Selective gelatinase blockage ameliorates acute DSS colitis

Neutrophils in Inflammatory Diseases: Unraveling the Impact of Their Derived Molecules and Heterogeneity

Inflammatory diseases involve numerous disorders and medical conditions defined by an insufficient level of self-tolerance. These diseases evolve over the course of a multi-step process through which environmental variables play a crucial role in the emergence of aberrant innate and adaptive immunological responses. According to experimental data accumulated over the past decade, neutrophils play a significant role as effector cells in innate immunity. However, neutrophils are also involved in the progression of numerous diseases through participation in the onset and maintenance of immune-mediated dysregulation by releasing neutrophil-derived molecules and forming neutrophil extracellular traps, ultimately causing destruction of tissues. Additionally, neutrophils have a wide variety of functional heterogeneity with adverse effects on inflammatory diseases. However, the complicated role of neutrophil biology and its heterogeneity in inflammatory diseases remains unclear. Moreover, neutrophils are considered an intriguing target of interventional therapies due to their multifaceted role in a number of diseases. Several approaches have been developed to therapeutically target neutrophils, involving strategies to improve neutrophil function, with various compounds and inhibitors currently undergoing clinical trials, although challenges and contradictions in the field persist. This review outlines the current literature on roles of neutrophils, neutrophil-derived molecules, and neutrophil heterogeneity in the pathogenesis of autoimmune and inflammatory diseases with potential future therapeutic strategies.

Effect of electroacupuncture on the degradation of collagen in pelvic floor supporting tissue of stress urinary incontinence rats

INTRODUCTION AND HYPOTHESIS

To examine the changes induced by electroacupuncture in stress urinary incontinence (SUI) rats, including the urodynamics and collagen degradation-related cytokine molecular biological expression changes, and to explore the effect and mechanism of EA treatment in SUI.

METHODS

Female SPF Sprague-Dawley rats were randomly assigned to five groups (n = 10): sham, model, electroacupuncture control, electroacupuncture, and blocker. The leak point pressure (LPP) and maximum bladder capacity (MBC) were measured for each group of rats, and collagen I, collagen III, matrix metalloproteinases (MMPs), and tissue inhibitor of metalloproteinase (TIMPs) in the anterior vaginal wall of rats in each group were determined by reverse transcription-polymerase chain reaction and western blotting. The data were analyzed by one-way analysis of variance or Kruskal-Wallis test.

RESULTS

Electroacupuncture Shenshu (BL23) and Huiyang (BL35) increased the LPP and MBC in SUI rats (P < 0.05). Electroacupuncture treatment significantly increased the protein expression of collagen I and collagen III in the anterior vaginal wall of SUI rats (P < 0.05) and significantly reduced the protein expression of MMP1, MMP2, and MMP9 (P < 0.05).

CONCLUSIONS

Electroacupuncture stimulation can alleviate the signs of SUI, and its mechanism is related to the degradation of collagen in the anterior vaginal wall.

Effect of electroacupuncture on the intestinal microflora in rats with stress urinary incontinence

OBJECTIVE

To examine the effect of electroacupuncture on the urodynamics and gut microbiota of rats with stress urinary incontinence (SUI).

MATERIALS AND METHODS

Thirty 2-month-old female Sprague-Dawley (SD) rats were randomly assigned to 4 groups: normal (N), model (M), nonacupoint electric acupuncture control (NAAC), and electroacupuncture (EA). An SUI rat model was established through vaginal balloon dilatation and bilateral oophorectomy. After various treatments, urodynamic tests were performed, and feces were collected. 16S rRNA sequencing analysis was used to investigate SUI-related changes in the intestinal flora.

RESULTS

After treatment, compared with those of the M group, the leak point pressure and maximum bladder capacity of the electroacupuncture groups increased (P<0.05). The species community compositions of the N and M groups differed at the genus level, and there were 15 differentially abundant bacterial genera (P<0.05). The Blautia proportion was increased by electroacupuncture treatment (P<0.05) and was significantly positively correlated with the electroacupuncture treatment of SUI (according to Spearman correlation analysis).

