Galectin-3 expression in pouchitis in patients with ulcerative colitis who underwent ileal pouch-anal anastomosis (IPAA)

Homogalacturonan enriched pectin based hydrogel enhances 6-gingerol's colitis alleviation effect via NF-κB/NLRP3 axis

A nanolipidcarrier (NLC) loaded homogalacturonan enriched pectin (citrus modified pectin, MCP4) hydrogel was designed as a novel colon inflammation site-specific oral delivery system for 6-gingerol (6G) (6G-NLC/MCP4 hydrogel) administration, and its colitis alleviation effect were investigated. 6G-NLC/MCP4 exhibited typical "cage-like" ultrastructure with 6G-NLC embedded in the hydrogel matrix as observed by cryoscanning electron microscope. And due to the homogalacturonan (HG) domain in MCP4 specifically combined with Galectin-3, which is overexpressed in the inflammatory region, the 6G-NLC/MCP4 hydrogel targeted to severe inflammatory region. Meanwhile, the prolonged-release characteristics of 6G-NLC provided sustained release of 6G in severe inflammatory regions. The matrix of hydrogel MCP4 and 6G achieved synergistic alleviation effects for colitis through NF-κB/NLRP3 axis. Specifically, 6G mainly regulated the NF-κB inflammatory pathway and inhibited the activity of NLRP3 protein, while MCP4 regulated the expression of Galectin-3 and peripheral clock gene Rev-Erbα/β to prevent the activation of inflammasome NLRP3.

Metabolic syndrome attenuates ulcerative colitis: Correlation with interleukin-10 and galectin-3 expression

BACKGROUND

Ulcerative colitis (UC) is a chronic disease characterized by inflammation of intestinal epithelium, primarily of the colon. An increasing prevalence of metabolic syndrome (MetS) in patients with UC has been documented recently. Still, there is no evidence that MetS alters the course of the UC.

AIM

To test the influence of the MetS on the severity of UC and the local and systemic immune status.

METHODS

Eighty nine patients with de novo histologically confirmed UC were divided in two groups, according to ATP III criteria: Group without MetS (no MetS) and group with MetS.

RESULTS

Clinically and histologically milder disease with higher serum level of immunosuppressive cytokine interleukin-10 (IL-10) and fecal content of Galectin-3 (Gal-3) was observed in subjects with UC and MetS, compared to subjects suffering from UC only. This was accompanied with predomination of IL-10 over pro-inflammatory cytokines tumor necrosis factor α (TNF-α), interleukin-6 (IL-6), and interleukin-17 (IL-17) in the sera as well as Gal-3 over TNF-α and IL-17 in feces of UC patients with MetS. Further, the patients with both conditions (UC and MetS) had higher percentage of IL-10 producing and Gal-3 expressing innate and acquired immune cells in lamina propria.

CONCLUSION

Local dominance of Gal-3 and IL-10 over pro-inflammatory mediators in patients with MetS may present a mechanism for limiting the inflammatory process and subsequent tissue damage in UC.

Novel potential biomarkers for the diagnosis and monitoring of patients with ulcerative colitis

Unambiguously, great progress has been achieved in the unraveling of more pathological pathways implicated in the development and progression of ulcerative colitis during the last decades. Novel effective drugs that have augmented the management armamentarium have been developed alongside this growing comprehension of the disease, rendering mucosal healing not only a feasible but the optimal goal of every therapy. Clinical evaluation, colonoscopy and biomarkers are the tools used by practitioners for the diagnosis and assessment of the status of the disease in order to achieve clinical remission and mucosal healing for their patients. Among these tools, colonoscopy is the gold method for the cause but is still an invasive, high-cost procedure with possible adverse events such as perforation. While clinical evaluation entails much subjectivity, biomarkers are objective, easily reproducible, non-invasive, cheap and potent surrogate tools of mucosal inflammation. Unfortunately, the well-established, currently in use serum biomarkers, such as C-reactive protein, erythrocyte sedimentation rate and others, do not display sufficiently acceptable sensitivity and specificity rates for the diagnosis of ulcerative colitis and, most importantly, do not represent precisely the mucosal inflammation status of the disease. Therefore, the discovery of new serum biomarkers has been the cause of several studies attempting to discover an "optimal" serum biomarker during the recent years. After thorough research, collection and examination of current data, this review focuses on and selectively presents promising, potential, novel serum biomarkers of ulcerative colitis as they are indicated by studies on the patient over the last years.

