Correlations between interleukin-8, and myeloperoxidase or luminol-dependent chemiluminescence in inflamed mucosa of ulcerative colitis

Peripheral blood neutrophil-to-lymphocyte ratio in inflammatory bowel disease and disease activity: A meta-analysis

OBJECTIVE

The peripheral blood neutrophil-to-lymphocyte ratio (NLR) is a valuable predictor of clinical disease activity in inflammatory bowel disease (IBD). Therefore, we conducted a meta-analysis to evaluate the clinical significance of peripheral blood NLR in IBD patients.

METHODS

A comprehensive literature search was conducted by searching PubMed, Embase, Web of Science, Cochrane Library, and Chinese databases from inception to May 10, 2021. We used the standard mean difference (SMD) with a 95% confidence interval (CI) to estimate the pooled effect and subgroup analysis to investigate heterogeneity.

RESULTS

Sixteen studies including 2185 IBD patients and 993 healthy controls (HCs) were enrolled in this study. The peripheral blood NLR values were significantly higher in 1,092 IBD patients than in 933 HCs (SMD = 1.54, 95% CI = 1.05-2.02, P < 0.001) and in 1,269 patients with active IBD than in 1,056 patients with remissive IBD (SMD = 1.55, 95% CI = 1.06-2.05, P < 0.001). Subgroup analysis of the major subtypes of IBD revealed significantly elevated peripheral blood NLR values in patients with active ulcerative colitis (UC) compared to HCs (SMD = 2.04), remissive UC than HCs (SMD = 0.63), and active UC than in those with remissive UC (SMD = 1.32) (P < 0.05). Both Crohn's disease (CD) patients and active CD patients had significantly elevated peripheral blood NLR values than HCs with the SMD of 0.52 and 3.53 (P < 0.001).

CONCLUSIONS

Peripheral blood NLR could serve as a valuable biomarker for predicting disease severity in IBD patients.

The role of sodium thiocyanate supplementation during dextran sodium sulphate-stimulated experimental colitis

Ulcerative colitis is a condition characterised by the infiltration of leukocytes into the gastrointestinal wall. Leukocyte-MPO catalyses hypochlorous acid (HOCl) and hypothiocyanous acid (HOSCN) formation from chloride (Cl^-) and thiocyanous (SCN^-) anions, respectively. While HOCl indiscriminately oxidises biomolecules, HOSCN primarily targets low-molecular weight protein thiols. Oxidative damage mediated by HOSCN may be reversible, potentially decreasing MPO-associated host tissue destruction. This study investigated the effect of SCN^- supplementation in a model of acute colitis. Female mice were supplemented dextran sodium sulphate (DSS, 3% w/v) in the presence of 10 mM Cl^- or SCN^- in drinking water ad libitum, or with salts (NaCl and NaSCN only) or water only (controls). Behavioural studies showed mice tolerated NaSCN and NaCl-treated water with water-seeking frequency. Ion-exchange chromatography showed increased fecal and plasma SCN^- levels in thiocyanate supplemented mice; plasma SCN^- reached similar fold-increase for smokers. Overall there was no difference in weight loss and clinical score, mucin levels, crypt integrity and extent of cellular infiltration between DSS/SCN^- and DSS/Cl^- groups. Neutrophil recruitment remained unchanged in DSS-treated mice, as assessed by fecal calprotectin levels. Total thiol and tyrosine phosphatase activity remained unchanged between DSS/Cl^- and DSS/SCN^- groups, however, colonic tissue showed a trend in decreased 3-chlorotyrosine (1.5-fold reduction, p < 0.051) and marked increase in colonic GCLC, the rate-limiting enzyme in glutathione synthesis. These data suggest that SCN^- administration can modulate MPO activity towards a HOSCN-specific pathway, however, this does not alter the development of colitis within a DSS murine model.

The nitroxide 4-methoxy-tempo inhibits the pathogenesis of dextran sodium sulfate-stimulated experimental colitis

Inflammatory bowel disease (IBD) is a chronic condition characterised by leukocyte recruitment to the gut mucosa. Leukocyte myeloperoxidase (MPO) produces the two-electron oxidant hypochlorous acid (HOCl), damaging tissue and playing a role in cellular recruitment, thereby exacerbating gut injury. We tested whether the MPO-inhibitor, 4-Methoxy-TEMPO (MetT), ameliorates experimental IBD. Colitis was induced in C57BL/6 mice by 3% w/v dextran-sodium-sulfate (DSS) in drinking water ad libitum over 9-days with MetT (15 mg/kg; via i. p. injection) or vehicle control (10% v/v DMSO+90% v/v phosphate buffered saline) administered twice daily during DSS challenge. MetT attenuated body-weight loss (50%, p < 0.05, n = 6), improved clinical score (53%, p < 0.05, n = 6) and inhibited serum lipid peroxidation. Histopathological damage decreased markedly in MetT-treated mice, as judged by maintenance of crypt integrity, goblet cell density and decreased cellular infiltrate. Colonic Ly6C⁺, MPO-labelled cells and 3-chlorotyrosine (3-Cl-Tyr) decreased in MetT-treated mice, although biomarkers for nitrosative stress (3-nitro-tyrosine-tyrosine; 3-NO₂-Tyr) and low-molecular weight thiol damage (assessed as glutathione sulfonamide; GSA) were unchanged. Interestingly, MetT did not significantly impact colonic IL-10 and IL-6 levels, suggesting a non-immunomodulatory pathway. Overall, MetT ameliorated the severity of experimental IBD, likely via a mechanism involving the modulation of MPO-mediated damage.