CONCLUSION

Electroacupuncture treatment can improve signs of urine leakage in rats with SUI rats by increasing the leak point pressure and maximum bladder capacity. The enrichment of Blautia by electroacupuncture treatment enrichment may be related to SUI sign improvement.

Digestive Inflammation: Role of Proteolytic Dysregulation

Dysregulation of the proteolytic balance is often associated with diseases. Serine proteases and matrix metalloproteases are involved in a multitude of biological processes and notably in the inflammatory response. Within the framework of digestive inflammation, several studies have stressed the role of serine proteases and matrix metalloproteases (MMPs) as key actors in its pathogenesis and pointed to the unbalance between these proteases and their respective inhibitors. Substantial efforts have been made in developing new inhibitors, some of which have reached clinical trial phases, notwithstanding that unwanted side effects remain a major issue. However, studies on the proteolytic imbalance and inhibitors conception are directed toward host serine/MMPs proteases revealing a hitherto overlooked factor, the potential contribution of their bacterial counterpart. In this review, we highlight the role of proteolytic imbalance in human digestive inflammation focusing on serine proteases and MMPs and their respective inhibitors considering both host and bacterial origin.

Morphological elucidation of short-chain fatty acid receptor GPR41-positive enteric sensory neurons in the colon of mice with dextran sulfate sodium-induced colitis

Although the etiology of inflammatory bowel disease (IBD) remains unclear, it has generally been accepted that abnormalities in the intestinal immune system and dysbiosis of the gut microbiota are involved in the pathology of IBD. Recently, short-chain fatty acids (SCFAs) produced by gut microbiota were reported to maintain intestinal homeostasis through their receptors, such as GPR41. However, there are contradictory reports about the role of GPR41 in intestinal inflammation. Consequently, the roles of GPR41 in dysbiosis induced by intestinal inflammation remain unclear. Thus, we investigated the distribution of GPR41 in the colonic mucosa of mice with dextran sulfate sodium (DSS)-induced colitis. GPR41-immunoreactive fibrous structures were observed in the colonic lamina propria and muscularis layer of normal mice. In addition, GPR41-immunoreactive fibrous structures partly colocalized with calcitonin gene-related peptide (CGRP; a neurotransmitter of cholinergic enteric sensory neurons)-immunoreactive nerve fibers in the colonic lamina propria, indicating that GPR41 is expressed in cholinergic intrinsic sensory neurons. Furthermore, both GPR41-immunoreactivities and CGRP-immunoreactivities were significantly increased in the lamina propria of the colon in mice with DSS-induced colitis. Interestingly, GPR41-immunoreactivities were often found in close proximity to F4/80⁺ macrophages in the colonic mucosa of normal mice, and their frequency was elevated in the colonic mucosa of mice with DSS-induced colitis. Therefore, the crosstalk between SCFA-sensing intrinsic sensory neurons and macrophages might be involved in the pathology of acute colitis.

Tenascin-C Is Increased in Inflammatory Bowel Disease and Is Associated with response to Infliximab Therapy

Tenascin-C (TNC) is an extracellular matrix glycoprotein expressed in response to inflammation and tissue damage. The role of TNC in patients with inflammatory bowel disease (IBD) is not well understood. In this study, we analyzed the expression of TNC in the inflamed mucosa of patients with ulcerative colitis (UC) and Crohn's disease (CD). Serum TNC levels were determined by the enzyme-linked immunosorbent assay (ELISA), and the levels of TNC in patients with different disease activities were compared. The expression of TNC was derived from a GEO dataset. THP-1 cells were stimulated with TNC to evaluate the proinflammatory role of TNC. We found higher TNC expression in the inflamed mucosa of patients with UC and CD compared with normal controls (NCs). TNC was mainly expressed in the stromal area of the intestinal mucosa. The median serum levels of TNC were significantly higher in UC (median 74.1 ng/ml, range 42.6–102.1 ng/ml) and CD (median 59.2 ng/ml, range 44.0–80.9 ng/ml). We also found that serum TNC levels were correlated with Mayo scores in UC and Crohn's disease activity index (CDAI) in CD. Through GSE14580, we demonstrated that patients who were nonresponsive to infliximab treatment had higher mucosal TNC mRNA expression. High TNC mRNA expression in the inflamed intestinal mucosa was associated with poor response to infliximab therapy in patients with UC. Furthermore, THP-1 cells stimulated with TNC showed increased expression of IL-6, but not TNF-α, IL-8, MCP-1, or IL-1β. Thus, increased TNC levels may participate in the pathogenesis of IBD and may serve as a biomarker for disease activity and response to treatment with infliximab.

