Preexisting antigen-specific immune responses are modulated by oral KLH feeding in humans.

Oral tolerance is the antigen-specific inhibition of a systemic immune response after oral antigen uptake and well established in animal models. We recently showed that keyhole limpet hemocyanin (KLH) feeding modulates subsequently induced systemic immune responses in humans as well. In the present study, we investigated whether oral KLH can also modulate preexisting antigen-specific systemic B- and T-cell responses. We induced delayed-type hypersensitivity (DTH) reactions as well as systemic KLH-specific B- and T-cell responses by subcutaneous KLH injections. Subsequent oral KLH administration decreased the small proportion of antigen-specific CD4(+) T cells positive for the cytokine IL-17 at the end of the feeding regimen even further. After reimmunization, there was no difference in DTH reactions and the KLH-specific B-cell responses, but KLH-fed volunteers had an increased proportion of antigen-specific CD4(+) T cells positive for IL-10 and a reduced proportion of antigen-specific CD4(+) T cells positive for the skin-homing receptor cutaneous lymphocyte antigen and IL-2 and IFN-γ. Taken together, oral KLH can modulate a preexisting systemic KLH-specific immune response. These results suggest that feeding antigen may offer therapeutic strategies for the suppression of unwanted immune reactions in humans.

Dendritic cells from human mesenteric lymph nodes in inflammatory and non-inflammatory bowel diseases: subsets and function of plasmacytoid dendritic cells.

Plasmacytoid dendritic cells (pDC) in mesenteric lymph nodes (MLN) may be important regulators of both inflammatory and non-inflammatory mucosal immune responses but human studies are rare. Here we compare pDC from human MLN and peripheral blood (PB) by phenotype and function. MLN from patients with or without inflammatory bowel disease (IBD) undergoing colon surgery and PB from patients with IBD and from controls were used to isolate mononuclear cells. The pDC were analysed by flow cytometry for the expression of CD40, CD80, CD83, CD86, CCR6, CCR7, CX3CR1, CD103 and HLA-DR. Purified pDC from MLN and PB were stimulated with staphylococcus enterotoxin B (SEB), CpG-A, interleukin-3 (IL-3), SEB + IL-3, CpG-A + IL-3 or left unstimulated, and cultured alone or with purified allogeneic CD4(+) CD45RA(+) HLA-DR- T cells. Subsequently, concentrations of IL-1ß, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, IL-17, interferon-α (IFN-α), IFN-γ and tumour necrosis factor-α (TNF-α) in culture supernatants were determined by multiplex bead array. The PB pDC from IBD patients exhibited an activated and matured phenotype whereas MLN pDC and control PB pDC were less activated. CpG-A and CpG-A + IL-3-stimulated MLN pDC secreted less IL-6 and TNF-α compared with PB pDC from controls. Compared with co-cultures of naive CD4 T cells with PB pDC, co-cultures with MLN pDC contained more IL-2, IL-10 and IFN-γ when stimulated with SEB and SEB + IL-3, and less IFN-α when stimulated with CpG-A. MLN pDC differ phenotypically from PB pDC and their pattern of cytokine secretion and may contribute to specific outcomes of mucosal immune reactions.

Impaired peripheral Th1 CD4+ T cell response to Escherichia coli proteins in patients with Crohn's disease and ankylosing spondylitis.

BACKGROUND: To clarify the impact of T cell responses towards enteric antigens for chronic intestinal inflammation, we determined T helper 1 reactivity towards conserved Escherichia coli proteins in patients with Crohn's disease (CD) and healthy individuals and patients with ankylosing spondylitis (AS), who also often show microscopic inflammatory lesions within the gut or even develop overt inflammatory bowel disease. METHODS: We determined the frequency of IFNγ+CD40L+ cells/CD4+ T cells after stimulation of whole blood with pools of E. coli proteins. RESULTS: The E. coli-specific Th1 response was significantly reduced in CD patients and to a lower extent also in AS patients. CONCLUSIONS: E. coli is a target for polyclonal Th1 responses in healthy individuals. The impairment of these responses in CD and AS patients might be due to recruitment of enterobacteria-specific Th1 cells to the gut or might reflect inadequate priming of adaptive immune response.

Modulation of systemic antigen-specific immune responses by oral antigen in humans.

