Hiutung Chu

Publications of Hiutung Chu

• Bifidobacterium bifidum in a rat model of necrotizing enterocolitis: antimicrobial peptide and protein responses.

  Authors: Mark A Underwood, Anchasa Kananurak, Christine F Coursodon, Camille K Adkins-Reick, Hiutung Chu, Stephen H Bennett, Jan Wehkamp, Patricia A Castillo, Brian C Leonard, Daniel J Tancredi, Michael P Sherman, Bohuslav Dvorak, Charles L Bevins

  Pediatric research. 02/2012;

  Introduction:Necrotizing enterocolitis (NEC) is a devastating disease of premature infants. Probiotics decrease the risk of NEC in clinical and experimental studies. Antimicrobial peptides protectIntroduction:Necrotizing enterocolitis (NEC) is a devastating disease of premature infants. Probiotics decrease the risk of NEC in clinical and experimental studies. Antimicrobial peptides protect the gut against noxious microbes and shape the commensal microbiota, but their role in NEC remains unclear.Methods:To investigate the expression of antimicrobial peptides in experimental NEC and the impact of probiotics on their expression, premature rats were divided into three groups: dam fed (DF), hand fed with formula (FF), or hand fed with formula containing Bifidobacterium bifidum (FF + BIF). All groups were exposed to asphyxia and cold stress.Results:Like in human ontogeny, the rat pup has low expression of Paneth cell antimicrobials, which increases rapidly during normal development. The expression of lysozyme, secretory phospholipase A(2) (sPLA(2)), pancreatic-associated proteins 1 and 3 mRNA was elevated in the FF group with a high incidence of NEC, as compared with the DF and FF + BIF groups where the disease was attenuated.Discussion:We conclude that induction of antimicrobial peptides occurs in experimental NEC similar to that reported in human disease and is attenuated when disease is averted by probiotic B. bifidum. The induction of antimicrobial peptides is likely an adaptive mucosal response that is often not sufficient to prevent disease in the premature gut.

• Expression and activity of a novel cathelicidin from domestic cats.

  Authors: Brian C Leonard, Hiutung Chu, Jennifer L Johns, Richard L Gallo, Peter F Moore, Stanley L Marks, Charles L Bevins

  PloS one. 01/2011; 6(4):e18756.

  Cathelicidins are small cationic antimicrobial peptides found in many species including primates, mammals, marsupials, birds and even more primitive vertebrates, such as the hagfish. Some animalsCathelicidins are small cationic antimicrobial peptides found in many species including primates, mammals, marsupials, birds and even more primitive vertebrates, such as the hagfish. Some animals encode multiple cathelicidins in their genome, whereas others have only one. This report identifies and characterizes feline cathelicidin (feCath) as the sole cathelicidin in domestic cats (Felis catus). Expression of feCath is predominantly found in the bone marrow, with lower levels of expression in the gastrointestinal tract and skin. By immunocytochemistry, feCath localizes to the cytoplasm of neutrophils in feline peripheral blood. Structurally, the mature feCath sequence is most similar to a subgroup of cathelicidins that form linear α-helices. feCath possesses antimicrobial activity against E. coli D31, Salmonella enterica serovar Typhimurium (IR715), Listeria monocytogenes and Staphylococcus pseudintermedius (clinical isolate) similar to that of the human ortholog, LL-37. In contrast, feCath lacks the DNA binding activity seen with LL-37. Given its similarity in sequence, structure, tissue expression, and antimicrobial activity, the cathelicidin encoded by cats, feCath, belongs to the subgroup of linear cathelicidins found not only in humans, but also non-human primates, dogs, mice, and rats.

• Enteric defensins are essential regulators of intestinal microbial ecology.

  Authors: Nita H Salzman, Kuiechun Hung, Dipica Haribhai, Hiutung Chu, Jenny Karlsson-Sjöberg, Elad Amir, Paul Teggatz, Melissa Barman, Michael Hayward, Daniel Eastwood, Maaike Stoel, Yanjiao Zhou, Erica Sodergren, George M Weinstock, Charles L Bevins, Calvin B Williams, Nicolaas A Bos

  Nature immunology. 10/2009;

