In vitro angiotensin-converting enzyme and interleukin-1 production by epithelioid cells isolated from induced rabbit lung granuloma

Involvement of dendritic cells in sarcoidosis

BACKGROUND

Sarcoidosis is a systemic granulomatous disease of unknown aetiology. It has been suggested that T helper type 1 (Th1) polarisation is associated with the pathophysiology of sarcoidosis, but the mechanism of skewing towards Th1 has not been elucidated. Dendritic cells (DCs) are known to regulate immune responses. This study was performed to determine whether DCs are involved in the aetiology of sarcoidosis.

METHODS

The numbers of peripheral blood DCs in 24 patients with sarcoidosis were analysed and biopsy specimens from four patients were stained immunohistochemically using monoclonal antibodies.

RESULTS

The numbers of both myeloid and lymphoid DC subsets were significantly decreased in the blood and mature DCs were found in the granulomas of patients with sarcoidosis. A number of interferon-gamma (IFN-gamma) producing T cells were also detected in the sarcoid granuloma, as well as many interleukin (IL)-4 producing T cells. Double staining of the biopsy specimen using anti-fascin and anti-CD3 antibodies showed an anatomical interaction between DCs and T cells.

CONCLUSIONS

These findings suggest that the blood DC subsets may migrate into the affected tissues, contributing to the formation of the granulomas in sarcoidosis. It is hypothesised that the migrating DCs may regulate the T cell response in sarcoidosis, at least in the granulomatous lesions.

Identification of IL-1 inhibitory activity as IL-1 receptor antagonist (IL-1ra) in vitro and kinetics of IL-1ra and IL-1 beta in experimental rabbit lung granuloma

This study investigated whether interleukin-1 (IL-1) inhibitory activity in LPS-stimulated culture supernatants of alveolar macrophages and epithelioid cells obtained from rabbit lung granulomas induced by complete Freund's adjuvant (CFA) was identical to IL-1 receptor antagonist (IL-1ra) and examined the changes of IL-1ra and IL-1 beta levels in lung tissue during the natural course of granulomatous inflammation. In the thymocyte proliferation assay, prostaglandin E2 (PGE2)-free culture supernatants from each cell population revealed a bell-shaped IL-1 titration curve with IL-1 activity suppressed at dilutions of 1:1 to 1:2, and gel chromatography of serum-free culture supernatants showed an IL-1 inhibitory peak at 21-25 kD. Suppression of IL-1 activity in the supernatants at lower dilutions and the gel-purified IL-1 inhibitory activity both almost disappeared after IL-1ra depletion with an anti-rabbit IL-1ra immunoaffinity column, indicating that IL-1ra was responsible for this in vitro IL-1 inhibitory activity. Pulmonary tissue levels of IL-1 beta pecked at 24 h (52.0 +/- 9.5 pg/mg) after CFA injection, whereas IL-1ra levels peaked at 4 weeks (23.1 +/- 4.0 ng/mg) when granuloma development was maximal, and the molar excess of IL-1ra to IL-1 beta peaked from 4 weeks onward at over 800-fold. These observations suggest that IL-1ra may be effective for IL-1 regulation, especially in the later stage of granulomatous responses. Immunohistochemical studies demonstrated that the cellular source of IL-1ra within the pulmonary granulomas was mainly epithelioid cells.

Tissue interleukin 1 and interleukin-1 receptor antagonist expression in enterocolitis in resistant and susceptible rats

BACKGROUND/AIMS

Subserosal injection of purified group A streptococcal peptidoglycan-polysaccharide (PG-APS) induces chronic relapsing granulomatous enterocolitis and systemic inflammation in susceptible inbred Lewis rats but only transient intestinal injury in Buffalo and Fischer rats. Cecal interleukin 1 (IL-1) and IL-1 receptor antagonist (IL-1ra) expression was measured in inbred rats displaying differential susceptibility to experimental enterocolitis.

METHODS

The ileum and cecum of Lewis, Buffalo, and Fischer rats were subserosally injected with purified PG-APS or albumin. IL-1 and IL-1ra messenger RNA (mRNA) and protein (IL-1 only) were measured 1 or 27 days later. PG-APS-injected Lewis rats were treated with recombinant human IL-1ra. Kinetics of IL-1 and IL-1ra mRNA expression were studied in peritoneal cells.

RESULTS

All rats strains developed acute inflammation with increased cecal concentrations of IL-1 beta and IL-1ra mRNA. Lewis rats developed chronic enterocolitis and had higher IL-1 and IL-1ra mRNA tissue levels than Buffalo or Fischer rats, which displayed no chronic inflammation. IL-1 beta and IL-1ra were produced by submucosal granulomas and correlated with inflammation. IL-1 alpha protein levels paralleled IL-1 beta mRNA expression. IL-1ra treatment attenuated acute and chronic enterocolitis, adhesions, and arthritis. PG-APS induced IL-1 and IL-1ra expression in peritoneal cells from Lewis and Fischer rats.

CONCLUSIONS

Bacterial cell wall polymers stimulate IL-1 and IL-1ra expression in vivo and in vitro. These counterbalancing cytokines are increased in experimental enterocolitis and have important immunoregulatory roles in intestinal inflammation.

Alpha-naphthyl acetate esterase-1 (ANAE-1) secreted by epithelioid cells from induced rabbit lung granuloma showed MIF activity

The function of alpha-naphthyl acetate esterase-1, whose isoelectric point values range from 5.15 to 5.45, was examined. A higher value of alpha-naphthyl acetate esterase-1 was detected in the extracts of epithelioid cells isolated from rabbit lung granuloma at 4 weeks after injection of Freund's complete adjuvant, compared to those values of alveolar macrophages isolated from the same lungs described above and of the normal lungs. Additionally, this enzyme activity was observed to be prominent in the culture supernatants of epithelioid cells. alpha-Naphthyl acetate esterase-1 was purified from lung granuloma as a single 62-kDa band by SDS-PAGE analysis. The purified enzyme showed a macrophage migration inhibition activity at concentrations over 20 nM, and its activity was dose-dependent. Moreover, when various amounts of the purified enzyme were added to lymphocyte-derived macrophage migration inhibitory factor, macrophage migration inhibition was significantly enhanced with a dose-dependent manner. The results suggest that alpha-naphthyl acetate esterase-1 secreted by granuloma macrophages, particularly by epithelioid cells, contributes to granuloma formation.