Long-term effectiveness and acceptability of switching from intravenous to subcutaneous infliximab in patients with inflammatory bowel disease treated with intensified doses: The REMSWITCH-LT study

BACKGROUND

The long-term risk of relapse after switching from intravenous (IV) to subcutaneous (SC) infliximab remains unknown in inflammatory bowel disease (IBD).

AIMS

To assess the long-term effectiveness and acceptability of switching from IV to SC infliximab in patients with IBD treated with or without an intensified IV regimen.

METHODS

We extended the follow-up of the REMSWITCH study including patients with IBD in clinical remission who were switched from IV to SC infliximab (120 mg/2 weeks). Relapse was defined as clinical relapse or faecal calprotectin increase ≥150 μg/g compared to baseline.

RESULTS

After median follow-up of 18 [15-20] months, among 128 patients, rates of relapse were 13.8% (8/58), 18.4% (7/38), 35.3% (6/17) and 86.7% (13/15) at last follow-up (p < 0.001), in those receiving 5 mg/kg/8 weeks, 10 mg/kg/8 weeks, 10 mg/kg/6 weeks and 10 mg/kg/4 weeks at baseline, respectively. Among relapsing patients, dose escalation led to clinical remission in 82.1% (23/28). In multivariable analyses, factors associated with higher risk of relapse were IV infliximab 10 mg/kg/4 weeks (OR = 61.0 [6.1-607.0], p < 0.001) or 10 mg/kg/6 weeks (OR = 4.7 [1.1-20.2], p = 0.017), and decreased (OR = 5.6 [1.5-20.3], p = 0.004) or stable (OR = 5.0 [1.6-15.0], p = 0.009) serum levels of infliximab between baseline and first post-switch visit. Acceptability was improved at 6 months and did not decrease over time (6.9 ± 1.6 before the switch vs. 8.8 ± 1.3 at 6 months and 8.8 ± 1.3 at last follow-up; p < 0.001). No severe adverse events were reported.

CONCLUSIONS

Switching from IV to SC infliximab 120 mg every other week is safe and well accepted leading to low long-term risk of relapse. Tight monitoring and dose escalation should be recommended for patients receiving 10 mg/kg/6 weeks and 4 weeks, respectively.

Infliximab is an effective option in patients with ulcerative colitis previously exposed to full subcutaneous anti-TNF agent: Results from a real-world multicenter study

BACKGROUND

Data on infliximab efficacy in bio-exposed patients with ulcerative colitis (UC) are limited.

AIMS

To evaluate infliximab effectiveness and its predictors in UC patients with prior exposure to subcutaneous (SC) anti-TNF agent.

METHODS

In this multicenter retrospective study (8 centers), we included all consecutive UC patients with prior exposure to subcutaneous anti-TNF, starting infliximab for symptomatic UC, excluding acute severe colitis. Corticosteroid-free clinical remission (CFREM) was assessed at week 14 (W14) and W52 while endoscopic improvement (CFREM + endoscopic Mayo score≤1) was evaluated at W14.

RESULTS

Overall, 104 patients were included (pancolitis=54.8%, primary failure to subcutaneous anti-TNF=57.4%, concomitant immunosuppressant=53.8%, median partial Mayo score at baseline=7[5-8]). The rate of CFREM was 33.6% (35/104) at W14 and 40.4% (42/104) at W52. At W14, endoscopic improvement was achieved in 29.8%(31/104). In multivariable analysis, concomitant immunosuppressant was associated with higher rate of CFREM at W14(OR=2.83[1.06-7.54], p = 0.037) and W52(OR=2.68[1.16-6.22];p = 0.021), while primary failure to a previous subcutaneous anti-TNF agent led to lower rate of CFREM at W14 (OR=0.37[0.14-0.98], p = 0.046). After a median follow-up of 20.9 months[11.7-33.7]), 50.0%(52/104) patients had discontinued infliximab.

CONCLUSION

Infliximab is an effective option in UC patients previously exposed to prior subcutaneous anti-TNF agent and should be used with concomitant immunosuppressant.

Real-world EGFR testing practices for non-small-cell lung cancer by thoracic pathology laboratories across Europe

BACKGROUND

Testing for epidermal growth factor receptor (EGFR) mutations is an essential recommendation in guidelines for metastatic non-squamous non-small-cell lung cancer, and is considered mandatory in European countries. However, in practice, challenges are often faced when carrying out routine biomarker testing, including access to testing, inadequate tissue samples and long turnaround times (TATs).

MATERIALS AND METHODS

To evaluate the real-world EGFR testing practices of European pathology laboratories, an online survey was set up and validated by the Pulmonary Pathology Working Group of the European Society of Pathology and distributed to 64 expert testing laboratories. The retrospective survey focussed on laboratory organisation and daily EGFR testing practice of pathologists and molecular biologists between 2018 and 2021.

RESULTS

TATs varied greatly both between and within countries. These discrepancies may be partly due to reflex testing practices, as 20.8% of laboratories carried out EGFR testing only at the request of the clinician. Many laboratories across Europe still favour single-test sequencing as a primary method of EGFR mutation identification; 32.7% indicated that they only used targeted techniques and 45.1% used single-gene testing followed by next-generation sequencing (NGS), depending on the case. Reported testing rates were consistent over time with no significant decrease in the number of EGFR tests carried out in 2020, despite the increased pressure faced by testing facilities during the COVID-19 pandemic. ISO 15189 accreditation was reported by 42.0% of molecular biology laboratories for single-test sequencing, and by 42.3% for NGS. 92.5% of laboratories indicated they regularly participate in an external quality assessment scheme.

CONCLUSIONS

These results highlight the strong heterogeneity of EGFR testing that still occurs within thoracic pathology and molecular biology laboratories across Europe. Even among expert testing facilities there is variability in testing capabilities, TAT, reflex testing practice and laboratory accreditation, stressing the need to harmonise reimbursement technologies and decision-making algorithms in Europe.

[Giant condyloma acuminatum in pregnancy]

Buschke Lownestein's tumour is a giant acuminate condyloma characterised by its degenerative potential, its invasive nature and its recurrence after treatment. It is a rare condition, transmitted mainly by sexual transmission and induced by to the human papillomavirus (HPV). The discussion will be illustrated by a clinical case The treatment is still under discussion but surgery seems to be the best option. Management during pregnancy is more complex since it must take into account the mother and her fetus. The delivery route is still debated. The post-treatment evolution was satisfactory and without recurrence until the delivery which, due to the antecedent of 3 caesarean sections, was carried out by cesarean section. HPV vaccination, sex education and early treatment of condyloma lesions should prevent and in any case improve the prognosis of this disease.

Defining and Assessing the Reproducibility of Crohn's Disease Endoscopic Lesions: A Delphi-like Method from the GETAID

BACKGROUND AND AIMS

Defining and assessing the reproducibility of Crohn's disease [CD] endoscopic lesions is essential in assessing endoscopic healing.

METHODS

Twelve endoscopic CD experts from the GETAID defined aphthoid erosions [AE], superficial ulcerations [SU], deep ulcerations [DU], stenosis, and fistulas according to a Delphi-like method. Thirty different GETAID physicians declared if they found acceptable each definition. Intra- and inter-observer agreements were investigated using 100 videos with one tagged specific lesion [AE, SU, DU, or sham lesion] read by 15 independent endoscopists at baseline and 1 month later in a randomised order. Video quality was determined by an external reader. According to kappa estimate [κ ±standard error], intra or inter-observer agreement was qualified as 'moderate' [0.4-0.6], 'substantial' [0.6-0.8], or 'almost perfect' [0.8-1.0].

