Lysophosphatidylcholine alters enterocyte monolayer permeability via a protein kinase C/Ca2+ mechanism

Uptake of Vitamins D2, D3, D4, D5, D6, and D7 Solubilized in Mixed Micelles by Human Intestinal Cells, Caco-2, an Enhancing Effect of Lysophosphatidylcholine on the Cellular Uptake, and Estimation of Vitamins D' Biological Activities

Vitamins D have various biological activities, as well as intestinal calcium absorption. There has been recent concern about insufficient vitamin D intake. In addition to vitamins D₂ and D₃, there are lesser-known vitamins D₄–D₇. We synthesized vitamins D₅–D₇, which are not commercially available, and then evaluated and compared the mixed micelles-solubilized vitamins D uptake by Caco-2 cells. Except for vitamin D₅, the uptake amounts of vitamins D₄–D₇ by differentiated Caco-2 cells were similar to those of vitamins D₂ and D₃. The facilitative diffusion rate in the ezetimibe inhibited pathway was approximately 20% for each vitamin D type, suggesting that they would pass through the pathway at a similar rate. Lysophosphatidylcholine enhanced each vitamin D uptake by approximately 2.5-fold. Lysophosphatidylcholine showed an enhancing effect on vitamin D uptake by reducing the intercellular barrier formation of Caco-2 cells by reducing cellular cholesterol, suggesting that increasing the uptakes of vitamins D and/or co-ingesting them with lysophosphatidylcholine, would improve vitamin D insufficiency. The various biological activities in the activated form of vitamins D₄–D₇ were estimated by Prediction of Activity Spectra for Substances (PASS) online simulation. These may have some biological activities, supporting the potential as nutritional components.

Gut microbiota-mediated lysophosphatidylcholine generation promotes colitis in intestinal epithelium-specific Fut2 deficiency

BACKGROUND AND AIMS

Previous study disclosed Fucosyltransferase 2 (Fut2) gene as a IBD risk locus. This study aimed to explore the mechanism of Fut2 in IBD susceptibility and to propose a new strategy for the treatment of IBD.

METHODS

Intestinal epithelium-specific Fut2 knockout (Fut2△IEC) mice was used. Colitis was induced by dextran sulfate sodium (DSS). The composition and diversity of gut microbiota were assessed via 16S rRNA analysis and the metabolomic findings was obtained from mice feces via metabolite profiling. The fecal microbiota transplantation (FMT) experiment was performed to confirm the association of gut microbiota and LPC. WT mice were treated with Lysophosphatidylcholine (LPC) to verify its impact on colitis.

RESULTS

The expression of Fut2 and α-1,2-fucosylation in colonic tissues were decreased in patients with UC (UC vs. control, P = 0.036) and CD (CD vs. control, P = 0.031). When treated with DSS, in comparison to WT mice, more severe intestinal inflammation and destructive barrier functions in Fut2△IEC mice was noted. Lower gut microbiota diversity was observed in Fut2△IEC mice compared with WT mice (p < 0.001). When exposed to DSS, gut bacterial diversity and composition altered obviously in Fut2△IEC mice and the fecal concentration of LPC was increased. FMT experiment revealed that mice received the fecal microbiota from Fut2△IEC mice exhibited more severe colitis and higher fecal LPC concentration. Correlation analysis showed that the concentration of LPC was positively correlated with four bacteria-Escherichia, Bilophila, Enterorhabdus and Gordonibacter. Furthermore, LPC was proved to promote the release of pro-inflammatory cytokines and damage epithelial barrier in vitro and in vivo.

CONCLUSION

Fut2 and α-1,2-fucosylation in colon were decreased not only in CD but also in UC patients. Gut microbiota in Fut2△IEC mice is altered structurally and functionally, promoting generation of LPC which was proved to promote inflammation and damage epithelial barrier.

Intestinal permeation enhancers to improve oral bioavailability of macromolecules: reasons for low efficacy in humans

INTRODUCTION

Intestinal permeation enhancers (PEs) are substances that transiently alter the intestinal epithelial barrier to facilitate permeation of macromolecules with low oral bioavailability (BA). While a number of PEs have progressed to clinical testing in conventional formulations with macromolecules, there has been only low single digit increases in oral BA, irrespective of whether the drug met primary or secondary clinical endpoints.

AREAS COVERED

This article considers the causes of sub-optimal BA of macromolecules from PE dosage forms and suggests approaches that may improve performance in humans.

