Trefoil Factor Family Member 2: From a High-Fat-Induced Gene to a Potential Obesity Therapy Target

Obesity has its epidemiological patterns continuously increasing. With controlling both diet and exercise being the main approaches to manage the energy metabolism balance, a high-fat (HF) diet is of particular importance. Indeed, lipids have a low satiety potential but a high caloric density. Thus, focusing on pharmacologically targetable pathways remains an approach with promising therapeutic potential. Within this context, trefoil factor family member 2 (Tff2) has been characterized as specifically induced by HF diet rather than low-fat diet. TFF2 has also been linked to diverse neurological mechanisms and metabolic patterns suggesting its role in energy balance. The hypothesis is that TFF2 would be a HF diet-induced signal that regulates metabolism with a focus on lipids. Within this review, we put the spotlight on key findings highlighting this line of thought. Importantly, the hypothetical mechanisms pointed highlight TFF2 as an important contributor to obesity development via increasing lipids intestinal absorption and anabolism. Therefore, an outlook for future experimental activities and evaluation of the therapeutic potential of TFF2 inhibition is given. Indeed, its knockdown or downregulation would contribute to an antiobesity phenotype. We believe this work represents an addition to our understanding of the lipidic molecular implications in obesity, which will contribute to develop therapies aiming to manage the lipidic metabolic pathways including the absorption, storage and metabolism via targeting TFF2-related pathways. We briefly discuss important relevant concepts for both basic and clinical researchers.

Trefoil factor-2, an early predictor for acute gastrointestinal injury in patients with acute pancreatitis

Acute gastrointestinal injury (AGI) is commonly present in patients with acute pancreatitis (AP). It is often difficult to predict gastrointestinal function in the early stage due to lack of reliable markers. We aimed to assess whether early plasma trefoil factor 2 (TFF-2) is a potential predictor for AGI.Fifty one patients were included for the onset of AP (from developing abdominal pain) within 72 hours in this prospective observational single-center study from January 2013 to July 2015. Among them 23 patients were classified as mild, 17 as moderately severe, and 11 as severe according to 2012 Atlanta classification. Plasma samples were collected only once at admission to the ICU. Twenty samples of healthy adults were also collected as control. The TFF-2 levels were determined by using a human TFF-2 enzyme-linked immunoassay. AGI grades from 1st to 7th day after admission were observed.The plasma TFF-2 levels among AP patients in early stage were significantly higher than healthy controls (766.41 ng/mL vs 94.37 ng/mL, P < .0001). The correlations between TFF-2 levels and AGI grades from 1st to 4th day after admission were positive (r = 0.47, 0.43, 0.42, 0.40 respectively, P < .05). As a predictor of acute gastrointestinal failure, plasma TFF-2 was superior to others: Acute Physiology and Chronic Health Evaluation II, sequential organ failure assessment, procalcitonin, C-reactive protein, serum calcium. In addition, TFF-2 increased along with the severity of AP (r = 0.554, P < .0001) and associated with Acute Physiology and Chronic Health Evaluation II, sequential organ failure assessment, C-reactive protein, serum calcium.The plasma TFF-2 levels were increased in patients in early stage of AP and correlated with AGI grades and disease severity in our study. TFF-2 might be a potential predictor for acute gastrointestinal failure in patients with AP.

Trefoil Factor Family (TFF) Peptides and Their Links to Inflammation: A Re-evaluation and New Medical Perspectives

Trefoil factor family peptides (TFF1, TFF2, TFF3), together with mucins, are typical exocrine products of mucous epithelia. Here, they act as a gastric tumor suppressor (TFF1) or they play different roles in mucosal innate immune defense (TFF2, TFF3). Minute amounts are also secreted as endocrine, e.g., by the immune and central nervous systems. As a hallmark, TFF peptides have different lectin activities, best characterized for TFF2, but also TFF1. Pathologically, ectopic expression occurs during inflammation and in various tumors. In this review, the role of TFF peptides during inflammation is discussed on two levels. On the one hand, the expression of TFF1-3 is regulated by inflammatory signals in different ways (upstream links). On the other hand, TFF peptides influence inflammatory processes (downstream links). The latter are recognized best in various Tff-deficient mice, which have completely different phenotypes. In particular, TFF2 is secreted by myeloid cells (e.g., macrophages) and lymphocytes (e.g., memory T cells), where it modulates immune reactions triggering inflammation. As a new concept, in addition to lectin-triggered activation, a hypothetical lectin-triggered inhibition of glycosylated transmembrane receptors by TFF peptides is discussed. Thus, TFFs are promising players in the field of glycoimmunology, such as galectins and C-type lectins.