RESULTS

Among 30 different experts, 83% to 97% found acceptable the definitions retrieved from the Delphi-like method. Intra-observer κ was 0.717 [±0.019] for SU, 0.681 [±0.027] for AE, 0.856 [±0.014] for DU, showing 'substantial' agreement. It was 0.801 [±0.016] for any ulceration [DU or SU]. There was a high variability across readers from 'moderate' to 'almost perfect' agreement. Inter-observer κ was 0.548 [±0.042] for SU, 0.554 [±0.028] for AE 0.694 [±0.041] for DU, and 0.705 [±0.042] for any ulceration. Inter-observer agreement increased when reading the 53 high-quality videos: 0.787 [±0.064] [p = 0.001], 0.607 [±0.043] [p = 0.001], and 0.782 [±0.064][p = 0.001] for DU, AE, and any ulceration, respectively.

CONCLUSIONS

Despite variable intra-agreement level across readers, the GETAID definitions for CD endoscopic lesions provided 'substantial' inter-observer agreements, especially in case of high-quality videos.

Early Transmural Response Assessed Using Magnetic Resonance Imaging Could Predict Sustained Clinical Remission and Prevent Bowel Damage in Patients with Crohn's Disease Treated with Anti-Tumour Necrosis Factor Therapy

BACKGROUND

Magnetic resonance imaging [MRI] is a promising tool to evaluate therapeutic efficacy in ileocolonic Crohn's disease [CD].

AIMS

We aimed to assess the feasibility of early MRI evaluation (week 12 [W12]) to predict corticosteroid-free remission [CFREM] at W52 and prevent long-term bowel damage.

METHODS

All patients with active CD needing anti-tumour necrosis factor [anti-TNF] therapy were consecutively enrolled in this multicentre prospective study. MRI was performed before starting therapy, at W12 and W52. CFREM was defined as Crohn's Disease Activity Index < 150, C-reactive protein < 5 mg/L and faecal calprotectin < 250 µg/g, with no switch of anti-TNF agents, no bowel resection and no therapeutic intensification between W12 and W52.

RESULTS

Among 46 patients, 22 [47.8%] achieved CFREM at W52. Anti-TNF agents were able to heal almost all CD lesions as soon as W12 [p < 0.05]. Early transmural response defined as a 25% decrease of either Clermont score (odds ratio [OR] = 7.7 [1.7-34.0], p < 0.001) or Magnetic Resonance Index of Activity (OR = 4.2 [1.3-13.3], p = 0.015) was predictive of CFREM at W52. Achieving at least two items on W12-MRI among ulceration healing, disappearance of enlarged lymph nodes or sclerolipomatosis, ΔADC [apparent diffusion coefficient] > +10% or ΔRCE [relative contrast enhancement] > -30% was associated with a likelihood of CFREM at W52 of 84.6% vs 37.5% in patients without transmural response [p < 0.001]. Early transmural response could prevent bowel damage progression over time using Clermont score (hazard ratio = 0.21 [0.0-0.9]; p = 0.037).

CONCLUSION

Evaluation of early transmural response by MRI is feasible and is a promising end point to monitor therapeutic efficacy in patients with CD.

Impact of a checklist used by pharmacists on hospital antimicrobial use: a patient-level interrupted time series study

BACKGROUND

Antimicrobial misuse leading to drug resistance is a growing concern for clinicians. Improving antimicrobial stewardship programmes through development of new tools could be part of the solution.

AIM

To evaluate antimicrobial use in hospitalized patients after implementation of an antimicrobial checklist for ward-based clinical pharmacists.

METHODS

A checklist based on quality indicators of optimal antimicrobial use was implemented to standardize hospital pharmacists' assessments of antimicrobial therapy. Antimicrobial use metrics from adults hospitalized during the control and intervention periods were assessed in an interrupted time series analysis of individual patient data. The primary endpoint was days of therapy (DOT) for all antimicrobials per 1000 days present for included patients. Secondary endpoints were the DOT of extended-spectrum antimicrobials (DOT-ES), length of therapy of all antimicrobials (LOT) and the number of pharmacist interventions.

FINDINGS

One-thousand six-hundred and nineteen patients were included: 800 and 819 in the pre- and post-checklist implementation periods, respectively. As indicated by the point estimates and their 95% confidence intervals (CIs), there were no changes in trend for DOT, DOT-ES or LOT. A change in level was not found for the DOT, while a change of -118 DOT-ES [-209,-28] and -51 LOT [-97,-4] was documented. Furthermore, pharmacists' interventions regarding antimicrobials increased by 18.7% (14.0, 23.5) and progress notes by 32.3% (27.8, 36.8).

CONCLUSION

An antimicrobial checklist used by ward-based clinical pharmacists did not decrease DOT for all antimicrobials, but decreased DOT-ES and LOT upon its implementation.

Adalimumab for patients with Crohn's disease complicated by intra-abdominal abscess: a multicentre, prospective, observational cohort study

doi:10.1093/ecco-jcc/jjy222 Abstract P528 from the 'Poster presentations' section of the main abstract book has been withdrawn and re-inserted as DOP63 in the 'Late-breaking abstracts' section.

Long-term efficacy and safety of ustekinumab in 122 refractory Crohn's disease patients: a multicentre experience

BACKGROUND

Long-term outcome of ustekinumab in Crohn's disease (CD) has not been evaluated.

AIM

To evaluate the long-term efficacy and safety of ustekinumab and identify the predictive factors of ustekinumab failure-free persistence in a cohort of anti-TNF refractory CD patients.

METHODS

We performed a retrospective multicentre cohort study including all consecutive CD patients who began subcutaneous ustekinumab and presented a clinical response (defined as a significant improvement of CD-related clinical symptoms assessed by the patient's physician leading to continued ustekinumab) during the first year of treatment. Primary outcome was treatment failure defined as withdrawal of treatment due to loss of response, intolerance or need for surgery.

RESULTS

Eighty-eight of the 122 (72%) CD patients beginning ustekinumab from March 2011 to December 2014, responded to ustekinumab and were followed up until November 2016. Median time on ustekinumab was 26.6 (13.4-34.4) months. Forty-seven patients (54%) continued ustekinumab with a clinical response and 38 (43%) stopped treatment (32 for failure, five for remission and one for pregnancy). Endoscopic response was observed in 82% of patients with endoscopic evaluation and mucosal healing in 39%. Ustekinumab failure-free persistence rates were 78% at 12 months, 66% at 24 months and 55% at 36 months. No predictive factor of ustekinumab failure-free persistence was identified. One severe adverse event was observed (anal adenocarcinoma).

CONCLUSION

In this cohort of refractory CD patients receiving long-term ustekinumab therapy, more than 50% of patients continued ustekinumab treatment with no loss of response, intolerance or surgery and with a good safety profile.

Impact of vedolizumab therapy on extra-intestinal manifestations in patients with inflammatory bowel disease: a multicentre cohort study nested in the OBSERV-IBD cohort

BACKGROUND

The effectiveness of vedolizumab as a treatment for extraintestinal manifestations (EIM) is questionable due to its gut-specificity.

AIM

To assess effectiveness of vedolizumab for EIM in patients with inflammatory bowel disease (IBD) in a large real-life experience cohort.

METHODS

Between June and December 2014, 173 patients with Crohn's disease and 121 with ulcerative colitis were treated with vedolizumab. Patients were followed until week 54. EIM activity was assessed at weeks 0, 6, 14, 22, 30 and 54 by using a 3-step scale: complete remission, partial response and no response.