Pituitary Adenylate Cyclase-Activating Polypeptide-A Neuropeptide as Novel Treatment Option for Subacute Ileitis in Mice Harboring a Human Gut Microbiota

The neuropeptide Pituitary adenylate cyclase-activating polypeptide (PACAP) is well-known for its important functions in immunity and inflammation. Data regarding anti-inflammatory properties of PACAP in the intestinal tract are limited, however. In our present preclinical intervention study we addressed whether PACAP treatment could alleviate experimental subacute ileitis mimicking human gut microbiota conditions. Therefore, secondary abioitic mice were subjected to human fecal microbiota transplantation (FMT) and perorally infected with low-dose Toxoplasma gondii to induce subacute ileitis on day 0. From day 3 until day 8 post-infection, mice were either treated with synthetic PACAP38 or placebo. At day 9 post-infection, placebo, but not PACAP treated mice exhibited overt macroscopic sequelae of intestinal immunopathology. PACAP treatment further resulted in less distinct apoptotic responses in ileal and colonic epithelia that were accompanied by lower T cell numbers in the mucosa and lamina propria and less secretion of pro-inflammatory cytokines in intestinal ex vivo biopsies. Notably, ileitis-associated gut microbiota shifts were less distinct in PACAP as compared to placebo treated mice. Inflammation-ameliorating effects of PACAP were not restricted to the intestines, but could also be observed in extra-intestinal including systemic compartments as indicated by lower apoptotic cell counts and less pro-inflammatory cytokine secretion in liver and lungs taken from PACAP treated as compared to placebo control mice, which also held true for markedly lower serum TNF and IL-6 concentrations in the former as compared to the latter. Our preclinical intervention study provides strong evidence that synthetic PACAP alleviates subacute ileitis and extra-intestinal including systemic sequelae of T cell-driven immunopathology. These findings further support PACAP as a novel treatment option for intestinal inflammation including inflammatory bowel diseases (IBD).

Permeability analyses and three dimensional imaging of interferon gamma-induced barrier disintegration in intestinal organoids

The aberrant regulation of the epithelial barrier integrity is involved in many diseases of the digestive tract, including inflammatory bowel diseases and colorectal cancer. Intestinal epithelial cell organoid cultures provide new perspectives for analyses of the intestinal barrier in vitro. However, established methods of barrier function analyses from two dimensional cultures have to be adjusted to the analysis of three dimensional organoid structures. Here we describe the methodology for analysis of epithelial barrier function and molecular regulation in intestinal organoids. Barrier responses to interferon-γ of intestinal organoids with and without epithelial cell-specific deletion of the interferon-γ-receptor 2 gene were used as a model system. The established method allowed monitoring of the kinetics of interferon-γ-induced permeability changes in living organoids. Proteolytic degradation and altered localization of the tight junction proteins claudin-2, -7, and - 15 was detected using confocal spinning disc microscopy with 3D reconstruction. Hessian analysis was used for quantification of re-localization of claudins. In summary, we provide a novel methodologic approach for quantitative analyses of intestinal epithelial barrier functions in the 3D organoid model.

Comparisons of gut microbiota profiles in wild-type and gelatinase B/matrix metalloproteinase-9-deficient mice in acute DSS-induced colitis

