IL-4, IL-10 and IL-13 down-regulate monocyte-chemoattracting protein-1 (MCP-1) production in activated intestinal epithelial cells

IL-13 protects from Clostridioides difficile colitis

OBJECTIVES

Clostridioides difficile infection (CDI) is the leading hospital-acquired infection in North America. We have previously discovered that antibiotic disruption of the gut microbiota decreases intestinal IL-33 and IL-25 and increases susceptibility to CDI. We further found that IL-33 promotes protection through type 2 Innate Lymphoid Cells (ILC2s), which produce IL-13. However, the contribution of IL-13 to disease has never been explored.

METHODS

We used a validated model of CDI in mice, in which we neutralized via blocking antibodies, or administered recombinant protein, IL-13 to assess the role of this cytokine during infection using weight and clinical scores. Fluorescent activated cell sorting (FACS) was used to characterize myeloid cell population changes in response to IL-13 manipulation.

RESULTS

We found that administration of IL-13 protected, and anti-IL-13 exacerbated CDI. Additionally, we observed alterations to the monocyte/macrophage cells following neutralization of IL-13 as early as day three post infection. We also observed elevated accumulation of myeloid cells by day four post-infection following IL-13 neutralization. Neutralization of the decoy receptor, IL-13Rα2, resulted in protection from disease, likely through increased available endogenous IL-13.

CONCLUSIONS

Our data highlight the protective role of IL-13 in protecting from more severe CDI and the association of poor responses with a dysregulated monocyte-macrophage compartment. These results increase our understanding of type 2 immunity in CDI and may have implications for treating disease in patients.

Characterization of differences in immune responses during bolus and continuous infusion endotoxin challenges using mathematical modelling

Endotoxin administration is commonly used to study the inflammatory response, and though traditionally given as a bolus injection, it can be administered as a continuous infusion over multiple hours. Several studies hypothesize that the latter better represents the prolonged and pronounced inflammation observed in conditions like sepsis. Yet very few experimental studies have administered endotoxin using both strategies, leaving significant gaps in determining the underlying mechanisms responsible for their differing immune responses. We used mathematical modelling to analyse cytokine data from two studies administering a 2 ng kg-1 dose of endotoxin, one as a bolus and the other as a continuous infusion over 4 h. Using our model, we simulated the dynamics of mean and subject-specific cytokine responses as well as the response to long-term endotoxin administration. Cytokine measurements revealed that the bolus injection led to significantly higher peaks for interleukin (IL)-8, while IL-10 reaches higher peaks during continuous administration. Moreover, the peak timing of all measured cytokines occurred later with continuous infusion. We identified three model parameters that significantly differed between the two administration methods. Monocyte activation of IL-10 was greater during the continuous infusion, while tumour necrosis factor α $ {\alpha} $ and IL-8 recovery rates were faster for the bolus injection. This suggests that a continuous infusion elicits a stronger, longer-lasting systemic reaction through increased stimulation of monocyte anti-inflammatory mediator production and decreased recovery of pro-inflammatory catalysts. Furthermore, the continuous infusion model exhibited prolonged inflammation with recurrent peaks resolving within 2 days during long-term (20-32 h) endotoxin administration.

Mast cell-derived IL-10 protects intestinal barrier integrity during malaria in mice and regulates parasite transmission to Anopheles stephensi with a female-biased immune response

Malaria is strongly predisposed to bacteremia, which is associated with increased gastrointestinal permeability and a poor clinical prognosis. We previously identified mast cells (MCs) as mediators of intestinal permeability in malaria and described multiple cytokines that rise with parasitemia, including interleukin (IL)-10, which could protect the host from an inflammatory response and alter parasite transmission to Anopheles mosquitoes. Here, we used the Cre-loxP system and non-lethal Plasmodium yoelii yoelii 17XNL to study the roles of MC-derived IL-10 in malaria immunity and transmission. Our data suggest a sex-biased and local inflammatory response mediated by MC-derived IL-10, supported by early increased number and activation of MCs in females relative to males. Increased parasitemia in female MC IL-10 (-) mice was associated with increased ileal levels of chemokines and plasma myeloperoxidase (MPO). We also observed increased intestinal permeability in female and male MC IL-10 (-) mice relative to MC IL-10 (+) mice but no differences in blood bacterial 16S DNA levels. Transmission success of P. yoelii to A. stephensi was higher in female relative to male mice and from female and male MC IL-10 (-) mice relative to MC IL-10 (+) mice. These patterns were associated with increased plasma levels of pro-inflammatory cytokines in female MC IL-10 (-) mice and increased plasma levels of chemokines and markers of neutrophil activation in male MC IL-10 (-) mice. Overall, these data suggest that MC-derived IL-10 protects intestinal barrier integrity, regulates parasite transmission, and controls local and systemic host immune responses during malaria, with a female bias.

Molecular Pathogenesis of Human Immunodeficiency Virus-Associated Disease of Oropharyngeal Mucosal Epithelium

The oropharyngeal mucosal epithelia have a polarized organization, which is critical for maintaining a highly efficient barrier as well as innate immune functions. In human immunodeficiency virus (HIV)/acquired immune deficiency syndrome (AIDS) disease, the barrier and innate immune functions of the oral mucosa are impaired via a number of mechanisms. The goal of this review was to discuss the molecular mechanisms of HIV/AIDS-associated changes in the oropharyngeal mucosa and their role in promoting HIV transmission and disease pathogenesis, notably the development of opportunistic infections, including human cytomegalovirus, herpes simplex virus, and Epstein-Barr virus. In addition, the significance of adult and newborn/infant oral mucosa in HIV resistance and transmission was analyzed. HIV/AIDS-associated changes in the oropharyngeal mucosal epithelium and their role in promoting human papillomavirus-positive and negative neoplastic malignancy are also discussed.

Coprococcus eutactus, a Potent Probiotic, Alleviates Colitis via Acetate-Mediated IgA Response and Microbiota Restoration

Inflammatory bowel disease (IBD) is a complex disease characterized by relapsing episodes of inflammation of the colonic mucosa. Research into IBD suggests that this disease condition is caused by alterations in resident mucosal bacterial populations. Our previous study showed that Coprococcus was significantly elevated during the improvement of IBD. Human metagenome database GMrepo also indicates Coprococcus, in particular, Coprococcus eutactus (C. eutactus), which was negatively associated with IBD. The current study implied the alleviated effects and mechanisms of C. eutactus on dextran sodium sulfate-induced experimental colitis mice. Gavage with C. eutactus-ameliorated acute colitis, as evidenced, relieved weight loss, decreased concentrations of proinflammatory cytokines TNF-α, IL-1β, and IL-6, and increased anti-inflammatory factors, IL-4, IL-5, and IL-10. In addition, C. eutactus enhanced the maturation of goblet cells and the expressions of mucins and restored the expressions of tight junction proteins such as claudin-1, occludin, and ZO-1. As a short-chain fatty acid-producing bacterium, C. eutactus mainly generates acetic acid. Interestingly, not only high levels of secretory immunoglobulin A (SIgA) but also increased IgA-producing plasma cells were observed in colitis mice during the administration of C. eutactus. Importantly, our data demonstrated that colonic SIgA is specifically coated on pathogens of Enterobacteriaceae. Owing to the selective binding effect of SIgA on microorganisms, the microbial diversity in the intestinal lumen and mucosa of C. eutactus-treated colitis mice was significantly restored, and the microbiota structure was remodeled. These findings provide substantial insight that C. eutactus as a promising probiotic can ameliorate colitis. In conclusion, our findings may deliver a novel approach to the prevention and biotherapy of IBD.