EXPERT OPINION

Permeation enhancement is most effective when the PE is co-localized with the macromolecule at the epithelial surface. Conditions in the GI tract impede optimal co-localization. Novel delivery systems that limit dilution and spreading of the PE and macromolecule in the small intestine have attempted to replicate promising enhancement efficacy observed in static drug delivery models.

New directions in necrotizing enterocolitis with early-stage investigators

The 2019 Necrotizing Enterocolitis (NEC) Symposium expanded upon the NEC Society's goals of bringing stakeholders together to discuss cutting-edge science, potential therapeutics and preventative measures, as well as the patient-family perspectives of NEC. The Symposium facilitated discussions and shared knowledge with the overarching goal of creating "A World Without NEC." To accomplish this goal, new research to advance the state of the science is necessary. Over the last decade, several established investigators have significantly improved our understanding of the pathophysiology of NEC and they have paved the way for the next generation of clinician-scientists funded to perform NEC research. This article will serve to highlight the contributions of these young clinician-scientists that seek to elucidate how immune, microbial and nervous system dysregulation contributes to the pathophysiology of NEC.

Roe-derived phospholipid administration enhances lymphatic docosahexaenoic acid-containing phospholipid absorption in unanesthetized rats

Plasma n-3 fatty acids are important as the supplying pool of n-3 fatty acids to various tissues including the brain, although the relationship between dietary n-3 fatty acids and their molecular species in the plasma are not fully clarified. We investigated the intestinal absorption of docosahexaenoic acid (DHA) derived from fish roe phospholipid (Roe-PL) and compared it with fish oil triacylglycerol and free DHA using unanesthetized lymph-cannulated rats. The DHA absorption from intraduodenally administered three samples were not significantly different, whereas Roe-PL administration resulted in a significantly higher level of DHA in the phospholipid fraction than the other two samples administrations. DHA in Roe-PL at the sn-2 position was less hydrolyzed by pancreatin than by purified phospholipase A2 in vitro and simultaneous administration of free DHA and lysophosphatidylcholine did not produce the same results as the Roe-PL administration. Our results indicate that dietary DHA-containing phospholipid is effective to increase the systemic DHA incorporated into phospholipids via intestinal absorption and biosynthesis.

Intestinal permeation enhancers for oral peptide delivery

Intestinal permeation enhancers (PEs) are one of the most widely tested strategies to improve oral delivery of therapeutic peptides. This article assesses the intestinal permeation enhancement action of over 250 PEs that have been tested in intestinal delivery models. In depth analysis of pre-clinical data is presented for PEs as components of proprietary delivery systems that have progressed to clinical trials. Given the importance of co-presentation of sufficiently high concentrations of PE and peptide at the small intestinal epithelium, there is an emphasis on studies where PEs have been formulated with poorly permeable molecules in solid dosage forms and lipoidal dispersions.

Lysoglyceroglycolipids Improve the Intestinal Absorption of Micellar Fucoxanthin by Caco-2 Cells

To improve the intestinal absorption of fucoxanthin, we evaluated the effects of dietary glyceroglycolipids on the uptake and secretion of fucoxanthin solubilized in mixed micelles by human intestinal Caco-2 cells. Although digalactosyldiacylglycerol and sulfoquinovosyldiacylglycerol suppressed fucoxanthin uptake and secretion, their lyso-types, digalactosylmonoacylglycerol and sulfoquinovosylmonoa cylglycerol, remarkably enhanced them. Thus, some dietary glyceroglycolipids may be potential enhancers of fucoxanthin bioavailability in humans.

Glyceroglycolipids Affect Uptake of Carotenoids Solubilized in Mixed Micelles by Human Intestinal Caco-2 Cells

We previously reported that phospholipids markedly affected the uptake of carotenoids solubilized in mixed micelles by human intestinal Caco-2 cells. In the present study, we found that two classes of dietary glyceroglycolipids and the corresponding lysoglyceroglycolipids affected uptake of β-carotene and lutein by differentiated Caco-2 cells. The levels of carotenoid uptake from micelles containing digalactosyldiacylglycerol or sulfoquinovosyldiacylglycerol were significantly lower than that from control micelles. On the other hand, the uptakes from micelles containing digalactosylmonoacylglycerol or sulfoquinovosylmonoacylglycerol were significantly higher than that from control micelles. In dispersed cells and Caco-2 cells with poor cell-to-cell adhesion, however, the levels of uptake from micelles containing these lyso-lipids were much lower than that from control micelles. The uptake levels from control micelles were markedly decreased depending on the development of cell-to-cell/cell-matrix adhesion in Caco-2 cells, but the uptake levels from the micelles containing these lyso-lipids were not substantially changed, suggesting that the intercellular barrier formed by cell-to-cell/cell-matrix adhesion inhibited the uptake from control micelles, but not from the lyso-lipid-containing micelles. The lyso-lipids appeared to enhance carotenoid uptake by decreasing the intercellular barrier integrity. The results showed that some types of glyceroglycolipids have the potential to modify the intestinal uptake of carotenoids.