Gut microbiota help to educate the immune system and a number of involved immune cells were recently characterized. However, specific molecular determinants in these processes are not known, and, reciprocally, little information exists about single host determinants that alter the microbiota. Gelatinase B/matrix metalloproteinase-9 (MMP-9), an innate immune regulator and effector, has been suggested as such a host determinant. In this study, acute colitis was induced in co-housed MMP-9^-/- mice (n = 10) and their wild-type (WT) littermates (n = 10) via oral administration of 3% dextran sodium sulfate (DSS) for 7 days followed by 2 days of regular drinking water. Control mice (10 WT and 10 MMP-9^-/-) received normal drinking water. Fecal samples were collected at time of sacrifice and immediately frozen at −80 °C. Microbiota analysis was performed using 16S rRNA amplicon sequencing on Illumina MiSeq and taxonomic annotation was performed using the Ribosomal Database Project as reference. Statistical analysis correcting for multiple testing was done using R. No significant differences in clinical or histopathological parameters were found between both genotypes with DSS-induced colitis. Observed microbial richness at genus level and microbiota composition were not significantly influenced by host genotype. In contrast, weight loss, disease activity index, cage, and phenotype did significantly influence the intestinal microbiota composition. After multivariate analysis, cage and phenotype were identified as the sole drivers of microbiota composition variability. In conclusion, changes in fecal microbiota composition were not significantly altered in MMP-9-deficient mice compared to wild-type littermates, but instead were mainly driven by DSS-induced colonic inflammation.

A protein that regulates aspects of the immune system has been proposed to influence gut microbial populations implicated in the inflammatory conditions known as colitis, but new evidence suggests the protein has no such effect. Ghislain Opdenakker and colleagues at the Rega Institute for Medical Research in Belgium examined the issue in mice with chemically induced colitis. The gut microbes of normal “wild-type” animals were compared with those in animals lacking the gene for the protein, “gelatinase B/matrix metalloproteinase-9”. The absence of the gene, and therefore of the protein it codes for, caused no significant alteration in the gut microbial population. The presence of colitis, however, did alter the gut microbial population relative to mice with no colitis. The results will assist work to understand the networks of cause and effect linking gut microbes and colitis.

The Dual Role of Neutrophils in Inflammatory Bowel Diseases

Inflammatory bowel diseases (IBD), including Crohn’s disease and ulcerative colitis, are characterised by aberrant immunological responses leading to chronic inflammation without tissue regeneration. These two diseases are considered distinct entities, and there is some evidence that neutrophil behaviour, above all other aspects of immunity, clearly separate them. Neutrophils are the first immune cells recruited to the site of inflammation, and their action is crucial to limit invasion by microorganisms. Furthermore, they play an essential role in proper resolution of inflammation. When these processes are not tightly regulated, they can trigger positive feedback amplification loops that promote neutrophil activation, leading to significant tissue damage and evolution toward chronic disease. Defective chemotaxis, as observed in Crohn’s disease, can also contribute to the disease through impaired microbe elimination. In addition, through NET production, neutrophils may be involved in thrombo-embolic events frequently observed in IBD patients. While the role of neutrophils has been studied in different animal models of IBD for many years, their contribution to the pathogenesis of IBD remains poorly understood, and no molecules targeting neutrophils are used and validated for the treatment of these pathologies. Therefore, it is crucial to improve our understanding of their mode of action in these particular conditions in order to provide new therapeutic avenues for IBD.

The Role of Gelatinases in Campylobacter Jejuni Infection of Gnotobiotic Mice

Matrix metalloproteinases (MMP)-2 and -9 (also referred to gelatinases-A and -B, respectively) are upregulated in the inflamed gut of mice and men. We recently demonstrated that synthetic gelatinase blockage reduced large intestinal pro-inflammatory immune responses and apoptosis following murine Campylobacter (C.) jejuni infection. In order to address which gelatinase mediates C. jejuni-induced immune responses, gnotobiotic MMP-2(-/-), MMP-9(-/-), and wildtype (WT) mice were generated by broadspectrum antibiotic treatment and perorally infected with C. jejuni strain 81-176. The pathogen stably colonized the murine intestinal tract irrespective of the genotype but did not translocate to extra-intestinal compartments. At days 8 and 14 postinfection (p.i.), less pronounced colonic histopathological changes were observed in infected MMP-2(-/-) mice, less distinct epithelial apoptosis, but more epithelial proliferation in both MMP-2(-/-) and MMP-9(-/-) mice, as compared to WT controls. Reduced immune responses in gelatinase-deficient mice were characterized by lower numbers of effector as well as innate and adaptive immune cells within the colonic mucosa and lamina propria. The expression of IL-22, IL-18, IL-17A, and IL-1β mRNA was higher in the colon of MMP-2(-/-) as compared to WT mice. In conclusion, both MMP-2 and MMP-9 are differentially involved in mediating C. jejuni-induced intestinal immunopathology.

