Subnormal activation of phagocytes by complement in chronic inflammatory bowel disease? Neutrophil chemotaxis to complement split product C5a

Genome-wide association study of susceptibility to infection by Mycobacterium avium subspecies paratuberculosis in Holstein cattle

Paratuberculosis, or Johne's disease, is a chronic, granulomatous, gastrointestinal tract disease of cattle and other ruminants caused by the bacterium Mycobacterium avium, subspecies paratuberculosis (MAP). Control of Johne's disease is based on programs of testing and culling animals positive for infection with MAP while concurrently modifying management to reduce the likelihood of infection. The current study is motivated by the hypothesis that genetic variation in host susceptibility to MAP infection can be dissected and quantifiable associations with genetic markers identified. For this purpose, a case-control, genome-wide association study was conducted using US Holstein cattle phenotyped for MAP infection using a serum ELISA and/or fecal culture test. Cases included cows positive for either serum ELISA, fecal culture or both. Controls consisted of animals negative for the serum ELISA test or both serum ELISA and fecal culture when both were available. Controls were matched by herd and proximal birth date with cases. A total of 856 cows (451 cases and 405 controls) were used in initial discovery analyses, and an additional 263 cows (159 cases and 104 controls) from the same herds were used as a validation data set. Data were analyzed in a single marker analysis controlling for relatedness of individuals (GRAMMAR-GC) and also in a Bayesian analysis in which multiple marker effects were estimated simultaneously (GenSel). For the latter, effects of non-overlapping 1 Mb marker windows across the genome were estimated. Results from the two discovery analyses were generally concordant; however, discovery results were generally not well supported in analysis of the validation data set. A combined analysis of discovery and validation data sets provided strongest support for SNPs and 1 Mb windows on chromosomes 1, 2, 6, 7, 17 and 29.

Inflammatory bowel diseases in patients with adaptive and complement immunodeficiency disorders

Crohn's disease and ulcerative colitis are idiopathic chronic inflammatory diseases that primarily affect the gastrointestinal tract. The underlying causes remain poorly understood, but there is a growing body of evidence advocating a likely primary pathogenic role for immunodeficiency in the development of Crohn's lesions. Concordantly, a number of congenital immunodeficiencies disrupting the cellular innate immune system strongly predispose to noninfectious, Crohn's-like inflammatory bowel disease. There are case reports and series suggesting that the same may be true for some of the congenital adaptive and complement immunodeficiencies. This review considers and critiques these potential associations.

Demonstration of circulating immune complexes by the indirect leucocyte phagocytosis test in chronic inflammatory bowel disease. Relation to results of a standard complement consumption assay

Circulating immune complexes were studied in untreated Crohn's disease (CD) and ulcerative colitis (UC) by leucocyte phagocytosis. Neutrophils from normal donors took up large immunoglobulin-containing inclusions from 14 of 15 CD sera, 3 of 15 UC sera (p less than 0.002) and from none of 15 reference sera from healthy volunteers (p less than 0.002). In contrast, inclusions could not be demonstrated on direct microscopic investigation. Our study confirms the presence of circulating immune complexes in Crohn's disease. Predominance of IgG-containing complexes in this condition is consistent with a mucosal origin. Discrepant results obtained by direct examination and by incubation of sera from patients with normal test neutrophils suggest a defective immune complex phagocytosis in CD. In consistency with this possibility, control experiments revealed a markedly decreased complex uptake by neutrophils of CD patients in vitro.

Circulating neutrophils from patients with ulcerative colitis have a normal respiratory burst

The hallmark of ulcerative colitis is a diffuse infiltration of neutrophils from the circulation into the colonic mucosa. The underlying mechanism for neutrophil tissue infiltration is unknown. One possible hypothesis is abnormal circulating neutrophils. This hypothesis has been previously tested with conflicting results. The aim of our study was to re-evaluate circulating neutrophil function in the absence of several possible confounding factors. To this end, we measured the respiratory burst of circulating neutrophils in response to two different stimuli by chemiluminescence in patients with active and inactive ulcerative colitis being off all medications. Our results show no significant difference between ulcerative colitis patients and controls in peak chemiluminescence, area-under-the-curve and time to peak comparisons. However, 27% of patients with active ulcerative colitis had an abnormally elevated chemiluminescence to stimuli. In addition, no correlations were seen between disease activity and peak chemiluminescence. Thus circulating neutrophils in the majority of patients with ulcerative colitis do not appear to be either "primed" or hyperactive. This may suggest the presence of local colonic factors that lead to neutrophil tissue infiltration and activation.

