Interleukin-22 receptor 1 is expressed in multinucleated giant cells: A study on intestinal tuberculosis and Crohn's disease

BACKGROUND

It is challenging to distinguish intestinal tuberculosis from Crohn's disease due to dynamic changes in epidemiology and similar clinical characteristics. Recent studies have shown that polymorphisms in genes involved in the interleukin (IL)-23/IL-17 axis may affect intestinal mucosal immunity by affecting the differentiation of Th17 cells.

AIM

To investigate the specific single-nucleotide polymorphisms (SNPs) in genes involved in the IL-23/IL-17 axis and possible pathways that affect susceptibility to intestinal tuberculosis and Crohn's disease.

METHODS

We analysed 133 patients with intestinal tuberculosis, 128 with Crohn's disease, and 500 normal controls. DNA was extracted from paraffin-embedded specimens or whole blood. Four SNPs in the IL23/Th17 axis (IL22 rs2227473, IL1β rs1143627, TGFβ rs4803455, and IL17 rs8193036) were genotyped with TaqMan assays. The transcriptional activity levels of different genotypes of rs2227473 were detected by dual luciferase reporter gene assay. The expression of IL-22R1 in different intestinal diseases was detected by immunohistochemistry.

RESULTS

The A allele frequency of rs2227473 (P = 0.030, odds ratio = 0.60, 95% confidence interval: 0.37-0.95) showed an abnormal distribution between intestinal tuberculosis and healthy controls. The presence of the A allele was associated with a higher IL-22 transcriptional activity (P < 0.05). In addition, IL-22R1 was expressed in intestinal lymphoid tissues, especially under conditions of intestinal tuberculosis, and highly expressed in macrophage-derived Langhans giant cells. The results of immunohistochemistry showed that the expression of IL-22R1 in patients with Crohn's disease and intestinal tuberculosis was significantly higher than that in patients with intestinal polyps and colon cancer (P < 0.01).

CONCLUSION

High IL-22 expression seems to be a protective factor for intestinal tuberculosis. IL-22R1 is expressed in Langhans giant cells, suggesting that the IL-22/IL-22R1 system links adaptive and innate immunity.

[TUBERCULOSIS GRANULOMA: THE CURRENT VIEW OF ITS IMMUNOGENESIS AND CELLULAR COMPOSITION]

The review presents the available basic scientific data characterizing the current views of the immunological homeostasis of intact lung tissue, the population and subpopulation composition of the cells forming a tuberculosis granuloma, as well as their phenotypic characteristics, the factors contributing to macrophageal transformation into epitheliod cells and Pirogov-Langhans giant cells, and the effect of mycobacterial antigens on this process.

NKT cells are critical to initiate an inflammatory response after Pseudomonas aeruginosa ocular infection in susceptible mice

CD4(+) T cells produce IFN-gamma contributing to corneal perforation in C57BL/6 (B6) mice after Pseudomonas aeruginosa infection. To determine the role of NK and NKT cells, infected corneas of B6 mice were dual immunolabeled. Initially, more NKT than NK cells were detected, but as disease progressed, NK cells increased, while NKT cells decreased. Therefore, B6 mice were depleted of NK/NKT cells with anti-asialo GM1 or anti-NK1.1 Ab. Either treatment accelerated time to perforation, increased bacterial load and polymorphonuclear neutrophils, but decreased IFN-gamma and IL-12p40 mRNA expression vs controls. Next, RAG-1 knockout (-/-; no T/NKT cells), B6.TCR Jalpha281(-/-) (NKT cell deficient), alpha-galactosylceramide (alphaGalCer) (anergized NKT cells) injected and IL-12p40(-/-) vs B6 controls were tested. IFN-gamma mRNA was undetectable in RAG-1(-/-)- and alphaGalCer-treated mice at 5 h and was significantly reduced vs controls at 1 day postinfection. It also was reduced significantly in B6.TCR Jalpha281(-/-), alphaGalCer-treated, and IL-12p40(-/-) (activated CD4(+) T cells also reduced) vs control mice at 5 days postinfection. In vitro studies tested whether endotoxin (LPS) stimulated Langerhans cells and macrophages (Mphi; from B6 mice) provided signals to activate NKT cells. LPS up-regulated mRNA expression for IL-12p40, costimulatory molecules CD80 and CD86, NF-kappaB, and CD1d, and addition of rIFN-gamma potentiated Mphi CD1d levels. Together, these data suggest that Langerhans cell/Mphi recognition of microbial LPS regulates IL-12p40 (and CD1d) driven IFN-gamma production by NKT cells, that IFN-gamma is required to optimally activate NK cells to produce IFN-gamma, and that depletion of both NKT/NK cells results in earlier corneal perforation.

Increased susceptibility of mice lacking T-bet to infection with Mycobacterium tuberculosis correlates with increased IL-10 and decreased IFN-gamma production

A sustained CD4+ Th1-dominated type 1 immune response is required to successfully control Mycobacterium tuberculosis infection. Considerable work has demonstrated that the transcription factor, T-bet, is required for IFN-gamma expression and fundamental to the generation of type 1 immunity in multiple cell types. Mice lacking T-bet are susceptible to virulent M. tuberculosis infection. Susceptibility of T-bet-deficient mice is associated with increased systemic bacterial burden, diminished IFN-gamma production, and the striking accumulation of eosinophilic macrophages and multinucleated giant cells in the lung. Interestingly, T-bet(-/-) mice did not develop a fully polarized Th2 response toward M. tuberculosis, but exhibited selective elevation of IL-10 production. These results indicate that T-bet plays a central role in controlling M. tuberculosis disease progression, in part through the regulation of both IFN-gamma and IL-10.

Muramyl dipeptide and mononuclear cell supernatant induce Langhans-type cells from human monocytes

Muramyl dipeptide (MDP) in bacterial cell walls reportedly evokes epithelioid cell granulomas. We examined its effects on multinucleated-giant-cell (MGC) formation from monocytes. Supernatant of concanavalin A-stimulated peripheral blood mononuclear cells (conditioned medium) generated MGCs from monocytes. MDP significantly increased the fusion index of Langhans-type MGCs (LGCs) but did not affect total MGCs. N-Acetylmuramyl-L-alanyl-L-isoglutamine, an MDP analogue, had no effect on MGC formation. MGCs were produced by conditioned medium from CD14(++)/CD16(-) monocytes. MDP enhanced the LGC fusion index from CD14(++)/CD16(-) monocytes. MGCs were not produced from CD14(+)/CD16(+) monocytes or immature dendritic cells induced by granulocyte macrophage-colony stimulating factor (GM-CSF) and interleukin (IL) 4 and only weakly produced from macrophage (M)-CSF- or GM-CSF-induced macrophages. Added MDP did not generate MGCs from CD14(+)/CD16(+) monocytes or dendritic cells but enhanced LGC formation from macrophages. Because IFN-gamma, IL-3, and GM-CSF reportedly are important in LGC induction, we added anti-IFN-gamma, anti-IL-3, or anti-GM-CSF monoclonal antibody (mAb) concomitantly to the monocyte culture treated with conditioned medium alone or plus MDP. Anti-IFN-gamma mAb completely abrogated MGC generation, whereas anti-GM-CSF and anti-IL-3 mAbs significantly inhibited LGCs. These findings suggest that CD14(++)/CD16(-) monocytes are fused to form LGCs by MDP derived from granulomatous-disease-causing pathogens with inflammatory mediators such as IFN-gamma, IL-3, and GM-CSF.