Serum GM-CSF level is a predictor of treatment response to tocilizumab in rheumatoid arthritis patients: a prospective observational cohort study.

BACKGROUND: The aim of this prospective observational cohort study was to unveil the predictors of treatment response to tocilizumab (TCZ) therapy in rheumatoid arthritis (RA) patients, in terms of clinical characteristics and serum proinflammatory cytokines, especially to explore the predictive value of granulocyte macrophage-colony stimulating factor (GM-CSF). METHODS: Active adult RA patients with inadequate response to MTX intending to receive TCZ therapy were recruited prospectively in the study. A total of 174 severe RA patients were included for the identification of the associations between treatment response and the following characteristic features: demographics, medications, disease activity, serum proinflammatory cytokines and so on. RESULTS: Disease duration (OR = 0.996), tender joint count (TJC)/68 (OR = 0.943), neutrophil ratio (W4/baseline) (OR = 0.224), the high level of GM-CSF > 5 ng/ml (OR = 0.414) at baseline were the independent adverse predictors of good response assessed by clinical disease activity index (CDAI) at week 24 (W24) for TCZ therapy in RA patients. Moreover, DAS28-ESR (OR = 2.951, P = 0.002) and the high level of GM-CSF > 10 ng/ml at baseline (OR = 5.419, P = 0.002) were independent predictors of poor response, but not the high level of GM-CSF > 5 ng/ml (OR = 2.713, P = 0.054). The patients in the high GM-CSF group had significantly higher DAS28-ESR and serum levels of cytokines (IL-17A, IL-1ß, IL-6, TNF-α) at baseline, as well as significantly higher rate of non-good response (62.8% vs. 39.4%, P = 0.010) and poor response (27.9% vs. 9.1%, P = 0.004) than the low GM-CSF group at W24. In addition, poor responders had significantly higher levels of GM-CSF with concomitant increase in the serum levels of IL-17A and IL-1ß at baseline than those in moderate and good response groups, while serum levels of IL-6 and TNF-α at baseline were not significantly different in three response groups. CONCLUSION: The high levels of GM-CSF (> 5 ng/ml and > 10 ng/ml) at baseline were the independent predictors of non-good response and poor response to TCZ at W24 respectively. The high level of GM-CSF at baseline is a marker of high disease activity and a predictor of poor response to TCZ in severe RA patients, which may facilitate the development of individualized treatment strategies for refractory RA.

Changes in metabolic parameters and serum YKL-40 levels in Chinese rheumatoid arthritis patients during tocilizumab therapy.

OBJECTIVE: To investigate the metabolic changes during therapy of tocilizumab (TCZ) and methotrexate (MTX) in non-diabetic rheumatoid arthritis (RA) patients and for the first time explore the associations between metabolic parameters and serum YKL-40 (sYKL-40) levels. METHODS: We enrolled active non-diabetic RA patients who were refractory to MTX. Patients received intravenous TCZ (8 mg/kg) once every 4 weeks combined with MTX for 24 weeks. Metabolic parameters and sYKL-40 levels were measured before TCZ infusion at baseline, week 4, week 12, and week 24. Correlations were assessed by the Spearman's rank correlation analysis. RESULTS: A total of 91 non-diabetic RA patients were enrolled in this study. At week 24, we observed a significant elevation in body mass index (BMI), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and triglycerides (TG) levels. In contrast, there was a significant decrease in TC/HDL­C ratio. No apparent changes in insulin resistance were found. Additionally, we detected a significant reduction in sYKL-40 levels during the study. At week 24, changes in sYKL-40 levels showed a significant negative correlation (r = -0.334, p = 0.002) with changes in TC levels. CONCLUSION: The combined therapy of TCZ and MTX resulted in a significant increase in BMI and lipid levels, while an evident decrease in the TC/HDL­C ratio and sYKL-40 levels in RA patients. Additionally, there was a significant correlation between the decrease in sYKL-40 levels and the increase in TC levels during treatment with TCZ and MTX. Key Points • Lipid levels elevated significantly and sYKL-40 levels decreased obviously after therapy of TCZ combined with MTX in Chinese RA patients. • There was a significant correlation between the increase in TC levels and the decrease in sYKL-40 levels during treatment with TCZ and MTX in RA patients.

Ethylene signaling modulates air humidity responses in plants.