Effects of Bifidobacterium with the Ability of 2'-Fucosyllactose Utilization on Intestinal Microecology of Mice

In breast milk, 2'-Fucosyllactose (2'FL) is the most abundant breast milk oligosaccharide and can selectively promote the proliferation of bifidobacteria. This study aimed to explore the effect of ifidobacterial with different utilization capacities of 2'FL on the intestinal microecology of mice. Furthermore, the effects of ifidobacterial with different 2'FL utilization capabilities on mice gut microbiota under the competitive pressure of 2'FL as a carbon source were explored. Compared with the control group, 2'FL, Bifidobacterium (B.) bifidum M130R01M51 + 2'FL, B. longum subsp. Longum CCFM752, and CCFM752 + 2'FL treatments significantly decreased the food intake. Moreover, the water intake, body weight, and fecal water content in all groups showed no significant difference compared with the control group. The combination of B. longum subsp. longum CCFM752 and 2'FL can significantly increase the levels of pro-inflammatory and anti-inflammatory factors. B. bifidum M130R01M51 and mixed strains combined with 2'FL significantly increased the contents of acetic acid and isobutyric acid. The results showed that B. bifidum M130R01M51, B. breve FHuNCS6M1, B. longum subsp. longum CCFM752, and B. longum subsp. infantis SDZC2M4 combined with 2'FL significantly increased the species richness of the gut microbiota. Moreover, B. longum subsp. longum CCFM752 and B. longum subsp. infantis SDZC2M4 significantly increased the abundance of Faecalibaculum and Bifidobacterium, respectively. In conclusion, exploring the impact on intestinal microecology can provide theoretical guidance for the development of personalized prebiotics for different bifidobacteria, which has the potential to improve the ecological imbalance of infant gut microbiota.

Polyphenols from foxtail millet bran ameliorate DSS-induced colitis by remodeling gut microbiome

INTRODUCTION

Polyphenols from plants possess the anti-inflammatory and gut microbiota modulated properties. Foxtail millet (Setaria italica L., FM) has potential medical and nutritional functions because of rich phenolic and other phytochemical components.

METHODS

Here, the study explored the effects of bound polyphenol of inner shell (BPIS) from FM bran on dextran sodium sulfate (DSS)-induced experimental colitis mice.

RESULTS

Results showed that BPIS administration effectively relieved the weight loss, decreased disease active index (DAI) scores, restrained the secretion of pro-inflammatory cytokines TNF-α, IL-6 and IL-1β, increased anti-inflammatory cytokines IL-10, IL-4, IL-5. BPIS prevented gut barrier damage by enhancing tight junction proteins Claudin1, ZO-1 and Occludin, increasing the number of goblet cells and facilitating the gene expressions of mucin family. In addition, BPIS restored the gut microbiota composition and increased the relative abundance of commensal bacteria such as Lachnospiraceae and Rikenellaceae and restrained the growth of S24-7 and Staphylococcaceae. Concentrations of short-chain-fatty acids (SCFAs) generated by gut microbiota were elevated in BPIS treated colitis mice.

CONCLUSION

These data suggest that BPIS effectively ameliorates DSS-induced colitis by preventing intestinal barrier damage and promoting gut microbiota community.

Effects of Glycyrrhiza Polysaccharides on Chickens' Intestinal Health and Homeostasis

The overuse of antibiotics in poultry farming causes the accumulation of drug residue in animals' bodies and the occurrence of antibiotic-resistant bacteria, which not only compromise animals' health but ultimately endanger human health. Thus, there is an urgent need for a novel poultry feed additive to substitute for excessive antibiotics. Glycyrrhiza polysaccharides (GPS) derived from Chinese licorice have shown promising immunomodulatory effects in previous studies. The present study investigated the pharmacological effects of GPS on poultry intestines to assess whether it can be used as a feed additive. The results show that GPS can increase production of sIgA, promote the secretion activity of goblet cells, alter the gut microbial composition and lead to changes in short-chain fatty acids. GPS also elevated both Th1 and Th2 immune responses by facilitating the expression of IL-2, IL-4, IL-1β, and IFN-γ while increasing the proportion of both CD4+ and CD8+ cells in the intestine. Moreover, the results of 16S rRNA gene sequencing showed that GPS could significantly change intestinal microbiota composition in the intestine, evidenced by the increased proportion of Bacteroides, Butyricicoccus and Eisenbergiella, as well as a decreased portion of Erysipelatoclostridium, leading to a healthier intestinal microbiota composition for the host. Taken together, it can be concluded that GPS is safe to use as a novel feed additive that can be used as an alternative to prophylactic antibiotics in poultry feeding.

COVID-19 pandemic: insights into molecular mechanisms leading to sex-based differences in patient outcomes

Recent epidemiological studies analysing sex-disaggregated patient data of coronavirus disease 2019 (COVID-19) across the world revealed a distinct sex bias in the disease morbidity as well as the mortality - both being higher for the men. Similar antecedents have been known for the previous viral infections, including from coronaviruses, such as severe acute respiratory syndrome (SARS) and middle-east respiratory syndrome (MERS). A sound understanding of molecular mechanisms leading to the biological sex bias in the survival outcomes of the patients in relation to COVID-19 will act as an essential requisite for developing a sex-differentiated approach for therapeutic management of this disease. Recent studies which have explored molecular mechanism(s) behind sex-based differences in COVID-19 pathogenesis are scarce; however, existing evidence, for other respiratory viral infections, viz. SARS, MERS and influenza, provides important clues in this regard. In attempt to consolidate the available knowledge on this issue, we conducted a systematic review of the existing empirical knowledge and recent experimental studies following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The qualitative analysis of the collected data unravelled multiple molecular mechanisms, such as evolutionary and genetic/epigenetic factors, sex-linkage of viral host cell entry receptor and immune response genes, sex hormone and gut microbiome-mediated immune-modulation, as the possible key reasons for the sex-based differences in patient outcomes in COVID-19.

The Production and Function of Endogenous Interleukin-10 in Intestinal Epithelial Cells and Gut Homeostasis

The healthy gut is achieved and maintained through a balanced relationship between the mucosal immune system, microbial communities resident in the lumen, and the intestinal epithelium. The intestinal epithelium plays an exceptionally important role in harmonizing the interaction between the host immunity and the luminal residents, as this selectively permeable barrier separates but also allows interchange between the 2 environments. Interleukin (IL)-10 has been well established to play an important role in maintaining gut homeostasis by imparting diverse effects on a variety of cell types in this relationship. In the intestine, the source and the target of IL-10 include leukocytes and epithelial cells. Given that both the epithelium and IL-10 are essential players in supporting homeostasis, we discuss the relationship between these 2 factors, focusing on epithelial sources of IL-10 and the effects of IL-10 on the intestinal epithelium. Insight into this relationship reveals an important aspect of the innate immune function of intestinal epithelial cells.

Lactose-Gated Mesoporous Silica Particles for Intestinal Controlled Delivery of Essential Oil Components: An In Vitro and In Vivo Study

Mesoporous silica microparticles functionalized with lactose for the specific release of essential oil components (EOCs) in the small intestine are presented. In vitro and in vivo intestinal models were applied to validate the microparticles (M41-EOC-L), in which the presence of lactase acts as the triggering stimulus for the controlled release of EOCs. Among the different microdevices prepared (containing thymol, eugenol and cinnamaldehyde), the one loaded with cinnamaldehyde showed the most significant Caco-2 cell viability reduction. On the other hand, interaction of the particles with enterocyte-like monolayers showed a reduction of EOCs permeability when protected into the designed microdevices. Then, a microdevice loaded with cinnamaldehyde was applied in the in vivo model of Wistar rat. The results showed a reduction in cinnamaldehyde plasma levels and an increase in its concentration in the lumen of the gastrointestinal tract (GIT). The absence of payload release in the stomach, the progressive release throughout the intestine and the prolonged stay of the payload in the GIT-lumen increased the bioavailability of the encapsulated compound at the site of the desired action. These innovative results, based on the specific intestinal controlled delivery, suggest that the M41-payload-L could be a potential hybrid microdevice for the protection and administration of bioactive molecules in the small intestine and colon.