Bifidobacterium longum subsp. infantis BB-02 attenuates acute murine experimental model of inflammatory bowel disease

Inflammatory bowel diseases (IBD) are chronic inflammatory conditions, characterised by remissions and relapses episodes, whose main manifestations are ulcerative colitis and Crohn's disease. Ulcerative colitis (UC), one of the main forms of IBD, has as standard treatment the use of corticosteroids and anti-inflammatory drugs. The use of antibiotics has been also reported, but the possible adverse effects, such as disturbance of the indigenous microbiota or resistance induction, should be taken into consideration, and thus the use of probiotics emerges as a possible alternative option of treatment. In this study, the oral administration of Bifidobacterium longum subsp. infantis BB-02 was evaluated as a preventive strategy for acute experimental UC induced in female BALB/c mice by ingestion of 3.5% dextran sulphate sodium in drinking water during 7 days. During this time, the daily disease activity index was evaluated, and on the seventh day the animals were euthanised to collect intestines and liver for analysis. Treatment with the probiotic resulted in clinical improvement of the animals. The histological and morphometric analyses showed a reduction of lesions and oedema in the gut, but there was no increase in the production of mucin. The dosage of secretory immunoglobulin A was significantly higher in the colitis group and reduced in the group treated with the probiotic. There was also a reduction in the inflammation of the colon, as demonstrated by a decrease in neutrophils infiltration, and KC/CXCL-1 levels. The intestinal permeability, which is typically increased during the onset of IBD, was also reduced by treatment with probiotic. Based on these data, it can be concluded that the bacterium B. infantis BB-02 has a probiotic potential for the attenuation of UC, but further studies should be conducted to verify the mechanism of protective action of the bacterium.

Orally administered extract from Prunella vulgaris attenuates spontaneous colitis in mdr1a-/- mice

AIM: To investigate the ability of a Prunella vulgaris (P. vulgaris) ethanolic extract to attenuate spontaneous typhlocolitis in mdr1a^-/- mice.

METHODS: Vehicle (5% ethanol) or P. vulgaris ethanolic extract (2.4 mg/d) were administered daily by oral gavage to mdr1a^-/- or wild type FVB^WT mice from 6 wk of age up to 20 wk of age. Clinical signs of disease were noted by monitoring weight loss. Mice experiencing weight loss in excess of 15% were removed from the study. At the time mice were removed from the study, blood and colon tissue were collected for analyses that included histological evaluation of lesions, inflammatory cytokine levels, and myeloperoxidase activity.

RESULTS: Administration of P. vulgaris extracts to mdr1a^-/- mice delayed onset of colitis and reduced severity of mucosal inflammation when compared to vehicle-treated mdr1a^-/- mice. Oral administration of the P. vulgaris extract resulted in reduced (P < 0.05) serum levels of IL-10 (4.6 ± 2 vs 19.4 ± 4), CXCL9 (1319.0 ± 277 vs 3901.0 ± 858), and TNFα (9.9 ± 3 vs 14.8 ± 1) as well as reduced gene expression by more than two-fold for Ccl2, Ccl20, Cxcl1, Cxcl9, IL-1α, Mmp10, VCAM-1, ICAM, IL-2, and TNFα in the colonic mucosa of mdr1a^-/- mice compared to vehicle-treated mdr1a^-/- mice. Histologically, several microscopic parameters were reduced (P < 0.05) in P. vulgaris-treated mdr1a^-/- mice, as was myeloperoxidase activity in the colon (2.49 ± 0.16 vs 3.36 ± 0.06, P < 0.05). The numbers of CD4⁺ T cells (2031.9 ± 412.1 vs 5054.5 ± 809.5) and germinal center B cells (2749.6 ± 473.7 vs 4934.0 ± 645.9) observed in the cecal tonsils of P. vulgaris-treated mdr1a^-/- were significantly reduced (P < 0.05) from vehicle-treated mdr1a^-/- mice. Vehicle-treated mdr1a^-/- mice were found to produce serum antibodies to antigens derived from members of the intestinal microbiota, indicative of severe colitis and a loss of adaptive tolerance to the members of the microbiota. These serum antibodies were greatly reduced or absent in P. vulgaris-treated mdr1a^-/- mice.

CONCLUSION: The anti-inflammatory activity of P. vulgaris ethanolic extract effectively attenuated the severity of intestinal inflammation in mdr1a^-/- mice.

