Sequential administration of delta-tocotrienol ameliorates radiation-induced myelosuppression in mice and non-human primates through inducing G-CSF production

To date only four recombinant growth factors, including Filgrastim (rhG-CSF), have been approved by FDA as radiomitigators to ameliorate hematopoietic acute radiation syndrome (H-ARS). These approved agents are not stable under room-temperature, needing to be stored at 2-8 °C, and would not be feasible in a mass casualty scenario where rapid and cost-effective intervention is crucial. Delta-tocotrienol (δ-T3H), the most potent G-CSF-inducing agent among vitamin E isoforms, exhibited efficiency and selectivity on G-CSF production in comparison with TLR and STING agonists in mice. Five-dose δ-T3H was utilized as the optimal therapeutic regimen due to long-term G-CSF production and the best peripheral blood (PB) recovery of irradiated mice. Comparable with rhG-CSF, sequential administration of δ-T3H post-irradiation improved hematologic recovery and accelerated the regeneration of hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs) in the bone marrow (BM) and spleen of 6.5Gy irradiated mice; and consistently enhanced repopulation of BM-HSCs. In 4.0Gy irradiated nonhuman primates, δ-T3H exhibited comparable efficacy as rhG-CSF to promote PB recovery and colony-formation of BM-HPCs. Altogether, we demonstrated that sequential administration of delta-tocotrienol ameliorates radiation-induced myelosuppression in mice and non-human primates through inducing G-CSF production, indicated δ-T3H as a promising radiomitigator for the management of H-ARS, particularly in a mass casualty scenario.

Radioprotective effectiveness of a novel delta-tocotrienol prodrug on mouse hematopoietic system against 60Co gamma-ray irradiation through inducing granulocyte-colony stimulating factor production

Considering the increasing risk of nuclear attacks worldwide, the development of develop potent and safe radioprotective agents for nuclear emergencies is urgently needed. γ-tocotrienol (GT3) and δ-tocotrienol (DT3) have demonstrated a potent radioprotective effect by inducing the production of granulocyte-colony stimulating factor (G-CSF) in vivo. However, their application is limited because of their low bioavailability. The utilization of ester prodrugs can be an effective strategy for modifying the pharmacokinetic properties of drug molecules. In this study, we initially confirmed that DT3 exhibited the most significant potential for inducing G-CSF effects among eight natural vitamin E homologs. Consequently, we designed and synthesized a series of DT3 ester and ether derivatives, leading to improved radioprotective effects. The metabolic study conducted in vitro and in vivo has identified DT3 succinate 5b as a prodrug of DT3 with an approximately seven-fold higher bioavailability compared to DT3 alone. And DT3 ether derivative 8a were relatively stable and approximately 4 times more bioavailable than DT3 prototype. Furthermore, 5b exhibited superior ability to mitigate radiation-induced pancytopenia, enhance the recovery of bone marrow hematopoietic stem and progenitor cells, and promote splenic extramedullary hematopoiesis in sublethal irradiated mice. Similarly, 8a shown potential radiation protection, but its radiation protection is less than DT3. Based on these findings, we identified 5b as a DT3 prodrug, and providing an attractive candidate for further drug development.

Fluacrypyrim Protects Hematopoietic Stem and Progenitor Cells against Irradiation via Apoptosis Prevention

Ionizing radiation (IR)-induced hematopoietic injury has become a global concern in the past decade. The underlying cause of this condition is a compromised hematopoietic reserve, and this kind of hematopoietic injury could result in infection or bleeding, in addition to lethal mishaps. Therefore, developing an effective treatment for this condition is imperative. Fluacrypyrim (FAPM) is a recognized effective inhibitor of STAT3, which exhibits anti-inflammation and anti-tumor effects in hematopoietic disorders. In this context, the present study aimed to determine whether FAPM could serve as a curative agent in hematopoietic-acute radiation syndrome (H-ARS) after total body irradiation (TBI). The results revealed that the peritoneally injection of FAPM could effectively promote mice survival after lethal dose irradiation. In addition, promising recovery of peripheral blood, bone marrow (BM) cell counts, hematopoietic stem cell (HSC) cellularity, BM colony-forming ability, and HSC reconstituting ability upon FAPM treatment after sublethal dose irradiation was noted. Furthermore, FAPM could reduce IR-induced apoptosis in hematopoietic stem and progenitor cells (HSPCs) both in vitro and in vivo. Specifically, FAPM could downregulate the expressions of p53-PUMA pathway target genes, such as Puma, Bax, and Noxa. These results suggested that FAPM played a protective role in IR-induced hematopoietic damage and that the possible underlying mechanism was the modulation of apoptotic activities in HSCs.

Human body numerical simulation: An accurate model for a thigh subjected to a cold treatment

This article presents the development of a digital twin model of a thigh portion subjected to various thermal treatments. Two scenarios are investigated: cold water immersion (CWI) and whole body cryotherapy (WBC), for which the comparison of numerical results with experimental measurements validates the consistency of the developed model. The use of real geometry on a first subject demonstrates the high heterogeneity of the temperature field and the need for accurate geometry. A second subject with thicker adipose tissue highlights the impact of the subject's actual morphology on the validity of the treatment and the necessity to work with real geometry in order to optimize cold modalities and develop personalized treatments.

Threshold of 25(OH)D and consequently adjusted parathyroid hormone reference intervals: data mining for relationship between vitamin D and parathyroid hormone

PURPOSE

By recruiting reference population, we aimed to (1): estimate the 25(OH)D threshold that maximally inhibits the PTH, which can be defined as the cutoff value for vitamin D sufficiency; (2) establish the PTH reference interval (RI) in population with sufficient vitamin D.

METHODS

Study data were retrieved from LIS (Laboratory Information Management System) under literature suggested criteria, and outliers were excluded using Tukey fence method. Locally weighted regression (LOESS) and segmented regression (SR) were conducted to estimate the threshold of 25(OH)D. Multivariate linear regression was performed to evaluate the associations between PTH concentration and variables including 25(OH)D, gender, age, estimated glomerular filtration rate (EGFR), body mass index (BMI), albumin-adjusted serum calcium (aCa), serum phosphate(P), serum magnesium(Mg), and blood collection season. Z test was adopted to evaluate whether the reference interval should be stratified by determinants such as age and gender.

RESULTS

A total of 64,979 apparently healthy subjects were recruited in this study, with median (Q1, Q3) 25(OH)D of 45.33 (36.15, 57.50) nmol/L and median (Q1, Q3) PTH of 42.19 (34.24, 52.20) ng/L. The segmented regression determined the 25(OH)D threshold of 55 nmol/L above which PTH would somewhat plateau and of 22 nmol/L below which PTH would rise steeply. Multivariate linear regression suggested that gender, EGFR, and BMI were independently associated with PTH concentrations. The PTH RI was calculated as 22.17-72.72 ng/L for subjects with 25(OH)D ≥ 55 nmol/L with no necessity of stratification according to gender, age, menopausal status nor season.

CONCLUSION

This study reported 25(OH)D thresholds of vitamin D sufficiency at 55 nmol/L and vitamin D deficiency at 22 nmol/L, and consequently established PTH RIs in subjects with sufficient vitamin D for northern China population for the first time.