Air humidity significantly impacts plant physiology. However, the upstream elements that mediate humidity sensing and adaptive responses in plants remain largely unexplored. In this study, we define high humidity-induced cellular features of Arabidopsis plants and take a quantitative phosphoproteomics approach to obtain a high humidity-responsive landscape of membrane proteins, which we reason are likely the early checkpoints of humidity signaling. We found that a brief high humidity exposure (i.e., 0.5 h) is sufficient to trigger extensive changes in membrane protein abundance and phosphorylation. Enrichment analysis of differentially regulated proteins reveals high humidity-sensitive processes such as 'transmembrane transport', 'response to abscisic acid', and 'stomatal movement'. We further performed a targeted screen of mutants, in which high humidity-responsive pathways/proteins are disabled, to uncover genes mediating high humidity sensitivity. Interestingly, ethylene pathway mutants (i.e., ein2 and ein3eil1) display a range of altered responses, including hyponasty, reactive oxygen species level, and responsive gene expression, to high humidity. Furthermore, we observed a rapid induction of ethylene biosynthesis genes and ethylene evolution after high humidity treatment. Our study sheds light on the potential early signaling events in humidity perception, a fundamental but understudied question in plant biology, and reveals ethylene as a key modulator of high humidity responses in plants.

G-MDSC-derived exosomes mediate the differentiation of M-MDSC into M2 macrophages promoting colitis-to-cancer transition.

BACKGROUNDS: In inflammatory bowel disease microenvironment, transdifferentiation of myeloid-derived suppressor cells (MDSCs) and M2 macrophage accumulation are crucial for the transition of colitis-to-cancer. New insights into the cross-talk and the underling mechanism between MDSCs and M2 macrophage during colitis-to-cancer transition are opening new avenues for colitis-associated cancer (CAC) prevention and treatment. METHODS: The role and underlying mechanism that granulocytic MDSCs (G-MDSCs) or exosomes (Exo) regulates the differentiation of monocytic MDSCs (M-MDSCs) into M2 macrophages were investigated using immunofluorescence, FACS, IB analysis, etc, and employing siRNA and antibodies. In vivo efficacy and mechanistic studies were conducted with dextran sulfate sodium-induced CAC mice, employed IL-6 Abs and STAT3 inhibitor. RESULTS: G-MDSCs promote the differentiation of M-MDSC into M2 macrophages through exosomal miR-93-5 p which downregulating STAT3 activity in M-MDSC. IL-6 is responsible for miR-93-5 p enrichment in G-MDSC exosomes (GM-Exo). Mechanistically, chronic inflammation-driven IL-6 promote the synthesis of miR-93-5 p in G-MDSC via IL-6R/JAK/STAT3 pathway. Early use of IL-6 Abs enhances the effect of STAT3 inhibitor against CAC. CONCLUSIONS: IL-6-driven secretion of G-MDSC exosomal miR-93-5 p promotes the differentiation of M-MDSC into M2 macrophages and involves a STAT3 signaling mechanism that promote colitis-to-cancer transition. Combining STAT3 inhibitors with strategies that inhibit IL-6-mediated G-MDSC exosomal miR-93-5 p production is beneficial for the prevention and treatment of CAC.

Clinical features and independent predictors of Behçet's disease associated with myelodysplastic syndrome.

OBJECTIVES: To investigate the correlation of Behçet's disease (BD) with myelodysplastic syndrome (MDS) and identify the predictive risk factors in Chinese patients. METHODS: A retrospective study of BD associated with MDS (BD-MDS) patients from the First Affiliated Hospital of Zhengzhou University was conducted. RESULTS: Among 15 BD-MDS patients, 10 were females and 5 males. While 13 (86.7%) patients had abnormal karyotype, 11 patients with trisomy 8. 10 (66.7%) had gastrointestinal (GI) involvement. Compared with 60 general BD patients without MDS, the BD-MDS patients were significantly older. In addition, fever and GI involvement were more common in BD-MDS patients, whereas these patients had lower levels of leukocyte count, haemoglobin, and platelet count (p<0.05). Logistic regression analysis showed that GI involvement, low haemoglobin, and high ESR level were independently associated with the development of MDS in BD patients. BD-MDS patients with GI involvement (IBD-MDS) were usually much older and have more fever than IBD patients without MDS, as well as lower leukocyte count, haemoglobin level, platelet count, and higher erythrocyte sedimentation rate (ESR) and C-reactive protein levels (p<0.05). By comparison with 60 primary MDS patients without BD, the BD-MDS patients had more abnormal karyotypes and more trisomy 8 (p<0.05), while the distribution of 2016 WHO subtypes of MDS and IPSS-R categories were similar. CONCLUSIONS: Our findings suggest that cytogenetic abnormalities, especially trisomy 8, may play a role in the association of GI involvement, BD, and MDS. GI involvement, low haemoglobin, and high ESR level were independent predictors for MDS development in BD patients.

