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Last updated: 13th August 2010

Defensin carriers for better mucosal immunity in the digestive system.
Froy O, Chapnik N, Nussinovitch A
Institute of Biochemistry, Food Science and Nutrition, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100, Israel.
International journal of pharmaceutics 2010 Jun;393 (1-2):264-268
The innate immunity utilizes a battery of broad-spectrum antibacterial cationic polypeptides named defensins. In humans, defensins are the first line of defense against pathogens, and their expression has been implicated in several diseases. In addition to exerting direct antimicrobial effects, defensins facilitate and amplify innate and adaptive immune responses. HD-5 is a polypeptide that plays a pivotal role in combating bacteria in the digestive system. Our results show that HD-5 can be entrapped within alginate carriers and strengthen their structure without changing their brittleness. In addition, carrier-entrapped HD-5 is released when incubated in buffer and/or stomach-simulating solution and still retains its activity after the release. This incubation also led to a decrease in carrier strength as well as an increase in their brittleness. Nevertheless the carriers did not disintegrate and remained intact throughout the diffusion process. The release of the defensin exhibited a bimodal behavior, suggesting that it was found both in a cross-linked and non-cross-linked form within the carrier. These results indicate that defensins encapsulated within alginate carriers could possibly be used for better mucosal immunity in the digestive system.
Functional characterization of the NF-kappaB binding site in the human NOD2 promoter.
Hu C, Sun L, Hu Y, Lu D, Wang H, Tang S
Department of Pathophysiology, Medical College, Jinan University, Guangzhou, China.
Cell Mol Immunol. 2010 Jul;7(4):288-95.
Nucleotide-binding and oligomerization domain 2 (NOD2), a member of the NOD protein family, plays an important role in innate immunity. In response to pathogen attack, NOD2 stimulates cytokine and defensin production by activating nuclear factor (NF)-kappaB, a key transcription factor responsible for mediating downstream reactions. However, the mechanism linking NOD2 regulation and NF-kappaB activation is poorly understood. Using bioinformatics, we found a completely preserved canonical NF-kappaB binding site in the NOD2 core promoter (-16 to -25 bp) in both humans and chimpanzees. The functional role of this NF-kappaB binding site was investigated using the enhanced green fluorescent protein (EGFP) reporter system, site-directed mutagenesis, the NF-kappaB activation inhibitor (JSH-23) and the chromatin immunoprecipitation (ChIP) assay. The results show that the NF-kappaB binding site is critical for regulation of the NOD2 gene. Either deletion of the NF-kappaB binding elements within the NOD2 promoter or treatment with an NF-kappaB activation inhibitor could lead to a significant loss of NOD2 promoter activity as detected by reporter gene assay. The canonical NF-kappaB binding site was bound by NF-kappaB as determined by the ChIP method. Based on these results, we suggest a positive feedback regulation between NF-kappaB and NOD2, which may represent an efficient mechanism in response to pathogen invasion.
Identification of gene expression profiles correlated to tumor progression in a preclinical model of colon carcinogenesis.
Bousserouel S, Kauntz H, Gossé F, Bouhadjar M, Soler L, Marescaux J, Raul F
University of Strasbourg, Unit of Physiopathology and Translational Research EA 4438, Laboratory of Nutritional Cancer Prevention, Faculty of Medicine, 67091 Strasbourg-Cedex, France.
