Systemic levels of human β-defensin 1 are elevated in patients with cirrhosis

BACKGROUND

Bacterial translocation (BT) commonly occurs in cirrhosis. Reliable biomarkers for BT are currently lacking. Human beta defensin-1 (hBD-1) is a member of the family of natural antimicrobial peptides produced by epithelial cells and participates in the mucosal defensive mechanisms that prevent BT. The aim of the present study was to examine the local and systemic expression of hBD-1 in patients with cirrhosis.

METHODS

Plasma concentrations of hBD-1 and of soluble CD14 (sCD14) proteins were measured by ELISA in patients with chronic viral hepatitis, cirrhosis, and healthy controls. Relative mRNA expression of various natural antimicrobial peptides was determined by real-time PCR in biopsies from the terminal ileum and colon.

RESULTS

We found significant upregulation of hBD-1 and sCD14 in the peripheral blood of patients with cirrhosis compared to patients with chronic viral hepatitis and healthy controls. The etiology of cirrhosis did not affect the concentration of either protein. The levels of hBD-1 protein correlated significantly with the levels of sCD14 in blood collected from hepatic veins of cirrhotic patients. In contrast, no significant differences were observed in the intestinal mucosal mRNA expression of the Paneth cell specific defensin A5 or hBD-1 between patients with cirrhosis and healthy controls.

CONCLUSIONS

hBD-1 is upregulated in patients with cirrhosis and highly correlates with the lipopolysaccharide-induced protein sCD14. hBD-1 may serve as a biomarker of BT in patients with cirrhosis.

Markers of bacterial translocation in end-stage liver disease

Bacterial translocation (BT) refers to the passage of viable bacteria or bacterial products from the intestinal lumen, through the intestinal epithelium, into the systemic circulation and extraintestinal locations. The three principal mechanisms that are thought to be involved in BT include bacterial overgrowth, disruption of the gut mucosal barrier and an impaired host defence. BT is commonly observed in liver cirrhosis and has been shown to play an important role in the pathogenesis of the complications of end stage liver disease, including infections as well as hepatic encephalopathy and hepatorenal syndrome. Due to the importance of BT in the natural history of cirrhosis, there is intense interest for the discovery of biomarkers of BT. To date, several such candidates have been proposed, which include bacterial DNA, soluble CD14, lipopolysaccharides endotoxin, lipopolysaccharide-binding protein, calprotectin and procalcitonin. Studies on the association of these markers with BT have demonstrated not only promising data but, oftentimes, contradictory results. As a consequence, currently, there is no optimal marker that may be used in clinical practice as a surrogate for the presence of BT.

Transgelin Up-Regulation in Obstructive Nephropathy

Fibrosis is a complex and multifactorial process, affecting the structure and compromising the function of several organs. Among those, renal fibrosis is an important pathological change, eventually leading to renal failure. Proteomic analysis of the renal parenchyma in the well-established rat model of unilateral ureteral obstruction (UUO model) suggested that transgelin was up-regulated during the development of fibrosis. Transgelin up-regulation was confirmed both at the protein and at the mRNA level. It was observed that at early stages of fibrosis transgelin was mainly expressed in the interstitial compartment and, more specifically, in cells surrounding the glomeruli. Subsequently, it was confirmed that transgelin expressing cells were activated fibroblasts, based on their extensive co-expression of α-SMA and their complete lack of co-distribution with markers of other cell types (endothelial, epithelial and cells of the immune system). These periglomerular fibroblasts exhibited staining for transgelin mainly cytoplasmic but occasionally nuclear as well. In addition, transgelin expression in periglomerular fibroblasts was absent in renal fibrosis developed in a hypertensive model, compared to the UUO model. Promoter analysis indicated that there are several conserved motifs for transcription factor binding. Among those, Kruppel-like factor 6 was found to be up-regulated in transgelin positive periglomerular activated fibroblasts, suggesting a possible involvement in the mechanism of transgelin up-regulation. These data strongly suggest that transgelin is up-regulated in the obstructive nephropathy and could be used as a novel marker for renal fibrosis in the future.

Differential expression of the TL1A/DcR3 system of TNF/TNFR-like proteins in large vs. small intestinal Crohn's disease

BACKGROUND

TNF-like cytokine 1A provides co-stimulatory signals to activated lymphocytes through binding to death-domain receptor-3. Decoy receptor-3 inhibits death-domain receptor-3 signalling, rendering immunocytes resistant to apoptosis. These functions may be important for the pathogenesis of Crohn's disease.

AIMS

To study the mucosal and systemic expression of Decoy receptor-3 and TNF-like cytokine 1A in Crohn's disease, in relation to disease activity, localization, and response to treatment.

METHODS

Soluble Decoy receptor-3 and TNF-like cytokine 1A were measured by ELISA in active or quiescent Crohn's disease. Relative mRNA expression in non-affected and inflamed intestinal mucosa was determined by real-time RT-PCR.

