Potent and selective inhibition of in vitro lymphocyte migration by cyclosporine and dexamethasone

Heat stress upregulation of Toll-like receptors 2/4 and acute inflammatory cytokines in peripheral blood mononuclear cell (PBMC) of Bama miniature pigs: an in vivo and in vitro study

Global warming is a challenge to animal health, because of increased heat stress, with subsequent induction of immunosuppression and increased susceptibility to disease. Toll-like receptors (TLR) are pattern recognition receptors that act as sentinels of pathogen invasion and tissue damage. Ligation of TLRs results in a signaling cascade and production of inflammatory cytokines, which eradicate pathogens and maintain the health of the host. We hypothesized that the TLR signaling pathway plays a role in immunosuppression in heat-stressed pigs. We explored the changes in the expression of TLR2, TLR4 and the concentration of acute inflammatory cytokines, such as IL-2, IL-8, IL-12 and IFN-γ in Bama miniature pigs subjected to 21 consecutive days of heat stress, both in vitro and in vivo models. The results showed that heat stress induced the upregulation of cortisol in the plasma of pigs (P<0.05); TLR4 mRNA was elevated, but IL-2 was reduced in peripheral blood mononuclear cells (PBMC, P<0.05). The white blood cell count and the percentage of granulocytes (eosinophilic+basophilic) decreased significantly in heat-stressed pigs (P<0.05). In the in vitro model (PBMC heat shocked for 1 h followed by a 9 h recovery period), TLR2 and TLR4 mRNA expression also increased, as did the concentration of IL-12 in supernatants. However, IFN-γ was significantly reduced in PBMC culture supernatants (P<0.05). We concluded that a consecutive heat stress period elevated the expression of TLR2 and TLR4 in PBMC and increased the plasma levels of inflammatory cytokines. These data indicate that TLR activation and dysregulation of cytokine expression in response to prolonged heat stress may be associated with immunosuppression and increased susceptibility to antigenic challenge in Bama miniature pigs.

Clinical, hematological and biochemical parameters of dairy cows experimentally infected with Vaccinia virus

Vaccinia virus (VACV) is the etiological agent of bovine vaccinia (BV), an important zoonosis that affects dairy cattle. There are many aspects of the disease that remain unknown, and aiming to answer some of these questions, the clinical, hematological, and biochemical parameters of VACV experimentally infected cows were evaluated. In the first part of the study, lactating cows were infected with VACV-GP2 strain. In the second part, animals previously infected with VACV-GP2 were divided into two treatment groups: Group 1, immunosuppressed cows; and Group 2, re-infected cows. In this study, BV could be experimentally reproduced, with similar lesions as observed in natural infections. Moreover, a short incubation period and local lymphadenopathy were also observed. VACV could be detected by PCR and isolated from scabs taken from teat lesions of all inoculated and re-inoculated animals. Lymphocytosis and neutrophilia were observed in all animals from the first part of the experiment, and lymphopenia and relative neutrophilia were observed in the immunosuppressed animals. Detection of viral DNA in oral mucosa lesions suggests that viral reactivation might occur in immunosuppressed animals. Moreover, clinical disease with teat lesions may occur in previously VACV-infected cows under the experimental conditions of the present study.

Treatment of inflammatory bowel disease with corticosteroids

Corticosteroids are a mainstay in the treatment of inflammatory bowel disease. Administered topically, orally, or intravenously corticosteroids rapidly and consistently improve moderate to severe active ulcerative colitis and Crohn's disease, although they are ineffective in the maintenance of remission in either illness. The beneficial effects of corticosteroid therapy are counterbalanced by their many side effects. A better understanding of the mechanism of steroid action and toxicity has led to the development of novel corticosteroids that offer the promise of continued efficacy with minimal toxicity. This article reviews the role of conventional and novel corticosteroids in the management of inflammatory bowel disease.