'Conversion' from ulcerative colitis to Crohn's disease associated with corticosteroid treatment

A man who was a non-smoker presented with clinical, histological, and radiological features typical of distal ulcerative colitis. Prolonged treatment with corticosteroids was associated with the development of numerous granulomata, stricturing, and perianal disease. It is speculated that the immunosuppression associated with the corticosteroid treatment may have induced a change from ulcerative colitis to Crohn's disease of the colon. This case report lends support to the hypothesis that these conditions may just represent different forms of a continuum of inflammatory bowel disease.

Respiratory burst of circulating polymorphonuclear leukocytes and plasma elastase levels in patients with inflammatory bowel disease in remission

The activation of circulating polymorphonuclear leukocytes was determined in terms of superoxide radical generation and granulocyte elastase release in untreated patients with ulcerative colitis (N = 10) and Crohn's disease (N = 9) in remission and in control subjects (N = 10). Superoxide radical generation was determined by monitoring spectrophotometrically the reduction of ferricytochrome, after stimulation of cells with phorbol myristate acetate. Plasma elastase concentration was measured by a solid-phase enzyme immunoassay technique as the complex with alpha-1-proteinase inhibitor. Superoxide formation by polymorphonuclear leukocytes from patients with ulcerative colitis and Crohn's disease was significantly lower compared with controls [median (range) nmol/min/mg protein: Crohn's disease 7.8 (7.1-9.6); ulcerative colitis 8.25 (7.4-10.3); controls 14.7 (13.6-15.8)] (P < 0.001), while no difference was found between the two groups of patients. In contrast plasma elastase levels in patients with ulcerative colitis and Crohn's disease were similar to that of controls. This defective respiratory burst of polymorphonuclear leukocytes in patients with inflammatory bowel disease in remission, in absence of an altered degranulation, could represent an important factor for the pathogenesis of these diseases.

Reassessment of two Boyden chamber methods for measuring canine neutrophil migration: the leading front and the lower surface count assays

Laboratory investigation of neutrophil locomotion has attracted a great deal of attention owing to its potential usefulness to veterinary clinical medicine. Two of the most important principles for measurement of chemotaxis are the leading front and lower surface count techniques. The latter assay has become increasingly popular following the introduction of multi-well chambers utilizing polycarbonate filters. In the present study, this method was compared quantitatively and qualitatively to the leading front assay. Further, the potential usefulness of a simple shape-change assay as a rapid measure of chemotactic activation of neutrophils was assessed and compared with the migration assays. It was concluded that the two migration assays are superior to the shape-change assay, even though both suffer from certain methodological drawbacks. This may be relevant to the elucidation of clinical cases of neutrophil dysfunction.

Serum interferon activity in inflammatory bowel disease. Arachidonic acid release and lipoxygenation activated by alpha-class interferon in human neutrophils

Serum interferon (IFN) of alpha-class was studied in 64 consecutive patients, 26 with Crohn's disease, 38 with ulcerative colitis, and in 34 healthy volunteers. Detectable IFN-alpha in 10 patients was associated with a moderate to severe activity of chronic inflammatory bowel disease (CIBD). However, 19 of 28 patients (68%) with activity in their disease did not have elevated IFN-alpha levels. The three groups, ulcerative colitis, Crohn's disease, and healthy volunteers did not reveal any statistically significant difference in serum IFN-alpha, as four of 34 healthy controls without intercurrent infections had elevated levels as well. Possible effects of alpha, beta, and gamma classes of IFN on endogenous arachidonic acid (AA) release and metabolism in human neutrophils was investigated in a substudy. IFN-alpha caused a dose-dependent release of AA from phospholipids and metabolism of a modest fraction of leukotriene B4 (LTB4) and 5-hydroxyeicosatetraenoic acid (5-HETE) at doses reaching a maximum of 100 IU/ml. IFN of the beta and gamma classes did not exert such effects. Addition of complement 5a to cells activated by IFN-alpha caused induction of increased 5-lipoxygenase activity with unchanged release of AA. As only 16% of all CIBD patients had elevated IFN-alpha levels as compared to 12% among the group of healthy volunteers, IFN-alpha does not seem to be of importance for the perpetuation of the inflammatory reaction in ulcerative colitis or Crohn's disease, and other factors may therefore be responsible for activation of the inflammatory cells to production of LTB4 and 5-HETE.

