Fecal levels of leukocyte markers reflect disease activity in patients with ulcerative colitis.

OBJECTIVE: A prominent feature of inflammatory bowel disease (IBD) is the presence of inflammatory cells in the gut mucosa, and which contribute to the ongoing inflammatory process. The aim of the study was to evaluate fecal neutrophil, eosinophil, mast cell and macrophage markers in the assessment of disease activity in patients with ulcerative colitis (UC). METHODS: Twenty-eight patients with active UC; 4 with proctitis, 16 with left-side colitis and 8 with total colitis, were included in the study. Patient history, endoscopy and histopathology were examined and fecal and serum samples were evaluated at inclusion and after 4 and 8 weeks of treatment. Fecal samples were analysed for myeloperoxidase (MPO), eosinophil protein X (EPX), mast cell tryptase, IL-1beta and TNF-alpha using immunoassays. Blood samples were analysed for MPO, EPX, C-reactive protein, orosomucoid and leucocyte counts. RESULTS: Fecal MPO and IL-1beta levels were elevated in all patients at inclusion despite different disease extensions. Striking reductions in fecal levels of MPO, EPX, tryptase and IL-1beta were observed after 4 weeks of treatment in 20/28 patients with complete remission after 8 weeks. No further reductions were seen in 20/27 patients at 8 weeks. Endoscopic score correlated to IL-1beta at all visits (p<0.01), to MPO at visits 2 and 3 (p<0.05, p<0.001), EPX at visit 2 (p<0.05) and tryptase at visit 3 (p<0.01). Levels of fecal markers also related to histological indices of the disease. CONCLUSIONS: Measurements of fecal MPO, EPX and IL-1beta could be objective complements to endoscopical and histopathological evaluations in the daily care of patients with UC.

Enhanced interleukin-18 levels in the peripheral blood of children with coeliac disease.

Coeliac disease (CoD) is a small intestinal disorder characterized by villous atrophy, crypt cell hyperplasia and an increased production of T helper cell type 1 (Th1) cytokines. Interleukin (IL)-18 is a pro-inflammatory cytokine that has a crucial role in maintaining the Th1 response. In this study, the serum levels of IL-18 were measured in children with CoD or other gastrointestinal diseases in order to evaluate the possibility of using IL-18 as a disease activity marker. IL-18 levels were higher in samples from CoD patients [median 443 pg/ml (148-885)] compared to healthy controls [median 205 pg/ml (11-379)], P <0.05. In contrast, the levels of IL-18 were not enhanced significantly in the serum from patients with inflammatory bowel disease (IBD) [median 324 pg/ml (207-546)] or in the disease control group [median 303 pg/ml (2-689)]. In CoD patients, after 2 weeks of gluten challenge (GC), serum IL-18 was unchanged [median 268 pg/ml (59-458)] compared to patients on a gluten-free diet [median 220 pg/ml (53-600)], while IL-18 was increased after 12 weeks of GC [median 551 pg/ml (94-952)], P <0.01. The IL-18 levels correlated with IgA anti-transglutaminase antibody levels (rs=0.59, P=0.016) in serum from untreated CoD patients, and IL-18 also followed the degree of small intestinal villous atrophy in 12 out of 19 CoD patients. Our results support the view that serum IL-18 concentrations in children with CoD follow disease activity, suggesting a role for IL-18 in the induction of an inflammatory Th1-response after gluten exposure.

CD4+ T lymphocytes with constitutive CD40 ligand in preautoimmune (NZB x NZW)F1 lupus-prone mice: phenotype and possible role in autoreactivity.

Lupus disease is marked by B lymphocyte hyperactivity and the production of Abs to dsDNA. The production of these anti-dsDNA Abs is T lymphocyte dependent. However, it is not clear how CD4+ T lymphocytes provide help for B lymphocytes to produce IgG anti-dsDNA Abs. One possible mechanism is suggested by studies showing that human patients with systemic lupus erythematosus and lupus mice have increased numbers of CD40 ligand (CD40L)+ T and B lymphocytes. The results described in this study reveal that young, clinically healthy lupus-prone New Zealand Black x New Zealand White F1 (BWF1) mice have naive CD4+ T cells with preformed CD40L. These cells contribute to a brisk response to immunization and to the production of anti-dsDNA Abs. In vitro experiments revealed that CD4+ T cells with preformed CD40L could, upon stimulation, provide antiapoptotic signals for B cells but could not induce proliferation or reduce activation threshold. These results suggest that the direct target cells for the effect of T cells with preformed CD40L in lupus may not be B lymphocytes.

