-MSC-treated groups. hAD-MSCs were labeled with PKH26 and injected into the tail veins of POI rats. To examine the underlying mechanisms, the differentiation of transplanted hAD-MSCs in the POI ovaries was analyzed by immunofluorescent staining. The in vitro expression of growth factors secreted by hAD-MSCs in hAD-MSC-conditioned media (hAD-MSC-CM) was analyzed by ELISA. Sixty female SD rats were divided into control, POI, and hAD-MSC-CM-treated groups, and hAD-MSC-CM was injected into the bilateral ovaries of POI rats. After hAD-MSC transplantation or hAD-MSC-CM injection, serum sex hormone levels, estrous cycles, ovarian pathological changes, follicle counts, granulosa cell (GC) apoptosis, and Bcl-2, Bax, and VEGF expression in ovaries were examined.ResultsPKH26-labeled hAD-MSCs mainly homed to ovaries after transplantation.hAD-MSC transplantation reduced ovarian injury and improved ovarian function in rats with POI. Transplanted hAD-MSCs were only located in the interstitium of ovaries, rather than in follicles, and did not express the typical markers of oocytes and GCs, which are ZP3 and FSHR, respectively. hAD-MSCs secreted FGF2, IGF-1, HGF, and VEGF, and those growth factors were detected in the hAD-MSC-CM. hAD-MSC-CM injection improved the local microenvironment of POI ovaries, leading to a decrease in Bax expression and an increase in Bcl-2 and endogenous VEGF expression in ovarian cells, which inhibited chemotherapy-induced GC apoptosis, promoted angiogenesis and regulated follicular development, thus partly reducing ovarian injury and improving ovarian function in rats with POI.ConclusionshAD-MSC transplantation can improve ovarian function in rats with chemotherapy-induced POI at least partly through a paracrine mechanism. The presence of a paracrine mechanism accounting for hAD-MSC-mediated recovery of ovarian function might be attributed to the growth factors secreted by hAD-MSCs.

Autophagy has emerged as a critical pathway in tumor development. S100A4 plays important roles in tumor metastasis, but its role in regulating autophagy has not been well characterized. In this study, we found that S100A4 was significantly upregulated in lung adenocarcinoma tissues. Clinical investigation demonstrated that high expression level of S100A4 was associated with tumor size and advanced tumor grades of lung adenocarcinoma patients. Moreover, our results revealed that extracellular S100A4 or overexpression of S100A4 inhibited starvation-induced autophagy and promoted cell proliferation in lung cancer cells in vitro; whereas small interfering RNA (siRNA)-mediated suppression of S100A4 increased autophagy and reduced cell viability in both A549 and LLC cells. Additionally, S100A4 inhibited starvation-induced autophagy to promote tumor cell viability via the Wnt pathway. Increased expression of β-catenin consistently led to a decreased LC3-II protein abundance. Further, the inhibitory effect of S100A4 on autophagy and its promotion role in cell proliferation was abolished in A549 and LLC cells using the receptor for advanced glycation end products (RAGE)-specific inhibitor (FPS-ZM1). S100A4-deficient mice showed retarded tumor development. This effect was well correlated with increased expression of autophagy markers. Our findings demonstrate that S100A4 promotes lung tumor development through inhibiting autophagy in a β-catenin signaling and S100A4 receptor RAGE-dependent manner, which provides a novel mechanism of S100A4-associated promotion of tumor development.

BackgroundHuman amnion-derived mesenchymal stem cells (hAD-MSCs) have the features of mesenchymal stem cells (MSCs). Low-intensity pulsed ultrasound (LIPUS) can promote the expression of various growth factors and anti-inflammatory molecules that are necessary to keep the follicle growing and to reduce granulosa cell (GC) apoptosis in the ovary. This study aims to explore the effects of LIPUS-pretreated hAD-MSC transplantation on chemotherapy-induced primary ovarian insufficiency (POI) in rats.MethodsThe animals were divided into control, POI, hAD-MSC treatment, and LIPUS-pretreated hAD-MSC treatment groups. POI rat models were established by intraperitoneal injection of cyclophosphamide (CTX). The hAD-MSCs isolated from the amnion were exposed to LIPUS or sham irradiation for 5 consecutive days and injected into the tail vein of POI rats. Expression and secretion of growth factors promoted by LIPUS in hAD-MSCs were detected by real-time quantitative polymerase chain reaction (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA) in vitro. Estrous cycle, serum sex hormone levels, follicle counts, ovarian pathological changes, GC apoptosis, Bcl2 and Bax expression, and pro-inflammatory cytokine levels in ovaries were examined.ResultsPrimary hAD-MSCs were successfully isolated from the amnion. LIPUS promoted the expression and secretion of growth factors in hAD-MSCs in vitro. Both hAD-MSC and LIPUS-pretreated hAD-MSC transplantation increased the body and reproductive organ weights, improved ovarian function, and reduced reproductive organ injuries in POI rats. Transplantation of hAD-MSCs increased the Bcl-2/Bax ratio and reduced GC apoptosis and ovarian inflammation induced by chemotherapy in ovaries. These effects could be improved by pretreatment with LIPUS on hAD-MSCs.ConclusionBoth hAD-MSC transplantation and LIPUS-pretreated hAD-MSC transplantation can repair ovarian injury and improve ovarian function in rats with chemotherapy-induced POI. LIPUS-pretreated hAD-MSC transplantation is more advantageous for reducing inflammation, improving the local microenvironment, and inhibiting GC apoptosis induced by chemotherapy in ovarian tissue of POI rats.