S100A12 concentrations and myeloperoxidase activity in the intestinal mucosa of healthy dogs

BACKGROUND

Relatively few laboratory markers have been evaluated for the detection or monitoring of intestinal inflammation in canine chronic enteropathies, including inflammatory bowel disease (IBD). Previous research found that the intestinal mucosal levels of S100A12 and myeloperoxidase (MPO), as biomarkers of gut inflammation, were elevated in human patients with IBD. To date, the S100A12 and MPO levels in intestinal mucosal samples from either healthy dogs or from dogs suffering from IBD remain unreported. Therefore, this study aimed to evaluate the mucosal S100A12 and MPO levels in four different parts of the intestine (duodenum, jejunum, ileum and colon) in 12 healthy laboratory Beagle dogs using the ELISA and spectrophotometric methods, respectively.

RESULTS

Based on histological examinations, the recorded findings for all the samples were considered normal. The mucosal concentration of S100A12 in the ileum was significantly higher than in all other segments of the intestine (p < 0.05). MPO activity was significantly higher in the ileal, jejunal and duodenal than in colonic mucosal samples (p < 0.05). Moreover, its concentration was higher in the jejunum than in the duodenum.

CONCLUSIONS

This study showed that S100A12 and MPO are reliably detectable in canine intestinal mucosa. The assays used appeared to be sufficient to further evaluate the role of S100A12 and MPO in the pathogenesis of canine chronic enteropathies, including IBD. These biomarkers may play a role in the initial detection of gut inflammation suggesting the need for further investigations to confirm IBD or to differentiate between IBD subtypes. Understanding the role of S100A12 and MPO in the pathogenesis of chronic intestinal inflammation in future may result in an improved understanding of canine chronic intestinal inflammation.

Suppression of dextran sulfate sodium-induced colitis in mice by radon inhalation

The enhanced release of reactive oxygen species from activated neutrophils plays important role in the pathogenesis of inflammatory bowel disease. We previously reported that radon inhalation activates antioxidative functions in various organs of mice. In this study, we examined the protective effects of radon inhalation on dextran sulfate sodium- (DSS) induced colitis in mice which were subjected to DSS for 7 days. Mice were continuously treated with air only (sham) or radon at a concentration of 2000 Bq/m³ from a day before DSS administration to the end of colitis induction. In the results, radon inhalation suppressed the elevation of the disease activity index score and histological damage score induced by DSS. Based on the changes in tumor necrosis factor-alpha in plasma and myeloperoxidase activity in the colon, it was shown that radon inhalation suppressed DSS-induced colonic inflammation. Moreover, radon inhalation suppressed lipid peroxidation of the colon induced by DSS. The antioxidant level (superoxide dismutase and total glutathione) in the colon after DSS administration was significantly higher in mice treated with radon than with the sham. These results suggested that radon inhalation suppressed DSS-induced colitis through the enhancement of antioxidative functions in the colon.

Cells, cytokines and inflammatory bowel disease: a clinical perspective

Ulcerative colitis and Crohn's disease are chronic inflammatory disorders of the GI tract. Although the disorders can usually be distinguished on clinical and pathological criteria, there are similarities in natural history and response to therapy. The purpose of this article is to examine the inflammatory infiltrate in both disorders and the cytokine profiles in intestinal mucosa and peripheral blood. For both disorders, the predominant cells in inflamed mucosa are neutrophils and lymphocytes positive for CD4. There are also increases in the number of B cells, macrophages, dendritic cells, plasma cells, eosinophils and perhaps mast cells. Cytokine levels and cytokine expression are also similar for both disorders, with increases in TNF-α and IFN-γ consistent with a Th1 response. As inflammation occurs in a microbial environment, one possibility is that the nature of the inflammatory response is largely independent of initiating factors. One concept that might be useful is that of initiating cells and cytokines and effector cells and cytokines. Persuasive evidence exists for a defect in phagocytic cells in Crohn's disease, perhaps with the expansion of a subset of activated macrophages. There are also possible links to natural killer cells and changes in the regulation of IL-8 and perhaps IL-22. For ulcerative colitis, the cellular events are less clear, but natural killer T cells may be important as initiating cells, and there is some evidence for upregulation of cytokines involved in Th2 responses, including IL-4 and IL-13. For both disorders, proinflammatory cytokines include TNF-α, IL-12, IL-23, and perhaps IL-17 and IFN-γ. Research challenges include the identification, activation and function of subsets of inflammatory cells, as well as new ways to terminate the inflammatory response.

Epithelial barriers in intestinal inflammation

The gastrointestinal epithelium transports solutes and water between lumen and blood and at the same time forms a barrier between these compartments. This highly selective and regulated barrier permits ions, water, and nutrients to be absorbed, but normally restricts the passage of harmful molecules, bacteria, viruses and other pathogens. During inflammation, the intestinal barrier can be disrupted, indicated by a decrease in transcellular electrical resistance and an increase in paracellular permeability for tracers of different size. Such inflammatory processes are accompanied by increased oxidative stress, which in turn can impair the epithelial barrier. In this review, we discuss the role of inflammatory oxidative stress on barrier function with special attention on the epithelial tight junctions. Diseases discussed causing barrier changes include the inflammatory bowel diseases Crohn's disease, ulcerative colitis, and microscopic colitis, the autoimmune disorder celiac disease, and gastrointestinal infections. In addition, the main cytokines responsible for these effects and their role during oxidative stress and intestinal inflammation will be discussed, as well as therapeutic approaches and their mode of action.

