Rene M. van den Wijngaard

Stimulation of the vagus nerve attenuates macrophage activation by activating the Jak2-STAT3 signaling pathway.

Acetylcholine released by efferent vagus nerves inhibits macrophage activation. Here we show that the anti-inflammatory action of nicotinic receptor activation in peritoneal macrophages was associated with activation of the transcription factor STAT3. STAT3 was phosphorylated by the tyrosine kinase Jak2 that was recruited to the α7 subunit of the nicotinic acetylcholine receptor. The anti-inflammatory effect of nicotine required the ability of phosphorylated STAT3 to bind and transactivate its DNA response elements. In a mouse model of intestinal manipulation, stimulation of the vagus nerve ameliorated surgery-induced inflammation and postoperative ileus by activating STAT3 in intestinal macrophages. We conclude that the vagal anti-inflammatory pathway acts by α7 subunit–mediated Jak2-STAT3 activation.

The mast cell stabiliser ketotifen decreases visceral hypersensitivity and improves intestinal symptoms in patients with irritable bowel syndrome

Background Mast cell activation is thought to be involved in visceral hypersensitivity, one of the main characteristics of the irritable bowel syndrome (IBS). A study was therefore undertaken to investigate the effect of the mast cell stabiliser ketotifen on rectal sensitivity and symptoms in patients with IBS. Methods 60 patients with IBS underwent a barostat study to assess rectal sensitivity before and after 8 weeks of treatment. After the initial barostat, patients were randomised to receive ketotifen or placebo. IBS symptoms and health-related quality of life were scored. In addition, mast cells were quantified and spontaneous release of tryptase and histamine was determined in rectal biopsies and compared with biopsies from 22 age- and gender-matched healthy volunteers. Results Ketotifen but not placebo increased the threshold for discomfort in patients with IBS with visceral hypersensitivity. This effect was not observed in normosensitive patients with IBS. Ketotifen significantly decreased abdominal pain and other IBS symptoms and improved quality of life. The number of mast cells in rectal biopsies and spontaneous release of tryptase were lower in patients with IBS than in healthy volunteers. Spontaneous release of histamine was mostly undetectable but was slightly increased in patients with IBS compared with healthy volunteers. Histamine and tryptase release were not altered by ketotifen. Conclusions This study shows that ketotifen increases the threshold for discomfort in patients with IBS with visceral hypersensitivity, reduces IBS symptoms and improves health-related quality of life. Whether this effect is secondary to the mast cell stabilising properties of ketotifen or H1 receptor antagonism remains to be further investigated. Trial Registration Number NTR39, ISRCTN22504486.

Local immune response in skin of generalized vitiligo patients. Destruction of melanocytes is associated with the prominent presence of CLA+ T cells at the perilesional site.

In situ immune infiltrates in lesional, perilesional, and nonlesional skin biopsies from patients with vitiligo were analyzed by immunohistochemistry and compared with immune infiltrates found in the skin of normal healthy donors and relevant disease controls. An increased influx of activated skin-homing T cells and macrophages were seen in the perilesional biopsies. The overall percentages of cutaneous leukocyte-associated antigen-positive (CLA+) T cells were similar to those found in normal healthy donors. This is compatible with the similar expression of E-selectin. Most strikingly, however, the CLA+ T cells in perilesional skin were mainly clustered in the vicinity of disappearing melanocytes, and 60% to 66% of these interacting T cells expressed perforin and granzyme-B. The perforin+/granzyme-B+ cells were not seen in locations different from that of disappearing melanocytes. Interestingly, the majority of the infiltrating T cells were HLA-DR/CD8+. Another hallmark of the present study is the focal expression of intercellular adhesion molecule (ICAM)-1 and HLA-DR in the epidermis at the site of interaction between the immune infiltrates and the disappearing melanocytes. The data presented in this study are consistent with a major role for skin-homing T cells in the death of melanocytes seen in vitiligo.

Postoperative ileus is maintained by intestinal immune infiltrates that activate inhibitory neural pathways in mice.

