Serum and Urine Metabolomic Profiling of Newly Diagnosed Treatment-Naïve Inflammatory Bowel Disease Patients

BACKGROUND AND AIMS

Inflammatory bowel disease (IBD) is a prevalent chronic noncurable disease associated with profound metabolic changes. The discovery of novel molecular indicators for unraveling IBD etiopathogenesis and the diagnosis and prognosis of IBD is therefore pivotal. We sought to determine the distinctive metabolic signatures from the different IBD subgroups before treatment initiation.

METHODS

Serum and urine samples from newly diagnosed treatment-naïve IBD patients and age and sex-matched healthy control (HC) individuals were investigated using proton nuclear magnetic resonance spectroscopy. Metabolic differences were identified based on univariate and multivariate statistical analyses.

RESULTS

A total of 137 Crohn's disease patients, 202 ulcerative colitis patients, and 338 HC individuals were included. In the IBD cohort, several distinguishable metabolites were detected within each subgroup comparison. Most of the differences revealed alterations in energy and amino acid metabolism in IBD patients, with an increased demand of the body for energy mainly through the ketone bodies. As compared with HC individuals, differences in metabolites were more marked and numerous in Crohn's disease than in ulcerative colitis patients, and in serum than in urine. In addition, clustering analysis revealed 3 distinct patient profiles with notable differences among them based on the analysis of their clinical, anthropometric, and metabolomic variables. However, relevant phenotypical differences were not found among these 3 clusters.

CONCLUSIONS

This study highlights the molecular alterations present within the different subgroups of newly diagnosed treatment-naïve IBD patients. The metabolomic profile of these patients may provide further understanding of pathogenic mechanisms of IBD subgroups. Serum metabotype seemed to be especially sensitive to the onset of IBD.

Controversies in the management of anti-TNF therapy in patients with Crohn's disease: a Delphi consensus

BACKGROUND

Despite research, there are still controversial areas in the management of Crohn's disease (CD).

OBJECTIVE

To establish practical recommendations on using anti-tumour necrosis factor (TNF) drugs in patients with moderate-to-severe CD.

METHODS

Clinical controversies in the management of CD using anti-TNF therapies were identified. A comprehensive literature review was performed, and a national survey was launched to examine current clinical practices when using anti-TNF therapies. Their results were discussed by expert gastroenterologists within a nominal group meeting, and a set of statements was proposed and tested in a Delphi process.

RESULTS

Qualitative study. The survey and Delphi process were sent to 244 CD-treating physicians (response rate: 58%). A total of 14 statements were generated. All but two achieved agreement. These statements cover: (1) use of first-line non-anti-TNF biological therapy; (2) role of HLA-DQA1*05 in daily practice; (3) attitudes in primary non-response and loss of response to anti-TNF therapy due to immunogenicity; (4) use of ustekinumab or vedolizumab if a change in action mechanism is warranted; (5) anti-TNF drug level monitoring; (6) combined therapy with an immunomodulator.

CONCLUSION

This document sought to pull together the best evidence, experts' opinions, and treating physicians' attitudes when using anti-TNF therapies in patients with CD.

Activity of Spanish gastroenterology units before and after the COVID-19 pandemic: an assessment using the EFIC_AD tool, developed by the Sociedad Española de Patología Digestiva (SEPD)

INTRODUCTION

the COVID-19 pandemic had a strong impact on the healthcare model. The Sociedad Española de Patología Digestiva (SEPD) offered gastroenterology care units (UAAD) an instrument (EFIC_AD) to record and analyze their efficacy and efficiency. Thus, the impact of the pandemic on the activity of UAAD was assessed.

METHODS

A descriptive study, based on the EFIC_AD registry for the period 2019-2021, of activity regarding admissions, clinic visits, and endoscopic as well as non-endoscopic tests, and endoscopy room performance.

RESULTS

data were collected from up to 42 hospitals (22 with ≥ 500 beds). Overall, activity during 2020 compared to 2019 decreased by 12.30 % for admissions and 40 % for pH-metries (16.70 % for new clinic visits; 14.34 % for referrals from primary care; 24.70 % for gastroscopies; 32.50 % for colonoscopies; 31.00 % for endoscopic ultrasounds; 18.20 % for endoscopic retrograde cholangiopancreatography (ERCPs); 38.00 % for manometries; 23.60 % for abdominal ultrasounds; 36.17 % for liver transient elastographies [Fibroscan®]). The levels achieved during 2019 were not fully recovered during 2021 except for digestive motility studies, and virtually for endoscopy room performance rate (88.15 % in 2019; 67.77 % in 2020; 85.93 % in 2021).

CONCLUSIONS

during 2020 the COVID-19 pandemic led to a markedly decreased in specific activities at UAAD, which was not fully recovered in 2021 despite endoscopy room performance return to normal.