Oral antigen uptake can induce systemic immune responses ranging from tolerance to immunity. However, the underlying mechanisms are poorly understood, especially in humans. Here, keyhole limpet hemocyanin (KLH), a neoantigen which has been used in earlier studies of oral tolerance, was fed in a repeated low-dose and a single high-dose protocol to healthy volunteers. KLH-specific CD4(+) T-cell proliferation and cytokine production, as well as KLH-specific serum Ab and the effects of oral KLH on a subsequent parenterally induced systemic immune response, were analyzed. Repeated low-dose oral KLH alone induced antigen-specific CD4(+) T cells positive predominantly for the gut-homing receptor integrin ß7 and the cytokines IL-2 and TNF-α; some CD4(+) T cells also produced IL-4. Oral feeding of KLH accelerated a subsequent parenterally induced systemic CD4(+) T-cell response. The cytokine pattern of KLH-specific CD4(+) T cells shifted toward more IL-4- and IL-10- and less IFN-γ-, IL-2- and TNF-α-producing cells. The parenterally induced systemic KLH-specific B-cell response was accelerated and amplified by oral KLH. The impact of single high-dose oral KLH on antigen-specific immune responses was less pronounced compared with repeated low-dose oral KLH. These findings suggest that oral antigen can effectively modulate subsequently induced systemic antigen-specific immune responses. Immunomodulation by oral antigen may offer new therapeutic strategies for Th type1-mediated inflammatory diseases and for the development of vaccination strategies.

Significant differences between Crohn's disease and ulcerative colitis regarding the impact of body mass index and initial disease activity on responsiveness to azathioprine: results from a European multicenter study in 1,176 patients.

In a survey comprising 1,176 patients with inflammatory bowel disease (IBD) we recently showed that azathioprine (AZA) beyond 4 years is beneficial in ulcerative colitis (UC) patients and in a subset of Crohn's disease (CD) patients. Here, we show for the first time that azathioprine responsiveness depends on body mass index (BMI). The relationship is reciprocal in UC and CD, with a better outcome in UC patients with a BMI<25 and in CD patients with a BMI>25. These observations are particularly interesting considering the evolving concept of a relationship between fatty metabolism and immune regulation. Additionally, we show that CD patients, but not UC patients, respond better to AZA when it is started in clinical remission. This observation may support data favouring a "hit hard and early" regime in CD. Finally, we were able to demonstrate a decrease in the incidence of CD-related complications requiring surgery through treatment with AZA.

Oral polio vaccination leads to oligoclonal expansion of TCRBV16+ and TCRBV13+ T cells in the colon of rhesus macaques.

In studying immune responses towards the poliovirus, data about T cell mediated immunity in the intestine as the main portal of viral entry in disease and vaccination is lacking. We treated two macaques with oral Polio vaccine and collected duodenal and colonic biopsy specimens. RNA isolation, reverse transcription, and polymerase chain reaction were performed for fragment analysis of the complementarity determining region 3 (CDR3) of the T cell receptor beta chain variable region (TCRBV), followed by subcloning and sequencing of expanded bands. In the colon, oligoclonal expansions of TCRBV16+ or TCRBV13+ intestinal T cells with conserved motifs of the hypervariable CDR3 were found. Flow cytometric analysis of mucosal T cells revealed that activated colonic T cells were mainly CD4(+). Our results indicate that there is a local activation of oligoclonal T cells in the colon after oral Polio vaccination (OPV) which involves selected TCRBV families and may occur within the CD4(+) T cell subset.

Autoregulation of Th1-mediated inflammation by twist1.

The basic helix-loop-helix transcriptional repressor twist1, as an antagonist of nuclear factor kappaB (NF-kappaB)-dependent cytokine expression, is involved in the regulation of inflammation-induced immunopathology. We show that twist1 is expressed by activated T helper (Th) 1 effector memory (EM) cells. Induction of twist1 in Th cells depended on NF-kappaB, nuclear factor of activated T cells (NFAT), and interleukin (IL)-12 signaling via signal transducer and activator of transcription (STAT) 4. Expression of twist1 was transient after T cell receptor engagement, and increased upon repeated stimulation of Th1 cells. Imprinting for enhanced twist1 expression was characteristic of repeatedly restimulated EM Th cells, and thus of the pathogenic memory Th cells characteristic of chronic inflammation. Th lymphocytes from the inflamed joint or gut tissue of patients with rheumatic diseases, Crohn's disease or ulcerative colitis expressed high levels of twist1. Expression of twist1 in Th1 lymphocytes limited the expression of the cytokines interferon-gamma, IL-2, and tumor necrosis factor-alpha, and ameliorated Th1-mediated immunopathology in delayed-type hypersensitivity and antigen-induced arthritis.

Homologous high-throughput expression and purification of highly conserved E coli proteins.