Neutrophil-dependent oxidative stress in ulcerative colitis

Neutrophil accumulation within epithelial crypts and in the intestinal mucosa directly correlates with clinical disease activity and epithelial injury in ulcerative colitis (UC). Current advances have defined the mechanisms by which neutrophils are activated or migrate across mucosal epithelia. A better understanding of this process will likely provide new insights into novel treatment strategies for UC. Especially, activated neutrophils produce reactive oxygen and nitrogen species within intestinal mucosa, which induce oxidative stress. In clinically, we have succeeded to develop a novel granulocytes adsorptive apheresis therapy for UC. In this article, we discuss current advances to define the role of neutrophils-dependent oxidative stress in UC.

Modulation of neutrophil motility by curcumin: implications for inflammatory bowel disease

BACKGROUND

Neutrophils (PMN) are the first cells recruited at the site of inflammation. They play a key role in the innate immune response by recognizing, ingesting, and eliminating pathogens and participate in the orientation of the adaptive immune responses. However, in inflammatory bowel disease (IBD) transepithelial neutrophil migration leads to an impaired epithelial barrier function, perpetuation of inflammation, and tissue destruction via oxidative and proteolytic damage. Curcumin (diferulolylmethane) displays a protective role in mouse models of IBD and in human ulcerative colitis, a phenomenon consistently accompanied by a reduced mucosal neutrophil infiltration.

METHODS

We investigated the effect of curcumin on mouse and human neutrophil polarization and motility in vitro and in vivo.

RESULTS

Curcumin attenuated lipopolysaccharide (LPS)-stimulated expression and secretion of macrophage inflammatory protein (MIP)-2, interleukin (IL)-1β, keratinocyte chemoattractant (KC), and MIP-1α in colonic epithelial cells (CECs) and in macrophages. Curcumin significantly inhibited PMN chemotaxis against MIP-2, KC, or against conditioned media from LPS-treated macrophages or CEC, a well as the IL-8-mediated chemotaxis of human neutrophils. At nontoxic concentrations, curcumin inhibited random neutrophil migration, suggesting a direct effect on neutrophil chemokinesis. Curcumin-mediated inhibition of PMN motility could be attributed to a downregulation of PI3K activity, AKT phosphorylation, and F-actin polymerization at the leading edge. The inhibitory effect of curcumin on neutrophil motility was further demonstrated in vivo in a model of aseptic peritonitis.

CONCLUSIONS

Our results indicate that curcumin interferes with colonic inflammation partly through inhibition of the chemokine expression and through direct inhibition of neutrophil chemotaxis and chemokinesis.

Treatment with a novel chemokine-binding protein or eosinophil lineage-ablation protects mice from experimental colitis

Eosinophils are multifunctional leukocytes implicated in numerous inflammatory diseases. The present study was conducted to clarify the precise role of eosinophils in the development of colitis by using eosinophil-depleted mice and a novel chemokine-binding protein that neutralizes CCL11 action. Colitis was induced by administration of dextran sodium sulfate (DSS) to wild-type and eosinophil-deficient DeltadblGATA-1 mice. Accumulation of eosinophils in the gut of mice given DSS paralleled worsening of clinical score and weight loss. In response to DSS, DeltadblGATA-1 mice showed virtual absence of eosinophil recruitment, amelioration of clinical score, weight loss, and tissue destruction, and no lethality. There was a decrease in CXCL1 and CCL3 production and decreased neutrophil influx in the intestine of DeltadblGATA-1 mice. Transfer of bone marrow cells from wild-type mice reconstituted disease manifestation in DSS-treated DeltadblGATA-1 mice, and levels of CCL11 were increased after DSS treatment and localized to inflammatory cells. Treatment with the chemokine-binding protein evasin-4 at a dose that prevented the function of CCL11 greatly ameliorated clinical score, weight loss, overall tissue destruction, and death rates. In conclusion, the influx of eosinophils is critical for the induction of colitis by DSS. Treatment with a novel chemokine-binding protein decreased eosinophil influx and greatly ameliorated colitis, suggesting that strategies that interfere with the recruitment of eosinophils may be useful as therapy for colitis.