A new therapeutic association to manage relapsing experimental colitis: Doxycycline plus Saccharomyces boulardii

Immunomodulatory antibiotics have been proposed for the treatment of multifactorial conditions such as inflammatory bowel disease. Probiotics are able to attenuate intestinal inflammation, being considered as safe when chronically administered. The aim of the study was to evaluate the anti-inflammatory effects of doxycycline, a tetracycline with immunomodulatory properties, alone and in association with the probiotic Saccharomyces boulardii CNCMI-745. Doxycycline was assayed both in vitro (Caco-2 epithelial cells and RAW 264.7 macrophages) and in vivo, in the trinitrobenzenesulfonic acid (TNBS) model of rat colitis and the dextran sodium sulfate (DSS) model of mouse colitis. In addition, the anti-inflammatory effect of the association of doxycycline and the probiotic was evaluated in vitro and in vivo in a DSS model of reactivated colitis in mice. Doxycycline displayed immunomodulatory activity in vitro, reducing IL-8 production by intestinal epithelial cells and nitric oxide by macrophages. Doxycycline administration to TNBS-colitic rats (5, 10 and 25 mg/kg) ameliorated the intestinal inflammatory process, being its efficacy comparable to that previously showed by minocycline. Doxycycline treatment was also effective in reducing acute intestinal inflammation in the DSS model of mouse colitis. The association of doxycycline and S. boulardii helped managing colitis in a reactivated model of colitis, by reducing intestinal inflammation and accelerating the recovery and attenuating the relapse. This was evidenced by a reduced disease activity index, colonic tissue damage and expression of inflammatory mediators. This study confirms the intestinal anti-inflammatory activity of doxycycline and supports the potential use of its therapeutic association with S. boulardii for the treatment of inflammatory bowel diseases, in which doxycycline is used to induce remission and long term probiotic administration helps to prevent the relapses.

Matrix metalloproteinases in inflammatory bowel disease: an update

Matrix metalloproteinases (MMPs) are known to be upregulated in inflammatory bowel disease (IBD) and other inflammatory conditions, but while their involvement is clear, their role in many settings has yet to be determined. Studies of the involvement of MMPs in IBD since 2006 have revealed an array of immune and stromal cells which release the proteases in response to inflammatory cytokines and growth factors. Through digestion of the extracellular matrix and cleavage of bioactive proteins, a huge diversity of roles have been revealed for the MMPs in IBD, where they have been shown to regulate epithelial barrier function, immune response, angiogenesis, fibrosis, and wound healing. For this reason, MMPs have been recognised as potential biomarkers for disease activity in IBD and inhibition remains a huge area of interest. This review describes new roles of MMPs in the pathophysiology of IBD and suggests future directions for the development of treatment strategies in this condition.

Diplacone and mimulone ameliorate dextran sulfate sodium-induced colitis in rats

Diplacone (1) and mimulone (2), two geranylated flavanones, have previously shown anti-inflammatory and antiradical activity in vitro. The present study aimed to evaluate their activity in vivo on a model of colitis induced in Wistar rats by an oral administration of dextran sulfate sodium (DSS). Diplacone (1) and mimulone (2) were administered at a bolus dose of 25mg/kg by gastric gavage 48 and 24h prior to the induction of colitis by DSS and every 24h on the following days of the experiment. The effect of the treatment was assessed by monitoring the disease activity index (DAI), histopathological examination, evaluation of the weight and length of the colon and by analysis of the levels and activities of cyclooxygenase-2 (COX-2), matrix metalloproteinase-2 (MMP2), superoxide dismutase-2 (SOD2), and catalase (CAT) in the inflamed tissue. Administration of the test compounds prior and after induction of colitis ameliorated the symptoms of colitis (diarrhea, presence of the blood in the stool) and delayed their onset. The ability of compounds 1 and 2 to reduce the levels of COX-2 and to increase the ratio of pro-MMP2/MMP2 activity correlates with the values of the DAI. The lowering of the levels of the antioxidant enzymes SOD2 and CAT reflects the ability of the test compounds to scavenge reactive oxygen species.