Int. J. Oncol. 2010 Jun;36 (6):1485-90
The rat azoxymethane (AOM)-induced colon carcinogenesis model provides useful information for understanding human colorectal neoplasia. Here, we used the AOM model to measure the gene expression profiles of biomarkers related to tumor progression. We assessed tumor progression stages by computed tomographic (CT) colonography. Messenger RNAs were isolated from tumors and mucosal samples, and gene expression levels were assessed by real-time quantitative polymerase chain reaction (PCR). We show that early stages of tumor progression are associated with an upregulation of matrix metalloproteinase-7 (MMP-7) and of genes involved in the inflammatory response, including interleukin (IL1beta) and tumor necrosis factor-alpha (TNFalpha). The ratio of B-cell lymphoma/leukemia 2 (Bcl-2)-associated X proteins (Bax) to Bcl-2 transcript (proapototic/antiapoptotic signals) is elevated in early stages of tumor progression (Bax/Bcl-2 >1) and reversed in more advanced stages of tumor development (Bax/Bcl-2 <1). These changes are associated with the reduced expression of TNF-related apoptosis-inducing ligand (TRAIL)-death receptor 5 (DR5) and FAS (also known as CD95) apoptotic receptors. Advanced stages of tumor development are characterized by an increase in MMP-9 expression associated with the upregulation of components of the innate immune system: alpha-defensin 5 (DEF-5) and neutrophil gelatinase-associated lipocalin (NGAL). The identification of specific gene expression profiles that correlate with tumor progression stages, as reported in the present study, may represent an important step in evaluating potential chemopreventive and/or chemotherapeutic agents prior to initiating clinical trials.
The Putative Role of Human Peritoneal Adipocytes in the Fight against Bacteria: Synthesis of the Antimicrobial Active Peptide DEFA1-3.
Paslakis G, Keuneke C, Groene HJ, Schroppel B, Schmid H, Schloendorff D
Institut für Klinische Biochemie der Medizinischen Poliklinik, University of Munich, Munich, Germany.
Nephron. Experimental nephrology 2010 Apr;115 (4):e96-e100
Background: Spontaneous peritonitis is a rather rare event, even in peritoneal dialysis (PD). As defensins are natural antimicrobial peptides, we hypothesized that adipocytes as the major constituents of the omentum could play an important role in protecting against infection by generating defensin (DEFA1-3). Methods: We isolated adipocytes from the omentum majus and conducted qualitative and quantitative RT-PCR and immunohistochemical analyses. Results: For the first time described, we were able to detect DEFA1-3 mRNA in highly purified isolated omental adipocytes. The expression of DEFA1-3 in adipocytes was confirmed on the protein level by immunohistochemistry. Conclusion: Our report of DEFA1-3 expression by human omental adipocytes adds to the role of adipocytes in the primary defense against bacterial infection. This may include PD, where the presence of the catheter as a foreign body and the nonphysiological dialysis solution may require constant defense measures to prevent peritonitis, a hypothesis that will require further testing.
Possible Relationship between Neutrophil Gelatinase-Associated Lipocalin, Hepcidin, and Inflammation in Haemodialysed Patients.
Malyszko J, Malyszko JS, Kozminski P, Koc-Zorawska E, Mysliwiec M, Macdougall I
Department of Nephrology and Transplantology, Medical University, Bialystok, Poland.
Nephron. Clinical practice 2010 Apr;115 (4):c268-c275
Background: Neutrophil gelatinase-associated lipocalin (NGAL) binds small, iron-carrying molecules - siderophores. On the other hand, hepcidin is a small defensin-like peptide produced by hepatocytes, modulated in response to anaemia, hypoxia, or inflammation. We tested the hypothesis that NGAL may be related to hepcidin, not only to iron metabolism, in 182 prevalent haemodialysed patients. Methods: Iron status (iron, total iron-binding capacity, ferritin, total saturation of transferrin, TSAT), complete blood count, creatinine, albumin, serum lipids were assessed using standard laboratory methods. Soluble receptor of transferrin, high-sensitivity C-reactive protein (hsCRP), tumour necrosis factor-alpha, interleukin-6, prohepcidin, hepcidin and NGAL were measured in serum using commercially available kits. Results: Serum NGAL, prohepcidin, hepcidin levels were significantly higher in haemodialysed patients over healthy volunteers (579.11 +/- 213.95 vs. 78.43 +/- 32.21 ng/ml, p < 0.001, 320.54 +/- 182.65 vs. 98.65 +/- 34.32 ng/ml, p < 0.01, 155.30 +/- 94.05 vs. 23.65 +/- 12.76 ng/ml, p < 0.001, respectively). Serum NGAL correlated strongly with residual renal function (r = -0.54, p < 0.001), Kt/V (r = 0.41, p < 0.001), hepcidin (r = -0.28, p < 0.01), serum creatinine (r = 0.63, p < 0.001), iron (r = 0.25, p < 0.01), TSAT (r = 0.30, p < 0.001), ferritin (r = 0.33, p < 0.001), hsCRP (r = 0.32, p < 0.001). In multiple regression analysis, residual renal function, hepcidin, creatinine and hsCRP were predictors of serum NGAL in haemodialysed patients. Conclusions: NGAL is highly induced in dialysed patients. NGAL could reflect both kidney function and iron metabolism. Taking into account the antimicrobial properties of NGAL, further studies are needed to address the role of NGAL in iron metabolism and inflammation in renal failure.