  Antimicrobial peptides are important effectors of innate immunity throughout the plant and animal kingdoms. In the mammalian small intestine, Paneth cell alpha-defensins are antimicrobial peptidesAntimicrobial peptides are important effectors of innate immunity throughout the plant and animal kingdoms. In the mammalian small intestine, Paneth cell alpha-defensins are antimicrobial peptides that contribute to host defense against enteric pathogens. To determine if alpha-defensins also govern intestinal microbial ecology, we analyzed the intestinal microbiota of mice expressing a human alpha-defensin gene (DEFA5) and in mice lacking an enzyme required for the processing of mouse alpha-defensins. In these complementary models, we detected significant alpha-defensin-dependent changes in microbiota composition, but not in total bacterial numbers. Furthermore, DEFA5-expressing mice had striking losses of segmented filamentous bacteria and fewer interleukin 17 (IL-17)-producing lamina propria T cells. Our data ascribe a new homeostatic role to alpha-defensins in regulating the makeup of the commensal microbiota.

• Lipocalin-2 resistance confers an advantage to Salmonella enterica serotype Typhimurium for growth and survival in the inflamed intestine.

  Authors: Manuela Raffatellu, Michael D George, Yuko Akiyama, Michael J Hornsby, Sean-Paul Nuccio, Tatiane A Paixao, Brian P Butler, Hiutung Chu, Renato L Santos, Thorsten Berger, Tak W Mak, Renée M Tsolis, Charles L Bevins, Jay V Solnick, Satya Dandekar, Andreas J Bäumler

  Cell host & microbe. 06/2009; 5(5):476-86.

  In response to enteric pathogens, the inflamed intestine produces antimicrobial proteins, a process mediated by the cytokines IL-17 and IL-22. Salmonella enterica serotype Typhimurium thrives in theIn response to enteric pathogens, the inflamed intestine produces antimicrobial proteins, a process mediated by the cytokines IL-17 and IL-22. Salmonella enterica serotype Typhimurium thrives in the inflamed intestinal environment, suggesting that the pathogen is resistant to antimicrobials it encounters in the intestinal lumen. However, the identity of these antimicrobials and corresponding bacterial resistance mechanisms remain unknown. Here, we report that enteric infection of rhesus macaques and mice with S. Typhimurium resulted in marked Il-17- and IL-22-dependent intestinal epithelial induction and luminal accumulation of lipocalin-2, an antimicrobial protein that prevents bacterial iron acquisition. Resistance to lipocalin-2, mediated by the iroBCDE iroN locus, conferred a competitive advantage to the bacterium in colonizing the inflamed intestine of wild-type but not of lipocalin-2-deficient mice. Thus, resistance to lipocalin-2 defines a specific adaptation of S. Typhimurium for growth in the inflamed intestine.

• Regulation of C-type lectin antimicrobial activity by a flexible N-terminal prosegment

  Authors: Sohini Mukherjee, Carrie L Partch, Rebecca E Lehotzky, Cecilia V Whitham, Hiutung Chu, Charles L Bevins, Kevin H Gardner, Lora V Hooper

  01/2009; 284:4881-8.

  Members of the RegIII family of intestinal C-type lectins are directly antibacterial proteins that play a vital role in maintaining host-bacterial homeostasis in the mammalian gut, yet little isMembers of the RegIII family of intestinal C-type lectins are directly antibacterial proteins that play a vital role in maintaining host-bacterial homeostasis in the mammalian gut, yet little is known about the mechanisms that regulate their biological activity. Here we show that the antibacterial activities of mouse RegIIIgamma and its human ortholog, HIP/PAP, are tightly controlled by an inhibitory N-terminal prosegment that is removed by trypsin in vivo. NMR spectroscopy revealed a high degree of conformational flexibility in the HIP/PAP inhibitory prosegment, and mutation of either acidic prosegment residues or basic core protein residues disrupted prosegment inhibitory activity. NMR analyses of pro-HIP/PAP variants revealed distinctive colinear backbone amide chemical shift changes that correlated with antibacterial activity, suggesting that prosegment-HIP/PAP interactions are linked to a two-state conformational switch between biologically active and inactive protein states. These findings reveal a novel regulatory mechanism governing C-type lectin biological function and yield new insight into the control of intestinal innate immunity.

• IL-23 orchestrates mucosal responses to Salmonella enterica serotype Typhimurium in the intestine.