The role of interleukins 1, 6 and 8 as lymphocyte attractants in the photodermatoses polymorphic light eruption and chronic actinic dermatitis

The two photodermatoses, polymorphic light eruption (PLE) and chronic actinic dermatitis (CAD), are characterized by lymphocyte-rich inflammatory infiltrates, the pathogeneses of which are not fully understood. We have therefore studied suction blister fluid (SBF) samples from patients with these conditions before and at two time points after the induction of experimental lesions by means of a solar simulator; this SBF was then tested for the presence of selected cytokines known to induce peripheral blood lymphocyte (PBL) migration in vitro. A specific EL-4 NOB-1 bioassay was used to detect interleukin (IL)-1 activity, which has already been noted in normal skin and this was found in pre-irradiation control samples as well as 1-3 h and 24 h post-irradiation in both patient groups, but at levels not significantly different from those of controls. Use of a B9 cell proliferation assay showed no detectable IL-6-like activity pre-irradiation, but there was substantial activity in samples at both post-irradiation time points in both patient groups. Further, in other experiments, retained SBF samples were tested in an in vitro PBL migration assay in the presence and absence of neutralizing antibodies against IL-1 alpha, IL-1 beta, IL-6 and IL-8; considerable PBL attractant activity was noted in the pre-irradiation SBF from both patient groups; a finding consistent with previous reports of such activity in samples from normal skin, and at least in CAD patients, a proportion of this activity appeared to be due to IL-1, pre-incubation of SBF with neutralizing antibodies against IL-1 alpha and IL-1 beta reducing the effect significantly. Substantial PBL attractant activity was present also in the SBF from 1-3 h and 24 h post-irradiation samples in both patient groups and again, IL-1 neutralizing antibodies reduced this in the 1-3 h and 24 h CAD samples. In addition, neutralizing antibodies against IL-6 and IL-8 reduced the activity in the 24 h PLE samples significantly and although not fully conclusive in the case of IL-1, these data suggest that IL-6, IL-8 and possibly IL-1 may be involved in the induction of PBL infiltrates, and perhaps other events, in both PLE and CAD.

Clinical applications of technetium Tc 99m hexamethyl propylene amine oxime leukocyte scan in children with inflammatory bowel disease

BACKGROUND

Labeled leukocyte imaging is a helpful diagnostic tool in the detection of inflammation and sepsis. The technetium Tc 99m hexamethyl propylene amine oxime (99mTc HMPAO)-labeled leukocyte scan has been found to be more sensitive than the Indium-111 labeled leukocyte scan in detecting inflammatory bowel disease, with reported sensitivities of 95% to 100%. Experience with the 99mTc HMPAO-labeled leukocyte scan was examined and its clinical applications evaluated in the immediate treatment of patients with inflammatory bowel disease.

METHODS

A retrospective chart review was undertaken that included pediatric patients who underwent 99mTc HMPAO-labeled leukocyte scan at the James Whitcomb Riley Hospital for Children. The disease activity of patients with inflammatory bowel disease was assessed. The leukocyte scan was performed according to the manufacturer's specifications, and images were obtained 30 minutes and 2 hours after administration of the radiopharmaceutical.

RESULTS

During the period of July 1996 through November 1997, 41 scans were performed in 35 patients. Twenty-nine patients had histologically proven inflammatory bowel disease: 24 with Crohn's disease, 4 with ulcerative colitis, and 1 with indeterminate colitis. Active inflammatory bowel disease was suspected in 24 patients when the leukocyte scan was performed. Twenty of the 24 patients (83% sensitivity) had abnormal findings in leukocyte scans that prompted more aggressive management in 15 (75%). Six of the 15 who were receiving maximum medical therapy underwent surgical resection of severely affected bowel segments, and medical treatment was intensified in the other 9. The remaining 5 patients were receiving optimal medical therapy, instituted at their recent visit, and did not require further medication adjustments. Four of the 24 patients with active inflammatory bowel disease had normal leukocyte scans (17% false-negative rate), 3 of whom were receiving corticosteroid therapy at the time the scans were performed. All of the 11 patients in whom inflammatory bowel disease was in remission and 6 patients who did not have inflammatory bowel disease had normal findings in leukocyte scans (100% specificity).

CONCLUSIONS

Although a tissue diagnosis is still recommended, obtained during upper and lower gastrointestinal endoscopic examinations, and contrast radiography of the small bowel for the initial work-up of patients with suspected inflammatory bowel disease, the 99mTc HMPAO-labeled leukocyte scan is a safe and useful diagnostic adjunct for subsequent evaluation of patients known to have inflammatory bowel disease. The results of 99mTc HMPAO-labeled leukocyte scans directly influenced treatment of 75% of the study patients with active inflammatory bowel disease, which included the decision to refer patients for surgical intervention.