Enhancement of immunomodulatory activity by liposome-encapsulated natural phosphodiester bond CpG-DNA in a human B cell line.
Kim D, Rhee JW, Kwon S, Kim YE, Choi SY, Park J, Lee Y, Kwon HJ
Department of Microbiology, College of Medicine, Hallym University, Chuncheon 200-702, Korea.
BMB Rep 2010 Apr;43 (4):250-6
Natural phosphodiester bond CpG-DNA that contains immunomodulatory CpG motifs (PO-DNA) upregulates the expression of proinflammatory cytokines and induces an Ag-driven Th1 response in a CG sequence-dependent manner in mice. In humans, only phosphorothioate backbone-modified CpG-DNA (PS-DNA) and not PO-DNA has immunomodulatory activity. In this study, we found that liposome-encapsulated PO-DNA upregulated the expression of human Beta-defensin-2 (hBD-2) and major histocompatibility class II molecules (HLA-DRA) in a CG sequence-dependent and liposome- dependent manner in human B cells. Of the three different liposomes, DOTAP has the unique ability to enhance the immunomodulatory activity of PO-DNA. In contrast, HLA-DRA and hBD-2 promoter activation can be induced by liposomeencapsulated PS-DNA in a CG sequence-independent manner, depending on the CpG-DNA species. Our observations demonstrate that, when encapsulated with a proper liposome in the immune system, natural PO-DNA has the potential to be a useful therapy for the regulation of the innate immune response.
Peroxisome proliferator-activated receptor gamma activation is required for maintenance of innate antimicrobial immunity in the colon.
Peyrin-Biroulet L, Beisner J, Wang G, Nuding S, Oommen ST, Kelly D, Parmentier-Decrucq E, Dessein R, Merour E, Chavatte P, Grandjean T, Bressenot A, Desreumaux P, Colombel JF, Desvergne B, Stange EF, Wehkamp J, Chamaillard M
Institut National de la Santé et de la Recherche Médicale, U795, F-59037 Lille, France.
Proc. Natl. Acad. Sci. U.S.A. 2010 May;107 (19):8772-7
Crohn´s disease (CD), a major form of human inflammatory bowel disease, is characterized by primary immunodeficiencies. The nuclear receptor peroxisome proliferator-activated receptor gamma (PPARgamma) is essential for intestinal homeostasis in response to both dietary- and microbiota-derived signals. Its role in host defense remains unknown, however. We show that PPARgamma functions as an antimicrobial factor by maintaining constitutive epithelial expression of a subset of beta-defensin in the colon, which includes mDefB10 in mice and DEFB1 in humans. Colonic mucosa of Ppargamma mutant animals shows defective killing of several major components of the intestinal microbiota, including Candida albicans, Bacteroides fragilis, Enterococcus faecalis, and Escherichia coli. Neutralization of the colicidal activity using an anti-mDefB10 blocking antibody was effective in a PPARgamma-dependent manner. A functional promoter variant that is required for DEFB1 expression confers strong protection against Crohn´s colitis and ileocolitis (odds ratio, 0.559; P = 0.018). Consistently, colonic involvement in CD is specifically linked to reduced expression of DEFB1 independent of inflammation. These findings support the development of PPARgamma-targeting therapeutic and/or nutritional approaches to prevent colonic inflammation by restoring antimicrobial immunity in CD.
Culture & characterisation of limbal epithelial cells & oral mucosal cells.
