The correlation between proinflammatory cytokines, MAdCAM-1 and cellular infiltration in the inflamed colon from TNF-alpha gene knockout mice

The bidirectional relationship of depression and disturbances in B cell homeostasis: Double trouble

Major depressive disorder (MDD) is a recurrent, persistent, and debilitating neuropsychiatric syndrome with an increasing morbidity and mortality, representing the leading cause of disability worldwide. The dysregulation of immune systems (including innate and adaptive immune systems) has been identified as one of the key contributing factors in the progression of MDD. As the main force of the humoral immunity, B cells have an essential role in the defense against infections, antitumor immunity and autoimmune diseases. Several recent studies have suggested an intriguing connection between disturbances in B cell homeostasis and the pathogenesis of MDD, however, the B-cell-dependent mechanism of MDD remains largely unexplored compared to other immune cells. In this review, we provide an overview of how B cell abnormality regulates the progression of MMD and the potential consequence of the disruption of B cell homeostasis in patients with MDD. Abnormalities of B-cell homeostasis not only promote susceptibility to MDD, but also lead to an increased risk of developing infection, malignancy and autoimmune diseases in patients with MDD. A better understanding of the contribution of B cells underlying MDD would provide opportunities for identification of more targeted treatment approaches and might provide an overall therapeutic benefit to improve the long-term outcomes of patients with MDD.

Mucosal addressin cell adhesion molecule 1 expression reflects mucosal inflammation and subsequent relapse in patients with ulcerative colitis

BACKGROUND AND AIMS

Mucosal addressin cell adhesion molecule 1 (MAdCAM-1) is upregulated in the vascular endothelium of the colonic mucosa in ulcerative colitis (UC). Although the association between MAdCAM-1 expression and mucosal inflammation has been discussed, the association with the clinical course of UC patients has not been reported. In this study we investigated not only the association between mucosal MAdCAM-1 expression and mucosal inflammation, but also its association with subsequent relapse in UC patients with clinical remission.

METHODS

Eighty UC patients in remission who visited Kyoto Prefectural University of Medicine for follow-up for 2 years were included. Biopsy samples were collected during colonoscopy, and transcriptional expression levels of UC-related cytokines and MAdCAM-1 were quantified using real-time polymerase chain reaction. MAdCAM-1 mRNA expression and protein expression by immunohistochemistry was compared in patients who subsequently relapsed and those who remained in remission and examined in relation to endoscopic findings, histologic activity, and cytokine expression.

RESULTS

MAdCAM-1 expression was correlated with endoscopic severity, and significantly elevated in histological active mucosa than inactive mucosa. Furthermore, MAdCAM-1 expression levels were closely correlated with those of several cytokines. MAdCAM-1 mRNA and protein expression were significantly higher in the relapse group than in the remission group, indicating that MAdCAM-1 expression in the mucosa is already elevated in UC patients in clinical remission who subsequently relapse.

CONCLUSIONS

MAdCAM-1 expression in the colonic mucosa of UC patients related to mucosal inflammation and subsequent relapse; it may serve as a marker for both relapse and therapeutic effectiveness in UC.

Crocetin Prolongs Recovery Period of DSS-Induced Colitis via Altering Intestinal Microbiome and Increasing Intestinal Permeability

Crocetin is one of the major active constituents of saffron (Crocus sativus L.) which has a reputation for facilitating blood circulation and dispersing blood stasis in traditional Chinese medicine. However, there is little evidence showing the relationship between crocetin intake and the risk of gastrointestinal diseases such as colitis. In order to investigate the effect of crocetin on the regulation of intestinal barrier function and intestinal microbiota composition, mice were treated with crocetin after 3% dextran sulfate sodium (DSS) administration for one week. We found that crocetin intake at 10 mg/kg aggravated colitis in mice, showing increased weight loss and more serious histological abnormalities compared with the DSS group. The 16s rDNA sequencing analysis of the feces samples showed that mice treated with 10 mg/kg crocetin had lower species diversity and richness than those treated with DSS. At the genus level, a higher abundance of Akkermansia and Mediterraneibacter, and a lower abundance of Muribaculaceae, Dubosiella, Paramuribaculum, Parasutterella, Allobaculum, Duncaniella, Candidatus Stoquefichus, and Coriobacteriaceae UCG-002 were observed in the crocetin group. Untargeted metabolomic analyses revealed that crocetin reduced the levels of primary and secondary bile acids such as 12-ketodeoxycholic acid, 7-ketodeoxycholic acid, 3-sulfodeoxycholic acid, 6-ethylchenodeoxycholic acid, chenodeoxycholate, glycochenodeoxycholate-7-sulfate, glycocholate, and sulfolithocholic acid in the colon. In conclusion, crocetin intake disturbed intestinal homeostasis and prolonged recovery of colitis by promoting inflammation and altering gut microbiota composition and its metabolic products in mice. Our findings suggest that patients with gastrointestinal diseases such as inflammatory bowel disease should use crocetin with caution.

