Intestinal recruiting and activation profiles in peripheral blood mononuclear cells in response to pathogen-associated molecular patterns stimulation in patients with IBS.
BACKGROUND
Immune activation, increased Toll-like Receptors (TLR) expression, and gut epithelial diffusion of bacterial molecules have been reported in irritable bowel syndrome (IBS). Thus, we sought to relate these factors by analyzing gut homing (integrin α4β7), intestinal recruiting (CCR5) and activation (CD28) phenotypes, and the cytokines and chemokines concentration in peripheral blood T-lymphocytes stimulated with TLR-ligands.


METHODS
Twenty-one IBS-Rome II (1 PI-IBS) patients and 19 controls were studied. Isolated peripheral blood mononuclear cells were cultured with and without Escherichia coli lipopolysaccharide (LPS), Staphylococcus aureus peptidoglycan (PGN), and unmethylated cytosine-phosphate-guanine motifs (CpG). Phenotypes were investigated by flow cytometry and supernatant cytokines and chemokines were also measured.


RESULTS
After LPS, CCR5 expression in CD4⁺ α4β7⁺ cells remained unchanged in IBS, but decreased in controls (p = 0.002), to lower levels than in IBS (Mean fluorescence intensity [MFI]: 1590 ± 126.9 vs 2417 ± 88.4, p < 0.001). There were less CD8(+) α4β7⁺ CCR5⁺ cells (85.7 ± 1.5 vs 90.8 ± 0.9%, p = 0.006) after LPS and CD3⁺ α4β7⁺ CCR5⁺ (40.0 ± 1.7 vs 51.2 ± 4.3%, p = 0.006) after PGN in controls. Also, after LPS, CD28 decreased in CD4⁺ α4β7⁺ CCR5⁺ in IBS (MFI: 2337 ± 47.2 vs 1779 ± 179.2, p < 0.001), but not in controls. Cytokines and chemokines were similar, except for lower IL8/CXCL8 in the unstimulated condition in IBS (4.18, 95% CI: 3.94-4.42 vs 3.77, 3.59-3.95; p = 0.006).


CONCLUSIONS
Pathogen-associated molecular patterns stimulation of peripheral blood T cells expressing gut homing marker in IBS compared with controls resulted in an unsuccessful down-regulation of the co-expression of intestinal recruiting/residence phenotype and a state of activation. These findings support an interaction between an innate immune predisposition and microbial triggers, which may unleash or exacerbate IBS.
Laboratorio de Hígado, Páncreas y Motilidad (HIPAM), Departamento de Medicina Experimental, Facultad de Medicina-Universidad Nacional Autónoma de México (UNAM), Hospital General de México, México Distrito Federal, México.
O
O
Rodríguez-Fandiño
J
J
Hernández-Ruíz
Y
Y
López-Vidal
L
L
Charúa
H
H
Bandeh-Moghaddam
A
A
Minzoni
C
C
Guzmán
M
M
Schmulson
D000328:Adult; D018106:CD28 Antigens / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D004926:Escherichia coli / Q000276:immunology; D005260:Female; D006801:Humans; D016023:Integrins / Q000378:metabolism; D043183:Irritable Bowel Syndrome / Q000209:etiology / Q000276:immunology*; D008297:Male; D019713:Receptors, CCR5 / Q000378:metabolism; D013211:Staphylococcus aureus / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D051193:Toll-Like Receptors / Q000378:metabolism*
D018106:CD28 Antigens; D016207:Cytokines; D016023:Integrins; D019713:Receptors, CCR5; D051193:Toll-Like Receptors; C071777:integrin alpha4beta7
CpG; chemokines; cytokines; gut homing, residence, activated T cells; innate immunity; irritable bowel syndrome; lipopolysaccharide; peptidoglycan; toll-like receptors