Immunomodulatory and Antioxidative potentials of adipose-derived Mesenchymal stem cells isolated from breast versus abdominal tissue: a comparative study

BACKGROUND

Adipose-derived stem cells (ASCs) are considered ideal candidates for both research and cellular therapy due to ease of access, large yield, feasibility, and efficacy in preclinical and clinical studies. Unlike the subcutaneous abdominal fat depot, breast ASCs features are still not well recognized, limiting their possible therapeutic use. ASCs were found to exert immunomodulatory and antioxidative activities for maintaining homeostasis and functionality of diseased/damaged tissues. This study aims to investigate the immunomodulatory and antioxidative potentials of breast versus abdominal isolated ASCs to find out which anatomical site provides ASCs with better immunoregulatory and oxidative stress resistance capabilities.

METHODS

ASCs were isolated from abdominal and breast tissues. Gene expression analysis was conducted for a panel of immunomodulatory and antioxidative genes, as well as adipokines and proliferation genes. Flow cytometric analysis of a group of immunomodulatory surface proteins was also performed. Finally, the significantly expressed genes have undergone protein-protein interaction and functional enrichment in silico analyses.

RESULTS

Our results revealed similar morphological and phenotypic characteristics for both breast and abdominal ASCs. However, a significant elevation in the expression of two potent immunosuppressive genes, IL-10 and IDO as well as the expression of the multifaceted immunomodulatory adipokine, visfatin, was detected in breast versus abdominal ASCs. Moreover, a significant overexpression of the antioxidative genes, GPX1, SIRT5, and STAT3 and the proliferation marker, Ki67, was also observed in breast ASCs relative to abdominal ones. In silico analysis showed that both of the differentially upregulated immunomodulatory and antioxidative mediators integratively involved in multiple biological processes and pathways indicating their functional association.

CONCLUSION

Breast ASCs possess superior immunomodulatory and antioxidative capabilities over abdominal ASCs. Our findings shed light on the possible therapeutic applications of breast ASCs in immune-related and oxidative stress-associated diseases.

Maltotriose Conjugated Metal-Organic Frameworks for Selective Targeting and Photodynamic Therapy of Triple Negative Breast Cancer Cells and Tumor Associated Macrophages

Herein, we report a nano-MOF conjugated to maltotriose as a new DDS. MA-PCN-224-0.1Mn/0.9Zn showed its ability to target cancer and TAM. This novel MOF is an effective PDT agent and shows little dark toxicity, MA-PCN-224-0.1Mn/0.9Zn uptakes selectively into cancer cells. A well-suited size control methodology was used so that the nano-scaled MOFs may take advantage of the EPR effect. This development of a nano-scale MOF for PDT that is conjugated to a cancer targeting ligand represents a meaningful development for the use of MOFs as drug delivery systems.

Skim milk powder with high content of Maillard reaction products affect weight gain, organ development and intestinal inflammation in early life in rats

BACKGROUND

The intestinal tract is important for development of immune tolerance and disturbances are suggested to trigger autoimmune disorders. The aim of this study was to explore the effect of Maillard products in skim milk powder obtained after long storage, compared to fresh skim milk powder.

METHODS

Young rats were weaned onto a diet based on skim milk powder with high concentration of Maillard products (HM-SM, n = 18) or low (C-SM, n = 18) for one week or four weeks. Weekly body weight and feed consumption were noted. At the end, organ weights, intestinal histology, permeability and inflammatory cytokines were evaluated.

RESULTS

Rats fed with HM-SM had after one week, 15% less weight gain than controls, despite equal feed intake. After one week thymus and spleen were smaller, intestinal mucosa thickness was increased and acute inflammatory cytokines (IL-17, IL-1β, MCP-1) were elevated. After four weeks, cytokines associated with chronic intestinal inflammation (fractalkine, IP-10, leptin, LIX, MIP-2, RANTES and VEGF) were increased in rats fed with HM-SM compared to C-SM.

CONCLUSION

High content of Maillard products in stored milk powder caused an intestinal inflammation. Whether this is relevant for tolerance development and future autoimmune diseases remains to be explored.

Biotransformation and Biological Interaction of Graphene and Graphene Oxide during Simulated Oral Ingestion

The biotransformation and biological impact of few layer graphene (FLG) and graphene oxide (GO) are studied, following ingestion as exposure route. An in vitro digestion assay based on a standardized operating procedure (SOP) is exploited. The assay simulates the human ingestion of nanomaterials during their dynamic passage through the different environments of the gastrointestinal tract (salivary, gastric, intestinal). Physical-chemical changes of FLG and GO during digestion are assessed by Raman spectroscopy. Moreover, the effect of chronic exposure to digested nanomaterials on integrity and functionality of an in vitro model of intestinal barrier is also determined according to a second SOP. These results show a modulation of the aggregation state of FLG and GO nanoflakes after experiencing the complex environments of the different digestive compartments. In particular, chemical doping effects are observed due to FLG and GO interaction with digestive juice components. No structural changes/degradation of the nanomaterials are detected, suggesting that they are biopersistent when administered by oral route. Chronic exposure to digested graphene does not affect intestinal barrier integrity and is not associated with inflammation and cytotoxicity, though possible long-term adverse effects cannot be ruled out.

Bacteriophages targeting intestinal epithelial cells: a potential novel form of immunotherapy

In addition to their established role as a physical barrier to invading pathogens and other harmful agents, intestinal epithelial cells (IEC) are actively involved in local immune reactions. In the past years, evidence has accumulated suggesting the role of IEC in the immunopathology of intestinal inflammatory disorders (IBD). Recent advances in research on bacteriophages strongly suggest that-in addition to their established antibacterial activity-they have immunomodulating properties that are potentially useful in the clinic. We suggest that these immunomodulating phage activities targeting IEC may open novel treatment perspectives in disorders of the alimentary tract, particularly IBD.

Intestinal permeability regulation by tight junction: implication on inflammatory bowel diseases

Epithelial tight junctions (TJs) are the key structures regulating paracellular trafficking of macromolecules. The TJ is multi-protein complex that forms a selective permeable seal between adjacent epithelial cells and demarcates the boundary between apical and basolateral membrane domains. Disruption of the intestinal TJ barrier, followed by permeation of luminal noxious molecules, induces a perturbation of the mucosal immune system and inflammation, which can act as a trigger for the development of intestinal and systemic diseases. Inflammatory bowel disease (IBD) patients demonstrate increased intestinal paracellular permeability. Although it remains unclear whether barrier dysfunction precedes disease or results from active inflammation, increased intestinal TJ disruption is observed in IBD patients suggest that dysregulation of TJ barrier integrity may predispose or enhance IBD progression. Therefore, therapeutic target to restore the TJ barrier integrity may provide effective therapeutic and preventive approaches against IBD. This review discusses the molecular structure and regulation of intestinal TJs and the involvement of intestinal TJs in IBD pathogenesis.

Association of a Large Panel of Cytokine Gene Polymorphisms with Complications and Comorbidities in Type 2 Diabetes Patients

AIMS

The polymorphisms of pro- and anti-inflammatory cytokines may be involved in type 2 diabetes (T2D) pathogenesis and its complications.

METHODS

We investigated in 102 T2D patients the association of the cytokine polymorphisms in the TNF-α, IL-10, IL-6, TGF-β1, and IFN-γ genes with the T2D microvascular complications and comorbidities (hypertension, dyslipidemia, and obesity). Cytokine genotypes were determined by PCR using Cytokine Genotyping Tray kit.

RESULTS

Diabetic retinopathy was associated with GG genotype and G allele in TGF-β1 codon 25C/G polymorphism (p = 0.004 and p = 0.018) and the nephropathy was associated the lower frequency of GG genotype in IL-10 -1082G/A polymorphism (p = 0.049). Hypertension was associated with the CC genotype and C allele for IL-10 -592C/A polymorphism (p = 0.013 and p = 0.009) and higher frequencies of T (p = 0.047) and C (p = 0.033) alleles of the TGF-β1 codon 10T/C and IL-10 -819T/C polymorphisms, respectively. The TGF-β1 codon 10T/C polymorphism was associated with the BMI groups (p = 0.026): the CC genotype was more frequent in the group with BMI < 25 Kg/m(2), while the TC genotype was more frequent in the group with BMI = 30 Kg/m(2).