BACKGROUND: Genetic factors and a dysregulated immune response towards commensal bacteria contribute to the pathogenesis of Inflammatory Bowel Disease (IBD). Animal models demonstrated that the normal intestinal flora is crucial for the development of intestinal inflammation. However, due to the complexity of the intestinal flora, it has been difficult to design experiments for detection of proinflammatory bacterial antigen(s) involved in the pathogenesis of the disease. Several studies indicated a potential association of E. coli with IBD. In addition, T cell clones of IBD patients were shown to cross react towards antigens from different enteric bacterial species and thus likely responded to conserved bacterial antigens. We therefore chose highly conserved E. coli proteins as candidate antigens for abnormal T cell responses in IBD and used high-throughput techniques for cloning, expression and purification under native conditions of a set of 271 conserved E. coli proteins for downstream immunologic studies. RESULTS: As a standardized procedure, genes were PCR amplified and cloned into the expression vector pQTEV2 in order to express proteins N-terminally fused to a seven-histidine-tag. Initial small-scale expression and purification under native conditions by metal chelate affinity chromatography indicated that the vast majority of target proteins were purified in high yields. Targets that revealed low yields after purification probably due to weak solubility were shuttled into Gateway (Invitrogen) destination vectors in order to enhance solubility by N-terminal fusion of maltose binding protein (MBP), N-utilizing substance A (NusA), or glutathione S-transferase (GST) to the target protein. In addition, recombinant proteins were treated with polymyxin B coated magnetic beads in order to remove lipopolysaccharide (LPS). Thus, 73% of the targeted proteins could be expressed and purified in large-scale to give soluble proteins in the range of 500 microg. CONCLUSION: Here, we report a cost-efficient procedure to produce around 200 soluble recombinant E. coli proteins in large-scale, including removal of LPS by polymyxin B coated beads for subsequent use of the proteins in downstream immunological studies.

Psychological treatment may reduce the need for healthcare in patients with Crohn's disease.

BACKGROUND: Few published studies examine the influence of psychological treatment on health care utilization in Crohn's disease. METHODS: The present substudy of a prospective, randomized, multicenter trial conducted in 69 of 488 consecutive Crohn's disease (CD) patients was designed to investigate the way in which healthcare utilization is influenced by psychotherapy and relaxation in addition to standardized glucocorticoid therapy. Before and after a 1-year period of standardized somatic treatment the psychotherapy and control groups were compared with regard to hospital and sick-leave days. Predictors of healthcare utilization were analyzed. RESULTS: The comparison between groups before and after psychological treatment showed a significantly higher decrease of mean hospital days (P < 0.03) and sick-leave days in the treatment group compared with the controls. When a covariate analysis was applied to compare the data at randomization, the difference in hospital days remained statistically a trend (P < 0.1). Multivariate regression analysis detected a significant gender and depression effect for hospital days (cor r(2) = 0.114) and a significant gender and age effect for sick-leave days (cor r(2) = 0.112). CONCLUSION: A significant drop in healthcare utilization after psychological treatment demonstrates a clear benefit of this additional therapy. This is important, since the study failed to demonstrate significant changes in the psychosocial status or somatic course of study patients. Clinical and psychological factors influencing these outcomes are discussed.

Pulmonary fibrosis after chemotherapy with oxaliplatin and 5-fluorouracil for colorectal cancer.

BACKGROUND: Chemotherapy with oxaliplatin and 5-fluorouracil (5-FU)/folinic acid is the standard first-line therapy of metastatic colorectal carcinoma and has shown activity in several other malignancies. This regimen is mostly well tolerated. Known side effects include myelosuppression, nausea/vomiting and neuropathies; acute pulmonary toxicity has only been described in very few reports. CASE REPORT: A 66-year-old male with metastatic rectal adenocarcinoma treated with 12 cycles of oxaliplatin and 5-FU/folinic acid developed bilateral pulmonary infiltrates and respiratory failure. Broad-spectrum antibiotic therapy did not improve his condition and extended microbiological diagnostics did not show an infectious etiology. Therapy with corticosteroids led to a short improvement, however the patient died 1 week after the initiation of corticosteroid treatment due to respiratory insufficiency. The clinical and histopathological data as well as the lack of an infectious cause indicate that pulmonary fibrosis was induced by oxaliplatin and 5-FU/folinic acid. CONCLUSION: This case demonstrates that treatment with oxaliplatin and 5-FU/folinic acid can cause acute pulmonary fibrosis. Even though pulmonary toxicity is rare in patients treated with this chemotherapy regimen compared to infectious pulmonary complications, it should be considered early in the clinical course of otherwise unexplained pulmonary infiltrates hopefully leading to a better outcome.