RESULTS

At baseline, 49 (16.7%) patients had EIMs of which 47 had inflammatory arthralgia/arthritis, four had cutaneous lesions and two had both rheumatologic and skin EIM. At week 54, 21 (44.7%) patients had complete remission for inflammatory arthralgia/arthritis and three (75%) for cutaneous EIM. In multivariate analysis, complete remission of inflammatory arthralgia/arthritis was associated with clinical remission of IBD (OR = 1.89, IC95% [1.05-3.41], P = .03) and recent onset of inflammatory arthralgia/arthritis (OR = 1.99, IC95% [1.12-3.52], P = .02). During the follow-up period, 34 (13.8%) patients without any EIM at baseline, developed incident cases of inflammatory arthralgia/arthritis consisting mostly of peripheral arthralgia without evidence of arthritis and 14 (4.8%) incident cases of paradoxical skin manifestation.

CONCLUSION

Vedolizumab therapy is commonly associated with improvement in EIM. This was associated with quiescent IBD and recent EIM. However, paradoxical skin manifestation and inflammatory arthralgia/arthritis may occur upon vedolizumab therapy.

Efficacy and safety of golimumab in Crohn's disease: a French national retrospective study

BACKGROUND

Anti-tumour necrosis factor (TNF) agents have improved the care of Crohn's disease (CD). After the first anti-TNF discontinuation, it is possible to switch to another anti-TNF. Three anti-TNF agents are available for ulcerative colitis (infliximab, adalimumab and golimumab), but only the first 2 have been approved for CD because golimumab has not been studied for this indication.

AIM

To report the efficacy and safety of golimumab in CD.

METHODS

Crohn's disease patients who received golimumab were identified in 12 French tertiary centres and were retrospectively analysed. The primary endpoint was the duration of golimumab treatment before escalation or discontinuation. The clinical response was defined as a decrease of more than 3 points in the Harvey-Bradshaw index or by global physician assessment.

RESULTS

One hundred and fifteen patients were included. The golimumab treatment duration was 9.8 months (0.55-44), and 48.7% of the patients were still under treatment at the end of follow-up. Clinical response was observed in 55.8% of the patients after a mean duration of 3.8 months. The probability of remaining under treatment without escalation at 6, 12 and 24 months was 54.6%, 34.9% and 19.3% respectively. In multivariate analysis, discontinuation of the first anti-TNF agent due to intolerance (odds ratio, OR = 2.16; 95% CI, confidence interval [1.25-3.86]; P = .005) and co-immunosuppression for more than 6 months (OR = 3.98; 95% CI [2.3-7.1]; P < .0001) were predictive factors of efficacy. Six per cent of the patients discontinued treatment due to intolerance.

CONCLUSION

After failure of infliximab or adalimumab for Crohn's disease, golimumab was safe and seemed beneficial in half of the patients.

Inflammatory gastrointestinal diseases associated with PD-1 blockade antibodies

BACKGROUND

Immune check-point blockade agents have shown clinical activity in cancer patients but are associated with immune-related adverse events that could limit their development. The aim of this study was to describe the gastrointestinal immune-related adverse events (GI-irAE) in patients with cancer treated with anti-PD-1.

METHODS

this is a retrospective study of consecutive adult patients who had a suspected GI-irAE due to anti-PD-1 antibodies between 2013 and 2016. Patients were recruited through a pharmacovigilance registry. Patients' data were reviewed by a multidisciplinary committee that included gastroenterologists, oncologists and a pathologist. Quantitative variables are described by median (range), qualitative variable by frequency (percentage).

RESULTS

Forty-four patients were addressed to a Gastroenterology unit for a suspected GI-IrAE. Twenty patients had a confirmed GI-irAE related to anti-PD-1, which occurred 4.2 months (0.2; 22.1) after the initiation of anti-PD-1. GI-IrAE incidence rate under anti-PD-1 treatment was estimated to be 1.5%. Among patients with GI-IrAE, main symptoms were diarrhoea (n = 16, 80%), abdominal pain (n = 13, 65%), nausea and vomiting (n = 11, 55%), intestinal obstruction (n = 1, 5%), and haematochezia (n = 2, 10%). No patient had colectomy. Four distinct categories of GI-irAE were observed: acute colitis (n = 8, 40%), microscopic colitis (n = 7, 35%), upper gastrointestinal tract inflammation (n = 4, 20%) and pseudo-obstruction (n = 1, 5%). Response rates to corticosteroids were 87.5% (7/8) in acute colitis, 57% (4/7) in microscopic colitis and 75% (3/4) in upper gastrointestinal tract inflammation. Median time to resolution was 36 days (6-172) in acute colitis, and 98 days (42-226) in microscopic colitis.

CONCLUSION

This study suggests that GI-irAE are different and less frequent with anti PD-1 than with anti CTLA-4.

One-year effectiveness and safety of vedolizumab therapy for inflammatory bowel disease: a prospective multicentre cohort study

BACKGROUND

We recently showed that vedolizumab is effective in patients with Crohn's disease (CD) and ulcerative colitis (UC) with prior anti-TNF failure in a multicentre compassionate early-access programme before marketing authorisation was granted to vedolizumab.

AIMS

To assess effectiveness and safety of vedolizumab at week 54 in patients UC and CD.

METHODS

Between June and December 2014, 173 patients with Crohn's disease (CD) and 121 with ulcerative colitis (UC) were treated with vedolizumab induction therapy. Among those 294 patients, 272 completed the induction period and were evaluated at the week 14 visit (161 patients with CD and 111 with UC). Disease activity was assessed using the Harvey-Bradshaw Index for CD and the partial Mayo Clinic score for UC. The primary outcome was steroid-free clinical remission at week 54.

RESULTS

At week 54, steroid-free clinical remission rates at week 54 were 27.2% and 40.5% in patients with CD and UC respectively. In addition, the sustained steroid-free clinical remission (from week 14 to week 54) rates were 8.1% and 19.0% respectively. No deaths were observed. Severe adverse events occurred in 17 (7.2%) patients, including six (2.5%) leading to vedolizumab discontinuation.

CONCLUSION

Vedolizumab is able to maintain steroid-free clinical remission in up to one-third of patients with UC and CD at week 54 with a reasonable safety profile. A significant number of patients experienced loss of response during the first year of treatment, particularly in patients with CD.

Faecal chitinase 3-like 1 is a reliable marker as accurate as faecal calprotectin in detecting endoscopic activity in adult patients with inflammatory bowel diseases

BACKGROUND

Faecal biomarkers are emerging tools in the assessment of mucosal healing in inflammatory bowel diseases (IBDs).

AIM

To evaluate the accuracy of faecal chitinase 3-like 1(CHI3L1) compared to calprotectin in detecting endoscopic activity in IBD.

METHODS

Overall, 86 IBD adults underwent colonoscopy consecutively and prospectively, with Crohn's disease Endoscopic Index of Severity (CDEIS) or Mayo endoscopic subscore calculation for ulcerative colitis, and stool collection. Faecal calprotectin was measured using quantitative immunochromatographic testing. Faecal CHI3L1 was quantified by ELISA. CHI3L1 cut-off value was determined using a receiver-operating curve.

RESULTS

In 54 Crohn's disease patients, faecal CHI3L1 (ρ = 0.70, P < 0.001) and calprotectin (ρ = 0.74, P < 0.001) levels correlated with CDEIS and were significantly increased in patients with endoscopic ulceration. In patients with ileal Crohn's disease, faecal CHI3L1 seemed to be better correlated with CDEIS than faecal calprotectin (ρ = 0.78 vs. ρ = 0.62, P < 0.001 for both). CHI3L1 > 15 ng/g detected endoscopic ulceration in Crohn's disease with a sensitivity of 100% and a specificity of 63.6%, compared to faecal calprotectin > 250 μg/g showing a sensitivity of 90.5% and a specificity of 59.1%. In 32 ulcerative colitis patients, faecal CHI3L1 and calprotectin levels correlated with Mayo endoscopic subscore (ρ = 0.44 and 0.61, respectively, P < 0.001 for both) and were significantly increased in ulcerative colitis patients with endoscopic activity. In ulcerative colitis patients, faecal CHI3L1 > 15 ng/g predicted endoscopic activity with a sensitivity of 81.8% and a specificity of 80.0%, compared to faecal calprotectin>250 μg/g showing a sensitivity of 86.4% and a specificity of 80.0%.