Hyperhubeins A-I, Bioactive Sesquiterpenes with Diverse Skeletons from Hypericum hubeiense.

Nine new sesquiterpenes, hyperhubeins A-I (1-9), and 14 known analogues (10-23) were isolated from the aerial portions of Hypericum hubeiense. Their structures and absolute configurations were determined unambiguously via spectroscopic analysis, single-crystal X-ray diffraction, and electronic circular dichroism calculations. Compounds 1-3 possess an unprecedented sesquiterpene carbon skeleton. Further, a plausible biosynthetic pathway from farnesyl diphosphate (FPP) is proposed. The isolated phytochemicals were evaluated for neuroprotective and anti-neuroinflammatory properties in vitro. Compounds 1, 2, 5-8, 14, and 21 displayed notable neuroprotective activity against hydrogen peroxide (H2O2)-induced lesions in PC-12 cells at 10 µM. Additionally, compounds 1, 2, 12, and 13 exhibited inhibition of lipopolysaccharide (LPS)-induced nitric oxide (NO) production in BV-2 microglial cells, with their IC50 values ranging from 4.92 to 6.81 µM. Possible interactions between these bioactive compounds and inducible nitric oxide synthase (iNOS) were predicted via molecular docking. Moreover, Western blotting indicated that compound 12 exerted anti-neuroinflammatory activity by suppressing LPS-stimulated expression of toll-like receptor-4 (TLR-4) and inhibiting consequent activation of nuclear factor-kappa-B (NF-κB) signaling.

Protective effect of Eucommia ulmoides Oliver male flowers on ethanol-induced DNA damage in mouse cerebellum and cerebral cortex.

Ethanol is a principal ingredient of alcoholic beverages with potential neurotoxicity and genotoxicity, and the ethanol-associated oxidative DNA damage in the central nervous system is well documented. Natural product may offer new options to protect the brain against ethanol-induced neurotoxicity. The male flower of Eucommia ulmoides (EUF) Oliver has been extensively utilized as the tea, the healthy hot drink on the market. In this study, 19 constituents in the effective fraction of EUF were identified by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). In the single-cell gel electrophoresis assay, EUF was observed to ameliorate DNA damage in mouse cerebellum and cerebral cortex caused by acute ethanol administration, which was further confirmed by the morphological observation. The protective effects of EUF were associated with increasing total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-PX) activities, and a decrease in nitric oxide (NO), malondialdehyde (MDA), 8-hydroxy-2'-deoxyguanosine (8-OHdG), and kelch-like ECH-associated protein-1 (Keap1) levels. Molecular docking results demonstrated that compounds 4, 7, 9, and 16 from EUF have a strong affinity to the Keap1 Kelch domain to hinder the interaction of nuclear factor-erythroid 2-related factor 2 (Nrf2) with Keap1. These findings suggest that EUF is a potent inhibitor of ethanol-induced brain injury possibly via the inhibition of oxidative stress.

Bacterial effectors manipulate plant abscisic acid signaling for creation of an aqueous apoplast.

Phytopathogens like Pseudomonas syringae induce "water soaking" in the apoplastic space of plant leaf tissue as a key virulence mechanism. Water soaking is commonly observed in diverse pathosystems, yet the underlying physiological basis remains largely elusive. Here, we show that one of the strong P. syringae water-soaking inducers, AvrE, alters the regulation of abscisic acid (ABA) to induce ABA signaling, stomatal closure, and, thus, water soaking. AvrE binds and inhibits the function of Arabidopsis type one protein phosphatases (TOPPs), which negatively regulate ABA by suppressing SnRK2s, a key node of the ABA signaling pathway. The topp12537 quintuple mutants display significantly enhanced water soaking after P. syringae inoculation, whereas the loss of the ABA pathway dampens P. syringae-induced water soaking and disease. Our study uncovers the hijacking of ABA signaling and stomatal closure by P. syringae effectors as key mechanisms of disease susceptibility.

Revealing the structure-activity relationship of two Cu-porphyrin-based metal-organic frameworks for the electrochemical CO2-to-HCOOH transformation.

