In vitro and in vivo evaluation of a pH-, microbiota- and time-based oral delivery platform for colonic release

Several formulation strategies have been proposed for oral colon delivery, particularly for the therapy of inflammatory bowel disease (IBD). However, targeting the large intestine remains a challenging goal. The aim of this study was to develop and evaluate a novel type of drug delivery system, which is based on multiple drug release triggers for reliable performance. The system consists of: (i) a drug core, (ii) an inner swellable low-viscosity hydroxypropyl methylcellulose (HPMC) layer, and (iii) an outer film coating based on a Eudragit® S:high-methoxyl (HM) pectin (7:3 w/w) blend, optionally containing chitosan. Convex immediate release tablets (2 or 4 mm in diameter) containing paracetamol or 5-aminosalicylic acid (5-ASA) were coated in a fluid bed. The double-coated tablets exhibited pulsatile release profiles when changing the release medium from 0.1 N HCl to phosphate buffer pH 7.4. Also, drug release was faster in simulated colonic fluid (SCF) in the presence of fecal bacteria from IBD patients compared to control culture medium from tablets with outer Eudragit® S: HM pectin: chitosan coatings. The latter systems showed promising results in the control of the progression of colitis and alteration of the microbiota in a preliminary rat study.

Periodontal manifestations of inflammatory bowel disease: emerging epidemiologic and biologic evidence

Inflammatory bowel disease and periodontitis are both described as a disproportionate mucosal inflammatory response to a microbial environment in susceptible patients. Moreover, these two conditions share major environmental and lifestyle-related risk factors. Despite this intriguing pathogenic parallel, large-scale studies and basic research have only recently considered periodontal outcomes as relevant data. There are mounting and consistent arguments, from recent epidemiologic studies and animal models, that these two conditions might be related. This article is a comprehensive and critical up-to-date review of the current evidence and future prospects in understanding the biologic and epidemiologic relationships between periodontal status and inflammatory bowel disease.

Increased lymphatic vessel density and lymphangiogenesis in inflammatory bowel disease

BACKGROUND

Involvement of the lymphatic system in inflammatory bowel disease (IBD) has been suggested.

AIMS

To examine the density and distribution of lymphatic vessels (LV) within inflamed and non-inflamed wall sections of IBD patients compared with controls, and to evaluate expression of major lymphangiogenic factors.

METHODS

Ileal and colon specimens of 22 patients with Crohn's disease (CD), 16 patients with ulcerative colitis (UC) and 11 controls were studied. Quantification of LV was performed using immunohistochemistry with podoplanin and D2-40 antibodies on seven randomly selected fields. Mucosal expression of podoplanin and lymphangiogenic factor mRNA was measured using PCR.

RESULTS

In CD patients, lymphatic density was significantly increased in non-inflamed and inflamed ileal (P < 0.01 and P < 0.001) and colonic (P < 0.01 and P < 0.001) mucosa compared to controls. Podoplanin mRNA levels were similar in non-inflamed mucosal areas and controls, whereas a four- and sixfold increase was seen in inflamed ileal and colonic areas (P < 0.05). In UC, lymphatic density increased fourfold in non-inflamed (P < 0.001) and fivefold in inflamed colonic mucosa (P < 0.001) compared with controls. An increase in podoplanin mRNA levels was seen in both non-inflamed and inflamed areas (P < 0.01) compared with controls. In CD and UC, lymphatics were found throughout the inflamed mucosa, including the upper half of the lamina propria. Expression of lymphangiogenic factors was similar in patients and controls.

CONCLUSIONS

Increased density of lymphatic vessels is a constant feature of IBD and is present in non-inflamed areas. It is transmural in CD and confined to the mucosa in UC. Its origin remains unclear.

[Nuclear receptor PPAR and hepatology: pathophysiological and therapeutical aspects]

In last few years, the topic of nuclear receptor has been developed in the field of hepatology allowing envisaging therapeutic strategies for the most frequent chronic liver diseases. Peroxysome proliferator-activated receptors (PPAR) contribute to wide physiological processes within the liver such as lipid/glucid metabolisms, inflammatory response, cell differenciation and cell cycle. In vitro experiments and animal studies showed that PPARalpha discloses anti-inflammatory property and PPARgamma discloses anti-inflammatory, antifibrogenic and antiproliferative properties in the liver. Main available agonists are fibrates (PPARalpha) used for 20 years in cases of lipid metabolism abnormalities and glitazones (PPARgamma) used since 2000 for type 2 diabetes. In terms of therapy, animal studies and human trials have been conducted in steatopathies. However, clinicians have to be aware of potential specific side effects related to glitazones especially on cardiovascular system.

PPARgamma as a new therapeutic target in inflammatory bowel diseases

The peroxisome proliferator activated receptor gamma(PPARgamma) is a nuclear receptor highly expressed in the colon and playing a key role in bacterial induced inflammation. Regulation of colon inflammation by this receptor has been well demonstrated in many experimental models of colitis but also in patients with ulcerative colitis, characterised by impaired expression of PPARgamma confined to their colon epithelial cells. Recent data showing that PPARgamma was the major functional receptor mediating the common aminosalicylate activities in inflammatory bowel diseases (IBD) have also reinforced the roles of this receptor in the control of intestinal inflammation. The aims of this review are to discuss the potential roles of PPARgamma in the physiopathology of IBD, as well as the emerging therapeutic strategies targeting this receptor.