Bacterial Flora Play Important Roles in Acute Dextran Sulphate Sodium-Induced Colitis But Are Not Involved in Gal-3 Dependent Modulation of Colon Inflammation

An altered immune response to normal gut microflora is important for the pathogenesis of ulcerative colitis (UC). Galectin- 3 (Gal-3) is an endogenous lectin that plays an important pro-inflammatory role in the induction phase of acute colitis by promoting activation of the NLRP3 infl ammasome and production of IL-1β in macrophages. By using dextran sulphate sodium (DSS) induced colitis, a well-established animal model of UC, we determined whether Gal-3 affects the function of colon infiltrating macrophages by interfering with intestinal microfl ora. Our results showed that genetic deletion of Gal-3 significantly attenuates DSS-induced colitis by down-regulating infiltration of phagocytic cells (neutrophils, macrophages and dendritic cells) in colon tissue of DSS-treated mice, and this correlated with differences in bacterial flora of the gut. Antibiotic treatment attenuates DSS-induced colitis in WT and Gal-3-/- mice without affecting differences between the groups. In conclusion, Gram negative bacterial flora play an important role in DSS-induced acute colitis of mice but are not involved in Gal-3 dependent modulation of colon inflammation.

Galectin-3 Plays an Important Pro-inflammatory Role in the Induction Phase of Acute Colitis by Promoting Activation of NLRP3 Inflammasome and Production of IL-1β in Macrophages

BACKGROUND AND AIMS

Galectin-3 [Gal-3] is an endogenous lectin with a broad spectrum of immunoregulatory effects: it plays an important role in autoimmune/inflammatory and malignant diseases, but the precise role of Gal-3 in pathogenesis of ulcerative colitis is still unknown.

METHODS

We used a model of dextran sulphate sodium [DSS]-induced acute colitis. The role of Gal-3 in pathogenesis of this disease was tested by evaluating disease development in Gal-3 deficient mice and administration of Gal-3 inhibitor. Disease was monitored by clinical, histological, histochemical, and immunophenotypic investigations. Adoptive transfer was used to detect cellular events in pathogenesis.

RESULTS

Genetic deletion or pharmacological inhibition of Gal-3 significantly attenuate DSS-induced colitis. Gal-3 deletion suppresses production of pro-inflammatory cytokines in colonic macrophages and favours their alternative activation, as well as significantly reducing activation of NOD-like receptor family, pyrin domain containing 3 [NLRP3] inflammasome in macrophages. Peritoneal macrophages isolated from untreated Gal-3(-/-) mice and treated in vitro with bacterial lipopolysaccharide or DSS produce lower amounts of tumour necrosis factor alpha [TNF-α] and interleukin beta [IL-1β] when compared with wild type [WT] cells. Genetic deletion of Gal-3 did not directly affect total neutrophils, inflammatory dendritic cells [DCs] or natural killer [NK] T cells. However, the total number of CD11c+ CD80+ DCs which produce pro-inflammatory cytokines, as well as TNF-α and IL-1β producing CD45+ CD11c- Ly6G+ neutrophils were significantly lower in colons of Gal-3(-/-) DSS-treated mice. Adoptive transfer of WT macrophages significantly enhanced the severity of disease in Gal-3(-/-) mice.

CONCLUSIONS

Gal-3 expression promotes acute DSS-induced colitis and plays an important pro-inflammatory role in the induction phase of colitis by promoting the activation of NLRP3 inflammasome and production of IL-1β in macrophages.