Lipid based therapy for ulcerative colitis-modulation of intestinal mucus membrane phospholipids as a tool to influence inflammation

Ulcerative colitis (UC) is the result of an inappropriate colonic inflammatory response triggered by environmental and genetic factors. We have recently shown that mucus from UC patients has a decreased phosphatidylcholine (PC) content, while clinical trials revealed that therapeutic addition of PC to the colonic mucus alleviated the inflammatory activity. The mechanisms behind this are still unclear. We hypothesized that PC has at least two possible functions in the intestine: First, it establishes the surface hydrophobicity of the mucus and therefore protects the underlying tissue against intraluminal aggressors; recent experiments on surgical specimens revealed reduced surface tension and hydrophobicity in UC patients. Second, mucus phospholipids might also be integrated into the plasma membranes of enterocytes and thereby influence the signaling state of the mucosa. PC has been shown to inhibit TNF-α induced pro-inflammatory responses including: (1) assembly of plasma membrane actin; (2) activation of MAP kinases ERK and p38; and (3) activation of NF-κB and synthesis of pro-inflammatory gene products. Other phospholipids like phosphatidylethanolamine or sphingomyelin had no effect. PC also inhibited latex bead phagosome actin assembly, killing of M. tuberculosis in macrophages, and sphingosine-1-phosphate induced actin assembly in macrophages. Collectively, these results provide a molecular foundation that shows PC, firstly, as an anti-inflammatory, and secondly, as a surface hydrophobicity increasing compound with promising therapeutic potential in the treatment of inflammatory bowel disease.

Elevated pro-inflammatory and lipotoxic mucosal lipids characterise irritable bowel syndrome

AIM: To investigate the pathophysiology of irritable bowel syndrome (IBS) by comparing the global mucosal metabolic profiles of IBS patients with those of healthy controls.

METHODS: Fifteen IBS patients fulfilling the Rome II criteria, and nine healthy volunteers were included in the study. A combined lipidomics (UPLC/MS) and metabolomics (GC × GC-TOF) approach was used to achieve global metabolic profiles of mucosal biopsies from the ascending colon.

RESULTS: Overall, lipid levels were elevated in patients with IBS. The most significant upregulation was seen for pro-inflammatory lysophosphatidylcholines. Other lipid groups that were significantly upregulated in IBS patients were lipotoxic ceramides, glycosphingolipids, and di- and triacylglycerols. Among the metabolites, the cyclic ester 2(3H)-furanone was almost 14-fold upregulated in IBS patients compared to healthy subjects (P = 0.03).

CONCLUSION: IBS mucosa is characterised by a distinct pro-inflammatory and lipotoxic metabolic profile. Especially, there was an increase in several lipid species such as lysophospholipids and ceramides.

Pathophysiology of LPS-induced gastrointestinal injury in the rat: role of secretory phospholipase A2

A hydrophobic layer of phosphatidylcholine (PC) overlies and protects the surface of the gastrointestinal (GI) tract, contributing to barrier integrity. During critical illness such as sepsis, gut barrier integrity is compromised, which could be related to degradation of PC. The purpose of this study was to investigate a role for luminal (secretory) phospholipase A2 (sPLA(2)) in LPS-induced GI injury. Rats were treated with LPS (5 mg/kg) or saline for 0.5, 1, 3, and 5 h. The gastric and ileal luminal contents were collected for determination of sPLA(2) activity, and the luminal lipids were analyzed using thin layer chromatography for lyso-PC content. The GI permeability was assessed in vivo with fluorescein-isothiocyanate dextran 4000 and rats were tested with or without a specific sPLA(2) inhibitor. LPS induced significant increases in sPLA(2) activity and lyso-PC content in the gastric and ileal lumens at 5 h. In addition, LPS treated rats showed a significant increase in GI permeability to fluorescein-isothiocyanate dextran in both the stomach and ileum at 5 h, which was prevented by pretreatment with the sPLA(2) inhibitor. In response to LPS, sPLA(2) activity increases in the GI tract lumen where it may degrade the extracellular protective phospholipid layer and membranes, producing injurious lyso-PC and increased GI permeability. Pretreatment with an orally active sPLA(2) inhibitor blocks the LPS-induced increase in GI permeability, and may suggest a new approach to fortify the GI mucosal barrier and prevent complications from endotoxin in trauma and other patients.