Disulfiram Protects Against Radiation-Induced Intestinal Injury in Mice

Radiation-induced intestinal injury (RIII) occurs after high doses of radiation exposure. RIII restricts the therapeutic efficacy of radiotherapy in cancer and increases morbidity and mortality in nuclear disasters. Currently, there is no approved agent for the prevention or treatment of RIII. Here, we reported that the disulfiram, an FDA-approved alcohol deterrent, prolonged the survival in mice after lethal irradiation. Pretreatment with disulfiram inhibited proliferation within 24 h after irradiation, but improved crypt regeneration at 3.5 days post-irradiation. Mechanistically, disulfiram promoted Lgr5+ intestinal stem cells (ISCs) survival and maintained their ability to regenerate intestinal epithelium after radiation. Moreover, disulfiram suppresses DNA damage accumulation, thus inhibits aberrant mitosis after radiation. Unexpectedly, disulfiram treatment did not inhibit crypt cell apoptosis 4 h after radiation and the regeneration of crypts from PUMA-deficient mice after irradiation was also promoted by disulfiram. In conclusion, our findings demonstrate that disulfiram regulates the DNA damage response and survival of ISCs through affecting the cell cycle. Given its radioprotective efficacy and decades of application in humans, disulfiram is a promising candidate to prevent RIII in cancer therapy and nuclear accident.

Dimethyl sulfoxide, a potent oral radioprotective agent, confers radioprotection of hematopoietic stem and progenitor cells independent of apoptosis

In mass casualty events involving radiation exposure, there is a substantial unmet need for identifying and developing an orally bioavailable agent that can be used to protect the hematopoietic stem cell pool and regenerate hematopoiesis after radiation injury. Dimethyl sulfoxide (DMSO), a free-radical scavenger, has shown therapeutic benefits in many preclinical and clinical studies. This study investigates the radioprotective effects of DMSO on oral administration. Single dose of oral DMSO administrated before irradiation conferred 100% survival of C57BL6/J mice receiving otherwise lethal as well as super-lethal radiation dose, with wide radioprotective time frame (from 15min to 4h). Oral DMSO not only protected radiation-induced acute hematopoietic stem and progenitor cell (HSPC) injury, but also ameliorated long-term BM suppression following irradiation in mice. Mechanistically, DMSO directly protected HSPC survival after irradiation in vitro and in vivo, whereas no radioprotective effect was seen in MLL-AF9-induced leukemia cells. Unexpectedly, DMSO treatment did not inhibit radiation-induced HSPC apoptosis, and the HSPC survival from Trp53-and PUMA-deficient mice after irradiation was also protected by DMSO. In conclusion, our findings demonstrate the radioprotective efficacy of oral DMSO. Given its oral efficacy and little toxicity, DMSO is an attractive candidate for human use in a wide variety of settings, including nuclear accidents and medical radiation.

Upholding ethical values and human rights at the frontier of TB research

Until recently, human rights have played a minor role in the fight against tuberculosis (TB), even less so in TB research. This is changing, however. The WHO's End TB Strategy and Ethics Guidance stress respect for human rights and ethical principles in every area of TB care, including research. The desired reductions in TB incidence and mortality are impossible without new tools and strategies to fight the disease. Yet, little suggests that the current state of TB research-including funding levels, evidence being produced, and community involvement-will alleviate concerns related to the availability, accessibility, and acceptability of TB diagnostics, drugs, and prevention in the near future. In this article, we consider these ethics concerns in relation to the right to enjoy the benefits of scientific progress and the right to health. We also reflect on community involvement in research and offer recommendations in the spirit of the rights to health and science, such as involving affected communities in all aspects of research planning, execution, and dissemination. Finally, we argue that states have a responsibility under international law for the continued realization of the right to health. This realization rests, in part, on the realization of the right to science.

Bacillus coagulans and its applications in medicine

Bacillus coagulans is a probiotic bacterium that produces spores. Due to its excellent stability, it has been widely used in medicine, food and chemical industry. Recent studies have shown that B. coagulans has therapeutic effects on intestinal diseases, such as acute diarrhoea, irritable bowel syndrome, antibiotic-related diarrhoea, constipation and colitis via modulation of the microbiota composition, host immunity and metabolism. Additionally, toxicological experiments and a large number of clinical observations have showed that B. coagulans is safe and has no effect of mutagenicity, teratogenicity or genotoxicity. This review summarises the latest advances associated with B. coagulans, from its biological features, probable action mechanisms, toxicity, and medical applications.

Bacillus coagulans and its applications in medicine

Bacillus coagulans is a probiotic bacterium that produces spores. Due to its excellent stability, it has been widely used in medicine, food and chemical industry. Recent studies have shown that B. coagulans has therapeutic effects on intestinal diseases, such as acute diarrhoea, irritable bowel syndrome, antibiotic-related diarrhoea, constipation and colitis via modulation of the microbiota composition, host immunity and metabolism. Additionally, toxicological experiments and a large number of clinical observations have showed that B. coagulans is safe and has no effect of mutagenicity, teratogenicity or genotoxicity. This review summarises the latest advances associated with B. coagulans, from its biological features, probable action mechanisms, toxicity, and medical applications.

SERS-based lateral flow assay for quantitative detection of C-reactive protein as an early bio-indicator of a radiation-induced inflammatory response in nonhuman primates

In accidental irradiation situations, rapid in-field evaluation of acute radiation syndrome is critical for effective triage and timely medical treatment of irradiated individuals. A surface-enhanced Raman scattering (SERS)-based lateral flow assay was developed for the quantitative detection of C-reactive protein (CRP) as an early bio-indicator of a radiation-induced inflammatory response in nonhuman primates. Raman reporter-embedded gold-core silver-shell nanoparticles with built-in hot spots were synthesized and conjugated with a CRP detection antibody to serve as SERS tags in the lateral flow assay. The proposed SERS-based lateral flow assay can rapidly detect CRP with a limit of detection of 0.01 ng mL-1 and quantitative analysis ability. Furthermore, the assay was applied to evaluate the CRP levels in plasma samples of irradiated nonhuman primates at 0 to 80 h after exposure to sublethal (4 Gy) and lethal (8 Gy) doses of total body irradiation (n = 3 animals per group). The plasma CRP levels increase rapidly within few hours after irradiation. The CRP level peaks are observed at 12 or 24 h after irradiation, with a concentration of 201.30, 386.06 and 475.18 μg mL-1 for the 4 Gy irradiated animals and 197.14, 69.52 and 358.03 μg mL-1 for the 8 Gy irradiated animals. The results indicate the potential application of the proposed SERS-based lateral flow assay to serve as a rapid and accurate point-of-care biodosimetry assay for the quantitative detection of bio-indicators to triage irradiated individuals in the field of a radiation accident.

Dimethyl Sulfoxide Prevents Radiation-Induced Oral Mucositis Through Facilitating DNA Double-Strand Break Repair in Epithelial Stem Cells

PURPOSE

Oral mucositis is one of the most prevalent side effects in patients undergoing radiation therapy for head and neck cancers. Current therapeutic agents such as palifermin recombinant human keratinocyte growth factor and amifostine do not efficiently or fully prevent mucositis. Dimethyl sulfoxide (DMSO), a free-radical scavenger, has shown therapeutic benefits in many preclinical and clinical studies. This study aimed to investigate the efficacy of DMSO in a clinically relevant mouse model of acute, radiation-induced oral mucositis.