Diet and microbiome in the beginning of the sequence of gut inflammation

Inflammatory bowel disease (IBD) is a chronic inflammatory condition of the gastrointestinal tract due, at least partially, to an aberrant and excessive mucosal immune response to gut bacteria in genetically-predisposed individuals under certain environmental factors. The incidence of IBD is rising in western and newly industrialized countries, paralleling the increase of westernized dietary patterns, through new antigens, epithelial function and permeability, epigenetic mechanisms (e.g., DNA methylation), and alteration of the gut microbiome. Alteration in the composition and functionality of the gut microbiome (including bacteria, viruses and fungi) seems to be a nuclear pathogenic factor. The microbiome itself is dynamic, and the changes in food quality, dietary habits, living conditions and hygiene of these western societies, could interact in a complex manner as modulators of dysbiosis, thereby influencing the activation of immune cells' promoting inflammation. The microbiome produces diverse small molecules via several metabolic ways, with the fiber-derived short-chain fatty acids (i.e., butyrate) as main elements and having anti-inflammatory effects. These metabolites and some micronutrients of the diet (i.e., vitamins, folic acid, beta carotene and trace elements) are regulators of innate and adaptive intestinal immune homeostasis. An excessive and unhealthy consumption of sugar, animal fat and a low-vegetable and -fiber diet are risk factors for IBD appearance. Furthermore, metabolism of nutrients in intestinal epithelium and in gut microbiota is altered by inflammation, changing the demand for nutrients needed for homeostasis. This role of food and a reduced gut microbial diversity in causing IBD might also have a prophylactic or therapeutic role for IBD. The relationship between dietary intake, symptoms, and bowel inflammation could lead to dietary and lifestyle recommendations, including diets with abundant fruits, vegetables, olive oil and oily fish, which have anti-inflammatory effects and could prevent dysbiosis and IBD. Dietary modulation and appropriate exclusion diets might be a new complementary management for treatment at disease flares and in refractory patients, even reducing complications, hospitalizations and surgery, through modifying the luminal intestinal environment.

Predictors: How to Approach the Individualization of Treatment

The "big data" in inflammatory bowel disease opens a route of detection of predictors that can determine the prognosis of each patient and allow the individualized selection of more efficient and safe therapeutic strategies. Immune biomarkers are a promising field to explore thoroughly.

Rapidity of clinical response to adalimumab and improvement of quality of life in luminal Crohn's disease: RAPIDA study

OBJECTIVE

No studies evaluating the rapidity of response to biological therapies are available for Crohn's disease (CD). The aim of this study was to evaluate rapidity of onset of clinical response and impact on quality of life (QoL) of adalimumab therapy in adult anti-TNF-naïve patients with moderately-to-severely active CD.

PATIENTS AND METHODS

RAPIDA was an open-label, single-arm, prospective, multicenter clinical trial. Adult patients with moderately-to-severely active luminal CD, anti-TNF-naïve, and unresponsive to conventional therapy were treated with adalimumab. Clinical disease activity, QoL and inflammatory biomarkers were measured at day 4, and weeks 1, 2, 4, and 12 after treatment initiation.

RESULTS

Eighty-six patients were included in the intention-to-treat (ITT) analyses. Clinical disease activity was reduced from a median of 9.0 points to 6.0 points at day 4. Clinical response (≥ 3-point reduction in the Harvey-Bradshaw Index, HBI) was achieved by 61.6% (d4) and 75.6% (w1) of patients in the ITT population (median 2.5 days) and with non-responder imputation (NRI), by 55.8% and 53.4%, respectively. The proportion of patients in clinical remission (HBI<5) at weeks 2 and 4 in the ITT population was 54.7% and 62.8%, respectively (median 7.0 days), and 38.4% and 45.3% in the NRI population. All QoL scores significantly improved and inflammatory biomarkers significantly decreased from day 4 onwards (p<0.0001).

CONCLUSION

Rapid clinical response and remission, improvement in QoL and fatigue, and a reduction of inflammatory biomarkers were achieved with adalimumab as early as day 4 in adult anti-TNF-naïve patients with moderately-to-severely active CD.

Predictive factors of clinical response to treatment with anti-TNF agents in ulcerative colitis: what have we learned from our patients?

INTRODUCTION

inhibitors of tumor necrosis factor alpha (anti-TNFs) are effective drugs for the treatment of moderate-to-severe ulcerative colitis (UC). However, many patients do not respond or lose therapeutic response during follow-up.

OBJECTIVES

to analyze the determining factors of clinical response to anti-TNFs in UC.