RESULTS

We found significant upregulation of Decoy receptor-3 and its ligands TNF-like cytokine 1A and FasL in inflamed intestinal mucosa of Crohn's disease patients. During active disease, Decoy receptor-3 and TNF-like cytokine 1A were detected in the serum in the majority of patients. Intestinal inflammation was strongly associated with these elevations as they were absent during remission and significantly reduced with anti-inflammatory treatment. Regional diversity was observed as Decoy receptor-3 was upregulated in colonic and ileal sites, whereas TNF-like cytokine 1A was preferentially induced in the large bowel mucosa and systemic circulation of patients with colonic involvement.

CONCLUSIONS

TNF-like cytokine 1A and Decoy receptor-3 are upregulated during active Crohn's disease and may participate in disease pathogenesis and offer novel therapeutic opportunities.

Upregulation and nuclear localization of TNF-like cytokine 1A (TL1A) and its receptors DR3 and DcR3 in psoriatic skin lesions

TNF is critically involved in the pathogenesis of psoriasis. TL1A is a TNF-like cytokine, which, after binding to death domain receptor DR3, provides costimulatory signals to lymphocytes, amplifies Th1- and Th17-mediated immune responses and induces apoptotic cell death. These functions are inhibited when TL1A associates to decoy receptor DcR3. In the present study, we investigated the expression profiles for TL1A, DR3 and DcR3 in the normal skin and in psoriatic skin lesions. By use of immunohistochemistry, we were able to demonstrate constitutive cutaneous expression of DR3 and DcR3 but not of TL1A in healthy skin. On the other hand, in patients with active psoriasis, we observed abundant immunostaining for TL1A and significant upregulation of its receptors (P < 0.05 in comparison to healthy skin). TL1A, DR3 and DcR3 proteins, as well as mRNA transcripts reflecting in situ production of TL1A and DcR3, were also specifically increased in lesional as compared to non-lesional skin from patients with psoriasis (P < 0.05). These proteins were upregulated in cell populations that are critically involved in the pathogenesis of chronic skin inflammation, such as keratinocytes, macrophages in deep dermis and cells at the perivascular/endothelial area. Finally, we provide evidence for the existence of nuclear localization of TL1A in inflammatory cells from psoriatic lesions. This was also observed in inflamed synovia from patients with rheumatoid arthritis, but not in neoplastic TL1A-expressing cell lines. We conclude that interactions between TL1A and its two receptors may be involved in the pathogenesis of chronic skin inflammation that takes place in psoriasis.

Cytokines in the pathogenesis of ulcerative colitis

Ulcerative colitis is a chronic inflammatory condition of the large intestine whose etiology remains largely unknown. Its pathogenesis involves the breakdown of intestinal mucosal homeostasis due to a genetically determined miscommunication between commensal flora and the gut associated immune system. Cytokines are central components of the inflammatory pathways that take place during the active and chronic phases of ulcerative colitis. Recent research has identified several novel cytokine systems that are upregulated at the mucosa of patients with ulcerative colitis and started to unveil their functional importance for disease pathogenesis. The significance of interleukin-13 (IL-13), TNF-like cytokine 1A (TL1A), IL-33, and their receptors in ulcerative colitis is strongly supported by converging expression and functional data. These molecular systems may define subgroups of patients with uniform immunological profiles. Within these subpopulations such novel cytokine systems may serve as markers of biological activity of the disease. More importantly, they may offer unique therapeutic opportunities through the development of drugs that specifically target and neutralize well-defined inflammatory pathways.

High intestinal and systemic levels of decoy receptor 3 (DcR3) and its ligand TL1A in active ulcerative colitis

Decoy receptor-3 (DcR3) is a member of the TNF receptor superfamily of proteins, which has been implicated in anti-apoptotic and anti-inflammatory pathways, via binding to TL1A, LIGHT and Fas-L. The role of the TL1A/DcR3 ligand/receptor pair in ulcerative colitis (UC) has not been studied. We investigated the systemic (peripheral blood) and local (large intestine) expression of DcR3 and TL1A in 64 patients with UC and 56 healthy controls. DcR3 serum concentrations were highly elevated in patients with active UC (P<0.0001 vs. healthy controls). This elevation was clearly related to the presence of intestinal inflammation as it was less frequently observed in patients in remission (P=0.003 vs. active UC) whereas effective treatment resulted in disappearance or significant decrease of serum DcR3 (P=0.006 vs. pre-treatment). Furthermore, DcR3 mRNA transcripts were significantly elevated in inflamed areas of the colon (P=0.002 vs. non-affected of the same patient). In addition to DcR3 elevation, we found increased circulating levels of TL1A in patients with either active or inactive UC in comparison to healthy controls (P<0.001 for both). We conclude that elevated serum DcR3 may serve as an indicator of active colonic inflammation in patients with UC. TL1A/DcR3-mediated pathways may participate in the pathogenesis of UC.