The selective nonpeptide CXCR2 antagonist SB225002 ameliorates acute experimental colitis in mice

Although neutrophils are strongly implicated in eliminating pathogens, excessive recruitment may cause tissue damage. Therefore, reducing cell influx during an inflammatory process may be a potential target for treating inflammatory bowel diseases (IBD). As CXCR2 is involved in neutrophil migration, this study aimed to evaluate whether the systemic therapeutic treatment with selective CXCR2 antagonist SB225002 ameliorates experimental colitis, which was induced in mice by 2,4,6-trinitrobenzene sulfonic acid (TNBS). After colitis establishment (24 h), mice were treated with SB225002. At later time-points, up to 72 h, mice were monitored for body weight loss and overall mortality. At the time of sacrifice, colonic tissues were scored for macro- and microscopic damage, and cytokine levels, myeloperoxidase (MPO) activity, and protein expression were analyzed. TNBS administration induced macro- and microscopic damage in colon tissue, leading in most cases to animal death. Curative treatment with SB225002 significantly reduced all of the parameters analyzed, leading to an improvement of inflammatory signs. SB225002 reduced neutrophil influx, MPO activity, IL-1beta, MIP-2, and keratinocyte-derived chemokine (KC) levels and the expression of vascular endothelial growth factor, inducible NO synthase, and cyclooxygenase-2 proteins into the colon tissue. Levels of IL-4 and IL-10 were increased significantly in the colons of animals treated with SB225002. Additionally, curative treatment with mouse anti-KC significantly reduced MPO activity and colonic damage. These results taken together demonstrate that a selective blockade of CXCR2 consistently reduced TNBS-induced colitis, suggesting that the use of SB225002 is a potential therapeutic approach for the treatment of IBD and other related inflammatory disorders.

TRPM2-mediated Ca2+influx induces chemokine production in monocytes that aggravates inflammatory neutrophil infiltration

Reactive oxygen species (ROS) induce chemokines responsible for the recruitment of inflammatory cells to sites of injury or infection. Here we show that the plasma membrane Ca(2+)-permeable channel TRPM2 controls ROS-induced chemokine production in monocytes. In human U937 monocytes, hydrogen peroxide (H(2)O(2)) evokes Ca(2+) influx through TRPM2 to activate Ca(2+)-dependent tyrosine kinase Pyk2 and amplify Erk signaling via Ras GTPase. This elicits nuclear translocation of nuclear factor-kappaB essential for the production of the chemokine interleukin-8 (CXCL8). In monocytes from Trpm2-deficient mice, H(2)O(2)-induced Ca(2+) influx and production of the macrophage inflammatory protein-2 (CXCL2), the mouse CXCL8 functional homolog, were impaired. In the dextran sulfate sodium-induced colitis inflammation model, CXCL2 expression, neutrophil infiltration and ulceration were attenuated by Trpm2 disruption. Thus, TRPM2 Ca(2+) influx controls the ROS-induced signaling cascade responsible for chemokine production, which aggravates inflammation. We propose functional inhibition of TRPM2 channels as a new therapeutic strategy for treating inflammatory diseases.

Molecular fingerprints of neutrophil-dependent oxidative stress in inflammatory bowel disease

Neutrophil accumulation within epithelial crypts and in the intestinal mucosa directly correlates with clinical disease activity and epithelial injury in inflammatory bowel disease (IBD). Current advances have defined the mechanisms by which neutrophils are activated or migrate across endothelial and mucosal epithelial cells. A better understanding of this process will likely provide new insights into novel treatment strategies for IBD. Especially, activated neutrophils produce reactive oxygen and nitrogen species and myeloperoxidase within intestinal mucosa, which induce oxidative stress. Posttranslational modification of proteins generated by these reactive species serves as a "molecular fingerprint" of protein modification by lipid peroxidation-, nitric oxide-, and myeloperoxidase-derived oxidants. Measurement of these modified proteins may serve both as a quantitative index of oxidative stress and an important new biological marker of clinical relevance to IBD. We have succeeded in the clinical development of a novel granulocyte adsorptive apheresis therapy for IBD. In this review, we discuss current advances in defining the role of neutrophil-dependent oxidative stress in IBD.

Recent advances in basic and clinical aspects of inflammatory bowel disease: Which steps in the mucosal inflammation should we block for the treatment of inflammatory bowel disease?

There are four steps in the interaction between intestinal microbes and mucosal inflammation in genetically predisposed individuals from the viewpoints of basic and clinical aspects of inflammatory bowel disease (IBD). The first step is an interaction between intestinal microbes or their components and intestinal epithelial cells via receptors, the second step an interaction between macrophages and dendritic cells and mucosal lymphocytes, the third step an interaction between lymphocytes and vascular endothelial cells, and the fourth step an interaction between lymphocytes and granulocytes producing proinflammatory cytokines or free radicals and mucosal damage and repair. Recent therapeutic approaches for IBD aim to block these four steps in the intestinal inflammation of patients with IBD.