METHODS AND MATERIALS

Oral mucositis was induced by a high single and fractioned irradiation of the head and neck area in C57BL/6J mice, and the effects of DMSO (by intraperitoneal injection) were assessed by macroscopic and histopathological examination. Epithelial stem and progenitor cells were analyzed by immunohistochemical staining of p63 and Ki-67, and DNA double-strand breaks (DSBs) were visualized by immunofluorescence detection of γ-H2AX. Tumor xenograft was obtained using CAL-27 cells.

RESULTS

Pretreatment with DMSO protected the oral mucosa from severe acute radiation injury, reduced the extent of radiation-induced weight loss, and had no significant effects on tumor weight in irradiated or nonirradiated xenograft mice. Furthermore, the efficacy of DMSO was superior to that of recombinant human keratinocyte growth factor and amifostine. DMSO treatment prevented the loss of proliferative lingual epithelial stem and progenitor cells upon irradiation. More interestingly, the average levels of γ-H2AX foci were significantly decreased in p63-positive epithelial stem cells at 6 hours, but not at 2 hours, after irradiation, indicating that DMSO facilitated DNA DSB repair rather than suppressing the indirect action of irradiation.

CONCLUSIONS

DMSO prevents the loss of proliferative lingual epithelial stem and progenitor cells upon irradiation by facilitating DNA DSB repair, thereby protecting against radiation-induced mucositis without tumor protection. Given its high efficacy and low toxicity, DMSO could be a potential treatment option to prevent radiation-induced oral mucositis.

Smad nuclear interacting protein 1 (SNIP1) inhibits intestinal inflammation through regulation of epithelial barrier function

Smad nuclear interacting protein 1 (SNIP1) has been implicated in the pathogenesis of inflammatory bowel disease (IBD). However, the mechanisms involved are still largely unknown. Our results demonstrated that SNIP1 was markedly decreased in intestinal epithelial cells (IEC) from IBD patients compared with healthy controls. Impaired expression of SNIP1 caused a significant decrease of transepithelial electrical resistance but an increase of fluorescein isothiocyanate-dextran flux in Caco-2 monolayers, whereas overexpression of SNIP1 reversed such effects. Overexpression of SNIP1 also inhibited the activity of NF-κB p65 and proinflammatory cytokine production (e.g., TNF-α, IL-1β, and IL-8) by IEC. Importantly, supplementation of exogenous SNIP1 significantly ameliorated intestinal mucosal inflammation in experimental colitis, characterized by less-severe intestinal epithelial barrier damage and decreased proinflammatory cytokine production. Our data thus demonstrated a novel mechanism whereby SNIP1 regulates intestinal inflammation through modulating intestinal epithelial barrier function. Targeting SNIP1 may provide a therapeutic approach for the treatment of IBD.

Hypoxia inducible factor-1α-induced interleukin-33 expression in intestinal epithelia contributes to mucosal homeostasis in inflammatory bowel disease

Intestinal epithelial cells (IECs), an important barrier to gut microbiota, are subject to low oxygen tension, particularly during intestinal inflammation. Hypoxia inducible factor-1α (HIF-1α) is expressed highly in the inflamed mucosa of inflammatory bowel disease (IBD) and functions as a key regulator in maintenance of intestinal homeostasis. However, how IEC-derived HIF-1α regulates intestinal immune responses in IBD is still not understood completely. We report here that the expression of HIF-1α and IL-33 was increased significantly in the inflamed mucosa of IBD patients as well as mice with colitis induced by dextran sulphate sodium (DSS). The levels of interleukin (IL)-33 were correlated positively with that of HIF-1α. A HIF-1α-interacting element was identified in the promoter region of IL-33, indicating that HIF-1α activity regulates IL-33 expression. Furthermore, tumour necrosis factor (TNF) facilitated the HIF-1α-dependent IL-33 expression in IEC. Our data thus demonstrate that HIF-1α-dependent IL-33 in IEC functions as a regulatory cytokine in inflamed mucosa of IBD, thereby regulating the intestinal inflammation and maintaining mucosal homeostasis.

Regulatory immune cells in regulation of intestinal inflammatory response to microbiota

The intestinal lumen harbors nearly 100 trillion commensal bacteria that exert crucial function for health. An elaborate balance between immune responses and tolerance to intestinal microbiota is required to maintain intestinal homeostasis. This process depends on diverse regulatory mechanisms, including both innate and adaptive immunity. Dysregulation of the homeostasis between intestinal immune systems and microbiota has been shown to be associated with the development of inflammatory bowel diseases (IBD) in genetically susceptible populations. In this review, we discuss the recent progress reported in studies of distinct types of regulatory immune cells in the gut, including intestinal intraepithelial lymphocytes, Foxp3(+) regulatory T cells, regulatory B cells, alternatively activated macrophages, dendritic cells, and innate lymphoid cells, and how dysfunction of this immune regulatory system contributes to intestinal diseases such as IBD. Moreover, we discuss the manipulation of these regulatory immune cells as a potential therapeutic method for management of intestinal inflammatory disorders.

Self-reported lactose intolerance in clinic patients with functional gastrointestinal symptoms: prevalence, risk factors, and impact on food choices

BACKGROUND

Many patients complain of abdominal symptoms with dairy products; however, clinical and psychosocial factors associated with self-reported lactose intolerance (SLI) have not been assessed in large studies. In particular, data are lacking from lactase deficient populations. This prospective cohort study assessed the prevalence of, and risk factors for, SLI in Chinese patients attending a gastroenterology clinic.

METHODS

Consecutive patients completed questionnaires to assess digestive health (Rome III), psychological state (HADS), life event stress (LES), food intake, and quality-of-life (SF-8). A representative sample completed genetic studies and hydrogen breath testing (HBT) at the clinically relevant dose of 20 g lactose.

KEY RESULTS

SLI was present in 411/910 (45%) clinic patients with functional abdominal symptoms. The genotype in all subjects was C/C-13910. A small number of novel SNPs in lactase promoter region were identified, including C/T-13908 which appeared to confer lactase persistence. Over half of the patients (54%) completed the 20 g lactose HBT with 58% (285/492) reporting typical symptoms. Positive and negative predictive values of SLI for abdominal symptoms during HBT were 60% and 44%, respectively. Psychological state and stress were not associated with SLI in clinic patients. SLI impacted on physical quality-of-life and was associated with reduced ingestion of dairy products, legumes, and dried fruit (p ≤ 0.05).

CONCLUSIONS & INFERENCES

In a lactase deficient population, approximately half of patients attending clinic with functional gastrointestinal symptoms reported intolerance to dairy products; however, SLI did not predict findings on 20 g lactose HBT. Independent of psychosocial factors, SLI impacted on quality-of-life and impacted on food choices with restrictions not limited to dairy products.