Chronic Exposure to Continuous Brightness or Darkness Modulates Immune Responses and Ameliorates the Antioxidant Enzyme System in Male Rats

Circadian rhythms are considered vital regulators of immune functions. This study aims to elucidate the effects of chronic circadian disruption on immune functions, clock genes expression, and antioxidant enzymes levels in lymphoid tissues. Adult male Sprague-Dawley rats were subjected to a normal light/dark cycle or either continuous light (LL) or continuous dark (DD) for 8 weeks. The results demonstrated (1) significant decreases in the circulating levels of interleukin 1β, interleukin 6 and tumor necrosis factor alpha (TNF-α) and significant increases in the levels of interleukin 10, interleukin 12, C-reactive protein (CRP) and corticosterone in both LL and DD groups; (2) upregulation in mRNA expression of core clock genes Cry1, Cry2, Per1, Per2, and Per3 in the spleen of the DD group and downregulation in Cry1 and Cry2 genes in the LL group; (3) elevation of total antioxidant capacity (TAC), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), nitric oxide (NO) and the lipid peroxidation marker malondialdehyde (MDA) in the spleen, lymph node and bone marrow of both the LL and DD groups and decreases in the levels of the same markers in the thymus of the LL group; (4) decreased numbers of CD4⁺ and CD8⁺ cells in lymphoid tissues of both the LL and the DD groups; (5) reduced platelets count and suppressed immunoglobulin (IgM, IgE) in the LL and DD groups with marked erythropenia and leukocytosis in the DD group. Taken together, circadian misalignment leads to hematological disruptions, dysregulation of clock genes, and inflammatory mediators, which further enhances the antioxidant enzyme system that is crucial for an organism's adaptation to stresses.

Inflammation-induced JMJD2D promotes colitis recovery and colon tumorigenesis by activating Hedgehog signaling

Histone demethylase JMJD2D can promote gene expression by specifically demethylating H3K9me2/3. The role of JMJD2D in colitis and colitis-associated colorectal cancer (CRC) progression remains unclear. Here, we show that colonic JMJD2D is induced by TNFα during dextran sulfate sodium-induced colitis. JMJD2D-deficient mice exhibit more severe colon damage and defective colon regeneration due to impaired Hedgehog signaling activation after colitis. JMJD2D knockdown in CRC cells suppresses Hedgehog signaling, resulting in reduced CRC growth and metastasis. Mechanistically, JMJD2D promotes Hedgehog target gene expression through interacting with Gli2 to reduce H3K9me3 levels at the promoter. Clinically, JMJD2D expression is upregulated and positively correlated with Gli2 expression in human inflammatory bowel disease specimens and CRC specimens. The JMJD2D inhibitor 5-c-8HQ or aspirin synergizes with Hedgehog inhibitor vismodegib to inhibit CRC cell proliferation and tumorigenesis. Collectively, our findings unveil an essential role of JMJD2D in activating the processes of colonic protection, regeneration, and tumorigenesis.

Soluble Mucosal Addressin Cell Adhesion Molecule 1 and Retinoic Acid are Potential Tools for Therapeutic Drug Monitoring in Patients with Inflammatory Bowel Disease Treated with Vedolizumab: A Proof of Concept Study

BACKGROUND AND AIMS

Vedolizumab [VDZ], a humanized monoclonal antibody targeting α4β7 integrin, is effective in induction and maintenance therapy in patients with inflammatory bowel disease [IBD] who have not adequately responded to standard therapies, and high vedolizumab trough levels [VTLs] have been associated with clinical remission. The α4β7 integrin binds to endothelial MAdCAM-1 and is upregulated by retinoic acid [RA]. The aim of this study was to determine the relationships between soluble MAdCAM-1 [sMAdCAM-1] and RA concentrations during clinical remission with VDZ maintenance therapy.

METHODS

In a retrospective study performed in IBD patients treated with VDZ, we measured VTL, sMAdCAM-1 and RA concentrations.