Critical role of MCP-1 in the pathogenesis of experimental colitis in the context of immune and enterochromaffin cells

Mucosal changes in inflammatory bowel disease (IBD) are characterized by ulcerative lesions accompanied by a prominent infiltrate of inflammatory cells including lymphocytes, macrophages, and neutrophils and alterations in 5-hydroxytryptamine (5-HT)-producing enterochromaffin (EC) cells. Mechanisms involved in recruiting and activating these cells are thought to involve a complex interplay of inflammatory mediators. Studies in clinical and experimental IBD have shown the upregulation of various chemokines including monocyte chemoattractant protein (MCP)-1 in mucosal tissues. However, precise information on the roles of this chemokine or the mechanisms by which it takes part in the pathogenesis of IBD are not clear. In this study, we investigated the role of MCP-1 in the development of hapten-induced experimental colitis in mice deficient in MCP-1. Our results showed a significant reduction in the severity of colitis both macroscopically and histologically along with a decrease in mortality in MCP-1-deficient mice compared with wild-type control mice. This was correlated with a downregulation of myeloperoxidase activity, IL-1beta, IL-12p40, and IFN-gamma production, and infiltration of CD3+ T cells and macrophages in the colonic mucosa. In addition, we observed significantly lower numbers of 5-HT-expressing EC cells in the colon of MCP-1-deficient mice compared with those in wild-type mice after dinitrobenzenesulfonic acid. These results provide evidence for a critical role of MCP-1 in the development of colonic inflammation in this model in the context of immune and enteric endocrine cells.

Functional and biochemical characterization of epithelial bactericidal/permeability-increasing protein

Epithelial cells of many mucosal organs have adapted to coexist with microbes and microbial products. In general, most studies suggest that epithelial cells benefit from interactions with commensal microorganisms present at the lumenal surface. However, potentially injurious molecules found in this microenvironment also have the capacity to elicit local inflammatory responses and even systemic disease. We have recently demonstrated that epithelia cells express the anti-infective molecule bactericidal/permeability-increasing protein (BPI). Here, we extend these findings to examine molecular mechanisms of intestinal epithelial cell (IEC) BPI expression and function. Initial experiments revealed a variance of BPI mRNA and protein expression among various IEC lines. Studies of BPI promoter expression in IECs identified regulatory regions of the BPI promoter and revealed a prominent role for CCAAT/enhancer binding protein and especially Sp1/Sp3 in the basal regulation of BPI. To assess the functional significance of this protein, we generated an IEC line stably transfected with full-length BPI. We demonstrated that, whereas epithelia express markedly less BPI protein than neutrophils, epithelial BPI contributes significantly to bacterial killing and attenuating bacterial-elicted proinflammatory signals. Additional studies in murine tissue ex vivo revealed that BPI is diffusely expressed along the crypt-villous axis and that epithelial BPI levels decrease along the length of the intestine. Taken together, these data confirm the transcriptional regulation of BPI in intestinal epithelia and provide insight into the relevance of BPI as an anti-infective molecule at intestinal surfaces.

Leukocytapheresis is effective in inducing but not in maintaining remission in ulcerative colitis

GOALS AND BACKGROUND

Ulcerative colitis (UC) is a chronic inflammatory bowel disease characterized by dense infiltration of lymphocytes, plasma cells, neutrophils, and monocyte-macrophages into the colonic mucosa. Leukocytapheresis is a procedure for selectively removing white blood cells from withdrawn blood. It is used for the treatment of several autoimmune diseases. This study was performed to evaluate the effectiveness of leukocytapheresis for inducing and maintaining remission in corticosteroid-resistant UC, as compared with corticosteroid-responsive UC.

STUDY

Forty-five patients with active UC who were treated with a dose of 1 mg/kg per day or more of prednisolone given systemically for at least 2 weeks were evaluated. Twenty patients (6 males, 14 females) in whom improvement was induced only by high doses of prednisolone were allocated as the corticosteroid-responsive group. The other 25 patients (11 males, 14 females) who did not respond to the above-mentioned dose of prednisolone therapy were allocated as the corticosteroid-resistant group and received leukocytapheresis therapy once a week for 5 weeks. Of patients who had a remission, the corticosteroid-responsive group continued to have the conventional therapy and the corticosteroid-resistant group were given leukocytapheresis once every 4 weeks for at least 2 years as maintenance therapy.

RESULTS

Remission was induced by 5 weeks of leukocytapheresis in 23 of the 25 (92%) patients with corticosteroid-resistant active UC. The number of days required to achieve remission of UC was fewer in patients who received leukocytapheresis than in those who did not. Follow-up study of the patients who had remission showed similar relapse rates at 2 years in the patients who received leukocytapheresis and those given high doses of prednisolone alone.

CONCLUSIONS

Leukocytapheresis is an effective treatment of acute corticosteroid-resistant UC but does not prevent the recurrence of UC.

The role of CCL3/macrophage inflammatory protein-1α in experimental colitis

CCL3/macrophage inflammatory protein (MIP-1)-1alpha is elevated in the rectal biopsies of patients with active inflammatory bowel diseases, but its role remains undefined. The present study examined the role of CCL3/MIP-1alpha during trinitrobenzene sulfonic acid (TNBS)-induced colitis in the rat. Colonic CCL3/MIP-1alpha levels were elevated (>20-fold above control) within 24 h and remained elevated to day 7 of colitis induction by TNBS administration. In addition, significant increases in colonic neutrophil accumulation were observed within 24 h to day 7 of TNBS treatment. Pre-treatment of rats with a single dose of CCL3/MIP-1alpha antibody significantly reduced (47%) colonic neutrophil accumulation during the early (24 h) phase of TNBS-induced colitis. In contrast, chronic (repeated) administration of CCL3/MIP-1alpha antibody did not attenuate colonic neutrophil accumulation during the late phase (day 7) of TNBS-induced colitis. These results suggest a role for CCL3/MIP-1alpha in promoting colonic neutrophil accumulation during the early (24 h) phase of TNBS-induced colitis.