Development of biodegradable Zn-1X binary alloys with nutrient alloying elements Mg, Ca and Sr

Biodegradable metals have attracted considerable attentions in recent years. Besides the early launched biodegradable Mg and Fe metals, Zn, an essential element with osteogenic potential of human body, is regarded and studied as a new kind of potential biodegradable metal quite recently. Unfortunately, pure Zn is soft, brittle and has low mechanical strength in the practice, which needs further improvement in order to meet the clinical requirements. On the other hand, the widely used industrial Zn-based alloys usually contain biotoxic elements (for instance, ZA series contain toxic Al elements up to 40 wt.%), which subsequently bring up biosafety concerns. In the present work, novel Zn-1X binary alloys, with the addition of nutrition elements Mg, Ca and Sr were designed (cast, rolled and extruded Zn-1Mg, Zn-1Ca and Zn-1Sr). Their microstructure and mechanical property, degradation and in vitro and in vivo biocompatibility were studied systematically. The results demonstrated that the Zn-1X (Mg, Ca and Sr) alloys have profoundly modified the mechanical properties and biocompatibility of pure Zn. Zn-1X (Mg, Ca and Sr) alloys showed great potential for use in a new generation of biodegradable implants, opening up a new avenue in the area of biodegradable metals.

A study of the methodological and clinical validity of the combined lactulose hydrogen breath test with scintigraphic oro-cecal transit test for diagnosing small intestinal bacterial overgrowth in IBS patients

BACKGROUND

Small intestinal bacterial overgrowth (SIBO) may be a cause of irritable bowel syndrome (IBS); however, current investigations have important limitations. We aimed to identify clinically relevant diagnostic criteria for SIBO based on lactulose hydrogen breath test (LHBT) alone and combined with scintigraphic measurement of oro-cecal transit (SOCT).

METHODS

Results of LHBT/SOCT investigation from 89 IBS patients and 13 healthy volunteers were included in a systematic analysis of six published criteria for SIBO diagnosis. Clinical relevance of competing criteria was determined by assessing (i) prevalence of SIBO in IBS patients and healthy volunteers (ii) if SIBO diagnosis predicted improvement in IBS symptoms in a prospective, pilot therapeutic trial of a non-absorbable antibiotic (rifaximin 600 mg b.d.) in IBS patients.

KEY RESULTS

Reproducibility of SIBO diagnosis by combined LHBT/SOCT was near perfect. A ≥5 ppm H2 increase prior to appearance of cecal contrast was detected in more IBS patients than healthy volunteers (35/89 vs 1/13; p = 0.026), but not for other diagnostic criteria. IBS patients with SIBO, compared to those without SIBO, reported significantly greater improvement in abdominal symptoms following rifaximin therapy (p < 0.002 overall IBS symptom severity). This improvement was most marked in D-IBS patients in whom all symptoms improved, including stool frequency and consistency (all p < 0.004).

CONCLUSIONS & INFERENCES

Combined LHBT/SOCT testing using a H2 5 ppm cutoff may identify a subgroup of IBS patients with SIBO. Pilot data examining the clinical response to rifaximin suggest that this subset of IBS patients may benefit more than those with a normal test.

Lactose intolerance in irritable bowel syndrome patients with diarrhoea: the roles of anxiety, activation of the innate mucosal immune system and visceral sensitivity

BACKGROUND

Irritable bowel syndrome patients with diarrhoea (IBS-D) often report intolerance to milk; however, the mechanism underlying these symptoms is unknown.

AIM

To assess the role of psychological factors, immune activation and visceral sensitivity on the development of lactose intolerance (LI) in IBS-D patients.

METHODS

Fifty-five IBS-D patients and 18 healthy controls (HCs) with lactase deficiency underwent a 20-g lactose hydrogen breath test (LHBT). Patients were categorised as lactose malabsorption (LM; malabsorption only) or LI [malabsorption plus increase in total symptom score (TSS). Measurements included (i) psychological status; (ii) enteric biopsies with quantification of mast cells (MCs), T-lymphocytes and enterochromaffin cells; (iii) serum cytokines; (iv) rectal sensitivity before and after lactose ingestion.

RESULTS

LI was more prevalent in IBS-D patients than HCs [25/55 (46%) vs. 3/18 (17%), P = 0.029]. IBS-D patients with LI had (i) higher levels of anxiety than those with LM (P = 0.017) or HCs (P = 0.006); (ii) increased mucosal MCs compared with LM (P = 0.006) and HCs (P < 0.001); (iii) raised serum TNF-α compared with LM (P = 0.034) and HCs (P < 0.001) and (iv) increased rectal sensitivity after lactose ingestion compared with LM (P < 0.001) or HCs (P < 0.001). Severity of abdominal symptoms after lactose ingestion was associated with the increase in visceral sensitivity after lactose intake (r = 0.629, P < 0.001), MCs (r = 0.650, P < 0.001) and anxiety (r = 0.519, P < 0.001).

CONCLUSIONS

IBS-D patients with lactose intolerence are characterised by anxiety, mucosal immune activation and increased visceral sensitivity after lactose ingestion. The presence of these biomarkers may indicate an IBS phenotype that responds to dietary therapy and/or mast cell stabilisers.

Anti-tumour necrosis factor therapy enhances mucosal healing through down-regulation of interleukin-21 expression and T helper type 17 cell infiltration in Crohn's disease

Anti-tumour necrosis factor (TNF) monoclonal antibody (mAb) (infliximab, IFX) has been shown to be highly effective in the management of Crohn's disease (CD). Herein we investigated the potential role of IFX in inducing clinical remission and regulating interleukin (IL)-21 expression and T helper type 17 (Th17) cell infiltration in the intestinal mucosa of CD patients. Twenty-six CD patients were treated with IFX at weeks 0, 2 and 6. Clinical response, mucosal healing, serum C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) were evaluated at week 10 after IFX administration. Expression of IL-21, IL-17A and retinoic acid-related orphan receptor C (RORC) in intestinal mucosa were analysed by quantitative real-time polymerase chain reaction (PCR) and immunohistochemistry. Peripheral blood and lamina propria CD4(+) T cells were stimulated with anti-CD3 and anti-CD28 mAbs in the presence of IFX. Cytokine profiles and RORC were determined with enzyme-linked immunosorbent assay (ELISA) and real-time PCR. IL-21 and Th17 cells were found to be expressed highly in inflamed mucosa of active CD patients compared with healthy controls. Ten weeks after IFX infusion, CD activity index, ESR, CRP and intestinal mucosal healing were improved markedly in CD patients, and IL-21 expression and Th17 cell infiltration were decreased significantly compared with those before IFX therapy. In-vitro study demonstrated that IFX treatment could suppress IL-21, IL-17A and RORC expression in cultured CD biopsies. Moreover, IFX was also observed to down-regulate markedly IL-17A, IL-21 and RORC expression by CD CD4(+) T cells. IFX is highly effective in inducing clinical remission and promoting intestinal mucosal healing in CD patients through down-regulation of IL-21 expression and Th17 cell infiltration in intestinal mucosa.

Pennogenin tetraglycoside induces rat myometrial contraction and MLC20 phosphorylation via PLC-IP(3) and RhoA/Rho kinase signaling pathways

BACKGROUND

Total steroidal saponins extracted from the rhizome of Paris polyphylla Sm. var. yunnanensis (TSSPs) have been widely used in China for the treatment of abnormal uterine bleeding. We previously studied the main active constituents of TSSPs and their structure-activity relationships with respect to rat myometrial contractions. Tg (pennogenin tetraglycoside) was identified as one of the active ingredients in TSSPs able to induce rat myometrial contractions. However, the mechanisms underlying the pharmacological actions on uterine activity have not been described clearly.