RESULTS

Among the 62 included patients [38 Crohn's disease], 24 relapsed and 38 stayed in remission from Weeks 10 to 30 after VDZ initiation. During this maintenance therapy, the median values of VTLs and RA were 15.4 µg/mL and 0.97 ng/mL, respectively, whereas sMAdCAM-1 was undetectable [<0.41 ng/mL] in 67.3% of samples. The positive predictive value [PPV] of undetectable sMAdCAM-1 for clinical remission was 80.0%, with a corresponding sensitivity of 74.6%. On multivariate analysis, undetectable sMAdCAM-1 and high VTLs [>19 µg/mL] were independently associated with clinical remission [OR = 7.5, p = 0.006 and OR = 2.2, p = 0.045, respectively]. The combination of sMAdCAM-1 < 0.41 ng/mL and VTL > 19 µg/mL was the best pharmacokinetic profile, with a PPV of 95.2%. Median values of sMAdCAM-1 and RA were significantly higher [p = 0.0001] before VDZ therapy than during the follow-up [sMAdCAM-1: 40.5 vs < 0.41 ng/mL; RA: 1.7 vs 0.97 ng/mL]. Only RA > 1.86 ng/mL before VDZ therapy was predictive of clinical remission during the follow-up (Area Under a Receiver Operating Characteristic curve [AUROC] = 80.7%).

CONCLUSIONS

Undetectable sMAdCAM-1 appears strongly associated with clinical remission during VDZ maintenance therapy. Combination of undetectable sMAdCAM-1 with high VTL is also potentially interesting for therapeutic drug monitoring. Baseline RA concentrations are predictive of clinical remission. These findings need to be confirmed in further prospective studies.

Investigation of the Influence of Protein-Losing Enteropathy on Monoclonal Antibody Pharmacokinetics in Mice

Protein losing enteropathy (PLE), which is characterized by substantial loss of plasma proteins into the gastrointestinal (GI) tract, is a complication of a variety of GI diseases, including inflammatory bowel disease. Clinical studies have found that the clearance of monoclonal antibodies (mAb) is often increased in subjects with diseases known to cause PLE; however, direct relationships between PLE and mAb pharmacokinetics have not been demonstrated. This study employed a murine model of colitis to examine the influence of PLE on mAb pharmacokinetics. Mice were given dextran sodium sulfate (DSS, 2% w/v) supplemented tap water as drinking source for 6 days to induce colitis and PLE. Mice were then intravenously injected with 8C2, a murine IgG1 mAb. 8C2 plasma concentrations were measured up to 14 days post injection. Fecal alpha-1-antitrypsin (A1AT) clearance was measured as biomarker for PLE. DSS-treated mice developed PLE of clinically relevant severity. They also showed a transient increase in 8C2 plasma clearance and a decrease in 8C2 plasma exposure. The area under the 8C2 plasma concentration-time curve for the length of the study (AUC_0-14d) reduced from 1368 ± 255 to 594 ± 224 day μg/ml following DSS treatment (p = 0.001). A quantitative relationship between A1AT clearance and 8C2 clearance was obtained via population pharmacokinetic modeling. DSS treatment substantially increased 8C2 clearance and reduced 8C2 exposure. Increased mAb plasma clearance was highly correlated with A1AT fecal clearance, suggesting the possible utility of A1AT fecal clearance as a mechanistic biomarker to predict the pharmacokinetics of therapeutic antibodies.

Immune suppression of IgG response against dairy proteins in major depression

BACKGROUND

Interactions between the digestive system, brain functions and immunoglobulin G (IgG) mediated immunity against food antigens became recently a topic of growing interest in psychiatry research. Psychological stress can activate hypothalamic-pituitary-adrenal axis (HPA) with subsequent hypercortisolemia. It can also influence intestinal permeability and dynamics of IgG response. Major depression can by accompanied either by activation of inflammatory response or by immune suppression (e.g. decreased antibody production) where hypercortisolemia is a significant immune modulator. The aim of our study was to assess IgG immune response against 44 food products in depressed patients and controls along with markers of psychological stress, inflammation, psychometric and dietary parameters.

METHODS

Serum IgG concentrations against 44 food antigens, plasma cortisol, TNF-α, IL-6, IL-1b concentrations were measured and psychometric parameters were evaluated using Hamilton Depression Rating (HAM-D 17), Perceived Stress (PSS-10), and Symptom Checklist (SCL-90) scales in 34 depressed patients and 29 controls. Dietary parameters such as frequency of exposure to food antigens, appetite and weight change were assessed.

