Defensin-Immunology in Inflammatory Bowel Disease

Gastroenterol Clin Biol. 2009 Jun;33 Suppl 3:S137-44.

Defensin-immunology in inflammatory bowel disease.

Wehkamp J, Stange EF, Fellermann K.

Source

Dr. Margarete Fischer-Bosch - Institute of Clinical Pharmacology, and RobertBoschHospital; Internal Medicine I, Auerbachstr. 112, 70376 Stuttgart, Germany.

Abstract

Defensins are endogenous antibiotics with microbicidal activity against Gram-negative and Gram-positive bacteria, fungi, enveloped viruses and protozoa. A disturbed antimicrobial defense, as provided by Paneth- and other epithelial cell defensins, seems to be a critical factor in the pathogenesis of inflammatory bowel diseases. Conspicuously, there is a relative lack of Paneth cell beta-defensins HD-5 and HD-6 in ileal Crohn's disease, both in the absence of a pattern recognition receptor NOD2 mutation and, even more pronounced, in its presence. This deficit is independent of concurrent active inflammation and results in a diminished antibacterial killing by the mucosa. The Crohn's disease mucosa has not only a significant lack in killing different Escherichia coli but also an impaired ability in clearing Staphylococcus aureus as well as anaerobic micro-organisms. Thus, this dysfunction in antibacterial barrier seems to be broad and is not restricted to a single bacterial strain. In addition to directly controlling barrier function, Paneth cell defensins also regulate the composition of the bacterial stool flora. In the majority of patients, the Paneth cell deficiency is mediated by WNT signalling which suggests a disturbed Paneth cell differentiation in ileal Crohn's disease. In contrast, colonic Crohn's disease is characterised by an impaired induction of mucosal beta-defensins, partly due to a low copy number of the beta-defensin gene cluster. Therefore it seems plausible that bacteria take advantage of a niche formed by defensin deficiency. This would represent a paradigm shift in understanding Crohn's disease and provides a target for future therapeutic strategies.

Supplemental Content

J Clin Microbiol. 2004 Mar;42(3):1203-6.

Antibiotic-associated diarrhea accompanied by large-scale alterations in the composition of the fecal microbiota.

Young VB, Schmidt TM.

Source

Department of Microbiology and Molecular Genetics, Infectious Diseases Unit, National Food Safety and Toxicology Center, Michigan State University, East Lansing, Michigan 48824, USA.

Abstract

Alterations in the diversity of the gut microbiota are believed to underlie the development of antibiotic-associated diarrhea (AAD). A molecular phylogenetic analysis was performed to document temporal changes in the diversity of fecal bacteria of a patient who developed AAD. Antibiotic administration was associated with distinct changes in the diversity of the gut microbiota, including a marked decrease in the prevalence of butyrate-producing bacteria. Following the discontinuation of the antibiotic, resolution of diarrhea was accompanied by a reversal of these changes, providing the first direct evidence linking changes in the community structure of the gastrointestinal bacteria with the development of AAD.

Comment in

Rev Gastroenterol Disord. 2004 Fall;4(4):216-7.

Supplemental Content

Antimicrob Agents Chemother. 2010 Jul;54(7):2960-4. Epub 2010 May 10.

Emergence of resistant Klebsiella pneumoniae in the intestinal tract during successful treatment of Klebsiella pneumoniae lung infection in rats.

Kesteman AS, Perrin-Guyomard A, Laurentie M, Sanders P, Toutain PL, Bousquet-Mélou A.

Source

UMR181 Physiopathologie et Toxicologie Expérimentales, INRA, ENVT, Ecole Nationale Vétérinaire de Toulouse, 23 chemin des Capelles, BP 87 614, 31076 Toulouse Cedex 3, France.

Abstract

Antibiotic treatment of lung infections may lead to the emergence of resistance in the gut flora. Appropriate dosing regimens could mitigate this adverse effect. In gnotobiotic rats harboring intestinal Escherichia coli and Enterococcus faecium populations, a lung infection by Klebsiella pneumoniae was instigated with two different sizes of inoculum to represent an early or a late initiation of antibiotic treatment. The rats were treated with marbofloxacin, an expanded-spectrum fluoroquinolone, by a single-shot administration or a fractionated regimen over 4 days. Intestinal bacterial populations were monitored during and after treatment. At the infection site, bacterial cure without any selection of resistance was observed. Whatever the dosage regimen, fluoroquinolone treatment had a transient negative impact on the E. coli gut population but not on that of E. faecium. The intestinal flora was colonized by the pathogenic lung bacteria, and there was the emergence of intestine-resistant K. pneumoniae, occurring more often in animals treated with a single marbofloxacin dose than with the fractionated dose. Bacterial cure without resistance selection at the infection site with fluoroquinolone treatment can be linked to colonization of the digestive tract by targeted pulmonary bacteria, followed by the emergence of resistance.