Adult hippocampal neurogenesis plays a pivotal role in learning and memory. The suppression of hippocampal neurogenesis induced by an increase of oxidative stress is closely related to cognitive impairment. Neural stem cells which persist in the adult vertebrate brain keep up the production of neurons over the lifespan. The balance between pro-oxidants and anti-oxidants is important for function and surviving of neural stem cells. Ginsenoside Rg1 is one of the most active components of Panax ginseng, and many studies suggest that ginsenosides have antioxidant properties. This research explored the effects and underlying mechanisms of ginsenoside Rg1 on protecting neural stem cells (NSCs) from oxidative stress. The sub-acute ageing of C57BL/6 mice was induced by subcutaneous injection of D-gal (120 mg kg day) for 42 day. On the 14th day of D-gal injection, the mice were treated with ginsenoside Rg1 (20 mg kg day, intraperitoneally) or normal saline for 28 days. The study monitored the effects of Rg1 on proliferation, senescence-associated and oxidative stress biomarkers, and Akt/mTOR signalling pathway in NSCs. Compared with the D-gal group, Rg1 improved cognitive impairment induced by D-galactose in mice by attenuating senescence of neural stem cells. Rg1 also decreased the level of oxidative stress, with increased the activity of superoxide dismutase and glutathione peroxidase in vivo and in vitro. Rg1 furthermore reduced the phosphorylation levels of protein kinase B (Akt) and the mechanistic target of rapamycin (mTOR) and down-regulated the levels of downstream p53, p16, p21 and Rb in D-gal treated NSCs. The results suggested that the protective effect of ginsenoside Rg1 on attenuating cognitive impairment in mice and senescence of NSCs induced by D-gal might be related to the reduction of oxidative stress and the down-regulation of Akt/mTOR signaling pathway.

With the growing population, aging, extended lifespans and anti-aging have become popular areas of research in the life and social sciences. With increasing age, the structure and function of the testes, the spermatogenetic and androgen-producing organ in the male reproductive system, gradually declines. Ginsenoside Rg1 is an extract of Panax ginseng in traditional Chinese medicine. The extract facilitates anti-aging through its anti-inflammatory and antioxidant properties. However, it has not been reported whether ginsenoside Rg1 delays testicular aging. The present study established D-galactose (D-gal)-induced aging mouse models to examine the protective effects of ginsenoside Rg1 on the structure and function of the testes, and the underlying mechanism. A total of 60 healthy specific pathogen-free male C57BL/6 mice were randomly divided into four groups: Control group; Rg1 group; D-gal + Rg1 group; and D-gal group. The tissues of the mice were used for further experiments. The present study further investigated the effects of Rg1 on the volume of serum testosterone, the testicular index, testicular microscopic structures, the senescence of spermatogenetic cells, the apoptosis of spermatogenetic cells, the activity of the antioxidant enzymes, the levels of inflammatory cytokines, and the levels of S-phase kinase-associated protein (p19), cyclin-dependent kinase inhibitor 1 (p21) and cellular tumor antigen p53 (p53) in D-gal-induced aging mice. In general, compared with the D-gal group, the treatment of Rg1 increased the testis index, serum testosterone level and the active content of superoxide dismutase and the total antioxidant capacity. The percentage of senescence-associated β-galactosidase-positive cells, the level of apoptosis and the volume of methane dicarboxylic aldehyde, tumor necrosis factor-α, interleukin (IL)-1β and IL-6 in testicular tissues were significantly decreased, and the expression of p19, p53 and p21 was downregulated due to the treatment with Rg1. The results of the present study demonstrated that ginsenoside Rg1 was able to protect the testes against D-gal-induced aging in mice. In addition, the protective effect of Rg1 may be achieved via antioxidation and downregulation of the p19/p53/p21 signaling pathway.

Mesenchymal stem cells (MSCs), with their capacity for self-renewal and differentiation into various cell types, are important seed cells for stem cell therapy. MSCs exhibit potent pathotropic migratory properties that make them attractive for use in tumor prevention and therapy. However, little is known about the underlying molecular mechanisms that link MSCs to the targeted tumor cells. This study investigated the inhibitory effect and mechanism of MSCs on human hepatoma HepG2 cells using co-culture and conditioned medium system and animal transplantation model. The HepG2 cells were co-cultured with MSCs or treated with conditional media derived from MSCs cultures in vitro. Results of methylthiazolyldiphenyl tetrazolium assay and flow cytometric assay showed that the proliferation and apoptosis of HepG2 cells decreased and increased, respectively. Reverse transcription polymerase chain reaction analysis showed that the expression levels of bcl-2, c-Myc, β-catenin, and survivin were downregulated. The results of enzyme-linked immunosorbent assay and Western blot proved that MSCs secreted Dkk-1 to inhibit the expression of Wnt signaling pathway-related factors (bcl-2, c-Myc, β-catenin, and survivin) in tumor cells, consequently inhibiting the proliferation and promoting the apoptosis of HepG2 cells. Animal transplantation experiment showed that tumor growth was significantly inhibited when HepG2 cells were co-injected with MSCs into nude mice. These results suggested that MSCs inhibited the growth and promoted the apoptosis of HepG2 cells in a dose-dependent manner. This study provided a new approach and experimental basis for cancer therapy. This study also proved that the Wnt signaling pathway may have a function in MSC-mediated tumor cell inhibition.