CONCLUSIONS

Our findings suggest that TGF-β1 and IL-10 polymorphisms are involved in complications and comorbidities in T2D patients.

The protective effect of intrasplenic transplantation of Ad-IL-18BP/IL-4 gene-modified fetal hepatocytes on ConA-induced hepatitis in mice

Background

Concanavalin A (ConA)-induced hepatitis is an experimental murine model mirroring the pathology of human autoimmune hepatitis.

Aim

To investigate the effects of intrasplenically transplanted fetal hepatocytes (BNL.CL2) transfected with recombinant adenovirus vector expressing the IL-18 binding protein (IL-18BP) and IL-4 fusion protein on ConA-induced hepatitis in mice.

Methods

Ad-IL-18BP/IL-4 was used to infect BNL.CL2 cells. IL-4 and IL-18BP fusion protein expression were detected by ELISA and Western blotting. BNL.CL2 cells infected with Ad-IL-18BP/IL-4 were intrasplenically transplanted into mice. After 10 days, mice were injected with ConA (15 mg/kg), and sacrificed 18 hours later. Liver injury was assessed by serum transaminase and liver histology. TNF-α, IL-18, IL-4, IL-10, IL-12p70 and monocyte-chemoattracting protein (MCP)-1 levels in serum and liver homogenates were detected by ELISA. Signaling molecules in liver homogenates were analyzed by Western blotting.

Results

Ad-IL-18BP/IL-4 effectively expressed the IL-18BP/IL-4 fusion protein for more than 14 days in BNL.CL12 cells. Treatment of mice with Ad-IL-18BP/IL-4-BNL.CL2 before ConA injection significantly reduced the elevated plasma levels of transaminases compared with ConA control groups. TNF-α, IL-18, IL-12p70 and MCP-1 levels in serum and liver homogenates from mice transplanted with Ad-IL-18BP/IL-4-BNL.CL2 were lower and IL-4 and IL-10 levels were higher than control groups. Phosphorylation levels of NF-κB p65, AKT, p38 and JNK1/2 in liver homogenates were markedly suppressed by Ad-IL-18BP/IL-4.

Conclusions

Ad-IL-18BP/IL-4 was effectively transfected into mouse BNL.CL2 cells. Intrasplenic transplantation of Ad-IL-18BP/IL-4-BNL.CL12 cells alleviated the severity of inflammation in ConA-induced experimental hepatitis and provides a useful basis for the targeted gene therapy of liver disease.

Regulation of intestinal epithelial permeability by tight junctions

The gastrointestinal epithelium forms the boundary between the body and external environment. It effectively provides a selective permeable barrier that limits the permeation of luminal noxious molecules, such as pathogens, toxins, and antigens, while allowing the appropriate absorption of nutrients and water. This selective permeable barrier is achieved by intercellular tight junction (TJ) structures, which regulate paracellular permeability. Disruption of the intestinal TJ barrier, followed by permeation of luminal noxious molecules, induces a perturbation of the mucosal immune system and inflammation, and can act as a trigger for the development of intestinal and systemic diseases. In this context, much effort has been taken to understand the roles of extracellular factors, including cytokines, pathogens, and food factors, for the regulation of the intestinal TJ barrier. Here, I discuss the regulation of the intestinal TJ barrier together with its implications for the pathogenesis of diseases.

Evaluation of chemical mediators and cellular response during acute and chronic gut inflammatory response induced by dextran sodium sulfate in mice

Inflammatory bowel disease (IBD) affects millions of people worldwide but its pathophysiology remains unclear. Therefore, experimental models of colitis have contributed crucially for the understanding of IBD, and also in the investigations for effective therapies. Herein we investigated the kinetics of inflammatory mediator production and cell infiltration during acute and chronic dextran sodium sulfate (DSS)-induced colitis. The induction phases with DSS were characterized by severe disease activity with massive colonic polymorphonuclear infiltration and increased levels of tumor necrosis factor-α (TNF-α), keratinocyte-derived chemokine (CXCL1/KC), interleukin (IL)-17 and vascular adhesion molecule-1 (VCAM-1). Interestingly, in the recovery periods, we found marked increase of anti-inflammatory mediators IL-10, IL-4, transforming growth factor-β (TGF-β) and cyclooxygenase 2 (COX-2) that seems be essential for the resolution of intestinal inflammation. Furthermore, nuclear factor κB (NFκB) and regulatory T cell marker forkhead box P3 (FoxP3) were increased gradually during experimental colitis, demonstrating a discrepant profile response and evident immune disbalance in the chronic phase of intestinal mucosal inflammation. Taken together, these results provide valuable information for studies on DSS-induced colitis and especially for the identification of biomarkers that predict disease course and possible therapeutic interventions.

Soluble fibers and resistant starch ameliorate disease activity in interleukin-10-deficient mice with inflammatory bowel disease

Our goal in this study was to determine the potential for dietary fibers to prevent gut inflammation in IL-10-deficient (IL-10(-/-)) mice. C57BL/6J wild-type (WT) mice (n = 90) and IL-10(-/-) mice (n = 185) were assigned to a control diet or diets supplemented with PROMITOR soluble corn fiber (SCF), STA-LITE III polydextrose (PDX), Biogum (BG), Pullulan (PI-20), PROMITOR resistant starch-75 (RS-75), SCF&BG, RS-75&BG, and inulin (4 g fiber/100 g diet). On d 47, spleen, mesenteric lymph nodes (MLN), duodenum, jejunum, ileum, and colon were macroscopically and histologically evaluated. The spleen and Peyer's patches (PP) were collected for isolating mononuclear cells and measuring the percentages of regulatory T cells (Treg) and cytokines produced by CD4(+) T cells (i.e. IFNγ and IL-10). Dietary supplementation with RS-75, SCF, RS-75&BG, and inulin ameliorated disease activity on d 47. Dietary RS-75 and inulin supplementation decreased ileal and colonic inflammatory lesions. RS-75, SCF, and inulin decreased IFNγ production by effector CD4(+) T cells from PP and RS-75 increased the IL-10-expressing cells in spleen of WT mice. Dietary SCF, PDX, BG, PI-20, and RS-75 upregulated colonic PPARγ expression in WT mice and SCF upregulated Supressor of cytokine signaling 3 in IL-10(-/-) mice. These data suggest that soluble fibers and resistant starch influence Treg cells, IFNγ, and colonic PPARγ expression to suppress gut inflammation.

Endogenous expression of interleukin-4 regulates macrophage activation and confines cavity formation after traumatic spinal cord injury

Traumatic spinal cord injury (SCI) triggers inflammatory reactions in which various types of cells and cytokines are involved. Several proinflammatory cytokines are up-regulated after SCI and play crucial roles in determining the extent of secondary tissue damage. However, relatively little is known about antiinflammatory cytokines and their roles in spinal cord trauma. Recent studies have shown that an antiinflammatory cytokine, interleukin-4 (IL-4), is expressed and exerts various modulatory effects in CNS inflammation. We found in the present study that IL-4 was highly expressed at 24 hr after contusive SCI in rats and declined thereafter, with concurrent up-regulation of IL-4 receptor subunit IL-4alpha. The majority of IL-4-producing cells were myeloperoxidase-positive neutrophils. Injection of neutralizing antibody against IL-4 into the contused spinal cord did not significantly affect the expression levels of proinflammatory cytokines such as IL-1beta, IL-6, and tumor necrosis factor-alpha or other antiinflammatory cytokines such as IL-10 and transforming growth factor-beta. Instead, attenuation of IL-4 activity led to a marked increase in the extent of ED1-positive macrophage activation along the rostrocaudal extent at 7 days after injury. The enhanced macrophage activation was preceded by an increase in the level of monocyte chemoattractant protein-1 (MCP-1/CCL2). Finally, IL-4 neutralization resulted in more extensive cavitation at 4 weeks after injury. These results suggest that endogenous expression of antiinflammatory cytokine IL-4 regulates the extent of acute macrophage activation and confines the ensuing secondary cavity formation after spinal cord trauma.