Krishnan S, Iyer GK, Krishnakumar S
L & T Department of Ocular Pathology, Vision Research Foundation, Sankara Nethralaya, India.
Indian J. Med. Res. 2010 Mar;131 422-8
BACKGROUND & OBJECTIVES: Sources of autologous tissue that can functionally replace the corneal epithelium have been considered as an alternative to allogenous limbal transplants for limbal stem cells deficiency (LSCD). The aim of the present study was to compare the characterization of oral mucosa with limbal epithelial cells by markers using reverse transcriptase polymerase chain reaction (RT-PCR). METHODS: Experiments were performed using oral tissue (n=6) obtained from patients who underwent oral mucosal graft for LSCD. Confluent cultures of limbus and oral mucosa epithelial cells were characterized by the pututative stem cell markers using RT-PCR. The morphological characteristics of cultivated epithelial cells were analyzed by haematoxylin and eosin staining and phase contrast microscopy. RESULTS: Confluent sheets of epithelial cells were seen at the end of 14(th) day resembling the morphological features of limbal epithelia. RT-PCR analysis showed that cultured oral epithelial cells expressed markers such as ABCG2, p63, delta Np63, isoforms of p63, Keratin 3 (K3), membrane protein--Mucin (MUC 1, 4 and 16) and Antimicrobial Peptide--AMP (Human beta Defensin--hBD 1, 2 and 3). INTERPRETATION & CONCLUSIONS: Oral epithelial cultures have morphological features resembling corneal and limbal epithelial cells by expressing similar marker genes. Thus, feasibility of clinical use of oral epithelial cells need be evaluated for allogenous limbal transplants.
Defensins and cathelicidins in lung immunity.
Tecle T, Tripathi S, Hartshorn KL
Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA.
Innate Immun. 2010;16(3):151-9.
Defensins were first identified in 1985 and are now recognized as part of a large family of antimicrobial peptides, divided into three categories: alpha-, beta-, and -defensins. These defensin classes differ in structure, sites of expression and biological activities. Human alpha-defensins include peptides that are expressed primarily in neutrophils, whereas human beta-defensins are widely expressed in epithelial cells, including those lining the respiratory tract. Defensins were first studied for their broad spectrum activity against bacteria, fungi and viruses; however, it is now clear that they also recruit inflammatory cells and promote innate and adaptive immune responses. Recent evidence shows that defensins have anti-inflammatory effects as well. Hence, defensins can participate in all phases of an immune response in the lung, including initial killing of pathogens and mounting - and resolution -- of an immune or inflammatory response. The cathelicidin, LL-37, is an antimicrobial peptide produced by neutrophils and respiratory epithelial cells that has similar roles in lung immunity as the defensins. A major challenge for the coming years will be to sort out the relative contributions of defensins and LL-37 to overall immune responses in the lung and to determine which of their many in vitro activities are most important for lung immunity.
Genetic variations associated with psoriasis and psoriatic arthritis found by genome-wide association.
Duffin KC, Woodcock J, Krueger GG
4A330 School of Medicine, Salt Lake City, UT 84132, USA.
Dermatol Ther 2010 Mar;23 (2):101-13
Psoriasis and psoriatic arthritis are immune disorders with a complex polygenic basis. HLA-Cw6, which lies in the major histocompatibility region on chromosome 6, is considered the major genetic determinant of psoriasis. Recent genome-wide association studies have identified new variants outside of the MHC with relevance to the immunology of psoriasis. Variants in or near genes that encode subunits of cytokines (IL12B, IL23A) or cytokine receptors (IL23R) are interesting given that the gene product of IL12B, p40, is the target of a recently approved monoclonal antibody therapy for psoriasis (ustekinumab). Association with psoriasis and psoriatic arthritis has been found in TNFAIP3 and TNFIP1, ubiquitin ligases in the NF-kappaB pathway, and IL13, a Th2 cytokine. Copy number variation of human beta-defensin and late cornified envelope genes also associate with psoriasis. Many of these genetic variations also associate with immune disorders considered psoriatic co-morbidities, including Crohn´s disease and diabetes.