RESULTS

There was a significantly lower IgG concentration against dairy in depressed patients compared to controls (post hoc p < 0.05) when there was a high exposure (consumption) to dairy. Our research revealed a significant interaction of IgG concentration against dairy proteins and exposure to dairy between groups (F (2.63) = 3.92, p = 0.025, η² = 0.12). There was no significant difference in mean IgG concentration against food antigens between patients and controls. We found increased concentration of cortisol in depressed patients (t (1.61) = 2.37, p = 0.02) compared to controls. Patients with melancholic depression had significantly higher (M _rank  = 21.27) concentration of cortisol (U = 41, p = 0.006), when compared with the non-melancholic group of patients (M _rank  = 12.16). Cortisol concentration significantly positively correlated with HAM-D 17 (r = 0.442, p = 0.009) and with phobias in SCL-90 scale in patients' group (r = 0.531, p = 0.001). There was decreased concentration of TNF-α (t = 4.256, p < 0.001) in depressed patients compared to controls. IgG concentration of 38.63% food products positively correlated with TNF-α concentration in depressed patients compared to 9.09% of those in healthy controls.

CONCLUSIONS

We observed an immune suppression of IgG response to dairy proteins in depressed patients. Hypercortisolemia with involvement of decreased concentration of TNF-α might play a significant role in suppression of IgG response in depressed patients.

Optineurin deficiency in mice contributes to impaired cytokine secretion and neutrophil recruitment in bacteria-driven colitis

Crohn's disease (CD) is associated with delayed neutrophil recruitment and bacterial clearance at sites of acute inflammation as a result of impaired secretion of proinflammatory cytokines by macrophages. To investigate the impaired cytokine secretion and confirm our previous findings, we performed transcriptomic analysis in macrophages and identified a subgroup of individuals with CD who had low expression of the autophagy receptor optineurin (OPTN). We then clarified the role of OPTN deficiency in: macrophage cytokine secretion; mouse models of bacteria-driven colitis and peritonitis; and zebrafish Salmonella infection. OPTN-deficient bone-marrow-derived macrophages (BMDMs) stimulated with heat-killed Escherichia coli secreted less proinflammatory TNFα and IL6 cytokines despite similar gene transcription, which normalised with lysosomal and autophagy inhibitors, suggesting that TNFα is mis-trafficked to lysosomes via bafilomycin-A-dependent pathways in the absence of OPTN. OPTN-deficient mice were more susceptible to Citrobacter colitis and E. coli peritonitis, and showed reduced levels of proinflammatory TNFα in serum, diminished neutrophil recruitment to sites of acute inflammation and greater mortality, compared with wild-type mice. Optn-knockdown zebrafish infected with Salmonella also had higher mortality. OPTN plays a role in acute inflammation and neutrophil recruitment, potentially via defective macrophage proinflammatory cytokine secretion, which suggests that diminished OPTN expression in humans might increase the risk of developing CD.

Growth hormone secretagogue receptor is important in the development of experimental colitis

BACKGROUND

Growth hormone secretagogue receptor (GHSR) and its ligand, ghrelin, are important modulators in weight control and energy homeostasis. Recently, ghrelin is also involved in experimental colitis, but the role of GHSR in the development of colitis is unclear. The aim was to examine the underlying mechanism of GHSR in IBD development.

METHODS

The temporal expression of GHSR/ghrelin was determined in dextran sulphate sodium (DSS) induced colitis in Wt mice. The severity of DSS induced colitis from GHSR(-/-) and WT mice was compared at clinical/pathological levels. Furthermore, the function of macrophages was evaluated in vivo and in vitro.

RESULTS

Lack of GHSR attenuated colitis significantly at the clinical and pathological levels with reduced colonic pro-inflammatory cytokines (P < 0.05). This is consistent with the observation of less colonic macrophage infiltration and TLRs expression from DSS-treated GHSR(-/-) mice compared to WT mice (P < 0.05). Furthermore, there was significantly reduced pro-inflammatory cytokines in LPS-stimulated macrophages in vitro from GHSR(-/-) mice than WT mice (P < 0.05). Moreover, D-lys(3)-GHRP6 (a GHSR antagonist) reduced LPS-induced macrophage pro-inflammatory cytokines from WT mice in vitro.

CONCLUSIONS

GHSR contributes to development of acute DSS-induced colitis, likely via elevated pro-inflammatory cytokines and activation of macrophages. These data suggest GHSR as a potential therapeutic target for IBD.

Bioluminescence imaging for IL-1β expression in experimental colitis

Background

Interleukin 1 beta (IL-1β) contributes to the development of inflammatory bowel disease (IBD) and is correlated with the severity of intestinal inflammation. However, the precise source of IL-1β producing cells in DSS colitis is currently not known.