CONCLUSION

Faecal CHI3L1 is a reliable biomarker in detecting endoscopic activity in IBD.

Endoscopic Factors Influencing Fecal Calprotectin Value in Crohn's Disease

BACKGROUND AND AIMS

Fecal calprotectin [fcal] is a biomarker of Crohn's disease [CD] endoscopic activity. Identifying the endoscopic situations in which fcal is less reliable remains unexplored. We aimed to determine the endoscopic factors influencing fcal level in CD.

METHODS

Overall, 53 CD patients consecutively and prospectively underwent colonoscopy, with CD Endoscopic Index of Severity [CDEIS] calculation and stool collection. Fcal was measured using a quantitative immunochromatographic test. Correlation analysis was done with Pearson statistics.

RESULTS

Fcal was correlated with CDEIS [0.66, p < 0.001]. In univariate analysis, fcal was correlated with the affected surface [0.65, p < 0.001] and the ulcerated surface [0.47, p < 0.001]. Fcal was significantly associated with ulceration depth, with median fcal of 867.5 µg/g, 1251.0 µg/g, and 1800.0 µg/g, in patients presenting with non-ulcerated lesions, superficial ulcerations [SU], and deep ulcerations [DU], respectively. Lesion locations did not influence fcal. In multivariate analysis, fcal was associated with affected surface [p = 0.04] and the presence of CD lesions. Moreover, fcal increased with the ulceration depth [p = 0.03]. However, ulcerated surface and CD location did not affect fcal. Using a receiver operating characteristic [ROC] curve, we showed that fcal of 400 µg/g was the best compromise between sensitivity [0.76] and specificity [0.77], whereas fcal ≥ 200 µg/g was highly sensitive [0.86] to detect SU or DU.

CONCLUSIONS

Fcal is a very reliable biomarker to detect endoscopic ulcerations in CD. We suggest repeating measurement in case of intermediary results [200-400 µg/g] in daily practice. Fcal level is mostly influenced by the presence of CD lesions [even non-ulcerated], in a depth-related manner and by the affected surface.

Diffusion-weighted magnetic resonance imaging is effective to detect ileocolonic ulcerations in Crohn's disease

BACKGROUND

Magnetic resonance entero-colonography enables accurate assessment of ileocolonic Crohn's disease, but the need for bowel cleansing and rectal enema limits considerably its use in daily practice.

AIM

We evaluated the accuracy of diffusion-weighted magnetic resonance entero-colonography with neither bowel cleansing nor rectal enema to assess endoscopic activity.

METHODS

Forty-four Crohn's disease patients underwent prospectively and consecutively diffusion-weighted magnetic resonance entero-colonography [with apparent diffusion coefficient (ADC) and Clermont score calculation] and ileocolonoscopy [with Crohn's Disease Endoscopic Index of Severity (CDEIS) and Simplified Endoscopic score for Crohn's Disease (SES-CD) calculation].

RESULTS

Mean ADC was inversely correlated with total CDEIS (ρ = -0.40; P = 0.0067) and total SES-CD (ρ = -0.33; P = 0.032). Considering the 194 segments, ADC was inversely correlated with segmental CDEIS (-0.48; P < 0.001) and segmental SES-CD (-0.44; P < 0.001). ADC values were lower in segments with deep ulcers (1.30 ± 0.23) or superficial ulcerations (1.75 ± 0.64) than in non-ulcerated segments (2.15 ± 0.5) (P = 0.001). Using a receiver operating curve, we determined that segmental ADC <1.42 detected endoscopic deep ulcerations with sensitivity = 0.91 and specificity = 0.83 (Area under the curve = 0.84; P < 0.001). Segmental ADC <1.88 detected endoscopic superficial ulcerations with sensitivity = 0.64 and specificity = 0.75. The segmental ADC values decreased when the ulcerations size increased (P = 0.0001). Clermont score correlated with ileal CDEIS (0.63; P < 0.05) and ileal SES-CD (0.58; P < 0.05). Clermont score was higher in ulcerated segments (23.3 ± 8.4) than in non-ulcerated segments (12.4 ± 10.0) (P = 0.006) and increased with ulcers size (P = 0.012). Clermont score >18.9 detected ulcerations with sensitivity = 0.79 and specificity = 0.73.

CONCLUSION

Diffusion-weighted magnetic resonance entero-colonography using apparent diffusion coefficient and Clermont score was effective to indirectly detect endoscopic ulcerations in ileocolonic Crohn's disease.

Diffusion-weighted magnetic resonance imaging in ileocolonic Crohn's disease: validation of quantitative index of activity

OBJECTIVES

Magnetic resonance imaging (MRI) allows accurate assessment of Crohn's disease (CD), but requires gadolinium injection. Diffusion-weighted (DW)-MRI yields comparable performances in small bowel CD. We compared the accuracy of DW-MR enterocolonography (MREC) and the magnetic resonance index of activity (MaRIA), and performed an external validation of the Clermont score in assessing inflammation in CD.

METHODS

This was an observational prospective study of a single-center cohort. A total of 130 CD patients underwent consecutively MREC with gadolinium injection and DWI sequences between July 2011 and December 2012.

RESULTS

Of the 848 evaluated segments (small bowel=352, colon/rectum=496), 175 (20.6%) were active (small bowel=111, colon/rectum=64) defined as MaRIA ≥7. Using a receiver operating characteristic (ROC) curve, we determined an apparent coefficient of diffusion (ADC) threshold of 1.9 × 10(-3) mm(2)/s that yielded a sensitivity and a specificity in discriminating active from nonactive CD of 96.9% and 98.1%, respectively, for the colon/rectum, and 85.9% and 81.6%, respectively, for the ileum. ADC was better correlated to MaRIA ≥7 than related contrast enhancement obtained with injected sequences (P<0.001). The Clermont score (=1.646 × bowel thickness-1.321 × ADC+5.613 × edema+8.306 × ulceration+5.039) was highly correlated with the MaRIA (rho=0.99) in ileal CD but not in colonic CD (rho <0.80). Interobserver agreement was high with regard to ADC measurement (correlation >0.9, P<0.001, and concordance >0.9, P<0001).

CONCLUSIONS

DW-MREC is a reliable tool to assess inflammation in colonic (ADC) and ileal (Clermont score) CD and its use in daily practice would avoid gadolinium injection.

Diffusion-weighted magnetic resonance imaging for detecting and assessing ileal inflammation in Crohn's disease

BACKGROUND

Whether diffusion-weighted imaging (DWI)-MRI is of value in detecting and assessing inflammation of ileal Crohn's disease (CD) remains poorly investigated.

AIM

To compare DWI-MR enterography (MRE) with conventional MRE in estimating inflammation in small bowel CD, to determine an apparent diffusion coefficient (ADC) threshold to differentiate active from non-active lesions and to assess inter-observer agreement.

METHODS

Thirty-one CD patients from the Clermont-Ferrand IBD unit with ileal involvement were consecutively and prospectively included between April and June 2011. All patients underwent DWI-MRI to detect the digestive segment with the most severe lesions, which was then used to calculate the ADC. Qualitative and quantitative results were compared with conventional MRE including MaRIA (Magnetic Resonance Index of Activity) score calculation and independent activity predictors (wall thickening, oedema, ulcers). Each examination was interpreted independently by two radiologists blinded for clinical assessment.

