Antimicrobial polypeptides of the human colonic epithelium
Introduction
Antimicrobial agents produced by mammalian epithelial cells have become a widely recognized component of innate immunity [4], [21], [28], [67]. Such agents have been found in epithelial cells at many sites, including the skin [18], [54], trachea [13], and gastrointestinal (GI) tract [48]. In the GI tract, much work has focused on the study of the small intestinal Paneth cells, secretory cells that contain several antimicrobial agents including lysozyme, phospholipase A2, and defensins (termed cryptdins in mice)[50]. Paneth cell antimicrobial peptides have been proposed to protect the host from food and water borne sources of microbes [53], [63]. In addition, the lumen of the small intestine is relatively lightly colonized when compared to the large intestine where Paneth cells are not found under normal conditions [50]. This decrease in microbial load may, in part, be a result of the potency of Paneth cell antimicrobial peptides, in combination with other innate defenses of the small intestine [5], [12], [24], [48], [50].
Although the large intestine is in continual, intimate contact with a densely microbe-laden broth [56], infections across the colonic mucosa are relatively rare [32]. This is remarkable, considering that the epithelium separating the microbe-rich lumen from the body’s internal tissues is only a single cell layer thick. Much of the defense of this colonic mucosa is attributed to functions of innate immunity including peristalsis, cell shedding and the physical barrier provided by mucus and epithelial tight junctions [30], [35]. While these mechanisms provide an excellent physical defense, it seems likely that there may also be a chemical or molecular component to the defenses at such a highly colonized site. Therefore, we proposed that antimicrobial agents should exist in the colonic epithelium. Based upon this hypothesis, and upon previous studies addressing this issue from other perspectives [23], [29], [45], we undertook a systematic investigation to isolate such molecules using a functional assay from normal colonic epithelial cells. To the best of our knowledge, this is among the first studies to examine this particular human mucosa at the protein level for the presence of antimicrobial agents.
Section snippets
Colonic tissue
Redundant, surgically resected human colonic tissue was from patients undergoing surgery for cancer. Specimens were processed for routine histological evaluation and tissue samples with normal histology were further studied. Tissue samples were provided by the Cooperative Human Tissue Network, which is funded by the National Cancer Institute. Other investigators may have received specimens from the same subjects. The Cleveland Clinic Foundation Institutional Review Board approved these
Results
Most antimicrobial polypeptides are cationic, a property proposed to promote favorable interaction with negatively charged microbial cell membranes [22]. Examples include members of both the alpha and beta defensin families, many cathelicidins, lysozyme, and secretory phospholipase A2 [6], [19], [37], [67]. Our isolation scheme was designed to employ biochemical techniques to take advantage of this cationic property. The search employed a functional assay to avoid further bias. Additionally,
Discussion
The human colon is the most heavily colonized site in the human body, but infections across its epithelial surface are rather rare. The colon must restrict microbes to the lumen and this containment is, in part, mediated by the colonic epithelium in conjunction with other components of innate and adaptive immunity. Therefore, the colonic epithelium would seem to provide an ideal location to isolate antimicrobial agents. Yet, as discussed below, the colon must also permit the existence of the
Acknowledgements
We thank Dr. Dipankar Ghosh for many helpful discussions on technical aspects of this work. We thank members of the CCF Center for Inflammatory Bowel Diseases—especially B. Shen, V. Fazio, and S. Strong—for help in obtaining tissue specimens used in this study, and Carol de la Motte for help with isolating colonic epithelial cells. We are indebted to Drs. Ghosh and John Crabb for the MALDI-MS analysis reported in this manuscript. This work was supported by the NIH (AI32738) and the American
References (68)
- et al.
Human histone gene organization: nonregular arrangement within a large cluster
Genomic
(1997) - et al.
Characterization of the H1.5 gene completes the set of human H1 subtype genes
Gene
(1997) - et al.
Matrix metalloproteinase 2 is involved in the regulation of the antimicrobial peptide parasin I production in catfish skin mucosa
FEBS Lett
(2002) - et al.
A novel antimicrobial function for a ribosomal peptide from rainbow trout skin
Biochem Biophys Res Commun
(2002) - et al.
Antimicrobial peptides: an emerging concept in cutaneous biology
J Invest Dermatol
(1998) - et al.
The role of cationic antimicrobial peptides in innate host defences
Trends Microbiol
(2000) - et al.
Cationic bactericidal peptides
Adv. Microb. Physiol.
