That *could be* Staph or Strep species seeding your intestines and causing all kind of havoc.
www.ncbi.nlm.nih.gov/pmc/articles/PMC555745/Discussion
Our knowledge about
the etiology of ulcerative colitis is still limited. Although some theories about
its origins have been advanced, such as genetic predisposition, autoimmune disorders, infection, and so on [23,24], the precise pathogenesis needs to be further understood. In clinical practice, we noted a close association between CS and UC in some patients and their UC was significantly improved after having removed sinus pathology (data not shown). The results of animal experiments verified our speculation: superantigen SEB from sinusitis cooperated with ingested antigen to induce intestinal sensitization. Challenge with the obligate antigen initiated colonic mucosal inflammation as well as the clinical symptom diarrhea. Book DT et al [25] also noted the same phenomenon and suggested that IBD was more prevalent in those people with chronic sinusitis than in other populations.
Rhinosinuses are empty cavities lined with mucosa. The anatomic feature, only having a small ostium, makes them very easily to be blocked and subsequently infected. Infection with S. aureus in sinuses is frequently encountered [4,5]. Thus, chronically infected sinuses may be a source of SEB that is released to nasal cavity frequently. A mucus blanket on the surface of nasal mucosa naturally traps small particles from air and the secretions from sinuses and removes them subsequently. Since the direction of the locomotion of the mucus blanket is backward, people sometimes swallow the secretions into the gastrointestinal tract (e.g., during sleep).
There are many toxic substances in the secretions from chronic sinusitis. SEB is one that has been well characterized. The unique feature of SEB is that it can down regulate intestinal barrier function [6,13], activate T lymphocytes without the help from antigen presenting cells to activate T cells. Superantigens bind directly to MHC class II molecules and to a subset of T-cell receptor (TCR) Vβ chains [26,27]. Unlike conventional antigens, superantigens do not require processing by antigen-presenting cells to activate immune cells [31]. Administration of superantigen results in initial selective expansion of T cells that bear specific Vβ chains that recognize the superantigen, followed by their deletion [29]. Another unique feature of superantigen is that it mutes T suppression cell function and promotes Th1/Th2 skewing [30]. It primes an environment to develop sensitization in local tissue. The results in the present animal experiments are consistent with previous studies. Mice treated with SEB-containing SWF and OVA developed intestinal sensitization, but not in those mice treated with only OVA, or SEB-depleted SWF plus OVA. This finding demonstrates that SEB plays a crucial role in the sensitization of the intestinal mucosa to luminal antigen in these mice. Louini D et al [31] reported that SEB also directly sensitized skin and caused Th2 pattern inflammation in the local skin.
Intestinal epithelial cells form a barrier between the luminal contents and the subepithelial region. The barrier restricts substances to be absorbed. It only allows some small molecules such as water to pass it freely. Antigens are macromolecular proteins that are not allowed to be absorbed before being digested to small peptides or amino acids under normal physiological conditions. But in reality, intact antigens do pass the intestinal barrier to reach lamina propria to induce inappropriate immune reactions under certain circumstance. How antigens cross the intestinal epithelial barrier is still a mystery. By introducing both SWF and HRP to mouse gastrointestinal tract, intact HRP in the colonic tissue was increased nearly 11 times compared to control. The results implicate that superantigen SEB is one of the factors that facilitate antigens to be absorbed without destroying their antigenicity. Lu et al also reported that SEB significantly increased colonic mucosal permeability in a mouse study [13].
