Martin Hildebrandt

Role of Stress in Functional Gastrointestinal Disorders

Psychological stress is widely believed to play a major role in functional gastrointestinal (GI) disorders, especially irritable bowel syndrome (IBS), by precipitating exacerbation of symptoms. The available data clearly demonstrate that inhibition of gastric emptying and stimulation of colonic transit is the most consistent pattern in the motility response of the GI tract to acute or short-term stress. Thus, one might propose that these alterations might play a pathophysiological role in dyspeptic symptoms and alterations in stool frequency and consistency in patients with stress-related functional GI disorders. Taken together, the above-mentioned studies suggest that the colonic motor response to stress is exaggerated in IBS. There is evidence that an increased emotional response is associated with this difference in colonic, and perhaps also gastric motor responses to certain stressors. However, almost no valid data are available so far from human studies addressing the question if differences in motility responses to stress between patients with functional GI disorders and healthy subjects are due to an altered stress response associated with an imbalance of the autonomic nervous system or increased stress susceptibility. We can summarize that in experimental animals the most consistent pattern of GI motor alterations induced by various psychological and physical stressors is that of delaying gastric emptying and accelerating colonic transit. Endogenous corticotropin-releasing factor (CRF) in the brain plays a significant role in the central nervous system mediation of stress-induced inhibition of upper GI and stimulation of lower GI motor function through activation of brain CRF receptors. The inhibition of gastric emptying by CRF may be mediated by interaction with the CRF-2 receptor, while CRF-1 receptors are involved in the colonic and anxiogenic responses to stress. Endogenous serotonin, peripherally released in response to stress, seems to be involved in stress- and central CRF-induced stimulation of colonic motility by acting on 5HT-3 receptors. Taken together, the limited data available from investigations in healthy subjects and patients with functional GI disorders provide some evidence that stress affects visceral sensitivity in humans. Acute psychological stress seems to facilitate increased sensitivity to experimental visceral stimuli, if the stressor induces a significant emotional change. In summary, studies in experimental animals suggest that stress-induced visceral hypersensitivity is centrally mediated by endogenous CRF and involvement of structures of the emotional motor system, e.g. the amygdala. Stress-induced activation or sensitization of mucosal mast cells in the GI tract seem to be involved in stress-associated alterations of visceral sensitivity.

Murine stress-triggered abortion is mediated by increase of CD8+ TNF-α+ decidual cells via substance P

PROBLEM: Stress is known to induce abortions in mice and humans. Increased levels of abortogenic type 1 helper T‐cell cytokines and decreased levels of pregnancy protective cytokines could be linked to stress‐triggered embryonic loss. Stress promotes neurotransmitter substance P (SP) release in tissues. SP increases the production of decidual tumor necrosis factor (TNF)‐α, whereby the phenotype of these TNF‐α‐producing cells is hypothetical. The objective of the present study was to identify decidual TNF‐α‐producing cell populations that are involved in stress‐induced murine abortion. 
 METHOD: DBA/2J‐mated CBA/J female mice were exposed to ultrasonic sound stress on day 5.5 of pregnancy. The mice were randomized and half were treated with the SP NK1‐receptor antagonist (SP‐RA) RP 67580 (200 μg/mouse). Frequency and cytokine profile of CD8+ cells were evaluated by immunohistochemistry and flow cytometry. Degranulation of uterine mast cells was examined histologically.
 RESULTS: On day 13.5 of pregnancy, the uteri were removed and the resorption rate was calculated. A mean resorption rate of 38.4% was detected in stressed mice (n=10) compared to 13.1% in non‐stressed control mice (n=11, P<0.01). Injection of SP‐RA decreased the abortion rate to 18.4% in stressed mice (n=19, P<0.01). Flow cytometry revealed a stress‐related increase of TNF‐α+/CD8+ decidual T cells, which could be abrogated by SP‐RA (P<0.05). No significant differences could be observed in numbers of mast cells and total CD8+ cells in situ.
 CONCLUSION: Our data suggest that stress‐triggered abortion is mediated by SP, and SP receptor blockade abrogates stress‐triggered abortion via reduced production of TNF‐α by CD8+ T cells.

Simultaneous genotyping of human platelet antigens (HPA) 1 through 6 using new sequence-specific primers for HPA-5

BACKGROUND: Polymerase chain reaction using sequence‐specific primers is widely used for genotyping human platelet antigens (HPA). However, the results of HPA‐5 genotyping are still problematic.

Psychosocial stress of living donors after living donor liver transplantation.