  Authors: Ivan Godinez, Manuela Raffatellu, Hiutung Chu, Tatiane A Paixão, Takeshi Haneda, Renato L Santos, Charles L Bevins, Renée M Tsolis, Andreas J Bäumler

  Infection and immunity. 11/2008;

  Salmonella enterica serotype Typhimurium causes an acute inflammatory reaction in the cecum of streptomycin pre-treated mice that involves T cell-dependent induction of interferon (Ifn)-gamma,Salmonella enterica serotype Typhimurium causes an acute inflammatory reaction in the cecum of streptomycin pre-treated mice that involves T cell-dependent induction of interferon (Ifn)-gamma, interleukin (Il)-22 and Il-17 expression. Here we investigated the role of IL-23 in initiating these inflammatory responses using the streptomycin pre-treated mouse model. Compared to wild type mice, expression of Il-17 was abrogated, Il-22 expression was markedly reduced but Ifn-gamma expression was normal in the cecum of IL-23 p19 deficient mice during serotype Typhimurium infection. IL-23 p19 deficient mice also exhibited a markedly reduced expression of regenerating islet-derived 3 gamma (Reg3g), keratinocyte-derived cytokine (Kc), and reduced neutrophil recruitment into the cecal mucosa during infection. Analysis of CD3(+) lymphocytes in the intestinal mucosa by flow cytometry revealed that alphabeta T cells were the predominant cell type expressing the IL-23 receptor in naïve mice. However, a marked increase in the number of IL-23 receptor expressing gammadelta T cells was observed in the lamina propria during serotype Typhimurium infection. Compared to wild type mice, gammadelta T cell receptor deficient mice exhibited blunted expression of Il-17 during serotype Typhimurium infection while Ifn-gamma expression was normal. These data suggested that gammadelta T cells are a significant, but not the sole source of IL-17 in the acutely inflamed cecal mucosa of mice. Collectively our results point to IL-23 as an important player in initiating a T cell-dependent amplification of inflammatory responses in the intestinal mucosa during serotype Typhimurium infection.

• Regional variations in Paneth cell antimicrobial peptide expression along the mouse intestinal tract

  Authors: Jenny Karlsson, Katrin Pütsep, Hiutung Chu, Robert Kays, Charles Bevins, Mats Andersson

  BMC Immunology. 01/2008;

  Abstract Background Enteric antimicrobial peptides secreted from Paneth cells, including α-defensins (in mice named cryptdins), are key effector molecules of innate immunity in the small intestine.Abstract Background Enteric antimicrobial peptides secreted from Paneth cells, including α-defensins (in mice named cryptdins), are key effector molecules of innate immunity in the small intestine. The importance of Paneth cells α-defensins emerged from studies of enteric bacterial infection in genetically modified mice, as well as from recent studies linking reduced levels of these α-defensins to Crohn's disease localized to the ileum. However, analysis of expression of Paneth cell α-defensins is incomplete. We therefore performed a comprehensive evaluation of the distribution of antimicrobial molecules along the mouse small intestinal tract to identify potential variations in regional expression. Results In conventionally reared mice, the repertoire of Paneth cell antimicrobials differs between duodenum and ileum. In contrast to the uniform expression of most Paneth cell antimicrobials, both cryptdin 4 and cryptdin-related sequences (CRS) 4C peptides were expressed at progressively increasing amounts (10¹- and 10⁴-fold, respectively) comparing duodenum and ileum. In tissues other than the small intestine, expression of CRS peptides was noted in thymus and caecum. Most Paneth cell products were also produced in the small intestine of germ-free mice at levels similar to those in controls, however CRS4C and RegIIIγ had reduced levels in the former (3- and 8-fold, respectively). No significant changes in expression levels of Paneth cell antimicrobial peptides was observed after oral challenge with either Salmonella enterica serovar typhimurium or Listeria monocytogenes , supporting current notions on the constitutive nature of this defensive system. Conclusion The repertoire of antimicrobial peptides changes along the small intestinal tract, and a subset of these molecules are up-regulated upon colonization, but not in response to enteric bacterial pathogens. The changes detected upon colonization suggest that Paneth cell antimicrobial peptides may play an important role in commensal microbial homeostasis, in addition to their proposed role in protection against infection. In addition, the differential expression of CRS4C along the small intestine suggests mechanisms of regulation that are distinct from other Paneth cell derived antimicrobial peptides.

• Regional variations in Paneth cell antimicrobial peptide expression along the mouse intestinal tract.