Relative sensitivity of Tc-99m WBC versus In-111 WBC in a patient with Crohn disease and steroid use

Numerous studies have shown that chemotaxis is affected by certain antibiotics and steroids. The authors present the case of a patient with Crohn disease relapse with multiple small-bowel fistulae and mesenteric abscesses. Whereas the Tc-99m WBC scan failed to show the intra-abdominal inflammatory foci, an In-111 WBC scan performed within a week delineated the abscesses very well, and these were later confirmed at surgery. This case is presented not only to illustrate the relative sensitivities of a Tc-99m WBC versus an In-111 WBC scan, but also to discuss the impediment to polymorphonuclear chemotaxis by steroids, which may be a contributory factor to the sensitivities of the different radiopharmaceuticals selected for detection of intra-abdominal septic foci.

Relative sensitivity of Tc-99m WBC versus In-111 WBC in a patient with Crohn's disease on steroids

Numerous studies have shown that chemotaxis is affected by certain antibiotics and steroids. A patient had Crohn's disease in relapse with multiple small bowel fistulae and mesenteric abscesses. Although the Tc-99m WBC scan did not show the intra-abdominal inflammatory foci, an In-111 WBC scan performed within a week delineated the abscesses and these were later confirmed at surgery. This case is being presented not only to show the relative sensitivities of a Tc-99m WBC vs. an In-111 WBC scan, but also to discuss the impediment to polymorphonuclear leukocyte chemotaxis by steroids, which may be a contributory factor to the sensitivities of the different radiopharmaceuticals selected for detection of intra-abdominal septic foci.

Cytokines induce lymphocyte migration in vitro by direct, receptor-specific mechanisms

Several cytokines have been found to induce human peripheral blood lymphocyte (PBL) migration in vitro. The mechanisms involved are unclear, therefore experiments were carried out to determine whether PBL migration in response to selected cytokines is due to a direct effect, or to the generation of nonspecific secondary mediators, and whether migration is receptor specific. Purified human PBL were incubated with the lymphocyte chemotactic cytokines interleukin (IL)-1 alpha and IL-8, followed after 30-60 min by addition of specific neutralizing monoclonal antibody. Supernatants of these mixtures were shown by subsequent assay to be devoid of PBL attractant activity, whereas positive control supernatants containing no antibody induced dilution-related migration. Addition of antibody to the high affinity IL-2 receptor abolished the potent attractant effect of IL-2 on PBL, but had little effect on responses to IL-1 alpha and IL-8. These results demonstrate that the in vitro locomotor responses of human PBL to selected cytokines are due to direct, receptor-specific effects and are not dependent upon the generation of secondary mediator(s).

Characterisation of the in vitro responsiveness of lymphocyte subsets to locomotor stimuli by immunocytochemical methods

The in vitro locomotion of lymphocyte subsets has previously been determined by use of highly purified cell populations. A method is now described in which mixed peripheral blood lymphocytes (PBL) migrate to the undersurface of polycarbonate filters in a 48 well microassay, the responding cells being characterised by alkaline phosphatase-anti-alkaline phosphatase immunocytochemistry. Recombinant interleukin (rIL)-1 alpha, zymosan activated plasma (ZAP) and rIL-8 were shown to induce concentration-related migration of mixed PBL in the 48 well assay and were therefore used as reference agonists. Total T cells, B cells, T helper/inducer and T suppressor/cytotoxic cells, as well as lymphocytes stained with the monoclonal antibodies UCHL1 and SN130, have now been quantified after migration to the undersurface of 8 microns pore size polycarbonate filters, in response to optimal concentrations of rIL-1 alpha, ZAP and rIL-8. The value of the analytical method was demonstrated by the selective responses seen. rIL-1 alpha selectively stimulated the migration of T helper/inducer and a small number of B cells without affecting T suppressor/cytotoxic cell locomotion. ZAP and rIL-8 significantly stimulated the migration of T helper/inducer, T suppressor/cytotoxic and B cells. ZAP and rIL-1 alpha also stimulated the migration of both UCHL1 and SN130 positively stained cells. This method may therefore be used to investigate the selective actions of lymphocyte locomotor stimuli on PBL sub-populations without the need to purify specific cell subsets, and to study the specificity of certain inhibitors or drugs on lymphocyte responses.