Methods

To determine IL-1β activity during intestinal inflammation in real time, an IL-1β transgenic mouse has been generated by incorporating the firefly luciferase gene driven by a 4.5-kb fragment of human IL-1β gene promoter (named cHS4I-hIL-1βP-Luc transgenic mice). Dextran sodium sulfate (DSS) induced colitis was confirmed with clinical presentation and histopathology.

Results

A substantial increase in luciferase activity (reflecting IL-1β production) in the region of inflamed colon was observed in a time dependent manner, followed by additional activity in the region of the mesenteric lymph node. The up-regulated luciferase activity was suppressed by dexamethasone (steroids) during DSS challenge, consistent with reduced severity of colitis, confirming the specificity of luciferase activity.

Conclusions

Our data suggests that bioluminescence is an interesting technology, which may be used to evaluate transcription of various genes in real time in experimental colitis.

Red wine polyphenolics reduce the expression of inflammation markers in human colon-derived CCD-18Co myofibroblast cells: potential role of microRNA-126

Chronic intestinal inflammation is an established risk factor for colon cancer. Polyphenolic compounds from fruit and vegetables have been shown to have anti-inflammatory properties in several cell lines and tissues. However, their anti-inflammatory mechanisms, involving microRNAs in the regulation of inflammation, have not been extensively investigated. The goal of this research was to assess the chemopreventive potential of polyphenolics extracted from red wine made with Lenoir grapes (Vitis aestivalis hybrid) in human colon-derived CCD-18Co myofibroblasts cells, and to assess the potential involvement of microRNA-126 (miR-126) in the underlying mechanisms. The results show that the polyphenolic red wine extract (WE) decreased mRNA expression of lipopolysaccharide (LPS)-induced inflammatory mediators NF-kB, ICAM-1, VCAM-1, and PECAM-1 by 1.95-, 1.98-, 1.52-, and 1.84-fold respectively, in a dose dependent manner (0-100 μg of gallic acid equivalent (GAE) mL(-1)) down to 0.80-, 0.79-, 0.66-, and 0.68-fold in DMSO-treated control cells not challenged with LPS, respectively. Correspondingly, miR-126, which has a target region within the 3'-UTR of VCAM-1 mRNA, was increased 2.79-fold by the WE at 100 μg GAE mL(-1). The potential role of miR-126 was confirmed by transfecting cells with a specific miR-126-antagomir, as-miR-126. Transfection with as-miR-126 down-regulated miR-126 to 0.71-fold in the control cells and up-regulated mRNA levels of NF-kB, ICAM-1, VCAM-1, and PECAM-1 to 1.80-, 1.49-, 2.30-, and 1.95-fold of controls, respectively. WE at 100 μg GAE mL(-1) partially reversed the effects of the as-miR-126 to 1.02-, 1.01-, 1.04-, and 1.05-fold, for mRNA levels of NF-kB, ICAM-1, VCAM-1, and PECAM-1 respectively. This indicates the potential role of miR-126 in the anti-inflammatory properties of polyphenolics from red wine in CCD-18Co myofibroblasts cells.

Tumor necrosis factor-α and Muc2 mucin play major roles in disease onset and progression in dextran sodium sulphate-induced colitis

The sequential events and the inflammatory mediators that characterize disease onset and progression of ulcerative colitis (UC) are not well known. In this study, we evaluated the early pathologic events in the pathogenesis of colonic ulcers in rats treated with dextran sodium sulfate (DSS). Following a lag phase, day 5 of DSS treatment was found clinically most critical as disease activity index (DAI) exhibited an exponential rise with severe weight loss and rectal bleeding. Surprisingly, on days 1-2, colonic TNF-α expression (70-80-fold) and tissue protein (50-fold) were increased, whereas IL-1β only increased on days 7-9 (60-90-fold). Days 3-6 of DSS treatment were characterized by a prominent down regulation in the expression of regulatory cytokines (40-fold for IL-10 and TGFβ) and mucin genes (15-18 fold for Muc2 and Muc3) concomitant with depletion of goblet cell and adherent mucin. Remarkably, treatment with TNF-α neutralizing antibody markedly altered DSS injury with reduced DAI, restoration of the adherent and goblet cell mucin and IL-1β and mucin gene expression. We conclude that early onset colitis is dependent on TNF-α that preceded depletion of adherent and goblet cell mucin prior to epithelial cell damage and these biomarkers can be used as therapeutic targets for UC.