  Authors: Jenny Karlsson, Katrin Pütsep, Hiutung Chu, Robert J Kays, Charles L Bevins, Mats Andersson

  BMC immunology. 01/2008; 9:37.

  Enteric antimicrobial peptides secreted from Paneth cells, including alpha-defensins (in mice named cryptdins), are key effector molecules of innate immunity in the small intestine. The importance ofEnteric antimicrobial peptides secreted from Paneth cells, including alpha-defensins (in mice named cryptdins), are key effector molecules of innate immunity in the small intestine. The importance of Paneth cells alpha-defensins emerged from studies of enteric bacterial infection in genetically modified mice, as well as from recent studies linking reduced levels of these alpha-defensins to Crohn's disease localized to the ileum. However, analysis of expression of Paneth cell alpha-defensins is incomplete. We therefore performed a comprehensive evaluation of the distribution of antimicrobial molecules along the mouse small intestinal tract to identify potential variations in regional expression. In conventionally reared mice, the repertoire of Paneth cell antimicrobials differs between duodenum and ileum. In contrast to the uniform expression of most Paneth cell antimicrobials, both cryptdin 4 and cryptdin-related sequences (CRS) 4C peptides were expressed at progressively increasing amounts (101- and 104-fold, respectively) comparing duodenum and ileum. In tissues other than the small intestine, expression of CRS peptides was noted in thymus and caecum. Most Paneth cell products were also produced in the small intestine of germ-free mice at levels similar to those in controls, however CRS4C and RegIIIgamma had reduced levels in the former (3- and 8-fold, respectively). No significant changes in expression levels of Paneth cell antimicrobial peptides was observed after oral challenge with either Salmonella enterica serovar typhimurium or Listeria monocytogenes, supporting current notions on the constitutive nature of this defensive system. The repertoire of antimicrobial peptides changes along the small intestinal tract, and a subset of these molecules are up-regulated upon colonization, but not in response to enteric bacterial pathogens. The changes detected upon colonization suggest that Paneth cell antimicrobial peptides may play an important role in commensal microbial homeostasis, in addition to their proposed role in protection against infection. In addition, the differential expression of CRS4C along the small intestine suggests mechanisms of regulation that are distinct from other Paneth cell derived antimicrobial peptides.

• The capsule encoding the viaB locus reduces interleukin-17 expression and mucosal innate responses in the bovine intestinal mucosa during infection with Salmonella enterica serotype Typhi.

  Authors: Manuela Raffatellu, Renato L Santos, Daniela Chessa, R Paul Wilson, Sebastian E Winter, Carlos A Rossetti, Sara D Lawhon, Hiutung Chu, Tsang Lau, Charles L Bevins, L Garry Adams, Andreas J Bäumler

  Infection and immunity. 10/2007; 75(9):4342-50.

  The viaB locus contains genes for the biosynthesis and export of the Vi capsular antigen of Salmonella enterica serotype Typhi. Wild-type serotype Typhi induces less CXC chemokine production inThe viaB locus contains genes for the biosynthesis and export of the Vi capsular antigen of Salmonella enterica serotype Typhi. Wild-type serotype Typhi induces less CXC chemokine production in tissue culture models than does an isogenic viaB mutant. Here we investigated the in vivo relevance of these observations by determining whether the presence of the viaB region prevents inflammation in two animal models of gastroenteritis. Unlike S. enterica serotype Typhimurium, serotype Typhi or a serotype Typhi viaB mutant did not elicit marked inflammatory changes in the streptomycin-pretreated mouse model. In contrast, infection of bovine ligated ileal loops with a serotype Typhi viaB mutant resulted in more fluid accumulation and higher expression of the chemokine growth-related oncogene alpha (GROalpha) and interleukin-17 (IL-17) than did infection with the serotype Typhi wild type. There was a marked upregulation of IL-17 expression in both the bovine ligated ileal loop model and the streptomycin-pretreated mouse model, suggesting that this cytokine is an important component of the inflammatory response to infection with Salmonella serotypes. Introduction of the cloned viaB region into serotype Typhimurium resulted in a significant reduction of GROalpha and IL-17 expression and in reduced fluid secretion. Our data support the idea that the viaB region plays a role in reducing intestinal inflammation in vivo.

• Paneth cell antimicrobial peptides: topographical distribution and quantification in human gastrointestinal tissues.