METHODS

a multicenter retrospective study was performed in 79 patients with UC who started treatment with anti-TNFs between 2009 and 2015. The primary endpoint was clinical remission (pMayo index ≤ 1) at 12 months. Furthermore, remission and clinical response (final pMayo score ≤ 3) and corticoids discontinuation were assessed at three, six and 12 months. An analysis was performed to identify variables predictive of clinical response.

RESULTS

at 12 months, remission and clinical response were seen in 59.2 % and 77.8 % of patients, respectively. Corticoids could be discontinued in 82.4 % of patients. At 12 months, corticoids discontinuation (< 3 months) (OR 0.06; 95 % CI: 0.01-0.24) and clinical response at six months (OR 0.008; 95 % CI: 0.001-0.053) were independent factors predictive of clinical remission.

CONCLUSION

in patients with active UC on anti-TNFs, corticoid discontinuation within three months and clinical response at six months after treatment onset are predictive of clinical disease remission.

Sleep Quality, Quality of Life, and Patient-Reported Outcomes

Measuring health outcomes through patient-reported outcomes is a feasible scenario in the short term, more human, and more linked to the situation that the patient cares about, overcoming limitations of the classic activity scores.

EpidemIBD: rationale and design of a large-scale epidemiological study of inflammatory bowel disease in Spain

BACKGROUND

Inflammatory bowel disease (IBD) is associated with a considerable burden to the patient and society. However, current data on IBD incidence and burden are limited because of the paucity of nationwide epidemiological studies, heterogeneous designs, and a low number of participating centers and sample size. The EpidemIBD study is a large-scale investigation to provide an accurate assessment of the incidence of IBD in Spain, as well as treatment patterns and outcomes.

METHODS

This multicenter, population-based incidence cohort study included patients aged >18 years with IBD (Crohn's disease, ulcerative colitis, or unclassified IBD) diagnosed during 2017 in 108 hospitals in Spain, covering 50% of the Spanish population. Each participating patient will attend 10 clinic visits during 5 years of follow up. Demographic data, IBD characteristics and family history, complications, treatments, surgeries, and hospital admissions will be recorded.

RESULTS

The EpidemIBD study is the first large-scale nationwide study to investigate the incidence of IBD in Spain. Enrollment is now completed and 3627 patients are currently being followed up.

CONCLUSIONS

The study has been designed to overcome many of the limitations of previous European studies into IBD incidence by prospectively recruiting a large number of patients from all regions of Spain. In addition to epidemiological information about the burden of IBD, the 5-year follow-up period will also provide information on treatment patterns, and the natural history and financial burden of IBD.

Quality of life during one year of postoperative prophylactic drug therapy after intestinal resection in Crohn's patients: Results of the APPRECIA trial

BACKGROUND

In APPRECIA trial, Crohn's disease (CD) patients undergoing intestinal resection were randomized to postoperative adalimumab (ADA) or azathioprine (AZA).

AIMS

To evaluate health-related quality of life (HRQoL) in APPRECIA trial.

METHODS

HRQoL was evaluated using disease-specific shortened Spanish version of the IBDQ (SIBDQ-9) and generic European Quality of Life-5 Dimensions (EQ-5D) questionnaires, completed at baseline and at weeks 24 and 52.

RESULTS

Sixty-one patients (37 ADA and 24 AZA) had evaluable data for HRQoL. Patients treated with ADA or AZA had significant improvement from baseline to weeks 24 and 52 in SIBDQ-9 and EQ-5D (p < 0.001 and p ≤ 0.006 for all comparisons, respectively). There were no differences between treatment arms in mean change in SIBDQ-9 and EQ-5D at weeks 24 and 52 vs baseline. Only patients without endoscopic recurrence had significant improvement in SIBDQ-9 (p < 0.001) and EQ-5D (p < 0.001) at week 52. At week 52, there was a high to moderate negative correlation between CDAI score with SIBDQ-9 score (Pearson's r: -0.768) and with EQ-5D index (r: -0.644).

CONCLUSION

HRQoL improved after intestinal resection in CD, irrespective of the postoperative therapy used (ADA or AZA). Outcomes in HRQoL were associated with prevention of endoscopic recurrence, since improvements in HRQoL were only significant in patients with endoscopic remission at 1 year.

The Harvey-Bradshaw Index Adapted to a Mobile Application Compared with In-Clinic Assessment: The MediCrohn Study

Objectives: Mobile apps are useful tools in e-health and self-management strategies in disease monitoring. We evaluated the Harvey–Bradshaw index (HBI) mobile app self-administered by the patient to see if its results agreed with HBI in-clinic assessed by a physician.

Methods: Patients were enrolled in a 4-month prospective study with clinical assessments at months 1 and 4. Patients completed mobile app HBI and within 48 h, HBI was performed by a physician (gold standard). HBI scores characterized Crohn's disease (CD) as remission <5 or active ≥5. We determined agreement per item and total HBI score and intraclass correlation coefficients (ICCs). Bland–Altman plot was performed. HBI changes in disease activity from month 1 to month 4 were determined.