Association of interleukin-10 polymorphisms with cytokines in type 2 diabetic nephropathy

OBJECTIVE

Interleukin-10 (IL-10) polymorphic variants are linked with cytokine production and are involved in many chronic inflammatory diseases, including type 2 diabetes mellitus (T2DM). We investigated the hypothesis that IL-10 promoter polymorphisms may be associated with cytokine expressions involved in the progression of diabetic nephropathy (DN).

STUDY DESIGN

A total of 72 Taiwanese subjects were included in this study; along with a control group, patients had a diagnosis of DN lasting ≥2 years, and patients had a diagnosis of T2DM with normal renal functions lasting ≥5 years. Their IL-10 and tumor necrosis factor-α (TNF-α) genotyping and association of blood chemistry, plasma IL-10, TNF-α, and monocyte chemoattract protein-1 (MCP-1), and urinary MCP-1 were investigated.

RESULTS

The IL-10-(-592) genotype exhibited significant association with cytokine expressions in DN: significantly higher TNF-α and lower plasma IL-10 levels were observed in IL-10-(-592)AA, whereas a higher urine MCP-1 level was found in Taiwanese patients with the IL-10-(-592)CC genotype.

CONCLUSIONS

IL-10-(-592) promoter polymorphisms may influence IL-10 and MCP-1 production, which may be an indicator of nephropathy risk in Taiwanese T2DM patients.

Interleukin (IL)-4 induces leukocyte infiltration in vivo by an indirect mechanism

Interleukin (IL)-4 is a cytokine known mainly for its anti-inflammatory activity. Using the in vivo murine air pouch model, we found that IL-4 significantly increased the number of leukocytes after 9 hours of treatment, consisting mainly of neutrophil (60%) and monocytic (40%) cell populations. Using an antibody array, we found that the expression of several analytes (predominantly CCL2) was increased by IL-4 before the arrival of leukocytes. The IL-4-induced expression of CCL-2 was confirmed by ELISA. Air pouch resident lining cells were harvested and were found to express IL-4Rα. CCL2 mRNA expression was monitored in lining cells, cells isolated from the air pouch skin, in RAW264.7 macrophage and in epithelial Mode-K cells and its expression was increased in response to IL-4 in all conditions. We conclude that IL-4 can attract leukocytes in vivo by an indirect mechanism involving the production of several analytes by, at least, resident cells.

Regulatory effect of heat shock protein 70 in stress-induced rat intestinal epithelial barrier dysfunction

BACKGROUND

Psychological stress is one of the factors associated with many human diseases; the mechanisms need to be further understood.

METHODS

Rats were subjected to chronic water avoid stress. Intestinal epithelial heat shock protein (HSP) 70 was evaluated. The intestinal epithelial permeability was examined with Ussing chamber technique.

RESULTS

HSP70 was detected in normal intestinal epithelial cells. Psychological stress decreased HSP70 in the intestinal epithelial cells that correlated with the stress-induced intestinal epithelial hyperpermeability. Pretreatment with HSP70 abrogated stress-induced intestinal barrier dysfunction.

CONCLUSIONS

Chronic stress inhibits HSP70 activity in rat intestinal epithelial layer that is associated with intestinal epithelial barrier dysfunction, which can be prevented by pretreatment with HSP70 protein. (Yang PC, Tu YH, Perdue MH, Oluwole C, Struiksma S. Regulatory effect of heat shock protein 70 in stress-induced rat intestinal epithelial barrier dysfunction.

Different effect of glutamine on macrophage tumor necrosis factor-alpha release and heat shock protein 72 expression in vitro and in vivo

Macrophage plays a vital role in sepsis. However, the modulatory effect of glutamine (Gln) on macrophage/ monocyte-mediate cytokines release is still controversial. Thus, we investigated the effect of Gln on macrophage tumor necrosis factor (TNF)-alpha release and heat shock protein (HSP) 72 expression in vivo and in vitro. Data from our study indicated that the increase of HSP72 expression was significant at 8 mM of Gln 4 h after lipopolysaccharide (LPS) stimulation and became independent of Gln concentrations at 24 h, whereas TNF-alpha release was dose- and time-dependent on Gln. Heat stress (HS) induced more HSP72 and less TNF-alpha production compared with the non-HS group. However, the production of TNF-alpha in cells pretreated with HS was increased with increasing concentrations of Gln. Treatment with various concentrations of Gln for 1 h and then 0.5 mM Gln for 4 h led to an increase in HSP72 expression, but not in TNF-alpha production. In sepsis model mice, Gln treatment led to a significantly lower intracellular TNF-alphalevel and an increase in HSP72 expression in mouse peritoneal macrophages. Our results demonstrate that Gln directly increases TNF-alpha release of LPS-stimulated RAW264.7 macrophages in a dose-dependent manner, and also decreases mouse peritoneal macrophages TNF-a release in the sepsis model. Taken together, our data suggest that there may be more additional pathways by which Gln modulates cytokine production besides HSP72 expression in macrophage during sepsis.

IL-10 deficiency augments acute lung but not liver injury in hemorrhagic shock

In hemorrhagic shock and trauma, patients are prone to develop systemic inflammation with remote organ dysfunction, which is thought to be caused by pro-inflammatory mediators. This study investigates the role of the immuno-modulatory cytokine IL-10 in the development of organ dysfunction following hemorrhagic shock. Male C57/BL6 and IL-10 KO mice were subjected to volume controlled hemorrhagic shock for 3h followed by resuscitation. Animals were either sacrificed 3 or 24h after resuscitation. To assess systemic inflammation, serum IL-6, IL-10, KC, and MCP-1 concentrations were measured with the Luminex multiplexing platform; acute lung injury (ALI) was assessed by pulmonary myeloperoxidase (MPO) activity and lung histology and acute liver injury was assessed by hepatic MPO activity, hepatic IL-6 levels, and serum ALT levels. There was a trend towards increased IL-6 and KC serum levels 3h after resuscitation in IL-10 KO as compared to C57/BL6 mice; however this did not reach statistical significance. Serum MCP-1 levels were significantly increased in IL-10 KO mice 3 and 24 h following resuscitation as compared to C57/BL6 mice. In IL-10 KO mice, pulmonary MPO activity was significantly increased 3 h following resuscitation and after 24 h histological signs of acute lung injury were more apparent than in C57/BL6 mice. In contrast, no significant differences in any liver parameters were detected between IL-10 KO and C57/BL6 mice. Our data indicate that an endogenous IL-10 deficiency augments acute lung but not liver injury following hemorrhagic shock.

Hydrodynamic-based delivery of an interleukin-22-Ig fusion gene ameliorates experimental autoimmune myocarditis in rats

IL-22 is one of several cytokines with limited homology to IL-10. However, the biological activities of IL-22 are mostly unknown. The purpose of this study was to evaluate the effect of IL-22 on rat experimental autoimmune myocarditis (EAM) and elucidate an aspect of the biological activities of IL-22. Rats were immunized on day 0; IL-22-Ig-treated rats were injected with pCAGGS-IL-22-Ig and control rats with pCAGGS-Ig using hydrodynamics-based gene delivery on day 1 or day 6. IL-22-Ig gene therapy administered on day 1 or day 6 after immunization was effective in controlling EAM as monitored by the heart weight to body weight ratio, and the myocarditis area in rats was sacrificed on day 17. Examination of the expression of IL-22-related genes in purified cells from EAM hearts suggested that IL-22-Ig acting target cells were noncardiomyocytic (NC) noninflammatory cells such as fibroblasts, smooth muscle cells, and endothelial cells. Therefore, we examined the effect of rIL-22 or serum containing IL-22-Ig on the expression of immune-relevant genes in IL-1-stimulated NC cells cultured from EAM hearts. Results showed that the expression of immunologic molecules (PGE synthase, cyclooxygenase-2, MIP-2, MCP-1, IL-6, and cytokine-induced neutrophil chemoattractant-2) in IL-1-stimulated NC cells was significantly decreased by rIL-22 or serum containing IL-22-Ig. EAM was suppressed by hydrodynamics-based delivery of plasmid DNA encoding IL-22-Ig, and the reason for this effectiveness may be that IL-22 suppressed gene expression of PG synthases, IL-6, and chemokines in activated NC noninflammatory cells.