BACKGROUND AND AIMS Postoperative ileus after abdominal surgery largely contributes to patient morbidity and prolongs hospitalization. We aimed to study its pathophysiology in a murine model by determining gastric emptying after manipulation of the small intestine. METHODS Gastric emptying was determined at 6, 12, 24, and 48 hours after abdominal surgery by using scintigraphic imaging. Intestinal or gastric inflammation was assessed by immune-histochemical staining and measurement of tissue myeloperoxidase activity. Neuromuscular function of gastric and intestinal muscle strips was determined in organ baths. RESULTS Intestinal manipulation resulted in delayed gastric emptying up to 48 hours after surgery; gastric half-emptying time 24 hours after surgery increased from 16.0 +/- 4.4 minutes after control laparotomy to 35.6 +/- 5.4 minutes after intestinal manipulation. The sustained delay in gastric emptying was associated with the appearance of leukocyte infiltrates in the muscularis of the manipulated intestine, but not in untouched stomach or colon. The delay in postoperative gastric emptying was prevented by inhibition of intestinal leukocyte recruitment. In addition, postoperative neural blockade with hexamethonium (1 mg/kg intraperitoneally) or guanethidine (50 mg/kg intraperitoneally) normalized gastric emptying without affecting small-intestinal transit. The appearance of intestinal infiltrates after intestinal manipulation was associated with increased c-fos protein expression in sensory neurons in the lumbar spinal cord. CONCLUSIONS Sustained postoperative gastroparesis after intestinal manipulation is mediated by an inhibitory enterogastric neural pathway that is triggered by inflammatory infiltrates recruited to the intestinal muscularis. These findings show new targets to shorten the duration of postoperative ileus pharmacologically.

Immunopolarization of CD4 + and CD8 + T Cells to Type-1–Like is Associated with Melanocyte Loss in Human Vitiligo

Vitiligo is an autoimmune condition characterized by loss of epidermal melanocytes. High frequencies of melanocyte-reactive cytotoxic T cells in the peripheral blood of vitiligo patients and the observed correlation between perilesional T-cell infiltration and melanocyte loss in situ suggest the important role of cellular autoimmunity in the pathogenesis of this disease. We isolated T cells from both perilesional and nonlesional skin biopsies obtained from five vitiligo patients, then cloned and analyzed their profile of cytokine production after short-term, nonspecific expansion in vitro. Perilesional T-cell clones (TCC) derived from patients with vitiligo exhibited a predominant Type-1–like cytokine secretion profile, whereas the degree of Type-1 polarization in uninvolved skin-derived TCC correlated with the process of microscopically observed melanocyte destruction in situ. Detailed analysis of broad spectrum of cytokines produced by perilesional- and nonlesional-derived CD4+ and CD8+ TCC confirmed polarization toward Type-1–like in both CD4 and CD8 compartments, which paralleled depigmentation process observed locally in the skin. Furthermore, CD8+ TCC derived from two patients also were analyzed for reactivity against autologous melanocytes. The antimelanocyte cytotoxic reactivity was observed among CD8+ TCC isolated from perilesional biopsies of two patients with vitiligo. Finally, in two of five patients, tetramer analysis revealed presence of high frequencies of Mart-1–specific CD8 T cells in T-cell lines derived from perilesional skin. Altogether our data support the role of cellular mechanisms playing a significant part in the destruction of melanocytes in human autoimmune vitiligo.

A symbiotic concept of autoimmunity and tumour immunity: lessons from vitiligo

Vitiligo is a skin disease in which melanocytes (MCs) are eradicated from lesional epidermis, resulting in disfiguring loss of pigment. MCs are destroyed by MC-reactive T cells, as well as other non-immune and immune components. Similarities exist between the autoimmunity observed in vitiligo and the tumour immunity observed in melanoma immuno-surveillance. An analysis of these mechanisms might lead to the development of new therapies for both vitiligo and melanoma.

Exposure to severe wartime conditions in early life is associated with an increased risk of irritable bowel syndrome: a population-based cohort study.

OBJECTIVES:Stressful events during early life have been suggested to play an important role in the development of the irritable bowel syndrome (IBS). In this study, we evaluate whether an exposure to severe wartime conditions during gestation and in early life are associated with an increased prevalence of IBS.METHODS:We assessed the prevalence of IBS using the Rome II questionnaire among 816 men and women (aged 58±1 years) who were born as term singletons in Wilhelmina Gasthuis, Amsterdam, The Netherlands around the time of World War II.RESULTS:Of a total of 816 participants, 9.6% (n=78, 52F) met the criteria for IBS. Exposure to severe wartime conditions in utero was not associated with the prevalence of IBS in adulthood (8.3%). Early-life exposure to severe wartime conditions was associated with an increased prevalence of IBS. The prevalence of IBS among individuals exposed up to 0.5 years of age, 1 year of age, and 1.5 years of age was 8.1%, 12.5%, and 15.3%, respectively. The increased IBS prevalence was not associated with an increased stress response.CONCLUSIONS:Our data indicate that exposure to severe wartime conditions in early life is associated with an increased risk of developing IBS. To what extent this is attributable to the stressful environment of war, to severe undernutrition, or to the increased prevalence of infectious diseases is, however, unclear.