Supplemental Content

Infect Immun. 2009 Jul;77(7):2691-702. Epub 2009 May 11.

Perturbation of the small intestine microbial ecology by streptomycin alters pathology in a Salmonella enterica serovar typhimurium murine model of infection.

Garner CD, Antonopoulos DA, Wagner B, Duhamel GE, Keresztes I, Ross DA, Young VB, Altier C.

Source

Department of Population Medicine and Diagnostic Sciences, CornellUniversity, Ithaca, NY14853, USA.

Abstract

The small intestine is an important site of infection for many enteric bacterial pathogens, and murine models, including the streptomycin-treated mouse model of infection, are frequently used to study these infections. The environment of the mouse small intestine and the microbiota with which enteric pathogens are likely to interact, however, have not been well described. Therefore, we compared the microbiota and the concentrations of short-chain fatty acids (SCFAs) present in the ileum and cecum of streptomycin-treated mice and untreated controls. We found that the microbiota in the ileum of untreated mice differed greatly from that of the cecum of the same mice, primarily among families of the phylum Firmicutes. Upon treatment with streptomycin, substantial changes in the microbial composition occurred, with a marked loss of population complexity. Characterization of the metabolic products of the microbiota, the SCFAs, showed that formate was present in the ileum but low or not detectable in the cecum while butyrate was present in the cecum but not the ileum. Treatment with streptomycin altered the SCFAs in the cecum, significantly decreasing the concentration of acetate, propionate, and butyrate. In this work, we also characterized the pathology of Salmonella infection in the ileum. Infection of streptomycin-treated mice with Salmonella was characterized by a significant increase in the relative and absolute levels of the pathogen and was associated with more severe ileal inflammation and pathology. Together these results provide a better understanding of the ileal environment in the mouse and the changes that occur upon streptomycin treatment.

Supplemental Content

Arch Intern Med. 2002 Oct 28;162(19):2177-84.

The spectrum of pseudomembranous enterocolitis and antibiotic-associated diarrhea.

Hurley BW, Nguyen CC.

Source

Division of Hospital Internal Medicine, Mayo Clinic, 13400 E Shea Blvd, Scottsdale, AZ 85259, USA.

Abstract

Pseudomembranous (entero)colitis is primarily caused by Clostridium difficile infection. The most common predisposing factor is prior use of antibiotics, including vancomycin and metronidazole, which themselves are therapy for C difficile colitis. Other risk factors have also been described. The presence of C difficile in the gastrointestinal tract leads to a spectrum of manifestations from the asymptomatic carrier state to fulminant colitis. Successful treatment of C difficile colitis requires prompt treatment with appropriate antibiotics, withdrawal of the suspected predisposing antibiotics, and, in rare cases, total colectomy. Preventive measures of adequate infection control and judicious use of antibiotics are necessary means in attempting to control the spread of C difficile infection. Attempts at making an effective human vaccine are currently under way.

Supplemental Content

JPEN J Parenter Enteral Nutr.2006 Sep-Oct;30(5):395-8; discussion 399.

Influences of long-term antibiotic administration on Peyer's patch lymphocytes and mucosal immunoglobulin A levels in a mouse model.

Yaguchi Y, Fukatsu K, Moriya T, Maeshima Y, Ikezawa F, Omata J, Ueno C, Okamoto K, Hara E, Ichikura T, Hiraide H, Mochizuki H, Touger-Decker RE.

Source

Department of Surgery I, NationalDefenseMedicalCollege, Tokorozawa, Japan.

Abstract

BACKGROUND:

Long-term antibiotic administration is sometimes necessary to control bacterial infections during the perioperative period. However, antibiotic administration may alter gut bacterial flora, possibly impairing gut mucosal immunity. We hypothesized that 1 week of subcutaneous (SC) antibiotic injections would affect Peyer's patch (PP) lymphocyte numbers and phenotypes, as well as mucosal immunoglobulin A (IgA) levels.

METHODS:

Sixty-one male Institute of Cancer Research mice were randomized to CMZ (cefmetazole 100 mg/kg, administered SC twice a day), IPM (imipenem/cilastatin 50 mg/kg x 2), and control (saline 0.1 mL x 2) groups. After 7 days of treatment, the mice were killed and their small intestines removed. Bacterial numbers in the small intestine were determined using sheep blood agar plates under aerobic conditions (n = 21). PP lymphocytes were isolated to determine cell numbers and phenotypes (CD4, CD8, alphabetaTCR, gammadeltaTCR, B220; n = 40). IgA levels in the small intestinal and bronchoalveolar washings were also measured with ELISA.