RESULTS

Seventeen patients (54.8%) had active CD as defined by the MaRIA score ≥7. DWI hyperintensity was highly correlated with disease activity evaluated using conventional MRE (P = 0.001). Qualitative analysis of DW sequences determined sensitivity, specificity, positive predictive value and negative predictive value as 100%, 92.9%, 94.4% and 100% respectively. Quantitative analysis using a cut-off of 1.6 × 10(-3) mm(2)/s for ADC yielded sensitivity and specificity values of, respectively, 82.4% and 100%. Inter-observer agreement was high with regard to DWI hyperintensity (κ = 0.69, accuracy rate = 85.7%) and ADC (correlation = 0.74, P < 0.001, and concordance = 0.71, P < 0.001).

CONCLUSION

DWI-MR enterography is a well-tolerated, non-time-consuming and accurate tool for detecting and assessing inflammation in small bowel Crohn's disease.

Methotrexate for psoriasiform lesions associated with anti-tumour necrosis factor therapy in inflammatory bowel disease

BACKGROUND

Psoriasiform lesions associated with anti-tumour necrosis factor (TNF) therapy are frequent in patients with inflammatory bowel disease (IBD). While methotrexate is the most frequently used systemic treatment for psoriasis, its efficacy for psoriasiform lesions related to anti-TNF therapy remains unknown.

AIMS

To assess the efficacy of methotrexate for psoriasiform lesions associated with anti-TNF therapy refractory to topical therapy in IBD patients.

METHODS

The charts of eight patients from the Nancy IBD cohort who developed psoriasiform lesions on anti-TNF therapy were reviewed. Clinical response was defined as a decrease of more than 50% in the lesions covering surface. All patients were followed up by the same experienced dermatologist.

RESULTS

Eight women (seven Crohn's disease) were followed up for a median duration of 29 months (range, 20-45). Of the eight patients receiving methotrexate, three were primary responders without discontinuation of anti-TNF agents. Only one patient had a sustained response at final follow-up and was able to continue both methotrexate and anti-TNF therapy. Of the two other primary responders, one patient had to discontinue anti-TNF because of severe psoriasiform lesions, whereas the other one continued anti-TNF therapy despite persistent skin lesions at final follow-up. Among the five primary nonresponders, four patients had to stop anti-TNF treatment due to disabling skin lesions.

CONCLUSION

Methotrexate does not appear effective in treating psoriasiform lesions associated with anti-TNF therapy refractory to topical therapy in IBD.

Review article: the natural history of postoperative Crohn's disease recurrence

BACKGROUND

Surgical resection of the diseased bowel in Crohn's disease is unfortunately not curative, and postoperative recurrence remains a problem in these patients.

AIM

To review the rates of and risk factors for clinical and endoscopic recurrence in population-based studies, referral centres and randomised controlled trials.

METHODS

We searched MEDLINE (source PUBMED, 1966 to September, 2011).

RESULTS

In randomised controlled trials, clinical recurrence in the first year after surgery occurred in 10-38% of patients, whereas endoscopic recurrence in the first year was reported in 35-85% of patients. In population-based studies, approximately half of patients experienced clinical recurrence at 10 years. In referral centres, 48-93% of the patients had endoscopic lesions (Rutgeerts' score ≥1) in the neoterminal ileum within 1 year after surgery, whereas 20-37% had symptoms suggestive of clinical recurrence. Three years after surgery, the endoscopic postoperative recurrence rate increased to 85-100%, and symptomatic recurrence occurred in 34-86% of patients. Smoking is the strongest risk factor for postoperative recurrence, increasing by twofold, the risk of clinical recurrence. Prior intestinal resection, penetrating behaviour, perianal disease and extensive bowel disease (>50 cm) are established risk factors for postoperative recurrence. Risk factors for postoperative recurrence remain poorly defined in population-based cohorts.

CONCLUSION

Endoscopic and clinical postoperative recurrence remains common in patients with Crohn's disease, and the identification of risk factors may allow targeted strategies to reduce this recurrence rate.

Reverse glial glutamate uptake triggers neuronal cell death through extrasynaptic NMDA receptor activation

Evidence have accumulated that reverse glutamate uptake plays a key role in the pathophysiology of cerebral ischemia. Here, we investigated the effects of glial glutamate transporter dysfunction on neuronal survival using the substrate inhibitor of glutamate transporters, L-trans-pyrrolidine,2-4,dicarboxylate (PDC), that partly mimics reverse glutamate uptake. On mice primary cortical co-cultures of neurons and astrocytes, PDC treatment triggered an elevation of extracellular glutamate concentration, induced neuronal calcium influx and a massive NMDA receptor (NMDAR) mediated-neuronal death without having any direct agonist activity on NMDARs. We investigated the NMDAR subpopulation activated by PDC-induced glutamate release. PDC application led to the activation of both subtypes of NMDARs but the presence of astrocytes was required to activate NMDARs located extra-synaptically. Extrasynaptic NMDAR activation was also confirmed by the loss of neuronal mitochondrial membrane potential and the inhibition of pro-survival p-ERK signalling pathway. These data suggest that reverse glial glutamate uptake may trigger neuronal death through preferential activation of extrasynaptic NMDAR-related pathways.

Neuronal viability is controlled by a functional relation between synaptic and extrasynaptic NMDA receptors

N-methyl-D-aspartate receptors (NMDARs) are critical for synaptic plasticity that underlies learning and memory. But, they have also been described as a common source of neuronal damage during stroke and neurodegenerative diseases. Several studies have suggested that cellular location of NMDARs (synaptic or extrasynaptic) is a key parameter controlling their effect on neuronal viability. The aim of the study was to understand the relation between these two pools of receptors and to determine their implication in both beneficial and/or deleterious events related to NMDAR activation. We demonstrated that selective extrasynaptic NMDAR activation, as well as NMDA bath application, does not activate extracellular signal-regulated kinase (ERK) pathways, but induces mitochondrial membrane potential breakdown and triggers cell body and dendrite damages, whereas synaptic NMDAR activation is innocuous and induces a sustained ERK activation. The functional dichotomy between these two NMDAR pools is tightly controlled by glutamate uptake systems. Finally, we demonstrated that the only clinically approved NMDAR antagonist, memantine, preferentially antagonizes extrasynaptic NMDARs. Together, these results suggest that extrasynaptic NMDAR activation contributes to excitotoxicity and that a selective targeting of the extrasynaptic NMDARs represents a promising therapeutic strategy for brain injuries.

Comparison of the pharmacological properties of GK11 and MK801, two NMDA receptor antagonists: towards an explanation for the lack of intrinsic neurotoxicity of GK11

Over-stimulation of NMDA receptors (NMDARs) is involved in many neurodegenerative disorders. Thus, developing safe NMDAR antagonists is of high therapeutic interest. GK11 is a high affinity uncompetitive NMDAR antagonist with low intrinsic neurotoxicity, shown to be promising for treating CNS trauma. In the present study, we investigated the molecular basis of its interaction with NMDARs and compared this with the reference molecule MK801. We show, on primary cultures of hippocampal neurons, that GK11 exhibits neuroprotection properties similar to those of MK801, but in contrast with MK801, GK11 is not toxic to neurons. Using patch-clamp techniques, we also show that on NR1a/NR2B receptors, GK11 totally blocks the NMDA-mediated currents but has a six-fold lower IC(50) than MK801. On NR1a/NR2A receptors, it displays similar affinity but fails to totally prevent the currents. As NR2A is preferentially localized at synapses and NR2B at extrasynaptic sites, we investigated, using calcium imaging and patch-clamp approaches, the effects of GK11 on either synaptic or extrasynaptic NMDA-mediated responses. Here we demonstrate that in contrast with MK801, GK11 better preserve the synaptic NMDA-mediated currents. Our study supports that the selectivity of GK11 for NR2B containing receptors accounts contributes, at least partially, for its safer pharmacological profile.