Long-term effectiveness of azathioprine in IBD beyond 4 years: a European multicenter study in 1176 patients.

In Crohn's disease the optimal duration of azathioprine treatment is still controversial and for ulcerative colitis only limited data are available to support its efficacy. Charts of 1176 patients with IBD from 16 European centers were analyzed. Flare incidences and steroid dosages were assessed for the time before and during treatment and after discontinuation. Within the first 4 years, azathioprine suppressed flare incidence and steroid consumption in both diseases (P < 0.001). While in CD discontinuation after 3-4 years did not lead to reactivation, this was the case in UC. However, continuation beyond 4 years further improved clinical activity in CD and steroid requirement in both diseases (P < 0.001). Discontinuation of azathioprine may thus be considered after 3-4 years in CD patients in complete remission without steroid requirement. In all other CD patients and for UC patients in general, continuation seems beneficial. These results support a novel differential algorithm for long-term azathioprine therapy in IBD.

Mucosal but not peripheral FOXP3+ regulatory T cells are highly increased in untreated HIV infection and normalize after suppressive HAART.

Recent evidence indicates that regulatory T cells (T(regs)) play an important role in HIV infection. However, although the gastrointestinal mucosa is a key compartment in HIV disease, no data on mucosal T(regs) in HIV infection are available. In this study, we compared the frequency of T(regs) in duodenal mucosa and peripheral blood (PB) of 13 treatment-naive and 13 suppressively treated HIV-infected patients with that of 6 patients with norovirus infection and 12 healthy controls. T(regs) were quantified by immunohistochemistry (CD3/FOXP3) and further characterized (CD25, CTLA-4, GITR) by immunohistochemistry, immunofluorescence, and fluorescence-activated cell sorting (FACS). Both the frequency and the absolute count of mucosal T(regs) were highly increased in untreated HIV patients but were normal in treated HIV patients. In contrast, in peripheral blood of HIV patients, the absolute number of T(regs) was not increased, and their frequency was only slightly elevated. In norovirus infection, frequency of mucosal T(regs) in the CD4+ T-cell subset was not elevated. The high increase in count and frequency of mucosal T(regs) seems to be a characteristic feature of untreated HIV infection, suggesting a significant contribution of T(regs) to the pathogenesis of HIV disease. Their role may be 2-edged: attenuating HIV-induced immune hyperactivation while suppressing the immune response to HIV and mucosal pathogens.

The role of probiotics and antibiotics in regulating mucosal inflammation.

Antibiotic and probiotic agents have increasingly moved in the focus of basic and clinical research as well as clinical trials for IBD therapy. Both approaches modulate the intestinal flora, the former through eradication or reduction, the latter through establishment or increase of luminal bacteria. Although clinical trials provide proof of principle that both approaches can be therapeutically successfull, we just start to understand the mechanims and may get a first feeling for the potential and limitations of these "microbial" therapies. As basic research sets out to dissect the field using extensive efforts and new technologies, a more detailed exploration of the genetic, immune and microbial factors that govern the life-long crosstalk between host and intestinal flora is already opening new insight into general aspects of human immunology, immune regulation, IBD pathogenesis and therapy.

Mucosal FOXP3+ regulatory T cells are numerically deficient in acute and chronic GvHD.

CD4+CD25+ regulatory T cells (Tregs) control immune responses to self- and foreign antigens and play a pivotal role in autoimmune diseases, infectious and noninfectious inflammation, and graft rejection. Since recent experimental studies have indicated that Tregs were able to ameliorate graft-versus-host disease (GvHD), we analyzed the number of infiltrating Tregs in the intestinal mucosa as one site of GvH reactivity using immunoenzymatic labeling to enumerate FOXP3+ T cells in 95 intestinal biopsies from 49 allografted patients in comparison with healthy controls and patients with infectious inflammation. While patients with cytomegalovirus (CMV)-colitis or diverticulitis showed a concomitant increase of CD8+ effectors and Tregs, acute and chronic GvHD were characterized by the complete lack of a counter-regulation indicated by a FOXP3+/CD8+ T-cell ratio identical to healthy controls. In contrast, specimens without histologic signs of GvHD demonstrated increased numbers of FOXP3+ per CD8+ T cells, indicating that the potential for Treg expansion is principally maintained in allografted patients. Our findings provide evidence that GvHD is associated with an insufficient up-regulation of Tregs in intestinal GvHD lesions. The determination of FOXP3+/CD8+ ratio can be a helpful tool to discriminate GvHD from infectious inflammation after allogeneic stem cell transplantation.

