Enteric neuronal density contributes to the severity of intestinal inflammation.

BACKGROUND & AIMS: Enteric neurons have been reported to be increased in inflamed regions of the bowel in patients with inflammatory bowel disease or intestinal neurogangliomatosis. It is impossible to determine whether this hyperinnervation predates intestinal inflammation, results from it, or contributes to its severity in humans, so we studied this process in mice. METHODS: To determine whether the density of enteric neurons determines the severity of inflammation, we studied transgenic mice that have greater than normal (NSE-noggin mice, which overexpress noggin under the control of the neuron-specific enolase promoter) or fewer than normal (Hand2(+/-) mice) numbers of neurons in the enteric nervous system. Colitis was induced with trinitrobenzene sulfonic acid or dextran sulfate sodium, and the intensity of the resulting inflammation in Hand2(+/-) and NSE-noggin mice was compared with that of wild-type littermates. RESULTS: Severity of each form of colitis (based on survival, symptom, and histologic scores; intestinal expression of genes that encode proinflammatory molecules; and levels of neutrophil elastase and p50 nuclear factor κB) were significantly reduced in Hand2(+/-) mice and significantly increased in NSE-noggin animals. Neither mouse differed from wild-type in the severity of delayed-type hypersensitivity (edema, T-cell and neutrophil infiltration, or expression of interleukin-1ß, interferon-γ, or tumor necrosis factor-α) induced in the ears using 2,4-dinitro-1-fluorobenzene. Transgene effects on inflammation were therefore restricted to the gastrointestinal tract. CONCLUSIONS: The severity of intestinal inflammation is associated with the density of the enteric innervation in mice. Abnormalities in development of the enteric nervous system might therefore contribute to the pathogenesis of inflammatory bowel disease.

Expression level of Hand2 affects specification of enteric neurons and gastrointestinal function in mice.

BACKGROUND & AIMS: Hand2 is a basic helix-loop-helix transcription factor required for terminal differentiation of enteric neurons. We studied Hand2 haploinsufficient mice, to determine whether reduced expression of Hand2 allows sufficient enteric neurogenesis for survival, but not for development of a normal enteric nervous system (ENS). METHODS: Enteric transcripts that encode Hand2 and the neuron-specific embryonic lethal abnormal vision proteins HuB, HuC, and HuD were quantified. Immunocytochemistry was used to identify and quantify neurons. Apoptosis was analyzed with the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling procedure. Intracellular microelectrodes were used to record inhibitory junction potentials. Gastrointestinal transit and colonic motility were measured in vivo. RESULTS: Levels of of enteric Hand2 transcripts were associated with genotypes of mice, in the following order: Hand2(+/+) > Hand2(LoxP/+) > Hand2(+/-) > Hand2(LoxP/-). Parallel reductions were found in expression of HuD and in regional and phenotypic manners. Numbers of neurons, numbers of neuronal nitric oxide synthase(+) and calretinin(+), but not substance P(+) or vasoactive intestinal peptide(+) neurons, decreased. No effects were observed in stomach or cecum. Apoptosis was not detected, consistent with the concept that Hand2 inhibits neuronal differentiation, rather than regulates survival. The amplitude of inhibitory junction potentials in colonic circular muscle was similar in Hand2 wild-type and haploinsufficient mice, although in haploinsufficient mice, the purinergic component was reduced and a nitrergic component appeared. The abnormal ENS of haploinsufficient mice slowed gastrointestinal motility but protected mice against colitis. CONCLUSIONS: Reduced expression of factors required for development of the ENS can cause defects in the ENS that are subtle enough to escape detection yet cause significant abnormalities in bowel function.

Aromatase deficiency in a male patient - Case report and review of the literature.

OBJECTIVE: Aromatase, or CYP19A1, is a type II cytochrome CYP450 enzyme that catalyzes the conversion of C19 androgens to C18 estrogens. Its crucial role in both female and male physiology has been deduced from human and animal studies using aromatase inhibitors, genetically altered mice, and patients with aromatase deficiency. The latter is an extremely rare disorder. Its diagnosis is particularly difficult in males, who go through puberty normally and therefore usually present as adults with elevated testosterone, bone abnormalities (e.g., delayed bone age and low bone mass), and metabolic syndrome. In this report, we describe a new case of a male patient with aromatase deficiency harboring a known mutation who presented with less severe clinical and biochemical features. CASE REPORT: The patient presented with low bone mass and delayed bone age after a finger fracture at age 25years. FSH, LH and testosterone levels were normal, but estradiol and estrone levels were absent or barely detectable, raising suspicion for aromatase deficiency. A homozygous c.628G>A mutation in exon 5 was confirmed by direct sequencing. Unlike previously reported cases of aromatase deficiency, he did not display biochemical features of insulin resistance, dyslipidemia, or overweight/obese status. Therapy with estradiol led to the closure of growth plates and a dramatic increase in bone mass. CONCLUSIONS: Here we explore genotype/phenotype associations of this new case compared to cases reported previously. We conclude that the specific nature of mutation c.628G>A, which can potentially result in several different forms of the aromatase enzyme, may lend an explanation to the variable phenotypes associated with this particular genotype.