Effect of probiotic Lactobacillus rhamnosus GG intervention on global serum lipidomic profiles in healthy adults

AIM: To investigate the effect of three weeks’ intervention with a probiotic Lactobacillus rhamnosus GG (LGG) bacteria on global serum lipidomic profiles and evaluate whether the changes in inflammatory variables (CRP, TNF-α and IL-6) are reflected in the global lipidomic profiles of healthy adults.

METHODS: We performed UPLC/MS-based global lipidomic platform analysis of serum samples (n = 26) in a substudy of a randomised, double-blind, placebo-controlled 3-wk clinical intervention trial investigating the immunomodulatory effects of probiotics in healthy adults.

RESULTS: A total of 407 lipids were identified, corresponding to 13 different lipid classes. Serum samples showed decreases in the levels of lysophosphatidylcholines (LysoGPCho), sphingomyelins (SM) and several glycerophosphatidylcholines (GPCho), while triacylglycerols (TAG) were mainly increased in the probiotic LGG group during the intervention. Among the inflammatory variables, IL-6 was moderately associated by changes in global lipidomic profiles, with the top-ranked lipid associated with IL-6 being the proinflammatory LysoGPCho (20:4). There was a weak association between the lipidomic profiles and the two other inflammatory markers, TNF-α and CRP.

CONCLUSION: This was the first study to investigate the effects of probiotic intervention on global lipidomic profiles in humans. There are indications that probiotic LGG intervention may lead to changes in serum global lipid profiles, as reflected in decreased GPCho, LysoGPCho and SM as well as mainly increased TAG.

Capsaicin-induced increase of intestinal cefazolin absorption in rats

The effect of capsaicin on intestinal cefazolin absorption was examined by means of an in situ closed loop method in rats to clarify whether the vanilloid receptor (TRPV1) is involved in drug absorption driven by passive diffusion. In control experiments with 1 mg/mL cefazolin, the amount of cefazolin absorbed from the closed loop was 15.3+/-1.5 microg/cm in the rat jejunum. The absorption amount was increased to 22.8+/-0.9 and 23.4+/-2.4 microg/cm when capsaicin was applied with cefazolin at concentrations of 10 and 400 microM, respectively. The enhancing effect of capsaicin on cefazolin absorption was suppressed when ruthenium red, a non-selective inhibitor of transient receptor potential (TRP) cation channels, was intravenously infused into the rat during the experiment. Cefazolin accumulation in the intestinal tissue was not altered in the presence of capsaicin. Collectively, the mechanism accounting for the capsaicin-induced increase in the intestinal cefazolin absorption is probably that capsaicin associating with TRPV1 increases the intrinsic permeability of cefazolin in intestine.

Cytotoxicity of Lachesis muta muta snake (bushmaster) venom and its purified basic phospholipase A2 (LmTX-I) in cultured cells

Human envenoming by Lachesis muta muta venom, although infrequent, is rather severe, being characterized by pronounced local tissue damage and systemic dysfunctions. Studies on the pharmacological actions of L. m. muta venom are relatively scant and the direct actions of the crude venom and its purified phospholipase A(2) (PLA(2)) have not been addressed using in vitro models. In this work, we investigated the cytotoxicity of L. m. muta venom and its purified PLA(2) isoform LmTX-I in cultured Madin-Darby canine kidney (MDCK) and in a skeletal muscle (C2C12) cell lines. As revealed by neutral red dye uptake assay, the crude venom (10 or 100 microg/ml) induced a significant decrease in cell viability of MDCK cells. LmTX-I at the concentrations tested (70-270 microg/ml or 5-20 microM) displayed no cytotoxicity in both MDCK and C2C12 cell lines. Morphometric analysis of Feulgen nuclear reaction revealed a significant increase in chromatin condensation (pyknosis), apparent reduction in the number of mitotic nuclei and nuclear fragmentation of some MDCK cells after incubation with L. m. muta venom. Monolayer exposure to crude venom resulted in morphological changes as assessed by scanning electron microscopy. The staining with TRITC-labelled phalloidin showed a marked disarray of the actin stress fiber following L. m. muta venom exposure. In contrast, LmTX-I had no effect on nucleus and cell morphologies as well as on stress fiber organization. These results indicate that L. m. muta venom exerts toxic effects on cultured MDCK cells. The LmTX-I probably does not contribute per se to the direct venom cytotoxicity, these effects are mediated by metalloproteinases/disintegrins and other components of the venom.