We have begun to appreciate that food allergy plays a role in the inflammation of intestinal mucosa [32]. The results of this animal model support that inappropriate immune reactions initiate intestinal inflammation. Simply delivering OVA to gastrointestinal tract did not show sensitization in the mice while the combination of SEB-containing SWF and OVA induced sensitization in the colonic mucosa. Based on these data, we suggest that SEB facilitate sensitization of the intestinal mucosa to OVA. The mechanism behind this phenomenon might be that SEB increases permeability of the intestinal mucosa [6,13]. Thus OVA in the intestinal lumen can be transported to deep region of the mucosa. This exogenous protein then contacts the local immune cells to initiate inappropriate immune reactions and sensitizes the mucosa subsequently. The results of challenge with OVA show extensive inflammation in the colonic mucosa in this study. The inflammatory changes may be a result of local mast cell degranulation in response to OVA challenge. Mast cells release chemical mediators such as histamine that is able to increase vascular permeability and to induce edema in the tissue that was noted in the present study and also reported elsewhere [33].
In chronic allergic diseases such as asthma, during continuous antigen exposure, eosinophils are primed by IL-5 and attracted by chemokines, infiltrating the local tissue [34]. We also observed extensive eosinophil infiltration in the colonic tissue after three challenges with specific antigen OVA in the present study. These eosinophils are believed to be responsible for the late phase of the allergic reaction, producing the major basic protein which is toxic to the epithelium [34]. The micro-ulcers on the surface of colonic mucosa may be caused by eosinophil activation. Supportive evidence acquired from EM observation demonstrates that most eosinophils have been activated by showing extensive degranulation. We also noted this phenomenon in the jejunal mucosa in the late phase reaction in a rat model of food allergy [32].
Marked mast cell hyperplasia in the colonic tissue was observed in this study. In general, mast cell numbers in tissues are relatively constant, even though mast cell hyperplasia is observed in both the inflammatory and in repair/remodeling stage of various inflammatory disorders [35]. The functional significance of the accumulation of mast cells in these processes is largely unknown. In allergy, apart from their classical role in eliciting the early phase, mast cells also have an important role in late and chronic stages as we observed in a previous study [32]. In these stages they may interact with and be activated by infiltrated inflammatory cells and by resident structural cells such as epithelial cells, smooth muscle cells and fibroblasts. In the case of allergic reaction, mast cells are mainly activated by the mechanism of IgE mediated FcεRI bridging that accounts for the mast cell activation in the present study. The roles of mast cells in the late phase reactions may be amplified by eosinophils, platelets and neutrophils [36]. If a sensitized patient frequently ingests an obligate antigen unconsciously whereas the allergic reaction only reaches subclinical level, an early inflammation may progress without being noticed until reaching the advanced stage. The data also show that the degranulation type of mast cells and eosinophils in this study is mainly piecemeal. It indicates that the nature of the degranulation type belongs to a chronic process [37]. The local inflammation may progress to chronic status in the tissue without any further medical intervention.
Striking epithelial damage of colonic mucosa of the sensitized mice after challenge with OVA was observed in this study. This phenomenon has been well-documented in airway allergy [38]. Although ulcers are one of the main clinical signs in inflammatory bowel diseases, the etiology is not clear. There have not been many studies considering an association between the ulcers and allergic reactions in the gastrointestinal tract. Eosinophil released major basic protein is suggested to be the major offender to cause epithelial cell exfoliation in the airway mucosa [38]. The erosion and prominent damage to the epithelial barrier can explain the phenomenon of bacterial adhering to and penetrating to colonic mucosa in this study. These bacteria are commensal bacteria. They usually are not considered pathogenic. The damaged epithelium may provide an entry port for the colonizing bacteria to invade the colonic mucosa and to establish an infection.
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Conclusion
In summary, we reported a murine model of ulcerative colitis in this paper that was induced with sinusitis-derived SEB and OVA sensitization followed by repeat challenges with specific antigen OVA. The histopathology of the colonic mucosa included inflammatory cell infiltration, activation of mast cell/eosinophil, epithelial barrier damage, micro-ulcer formation on the surface of colonic mucosa, bacteria trans
location and abscesses formation in the subepithelial region.
Post Edited (PathogenKiller) : 5/21/2013 1:15:33 PM (GMT-6)