Phenotypic distinctions between neural crest and placodal derived vagal C-fibres in mouse lungs.

Two major types of nociceptors have been described in dorsal root ganglia (DRGs). In comparison, little is known about the vagal nociceptor subtypes. The vagus nerves provide much of the capsaicin-sensitive nociceptive innervation to visceral tissues, and are likely to contribute to the overall pathophysiology of visceral inflammatory diseases. The cell bodies of these afferent nerves are located in the vagal sensory ganglia referred to as nodose and jugular ganglia. Neurons of the nodose ganglion are derived from the epibranchial placodes, whereas jugular ganglion neurons are derived from the neural crest. In the adult mouse, however, there is often only a single ganglionic structure situated alone in the vagus nerve. By employing Wnt1Cre/R26R mice, which express ß-galactosidase only in neural crest derived neurons, we found that this single vagal sensory ganglion is a fused ganglion consisting of both neural crest neurons in the rostral portion and non-neural crest (nodose) neurons in the more central and caudal portions of the structure. Based on their activation and gene expression profiles, we identified two major vagal capsaicin-sensitive nociceptor phenotypes, which innervated a defined target, namely the lung in adult mice. One subtype is non-peptidergic, placodal in origin, expresses P2X2 and P2X3 receptors, responds to α,ß-methylene ATP, and expresses TRKB, GFRα1 and RET. The other phenotype is derived from the cranial neural crest and does not express P2X2 receptors and fails to respond to α,ß-methylene ATP. This population can be further subdivided into two phenotypes, a peptidergic TRKA(+) and GFRα3(+) subpopulation, and a non-peptidergic TRKB(+) and GFRα1(+) subpopulation. Consistent with their similar embryonic origin, the TRPV1 expressing neurons in the rostral dorsal root ganglia were more similar to jugular than nodose vagal neurons. The data support the hypothesis that vagal nociceptors innervating visceral tissues comprise at least two major subtypes. Due to distinctions in their gene expression profile, each type will respond to noxious or inflammatory conditions in their own unique manner.

Nitrooleic acid, an endogenous product of nitrative stress, activates nociceptive sensory nerves via the direct activation of TRPA1.

Transient Receptor Potential A1 (TRPA1) is a nonselective cation channel, preferentially expressed on a subset of nociceptive sensory neurons, that is activated by a variety of reactive irritants via the covalent modification of cysteine residues. Excessive nitric oxide during inflammation (nitrative stress), leads to the nitration of phospholipids, resulting in the formation of highly reactive cysteine modifying agents, such as nitrooleic acid (9-OA-NO(2)). Using calcium imaging and electrophysiology, we have shown that 9-OA-NO(2) activates human TRPA1 channels (EC(50), 1 microM), whereas oleic acid had no effect on TRPA1. 9-OA-NO(2) failed to activate TRPA1 in which the cysteines at positions 619, 639, and 663 and the lysine at 708 had been mutated. TRPA1 activation by 9-OA-NO(2) was not inhibited by the NO scavenger carboxy-PTIO. 9-OA-NO(2) had no effect on another nociceptive-specific ion channel, TRPV1. 9-OA-NO(2) activated a subset of mouse vagal and trigeminal sensory neurons, which also responded to the TRPA1 agonist allyl isothiocyanate and the TRPV1 agonist capsaicin. 9-OA-NO(2) failed to activate neurons derived from TRPA1(-/-) mice. The action of 9-OA-NO(2) at nociceptive nerve terminals was investigated using an ex vivo extracellular recording preparation of individual bronchopulmonary C fibers in the mouse. 9-OA-NO(2) evoked robust action potential discharge from capsaicin-sensitive fibers with slow conduction velocities (0.4-0.7 m/s), which was inhibited by the TRPA1 antagonist AP-18. These data demonstrate that nitrooleic acid, a product of nitrative stress, can induce substantial nociceptive nerve activation through the selective and direct activation of TRPA1 channels.

Cecal Perforation in the Setting of Campylobacter jejuni Infection.

Campylobacter infection is the leading cause of bacterial gastroenteritis worldwide, yet life-threatening complications are extremely rare. We present a 32-year-old previously healthy man who presented with dysentery from Campylobacter jejuni, which was complicated by cecal perforation and secondary bacterial peritonitis.

Low Incidence of Dysplasia and Colorectal Cancer Observed among Inflammatory Bowel Disease Patients with Prolonged Colonic Diversion.

Background: In inflammatory bowel disease (IBD), many scenarios call for fecal diversion, leaving behind defunctionalized bowel. The theoretical risk of colorectal cancer (CRC) in this segment is frequently cited as a reason for resection. To date, no studies have characterized the incidence of neoplasia in the diverted colorectal segments of IBD patients. Methods: A retrospective cohort analysis was conducted for IBD patients identified through a tertiary care center pathology database. Patients that had undergone colorectal diversion and were diverted for ≥ 1 year were included. Incidence of diverted dysplasia/CRC was calculated for Crohn's disease (CD) and ulcerative colitis (UC) with respect to diverted patient-years (dpy) and patient-years of disease (pyd). Results: In total, 154 patients comprising 754 dpy and 1984 pyd were analyzed. Only 2 cases of diverted colorectal dysplasia (CD 1, UC 1) and 1 case of diverted CRC (UC) were observed. In the UC cohort (n = 75), the rate of diversion-associated CRC was 4.5 cases/1000 dpy (95% CI 0.11-25/1000) or 1.5 cases/1000 pyd (95% CI 0.04-8.2/1000). In the CD cohort (n = 79), no patients developed CRC, although a dysplasia rate of 1.9 cases/1000 dpy (95% CI 0.05-11/1000) or 0.77 cases/1000 pyd (95% CI 0.02-4.3/1000) was observed. All patients developing neoplasia had disease duration > 10 years and microscopic inflammation. Conclusions: Diverted dysplasia occurred infrequently with rates overlapping those reported in registries for IBD-based rectal cancers. Neoplasia was undetected in patients with < 10 pyd, regardless of diversion duration, suggesting low yield for endoscopic surveillance before this time.