LIVING DONOR liver transplantation (LDLT) has emerged as an established treatment modality in the therapy of terminal liver disease in adults. Surgery-related complications and reports of fatalities among donors result in an ethical dilemma in the process of donor-recipient evaluation. Because the mortality rate among LDLT recipients is low, the surgery-related potential hazard primarily exists for donors. Initial results have shown an overall good psychosocial outcome for donors: all donors reported a willingness to donate on another occasion and no limitations of physical or social activities as of psychologic status. Little is known, however, about the factors that impinge on the psychosocial outcome following organ donation. For this reason, we evaluated the relationship between complications following LDLT surgery and stress perception among donors, and sought potential pre-surgery predictors of enhanced stress perception.

T-cell immune parameters and depression in patients with Crohn's Disease

Goals The causes of Crohns disease (CD) are still considered to be unknown. It is likely that an immune defect leads to an increase in T helper 1 (Th1) cytokine responses, which may then contribute to the characteristic morphologic changes. Increased values in distinct immune activation parameters connected with a Th1 immune response have also been found in patients who are depressed. Because various clinical observations have asserted that a depressive disposition may have some connection with the development of CD, we examined whether a relationship exists between T-cell activation parameters and depressive personality characteristics in patients with CD. Study Seventy-one patients (62% women; age, 38 ± 13 years) with CD (23 with CD Activity Index [CDAI] >150 and 48 with CDAI ≤150) were included in this study. Sixty patients were re-examined after 4.4 ± 1.8 months. The T cell parameters CD2, CD3, CD26, CD28, and CD95 and the activity of dipeptidyl peptidase IV (DPP IV) in serum were examined in the peripheral blood. The patients subjective health status was assessed by means of a standardized psychometric instrument (Short-form Inflammatory Bowel Disease Questionnaire [SIBDQ]). The presence of various characteristics indicative of a depressed mood was also assessed (Center of Epidemiological Studies-Depression Scale, Berliner Stimmungsfragebogen), as well as indicators of a personality disposed to depression (Giessentest) and a depressive illness coping strategy (Freiburger Krankheitsverarbeitungs-Fragebogen), all using the above-mentioned standardized instruments. Results The immune parameters connected with the activation of Th1 (CD25+, CD25+/CD26+) are increased in patients, depending on the stage of illness. In addition, DPP IV activity was significantly lower in patients with an active disease, as was their subjective health status (SIBDQ). A connection with an indicator of mental depression could not be found. Conclusion The observed changes in immune parameters support the idea that morphologic changes could be connected with an increased Th1 response and that DPP IV activity could play an immunomodulatory role. A relationship between the measured immune parameters and individual characteristics of depression could not be found.

Immunomagnetic selection of CD34+ cells: factors influencing component purity and yield

BACKGROUND: In immunomagnetic selection of CD34+ cells from HPC transplants, not all factors that affect yield and purity of CD34+ cells are known.

Pregnancy as a Model of Controlled Invasion Might Be Attributed to the Ratio of CD3/CD8 to CD56

PROBLEM: Pregnancy can be considered as a model of successfully controlled tissue invasion. Cellular mediated immunity appears to regulate the controlled invasion of fetal trophoblast cells. In endometrium cancer, a dysregulation of invasive malignant cells can be observed. Since immuncompetent cells are known to be involved in recognition and rejection of ‘non‐self’ antigens, we investigated the presence and distribution pattern of CD3, CD8, CD56, and CD68 positive cells in decidua from normal and failing pregancies, compared with malignant and benign endometrium.
 METHOD OF STUDY: Decidual tissue from first trimester normal pregancies (NP; n=15) and abortion (AB; n=12), endometrial samples from premenopausal women (NE; n=8), and endometrioid adenocarcinoma (EA; n=8) were examined by immunohistochemistry using monoclonal antibody against large spectrum cytokeratin, and against the receptors CD3, CD8, CD56 and CD68, respectively.
 RESULTS: In NP, we observed 32.5% CD3, 44.7% CD56, and 22.9% CD68+ cells. In AB, we found 36.9% CD3, 45.3% CD56, and 17.8% CD68+ cells. The differences in ratio between normal pregnancy and abortion were not statistically significant. In NE, we counted 39.5% CD3, 30.2% CD56 and 30.2% CD68+ cells. In EA, we observed 47.9% CD3, 12.4% CD56 and 39.7% CD68+ cells. The decrease of CD56 positive cells in endometrioid adenocarcinoma was statistically significant. Interestingly, we found 4.1% of cells positive for CD8 in NP, 4.9% in AB, 22.7% in NE, and 48.2% in EA.
 CONCLUSIONS: The increase of CD8 cells in NE, and particularely in EA, and decrease of CD56 cells, compared with NP or AB, suggests an interaction between CD8 cells and CD56 cells. Studying different pathological situations in the uterus, such as malignancies or ectopic pregnancies, might help us to understand the mechanisms involved in the maintenance of pregnancy.