Diminished neutrophil function in Crohn's disease and ulcerative colitis identified by decreased oxidative metabolism and low superoxide dismutase content

Features of the neutrophil oxidative metabolism and enzyme activity in peripheral blood neutrophils were studied in 43 patients with Crohn's disease, 13 with ulcerative colitis and 33 healthy controls. The production of superoxide anion (O2-.) by phorbol-myristate-acetate stimulated neutrophils from patients with Crohn's disease and ulcerative colitis was significantly diminished compared with controls mean (SE) = 47.1 (3.6) and 38.0 (3.8) v 67.4 (7.5) nmol/10(7) cells/min, p less than or equal to 0.02, respectively, while the production of hydrogen peroxide was normal. The neutrophil content of superoxide dismutase (SOD), a cytoprotective enzyme, was also markedly diminished in Crohn's disease mean (SE) = 7.11 (0.23) ng SOD/micrograms DNA, p less than 0.05, and ulcerative colitis mean (SE) = 5.74 (0.42) compared with controls 7.84 (0.27), p less than 0.001. In contrast, the concentration of neutrophil elastase, a neutral protease, was found to be normal when compared with neutrophils from controls. The neutrophil O2-. production and the SOD concentrations were significantly and negatively correlated with the disease activity in Crohn's disease and ulcerative colitis. The results indicate diminished neutrophil function in peripheral blood of patients with Crohn's disease and ulcerative colitis as illustrated by a diminished oxidative system, which correlates with the disease activity.

Activation of neutrophil chemotaxis by leukotriene B4 and 5-hydroxyeicosatetraenoic acid in chronic inflammatory bowel disease

Circulating neutrophils were investigated in 15 patients with Crohn's disease (CD), 15 with ulcerative colitis (UC), and 15 healthy volunteers. Dose-response curves for chemotaxis in Boyden chambers were analysed for sensitivity to leukotriene B4 (LTB4), its 20-hydroxy-LTB4 (20-OH-LTB4) and 20-carboxy-LTB4 (20-COOH-LTB4) catabolites, and 5- and 15-hydroxyeicosatetraenoic acids (HETEs). Positive controls included: complement 5a (C5a), formy-L-methionyl-L-leucyl-L-phenylalanine (f-Met-Leu-Phe), and casein. Control chemotaxis test were performed at concentrations yielding optimal responses in leucocytes of healthy volunteers. Chemotaxis to suboptimal concentrations of LTB4 1.0 and 3.2 nmol/l, and 5-HETE 316 nmol/l, was markedly depressed in patients with chronic inflammatory bowel disease (CIBD). Analyses of individual dose-response curves revealed an underlying decreased sensitivity to LTB4 in 11 out of 30 patients, to 5-HETE in 10 out of 30 patients with a corresponding decrease of median sensitivity to LTB4 and 5-HETE in both CD and UC. Peak responses to LTB4, 5-HETE, f-Met-Leu-Phe, and casein were identical in the three groups tested, whereas the C5a values were significantly depressed in both groups of patients (p less than 0.05). The potency of LTB4 exceeded that of 5-HETE by a factor of approximately 100 whereas 20-OH-LTB4 was nearly as potent as LTB4. 20-COOH-LTB4 and 15-HETE did not activate chemotaxis of human neutrophils. These findings are suggestive of a competitive inhibition of receptors with heterogeneity for LTB4 and 5-HETE.(ABSTRACT TRUNCATED AT 250 WORDS)

Impaired activation of the neutrophil oxidative metabolism in chronic inflammatory bowel disease

The oxidative metabolism of circulating neutrophils was studied in patients with Crohn's disease and ulcerative colitis. The production of superoxide anion (02-.) in patients with ulcerative colitis was markedly decreased irrespective of whether soluble or particulate, non-chemotactic or chemotactic stimuli were used. Crohn's disease neutrophils showed a just marginally diminished 02-. production. Disease activity, as defined by the Crohn's disease activity index, was negatively correlated with the neutrophil O2-. production in both diseases. In both Crohn's disease and in ulcerative colitis neutrophil hydrogen peroxide (H2O2) production was normal. It is concluded that the neutrophil function, as-assessed by superoxide anion production, is impaired in patients with inflammatory bowel disease. It is therefore suggested that the suboptimal microbicidal function of these cells, as demonstrated in the present study, may contribute to the disease process.

Impaired neutrophil function in intestinal lymphangiectasia

Impaired neutrophil chemotaxis and phagocytosis were shown in three patients with intestinal lymphangiectasia. Abnormalities in cell associated and serum derived activity occurred, and possible mechanisms are suggested.