Trefoil Factor Family (TFF) Peptides and Their Diverse Molecular Functions in Mucus Barrier Protection and More: Changing the Paradigm

Trefoil factor family peptides (TFF1, TFF2, TFF3) are typically co-secreted together with mucins. Tff1 represents a gastric tumor suppressor gene in mice. TFFs are also synthesized in minute amounts in the immune and central nervous systems. In mucous epithelia, they support rapid repair by enhancing cell migration ("restitution") via their weak chemotactic and anti-apoptotic effects. For a long time, as a paradigm, this was considered as their major biological function. Within recent years, the formation of disulfide-linked heterodimers was documented for TFF1 and TFF3, e.g., with gastrokine-2 and IgG Fc binding protein (FCGBP). Furthermore, lectin activities were recognized as enabling binding to a lipopolysaccharide of Helicobacter pylori (TFF1, TFF3) or to a carbohydrate moiety of the mucin MUC6 (TFF2). Only recently, gastric TFF1 was demonstrated to occur predominantly in monomeric forms with an unusual free thiol group. Thus, a new picture emerged, pointing to diverse molecular functions for TFFs. Monomeric TFF1 might protect the gastric mucosa as a scavenger for extracellular reactive oxygen/nitrogen species. Whereas, the TFF2/MUC6 complex stabilizes the inner layer of the gastric mucus. In contrast, the TFF3-FCGBP heterodimer (and also TFF1-FCGBP) are likely part of the innate immune defense of mucous epithelia, preventing the infiltration of microorganisms.

Differential Expression of TFF1 and TFF3 in Patients Suffering from Chronic Rhinosinusitis with Nasal Polyposis

Trefoil family factor (TFF) proteins contribute to antimicrobial defense and the maintenance of sinonasal epithelial barrier integrity. Dysregulation of TFF expression may be involved in the development of chronic inflammation and tissue remodeling characteristically found in chronic rhinosinusitis with nasal polyposis (CRSwNP). Expressions of TFF1 and TFF3 were determined in specimens of middle nasal turbinate (MNT-0), bulla ethmoidalis (BE), and nasal polyps (NP) from CRSwNP patients (n = 29) and inferior nasal turbinate from a group of control patients (underwent nasal septoplasty, n = 25). An additional MNT sample was collected 6 months after functional endoscopic sinus surgery (FESS, MNT-6). TFF1 mRNA levels were significantly reduced in all specimens by approximately three- to five-fold, while TFF3 was increased in MNT-0, as compared with controls. Six months after surgery their levels were reversed to control values. CRSwNP patients with S. epidermidis isolated from sinus swabs showed upregulation of TFF3 in MNT and NP as compared with patients with sterile swabs. Target gene regulation was not affected by the presence of type 2 inflammation in patients with confirmed allergy. Results of this study imply participation of TFFs genes in the development of CRSwNP.

Proteomics in gastroparesis: unique and overlapping protein signatures in diabetic and idiopathic gastroparesis

Macrophage-based immune dysregulation plays a critical role in development of delayed gastric emptying in diabetic mice. Loss of anti-inflammatory macrophages and increased expression of genes associated with pro-inflammatory macrophages has been reported in full-thickness gastric biopsies from gastroparesis patients. We aimed to determine broader protein expression (proteomics) and protein-based signaling pathways in gastric biopsies of diabetic (DG) and idiopathic gastroparesis (IG) patients. Additionally, we determined correlations between protein expressions, gastric emptying, and symptoms. Full-thickness gastric antrum biopsies were obtained from nine DG patients, seven IG patients, and five nondiabetic controls. Aptamer-based SomaLogic tissue scan that quantitatively identifies 1,305 human proteins was used. Protein fold changes were computed, and differential expressions were calculated using Limma. Ingenuity pathway analysis and correlations were carried out. Multiple-testing corrected P < 0.05 was considered statistically significant. Seventy-three proteins were differentially expressed in DG, 132 proteins were differentially expressed in IG, and 40 proteins were common to DG and IG. In both DG and IG, "Role of Macrophages, Fibroblasts and Endothelial Cells" was the most statistically significant altered pathway [DG false discovery rate (FDR) = 7.9 × 10^-9; IG FDR = 6.3 × 10^-12]. In DG, properdin expression correlated with GCSI bloating (r = -0.99, FDR = 0.02) and expressions of prostaglandin G/H synthase 2, protein kinase C-ζ type, and complement C2 correlated with 4 h gastric retention (r = -0.97, FDR = 0.03 for all). No correlations were found between proteins and symptoms or gastric emptying in IG. Protein expression changes suggest a central role of macrophage-driven immune dysregulation in gastroparesis, specifically, complement activation in diabetic gastroparesis.NEW & NOTEWORTHY This study uses SOMAscan, a novel proteomics assay for determination of altered proteins and associated molecular pathways in human gastroparesis. Seventy-three proteins were changed in diabetic gastroparesis, 132 in idiopathic gastroparesis compared with controls. Forty proteins were common in both. Macrophage-based immune dysregulation pathway was most significantly affected in both diabetic and idiopathic gastroparesis. Proteins involved in the complement and prostaglandin synthesis pathway were associated with symptoms and gastric emptying delay in diabetic gastroparesis.