A soluble transforming growth factor-beta (TGF-beta ) type I receptor mimics TGF-beta responses

Transforming growth factor-beta (TGF-beta) signaling requires a ligand-dependent interaction of TGF-beta receptors Tau beta R-I and Tau beta R-II. It has been previously demonstrated that a soluble TGF-beta type II receptor could be used as a TGF-beta antagonist. Here we have generated and investigated the biochemical and signaling properties of a soluble TGF-beta type I receptor (Tau beta RIs-Fc). As reported for the wild-type receptor, the soluble Tau beta R-I does not bind TGF-beta 1 on its own. Surprisingly, in the absence of TGF-beta1, the Tau beta RIs-Fc mimicked TGF-beta 1-induced transcriptional and growth responses in mink lung epithelial cells (Mv1Lu). Signaling induced by the soluble TGF-beta type I receptor is mediated via the obligatory presence of both TGF-beta type I and type II receptors at the cell surface since no signal was observed in Mv1Lu-derivated mutants for TGF-beta receptors R-1B and DR-26. The comparison between the structures of TGF-betas and a three-dimensional model of the extracellular domain of Tau beta RI has shown that five residues of the supposed binding site of TGF-beta 1 (Lys(31), His(34), Glu(5), Tyr(91), and Lys(94)) were found with equivalent biochemical properties and similar spatial positions.

Increased expression of transforming growth factor-beta after cerebral ischemia in the baboon: an endogenous marker of neuronal stress?

There has been an increasing interest in recent years in the evaluation of the neuronal and glial responses to ischemic insult. Some cytokines, including transforming growth factor-beta (TGF-beta), that are overexpressed after experimental stroke in rodents are thought to be implicated in the neuronal processes that lead to necrosis. Thus, such cytokines could predict tissue fate after stroke in humans, although data are currently sparse for gyrencephalic species. The current study addressed the expression pattern of TGF-beta1 in a nonhuman primate model of middle cerebral artery occlusion. Focal permanent ischemia was induced for 1 or 7 days in 6 baboons and the following investigations were undertaken: cerebral oxygen metabolism (CMRO2) positron emission tomography studies, magnetic resonance imaging, postmortem histology, and reverse transcription-polymerase chain reaction. The aim of the current study was to correlate the expression of TGF-beta1 to the underlying metabolic and histologic state of the threatened cerebral parenchyma. The authors evidenced increased TGF-beta1 mRNA levels (up to 25-fold) in those regions displaying a moderate (20% to 49%) reduction in CMRO2. The current findings suggest that the greatly enhanced expression of TGF-beta1 in the penumbral zones that surround tissue destined to infarction may represent a robust index of potentially salvageable brain. The current investigation, in the nonhuman primate, strengthens the authors' hypothesis, derived from rodent models, that TGF-beta1 may be involved in the physiopathology of human stroke.

Neuroprotection mediated by glial cell line-derived neurotrophic factor: involvement of a reduction of NMDA-induced calcium influx by the mitogen-activated protein kinase pathway

The glial cell line-derived neurotrophic factor (GDNF) is first characterized for its trophic activity on dopaminergic neurons. Recent data suggested that GDNF could modulate the neuronal death induced by ischemia. The purpose of this study was to characterize the influence of GDNF on cultured cortical neurons subjected to two paradigms of injury (necrosis and apoptosis) that have been identified during cerebral ischemia and to determine the molecular mechanisms involved. First, we demonstrated that both neurons and astrocytes express the mRNA and the protein for GDNF and its receptor complex (GFRalpha-1 and c-Ret). Next, we showed that the application of recombinant human GDNF to cortical neurons and astrocytes induces the activation of the MAP kinase (MAPK) pathway, as visualized by an increase in the phosphorylated forms of extracellular signal-regulated kinases (ERKs). Thereafter, we demonstrated that GDNF fails to prevent apoptotic neuronal death but selectively attenuates slowly triggered NMDA-induced excitotoxic neuronal death via a direct effect on cortical neurons. To further characterize the neuroprotective mechanisms of GDNF against NMDA-mediated neuronal death, we showed that a pretreatment with GDNF reduces NMDA-induced calcium influx. This effect likely results from a reduction of NMDA receptor activity rather than an enhanced buffering or extrusion capacity for calcium. Finally, we also demonstrated that an ERKs activation pathway is necessary for GDNF-mediated reduction of the NMDA-induced calcium response. Together, these results describe a novel mechanism by which the activation of MAPK induced by GDNF modulates NMDA receptor activity, a mechanism that could be responsible for the neuroprotective effect of GDNF in acute brain injury.

Complement anaphylatoxin C3a is selectively protective against NMDA-induced neuronal cell death

The anaphylatoxin C3a is a potent inflammatory polypeptide released at sites of complement activation. To test whether C3a might alter neuronal outcome following an ischemic insult, we determined the effects of purified human C3a on murine primary cortical cell cultures exposed to apoptotic or excitotoxic paradigms. C3a prevented neither serum deprivation-induced apoptotic neuronal death, nor AMPA/kainate-mediated excitotoxicity. However, in mixed cultures of neurons and astrocytes, C3a dose-dependently protected neurons against NMDA toxicity (47% neuroprotection using 100 nM C3a, p < 0.01, n = 12). The neuroprotective effect of C3a was observable only in the presence of astrocytes. These observations suggest that C3a is involved in excitotoxicity-mediated neuronal death through astrocyte stimulation and extend its role beyond immune functions.

The proteolytic activity of tissue-plasminogen activator enhances NMDA receptor-mediated signaling

Tissue-plasminogen activator (t-PA) is now available for the treatment of thrombo-embolic stroke but adverse effects have been reported in some patients, particularly hemorrhaging. In contrast, the results of animal studies have indicated that t-PA could increase neuronal damage after focal cerebral ischemia. Here we report for the first time that t-PA potentiates signaling mediated by glutamatergic receptors by modifying the properties of the N-methyl-D-aspartate (NMDA) receptor. When depolarized, cortical neurons release bio-active t-PA that interacts with and cleaves the NR1 subunit of the NMDA receptor. Moreover, the treatment with recombinant t-PA leads to a 37% increase in NMDA-stimulated fura-2 fluorescence, which may reflect an increased NMDA-receptor function. These results were confirmed in vivo by the intrastriatal injection of recombinant-PA, which potentiated the excitotoxic lesions induced by NMDA. These data provide insight into the regulation of NMDA-receptor-mediated signaling and could initiate therapeutic strategies to improve the efficacy of t-PA treatment in man.

Ischemia-induced interleukin-6 as a potential endogenous neuroprotective cytokine against NMDA receptor-mediated excitotoxicity in the brain

In the brain, the expression of the pleiotropic cytokine interleukin-6 (IL-6) is enhanced in various chronic or acute central nervous system disorders. However, the significance of IL-6 production in such neuropathologic states remains controversial. The present study investigated the role of IL-6 after cerebral ischemia. First, the authors showed that focal cerebral ischemia in rats early up-regulated the expression of IL-6 mRNA, without affecting the transcription of its receptors (IL-6Ralpha and gp130). Similarly, the striatal injection of N-methyl-D-aspartate (NMDA) in rats, a paradigm of excitotoxic injury, activated the expression of IL-6 mRNA. The involvement of glutamatergic receptor activation was further investigated by incubating cortical neurons with NMDA or alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA). NMDA and ionomycin (a calcium ionophore) up-regulated IL-6 mRNA, suggesting that neurons may produce IL-6 in response to the calcium influx mediated through NMDA receptors. The potential role of IL-6 during ischemic/excitotoxic insults was then studied by testing the effect of IL-6 against apoptotic or excitotoxic challenges in cortical cultures. IL-6 did not prevent serum deprivation- or staurosporine-induced apoptotic neuronal death, or AMPA/kainate-mediated excitotoxicity. However, in both mixed and pure neuronal cultures, IL-6 dose-dependently protected neurons against NMDA toxicity. This effect was blocked by a competitive inhibitor of IL-6. Overall, the results suggest that the up-regulation of IL-6 induced by cerebral ischemia could represent an endogenous neuroprotective mechanism against NMDA receptor-mediated injury.