The atypical cannabinoid O-1602 protects against experimental colitis and inhibits neutrophil recruitment

BACKGROUND

Cannabinoids are known to reduce intestinal inflammation. Atypical cannabinoids produce pharmacological effects via unidentified targets. We were interested in whether the atypical cannabinoid O-1602, reportedly an agonist of the putative cannabinoid receptor GPR55, reduces disease severity of dextran sulfate sodium (DSS) and trinitrobenzene sulfonic acid (TNBS)-induced colitis in C57BL/6N and CD1 mice.

METHODS

DSS (2.5% and 4%) was supplied in drinking water for 1 week while TNBS (4 mg) was applied as a single intrarectal bolus.

RESULTS

Both treatments caused severe colitis. Injection of O-1602 (5 mg/kg intraperitoneally) significantly reduced macroscopic and histological colitis scores, and myeloperoxidase activity. The protective effect was still present in cannabinoid receptor 1 (CB₁) and 2 (CB₂) double knockout mice and mice lacking the GPR55 gene. To investigate a potential mechanism underlying the protection by O-1602 we performed neutrophil chemotactic assays. O-1602 concentration-dependently inhibited migration of murine neutrophils to keratinocyte-derived chemokine (KC), N-formyl-methionyl-leucyl-phenylalanine (fMLP), and the N-formyl-peptide receptor ligand WKYMVm. The inhibitory effect of O-1602 was preserved in neutrophils from CB₁/CB₂ double knockout and GPR55 knockout mice. No differences were seen in locomotor activity between O-1602-treated and control mice, indicating lack of central sedation by this compound.

CONCLUSIONS

Our data demonstrate that O-1602 is protective against experimentally induced colitis and inhibits neutrophil recruitment independently of CB₁, CB₂, and GPR55 receptors. Thus, atypical cannabinoids represent a novel class of therapeutics that may be useful for the treatment of inflammatory bowel diseases.

Gp91(phox) contributes to the development of experimental inflammatory bowel disease

Inflammatory bowel disease (IBD) is related to dysfunction of intestinal immunity. Neutrophils have an important role in innate immunity via the oxidative burst, using the p47phox- and gp91(phox)-containing NAD(P)H oxidase known as Nox2. In dextran sulphate sodium (DSS)-induced colitis, no significant difference in inflammation between p47(phox-/-) and wild-type (WT) mice was reported, but there was improved endothelium-dependent arteriolar dilation in gp91(phox-/-) mice, compared with that in WT mice. Gp91(phox) and p47 (phox) are not only essential components of phagocyte Nox2, but also have roles in other enzymes. Thus the differences in response of their respective gene knockout mice to DSS challenge are not completely unexpected, but need further investigation. The clinicopathological changes and immunological responses to DSS challenge have not been fully described in gp91(phox-/-) mice. Thus we treated WT and gp91(phox-/-) mice with 2.5% DSS for 7 days. The gp91(phox-/-) mice developed less severe colitis than WT mice following DSS treatment, reflected by a smaller body weight loss, less rectal bleeding and fewer histopathological changes. Less colonic myeloperoxidase was observed in gp91(phox-/-), compared with WT mice, following DSS challenge, correlating with interleukin (IL)-6 production. IL-10 was upregulated in both gp91(phox-/-) and WT mice, but was significantly higher in the latter, following 7 days DSS challenge. These results suggest that gp91(phox-/-) mice are less susceptible to acute DSS-induced colitis, possibly because of a reduced oxidative burst in the intestine and, consequently, less tissue damage.

CC chemokine ligand 3 overcomes the bacteriocidal and phagocytic defect of macrophages and hastens recovery from experimental otitis media in TNF-/- mice

Innate immune mechanisms are crucial in defense against bacterial illnesses in humans, as evidenced by abnormal antibacterial responses due to defects in TLR signaling, seen in children with MyD88 or IL-1R-associated kinase 4 deficiency. Otitis media (OM) is the most common disease of childhood, and the role of innate immune molecules in this disorder remains unclear. In a murine model of OM, we show that, in the absence of TNF, a key effector of innate immunity, this disease is prolonged after middle ear infection with nontypeable Haemophilus influenzae (NTHi). In the absence of TNF, mice fail to upregulate both TLRs and downstream genes and proteins, such as CCL3, resulting in defects in both inflammatory cell recruitment and macrophage function. Peritoneal macrophages of mice lacking TNF have a diminished ability to phagocytose and kill NTHi, and this defect is partially corrected in vitro by exogenous rTNF. Addition of rCCL3 alone or in combination with rTNF restores phagocytosis and killing by TNF-deficient macrophages to that of unstimulated wild-type macrophages. In vivo administration of rCCL3 to animals deficient in TNF fully restores the ability to control OM due to NTHi, whereas a CCL3-blocking Ab impaired the ability of wild-type mice to recover from OM. Thus, CCL3 is a potent downstream effector of TNF-mediated inflammation in vitro and in vivo. Manipulation of CCL3 and/or TNF may prove to be effective therapeutic approaches in OM or other conditions associated with defective TNF generation.