Scaffold attachment factor B1 directly interacts with nuclear receptors in living cells and represses transcriptional activity

Transcriptional activity relies on coregulators that modify the chromatin structure and serve as bridging factors between transcription factors and the basal transcription machinery. Using the DE domain of human peroxisome proliferator-activated receptor gamma (PPARgamma) as bait in a yeast two-hybrid screen of a human adipose tissue library, we isolated the scaffold attachment factor B1 (SAFB1/HET/HAP), which was previously shown to be a corepressor of estrogen receptor alpha. We show here that SAFB1 has a very broad tissue expression profile in human and is also expressed all along mouse embryogenesis. SAFB1 interacts in pull-down assays not only with PPARgamma but also with all nuclear receptors tested so far, albeit with different affinities. The association of SAFB1 and PPARgamma in vivo is further demonstrated by fluorescence resonance energy transfer (FRET) experiments in living cells. We finally show that SAFB1 is a rather general corepressor for nuclear receptors. Its change in expression during the early phases of adipocyte and enterocyte differentiation suggests that SAFB1 potentially influences cell proliferation and differentiation decisions.

A unique PPARgamma ligand with potent insulin-sensitizing yet weak adipogenic activity

FMOC-L-Leucine (F-L-Leu) is a chemically distinct PPARgamma ligand. Two molecules of F-L-Leu bind to the ligand binding domain of a single PPARgamma molecule, making its mode of receptor interaction distinct from that of other nuclear receptor ligands. F-L-Leu induces a particular allosteric configuration of PPARgamma, resulting in differential cofactor recruitment and translating in distinct pharmacological properties. F-L-Leu activates PPARgamma with a lower potency, but a similar maximal efficacy, than rosiglitazone. The particular PPARgamma configuration induced by F-L-Leu leads to a modified pattern of target gene activation. F-L-Leu improves insulin sensitivity in normal, diet-induced glucose-intolerant, and in diabetic db/db mice, yet it has a lower adipogenic activity. These biological effects suggest that F-L-Leu is a selective PPARgamma modulator that activates some (insulin sensitization), but not all (adipogenesis), PPARgamma-signaling pathways.

Attenuation of colon inflammation through activators of the retinoid X receptor (RXR)/peroxisome proliferator-activated receptor gamma (PPARgamma) heterodimer. A basis for new therapeutic strategies

The peroxisome proliferator-activated receptor gamma (PPARgamma) is highly expressed in the colon mucosa and its activation has been reported to protect against colitis. We studied the involvement of PPARgamma and its heterodimeric partner, the retinoid X receptor (RXR) in intestinal inflammatory responses. PPARgamma(1/)- and RXRalpha(1/)- mice both displayed a significantly enhanced susceptibility to 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis compared with their wild-type littermates. A role for the RXR/PPARgamma heterodimer in the protection against colon inflammation was explored by the use of selective RXR and PPARgamma agonists. TNBS-induced colitis was significantly reduced by the administration of both PPARgamma and RXR agonists. This beneficial effect was reflected by increased survival rates, an improvement of macroscopic and histologic scores, a decrease in tumor necrosis factor alpha and interleukin 1beta mRNA levels, a diminished myeloperoxidase concentration, and reduction of nuclear factor kappaB DNA binding activity, c-Jun NH(2)-terminal kinase, and p38 activities in the colon. When coadministered, a significant synergistic effect of PPARgamma and RXR ligands was observed. In combination, these data demonstrate that activation of the RXR/PPARgamma heterodimer protects against colon inflammation and suggest that combination therapy with both RXR and PPARgamma ligands might hold promise in the clinic due to their synergistic effects.

[Peroxisome proliferator-activated receptor (PPAR) gamma: a new target for the treatment of inflammatory bowel disease]

The peroxisome proliferator-activated receptor (PPAR) gamma is highly expressed in the colon mucosa. In vitro, it regulates inflammation.

AIM

To evaluate the anti-inflammatory functions of PPARgamma agonist during a trinitrobenzene sulfonic acid (TNBS)-induced colitis in mice.

METHODS

Colitis was induced in Balb/c mice after intra-rectal administration of TNBS. The intensity of inflammation was assessed 2 and 5 days after colitis induction by macroscopic and histologic scores and by the quantification of colon myeloperoxidase (MPO), IL-1B and TNFalpha mRNA concentrations. The therapeutic role of PPARgamma agonist given by oral gavage was assessed in preventive and treatment modes.

RESULTS

TNBS induced severe macroscopic and histologic lesions, with high mucosal MPO, IL-1B and TNFalpha mRNA concentrations. PPARgamma agonist given preventively or in treatment mode allowed a significant decrease of macroscopic and histologic scores through a normalization of MPO, IL-1B and TNFalpha mRNA concentrations.

CONCLUSION

PPARgamma agonist decreases the intensity of TNBS induced colitis through normalization of IL-1B and TNFalpha expression. PPARgamma agonists may be proposed as new therapeutic agents in inflammatory bowel diseases.