ASC and NLRP3 maintain innate immune homeostasis in the airway through an inflammasome-independent mechanism

It is widely accepted that inflammasomes protect the host from microbial pathogens by inducing inflammatory responses through caspase-1 activation. Here, we show that the inflammasome components ASC and NLRP3 are required for resistance to pneumococcal pneumonia, whereas caspase-1 and caspase-11 are dispensable. In the lung of S. pneumoniae-infected mice, ASC and NLRP3, but not caspase-1/11, were required for optimal expression of several mucosal innate immune proteins. Among them, TFF2 and intelectin-1 appeared to be protective against pneumococcal pneumonia. During infection, ASC and NLRP3 maintained the expression of the transcription factor SPDEF, which can facilitate the expression of the mucosal defense factor genes. Moreover, activation of STAT6, a key regulator of Spdef expression, depended on ASC and NLRP3. Overexpression of these inflammasome proteins sustained STAT6 phosphorylation induced by type 2 cytokines. Collectively, this study suggests that ASC and NLRP3 promote airway mucosal innate immunity by an inflammasome-independent mechanism involving the STAT6-SPDEF pathway.

Oxyresveratrol ameliorates ethanol-induced gastric ulcer via downregulation of IL-6, TNF-α, NF-ĸB, and COX-2 levels, and upregulation of TFF-2 levels

Oxyresveratrol, an active ingredient of Artocarpus lakoocha, is known to possess anti-inflammatory and immunomodulatory properties. Current study investigates the immunomodulatory effect of oxyresveratrol in mouse model of ethanol-induced ulcer. Anti-ulcer effect was determined using histopathological evaluation (H&E staining) and different tests like, gastric ulcer scoring, ulcer index, total acid secretion, and gastric pH. The mRNA expression levels of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), nuclear factor-kappaB (NF-ĸB), cyclooxygenase-1 (COX-1), cyclooxygenase-2 (COX-2) and trefoil factor 2 (TFF-2) were evaluated using reverse transcription polymerase chain reaction (RT-PCR). The data showed marked percentage inhibition of erosion, hemorrhage, fibrinoid necrosis, inflammatory infiltrate, and ulcer in low (30 mg/kg b.w.) and high dose (50 mg/kg b.w.) groups of oxyresveratrol. Treatment with oxyresveratrol inhibited ulcer score and ulcer index as compared with disease control group. Oxyresveratrol significantly increased gastric pH (P < 0.001) and attenuated total acid (P < 0.001) secretion. RT-PCR analysis showed significant suppression in the mRNA expression levels of IL-6 (P < 0.001), TNF-α (P < 0.01), NF-ĸB (P < 0.001), and COX-2 (P < 0.05) in oxyresveratrol treated groups, while COX-1 expression levels were found unaltered. Treatment with oxyresveratrol significantly elevated (P < 0.01) the expression levels of cytoprotective TFF-2 levels. Similar Immunomodulatory and anti-ulcer effects were found with ranitidine treatment, which was used as a reference drug. In conclusion, oxyresveratrol possess significant anti-ulcer property which might be attributed to attenuated expression levels of IL-6, TNF-α, NF-ĸB, and COX-2 and elevated expression levels of TFF-2.

TFF2, a MUC6-binding lectin stabilizing the gastric mucus barrier and more (Review)

The peptide TFF2 (formerly 'spasmolytic polypeptide'), a member of the trefoil factor family (TFF) containing two TFF domains, is mainly expressed together with the mucin MUC6 in the gastric epithelium and duodenal Brunner's glands. Pathologically, TFF2 expression is observed ectopically during stone diseases, chronic inflammatory conditions and in several metaplastic and neoplastic epithelia; most prominent being the 'spasmolytic polypeptide-expressing metaplasia' (SPEM), which is an established gastric precancerous lesion. TFF2 plays a critical role in maintaining gastric mucosal integrity and appears to restrain tumorigenesis in the stomach. Recently, porcine TFF2 has been shown to interact with the gastric mucin MUC6 and thus stabilize the gastric mucus barrier. On the one hand, TFF2 binds to MUC6 via non-covalent lectin interactions with the glycotope GlcNAcα1→4Galβ1→R. On the other hand, TFF2 is probably also covalently bound to MUC6 via disulfide bridges. Thus, implications for the complex multimeric assembly, cross-linking, and packaging of MUC6 as well as the rheology of gastric mucus are discussed in detail in this review. Furthermore, TFF2 is also expressed in minor amounts in the immune and nervous systems. Thus, similar to galectins, its lectin activity would perfectly enable TFF2 to form multivalent complexes and cross-linked lattices with a plethora of transmembrane glycoproteins and thus modulate different signal transduction processes. This could explain the multiple and diverse biological effects of TFF2 [e.g., motogenic, (anti)apoptotic, and angiogenic effects]. Finally, a function during fertilization is also possible for TFF domains because they occur as shuffled modules in certain zona pellucida proteins.