  Authors: Jan Wehkamp, Hiutung Chu, Bo Shen, Ryan W Feathers, Robert J Kays, Sarah K Lee, Charles L Bevins

  FEBS letters. 11/2006; 580(22):5344-50.

  Antimicrobial peptides and proteins are key effectors of innate immunity, expressed both by circulating phagocytic cells and by epithelial cells of mucosal tissues. In the human small intestine,Antimicrobial peptides and proteins are key effectors of innate immunity, expressed both by circulating phagocytic cells and by epithelial cells of mucosal tissues. In the human small intestine, Paneth cells are secretory epithelial cells that express the antimicrobials human alpha-defensin-5 (HD5), HD6, lysozyme and secretory phospholipase A(2) (sPLA(2)), and recent studies have implicated reduced HD5 and HD6 expression levels in the pathogenesis of ileal Crohn's disease. However, expression levels of these molecules have not been determined routinely by techniques that readily permit quantitative comparisons of their distribution between tissues and samples. Using quantitative real-time PCR with external standards and Northern blot analysis, we compared expression levels of mRNA encoding these four Paneth cell antimicrobial peptides, as well as circulating human neutrophil defensins in several different gastrointestinal tissues and the bone marrow. HD5 and HD6 were the most abundant antimicrobials expressed in the small intestine. The concentration of HD5 mRNA is approximately 5 x 10(5) copies per 10ng RNA in the jejunum and ileum; HD6 mRNA levels were about six times lower than those of HD5. With the exception of low levels in the pancreas (10(3) copies/10 ng RNA), the expression of HD5 and HD6 in tissues other than small intestine was at or below detectable limits. The expression of sPLA2 and lysozyme mRNA was observed in the small intestine (approximately, 3 x 10(3) and 9 x 10(3) copies/10 ng RNA, respectively), but also in several other tissues. Lysozyme expression was high in the duodenum (10(5) copies/10 ng RNA), and the protein localized to both Brunner's glands in the lamina propria and Paneth cells. By comparison, the hematopoietic alpha-defensins HNP1-3 mRNA were detected at 6 x 10(5) copies per 10 ng RNA in the bone marrow. These quantitative RT-PCR data from healthy tissues represents the first quantitative topographical assessment of antimicrobial expression in the gastrointestinal tract and provides a means to directly compare expression levels between healthy tissues and disease specimens for multiple antimicrobial peptides.

• Reduced Paneth cell alpha-defensins in ileal Crohn's disease.

  Authors: Jan Wehkamp, Nita H Salzman, Edith Porter, Sabine Nuding, Michael Weichenthal, Robert E. Petras, Bo Shen, Elke Schaeffeler, Matthias Schwab, Rose Linzmeier, Ryan W Feathers, Hiutung Chu, Heriberto Lima, Klaus Fellermann, Tomas Ganz, Eduard F Stange, Charles L Bevins

  Proceedings of the National Academy of Sciences of the United States of America. 01/2006; 102(50):18129-34.

  The pathogenesis of Crohn's disease (CD), an idiopathic inflammatory bowel disease, is attributed, in part, to intestinal bacteria that may initiate and perpetuate mucosal inflammation in geneticallyThe pathogenesis of Crohn's disease (CD), an idiopathic inflammatory bowel disease, is attributed, in part, to intestinal bacteria that may initiate and perpetuate mucosal inflammation in genetically susceptible individuals. Paneth cells (PC) are the major source of antimicrobial peptides in the small intestine, including human alpha-defensins HD5 and HD6. We tested the hypothesis that reduced expression of PC alpha-defensins compromises mucosal host defenses and predisposes patients to CD of the ileum. We report that patients with CD of the ileum have reduced antibacterial activity in their intestinal mucosal extracts. These specimens also showed decreased expression of PC alpha-defensins, whereas the expression of eight other PC products either remained unchanged or increased when compared with controls. The specific decrease of alpha-defensins was independent of the degree of inflammation in the specimens and was not observed in either CD of the colon, ulcerative colitis, or pouchitis. The functional consequence of alpha-defensin expression levels was examined by using a transgenic mouse model, where we found changes in HD5 expression levels, comparable to those observed in CD, had a pronounced impact on the luminal microbiota. Thus, the specific deficiency of PC defensins that characterizes ileal CD may compromise innate immune defenses of the ileal mucosa and initiate and/or perpetuate this disease.