METHODS

Here Tg was screened for effects on contractile activity in isolated uterine strips from estrogen-primed rats and on MLC20 phosphorylation and related signaling pathways in cultured rat myometrial cells as determined by Western blot. Intracellular calcium ([Ca(2+)](i)) was monitored under a confocal microscope using Fluo-4 AM-loaded myometrial cells.

RESULTS

Tg dose-dependently stimulated rat myometrial contractions as well as MLC20 phosphorylation in vitro, which could be completely suppressed by an inhibitor of myosin light chain kinase (MLCK). Use of Ca(2+) channel blockers and kinase inhibitors demonstrated that Tg-induced myometrial contractions are mediated by activation of the phospholipase C (PLC)-inositol triphosphate (IP3) signaling pathway, resulting in increased MLC20 phosphorylation. Furthermore, Y27632, a specific inhibitor of Rho kinase (ROK), notably suppressed Tg-stimulated myometrial contractions and decreased MLC20 phosphorylation.

CONCLUSIONS

These data provide evidence that rat myometrial contractility induced by Tg results from enhanced MLC20 phosphorylation, while both PLC-IP3 and RhoA/ROK signaling pathways mediate the process. These mechanisms may be responsible for the therapeutic effects of TSSPs on abnormal uterine bleeding.

Lactose intolerance in patients with chronic functional diarrhoea: the role of small intestinal bacterial overgrowth

BACKGROUND

Many studies report a high prevalence of lactose intolerance in patients with functional, gastrointestinal disease.

AIM

To evaluate the role of small intestinal bacterial overgrowth (SIBO) in condition of lactose intolerance and the mechanism by which SIBO may impact lactose tolerance in affected patients.

METHODS

Consecutive out-patients with chronic functional diarrhoea (CFD) and healthy controls underwent a validated 20 g lactose hydrogen breath test (HBT). Patients completed also a 10 g lactulose HBT with concurrent assessment of small bowel transit by scintigraphy.

RESULTS

Lactose malabsorption was present in 27/31 (87%) patients with CFD and 29/32 (91%) healthy controls (P = 0.708). From the patient group 14/27 (52%) had lactose intolerance and 13/27 (48%) experienced no symptoms (lactose malabsorption controls). Only 5 (17%) healthy controls reported symptoms (P < 0.01). The oro-caecal transit time was similar between patient groups with or without symptoms (P = 0.969). SIBO was present in 11 (41%) subjects and was more prevalent in lactose intolerance than in lactose malabsorption [9/14 (64%) vs. 2/13 (15%), P = 0.018]. Symptom severity was similar in lactose intolerance patients with and without SIBO (P = 0.344).

CONCLUSIONS

Small intestinal bacterial overgrowth increases the likelihood of lactose intolerance in patients with CFD as a direct result of lactose fermentation in the small intestine, independent of oro-caecal transit time and visceral sensitivity.

Distribution and enumeration of attractors in probabilistic Boolean networks

Many mathematical models for gene regulatory networks have been proposed. In this study, the authors study attractors in probabilistic Boolean networks (PBNs). They study the expected number of singleton attractors in a PBN and show that it is (2 - (1/2)(L-1))(n), where n is the number of nodes in a PBN and L is the number of Boolean functions assigned to each node. In the case of L=2, this number is simplified into 1.5(n). It is an interesting result because it is known that the expected number of singleton attractors in a Boolean network (BN) is 1. Then, we present algorithms for identifying singleton and small attractors and perform both theoretical and computational analyses on their average case time complexities. For example, the average case time complexities for identifying singleton attractors of a PBN with L=2 and L=3 are O(1.601(n)) and O(1.763(n)), respectively. The results of computational experiments suggest that these algorithms are much more efficient than the naive algorithm that examines all possible 2(n) states.

Prevalence of irritable bowel syndrome among undergraduates in Southeast China

BACKGROUND

There is a wide range in reported prevalence of irritable bowel syndrome worldwide. From the data appeared recently in medical literatures in China, it seems that the incidence of irritable bowel syndrome in young adults is not dissimilar to the one in the Western countries.

AIMS

To explore the prevalence and epidemiological variations of irritable bowel syndrome in an undergraduate student population in Southeast China on the basis of the Rome II and Rome III criteria.

METHODS

All the undergraduate student participants were administered self-report diagnostic measures for irritable bowel syndrome.

RESULTS

The sex-adjusted prevalence rate of irritable bowel syndrome was 4.7% (Rome II) and 10.4% (Rome III), respectively. When we combined irritable bowel syndrome mixed and irritable bowel syndrome unsubtyped in the Rome III subgroups into one group considering the counterpart in the Rome II subgroups was alternative irritable bowel syndrome, the agreement between the two ways to subdivide these 54 patients who were identified with irritable bowel syndrome by both the two criteria was 81%, with a kappa value of 0.67. By the Rome III criteria, we found a female predominance which was especially attributed to the subtypes of irritable bowel syndrome with constipation and unsubtyped.

CONCLUSIONS

Our study suggests that, in young adults in Southeast China, changing diagnostic criteria for irritable bowel syndrome from Rome II to Rome III may affect women more than men on not only the overall prevalence rate but also the sex-difference present or not, especially in irritable bowel syndrome with constipation and irritable bowel syndrome unsubtyped subgroups.

G1 phase cell cycle arrest induced by SARS-CoV 3a protein via the cyclin D3/pRb pathway

SARS-CoV 3a is a structural protein, mainly localizing to Golgi apparatus and co-localizing with SARS-CoV M in co-transfected cells. Here we observed that transient expression of 3a inhibited cell growth and prevented 5-bromodeoxyuridine incorporation, suggesting that 3a deregulated cell cycle progression. Cell cycle analysis demonstrated that 3a expression was associated with blockage of cell cycle progression at G1 phase in HEK 293, COS-7, and Vero cells 24-60 h after transfection. Mutation analysis of 3a revealed that C-terminal region (176 aa approximately 274 aa), including a potential calcium ATPase motif, was essential for induction of cell cycle arrest. Topological analysis showed that 3a predominantly located in Golgi apparatus, with its N-terminus residing in the lumen (Nlum) and C-terminus in the cytosol (Ccyt). Analyzing the cellular proteins involving in regulation of cell cycle progression, we demonstrated that 3a expression was correlated with a significant reduction of cyclin D3 level and phosphorylation of retinoblastoma (Rb) protein at Ser-795 and Ser-809/811, not with the expression of cyclin D1, D2, cdk4, and cdk6 in 293 cells. Increases in p53 phosphorylation on Ser-15 were observed in both SARS-CoV M and 3a transfected cells, suggesting that it might not correlate with the 3a-induced G0/G1 phase arrest. The reduction of cyclin D3 level and phosphorylation of Rb were further confirmed in SARS-CoV infected Vero cells. These results indicate that SARS-CoV 3a protein, through limiting the expression of cyclin D3, may inhibit Rb phosphorylation, which in turn leads to a block in the G1 phase of the cell cycle and an inhibition of cell proliferation.