The eCO2RR activity is correlated to the internal structural character of the catalyst. We employed two types of structural models of porphyrin-based MOFs of PCN-222(Cu) and PCN-224(Cu) into heterogeneous catalysis to illustrate the effect of structural factors on the eCO2RR performance. The composite catalyst PCN-222(Cu)/C displays better activity and selectivity (η = 450 mV, FEHCOOH = 44.3%, j = 3.2 mA cm-2) than PCN-224(Cu)/C (η = 450 mV, FEHCOOH = 34.1%, j = 2.4 mA cm-2) for the CO2 reduction to HCOOH in the range of -0.7--0.9 V (vs. RHE) due to its higher BET surface area, CO2 uptake, and a larger pore diameter. It is interesting that PCN-224(Cu)/C displays better performance in the range of -0.4--0.6 V (vs. RHE) due to its greater heat of adsorption, Qst and a higher affinity for CO2 molecule, which could promote the capture of CO2 onto the exposed active sites. As a result, PCN-224(Cu)/C exhibits better stability for the long-term electrolysis.

Role of myeloid-derived suppressor cells in the promotion and immunotherapy of colitis-associated cancer.

Colitis-associated cancer (CAC) is a specific type of colorectal cancer that develops from inflammatory bowel disease (IBD). Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells that are essential for the pathological processes of inflammation and cancer. Accumulating evidence indicates that MDSCs play different but vital roles during IBD and CAC development and impede CAC immunotherapy. New insights into the regulatory network of MDSCs in the CAC pathogenesis are opening new avenues for developing strategies to enhance the effectiveness of CAC treatment. In this review, we explore the role of MDSCs in chronic inflammation, dysplasia and CAC and summarize the potential CAC therapeutic strategies based on MDSC blockade.

Expression Status And Prognostic Value Of M6A-associated Genes in Gastric Cancer.

Purpose: Gastric cancer (GC) is a primary cause of cancer-associated mortality worldwide. N6-methyladenosine (m6A) is one of the most common RNA modifications that involves in the progression of numerous cancers. However, the expression status and function of m6A-related genes in gastric cancer is still not well understood. The current study is aimed to investigate the expression status and determinate prognostic value of m6A-related genes in gastric cancer. Methods: m6A-asssociated gene expression was evaluated via analyzing the expression data of GC patients from the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) database. The protein expression levels of m6A-associated molecules were further validated by immunohistochemical (IHC) staining data from GC tissue microarray (TMA) cohort and Human Protein Atlas (HPA) database. Kaplan-Meier analysis was performed to assess the prognostic value of m6A-associated genes in gastric cancer. Risk score model was established by lasso COX regression analysis and its prognostic predicted efficiency was assessed by the receiver-operator characteristic (ROC) curve. Cox regression analyses were used for exploring risk factors related to GC patient prognosis. Results: Most of m6A-related genes were upregulated at both mRNA and protein levels in gastric cancer tissues compared with that in normal gastric tissues. The expression levels of m6A-related genes were associated with clinicopathological features including race, age and TNM stage. High expression of WTAP and FTO predicted poor prognosis of GC patients. Survival analysis demonstrated that patients with high-risk scores had worse overall survival (OS) and ROC curves suggested the prediction performance for gastric patients. Moreover, Cox regression analyses indicated that m6A risk model score was a prognostic factor for OS and FTO upregulation might be a potential independent prognostic factor for recurrence-free survival (RFS) in gastric cancer patients. Conclusion: m6A-related genes were dysregulated in GC and were closely associated with prognosis of GC patients. FTO might serve as a novel prognostic biomarker for gastric cancer, while the m6A-related risk score might be informative for risk assessment and prognostic stratification.

Portable pulsed xenon ultraviolet light disinfection in a teaching hospital animal laboratory in China.