Peripheral and intestinal regulatory CD4+ CD25(high) T cells in inflammatory bowel disease.

BACKGROUND & AIMS: Regulatory CD25+ T cells (T(reg)) are effective in the prevention and down-regulation of inflammatory bowel disease (IBD) in animal models. Functional T(reg) cells are characterized by the expression of the transcription factor FOXP3 and show a CD4+ CD25(high) phenotype in humans. The aim of this study was to determine whether disease activity in IBD correlates with changes in frequency of T(reg) cells and their distribution in the intestinal mucosa. METHODS: T(reg) cells were analyzed from peripheral blood and from biopsy specimens of IBD patients, inflammatory controls, and healthy volunteers by flow cytometry (CD4+ CD25(high)), immunochemistry (FOXP3), and real-time PCR (FOXP3). Regulatory properties of purified peripheral CD4+ CD25(high) T(reg) cells were determined by their suppressive effect on the proliferation of CD4+ CD25- T cells. RESULTS: In peripheral blood, CD4+ CD25(high) T cells from IBD patients retain their suppressive activity. CD4+ CD25(high) and FOXP3+ T(reg) cells are increased during remission but decreased during active disease. This contrasts with their strong increase in peripheral blood of patients with acute diverticulitis. Different than peripheral blood, inflamed IBD mucosa contains an increased number of CD4+ CD25(high) T cells, FOXP3+ T cells, and transcripts for FOXP3 compared with noninflamed mucosa. However, the increase of FOXP3+ T cells in IBD lesions is significantly lower compared with inflammatory controls. CONCLUSIONS: The frequency of CD4+ CD25+ T(reg) cells varies with IBD activity. Active IBD is not associated with a functional defect but with a contraction of the peripheral blood T reg pool and an only moderate expansion in intestinal lesions. Thus, compensatory mechanisms, numerically, are not successfully achieved in these diseases.

[Severe erythrodermic psoriasis in a patient with 22q11 deletion syndrome]. / Schwere psoriatische Erythrodermie bei 22q11-Deletionssyndrom.

BACKGROUND: Erythrodermic psoriasis is a severe manifestation of psoriasis and can be triggered by several factors. CASE REPORT: A 35-year-old man was admitted with severe, almost generalized exfoliative, oozing erythrodermic psoriasis, fever, and cramping of hands and legs. He was under systemic treatment with acitretin. Laboratory examination revealed a marked hypocalcemia as a consequence of primary hypopara thyroidism as well as hypalbuminemia. After normalization of the serum calcium and albumin levels, cutaneous symptoms and fever rapidly improved. No infectious etiology could be found. Hypoparathyroidism together with a right-sided aorta was caused by a 22q11 deletion syndrome. CONCLUSION: Epidermal cell proliferation and formation of intercellular junctional components of the epidermis are strongly calcium-dependent. Furthermore, carriers like albumin are necessary for the transportation of acitretin in the peripheral tissue. This case report suggests that calcium can be involved in psoriasis pathogenesis at least in a subgroup of patients and that systemic retinoids exhibit insufficient effectiveness under low serum albumin levels.

Intestinal flora and mucosal immune responses.

The normal intestinal flora and the mucosal immune system exist in close spatial proximity. A normal structure and function of both very complex systems is required for health and develops in a constant and interactive process. An abnormal host response to the normal intestinal flora leads to chronic intestinal inflammation. Probiotic bacteria may modulate the intestinal flora and the mucosal immune response and are an effective therapy for remission maintenance of ulcerative colitis and pouchitis.

Pancreatic panniculitis in an 88-year-old man with neuroendocrine carcinoma.

Pancreatic panniculitis is a rare complication that occurs in 0.3-3% of patients with pancreatic diseases. Most of the cases reported to date were associated with adenocarcinoma and acute or chronic pancreatitis. We here present an 88-year-old man who was admitted to our institution with a nonfunctional neuroendocrine carcinoma of the pancreas. He subsequently developed pancreatic panniculitis and arthritis. Treatment with octreotide did not have an effect neither on progression of the carcinoma nor on development of new skin lesions. Two months after the diagnosis of pancreatic panniculitis had been made, the patient died from progressing carcinoma. A review of the literature shows that there is no congruent hypothesis for the pathogenesis of pancreatic panniculitis. Vascular damage seems to induce lipolysis by pancreatic enzymes. This eventually leads to fat necrosis. The diversity of disorders that can go along with pancreatic panniculitis suggests an unspecific damage of pancreatic tissue as a first step in the chain of events.