Immunohistochemical Studies on Galectin Expression in Colectomised Patients with Ulcerative Colitis

Introduction. The aetiology and pathogenesis of ulcerative colitis (UC) are essentially unknown. Galectins are carbohydrate-binding lectins involved in a large number of physiological and pathophysiological processes. Little is known about the role of galectins in human UC. In this immunohistochemical exploratory study, both epithelial and inflammatory cell galectin expression were studied in patients with a thoroughly documented clinical history and were correlated with inflammatory activity. Material and Methods. Surgical whole intestinal wall colon specimens from UC patients (n = 22) and controls (n = 10) were studied. Clinical history, pharmacological treatment, and modified Mayo-score were recorded. Tissue inflammation was graded, and sections were stained with antibodies recognizing galectin-1, galectin-2, galectin-3, and galectin-4. Results. Galectin-1 was undetectable in normal and UC colonic epithelium, while galectin-2, galectin-3, and galectin-4 were strongly expressed. A tendency towards diminished epithelial expression with increased inflammatory grade for galectin-2, galectin-3, and galectin-4 was also found. In the inflammatory cells, a strong expression of galectin-2 and a weak expression of galectin-3 were seen. No clear-cut correlation between epithelial galectin expression and severity of the disease was found. Conclusion. Galectin expression in patients with UC seems to be more dependent on disease focality and individual variation than on degree of tissue inflammation.

Role of galectins in re-epithelialization of wounds

Re-epithelialization is a critical contributing process in wound healing in the human body. When this process is compromised, impaired or delayed, serious disorders of wound healing may result that are painful, difficult to treat, and affect a variety of human tissues. Recent studies have demonstrated that members of the galectin class of β-galactoside-binding proteins modulate re-epithelialization of wounds by novel carbohydrate-based recognition systems. Galectins constitute a family of widely distributed carbohydrate-binding proteins with the affinity for the β-galactoside-containing glycans found on many cell surface and extracellular matrix (ECM) glycoproteins. There are 15 members of the mammalian galectin family that so far have been identified. Studies of the role of galectins in wound healing have revealed that galectin-3 promotes re-epithelialization of corneal, intestinal and skin wounds; galectin-7 promotes re-epithelialization of corneal, skin, kidney and uterine wounds; and galectins-2 and -4 promote re-epithelialization of intestinal wounds. Promising prospects for developing novel therapeutic strategies for the treatment of problematic, slow- or non-healing wounds are implicit in the findings that galectins stimulate the re-epithelialization of wounds of the cornea, skin, intestinal tract and kidney. Molecular mechanisms by which galectins modulate the process of wound healing are beginning to emerge and are described in this review.

Human intestinal epithelial cells respond to β-glucans via Dectin-1 and Syk

Intestinal epithelial cells (IECs) are the first to encounter luminal antigens and may be involved in intestinal immune responses. Fungi are important components of the intestinal microflora. The potential role of fungi, and in particular their cell wall component β-glucan, in modulating human intestinal epithelial responses is still unclear. Here we examined whether human IECs are capable of recognizing and responding to β-glucans, and the potential mechanisms of their activation. We show that human IECs freshly isolated from surgical specimens, and the human IEC lines HT-29 and SW480, express the β-glucan receptor Dectin-1. The β-glucan-consisting glycans curdlan and zymosan stimulated IL-8 and CCL2 secretion by IEC lines. This was significantly inhibited by a Dectin-1 blockade using its soluble antagonist laminarin. Spleen tyrosine kinase (Syk), a signaling mediator of Dectin-1 activation, is expressed in human IECs. β-glucans and Candida albicans induced Syk phosphorylation, and Syk inhibition significantly decreased β-glucan-induced chemokine secretion from IECs. Thus, IECs may respond to β-glucans by the secretion of pro-inflammatory chemokines in a Dectin-1- and Syk-dependent pathway, via receptors and a signaling pathway described to date only for myeloid cells. These findings highlight the importance of fungi-IEC interactions in intestinal inflammation.