Selective gelatinase inhibition reduces apoptosis and pro-inflammatory immune cell responses in Campylobacter jejuni-infected gnotobiotic IL-10 deficient mice

Increased levels of the matrix metalloproteinases-2 and -9 (also referred to gelatinase-A and -B, respectively) can be detected in intestinal inflammation. We have recently shown that selective gelatinase blockage by the synthetic compound RO28-2653 ameliorates acute murine ileitis and colitis. We here investigated whether RO28-2653 exerts anti-inflammatory effects in acute Campylobacter jejuni-induced enterocolitis of gnotobiotic IL-10(-/-) mice generated following antibiotic treatment. Mice were perorally infected with C. jejuni (day 0) and either treated with RO28-2653 (75 mg/kg body weight/day) or placebo from day 1 until day 6 post infection (p.i.) by gavage. Irrespective of the treatment, infected mice displayed comparable pathogen loads within the gastrointestinal tract. Following RO28-2653 administration, however, infected mice exhibited less severe symptoms such as bloody diarrhea as compared to placebo controls. Furthermore, less distinct apoptosis but higher numbers of proliferating cells could be detected in the colon of RO28-2653-treated as compared to placebo-treated mice at day 7 p.i. Remarkably, gelatinase blockage resulted in lower numbers of T- and B-lymphocytes as well as macrophages and monocytes in the colonic mucosa of C. jejuni-infected gnotobiotic IL-10(-/-) mice. Taken together, synthetic gelatinase inhibition exerts anti-inflammatory effects in experimental campylobacteriosis.

Pituitary adenylate cyclase-activating polypeptide ameliorates experimental acute ileitis and extra-intestinal sequelae

Background

The neuropeptide Pituitary adenylate cyclase-activating polypeptide (PACAP) plays pivotal roles in immunity and inflammation. So far, potential immune-modulatory properties of PACAP have not been investigated in experimental ileitis.

Methodology/Principal Findings

Mice were perorally infected with Toxoplasma (T.) gondii to induce acute ileitis (day 0) and treated daily with synthetic PACAP38 from day 1 to 6 post infection (p.i.; prophylaxis) or from day 4 to 6 p.i. (therapy). Whereas placebo-treated control mice suffered from acute ileitis at day 7 p.i. and succumbed to infection, intestinal immunopathology was ameliorated following PACAP prophylaxis. PACAP-treated mice exhibited increased abundance of small intestinal FOXP3+ cells, but lower numbers of ileal T lymphocytes, neutrophils, monocytes and macrophages, which was accompanied by less ileal expression of pro-inflammatory cytokines such as IL-23p19, IL-22, IFN-γ, and MCP-1. Furthermore, PACAP-treated mice displayed higher anti-inflammatory IL-4 concentrations in mesenteric lymph nodes and liver and higher systemic anti-inflammatory IL-10 levels in spleen and serum as compared to control animals at day 7 p.i. Remarkably, PACAP-mediated anti-inflammatory effects could also be observed in extra-intestinal compartments as indicated by reduced pro-inflammatory mediator levels in spleen (TNF-α, nitric oxide) and liver (TNF-α, IFN-γ, MCP-1, IL-6) and less severe histopathological sequelae in lungs and kidneys following prophylactic PACAP treatment. Strikingly, PACAP prolonged survival of T. gondii infected mice in a time-of-treatment dependent manner.

Conclusion/Significance

Synthetic PACAP ameliorates acute small intestinal inflammation and extra-intestinal sequelae by down-regulating Th1-type immunopathology, reducing oxidative stress and up-regulating anti-inflammatory cytokine responses. These findings provide novel potential treatment options of inflammatory bowel diseases.