Dipeptidyl Peptidase IV (DPP IV, CD26) In Patients With Mental Eating Disorders

The notion that patients with eating disorders maintain a functional immunosurveillance in spite of severe malnutrition has attracted researchers for years. Dipeptidyl Peptidase IV (DPP IV), a serine protease with broad tissue distribution and known activity in serum, operates in the cascade of immune responses. Membrane-bound DPP IV expressed on lymphocytes, also known as the leukocyte antigen CD26, is considered to participate in T cell activation. We hypothesized that the activity of DPP IV in serum and expression of CD26 in lymphocytes may be altered in patients with eating disorders. Serum DPP IV activity and the number of CD26 (DPP IV)-positive peripheral blood lymphocytes were measured in 44 patients (anorexia nervosa (AN): n = 21, bulimia (B): n = 23) in four consecutive weekly analyses. The analysis of CD26-positive cells included the characterization of CD26-bright and CD26-dim positive subsets. Additionally, the expression of CD25 (IL-2 Receptor alpha chain) was evaluated to estimate the degree of T cell activation. The same analyses were carried out in healthy female volunteers (HC, n = 20). CD26-positive cells were reduced in patients as compared to healthy controls (mean 40.2% (AN) and 41.1% (B) vs. 47.4% (HC), p < 0.01), while the DPP IV activity in serum was elevated (mean 108.4 U/l (AN) and 91.1 U/l (B) vs. 80.3 U/l (HC), p < 0.01). The potential implications of changes in DPP IV expression and serum activity on--and beyond--immune function are discussed.

Eating disorders: a role for dipeptidyl peptidase IV in nutritional control

Dipeptidyl peptidase IV (DPP IV), a serine protease with broad tissue distribution and known activity in serum, has been postulated to modulate nutrition control by modification or inactivation of peptide hormones operating in the enteroinsular axis. We hypothesized that changes of DPP IV activity in serum are related to the nutrition status of patients with eating disorders. Serum DPP IV activity was measured in 52 patients (28 with anorexia nervosa and 24 with bulimia nervosa) in four consecutive weekly analyses. Simultaneously, the number of CD26 (DPP IV)-positive peripheral blood lymphocytes was counted. The same analyses were carried out in 28 healthy female volunteers. In week 1 and throughout the observation period, DPP IV activity in the sera of patients with anorexia nervosa and, to a lesser extent, those with bulimia nervosa was elevated in comparison to that of healthy controls (week 1: means = 92.8 U/L for anorexia-nervosa patients and 89.3 U/L for bulimia-nervosa patients versus 74.7 U/L for healthy control subjects, P = 0.014; weeks 1-4: 91.8 U/L for anorexia-nervosa patients and 86.2 U/L for bulimia-nervosa patients versus 77.6 U/L for healthy controls, P < 0.001). We assume that the increase in DPP IV serum activity will increase the turnover of distinct peptide hormones with known effects on nutrition control and susceptibility to degradation by DPP IV. The potential impact of an increase in DPP IV activity in serum on satiety and nutrition control contributes to previously reported implications for immune function.

Evidence for an interaction between leptin, T cell costimulatory antigens CD28, CTLA-4 and CD26 (dipeptidyl peptidase IV) in BCG-induced immune responses of leptin- and leptin receptor-deficient mice.

Abstract We assessed changes of the enzyme dipeptidyl peptidase IV (DPP IV, CD26) in the context of leptin or leptin receptor deficiency. C57BL/6 mice, Leptin-deficient mice (ob/ob mice, B6.VLep) and Leptin-receptor-deficient mice (db/db mice, B6.Cgm+/+Lepr) were infected with B. Calmette-Guérin (BCG) and sacrificed three days later. DPP IV activity in serum was higher in ob/ob mice and in db/db mice than in wildtype mice. The expression of DPP IV/CD26 on splenocytes was higher in ob/ob mice than in wildtype animals, and lower in db/db mice, and decreased upon stimulation with BCG in ob/ob mice only. Several T cell antigens including CTLA-4 were expressed aberrantly in ob/ob and in db/db mice. Our observations provide evidence for a relationship between DPP IV and leptin.