Role of interleukin (IL-10) in probiotic-mediated immune modulation: an assessment in wild-type and IL-10 knock-out mice

While the impact of Bifidobacterium infantis 35624 and other probiotics on cytokines has been shown in established colitis, the effects of B. infantis consumption in pre-inflammation of interleukin (IL)-10 knock-out (KO) mice and on the wild-type (WT) C57Bl/6 mice have not been well demonstrated. The objective of this study was to examine cytokine responses in mucosal and systemic lymphoid compartments of IL-10 KO mice early in disease and to compare with control WT mice. Mice were fed B. infantis or placebo for 5 weeks and culled prior to the onset of chronic intestinal inflammation (12-14 weeks). The spleen, Peyer's patches and intestinal mucosa were removed and stimulated with various bacterial stimuli. Cytokine levels were measured by enzyme-linked immunosorbent assay. While basal intestinal and systemic cytokine profiles of WT and IL-10 KO mice were similar, transforming growth factor (TGF)-beta was reduced in the spleen of IL-10 KO mice. Following probiotic consumption, interferon (IFN)-gamma was reduced in the Peyer's patch of both WT and IL-10 KO mice. Alterations in IFN-gamma in the Peyer's patches of WT mice (enhancement) versus IL-10 KO (reduction) were observed following in vitro stimulation with salmonella. Differential IL-12p40, CCL2 and CCL5 responses were also observed in IL-10 KO mice and WT mice. The cytokine profile of IL-10 KO mice in early disease was similar to that of WT mice. The most pronounced changes occurred in the Peyer's patch of IL-10 KO mice, suggesting a probiotic mechanism of action independent of IL-10. This study provides a rationale for the use of B. infantis 35624 for the treatment of gastrointestinal inflammation.

IL-1beta and TNF-alpha induce increased expression of CCL28 by airway epithelial cells via an NFkappaB-dependent pathway

CCL28 is a mucosal chemokine that attracts eosinophils and T cells via the receptors CCR3 and CCR10. Consequently, it is a candidate mediator of the pathology associated with asthma. This study examined constitutive and induced expression of CCL28 by A549 human airway epithelial-like cells. Real-time RT-PCR and ELISA of cultured cells and supernatants revealed constitutive levels of CCL28 expression to be low, whereas IL-1beta and TNF-alpha, induced significantly increased expression. Observations from induced sputum and human airway biopsies supported this. Signal transduction studies revealed that IL-1beta and TNF-alpha stimulation induced NFkappaB phosphorylation in A549 cells, but antagonist inhibition of NFkappaB p50-p65 phosphorylation correlated with marked reduction of IL-1beta or TNF-alpha induced CCL28 expression. Together these studies imply a role for CCL28 in the orchestration of airway inflammation, and suggest that CCL28 is one link between microbial insult and the exacerbation of pathologies such as asthma, through an NFkappaB-dependent mechanism.

Chemokines in host-parasite interactions in leishmaniasis

Crucial to the defense against leishmaniasis is the ability of the host to mount a cell-mediated immune response capable of controlling and/or eliminating the parasite. Cell recruitment to the site of infection is essential to the development of the host cellular immune response. The process is controlled by chemokines, which are chemotactic cytokines produced by leukocytes and tissue cells.

Interleukin-4 and 13 concentrations in infants at risk to develop Bronchopulmonary Dysplasia

BACKGROUND

An exaggerated inflammatory response occurs in the first few days of life in infants who subsequently develop bronchopulmonary dysplasia (BPD). The increase of inflammatory cytokines in many disease processes is generally balanced by a rise in anti-inflammatory cytokines. Interleukin-4 (IL-4) and interleukin-13 (IL-13) have been shown to inhibit production of several inflammatory cytokines important in the development of BPD.

METHODS

We sought to determine if a correlation exists between the presence or absence of IL-4 and IL-13 in tracheal aspirates (TA) during the first 3 weeks of life and the development of BPD in premature infants. Serial TAs were prospectively obtained from 36 very low birth weight infants and IL-4 and IL-13 concentrations were determined by ELISA.

RESULTS

Infants who developed BPD (n = 19) were less mature (25.3 +/- 0.02 wks vs. 27.8 +/- 0.05 wks; p < 0.001), and had lower birth weights (739 +/- 27 g vs.1052 +/- 41 g; p < 0.001). IL-4 and IL-13 were detectable in only 27 of 132 and 9 of 132 samples assayed respectively. Furthermore, the levels detected for IL-4 and IL-13 were very low and did not correlate with the development of BPD.

CONCLUSIONS

TA concentrations of IL-4 and IL-13 do not increase significantly during acute lung injury in premature infants.

Intestinal epithelial CD23 mediates enhanced antigen transport in allergy: evidence for novel splice forms

We previously demonstrated enhanced transepithelial antigen transport in the intestine of allergic rodents associated with elevated expression of the low-affinity IgE receptor CD23 on enterocytes. Here, we examined the role of CD23 in the transport phenomenon using CD23-/- mice and characterized the isoform of intestinal epithelial CD23. Jejunal segments of sensitized mice were challenged with antigen. Enhanced transepithelial antigen transport and transmucosal antigen flux were found in the intestine of sensitized CD23+/+ but not CD23-/- mice. RT-PCR showed that enterocytes expressed only the isoform b of CD23. Sequencing revealed classic and alternative CD23b transcripts lacking exon 5 (bDelta5) or 6, all of which were translated into functional IgE receptors. The protein encoded by bDelta5 but not the classic b transcript was able to mediate the uptake of anti-CD23 or IgE, whereas both CD23 proteins were internalized after binding to IgE/antigen complexes. Our results suggest that the classic and alternative forms of CD23b display distinct endocytic properties, suggesting that they are likely to play different roles in transepithelial transport of IgE and allergens.

Interleukin-13 and tumor necrosis factor-beta differentially regulate the production of cytokines by cultured human endometrial stromal cells

OBJECTIVE

To evaluate the effects of interleukin (IL)-13, a T-helper (Th)2 cytokine, and tumor necrosis factor (TNF)-beta, a Th1 cytokine, on the production of IL-6 family cytokines and chemokines by endometrial stromal cells (ESC).

DESIGN

The effects of IL-13 and TNF-beta, on the production of IL-6, IL-11, leukemia inhibitory factor (LIF), IL-8, growth-regulated oncogene alpha (GROalpha), monocyte chemoattractant protein-1 (MCP-1), regulated on activation, T-cell expressed and secreted (RANTES), and eotaxin were investigated.

SETTING

Research laboratory at a medical university.

PATIENT(S)

Thirteen endometrial specimens in the late proliferative phase were used.

INTERVENTION(S)

The ESC were incubated for 24 hours with recombinant human IL-13 and recombinant human TNF-beta.

MAIN OUTCOME MEASURE(S)

The concentration of IL-6, IL-11, LIF, IL-8, GROalpha, MCP-1, RANTES, and eotaxin in the culture media was measured using ELISA.

RESULT(S)

The increase in levels of IL-6, IL-8, MCP-1, and eotaxin in the culture media of ESC paralleled the addition of increasing amounts of IL-13 and TNF-beta, whereas the levels of IL-11 and LIF were decreased with increasing amounts of IL-13, but were increased with increasing amounts of TNF-beta. Tumor necrosis factor-beta enhanced the production of GROalpha and RANTES in dose-dependent manner; however, IL-13 did not affect the expression of GROalpha or RANTES.