Synovial fluid cytokines in patients with rheumatoid arthritis or other arthritic lesions.

The synovial fluid (SF) of rheumatoid arthritis (RA) patients contains a mixture of inflammatory mediators. In order to determine whether certain cytokine patterns locally in the joint are specifically related to the chronic inflammation in RA, the concentrations of interleukin (IL)-1alpha, IL-1beta, IL-6, IL-10, transforming growth factor-beta (TGF-beta), tumour necrosis factor-alpha (TNF-alpha) and IgG2b-inducing factor (IgG2bIF) were measured in SF from 22 patients with RA and 22 patients with other types of arthritic lesions. High levels of IL-10, latent and active TGF-beta and the presence of IgG2bIF are significantly correlated with RA when corrected for age. As these factors have the capacity to promote antibody production, they might contribute to the maintenance of local antibody production in RA synovial tissues. All RA-SF samples contained detectable levels of IL-10 and all except one contained IL-1beta, while concentrations in several non-RA-SF samples were below detection limits. IL-6 and TGF-beta were present in all SF samples from both RA and non-RA patients. The presence of IgG2bIF was strongly correlated with high levels of IL-10 and IL-1beta in SF. However, no distinct cytokine profile specific for the chronic inflammation characteristic of RA was found.

Autoantibody patterns in synovial fluids from patients with rheumatoid arthritis or other arthritic lesions.

Patients with rheumatoid arthritis (RA) produce a variety of autoantibodies, not only demonstrable in the circulation, but also locally in the inflamed joint. We investigated the local production of several autoantibodies in the synovial fluid (SF) of 24 patients with RA and of 26 patients with other arthritic lesions. RA patients had higher titres of immunoglobulin M (IgM) and immunoglobulin G (IgG) rheumatoid factors (RFs) and of collagen type II antibodies in SF, whereas there were no demonstrable differences between groups with regard to antibodies against double-stranded (ds) DNA, C1q or the hapten 2,4,6-trinitrobenzene sulfonic acid (TNP). No differences were observed for total synovial levels of IgM or IgG. There was no autoantibody pattern that was typical of RA patients, except for the local presence of RF, primarily in seropositive RA patients. Our findings therefore support the notion that RF and collagen type II antibodies are induced by immunogenic material present in the local inflamed environment. In the accompanying paper we studied various synovial fluid cytokines in the same patient groups. Here we correlated the level of these cytokines with autoantibody titres in SF, but no specific cytokine associated with the production of RF was found. Hence, we conclude that several different inflammatory mediators might contribute to the chronic inflammation and autoantibody production in the joint of RA patients. An inverse correlation was established between concentrations of tumour necrosis factor-alpha (TNF-alpha) and levels of total IgG.

IgG2b inducing factor from rheumatoid arthritis synovial fluid activates antibody production in highly purified mouse B lymphocytes.

Rheumatoid arthritis synovial fluid (RA-SF) contains a factor that induces IgG2b antibody production in LPS-stimulated murine B cells and therefore is called IgG2b inducing factor (IgG2bIF). When LPS, together with crude RA-SF or semi-purified IgG2bIF, was added to highly purified LPS-stimulated B cells, the number of IgG2b-producing cells was substantially enhanced. This shows that IgG2bIF acts directly on activated B cells, presumably by binding to a receptor expressed on LPS-activated B cells. In vivo LPS-activated B blasts were not able to respond to RA-SF unless LPS was present in vitro, showing that LPS is needed to maintain cell viability and responsiveness to the IgG2bIF. To elucidate the mechanism for the IgG2bIF effect on highly purified B cells, the IgG2b response of LPS-stimulated, Bruton's tyrosine kinase-defective, xidB blasts was studied. Purified B blasts from the btk-defective CBA/N mouse strain were sensitive to IgG2bIF. These findings show that IgG2bIF acts directly on B cells and activates cells through a btk-independent pathway.

IgG2b inducing factor from rheumatoid arthritis synovial fluid synergizes with transforming growth factor-beta in promoting IgG2b antibody production in mouse B lymphocytes.