(1995) - et al.
Host defense development in gut and related disorders
Pediatr. Clin. North Am.
(1988) - et al.
Genomic structure and expression of the human fau gene: encoding the ribosomal protein S30 fused to a ubiquitin-like protein
Biochem Biophys Res Commun
(1992) Differences in evolutionary stability among mammalian H1 subtypes. Implications for the roles of H1 subtypes in chromatin
J Biol Chem
(1984)
Monocyte chemotactic factor in rheumatoid arthritis synovial tissue. Probably a cross-linked derivative of S19 ribosomal protein
J Biol Chem
The carboxyl extension of a ubiquitin-like protein is rat ribosomal protein S30
J Biol Chem
Epithelial peptide antibiotics
Biochem Pharmacol
Identification of receptor-binding sites of monocyte chemotactic S19 ribosomal protein dimer
Am J Pathol
Antimicrobial components of vaginal fluid
Am J Obstet Gynecol
Localization of intestinal interleukin-1 activity and protein and gene expression to lamina propria cells
Gastroenterology
Ribosomal protein L30 is dispensable in the yeast Saccharomyces cerevisiae
Mol Cell Biol
Defensins and innate host defence of the gastrointestinal tract
Gut
Peptide antibiotics and their role in innate immunity
Annu. Rev. Immunol
Detection of mRNAs for macrophage products in inflammatory bowel disease by in situ hybridisation
Gut
Clustering of human H1 and core histone genes
Science
Cathepsin D produces antimicrobial peptide parasin I from histone H2A in the skin mucosa of fish
FASEB J
Microheterogeneity in H1 histones and its consequences
Int J Pept Protein Res
Antimicrobial peptides in innate intestinal host defence
Gut
The innate immune response of the respiratory epithelium
Immunol Rev
The gene encoding ribosomal protein S19 is mutated in Diamond–Blackfan anaemia
Nat Genet
Increased expression of antimicrobial peptides and lysozyme in colonic epithelial cells of patients with ulcerative colitis
Clin Exp Immunol
Anti-microbial properties of histone H2A from skin secretions of rainbow trout, Oncorhynchus mykiss
Biochem J
Antimicrobial peptides of phagocytes and epithelia
Semin Hematol
Paneth cell trypsin is the processing enzyme for human defensin-5
Nat. Immunol.
Cell differentiation is a key determinant of cathelicidin LL-37/human cationic antimicrobial protein 18 expression by human colon epithelium
Infect Immun
Ubiquicidin, a novel murine microbicidal protein present in the cytosolic fraction of macrophages
J Leukoc Biol
Cited by (51)
Amphioxus ribosomal proteins RPS15, RPS18, RPS19 and RPS30-precursor act as immune effectors via killing or agglutinating bacteria
2021, Fish and Shellfish ImmunologyCitation Excerpt :This feature makes them, like cationic antimicrobial peptides, easy to interact with negatively charged bacterial surface molecules. Today, more and more ribosomal protein-derived antimicrobial peptides were found, including eukaryotic RPS15 [13], RPS19 [11], RPS23 [14], RPS30 [11], RPL29 [10] and RPL30 [15], as well as prokaryotic RPL1 [28], RPL27 and RPL30 [29]. Here, we show that amphioxus RPS18 has bactericidal activity against Gram-positive bacterium S. aureus (MBC50 = 2 μM) and Gram-negative bacterium E. coli (MBC50 = 1 μM), although a little weaker than that of BjRPS15 (MBC50 is 0.5 μM towards both S. aureus and E. coli).
iTRAQ-based pharmacoproteomics reveals potential targets of berberine, a promising therapy for ulcerative colitis
2019, European Journal of PharmacologyCitation Excerpt :Hist2h2be is a core component of nucleosomes that play a central role in transcriptional regulation, DNA repair, DNA replication, and chromosomal stability. This protein has broad antibacterial activity and may contribute to the formation of a functional antimicrobial barrier by the colonic epithelium (Howell et al., 2003; Tollin et al., 2003). The remarkable down-regulation by DSS and up-regulation by berberine indicates that the antimicrobial barrier is damaged by DSS but repaired following berberine administration, which might partially explain the mechanism of berberine as a multi-target antimicrobial drug, as previously reported (Karaosmanoglu et al., 2014; Avci et al., 2018).
Human colonic mucus is a reservoir for antimicrobial peptides
2013, Journal of Crohn's and Colitis