Contrasting roles for CXCR2 during experimental colitis

Neutrophil recruitment into the colon is believed to play a crucial pathogenic role in the progression of clinical and experimental inflammatory bowel diseases (IBDs). The chemokine receptor CXCR2 is highly expressed on neutrophils, and promotes neutrophil recruitment in several inflammatory diseases. The present study determined the biological role of CXCR2 during trinitrobenzene sulfonic acid (TNBS)-induced colitis in the rat by assessing effects of CXCR2 antibody neutralization on neutrophil accumulation during the early (8 h) and late phase (day 7) of TNBS-induced colitis. CXCR2 expression was elevated (>3-fold above control) within 8 h and remained elevated to day 7 of colitis induction, in parallel with significant increases in neutrophil infiltration. Treatment of colitic rats with a single dose of CXCR2 neutralizing antibody significantly reduced colonic neutrophil accumulation during the early (8 h) phase of TNBS-induced colitis. However, chronic administration of CXCR2 antibody did not reduce colonic neutrophil accumulation during the late phase (day 7) of TNBS-induced colitis. In summary, the present findings suggest a functional role for CXCR2 in initiating neutrophil recruitment during the early phase of TNBS-induced acute colitis, and demonstrate that: early colonic neutrophil accumulation is CXCR2 dependent and the late phase colonic neutrophil accumulation is CXCR2 independent.

Mediators of Inflammation in Children with Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) in children remains a challenging problem. Crohn disease and ulcerative colitis are characterized by an activation of intestinal mononuclear cells and T-cells within the inflammed lesions. In the present study, we determined whether circulating inflammatory mediators, such as interleukins and adhesion molecules, may represent useful markers of immune activation in vivo. Serum concentrations of IL-2, IL-6, IL-8, IL-10, sIL-2R, sICAM-1 and sVCAM-1 were measured by a quantitative enzyme-linked immunosorbent assay (ELISA) in 18 patients with IBD and 25 healthy subjects matched for age and sex (control group). According to our results, all the inflammatory mediators are significantly increased in patients with IBD as compared to the control group. Pro-inflammatory mediators (IL-6, IL-8, IL-10) are elevated in the serum of patients with active disease, suggesting that they act as naturally occuring initiators of the acute inflammatory process. Increased IL-2 and sIL-2R levels reflect T-cell activation. Increased circulating sICAM-1 and sVCAM-1 levels may reflect increased adhesiveness and signal transmission across cells, probably as a result of shedding of the parent molecule during local cellular immunoresponses in vivo. The measurement of inflammatory mediators may be a useful adjunct to the clinical assessment and to the routine laboratory testing of IBD pediatric patients.

Role of chemokines and chemokine receptors in the gastrointestinal tract

The pathological association between leucocytes and gastrointestinal diseases has long been recognized. Chemokines are a large family of chemotactic cytokines whose fundamental role is the recruitment of leucocytes to tissues. Although chemokines and their receptors are considered to be mediators of inflammation and tissue injury in several inflammatory diseases, their precise role in the pathophysiology of gastrointestinal diseases remains incompletely understood. Nonetheless, by virtue of their expression and localization at sites of gastrointestinal tissue injury and inflammation, a number of investigators have suggested a vital role for chemokines and their receptors in the pathophysiology of gastrointestinal diseases. This short review examines the role of chemokines and their receptors in the gastrointestinal tract with an emphasis on their involvement in the regulation of intestinal and hepatic inflammation.

Interleukin-8 increases acetylcholine response of rat intestinal segments

BACKGROUND

Interleukin-8 (IL-8) is a pro-inflammatory cytokine highly expressed in inflammatory bowel diseases, but whose effects on intestinal motility are unknown.

AIM

To characterize the role of IL-8 in the contraction of rat intestinal segments.

METHODS

Contractile response to acetylcholine (ACh 10-6 M) in terminal ileal segments (including mucosa) from Wistar rats was measured before and after incubation (15, 30, 60 or 90 min) with IL-8 (1 ng/mL), and after 60 min of incubation with different doses of IL-8 (0, 0.1, 0.5, 1, 10 and 100 ng/mL). The effects of blocking neural transmission with tetrodotoxin (TTX) and inhibiting protein synthesis (cycloheximide) were tested. The contractile response of longitudinal muscle-myenteric plexus preparations (i.e. without mucosa) was measured after 60 min of incubation with 0.1 and 1 ng/mL of IL-8.

RESULTS

IL-8 increased ileal contraction induced by ACh 10(-6) M. This augmentation was significant after 60 min of incubation (58%, P=0.01) and persisted after 90 min (18%, P=0.04). A 60-min incubation period showed a dose-related effect, beginning at 0.5 ng/mL (30%, P=0.003) and reaching a peak at 1 ng/mL (58%, P=0.01). The same effect was also observed on colonic segments. TTX did not affect the IL-8 increase of ACh-induced contractions, which was completely abolished by cycloheximide. IL-8 had no significant effect on longitudinal muscle-myenteric plexus preparations.