CONCLUSION(S)

These results suggest that IL-13 and TNF-beta secreted in the cyclic endometrial tissue and in the decidua may differentially regulate the production of IL-6 family cytokines and chemokines by ESC. The controlled expression of these cytokines in the endometrium may contribute to the modulation of the immune reaction during the menstrual cycle and in early pregnancy by the regulation of leukocyte trafficking and functions.

Ileal cytokine dysregulation in experimental necrotizing enterocolitis is reduced by epidermal growth factor

BACKGROUND

Necrotizing enterocolitis (NEC) is the most common gastrointestinal disease of premature infants. We have shown in previous studies that proinflammatory interleukin-18 and interleukin-12 are up-regulated in the ileum of rats with experimental NEC and that epidermal growth factor (EGF) reduces the development of disease. Here we investigated whether the protective effects of EGF are a result of changes in ileal interleukin-18, interleukin-12 and/or antiinflammatory interleukin-10.

METHODS

Newborn rats were artificially fed with either growth-factor-free rat milk substitute (RMS) or RMS supplemented with 500 ng/mL EGF (RMS + EGF) and NEC was induced via exposure to asphyxia and cold stress. Cytokine expression and localization were assessed using reverse-transcription real-time polymerase chain reaction and immunohistology/confocal microscopy.

RESULTS

Enteral administration of EGF (RMS + EGF) decreased overproduction of interleukin-18 and increased interleukin-10 production in the ileum. Furthermore, increased interleukin-10 production was associated with up-regulation of the transcription factor Sp1 in RMS + EGF rats.

CONCLUSIONS

These data suggest that EGF may reduce NEC via increased interleukin-10 and decreased interleukin-18 and that EGF-mediated up-regulation of Sp1 may account for the increased interleukin-10.

IL-10 receptor and coreceptor expression in quiescent and activated hepatic stellate cells

Interleukin (IL)-10 expression is induced in activated hepatic stellate cells (HSC) in vitro and in vivo. We analyzed expression of IL-10 receptor (IL-10R) and coreceptor cytokine receptor family (CRF2-4) in HSC. We aimed to clone and sequence partial cDNA for rat IL-10R and CRF2-4, determine their expression in activated rat HSC in vivo and in vitro, and examine the biological responsiveness of HSC to exogenous IL-10. PCR cloning and sequencing of partial rat IL-10R and CRF2-4 cDNAs revealed 86% homology with corresponding mouse sequences. In hepatic macrophages, Northern blot with cloned IL-10R cDNA detected an expected 3.5-kb transcript, and IL-10R and CRF2-4 mRNAs showed steady constitutive expression after in vitro lipopolysaccharide treatment or cholestatic liver injury. IL-10R mRNA expression, as confirmed by immunohistochemistry, was induced 20.1- and 8.6-fold in HSC from cholestatic livers and 7-day culture-activated HSC, respectively but CRF2-4 mRNA levels were unchanged. Under serum-free conditions, IL-10 had minimal effects on collagen production but reduced DNA synthesis, matrix metalloprotease-2 mRNA levels, and activity in HSC. With serum, IL-10 inhibited both collagen production and DNA synthesis but had no effect on procollagen-alpha(1)(I) mRNA levels. This shows concomitant induction of IL-10R but not CRF2-4 to that of IL-10 by activated HSC in vitro and in vivo and associated acquisition of the responsiveness to IL-10, entailing complex effects on HSC.

Molecular machinations: chemokine signals in host-pathogen interactions

Chemokines and their G-protein-coupled receptors represent an ancient and complex system of cellular communication participating in growth, development, homeostasis and immunity. Chemokine production has been detected in virtually every microbial infection examined; however, the precise role of chemokines is still far from clear. In most cases they appear to promote host resistance by mobilizing leukocytes and activating immune functions that kill, expel, or sequester pathogens. In other cases, the chemokine system has been pirated by pathogens, especially protozoa and viruses, which have exploited host chemokine receptors as modes of cellular invasion or developed chemokine mimics and binding proteins that act as antagonists or inappropriate agonists. Understanding microbial mechanisms of chemokine evasion will potentially lead to novel antimicrobial and anti-inflammatory therapeutic agents.

Characterization of conditions for the primary culture of human small intestinal epithelial cells

Intestinal epithelial cells (IECs) are important for many aspects of gut physiology and pathology. Different approaches have been tried for the primary culture of human IECs, with varying degrees of success, as apoptosis easily occurs. Our aim was to develop a method for primary culture of human IECs from biopsy material. IECs and Lamina propria (LP) cells were liberated from duodenal biopsies obtained from subjects undergoing routine endoscopy for clinical investigations, whose small bowel was macroscopically normal. IECs were cultured on collagen membranes in a 12-well tissue culture cluster, with LP cells and allogeneic Epstein-Barr Virus (EBV)-transformed B lymphocytes (allo-B cells) underneath, in the well. Cultured IECs were characterized by light and confocal microscopy. Cytokine levels in culture supernatants were measured by ELISA. Cells showed the columnar morphology of IECs, even after several days in culture. Best results were obtained from IECs cultured above both LP and allo-B cells. IECs did not form monolayers as do transformed epithelial cell lines, but they did preserve their original cell-cell contacts. Analysis of culture supernatants showed that IL-10 was produced by IECs initially, but IL-1ra was produced by LP cells in the underlying wells with increasing time in culture. Very little IL-1 beta was produced from any cultures. These results show that IECs can be isolated and maintained in primary culture for a short while, which could open new possibilities for research using patient material instead of cell lines.

Colonic epithelial cells induce endothelial cell expression of ICAM-1 and VCAM-1 by a NF-kappaB-dependent mechanism

Epithelial cells are positioned in close proximity to endothelial cells. A non-contact coculture system was used to investigate whether colonic epithelial cells activated with various cytokines are able to provide signals that can modulate ICAM-1 and VCAM-1 expression on endothelial cells. Coculture of human umbilical vein endothelial cells (HUVEC) and human microvascular endothelial cells (HMEC-1) with TNF-alpha/IFN-gamma-stimulated human colon epithelial cell lines led to a significant up-regulation of endothelial ICAM-1 and VCAM-1 expression. Increased ICAM-1 and VCAM-1 expression by endothelial cells was accompanied by an increase in endothelial cell NF-kappaB p65 and NF-kappaB-DNA-binding activity. Inhibition of endothelial NF-kappaB activation using the proteosome inhibitors MG-132 and BAY 11-7082 resulted in a significant decrease of ICAM-1 expression, indicating an important role for NF-kappaB in this response. This cross-talk may represent a biological mechanism for the gut epithelium to control the colonic inflammatory response and the subsequent immune cell recruitment during inflammation.

Control of chemokine production at the blood-retina barrier

Chemokine production at the blood-retina barrier probably plays a critical role in determining the influx of tissue-damaging cells from the circulation into the retina during inflammation. The blood-retina barrier comprises the retinal microvascular endothelium and the retinal pigment epithelium. Chemokine expression and production by human retinal microvascular endothelial cells (REC) have never been reported previously, so we examined the in vitro expression and production of monocyte chemoattractant protein-1 (MCP-1), regulated on activation of normal T-cell expressed and secreted (RANTES), macrophage inflammatory protein (MIP)-1alpha, MIP-1beta, interleukin (IL)-8, epithelial cell-derived neutrophil activating protein-78 (ENA-78) and growth related oncogene alpha (GROalpha) in these cells, both unstimulated and stimulated by cytokines likely to be present during the evolution of an inflammatory response. We compared this to expression and production of these chemokines in vitro in human retinal pigment epithelial cells (RPE). MCP-1 was expressed and produced constitutively by REC but all the chemokines were produced in greater amounts upon stimulation with the proinflammatory cytokines IL-1beta and tumour necrosis factor-alpha (TNF-alpha). MCP-1 and IL-8 were produced at much higher levels than the other chemokines tested. MIP-1alpha and MIP-1beta were present only at low levels, even after stimulation with IL-1beta and TNF-alpha. Cytokines with greater anti-inflammatory activity, such as IL-4, IL-10, IL-13, transforming growth factor-beta (TGF-beta) and IL-6, had little effect on chemokine production either by REC alone or after stimulation with IL-1beta and TNF-alpha. RPE, although a very different cell type, showed a similar pattern of expression and production of chemokines, indicating the site-specific nature of chemokine production. Chemokine production by REC and RPE is probably significant in selective leucocyte recruitment during the development of inflammation in the retina.