An animal laboratory in a teaching hospital is a possible cause of cross infection. We aimed to assess the infection control in our animal laboratory and evaluate the disinfectant effects of a portable pulsed xenon ultraviolet (PX-UV) machine. Samples were taken from the surface of research tables, other high touch places, such as doorknobs, weighing scales, and handles of trolleys, and from air in the barrier system pre- and post-manual cleaning and post-PX-UV disinfection. The bacteria types were identified. We found that routine manual cleaning significantly reduced bacterial colony form unit (CFU)/cm2 (P = .02), and the median of CFU/cm2 reduced from 0.5 pre-cleaning to zero post-cleaning. PX-UV disinfection also significantly reduced residual bacterial counts (P = .002), with the highest counts 10 pre-PX-UV disinfection and 1 afterwards. Without manual cleaning, PX-UV disinfected surfaces significantly (P < .001), median count 6 pre-PX-UV disinfection and zero afterwards. PX-UV significantly reduced bacterial colony counts in the air with the median count falling from 6 to zero (P < .001). Some of the 21 species of pathogens we identified in the current study are pathogenic, resistant to antibiotics, and able to cause nosocomial infections and zoonosis. PX-UV reduced counts of most of the pathogens. PX-UV is an effective agent against these pathogens.

MDSCs: Key Criminals of Tumor Pre-metastatic Niche Formation.

The emergence of disseminated metastases remains the primary cause of mortality in cancer patients. Formation of the pre-metastatic niche (PMN), which precedes the establishment of tumor lesions, is critical for metastases. Bone marrow-derived myeloid cells (BMDCs) are indispensable for PMN formation. Myeloid-derived suppressor cells (MDSCs) are a population of immature myeloid cells that accumulate in patients with cancer and appear in the early PMN. The mechanisms by which MDSCs establish the pre-metastatic microenvironment in distant organs are largely unknown, although MDSCs play an essential role in metastasis. Here, we summarize the key factors associated with the recruitment and activation of MDSCs in the PMN and review the mechanisms by which MDSCs regulate PMN formation and evolution. Finally, we predict the potential value of MDSCs in PMN detection and therapy.

Axon initial segment plasticity accompanies enhanced excitation of visual cortical neurons in aged rats.

Recent studies have indicated that the structure of the axon initial segment (AIS) of neurons is highly plastic in response to changes in neuronal activity. Whether an age-related enhancement of neuronal responses in the visual cortex is coupled with plasticity of AISs is unknown. Here, we compare the AIS length and the distribution of Nav1.6, a key Na ion channel in action potential (AP) initiation, along the AIS of layer II/III neurons in the primary visual cortex (V1) of young adult and aged rats, which were examined previously in a single-unit recording study. In that study, we found that V1 neurons in aged rats showed a significantly higher spontaneous activity and stronger visually evoked responses than did neurons in young rats. Our present study shows that the mean AIS length of layer II/III neurons in the V1 area of aged rats was significantly shorter than that of young adult rats. Further, the proportion of AIS with the Nav1.6 distribution was also reduced significantly in aged rats relative to young rats, as indicated by a decrease in the mean Nav1.6 immunofluorescence optical density within AISs and a specific decrease in Nav1.6 immunofluorescence optical density near the proximal region of the AIS. Our results indicate that aging results in both shortening of AISs and reduction of Nav1.6 Na ion channel distribution along AISs, which accompanies enhanced neuronal activity. This age-related morphological plasticity may lower the AP amplitude by reducing Na ion entry during AP initiation, spare ATPs consumed by Na ion pumps during membrane potential restoration, and thus balance the energy expenditure caused by an increased firing rate of cortical neurons during the aging process.

Changes in GABAergic markers accompany degradation of neuronal function in the primary visual cortex of senescent rats.

Numerous studies have reported age-dependent degradation of neuronal function in the visual cortex and have attributed this functional decline to weakened intracortical inhibition, especially GABAergic inhibition. However, whether this type of functional decline is linked to compromised GABAergic inhibition has not been fully confirmed. Here, we compared the neuronal response properties and markers of GABAergic inhibition in the primary visual cortex (V1) of young adult and senescent rats. Compared with those of young adult rats, old rats' V1 neurons exhibited significantly increased visually evoked responses and spontaneous activity, a decreased signal-to-noise ratio and reduced response selectivity for the stimulus orientation and motion direction. Additionally, the ratio of GABA-positive neurons to total cortical neurons in old rats was significantly decreased compared with that in young rats. Expression of the key GABA-synthesizing enzyme GAD67 was significantly lower in old rats than in young rats, although GAD65 expression showed a marginal difference between the two age groups. Further, expression of an important GABAA receptor subunit, GABAAR α1, was significantly attenuated in old rats relative to young ones. These results demonstrate that ageing may result in decreased GABAergic inhibition in the visual cortex and that this decrease in GABAergic inhibition accompanies neuronal function degradation.

Characterization of a highly virulent and antimicrobial-resistant Acinetobacter baumannii strain isolated from diseased chicks in China.