Intestinal mast cells in gut inflammation and motility disturbances

Mast cells may be regarded as prototypes of innate immune cells that can be controlled by neuronal mediators. Their activation has been implicated in many types of neuro-inflammatory responses, and related disturbances of gut motility, via direct or indirect mechanisms that involve several mechanisms relevant to disease pathogenesis such as changes in epithelial barrier function or activation of adaptive or innate immune responses. Here we review the evidence for the involvement of mast cells in the inflammation of the bowel wall caused by bowel manipulation that leads to motility disturbances such as postoperative gastroparesis and ileus. Also in IBD there is substantial evidence for the involvement of mast cells and a mast cell-mediated neuroimmune interaction showing an increased number and an increased degranulation of mast cells. We discuss the potential of mast cell inhibition as a bona fide drug target to relief postoperative ileus. Further research on mast cell-related therapy either by stabilizing the mast cells or by blocking specific mast cell mediators as adjunctive therapy in IBD is encouraged, bearing in mind that several drugs currently used in the treatment of IBD possess properties affecting mast cell activities. This article is part of a Special Issue entitled: Mast cells in inflammation.

Autoimmune melanocyte destruction in vitiligo

V itiligo is a disorder of pigmentation characterized by the presence of milk-white skin macules. The term vitiligo may have evolved from either the Latin word vitium, meaning fault, or vitelius meaning spotted calf (Kovacs, 1998). Pigment-producing cells (melanocytes) are absent from vitiligo lesions (Le Poole et al, 1993b); their loss represents a key event in the pathogenesis of the disease. Vitiligo lesions can change in size and shape over time and can develop at any age, but in approximately half of all cases the disease onset is before the age of twenty (Lerner, 1959). Clinical presentations include (a) segmental vitiligo, characterized by lesions that occur in a dermatomal, asymmetric distribution (of limited clinical significance); (b) focal vitiligo, characterized by a limited number of small lesions; (c) generalized vitiligo, the most common type of vitiligo, where lesions occur with bilateral, symmetrical distribution; and (d) universal vitiligo, indicating complete or almost complete depigmentation (Mosher et al, 1993). The incidence of this disease varies greatly between populations (from 0.14% to 8.8%), but the worldwide incidence is considered to be between 1% and 2% (Mosher et al, 1993). As well as the enhanced ultraviolet (UV) sensitivity of depigmented spots, vitiligo also is a cosmetically disabling disorder that often leads to psychologic stress (Porter et al, 1979). In addition, due to the occurrence of similar hypopigmented skin lesions in the early phase of leprosy, vitiligo is a true social stigma in countries in which leprosy is endemic. This problem is probably best emphasized by the terminology used in southern India, where vitiligo is known as ven kushtam, meaning “white leprosy” (Mosher et al, 1993). There are three main hypotheses for the pathogenesis of vitiligo: self destruction, neural, and autoimmune (Kovacs, 1998). In a number of recent studies, strong evidence in favor of the autoimmune hypothesis has been obtained. This review will discuss the relevant new evidence for autoimmune melanocyte destruction in vitiligo.

The ICAM-1 antisense oligonucleotide ISIS-3082 prevents the development of postoperative ileus in mice.

Intestinal manipulation (IM) during abdominal surgery triggers the influx of inflammatory cells, leading to postoperative ileus. Prevention of this local muscle inflammation, using intercellular adhesion molecule‐1 (ICAM‐1) and leukocyte function‐associated antigen‐1‐specific antibodies, has been shown to shorten postoperative ileus. However, the therapeutic use of antibodies has considerable disadvantages. The aim of the current study was to evaluate the effect of ISIS‐3082, a mouse‐specific ICAM‐1 antisense oligonucleotide, on postoperative ileus in mice. Mice underwent a laparotomy or a laparotomy combined with IM after treatment with ICAM‐1 antibodies, 0.1–10 mg kg−1 ISIS‐3082, saline or ISIS‐8997 (scrambled control antisense oligonucleotides, 1 and 3 mg kg−1). At 24 h after surgery, gastric emptying of a 99mTC labelled semi‐liquid meal was determined using scintigraphy. Intestinal inflammation was assessed by myeloperoxidase (MPO) activity in ileal muscle whole mounts. IM significantly reduced gastric emptying compared to laparotomy. Pretreatment with ISIS‐3082 (0.1–1 mg kg−1) as well as ICAM‐1 antibodies (10 mg kg−1), but not ISIS‐8997 or saline, improved gastric emptying in a dose‐dependent manner. This effect diminished with higher doses of ISIS‐3082 (3–10 mg kg−1). Similarly, ISIS‐3082 (0.1–1 mg kg−1) and ICAM‐1 antibodies, but not ISIS‐8997 or higher doses of ISIS‐3082 (3–10 mg kg−1), reduced manipulation‐induced inflammation. Immunohistochemistry showed reduction of ICAM‐1 expression with ISIS‐3082 only. ISIS‐3082 pretreatment prevents postoperative ileus in mice by reduction of manipulation‐induced local intestinal muscle inflammation. Our data suggest that targeting ICAM‐1 using antisense oligonucleotides may represent a new therapeutic approach to the prevention of postoperative ileus.