CONCLUSION

In vitro, IL-8 increases contractile response of the ileum to ACh in a dose-dependent manner. This effect is not neurally mediated, but seems to involve protein synthesis by intestinal mucosa.

Neutrophil and eosinophil granule proteins as markers of response to local prednisolone treatment in distal ulcerative colitis and proctitis

OBJECTIVE

The pathophysiological role of neutrophil and eosinophil granulocytes in relation to steroid enema treatment was studied in patients with distal ulcerative colitis and proctitis.

METHODS

The rectal release of the neutrophil (myeloperoxidase, MPO), and eosinophil (eosinophilic cationic protein, ECP and eosinophil peroxidase, EPO) granule constituents were measured in 11 patients using intraluminal segmental perfusion of the rectum. The released amounts of MPO, ECP, and EPO in the perfusion fluids were determined by radioimmunoassays before and during prednisolone enema treatment and related to clinical, endoscopical, and histopathological data in addition to treatment outcome.

RESULTS

Clinical activity and particularly endoscopic activity correlated well with intraluminal MPO concentrations both before and during treatment. At the end of the study, eight of 11 patients fulfilled predefined response criteria; all responding patients had significant decrease of MPO concentrations (p < 0.01). This decline of MPO concentration was seen after 7 days of treatment (p < 0.05) in the response group and often occurred before clinical improvement. There was a nonsignificant trend toward a decrease in the concentrations of ECP and EPO at the end of treatment in responders.

Gut-associated lymphoid tissues in ulcerative colitis

BACKGROUND

The main feature of ulcerative colitis (UC) is numerous infiltration of not only lymphocytes and plasma cells but also neutrophils and macrophages, indicating acute on chronic inflammation. Recent studies show that apoptosis may play an important role in the regulation of gut-associated lymphoid tissues (GALT). Therefore, this study was performed to clarify apoptosis of lymphocytes in the peripheral blood and colonic mucosa of UC.

METHODS

Three-color flow cytometry was used to clarify apoptosis of lymphocytes in the peripheral blood and colonic mucosa of patients with active and inactive UC compared with controls using fluorescence-labeled monoclonal and polyclonal antibodies such as Fas (CD95), Fas ligand, CD4, CD8, CD45RO, etc.

RESULTS

The ratio of Fas and CD45RO double-positive cells in the peripheral blood of UC patients was significantly increased in CD8 but not CD4 T cells when compared with controls. The ratio of Fas-positive and CD45RO-negative cells was significantly increased in CD4 and CD8 T cells of UC when compared with controls. There was unbalanced immunoregulation between CD4 and CD8 T cells in the colonic mucosa of UC probably due to apoptosis through Fas-Fas ligand system.

CONCLUSIONS

Abnormal GALT system was found in UC probably due to dysregulation of T cells through Fas-Fas ligand system.

Local and systemic delivery of a stable aspirin-triggered lipoxin prevents neutrophil recruitment in vivo

Aspirin (ASA) triggers a switch in the biosynthesis of lipid mediators, inhibiting prostanoid production and initiating 15-epi-lipoxin generation through the acetylation of cyclooxygenase II. These aspirin-triggered lipoxins (ATL) may mediate some of ASA's beneficial actions and therefore are of interest in the search for novel antiinflammatories that could manifest fewer unwanted side effects. Here, we report that design modifications to native ATL structure prolong its biostability in vivo. In mouse whole blood, ATL analogs protected at carbon 15 [15(R/S)-methyl-lipoxin A4 (ATLa1)] and the omega end [15-epi-16-(para-fluoro)-phenoxy-LXA4 (ATLa2)] were recoverable to approximately 90 and 100% at 3 hr, respectively, compared with a approximately 40% loss of native lipoxin A4. ATLa2 retains bioactivity and, at levels as low as approximately 24 nmol/mouse, potently inhibited tumor necrosis factor-alpha-induced leukocyte recruitment into the dorsal air pouch. Inhibition was evident by either local intra-air pouch delivery (approximately 77% inhibition) or systemic delivery by intravenous injection (approximately 85% inhibition) and proved more potent than local delivery of ASA. Rank order for inhibiting polymorphonuclear leukocyte infiltration was: ATLa2 (10 micrograms, i.v.) approximately ATLa2 (10 micrograms, local) approximately dexamethasone (10 micrograms, local) >ASA (1.0 mg, local). Applied topically to mouse ear skin, ATLa2 also inhibited polymorphonuclear leukocyte infiltration induced by leukotriene B4 (approximately 78% inhibition) or phorbol ester (approximately 49% inhibition), which initiates endogenous chemokine production. These results indicate that this fluorinated analog of natural aspirin-triggered lipoxin A4 is bioavailable by either local or systemic delivery routes and is a more potent and precise inhibitor of neutrophil accumulation than is ASA.