RESULTS:

Antibiotic administration decreased both bacterial number and the PP cell yield compared with the control group. There were no significant differences in either phenotype percentages or IgA levels at any mucosal sites among the 3 groups.

CONCLUSIONS:

Long-term antibiotic treatment reduces PP cell numbers while decreasing bacterial numbers in the small intestine. It may be important to recognize changes in gut mucosal immunityduring long-term antibiotic administration.

Supplemental Content

Sex Transm Infect. 2009 Sep;85(5):348-53. Epub 2009 Mar 26.

Prospective study of correlates of vaginal Lactobacillus colonisation among high-risk HIV-1 seronegative women.

Baeten JM, Hassan WM, Chohan V, Richardson BA, Mandaliya K, Ndinya-Achola JO, Jaoko W, McClelland RS.

Source

Department of Global Health, University of Washington, Seattle, Washington98104, USA.

Abstract

OBJECTIVE:

Vaginal colonisation with Lactobacillus species is characteristic of normal vaginal ecology. The absence of vaginal lactobacilli, particularly hydrogen peroxide (H(2)O(2))-producing isolates, has been associated with symptomatic bacterial vaginosis (BV) and increased risk for HIV-1 acquisition. Identification of factors associated with vaginal Lactobacillus colonisation may suggest interventions to improve vaginal health.

METHODS:

We conducted a prospective cohort study of correlates of vaginal Lactobacillus colonisation among Kenyan HIV-1 seronegative female sex workers. At monthly follow-up visits, vaginal Lactobacillus cultures were obtained. Generalised estimating equations were used to examine demographic, behavioural and medical correlates of Lactobacillus isolation, including isolation of H(2)O(2)-producing strains.

RESULTS:

Lactobacillus cultures were obtained from 1020 women who completed a total of 8896 follow-up visits. Vaginal washing, typically with water alone or with soap and water, was associated with an approximately 40% decreased likelihood of Lactobacillus isolation, including isolation of H(2)O(2)-producing strains. Recent antibiotic use, excluding metronidazole and treatments for vaginal candidiasis, reduced Lactobacillus isolation by approximately 30%. H(2)O(2)-producing lactobacilli were significantly less common among women with Trichomonas vaginalis infection and those who were seropositive for herpes simplex virus type 2. In contrast, H(2)O(2)-producing lactobacilli were significantly more common among women with concurrent vaginal candidiasis.

CONCLUSIONS:

Modifiable biological and behavioural factors are associated with Lactobacillus colonisation in African women. Our results suggest intervention strategies to improve vaginal health in women at high risk for HIV-1.

Supplemental Content

Proc Natl Acad Sci U S A. 2011 Mar 29;108(13):5354-9. Epub 2011 Mar 14.

Microbiota regulates immune defense against respiratory tract influenza A virus infection.

Ichinohe T, Pang IK, Kumamoto Y, Peaper DR, Ho JH, Murray TS, Iwasaki A.

Source

Department of Immunobiology, YaleUniversitySchool of Medicine, New Haven, CT06520, USA.

Abstract

Although commensal bacteria are crucial in maintaining immune homeostasis of the intestine, the role of commensal bacteria in immune responses at other mucosal surfaces remains less clear. Here, we show that commensal microbiota composition critically regulates the generation of virus-specific CD4 and CD8 T cells and antibody responses following respiratory influenza virus infection. By using various antibiotic treatments, we found that neomycin-sensitive bacteria are associated with the induction of productive immune responses in the lung. Local or distal injection of Toll-like receptor (TLR) ligands could rescue the immune impairment in the antibiotic-treated mice. Intact microbiota provided signals leading to the expression of mRNA for pro-IL-1β and pro-IL-18 at steady state. Following influenza virus infection, inflammasome activation led to migration of dendritic cells (DCs) from the lung to the draining lymph node and T-cell priming. Our results reveal the importance of commensal microbiota in regulating immunity in the respiratory mucosa through the proper activation of inflammasomes.

Comment in

Nat Rev Immunol. 2011 May;11(5):304-5.

Supplemental Content

Gut. 2005 Nov;54(11):1546-52. Epub 2005 Jun 29.

Influence of intestinal bacteria on induction of regulatory T cells: lessons from a transfer model of colitis.

Strauch UG, Obermeier F, Grunwald N, Gürster S, Dunger N, Schultz M, Griese DP, Mähler M, Schölmerich J, Rath HC.

Source

Department of Internal Medicine I, University of Regensburg, D-93053 Regensburg, Germany.

Abstract

BACKGROUND:

The resident flora plays a critical role in initiation and perpetuation of intestinal inflammation, as demonstrated in experimental models of colitis where animals fail to develop disease under germ free conditions. However, the importance of exposure to commensal bacteria before the onset of colitis is unclear. Our aim was to investigate the influence of previous exposure of donor animals to bacterial antigens on colitis development using a transfer model.