Expression and Characterization of EarthwormEisenia foetidaLumbrokinase‐3 inPichia pastoris

Lumbrokinase-3 (LK-3, AY438622), first cloned from the earthworm Eisenia foetida in our laboratory, is a component of earthworm fibrinolytic enzymes. In this study, cDNA encoding the LK-3 gene was sub-cloned into yeast pPIC9K expression vector and transformed into the Pichia pastoris GS115 cells by electroporation. High level expression of LK-3 in yeast cells was confirmed with a different induction time. The activity of expressed LK-3 was observed in fibrin plates. In addition, the expressed LK-3 protein could dissolve fibrinogen and bovine serum albumin. The use of this system for the high level production of biological protein is implicated from this study.

Mitochondrial location of severe acute respiratory syndrome coronavirus 3b protein

Severe acute respiratory syndrome-associated coronavirus (SARS-CoV), a distant member of the Group 2 coronaviruses, has recently been identified as the etiological agent of severe acute respiratory syndrome (SARS). The genome of SARS-CoV contains four structural genes that are homologous to genes found in other coronaviruses, as well as six subgroup-specific open reading frames (ORFs). ORF3 encodes a predicted 154-amino-acid protein that lacks similarity to any known protein, and is designated 3b in this article. We reported previously that SARS-CoV 3b is predominantly localized in the nucleolus, and induces G0/G1 arrest and apoptosis in transfected cells. In this study, we show that SARS-CoV 3b fused with EGFP at its N- or C- terminus co-localized with a mitochondria-specific marker in some transfected cells. Mutation analysis of SARS-CoV 3b revealed that the domain spanning amino acids 80 to 138 was essential for its mitochondria localization. These results provide new directions for studies of the role of SARS-CoV 3b protein in SARS pathogenesis.

Interaction between Snapin and G-CSF receptor

Granulocyte colony-stimulating factor (G-CSF) is the major cytokine involved in the control of neutrophil development. G-CSF activates the special receptor, the G-CSF receptor (GCSF-R), which subsequently triggers multiple signaling events. To obtain more interactive molecules with GCSF-R and to further understand the cellular signaling mechanism of GCSF-R, yeast two-hybrid system was used to screen a mouse liver library. Here, the interaction of GCSF-R and Snapin was found by yeast two-hybrid experiment, and the interaction of the two proteins was further confirmed by GST pull-down experiment, mammalian two-hybrid experiment and co-immunoprecipitation study. Moreover, the immuno-fluorescence assay was shown that the two proteins of GCSF-R with Snapin were co-localized in the cytoplasm and plasma membrane. The region of C-terminal GCSF-R between box2 and box3, including the residue Tyr703, was responsible for the interaction with Snapin. These data suggested that Snapin is a new interactive protein of GCSF-R.

Macrophage migration inhibitory factor interacts with HBx and inhibits its apoptotic activity

HBx, a transcriptional transactivating protein of hepatitis B virus (HBV), is required for viral infection and has been implicated in virus-mediated liver oncogenesis. However, the precise molecular mechanism remains largely elusive. We used the yeast two-hybrid system to identify that HBx interacts with MIF directly. Macrophage migration inhibitory factor (MIF) is implicated in the regulation of inflammation, cell growth, and even tumor formation. The interaction between HBx and MIF was verified with co-immunoprecipitation, GST pull-down, and cellular colocalization. The expression of MIF was up-regulated in HBV particle producing cell 2.2.15 compared with HepG2 cell. Both HBx and MIF cause HepG2 cell G(0)/G(1) phase arrest, proliferation inhibition, and apoptosis. However, MIF can counteract the apoptotic effect of HBx. These results may provide evidence to explain the link between HBV infection and hepatocellular carcinoma.

Nucleolar localization of non-structural protein 3b, a protein specifically encoded by the severe acute respiratory syndrome coronavirus

The open reading frame 3 (ORF3) of the severe acute respiratory syndrome coronavirus (SARS-CoV) genome encodes a predicted 154-amino acid protein, which lacks similarities to any known protein, and is named 3b. In this study, it was shown that 3b protein was predominately localized to nucleus with EGFP tag at its N- or C-terminus. The localization patterns were similar in different transfected cells. Immuno-fluorescence assay revealed that 3b protein was co-localized well with C23 in nucleolus. C23, B23 and fibrillarin all are important nucleolar proteins, which localize in the region of the nucleolus. Co-transfection of p3b-EGFP with pC23-DsRed, pB23-DsRed and pfibrillarin-DsRed further confirmed 3b's nucleolus localization. With construction of serial truncated mutants of 3b, a region (residues 134-154 aa) responsible for nucleolar localization was determinated in 3b protein. These results provide a new insight for further functional studies of SARS-CoV 3b protein.

SARS coronavirus 7a protein blocks cell cycle progression at G0/G1 phase via the cyclin D3/pRb pathway

The genome of severe acute respiratory syndrome-associated coronavirus (SARS-CoV) contains four structural genes that are homologous to genes found in other coronaviruses, and also contains six subgroup-specific open reading frames (ORFs). Expression of one of these subgroup-specific genes, ORF7a, resulted in apoptosis via a caspase-dependent pathway. Here, we observed that transient expression of ORF7a protein fused with myc or GFP tags at its N or C terminus inhibited cell growth and prevented BrdU incorporation in different cultural cells, suggesting that ORF7a expression may regulate cell cycle progression. Analysis by flow cytometry demonstrated that ORF7a expression was associated with blockage of cell cycle progression at G0/G1 phase in HEK 293 cells after 24 to 60 h post-transfection. Similar results were observed in COS-7 and Vero cells. Mutation analysis of ORF7a revealed that the domain spanning aa 44–82 of 7a protein was essential for its cytoplasmic localization and for induction of the cell cycle arrest. After analyzing the cellular proteins involving in regulation of cell cycle progression, we demonstrated that ORF7a expression was correlated with a significant reduction of cyclin D3 level of mRNA transcription and expression, and phosphorylation of retinoblastoma (Rb) protein at ser795 and ser809/811, not with the expression of cyclin D1, D2, cdk4 and cdk6 in HEK 293 cells. These results suggest that the insufficient expression of cyclin D3 may cause a decreased activity of cyclin D/cdk4/6, resulting in the inhibition of Rb phosphorylation. Accumulation of hypo- or non-phosphorylated pRb thus prevents cell cycle progression at G0/G1 phase.

G0/G1 arrest and apoptosis induced by SARS-CoV 3b protein in transfected cells

Severe Acute Respiratory Syndrome coronavirus (SARS-CoV), cause of the life-threatening atypical pneumonia, infects many organs, such as lung, liver and immune organ, and induces parenchyma cells apoptosis and necrosis. The genome of SARS-CoV, not closely related to any of the previously characterized coronavirus, encodes replicase and four major structural proteins and a number of non-structural proteins. Published studies suggest that some non-structural proteins may play important roles in the replication, virulence and pathogenesis of viruses. Among the potential SARS-CoV non-structural proteins, 3b protein (ORF4) is predicted encoding 154 amino acids, lacking significant similarities to any known proteins. Till now, there is no report about the function of 3b protein. In this study, 3b gene was linked with the EGFP tag at the C- terminus. Through cell cycle analysis, it was found that over-expression of 3b-EGFP protein in Vero, 293 and COS-7 cells could induce cell cycle arrest at G0/G1 phase, and that especially in COS-7 cells, expression of 3b-EGFP was able to induce the increase of sub-G1 phase from 24 h after transfection, which was most obvious at 48 h. The apoptosis induction of 3b fusion protein in COS-7 cells was further confirmed by double cell labeling with 7-AAD and Annexin V, the function of 3b protein inducing cell G0/G1 arrest and apoptosis may provide a new insight for further study on the mechanism of SARS pathogenesis.