Interleukin-6 is essential for zwitterionic polysaccharide-mediated abscess formation

Abscess formation associated with secondary peritonitis causes severe morbidity and can be fatal. Formation of abscesses requires the presence of CD4+ T-cells. Zwitterionic polysaccharides (ZPSs) represent a novel class of immunomodulatory bacterial antigens that stimulate CD4+ T-cells in a major histocompatibility complex (MHC) class II-dependent manner. The capsular polysaccharide Sp1 of Streptococcus pneumoniae serotype 1 possesses a zwitterionic charge with free amino groups and promotes T-cell-dependent abscess formation in an experimental mouse model. So far, nothing is known about the function of Interleukin (IL)-6 in intraperitoneal abscess formation. Here, we demonstrate that macrophages and dendritic cells (DCs), the most prevalent professional antigen-presenting cells involved in the formation of abscesses, secrete Interleukin (IL)-6 and are incorporated in the abscess capsule. Sp1 inhibits apoptosis of CD4 + T-cells and causes IL-17 expression by CD4+ T-cells in an IL-6-dependent manner. Abrogation of the Sp1-induced pleiotropic effects of IL-6 in IL-6-deficient mice and mice treated with an IL-6-specific neutralizing antibody results in significant inhibition of abscess formation. The data delineate the essential role of IL-6 in the linkage of innate and adaptive immunity in polysaccharide-mediated abscess formation.

Granulocyte-macrophage colony-stimulating factor enhances wound healing in diabetes via upregulation of proinflammatory cytokines

BACKGROUND

Chronic ulceration, especially in diabetes, remains a substantial clinical problem. Exogenous granulocyte-macrophage colony-stimulating factor (GM-CSF) is efficacious in the treatment of chronic wound healing in both animal models and patients, but its role in diabetic wounds remains to be explored. Objectives Using a diabetic mouse model, to investigate the role of GM-CSF in wound healing.

METHODS

Clinical observation, histopathology, immunohistochemistry and cytokine assays.

RESULTS

There was a significant reduction (50%) in GM-CSF production in the wounds of the diabetics compared with nondiabetics. Exogenous GM-CSF substantially enhanced the wound healing in diabetic mice, accompanied by increased interleukin-6 and monocyte chemoattractant protein-1 production. The elevated cytokines correlated with increased neovascularization, and infiltration of macrophages and neutrophils. GM-CSF showed no beneficial effects in nondiabetic wound healing.

CONCLUSIONS

Our results provide useful guidelines for the clinical management of chronic ulceration in diabetes.

Role of TNF receptors, TNFR1 and TNFR2, in dextran sodium sulfate-induced colitis

BACKGROUND

In this study we determined the consequence of the absence of each TNF receptor, TNFR1 or TNFR2, in the dextran sulfate sodium (DSS) model of colitis.

METHODS

Wildtype (WT), TNFR1(-/-) and TNFR2(-/-) mice were fed 3% w/v DSS in drinking water for 5 days followed by 2 (day 7) or 7 (day 12) days of tap water.

RESULTS

The colons from untreated TNFR1(-/-) and TNFR2(-/-) mice were histologically normal. Following DSS, all strains became inflamed. TNFR1(-/-) mice had a more severe clinical score at days 8 and 9 compared to WT and TNFR2(-/-) mice despite similar histopathological damage in their colons. The more severe clinical score was associated with a reduced macrophage infiltration into the colonic mucosa. TNFR2(-/-) mice showed increased indicators of disease including increased colon weight, a shrunken cecum, and an increased number of ulcers compared to TNFR1(-/-) and WT strains at day 7. Mucosal levels of TNFR2 were elevated in colitic mice compared to uninflamed controls, with no difference between strains on day 7 but on day 12, unlike WT mice, levels were reduced in TNFR1(-/-) mice. There was no difference in the number of TUNEL-positive apoptotic colonic epithelial cells between strains, nor in total cleaved caspase 3 levels between strains, measured by Western blot of colon homogenates.