Comparison of the anti-ulcer activity between the crude and bran-processed Atractylodes lancea in the rat model of gastric ulcer induced by acetic acid

ETHNOPHARMACOLOGICAL RELEVANCE

The rhizome of Atractylodes lancea (AL, Compositae, Chinese name: Cangzhu; Japanese name: Sou-ju-tsu) has been used traditionally for the treatment of various diseases such as digestive disorders, rheumatic diseases, and influenza in China, Korea and Japan. The crude AL and AL bran-processed are both listed in the Chinese Pharmacopoeia. However, the differences between the effects of the crude and AL bran-processed on gastric ulcer were poorly understood, and the mechanisms for the treatment of gastric ulcer were not clear. This study aimed at comparing the anti-ulcer effects between the crude AL and AL processed in acetic acid induced model in rats and evaluating the mechanisms of action involved in the anti-ulcer properties of AL.

MATERIALS AND METHODS

The model of gastric ulcer was imitated by acetic acid in rats, and AL was gavaged. The serum and gastric tissues were collected. The levels of epidermal growth factor (EGF), trefoil factor2 (TFF2), tumor necrosis factor-α (TNF-α), interleukin 6, 8 (IL-6, 8) and prostaglandin E2 (PGE2) in serum and gastric tissues were determined by the double-antibody sandwich enzyme-linked immunosorbent assay (ELISA), and the mRNA expressions of EGF, TFF2, TNF-α, and IL-8 in stomach were analyzed by quantitative real-time reverse transcription polymerase chain reaction (RT-PCR). Meanwhile, histopathological changes were evaluated by hematoxylin and eosin (HE) stain. The protein expressions of EGF, TFF2, TNF-α, and IL-8 were examined by immunohistochemistry in stomach.

RESULTS

The results demonstrated that the damage of gastric tissue was obviously alleviated and the productions of TNF-α, IL-8, IL-6, and PGE2 and the mRNA expressions of TNF-α, and IL-8 were notably inhibited. Furthermore, the productions of EGF and TFF2 and the mRNA expressions of EGF and TFF2 were significantly stimulated by both crude AL and AL processed in a dose-dependent manner. Compared with the crude AL, the processed AL was more effective.

CONCLUSION

The AL processed had more satisfactory effects in treatment of gastric-ulcer than the crude AL. The anti-ulcer effects of AL could be attributed to the anti-inflammatory properties via down-regulating TNF-α, IL-8, IL-6 and PGE2 and to the gastroprotective effects via up-regulating EGF and TFF2.

Host-derived, pore-forming toxin-like protein and trefoil factor complex protects the host against microbial infection

Aerolysins are virulence factors belonging to the bacterial β-pore-forming toxin superfamily. Surprisingly, numerous aerolysin-like proteins exist in vertebrates, but their biological functions are unknown. βγ-CAT, a complex of an aerolysin-like protein subunit (two βγ-crystallin domains followed by an aerolysin pore-forming domain) and two trefoil factor subunits, has been identified in frogs (Bombina maxima) skin secretions. Here, we report the rich expression of this protein, in the frog blood and immune-related tissues, and the induction of its presence in peritoneal lavage by bacterial challenge. This phenomena raises the possibility of its involvement in antimicrobial infection. When βγ-CAT was administrated in a peritoneal infection model, it greatly accelerated bacterial clearance and increased the survival rate of both frogs and mice. Meanwhile, accelerated Interleukin-1β release and enhanced local leukocyte recruitments were determined, which may partially explain the robust and effective antimicrobial responses observed. The release of interleukin-1β was potently triggered by βγ-CAT from the frog peritoneal cells and murine macrophages in vitro. βγ-CAT was rapidly endocytosed and translocated to lysosomes, where it formed high molecular mass SDS-stable oligomers (>170 kDa). Lysosomal destabilization and cathepsin B release were detected, which may explain the activation of caspase-1 inflammasome and subsequent interleukin-1β maturation and release. To our knowledge, these results provide the first functional evidence of the ability of a host-derived aerolysin-like protein to counter microbial infection by eliciting rapid and effective host innate immune responses. The findings will also largely help to elucidate the possible involvement and action mechanisms of aerolysin-like proteins and/or trefoil factors widely existing in vertebrates in the host defense against pathogens.