Poultry husbandry is a very important aspect of the agricultural economy in China. However, chicks are often susceptible to infectious disease microorganisms, such as bacteria, viruses and parasites, causing large economic losses in recent years. In the present study, we isolated an Acinetobacter baumannii strain, CCGGD201101, from diseased chicks in the Jilin Province of China. Regression analyses of virulence and LD50 tests conducted using healthy chicks confirmed that A. baumannii CCGGD201101, with an LD50 of 1.81 (±0.11) × 10(4) CFU, was more virulent than A. baumannii ATCC17978, with an LD50 of 1.73 (±0.13) × 10(7) CFU. Moreover, TEM examination showed that the pili of A. baumannii CCGGD201101 were different from those of ATCC17978. Antibiotic sensitivity analyses showed that A. baumannii CCGGD201101 was sensitive to rifampicin but resistant to most other antibiotics. These results imply that A. baumannii strain CCGGD201101 had both virulence enhancement and antibiotic resistance characteristics, which are beneficial for A. baumannii survival under adverse conditions and enhance fitness and invasiveness in the host. A. baumannii CCGGD20101, with its high virulence and antimicrobial resistance, may be one of the pathogens causing death of diseased chicks.

Dietary Restriction Affects Neuronal Response Property and GABA Synthesis in the Primary Visual Cortex.

Previous studies have reported inconsistent effects of dietary restriction (DR) on cortical inhibition. To clarify this issue, we examined the response properties of neurons in the primary visual cortex (V1) of DR and control groups of cats using in vivo extracellular single-unit recording techniques, and assessed the synthesis of inhibitory neurotransmitter GABA in the V1 of cats from both groups using immunohistochemical and Western blot techniques. Our results showed that the response of V1 neurons to visual stimuli was significantly modified by DR, as indicated by an enhanced selectivity for stimulus orientations and motion directions, decreased visually-evoked response, lowered spontaneous activity and increased signal-to-noise ratio in DR cats relative to control cats. Further, it was shown that, accompanied with these changes of neuronal responsiveness, GABA immunoreactivity and the expression of a key GABA-synthesizing enzyme GAD67 in the V1 were significantly increased by DR. These results demonstrate that DR may retard brain aging by increasing the intracortical inhibition effect and improve the function of visual cortical neurons in visual information processing. This DR-induced elevation of cortical inhibition may favor the brain in modulating energy expenditure based on food availability.

Iridoid constituents from the male flower of Eucommia ulmoides and their promotion proliferation on ESF-1.

Four new iridoids (1, 2, 12, and 13), together with nine known iridoids (3-11), were isolated from the male flowers of Eucommia ulmoides Oliver and were characterized as 3ß-methoxyartselawnin C (1), 6ß-hydroxyl-1ß,3ß-dimethoxyartsclaenin III (2), 3,4-dihydro-3ß-ethoxyasperuloside (12) and 3,4-dihydro-3ß-ethoxydesacetylasperuloside (13) by extensive analyses of their 1D and 2D NMR spectroscopy and mass spectra. All of the isolated compounds were assayed for the promoting proliferation of skin fibroblasts cell (ESF-1) and compounds 4 and 7 (5 µM) significantly stimulated the proliferation of ESF-1 cells.

Establishment of a three-step purification scheme for a recombinant protein rG17PE38 and its characteristics identification.

A protein with high purity has become an essential pre-requisite for investigating its bioactivity, molecular structure and characteristics. Therefore, the development of technologies for efficient purification of protein is urgently necessary. The objective of this study was to establish a purification protocol for a recombinant protein rG17PE38. Different forms of chromatography such as hydrophobic interaction and ion exchange chromatography were chosen as the core purification steps. The performance of each technique was optimized to meet the requirements and the purification steps were arranged in a logical way of facilitating to operate in next step. In addition, some characteristics of the protein such as stability, bioactivity and cellular location were determined. Finally, whether the protein could induce cell apoptosis was also explored. The results showed the protein purified via the suggested three-step purification scheme could obtain a purity of 95%, and its bioactivity in the form of IC50 was 17.6 ng/mL, furthermore it could keep stable at 4 °C for at least 10 days. The protein could bind on its target cell membrane specifically, and inducing cell apoptosis was demonstrated to be one of the cytotoxicity mechanisms of the protein. Results obtained in our study may provide useful information on strategies of protein purification and lay a substantial foundation for the followed animal or clinical experiments on rG17PE38.