Control of chemokine production at the blood-retina barrier

Chemokine production at the blood-retina barrier probably plays a critical role in determining the influx of tissue-damaging cells from the circulation into the retina during inflammation. The blood-retina barrier comprises the retinal microvascular endothelium and the retinal pigment epithelium. Chemokine expression and production by human retinal microvascular endothelial cells (REC) have never been reported previously, so we examined the in vitro expression and production of monocyte chemoattractant protein-1 (MCP-1), regulated on activation of normal T-cell expressed and secreted (RANTES), macrophage inflammatory protein (MIP)-1alpha, MIP-1beta, interleukin (IL)-8, epithelial cell-derived neutrophil activating protein-78 (ENA-78) and growth related oncogene alpha (GROalpha) in these cells, both unstimulated and stimulated by cytokines likely to be present during the evolution of an inflammatory response. We compared this to expression and production of these chemokines in vitro in human retinal pigment epithelial cells (RPE). MCP-1 was expressed and produced constitutively by REC but all the chemokines were produced in greater amounts upon stimulation with the proinflammatory cytokines IL-1beta and tumour necrosis factor-alpha (TNF-alpha). MCP-1 and IL-8 were produced at much higher levels than the other chemokines tested. MIP-1alpha and MIP-1beta were present only at low levels, even after stimulation with IL-1beta and TNF-alpha. Cytokines with greater anti-inflammatory activity, such as IL-4, IL-10, IL-13, transforming growth factor-beta (TGF-beta) and IL-6, had little effect on chemokine production either by REC alone or after stimulation with IL-1beta and TNF-alpha. RPE, although a very different cell type, showed a similar pattern of expression and production of chemokines, indicating the site-specific nature of chemokine production. Chemokine production by REC and RPE is probably significant in selective leucocyte recruitment during the development of inflammation in the retina.

Non-pathogenic bacteria elicit a differential cytokine response by intestinal epithelial cell/leucocyte co-cultures

BACKGROUND AND AIM

Intestinal epithelial cells (IEC) are thought to participate in the mucosal defence against bacteria and in the regulation of mucosal tissue homeostasis. Reactivity of IEC to bacterial signals may depend on interactions with immunocompetent cells. To address the question of whether non-pathogenic bacteria modify the immune response of the intestinal epithelium, we co-cultivated enterocyte-like CaCO-2 cells with human blood leucocytes in separate compartments of transwell cultures.

METHODS

CaCO-2/PBMC co-cultures were stimulated with non-pathogenic bacteria and enteropathogenic Escherichia coli. Expression of tumour necrosis factor alpha (TNF-alpha), interleukin (IL)-1beta, IL-8, monocyte chemoattracting protein 1 (MCP-1), and IL-10 was studied by enzyme linked immunosorbent assays (cytokine secretion) and by semiquantitative reverse transcription-polymerase chain reaction.

RESULTS

Challenge of CaCO-2 cells with non-pathogenic E coli and Lactobacillus sakei induced expression of IL-8, MCP-1, IL-1beta, and TNF-alpha mRNA in the presence of underlying leucocytes. Leucocyte sensitised CaCO-2 cells produced TNF-alpha and IL-1beta whereas IL-10 was exclusively secreted by human peripheral blood mononuclear cells. CaCO-2 cells alone remained hyporesponsive to the bacterial challenge. Lactobacillus johnsonii, an intestinal isolate, showed reduced potential to induce proinflammatory cytokines but increased transforming growth factor beta mRNA in leucocyte sensitised CaCO-2 cells. TNF-alpha was identified as one of the early mediators involved in cellular cross talk. In the presence of leucocytes, discriminative activation of CaCO-2 cells was observed between enteropathogenic E coli and non-pathogenic bacteria.

CONCLUSION

The differential recognition of non-pathogenic bacteria by CaCO-2 cells required the presence of underlying leucocytes. These results strengthen the hypothesis that bacterial signalling at the mucosal surface is dependent on a network of cellular interactions.

Interleukin-4 and IFN-gamma differentially stimulate macrophage chemoattractant protein-1 (MCP-1) and eotaxin production by intestinal epithelial cells

When the intestine becomes infected by pathogenic organisms, intestinal epithelial cells (IEC) respond with the production of chemokines, which then attract and activate specific subsets of leukocytes. During chronic inflammation, the panel of IEC chemokines produced likely represents the net effect of a plethora of mediators present in the milieu, including cytokines from activated T lymphocytes. To explore the influence of T lymphocyte cytokines, we treated IEC-18 cells with interferon-y (IFN-gamma) and interleukin-4 (IL-4) and measured the effect on production of the CC chemokines, monocyte chemoattractant protein-1 (MCP-1) and eotaxin, and the CXC chemokine, macrophage inflammatory protein-2 (MIP-2). Both IFN-gamma and IL-4 enhanced MCP-1 mRNA levels but with different kinetics. IFN-gamma stimulated a transient increase in MCP-1 mRNA levels, which peaked at 2 h, whereas IL-4-stimulated MCP-1 mRNA levels were markedly increased at 1 h and remained elevated at all time points studied. With each stimulus, the increase in MCP-1 mRNA levels was accompanied by a steady time-dependent increase in MCP-1 secretion. In addition, treatment with IFN-gamma or IL-4 enhanced IL-1beta-stimulated MCP-1 mRNA production and protein secretion. Eotaxin mRNA was detectable in unstimulated IEC-18 cells, and IL-4 but not IFN-gamma caused a rapid enhancement in levels, which remained elevated for 24 h after treatment. Finally, IL-1beta but not IFN-gamma or IL-4 enhanced MIP-2 mRNA levels. Knowledge gained from studying the outcome of T lymphocyte-derived stimuli will help understand the complex sequence of events during chronic intestinal inflammation.

Characterization of M cell development during indomethacin-induced ileitis in rats

BACKGROUND

M cells play an important role in the intestinal immune system as they have a high capacity for transcytosis of a wide range of microorganisms and macromolecules. However, little is known about the role of M cells during intestinal inflammation.

AIM

We studied M cell development during indomethacin-induced intestinal inflammation in rats.

METHODS

Ileitis in rats was induced by two subcutaneous injections with indomethacin (7.5 mg/kg) given 24 h apart. Rats were sacrificed after 14 days and tissue was analysed by fluorescence microscopy and electron microscopy. M cells could be visualized by using the FITC-labelled mAb anti-cytokeratin (CK)-8 (clone 4.1.18), which was recently identified as specific M cell marker in rats. The number of cytokeratin-8 positive M cells was related to the surface of the follicle associated epithelium. For morphological studies, we used both transmission electron microscopy (T.E.M.) and scanning electron microscopy (S.E.M.).

RESULTS

In non-inflamed ileum M cells were scarce. Only 4% of the follicle associated epithelium were M cells, whereas an increase of M cells up to 11% was found in inflamed follicle associated epithelium (P < 0.001). The rate of M cell induction depended on the macroscopic degree of inflammation. T.E.M./S.E.M. studies showed that in inflamed tissue most M cells underwent apoptosis with typical morphological signs. In contrast to apoptotic M cells, the neighbouring enterocytes usually appeared intact. The number of mononuclear cells below the follicle associated epithelium was significantly increased. S.E.M. studies revealed that during induced ileitis mononuclear cells migrated from the lamina propria into the gut lumen by passing through apoptotic M cells.

CONCLUSIONS

During indomethacin-induced ileitis in rats the increase in M cell number in association with apoptosis of M cells may alter the intestinal barrier function. These observations may play a pivotal role in the pathogenesis of chronic intestinal inflammation, e.g. in inflammatory bowel disease.