Serine protease inhibitors: novel therapeutic targets for stroke?

Although the thrombolytic activity of tissue-type plasminogen activator (t-PA) may be beneficial in the acute treatment of stroke, recent studies have suggested that this serine protease could also play a critical role in determining the extent of neuronal death after injury to the central nervous system (CNS). This hypothesis is based on several experimental results: t-PA-deficient mice are resistant to excitotoxic neuronal death induced by the intrahippocampal injection of kainate; the infarct volume induced by occlusion of the middle cerebral artery is reduced in t-PA knockout mice; and the intravenous injection of t-PA can under certain circumstances potentiate the infarct volume in animals subjected to middle cerebral artery occlusion. In the CNS, the serine proteases have been identified to occur both in neurons and glial cells. Their enzymatic activity regulates the balance between the accumulation and the degradation of the extracellular matrix. They are involved in many physiologic functions, ranging from synaptic outgrowth during perinatal development to plasticity in adults. For instance, thrombin and t-PA are known to modulate neurite outgrowth and tissue remodeling in the early stages of development. In the adult brain, t-PA may contribute to the late phase of long-term potentiation and to the subsequent synaptic growth in the hippocampal mossy fiber pathway. This balance between the degradation and accumulation of the extracellular matrix may also be integral to various pathologic processes involved in acute brain injury. For example, compounds that modulate the activity of serine proteases exhibit neuroprotective activity. Based on the above, numerous studies have focused on the production and modulation of the endogenously produced serine protease inhibitors, termed serpins, such as type 1 plasminogen activator inhibitor, neuroserpin, and protease nexin-1. In the present review, we will discuss the need to distinguish between the potentially neurotoxic effects of t-PA and its beneficial effect on reperfusion. We will present data supporting the idea that the modulation of serine protease activity may represent a novel and efficient strategy for the treatment of acute cerebral injury in humans.

A transforming growth factor-beta antagonist unmasks the neuroprotective role of this endogenous cytokine in excitotoxic and ischemic brain injury

Various studies describe increased concentrations of transforming growth factor-beta (TGF-beta) in brain tissue after acute brain injury. However, the role of endogenously produced TGF-beta after brain damage to the CNS remains to be clearly established. Here, the authors examine the influence of TGF-beta produced after an episode of cerebral ischemia by injecting a soluble TGF-beta type II receptor fused with the Fc region of a human immunoglobulin (TbetaRIIs-Fc). First, this molecular construct was characterized as a selective antagonist of TGF-beta. Then, the authors tested its ability to reverse the effect of TGF-beta1 on excitotoxic cell death in murine cortical cell cultures. The addition of 1 microg/mL of TbetaRIIs-Fc to the exposure medium antagonized the neuroprotective activity of TGF-beta1 in N-methyl-D-aspartate (NMDA)-induced excitotoxic cell death. These results are consistent with the hypothesis that TGF-beta1 exerts a negative modulatory action on NMDA receptor-mediated excitotoxicity. To determine the role of TGF-beta1 produced in response to brain damage, the authors used a model of an excitotoxic lesion induced by the intrastriatal injection of 75 nmol of NMDA in the presence of 1.5 microg of TbetaRIIs-Fc. The intrastriatal injection of NMDA was demonstrated to induce an early upregulation of the expression of TGF-beta1 mRNA. Furthermore, when added to the excitotoxin, TbetaRIIs-Fc increased (by 2.2-fold, P < 0.05) the lesion size. These observations were strengthened by the fact that an intracortical injection of TbetaRIIs-Fc in rats subjected to a 30-minute reversible cerebral focal ischemia aggravated the volume of infarction. In the group injected with the TGF-beta1 antagonist, a 3.5-fold increase was measured in the infarction size (43.3 +/- 9.5 versus 152.8 +/- 46.3 mm3; P < 0.05). In conclusion, by antagonizing the influence of TGF-beta in brain tissue subjected to excitotoxic or ischemic lesion, the authors markedly exacerbated the resulting extent of necrosis. These results suggest that, in response to such insults, brain tissue responds by the synthesis of a neuroprotective cytokine, TGF-beta1, which is involved in the limitation of the extent of the injury. The pharmacologic potentiation of this endogenous defensive mechanism might represent an alternative and novel strategy for the therapy of hypoxic-ischemic cerebral injury.

Transforming growth factor-beta1 as a regulator of the serpins/t-PA axis in cerebral ischemia

The tissue type plasminogen activator (t-PA) is a serine protease that is involved in neuronal plasticity and cell death induced by excitotoxins and ischemia in the brain. t-PA activity in the central nervous system is regulated through the activation of serine protease inhibitors (serpins) such as the plasminogen activator inhibitor (PAI-1), the protease nexin-1 (PN-1), and neuroserpin (NSP). Recently we demonstrated in vitro that PAI-1 produced by astrocytes mediates the neuroprotective effect of the transforming growth factor-beta1 (TGF-beta1) in NMDA-induced neuronal cell death. To investigate whether serpins may be involved in neuronal cell death after cerebral ischemia, we determined, by using semiquantitative RT-PCR and in situ hybridization, that focal cerebral ischemia in mice induced a dramatic overexpression of PAI-1 without any effect on PN-1, NSP, or t-PA. Then we showed that although the expression of PAI-1 is restricted to astrocytes, PN-1, NSP, and t-PA are expressed in both neurons and astrocytes. Moreover, by using semiquantitative RT-PCR and Western blotting, we observed that only the expression of PAI-1 was modulated by TGF-beta1 treatment via a TGF-beta-inducible element contained in the PAI-1 promoter (CAGA box). Finally, we compared the specificity of TGF-beta1 action with other members of the TGF-beta family by using luciferase reporter genes. These data show that TGF-beta and activin were able to induce the overexpression of PAI-1 in astrocytes, but that bone morphogenetic proteins, glial cell line-derived neutrophic factor, and neurturin did not. These results provide new insights into the regulation of the serpins/t-PA axis and the mechanism by which TGF-beta may be neuroprotective.

Up-regulation of a serine protease inhibitor in astrocytes mediates the neuroprotective activity of transforming growth factor beta1

Serine proteases play a key role in the fundamental biology of the central nervous system (CNS), and recent data suggest their involvement in the pathophysiology of neurodegenerative diseases. Little is known about the physiological regulation of these proteases in the CNS. Among the multiple growth factors present in the brain, transforming growth factor beta1 (TGF-beta1) has been described as an injury-related growth factor. However, its beneficial or deleterious role remains unclear. In the present study, we investigated the influence of TGF-beta1 in apoptosis and necrosis, two mechanisms involved in ischemic neuronal death. We show that TGF-beta1 exerts a neuroprotective role restricted to necrosis induced by N-methyl-D-aspartate. This effect is observable only in the obligatory presence of TGF-beta1-responsive astrocytes. We demonstrate that this neuroprotective activity is mediated through an up-regulation of a serine protease inhibitor (PAI-1) in astrocytes. These results underline the involvement of serine proteases and extracellular matrix components such as the PAI-1/t-PA axis in the excitotoxic cascade. Moreover, regardless of the underlying mechanisms of t-PA involvement in excitotoxic injury, our observations might warn against the use of tissular plasminogen activator as an alternative therapy for the treatment of hypoxic-ischemic injury in the brain.