G0/G1 arrest and apoptosis induced by SARS-CoV 3b protein in transfected cells

Severe Acute Respiratory Syndrome coronavirus (SARS-CoV), cause of the life-threatening atypical pneumonia, infects many organs, such as lung, liver and immune organ, and induces parenchyma cells apoptosis and necrosis. The genome of SARS-CoV, not closely related to any of the previously characterized coronavirus, encodes replicase and four major structural proteins and a number of non-structural proteins. Published studies suggest that some non-structural proteins may play important roles in the replication, virulence and pathogenesis of viruses. Among the potential SARS-CoV non-structural proteins, 3b protein (ORF4) is predicted encoding 154 amino acids, lacking significant similarities to any known proteins. Till now, there is no report about the function of 3b protein. In this study, 3b gene was linked with the EGFP tag at the C- terminus. Through cell cycle analysis, it was found that over-expression of 3b-EGFP protein in Vero, 293 and COS-7 cells could induce cell cycle arrest at G0/G1 phase, and that especially in COS-7 cells, expression of 3b-EGFP was able to induce the increase of sub-G1 phase from 24 h after transfection, which was most obvious at 48 h. The apoptosis induction of 3b fusion protein in COS-7 cells was further confirmed by double cell labeling with 7-AAD and Annexin V, the function of 3b protein inducing cell G0/G1 arrest and apoptosis may provide a new insight for further study on the mechanism of SARS pathogenesis.

Subcellular localization and membrane association of SARS-CoV 3a protein

SARS-CoV 3a protein was a unique protein of SARS coronavirus (SARS-CoV), which was identified in SARS-CoV infected cells and SARS patients’ specimen. Recent studies revealed that 3a could interact specifically with many SARS-CoV structural proteins, such as M, E and S protein. Expressed 3a protein was reported to localize to Golgi complex in SARS-CoV infected cells. In this study, it was shown that 3a protein was mainly located in Golgi apparatus with different tags at N- or C-terminus. The localization pattern was similar in different transfected cells. With the assay of truncated 3a protein, it was shown that 3a might contain three transmembrane regions, and the second or third region was properly responsible for Golgi localization. By ultra-centrifugation experiment with different extraction buffers, it was confirmed that 3a was an integral membrane protein and embedded in the phospholipid bilayer. Immunofluorescence assay indicated that 3a was co-localized with M protein in Golgi complex in co-transfected cells. These results provide a new insight for further study of the 3a protein on the pathogenesis of SARS-CoV.

Early upregulation of T cell IL-10 production plays an important role in oral tolerance induction

Early in oral tolerance induction, IL-10-producing CD4(+) T cells were increased, and adoptive transfer of IL-10-deficient CD4(+) T cells failed induction of oral tolerance, suggesting a key role of IL-10 production in such a process.

Regulation of LIP level and ROS formation through interaction of H-ferritin with G-CSF receptor

A variety of hematopoietic factors including granulocyte macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor (G-CSF), interleukin 3 (IL-3) and thrombopoietin (TPO) induce a rapid increase of intracellular reactive oxygen species (ROS). ROS induces the activation of many signaling molecules, including Shc, Lck, syk, PKC, MAPK, STAT3, through inhibition of protein phosphatase. Each growth factor has a specific cell-surface receptor, which activates both unique and shared signal transduction pathways. The processes of signal transduction linking cell-surface receptor to the formation of intracellular ROS have not been elucidated fully. Ferritins are composed of two subunit types, H and L, and made of 24 subunits that sequester up to 4500 atoms of iron. When the stored iron atoms are released from H-ferritin, through iron-catalyzed reaction, they have the capacity to promote the formation of ROS. Here, the interaction of G-CSFR and H-ferritin was confirmed by yeast two-hybrid screen, mammalian two-hybrid assays, glutathione-S-transferase (GST) pull-down experiments and immunoprecipitation studies in vitro and in vivo. Additional immunofluorescence assay showed that the two proteins colocalized along the plasma membrane and partly in the cytoplasm. The binding site for H-ferritin was demonstrated to locate to the box3 motif on the C-terminal region of granulocyte colony-stimulating factor receptor (G-CSFR). Furthermore, we found the interaction of full-length G-CSFR with H-ferritin was dissociated at 30 minutes after G-CSF induction and then began to assemble at 45 minutes. The labile iron pool (LIP) is a pool of redox-active iron complexes, which is regulated tightly by the expression of H-ferritin. Experiments showed that the level of LIP increased significantly at 30 minutes after G-CSF stimulation and intracellular ROS formation changed in a pattern similar to LIP response to G-CSF in bone-marrow hematopoietic cells. G-CSF-induced changes in the level of LIP and ROS formation could be blocked by pretreatment with iron chelators that repressed the expression of H-ferritin. In addition, the phosphorylation of STAT3 induced by G-CSF was decreased in iron chelator-treated hematopoietic cells. These data suggested that LIP may be released from the dissociated H-ferritin, and then induce intracellular ROS formation in the bone-marrow hematopoietic cells. ROS, acting as a second messenger, might take part in G-CSF receptor signal transduction. So, here, a new G-CSFR-H-ferritin-LIP-ROS pathway is proposed for regulation of intracellular ROS formation in bone-marrow hematopoietic cells.

Immunostimulatory activity of CpG oligonucleotides containing non-ionic methylphosphonate linkages

Bacterial DNA and synthetic oligodeoxynucleotides containing unmethylated CpG-motifs in a particular sequence context activate vertebrate immune cells. We examined the significance of negatively charged internucleoside linkages in the flanking sequences 5' and 3' to the CpG-motif on immunostimulatory activity. Cell proliferation and secretion of IL-12 and IL-6 in mouse spleen cell cultures, and spleen weights of mice increased significantly when a non-ionic linkage was placed at least four or more internucleoside linkages away from the CpG-motif in the 5'-flanking sequence. When the non-ionic linkage was placed closer than three internucleoside linkages in the 5'-flanking sequence to the CpG-motif, immunostimulatory activity was suppressed compared with that observed with the unmodified parent oligo. In general, the placement of non-ionic linkage in the 3'-flanking sequence to the CpG-motif either did not affect or slightly increased immunostimulatory activity compared with the parent oligo. These results have significance in understanding CpG oligonucleotide-receptor interactions and the development of potent immunomodulatory agents.

Modulation of immunostimulatory activity of CpG oligonucleotides by site-specific deletion of nucleobases

The effect of nucleobase deletion in the 3'- or the 5'-flanking sequence to a CpG-motif on immunostimulatory activity of CpG-containing oligonucleotides was examined by cell proliferation, secretion of IL-12 and IL-6 in mouse spleen cell cultures, and by spleen enlargement in mice. Deletion of one or two nucleobases in the 3'-flanking sequence to a CpG-motif at certain positions did not affect immunostimulatory activity, while similar deletions in the 5'-flanking sequence increased immunostimulatory activity compared with the parent oligo.