Various non-digestible saccharides increase intracellular calcium ion concentration in rat small-intestinal enterocytes

We have previously shown that non-digestible saccharides (NDS) stimulate intestinal Ca absorption via tight junctions. However, the cellular mechanisms activated by the NDS are not yet known. We investigated the effects of four NDS, difructose anhydride (DFA) III, DFAIV, fructo-oligosaccharides, and maltitol, on intracellular Ca signalling in isolated rat small-intestinal enterocytes. The changes in intracellular Ca2+concentration were measured before and after the addition of capric acid (7·5 or 15 mmol/l, a positive control), glycerol, or each NDS (1 or 10 mmol/l) to fura-2-loaded enterocytes. Treatment with capric acid or each NDS caused an immediate and dose-dependent rise in intracellular Ca2+concentration. Mechanical and osmotic stimulation achieved by adding glycerol had no effect on intracellular Ca2+concentration. The intracellular Ca2+concentration in enterocytes treated with DFAIII and fructo-oligosaccharides reached a peak level at about 30 s after stimulation, but those treated with DFAIV and maltitol showed further increases after the initial rapid rise. The maximum change in intracellular Ca2+concentration obtained by the application of maltitol was higher than that of DFAIII at 10 mmol/l. These findings suggest that each of the four NDS directly stimulates rat enterocytes, and increases intracellular Ca2+concentration. Thus, molecular structure may be more important than the size of the NDS in the induction of Ca signalling in the cells.

Effects of lysophosphatidylcholine on monolayer cell permeability of human coronary artery endothelial cells

BACKGROUND

Lysophosphatidylcholine (LysoPC) is a product of phosphatidylcholine hydrolysis by phospholipase A2, which is associated with atherosclerosis. However, the underlying molecular mechanisms are still unclear. The purpose of this study was to determine the effects of LysoPC on monolayer permeability of human coronary artery endothelial cells (HCAECs).

METHODS

HCAECs were cultured with LysoPC in a dose- and time-dependent manner. Monolayer permeability was studied by using a transwell system with a Texas-Red-labeled dextran tracer. The messenger RNA and protein levels of endothelial tight junction proteins were determined with the use of real-time reverse transcriptase-polymerase chain reaction and Western blot analysis, respectively. Superoxide anion levels were determined with the use of fluorescent dye dihydroethidium-based flow cytometry analysis. Activation of mitogen-activated protein kinases was determined by performing Bio-Plex immunoassay.

RESULTS

LysoPC (30 micromol/L) increased monolayer permeability by 53% and decreased the messenger RNA levels of zonula occludens-1, occludin, claudin-1, and junctional adhesion molecule by 44%, 53%, 50%, and 52%, respectively, compared with controls (P < .05). Western blot analysis showed reduced protein levels of these tight junction molecules. LysoPC (15 and 30 micromol/L) also increased superoxide anion production by 54% and 58%, respectively, compared with controls (P < .05). Antioxidant seleno-L-methionine (20 and 30 micromol/L) inhibited LysoPC (30 micromol/L)-induced permeability by 42% and 68%, respectively (P < .05). Furthermore, LysoPC (30 micromol/L) activated c-Jun N-terminal kinase and p38 phosphorylation, but not extracellular signal-related kinase 1/2, within 5 to 10 minutes.

CONCLUSIONS

LysoPC increases monolayer permeability and reduces the expression of tight junction molecules in HCAECs through oxidative stress and activation of c-Jun N-terminal kinase and p38 mitogen-activated protein kinase. The antioxidant can effectively block LysoPC-induced endothelial permeability.

Aerosol delivery of an enhanced helper-dependent adenovirus formulation to rabbit lung using an intratracheal catheter

BACKGROUND

Poor transduction of the ciliated airway epithelium and inefficient airway delivery of viral vectors are common difficulties encountered in lung gene therapy trials with large animals and humans.