The synthetic hydroxyproline-containing collagen analogue (Gly-Pro-Hyp)10 ameliorates acute DSS colitis

In experimental models of and humans with intestinal inflammation, increased levels of the matrix-degrading gelatinases MMP-2 and -9 in inflamed tissues can be detected. The synthetic collagen analogue (Gly-Pro-Hyp)10, (GPO)10, has been identified as a relevant binding structure for proMMP-2/-9 and promotes enzymatic activity of proMMP-2. Since targeted MMP strategies might offer promising anti-inflammatory treatment options, we for the first time studied in vivo actions exerted by (GPO)10 applying an acute dextrane sulfate sodium (DSS) induced colitis model. Seven-day intraperitoneal (GPO)10 treatment ameliorated clinical symptoms and histopathological colonic changes as compared to placebo controls with severe colitis. (GPO)10-treated mice displayed a diminished influx of neutrophils, and T- and B-lymphocytes into their colonic mucosa whereas numbers of regulatory T-cells and regenerative cells were higher as compared to placebo controls. Furthermore, IL-6 secretion was down-regulated in ex vivo colonic biopsies derived from (GPO)10-treated mice whereas higher concentrations of the anti-inflammatory cytokine IL-10 in extra-intestinal compartments such as MLN and spleen could be detected. Strikingly, influx of inflammatory cells into lungs was abolished following (GPO)10 application. We therefore propose (GPO)10 as a promising effective and safe treatment option of intestinal and extra-intestinal inflammatory conditions in humans.

The synthetic hydroxyproline-containing collagen analogue (Gly-Pro-Hyp)10 promotes enzymatic activity of matrixmetalloproteinase-2 in vitro

Diseases such as liver fibrosis and intestinal inflammation are characterized by accumulated components of the extracellular matrix (ECM). Given that fibrillar collagen structures were shown to serve as storage site for inactive proforms of matrixmetalloproteinases (MMPs), modulating this MMP-collagen interaction might offer a rational interventional (therapeutic) approach to enhance degradation of accumulated ECM. The synthetic triple helical collagen analogue (Gly-Pro-Hyp)10 - (GPO)10 - was shown to trigger release and enzymatic activation of collagen sequestered proMMP-2. In the presented study, we, for the first time, investigated how MMP-(GPO)10 interaction impacts cellular responses in vitro. We found that recombinant proMMP-2 induced proliferation of hepatic stellate cells (HSC), which was enhanced after addition of (GPO)10 reaching comparable levels following incubation with fully activated MMP-2. In addition, (GPO)10 induced HSC migration similar to the platelet-derived growth factor subunit-B. Further, the MMP-2-dependent invasion of HT1080 fibrosarcoma cells through an ECM membrane was enhanced after addition of (GPO)10. Since cellular proliferation and migration concomitant with matrix degradation is stimulated, we conclude that the MMP-(GPO)10 interaction also functions in a physiological environment. Thus, a potential therapeutic effect of (GPO)10 should be further tested in animal models for MMP-associated diseases such as colitis or fibrosis.

The distinct roles of MMP-2 and MMP-9 in acute DSS colitis

Expression of gelatinases A and B, also referred to matrixmetalloproteinases (MMP)-2 and -9, respectively, is increased in inflamed tissues of experimental intestinal inflammation and humans with inflammatory bowel disease (IBDs). Given that we recently reported that treatment with the selective gelatinase inhibitor RO28-2653 ameliorates acute dextrane sulfate sodium (DSS) colitis, we asked whether gelatinase A or B expression is pivotal in mediating large intestinal inflammation. Results from our study reveal that symptoms of acute DSS colitis as well as histopathological colonic changes were ameliorated in MMP-2-, but not MMP-9-deficient mice, and were paralleled by a diminished influx of immune cells. In MMP-2-deficient mice, we observed lower expression of pro-inflammatory cytokines including interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), and IL-6 in colonic biopsies and less overgrowth of the colonic lumen by potentially pro-inflammatory enterobacteria from the commensal gut microbiota. We conclude that rather MMP-2 than MMP-9 is causative for the establishment of DSS colitis in mice. The discrepancy of these data to prior reports might be due to substantial differences in the intestinal microbiota composition of the mice bred at different animal facilities impacting susceptibility to inflammatory stimuli. Consequently, a detailed survey of the gut microbiota should be implemented in immunological/inflammatory studies in the future in order to allow comparison of data from different facilities.