Immuno-bacterial homeostasis in the gut: new insights into an old enigma

The intestinal mucosa is the interface between the immune system and the massive antigenic load represented by the commensal enteric bacteria. These commensal bacteria drive the development of the mucosal immune system, and in turn most of the lymphocytes in the intestinal mucosa appear to be specific for enteric bacteria antigens. Proper regulation of the responses of these anti-bacterial lymphocytes are extremely important because T cell effectors reactive to enteric bacterial antigens have been shown to cause chronic intestinal inflammation in an adoptive transfer system. The cells and molecules important in regulating mucosal immune response are now being identified. Insights into the mechanisms of mucosal regulation have come from a number of genetically manipulated mouse strains which develop inflammatory bowel disease in response to the enteric bacterial flora. CD4(+)T cells with regulatory function in the mucosa are being identified; other cell types such as CD8(+)T cells. NK cells, and B cells may also have a role in mucosal immune regulation. A model for T cell-immune homeostasis in the intestinal mucosa is presented.

Effects of cholera toxin on macrophage production of co-stimulatory cytokines

Cholera toxin (CT), the enterotoxin of Vibrio cholerae, is a potent mucosal and systemic immunogen and adjuvant. The precise mechanism of the adjuvanticity of CT is poorly understood. Our previous work has showed that CT up-regulates B7.2, but not B7.1 expression on macrophages, and thus increases their co-stimulatory activity. In the current study, the effects of CT on macrophage co-stimulatory cytokine production were investigated. Bone marrow macrophages were generated by culturing bone marrow cells with macrophage colony-stimulating factor. CT treatment increased endotoxin-stimulated macrophage IL-10, IL-6, and IL-1beta production, whereas it decreased IL-12, TNF-alpha and nitric oxide production. Antibody blocking experiments showed that CT inhibition of IL-12 and TNF-alpha production was mediated by increased IL-10 production, in that addition of anti-IL-10 monoclonal antibody abrogated CT inhibition. The decrease in nitric oxide production was in turn secondary to inhibition of TNF-alpha production. Taken together, our study demonstrated that CT has differential effects on various macrophage co-stimulatory cytokines, effects that are likely to contribute to its adjuvanticity.

Heritable susceptibility for colitis in mice induced by IL-10 deficiency

Severity of inflammatory bowel disease in IL-10 gene-targeted mice is in part determined by genetic background. In the current study, a targeted IL-10 gene was transferred into the C3H/HeJBir substrain, known to exhibit high T-cell and B-cell responses to enteric flora, and to be highly sensitive to colitigenic stress. IL-10-deficient C3H/HeJBir mice developed early onset colitis in contrast to IL-10-deficient C57BL/6J congenic mice. Histopathologic analysis of disease in C3H/HeJBir.Il10-/- and C57BL/6J.Il10-/- mice showed significant differences at all ages studied. Hybrids of these congenic strains (F1.Il10-/-) were produced to study the mode of inheritance as well as subphenotypes that correlated with histopathology. Lesions in F1 mice were intermediate between parental strains. C3H-contributed subphenotypes that correlated best with histopathology were peripheral blood granulocyte percentage, serum amyloid A concentration, spleen weight/body weight ratio, and mesenteric lymph node weight/ body weight ratio. Neither enhanced humoral immunity (secretory IgA, anti-Escherichia coli cellular membrane Ig) characteristic of C3H/HeJBir, nor T-cell percentages in peripheral blood correlated as well. This study represents a necessary step in elucidating murine genetic modifiers controlling colitis sensitivity.

Colitis induced by enteric bacterial antigen-specific CD4+ T cells requires CD40-CD40 ligand interactions for a sustained increase in mucosal IL-12

C3H/HeJBir is a mouse substrain that is highly susceptible to colitis. Their CD4+ T cells react to Ags of the commensal enteric bacteria, and the latter can mediate colitis when activated by these Ags and transferred to histocompatible scid recipients. In this study, multiple long-term C3H/HeJBir CD4+ T cell (Bir) lines reactive to commensal enteric bacterial Ags have been generated. All these were Ag specific, pauciclonal, and Th1 predominant; most induced colitis uniformly after transfer to scid recipients. Lesions were focal and marked by increased expression of IL-12p40 and IFN-gamma mRNA and protein. Pathogenic Bir T cell lines expressed CD40 ligand (CD40L) when cultured with Ag-pulsed APCs in vitro. Production of IL-12 was also increased in such cultures, an effect that was Ag- and T cell-dependent and required costimulation by CD40, but not by B7. The two Bir T cell lines that did not induce lesions after transfer failed to significantly express CD40L or increase IL-12 when cultured with Ag-pulsed APCs. Administration of anti-CD40L blocked disease expression induced by pathogenic T cells. We conclude that interactions in the colon mucosa between CD40L-expressing Bir Th1 cells with APCs endogenously loaded with commensal bacterial Ags are critical for sustained increases in local IL-12 production and progression to colitis.

Inhibiting protein-protein interactions: a model for antagonist design

Protein-protein interactions (PPI) are a ubiquitous mode of transmitting signals in cells and tissues. We are testing a stepwise, generic, structure-driven approach for finding low molecular weight inhibitors of protein-protein interactions. The approach requires development of a high-affinity, single chain antibody directed specifically against the interaction surface of one of the proteins to obtain structural information on the interface. To this end, we developed a single chain antibody (sc1E3) against hIL-1beta that exhibited the equivalent affinity of the soluble IL-1 receptor type I (sIL-1R) for hIL-1beta and competitively blocked the sIL-1R from binding to the cytokine. The antibody proved to be more specific for hIL-1beta than the sIL-1R in that it failed to bind to either murine IL-1beta or human/murine IL-1alpha proteins. Additionally, failure of sc1E3 to bind to several hIL-1beta mutant proteins, altered at receptor site B, indicated that the antibody interacted preferentially with this site. This, coupled with other surface plasmon resonance and isothermal titration calorimetry measurements, shows that sc1E3 can achieve comparable affinity of binding hIL-1beta as the receptor through interactions at a smaller interface. This stable single chain antibody based heterodimer has simplified the complexity of the IL-1/IL-1R PPI system and will facilitate the design of the low molecular weight inhibitors of this interaction.

The C3H/HeJBir mouse model: a high susceptibility phenotype for colitis

C3H/HeJBir is a substrain of C3H/HeJ mice that was generated by selective breeding for the phenotype of spontaneous colitis. These mice show increased B cell and T cell reactivity to antigens of the enteric bacterial flora. CD4+ T cells from this strain cause colitis, when activated by enteric bacterial antigens and transferred to histocompatible severe combined immunodeficient recipients. The expression of the disease phenotype of spontaneous colitis is greatly influenced by housing conditions and probably requires an immunostimulatory enteric flora. This strain seems to carry multiple susceptibility genes for colitis as does the parental C3H/HeJ strain; the genes involved are being mapped. This strain represents a high susceptibility phenotype for colitis that is providing insight into the interactions among immune, environmental and genetic factors that can result in IBD.

Extended half-life and elevated steady-state level of a single-chain Fv intrabody are critical for specific intracellular retargeting of its antigen, caspase-7

8 h) and high steady-state levels of protein accumulation, while the H2 intrabodies had a half-life of 2 h and less protein at steady state. These results suggest that the choice of sFv as an intrabody depends critically on the intracellular sFv protein having an extended half-life and elevated steady-state level. Thus, extended half-life must be considered together with sFv antibody specificity and affinity when choosing an optimal sFv intrabody for functional studies of cellular proteins.