METHODS:

Clinical course and histology were evaluated after transfer of CD4(+)CD62L(+) lymphocytes from germ free and conventionally housed donor mice into SCID recipients. Cotransfer of CD4(+)CD62L(+) cells with CD4(+)CD62L(- )lymphocytes from both groups of mice was initiated. Lymphocytes were analysed by FACS, polarisation potential of cells determined, and cytokines measured within the supernatant by enzyme linked immunosorbent assay.

RESULTS:

Animals that received cells from germ free donors developed an earlier onset of colitis compared with mice reconstituted with lymphocytes from conventionally housed animals. Additionally, CD4(+)CD62L(- )cells from germ free mice were not able to abrogate colitis induced by cotransfer with CD4(+)CD62L(+) lymphocytes whereas CD4(+)CD62L(- )T cells from normal mice ameliorated disease. The higher percentage of CD4(+)GITR(+) expressing lymphocytes and the production of interleukin 10 after priming by dendritic cells suggests the presence of T(reg) cells within the CD4(+)CD62L(+) lymphocyte subset derived from conventional housed mice and assumes a lack of T(reg) cells within germ free mice.

CONCLUSION:

The results indicate that bacterial antigens are crucial for the generation and/or expansion of T(reg) cells in a healthy individual. Therefore, bacterial colonisation is of great importance in maintaining the immunological balance.

Supplemental Content

Commensal microbiota and CD8+ T cells shape the formation of invariant NKT cells.

Wei B, Wingender G, Fujiwara D, Chen DY, McPherson M, Brewer S, Borneman J, Kronenberg M, Braun J.

Source

Department of Pathology and Laboratory Medicine, DavidGeffenSchool of Medicine, University of California, Los Angeles, CA90095, USA.

Abstract

Commensal bacteria play an important role in formation of the immune system, but the mechanisms involved are incompletely understood. In this study, we analyze CD1d-restricted invariant NKT (iNKT) cells in germfree mice and in two colonies of C57BL/6 mice termed conventional flora and restricted flora (RF), stably bearing commensal microbial communities of diverse but distinct composition. In germfree mice, iNKT cells were moderately reduced, suggesting that commensal microbiota were partially required for the antigenic drive in maintaining systemic iNKT cells. Surprisingly, even greater depletion of iNKT cell population occurred in RF mice. This was in part attributable to reduced RF levels of intestinal microbial taxa (Sphingomonas spp.) known to express antigenic glycosphingolipid products. However, memory and activated CD8(+) T cells were also expanded in RF mice, prompting us to test whether CD8(+) T cell activity might be further depleting iNKT cells. Indeed, iNKT cell numbers were restored in RF mice bearing the CD8alpha(-/-) genotype or in adult wild-type RF mice acutely depleted with anti-CD8 Ab. Moreover, iNKT cells were restored in RF mice bearing the Prf1(-/-) phenotype, a key component of cytolytic function. These findings indicate that commensal microbiota, through positive (antigenic drive) and negative (cytolytic depletion by CD8(+) T cells) mechanisms, profoundly shape the iNKT cell compartment. Because individuals greatly vary in the composition of their microbial communities, enteric microbiota may play an important epigenetic role in the striking differences in iNKT cell abundance in humans and therefore in their potential contribution to host immune status.

Supplemental Content

Eur J Immunol. 2011 May;41(5):1321-33. doi: 10.1002/eji.201040730. Epub 2011 Mar 21.

Secondary CD8+ T-cell responses are controlled by systemic inflammation.

Wirth TC, Martin MD, Starbeck-Miller G, Harty JT, Badovinac VP.

Source

Department of Microbiology, University of Iowa, Iowa City, IA, USA.

Abstract

Repeated infections and experimental prime-boost regimens frequently result in the generation of secondary (2°) CD8(+) T-cell responses. In contrast to primary (1°) CD8(+) T cells, the parameters that influence the abundance and phenotype of 2° effector and memory CD8(+) T-cell populations are largely unknown. Here, we analyze the impact of different booster infections, Ag curtailment, and systemic inflammation on the quality and quantity of secondary CD8(+) T-cell responses. We show that similar to 1° CD8(+) T-cell responses, the phenotype of 2° effector and memory CD8(+) T-cell populations is critically dependent on the nature of the infectious pathogen and the inflammatory milieu early after infection. In addition, systemic inflammation increases the number of 2° effector and memory CD8(+) T cells after booster infections and immunizations. Therefore, our data reveal new means to boost the number of 2° effector and memory CD8(+) T cells in prime-boost regimens and show a surprisingly high degree of plasticity in 2° memory CD8(+) T-cell phenotype that is controlled by systemic inflammation.