Evidence of type I and type II transforming growth factor-beta receptors in central nervous tissues: changes induced by focal cerebral ischemia

The peptides of the transforming growth factor-beta (TGF-beta) family transduce their signal through ligand-induced heteromeric complexes that consist of type I and type II serine/threonine kinases. Both TGF-beta receptors are abundant in many peripheral tissues, but clear evidence of their expression in cortical astrocytes and neurons has not been published so far. In this study, we investigated the expression of type I and type II TGF-beta receptors and their potential ligands (TGF-beta1, TGF-beta2, and TGF-beta3) in the CNS by using RT-PCR and immunohistochemistry. Moreover, to further the study of those cell types that exhibit TGF-beta isoforms and related receptors, we examined through the use of RT-PCR whether cortical neurons and astrocytes in culture express the mRNAs for TGF-betas and their receptors. We show that the three TGF-beta isoform mRNAs are present in the CNS. However, although astrocytes in culture display all three isoforms, neurons in culture express only TGF-beta2. We have demonstrated that both type I and type II TGF-beta receptor mRNAs and proteins are present in the CNS and in cultures of cortical neurons and astrocytes. Thus, TGF-betas may act as autocrine and paracrine signals in the CNS between both neurons and astrocytes via the same receptor systems as those found in peripheral tissues. TGF-beta1 has been shown to be induced following hypoxic-ischemic brain injury and may play a critical role in the pathophysiology of degenerative processes in the CNS. In the present investigation, we confirmed that the expression of TGF-beta1 was increased markedly up until 24 h and thereafter was stable over the first 3 days following permanent occlusion of the middle cerebral artery in mice. However, whereas the expression of the type I TGF-beta receptor was not altered by the ischemic insult, the pattern of the type II TGF-beta receptors was modified dramatically in the ischemic area 3 days after the occlusion. These data show that, even if ligands are present, they may not be able to transduce their signal. Finally, the present study clearly demonstrates that a knowledge of the expression of ligand-specific receptors following brain injury is a fundamental step in clarifying the involvement of cytokines in neurodegenerative diseases.

Membrane-delimited modulation of NMDA currents by metabotropic glutamate receptor subtypes 1/5 in cultured mouse cortical neurons

1. Modulation of NMDA receptors by metabotropic glutamate receptors (mGluRs) in cultured mouse cortical neurons was investigated using whole-cell and single-channel recordings. 2. NMDA whole-cell current was reversibly attenuated by selective mGluR1/5 agonists (S)-3-hydroxyphenylglycine (3HPG; 10-200 microM), (S)-3,5-dihydroxyphenylglyeine (S-DHPG; 100 microM) and other mGluR agonists: (1S,3R)-1-aminocyclopentane-1,3-decarboxylic acid (1S,3R-ACPD; 200 microM), quisqualate (10 microM) and (2S,1'S,2'S)-2-(carboxycyclopropyl)glycine (L-CCG-I; 100 microM). 3. The attenuation of NMDA current by 3HPG was totally eliminated by the mGluR antagonist (RS)-alpha-methyl-4-carboxyphenylglycine (MCPG; 500 microM) and by the selective mGluR1/5 antagonist (S)-4-carboxyphenylglycine (4CPG; 300 microM). 4. mGluR2/3 agonists (2S,1'R,2'R'3'R)-2-(2,3-dicarboxycyclopropyl)glycine (DCG-IV; 3 microM), (S)-4-carboxy-3-hydroxyphenylglycine (4C3HPG; 100-200 microM) and (S)-4-carboxyphenylglycine (4CPG; 300 microM) did not reduce NMDA current. 5. The NMDA-induced increase in intracellular free Ca2+ measured by fura-2 Ca2+ imaging was attenuated by 3HPG (300 microM). 6. The suppression of NMDA current by 3HPG was not affected by treatments that altered intracellular Ca2+ or cAMP levels, or by the protein kinase inhibitor, staurosporine (0.1-0.5 microM). 7. The open probability (NPo) of the NMDA receptor channel in excised outside-out patches was attenuated by 3HPG but not by 4C3HPG. This 3HPG effect was blocked by MCPG. 8. The 3HPG-induced reduction of NMDA whole-cell and single-channel currents was prevented by GDP beta S (200-400 microM). Intracellular dialysis of GTP gamma S (100 microM) also reduced NMDA whole-cell current, and rendered irreversible further reduction induced by 3HPG. 9. These data suggest that a selective activation of mGluR1/5 downmodulates the NMDA receptor channel in a membrane-delimited manner, mediated by G proteins, but not by diffusible second messengers.

DCG-IV selectively attenuates rapidly triggered NMDA-induced neurotoxicity in cortical neurons

Molecular cloning has revealed the existence of at least eight subtypes of metabotropic glutamate receptors (mGluRs). We examined the effect of (2S,1'R,2'R,3'R)-2-(2,3-dicarboxycyclopropyl)glycine (DCG-IV), a selective agonist of the mGluR 2/3 subtype, on excitotoxicity in mouse cortical cell cultures. Addition of DCG-IV to the exposure medium partially attenuated the rapidly triggered excitotoxic death induced by a 5 min exposure to 200 microM NMDA. This neuroprotective effect was reversed by coapplication of alpha-methyl-4-carboxyphenylglycine (MCPG), an antagonist of mGluRs, by pertussis toxin pretreatment and also by preincubation with dibutyryl cAMP, a stable analogue of cAMP. These results suggest that the activation of mGluR 2/3 is neuroprotective in our system. However, DCG-IV did not attenuate the slowly triggered neuronal death induced by 24 h exposure to low concentrations of NMDA, alpha-amino-1,3-cyclopentanedicarboxylic acid (AMPA) or kainate. The failure of DCG-IV to block slowly triggered NMDA neurotoxicity is likely due to weak NMDA agonist activity, as demonstrated in whole-cell recording.

The inhibitory mGluR agonist, S-4-carboxy-3-hydroxy-phenylglycine selectively attenuates NMDA neurotoxicity and oxygen-glucose deprivation-induced neuronal death

We examined the effect of two novel phenylglycine derivative drugs on excitotoxicity in murine cortical cell cultures: S-4-carboxy-3-hydroxy-phenylglycine (4C3HPG), a selective agonist of mGluRs 2/3 and an antagonist at mGluRs 1/5, and S-3 hydroxy-phenylglycine (3HPG), an agonist of mGluRs 1/5. 4C3HPG attenuated slowly-triggered NMDA-induced excitotoxic neuronal death, as well as the death induced by combined oxygen-glucose deprivation, but did not affect slowly-triggered excitotoxicity induced by AMPA or kainate. As expected, 4C3HPG also reduced NMDA-induced increases in cAMP in near-pure neuronal cultures, and the protective effect of 4C3HPG on NMDA toxicity could be reversed by adding 8-(4-chlorophenylthio)-adenosine 3':5'-cyclic-monophosphate (CPT cAMP) to the exposure medium. In contrast, 3HPG did not did not have any protective effects in these paradigms; in fact, slowly-triggered NMDA-induced excitotoxicity and the neuronal cell death induced by oxygen-glucose deprivation were potentiated. These results are consistent with the idea that the "inhibitory" mGluRs 2/3 exert a negative modulatory action on NMDA receptor-mediated excitotoxicity via reduction in neuronal cAMP levels.