METHODS

We delivered a helper-dependent adenovirus vector, incorporating a human epithelial cell-specific expression cassette, to rabbit lung. An intratracheal device was used to aerosolize a moderate dose of virus (5 x 10(11) particles), mixed with the enhancing agent LPC (L-alpha-lysophosphatidylcholine), directly into the airways. Lung mechanics, body weight and temperature, transgene expression and histopathology were studied at day 5.

RESULTS

Transgene expression was seen in the epithelium of large and small airways, from trachea to terminal bronchioles, with a strong tendency toward the right lung. All cell types of the surface epithelium were transduced. Extensive transduction of the epithelium (66% of cells in trachea) was obtained using virus formulated in isotonic 0.1% LPC, while virus formulated in 0.01% LPC transduced fewer cells (24% in trachea). A transient decrease in dynamic lung compliance was observed immediately following aerosol delivery. Fever and mild-to-moderate patchy pneumonia without edema were also observed.

CONCLUSION

These data demonstrate a strategy for efficient and effective transduction of airway epithelium in a large animal.

Various nondigestible saccharides open a paracellular calcium transport pathway with the induction of intracellular calcium signaling in human intestinal Caco-2 cells

Ingestion of soluble nondigestible saccharides increases calcium absorption, and it is suggested that paracellular calcium transport contributes to this effect. However, cellular mechanisms and the contribution of active transport have not been clarified. This study examined the effects of 4 nondigestible saccharides, difructose anhydride (DFA) III, DFAIV, fructooligosaccharides, and raffinose, on active and passive calcium transport, permeability of paracellular pathways, and intracellular calcium signaling in a human intestinal Caco-2 cell monolayer. Net, active, and passive calcium transport were evaluated using (45)Ca. Transepithelial electrical resistance (TEER) and transport of lucifer yellow were measured as indicators of paracellular passage in differentiated Caco-2 cell monolayers incubated with 0-100 mmol/L of the various saccharides. The changes in intracellular calcium ion concentrations ([Ca(2+)](i)) were measured by fura-2 loading before and after the addition of each saccharide (50 or 100 mmol/L). The addition of 100 mmol/L of each saccharide to the apical medium of the Caco-2 cells enhanced net calcium transport without any changes in active calcium transport. Relative TEER was dose dependently and reversibly decreased by the addition of saccharides, and the decreases in TEER were highly correlated with net calcium transport (P < 0.001). Basolateral application of the saccharides had a slight or no effect on indicators of the paracellular pathway. Each saccharide caused an immediate and dose-dependent rise in [Ca(2+)](i) in the cells. The 4 nondigestible saccharides increased net calcium transport in the cells via the paracellular route through tight junctions. The rise in [Ca(2+)](i) induced by these saccharides may be involved in the opening of tight junctions.

A primary dysregulation in the immunoregulatory role of the intestinal mucosal epithelial cell in inflammatory bowel disease pathogenesis? Biology of inflammatory response as tissue pattern entities in Crohn's versus ulcerative colitis

Within a framework of dual involvement of mucosa and submucosa on the one hand, and of the muscularis propria of the bowel wall on the other, it might be valid to consider involvement of the vascular supply as the essential means in itself of not only causing the morphologic lesions in inflammatory bowel disease, but also especially in accounting for persisting patterns of inflammatory response both in ulcerative colitis and in Crohn's disease. Inflammatory bowel disease as a group constitutes a spectrum of biologic and pathobiologic manifestations in terms not only of inflammatory involvement of the bowel wall but also in terms of how the bowel in its turn deals with inflammation as a pathologic lesion in its own right. Parameters of inflammatory bowel activity transcend simple concepts of etiology and pathogenesis as applicable to category disorders such as infections or bowel ischemia. Indeed, the strictly characterized initiation of the inflammatory bowel response as a function of defective regulation of the antigenicity of the luminal contents on the one hand, and on interactions between nitric oxide and free oxygen radicals on the other, might help determine a persistence of tissue damage in inflammatory bowel disease that is either relapsing/remitting or chronic in progression. In a final analysis, perhaps, there might be involved a single central form of pathway induction of dysregulated immune reactivity arising from an early disturbance in activation patterns as induced by the onset of luminal antigenicity at an early or specific-stage, further characterized perhaps by specific forms of intestinal epithelial defects of the bowel mucosa in patients subsequently developing inflammatory bowel disease. Specific genetic markers for disease susceptibility and for therapeutic responsiveness are particularly of interest. The Nucleotide binding oligomerization Domain 2 (NOD2) would recognize microbial lipopolysaccharide or else mark systemic responses to pathogens that are pathogenic to evolving inflammatory bowel disease.