Galectin-3 regulates desmoglein-2 and intestinal epithelial intercellular adhesion

The desmosomal cadherins, desmogleins, and desmocollins mediate strong intercellular adhesion. Human intestinal epithelial cells express the desmoglein-2 isoform. A proteomic screen for Dsg2-associated proteins in intestinal epithelial cells identified a lectin referred to as galectin-3 (Gal3). Gal3 bound to N-linked β-galactosides in Dsg2 extracellular domain and co-sedimented with caveolin-1 in lipid rafts. Down-regulation of Gal3 protein or incubation with lactose, a galactose-containing disaccharide that competitively inhibits galectin binding to Dsg2, decreased intercellular adhesion in intestinal epithelial cells. In the absence of functional Gal3, Dsg2 protein was internalized from the plasma membrane and degraded in the proteasome. These results report a novel role of Gal3 in stabilizing a desmosomal cadherin and intercellular adhesion in intestinal epithelial cells.

FOXP3 expression in duodenal mucosa in pediatric patients with celiac disease

OBJECTIVE

It was the aim of this study to evaluate the number of 2 lymphoid subpopulations, CD8(+) cells and FOXP3(+), in the duodenum mucosa from pediatric celiac patients.

METHODS

Tissue sections prepared from paraffin-embedded biopsies of the descending duodenum of 61 celiac patients with Marsh grade 1 (M1), M2 and M3 disease and biopsies from 21 age-matched non-celiac (NC) patients were immunohistostained with anti-CD8 or FOXP3 antibodies.

RESULTS

The histological Marsh grade correlated with the mean number of FOXP3(+) cells in the lamina propria (LP) mucosa (8.9 ± 1.1, 6.8 ± 2.4, 24.5 ± 2.6 and 31.1 ± 2.8 for NC, M1, M2 and M3 biopsies, respectively; p < 0.001). Using a cutoff point of 15 cells, 95% of NC and 88% of M1 biopsies had a mean of <15 FOXP3(+) cells compared with 14% for M2 and 13% for M3 biopsies. The number of FOXP3(+) cells in the epithelial mucosa also correlated with transglutaminase type 2 serum levels from the celiac patients. Unlike the FOXP3(+) cells, CD8(+) lymphocytes were present in both LP and surface epithelial mucosa and significantly different only in the LP mucosa of the M2 and M3 groups.

CONCLUSION

The number of FOXP3(+) cells is substantially increased in the mucosa of celiac patients at advanced stages. Characterization of the activity of these cells in celiac and in other inflammatory bowel diseases will enable us to understand the significance of these cells in celiac disease.

Matrilysin-1 (MMP7) cleaves galectin-3 and inhibits wound healing in intestinal epithelial cells

BACKGROUND

Galectin-3 is an animal lectin that has been implicated in wound healing and is decreased in inflammatory bowel disease (IBD). Matrix metalloproteinase-7 (MMP7), also known as matrilysin-1, a protease shown to cleave extracellular matrix proteins, is highly expressed in IBD tissues, especially at the leading edge of gastrointestinal ulcers. The ability of MMP7 to cleave galectin-3 and influence wound healing has not been reported previously. The aim was to determine whether MMP7 cleaves galectin-3 and modulates wound healing in intestinal epithelial cells.

METHODS

The cleaved fragments of galectin-3 were identified by N-terminal sequencing and mass spectrometry. Western blotting was used to detect the cleaved galectin-3 products in a colonic epithelial cell line (T84 cells). Cell migration was studied by the in vitro scratch method.

RESULTS

We demonstrate for the first time that MMP7 cleaves galectin-3 in vitro, resulting in three cleaved fragments (20.2 kDa, 18.9 kDa, and 15.5 kDa). Exogenous treatment of T84 cells with recombinant MMP7 resulted in the appearance of secreted galectin-3 cleavage fragments in the supernatant. MMP7 inhibited cell migration and resulted in wound retraction and the addition of MMP7 to galectin-3 abrogated the wound healing and cell migration induced by galectin-3.

CONCLUSIONS

We have demonstrated that galectin-3 is a substrate for MMP7. Cleavage of galectin-3 may be one mechanism by which MMP7 inhibits wound healing. This study has significance in understanding delayed wound healing in chronic intestinal diseases like intestinal ulcers and IBD, where MMP7 protein expression is elevated with a decreased galectin-3 protein expression.