Rheumatoid arthritis synovial fluid (RA-SF) contains a distinct biological activity that selectively induces IgG2b production in LPS-activated murine B blasts. This IgG2b inducing factor (IgG2bIF) acts directly on purified LPS-activated B blasts from normal and Bruton's tyrosine kinase-defective CBA/N mice. In order to test the possibility that TGF-beta and IgG2bIF in RA-SF act in concert to induce IgG2b production, anti-TGF-beta monoclonal antibodies and RA-SF were added to LPS-activated CBA B blasts, which led to a marked reduction of IgG2b-producing cells. This result indicates that TGF-beta and IgG2bIF in RA-SF synergize in the induction of IgG2b production. TGF-beta antibodies do not inhibit IgG2b production in CBA/N B blasts, further substantiating our earlier notion that CBA/N B blasts have a higher endogenous production of TGF-beta after LPS stimulation, which might be responsible for the aberrant reactivity in btk deficient CBA/N mice. RA-SF is able to reconstitute the deficient IgG1 response in LPS- and IL-4-stimulated CBA/N B blasts. Addition of antibodies against TGF-beta had only a marginal effect on the IgG1 response, indicating that the reconstitution is mediated by another factor(s), which is present in RA-SF.

Differential sensitivity to transforming growth factor (TGF)-beta of CBA and of CBA/N B cells demonstrates that the IgG2b inducing factor in synovial fluid from rheumatoid arthritis patients is not identical to TGF-beta.

Synovial fluid from patients with rheumatoid arthritis (RA-SF) contains in vivo produced cytokines and inflammatory mediators, including a factor that induces IgG2b production of lipopolysaccharide (LPS) preactivated murine B lymphocytes. In order to determine the mechanism by which RA-SF acts on LPS activated mouse B cells, CBA/N mice were used as an experimental model. The X-linked immunodeficiency of these mice is caused by a point mutation in the Bruton's tyrosine kinase (btk) gene. We have earlier shown that RA-SF can reconstitute the CBA/N B cell deficiency in vitro and in vivo, with regard to IgG2b production after LPS stimulation. Since transforming growth factor (TGF)-beta has been suggested to be a switch factor for IgG2b, we aimed at investigating the role of TGF-beta in our experimental system. We found that TGF-beta could not mimic the effect of RA-SF on CBA spleen cells. A small increase of IgG2b secretion was observed with spleen cells from normal CBA mice, whereas Ig secretion of all isotypes was suppressed in CBA/N spleen cells treated with TGF-beta at any concentration. Neutralizing antibodies against TGF-beta suppressed the response of CBA B cells, whereas the response by CBA/N B cells was enhanced by the same antibody preparation. Here we also show that the abnormal B cell responsiveness to TGF-beta, typical of CBA/N, co-segregates with the btk mutation in male (CBA x CBA/N)F2 spleen cells. This was determined by allele specific PCR recognizing the identified base substitutions of the btk gene, typical of the two strains. We propose that RA-SF contains a factor, separate from TGF-beta, that is involved in the differentiation of IgG2b expressing cells.

Protein-G binding material from synovial fluid of rheumatoid arthritis patients induces unorthodox autoantibodies (IgG1 rheumatoid factor) in NZB, NZW and (NZB x NZW)F1 mice.

Our previous studies have demonstrated that injection of rheumatoid arthritis (RA) synovial fluid (SF) induces a marked increase mainly of IgG1 antibody-producing cells in autoimmune disease prone (NZB x NZW)F1 mice but not in CBA mice. In the present study, the in vivo effect of RA-SF on autoantibody production was tested in different strains of mice. Injection of RA-SF induced the production of unorthodox autoantibodies (IgG1 rheumatoid factor, RF) in young (NZB x NZW)F1 mice as well as in their parental strains NZB and NZW, but not in normal mice (CBA) or in mice with severe combined immunodeficiency, indicating that the response is not caused by a conventional immune response against RA-SF material. IgG1 RF production was rapidly induced and reached high levels already on day 7 and lasted for more than 90 days. The induction of IgG1 RF was not the result of polyclonal activation, since RA-SF did not stimulate the production of other antibodies, such as autoantibodies against double-stranded DNA, bromelain-treated mouse red blood cells, myosin, transferrin, cytochrome c, thyroglobulin or myoglobin or antibodies reactive with the hapten TNP. To elucidate the identity of the active substance in RA-SF, responsible for IgG1 RF production, bound and unbound material of RA-SF, eluted from a protein-G column was injected into (NZB x NZW)F1 mice. Only the protein-G binding material was active, indicating that the effect is mediated by autoantibodies or immune complexes in the synovial fluid. Further studies demonstrated that identical concentrations of protein obtained from a pool of normal human IgG or SF from seronegative RA and non-RA arthritides patients did not contain the same activity.