CONCLUSIONS

While deficiency of either receptor contributes to some measures of DSS colitis, the histopathological scores are similar, indicating that TNF receptors either do not play a major role or are redundant in the pathology associated with DSS colitis.

The role of granulocyte macrophage-colony-stimulating factor in acute intestinal inflammation

An imbalance of mucosal pro- and anti-inflammatory cytokines is crucial in the pathogenesis of inflammatory bowel disease (IBD). GM-CSF influences the development of hemopoietic cells. The precise role of GM-CSF in IBD remains to be elucidated. GM-CSF gene knockout (GM-CSF(-/-)) and wild-type (Wt) mice were challenged with 2.5% dextran sulfate sodium (DSS) for 7 days. The ensued clinical and pathological changes, macrophage infiltration, colonic cytokine production, and bacterial counts were examined. DSS-treated GM-CSF(-/-) mice developed more severe acute colitis than DSS-treated Wt mice, reflected by a greater body weight loss, more rectal bleeding, and aggravated histopathological changes. More infiltrating macrophages were observed in GM-CSF(-/-), compared with Wt mice following DSS challenge, correlating with monocyte chemoattractant protein-1 (MCP-1) production. The levels of colonic IL-17 and TNF-alpha were increased significantly in GM-CSF(-/-) mice, but not in Wt mice, following DSS administration. The level of IL-6 was increased by 1.5- and 2-fold in the colon of GM-CSF(-/-) and Wt mice, respectively, following DSS challenge. No significant changes in IL-4 and IFN-gamma were detected in Wt and GM-CSF(-/-) mice following DSS treatment. The bacteria recovery from colon was increased about 15- and 5-fold, respectively, in Wt mice and GM-CSF(-/-) mice following DSS challenge. These results suggest that GM-CSF(-/-) mice are more susceptible to acute DSS-induced colitis, possibly because of an impaired gut innate immune response as a result of diminished GM-CSF.

The effect of restraint stress on experimental colitis is IFN-gamma independent

Stress, a protective reaction to external threats, may be deleterious if linked to an inflammatory stimulus. Stress may influence intestinal immunity, thereby contributing to the development of colitis. Less severe histological abnormalities and clinical scores were detected in dextran sulphate sodium (DSS)-induced colitis in IFN-gamma(-/-), compared to Wt, mice. Disease severity was increased by restraint stress in DSS-treated IFN-gamma(-/-) and Wt mice, accompanied by suppressed colonic pro and anti inflammatory cytokine responses. Our data suggest that IFN-gamma is important in the development of acute colitis. Stress increases the severity of colitis, but is independent of the IFN-gamma pathway.

A role for tumor necrosis factor-alpha in experimental Bacillus cereus endophthalmitis pathogenesis

PURPOSE

To determine the contribution of tumor necrosis factor-alpha (TNFalpha) in the pathogenesis of experimental Bacillus cereus endophthalmitis.

METHODS

Experimental B. cereus endophthalmitis was induced in wild-type control (B6.129F1) and age-matched homozygous TNFalpha knockout mice (TNFalpha(-/-), B6.129S6-Tnf(tm1Gk1)/J). At various times after infection, eyes were analyzed by electroretinography and were harvested for quantitation of bacteria, myeloperoxidase, proinflammatory cytokines and chemokines, and histologic analysis.

RESULTS

B. cereus replicated more rapidly in the eyes of TNFalpha(-/-) mice than in the eyes of B6.129F1 mice. Retinal function decreased more rapidly in TNFalpha(-/-) mice than in B6.129F1 mice. Retinal layers were not as structurally intact at 6 and 12 hours after infection in TNFalpha(-/-) eyes as in B6.129F1 eyes. Histologic analysis suggested less polymorphonuclear leukocyte (PMN) infiltration into the vitreous of TNFalpha(-/-) mice than of B6.129F1 mice. B6.129F1 eyes also had greater myeloperoxidase concentrations than did eyes of TNFalpha(-/-) mice. In general, concentrations of proinflammatory cytokines and chemokines (IL-1beta, KC, IL-6, and MIP-1alpha) were greater in eyes of TNFalpha(-/-) mice than of B6.129F1 mice.

CONCLUSIONS

TNFalpha is important to intraocular pathogen containment by PMNs during experimental B. cereus endophthalmitis. In the absence of TNFalpha, fewer PMNs migrated into the eye, facilitating faster bacterial replication and retinal function loss. Although greater concentrations of proinflammatory cytokines were synthesized in the absence of TNFalpha, the resultant inflammation was diminished, and an equally devastating course of infection occurred.