Cell surface-anchored syndecan-1 ameliorates intestinal inflammation and neutrophil transmigration in ulcerative colitis.

Syndecan-1 (SDC1), with a variable ectodomain carrying heparan sulphate (HS) chains between different Syndecans, participates in many steps of inflammatory responses. In the process of proteolysis, the HS chains of the complete extracellular domain can be shed from the cell surface, by which they can mediate most of SDC1's function. However, the exact impact on SDC1 which anchored on the cell surface has not been clearly reported. In our study, we established the models by transfection with the cleavable resistant SDC1 mutant plasmid, in which SDC1 shedding can be suppressed during stimulation. Role of membrane SDC1 in inflammatory pathway, pro-inflammatory cytokine secretion as well as neutrophil transmigration, and how suppressing its shedding will benefit colitis were further investigated. We found that the patients suffered ulcerative colitis had high serum SDC1 levels,presented with increased levels of P65, tumour necrosis factor alpha (TNF-α) and IL-1ß and higher circulating neutrophils. NF-κB pathway was activated, and secretion of TNF-α, interleukin-1beta (IL-1ß), IL-6 and IL-8 were increased upon lipopolysaccharide stimuli in intestinal epithelial cells. Syndecan-1, via its anchored ectodomain, significantly lessened these up-regulation extents. It also functioned in inhibiting transmigration of neutrophils by decreasing CXCL-1 secretion. Moreover, SDC1 ameliorated colitis activity and improved histological disturbances of colon in mice. Taken together, we conclude that suppression of SDC1 shedding from intestinal epithelial cells relieves severity of intestinal inflammation and neutrophil transmigration by inactivating key inflammatory regulators NF-κB, and down-regulating pro-inflammatory cytokine expressions. These indicated that compenstion and shedding suppression of cytomembrane SDC1 might be the optional therapy for intestinal inflammation.

Syndecan-1 and heparanase: potential markers for activity evaluation and differential diagnosis of Crohn's disease.

BACKGROUND: Syndecan-1 (SDC1) and its endo-beta-D-glucuronidase heparanase (HPA) are implicated in the maintenance of intestinal barrier function, but their detailed functions in Crohn's disease (CD) are not fully investigated. The aim of this study was to determine alteration patterns of SDC1 and HPA and their potential roles in evaluating disease activity and differentiating CD from intestinal tuberculosis (ITB). METHODS: Tissue and serum specimens were obtained from 89 patients, including 15 patients with functional bowel disorders, 18 active patients with ITB, and 56 patients with CD (remission = 19, active = 37). Basic clinical data were collected and routine blood tests were analyzed. SDC1 and HPA were measured by immunohistochemistry, enzyme-linked immunosorbent assay, reverse transcriptase polymerase chain reaction, and western blot. Colonic epithelial cells were incubated with recombinant HPA, tumor necrosis factor alpha (TNF-α), and mycobacterium tuberculosis culture filtrate protein to detect the alterations of SDC1 and HPA. RESULTS: In the CD group, SDC1 was significantly decreased in mucosa and increased in serum, whereas HPA level in both were elevated. Such alterations were associated with clinicopathological features representing disease activity and injury severity and were not available in functional bowel disorder and ITB groups. Recombinant HPA incubation increased soluble SDC1 in culture supernatants (P = 2 × 10(-4)), and low-dose TNF-α effectively enhanced HPA's activity (P = 3 × 10(-6)). Exogenous TNF-α destroyed cellular SDC1 and raised HPA expressions dose dependently, whereas mycobacterium tuberculosis culture filtrate protein showed no effects. CONCLUSIONS: Unique alterations of SDC1 and HPA are shown in both patients with CD and in vitro model. The results indicate SDC1 and HPA are potential markers for CD in evaluating its disease activity and differentiating it from ITB.

Stimulus-dependent impairment of the neutrophil oxidative burst response in lactoferrin-deficient mice.

Lactoferrin (LF) is an iron-binding protein found in milk, mucosal secretions, and the secondary granules of neutrophils in which it is considered to be an important factor in the innate immune response against microbial infections. Moreover, LF deficiency in the secondary granules of neutrophils has long been speculated to contribute directly to the hypersusceptibility of specific granule deficiency (SGD) patients to severe, life-threatening bacterial infections. However, the exact physiological significance of LF in neutrophil-mediated host defense mechanisms remains controversial and has not yet been clearly established in vivo using relevant animal models. In this study, we used lactoferrin knockout (LFKO) mice to directly address the selective role of LF in the host defense response of neutrophils and to determine its contribution, if any, to the phenotype of SGD. Neutrophil maturation, migration, phagocytosis, granule release, and antimicrobial response to bacterial challenge were unaffected in LFKO mice. Interestingly, a stimulus-dependent defect in the oxidative burst response of LFKO neutrophils was observed in that normal activation was seen in response to opsonized bacteria whereas an impaired response was evident after phorbol myristate-13-acetate stimulation. Taken together, these results indicate that although LF deficiency alone is not a primary cause of the defects associated with SGD, this protein does play an immunomodulatory role in the oxidative burst response of neutrophils.