Function of exudative neutrophilic granulocytes in patients with Crohn's disease or ulcerative colitis

Chemotactic, phagocytic, and oxidative metabolic activity of exudative leukocytes was measured in patients with Crohn's disease (n = 20) and with ulcerative colitis (n = 20). Unstimulated and casein-stimulated migration in Boyden chambers did not differ from that of healthy controls (n = 21). Patients with Crohn's disease had reduced serum-independent phagocytosis compared with healthy controls (p less than 0.01) and patients with ulcerative colitis (p less than 0.01). Serum-dependent phagocytosis by leukocytes from patients with Crohn's disease did not differ from that in controls but was slightly increased in patients with ulcerative colitis (p less than 0.02). Unstimulated leukocytes showed increased oxidative metabolic activity in both patient groups compared with controls (p less than 0.01), which was negatively correlated with the disease activity in Crohn's disease (p less than 0.02). The study shows that mobilized leukocytes from patients with Crohn's disease differ from those mobilized in ulcerative colitis and supports the concept of an abnormal inflammatory reaction in Crohn's disease.

Defective modulation of complement in Crohn's disease. C3b opsonization of zymosan by the alternative pathway

Opsonization of zymosan by plasma complement was studied in 12 consecutive patients with untreated, well-established Crohn's disease and in 12 healthy volunteers. Binding of C3b to zymosan was markedly increased in patients with Crohn's disease during the first 30 min of the alternative pathway reaction, whereas consumption of the native C3 protein was within the normal range in all patients. Our results are consistent with a decreased capacity for degradation of activated C3,C3b by the I-H factor inactivator system. This immunologic abnormality may contribute to a chronic activation of the complement sequence, previously demonstrated in Crohn's disease, and to a release of split products of inflammation-promoting character.

Subnormal sensitivity of neutrophils to complement split product C5a in rheumatoid arthritis: relation to complement catabolism and disease extent

The capacity of circulating neutrophils for activation by complement was studied in outpatients with classical or definite rheumatoid arthritis during treatment with dextropropoxyphene only. Analysis of dose-response in the Boyden chamber assay of chemotaxis showed that sensitivity to the potent, complement derived anaphylatoxin, C5a, was markedly decreased, especially in those patients with few joints involved. In contrast, peak response to C5a was within the normal range. Increased complement 3c split products in plasma of the patients suggested involvement of complement cascade reactions. Subnormal sensitivity of neutrophils to phlogistic mediators released by complement may tend to limit their recruitment and potentially tissue destroying secretion locally in rheumatoid arthritis.

Neutrophil recruitment in skin window chambers--activation by complement

Complement was studied in skin window chambers, a human model of neutrophil recruitment in acute aseptic inflammation. Autologous plasma activated by the alternative pathway served as attractant; control chambers were filled with a balanced salt solution or with non-activated plasma samples. Neutrophil accumulation during a 24-hour period was consistently enhanced by activated complement in all of 15 healthy volunteers. Control chambers showed negligible cell counts. Reference assays revealed 1) consumption of the centrally placed complement component, C3, 2) generation of chemotactic activity as assessed in Boyden chambers by the standard complement activation procedure. Simultaneously obtained responses to activated complement in skin window chambers and in the Boyden assay of chemotaxis showed a highly significant, positive correlation. Our results demonstrate that the biological capacity of complement includes stimulation of neutrophil migration during simulated in vivo conditions and thus extends previous observations in animals.

Familial occurrence of complement dysfunction in Crohn's disease: correlation with intestinal symptoms and hypercatabolism of complement

Complement was studied in Crohn's disease probands with early onset and in their first degree relatives. Controls included 24 healthy volunteers and 24 patients with ulcerative colitis or peptic ulcers. Subnormal generation of chemotactic activity by the alternative pathway was shown in eight of 21 probands and in six of 33 relatives, a frequency in both groups significantly different from controls (p less than 0.005), with a strong connection between findings in patients and relatives. As previously shown in patients with Crohn's disease, the subnormal generation was related to decreased utilisation of complement C3 in relatives. Raised levels of circulating complement C3c split products suggested complement involvement in Crohn's disease probands. In contrast, plasma C3c was normal in all relatives, and none of the six cases with complement dysfunction had gastrointestinal symptoms or a history of inflammatory bowel disease. Our data suggest, that complement abnormality seen in Crohn's disease patients does not simply reflect mucosal inflammation or hypercatabolism of complement.