Results: A total of 219 patients were enrolled. All scheduled assessments (385 pairs of the HBI questionnaire) showed a high percentage of agreement for remission/activity (92.4%, κ = 0.796), positive predictive value (PPV) for remission of 98.2%, and negative predictive value of 76.7%. High agreement was also found at month 1 (93.15%, κ = 0.82) and month 4 (91.5%, κ = 0.75). Bland–Altman plot was more uniform when the HBI mean values were <5 (remission). ICC values were 0.82, 0.897, and 0.879 in all scheduled assessments, 1 and 4 months, respectively.

Conclusions: We found a high percentage of agreement between patients' self-administered mobile app HBI and in-clinic physician assessment to detect CD activity with a remarkably high PPV for remission. The mobile app HBI might allow a strict control of inflammation by remote monitoring and flexible follow-up of CD patients. Reduction of sanitary costs could be possible.

Serial Tuberculin Skin Tests Improve the Detection of Latent Tuberculosis Infection in Patients With Inflammatory Bowel Disease

AIM

To assess the likelihood of detecting latent tuberculosis infection [LTBI] by the positive conversion of a serial tuberculin skin test [TST] at 1 year in inflammatory bowel disease [IBD] patients with negative baseline two-step TST.

METHODS

In this multicentre prospective cohort study, we evaluated rate and predictors of conversion of TST at 1 year in patients with negative baseline TST. We also evaluated management of patients who had a positive TST at baseline or a conversion at 1 year. In all patients we assessed TB cases occurring during follow-up.

RESULTS

Of the 192 IBD patients receiving anti-tumour necrosis factor [TNF] and 220 IBD controls not receiving anti-TNF, 35 [8.5%, 95% CI 5.7-11.3] had positive conversion (median TST induration 13 mm, interquartile range [IQR] 9-16). Ten anti-TNF cohort patients [5.2%, 95% CI 2.5-9.5] versus 25 controls [11.4%, 95% CI 7.5-16.3] had TST conversion [p = 0.029]. In multivariate analysis, conversion was associated with smoking habit (odds ratio [OR] 2.19, 95% CI 1.08-3.97; p = 0.028). Anti-TNF-treated patients had a lower conversion rate [OR 0.41, 95% CI 0.20-0.83; p = 0.013]. The likelihood of conversion correlates with fewer immunosuppressive therapies between baseline TST and TST at 1 year [p = 0.042]. One case of active TB [isoniazid-resistant strain] occurred in a patient with positive baseline TST receiving anti-TNF [0.05 events/100 patient-years].

CONCLUSIONS

Serial TST at 1 year can detect LTBI in IBD patients receiving anti-TNF therapy with negative baseline TST. Serial TST seems to be advisable to reduce the risk of TB cases associated with inability to detect LTBI in pre-treatment screening.

Clinical status, quality of life, and work productivity in Crohn's disease patients after one year of treatment with adalimumab

OBJECTIVE

Clinical trials have shown the efficacy of adalimumab in Crohn's disease, but the outcome in regular practice remains unknown. The aim of the study was to examine clinical status, quality of life, and work productivity of Crohn's disease patients receiving adalimumab for one year in the context of usual clinical practice.

MATERIAL AND METHODS

This was a prospective, observational study with a one-year follow-up. After baseline, Crohn's disease patients were evaluated at 1, 3, 6, 9, and 12 months after starting treatment with adalimumab. Outcome variables included: clinical status (measured with CDAI), quality of life (measured with EuroQoL-5D and IBDQ), and work productivity (measured with WPAI questionnaire). These outcome variables were compared using the Student's t test or Wilcoxon test for paired comparison data according to the data distribution. Statistical significance was set at two-sided p < 0.05.

RESULTS

The sample was composed of 126 patients (age [mean] 39.1 ± [standard deviation] 13.8 years; 51% male). Significant changes were observed during the follow-up period: CDAI decreased from [median] 194 ([25-75 percentiles] 121-269) to 48.2 (10.1-122.0) (p < 0.05); the EuroQoL-5D increased from 0.735 (0.633-0.790) to 0.797 (0.726-1.000) (p < 0.05); the EuroQoL-5D visual analogue scale increased from 50.0 (40-70) to 80.0 (60-90); (p < 0.05) and the IBDQ increased from 56.7 (51.6-61.5) to 67.5 (60.1-73.6) (p < 0.05). The total work productivity impact decreased from 53% to 24% (p < 0.05).

CONCLUSIONS

In regular practice, adalimumab is clinically effective in the treatment of Crohn's disease patients and results in a significant improvement in quality of life and work productivity.

Adalimumab vs Azathioprine in the Prevention of Postoperative Crohn's Disease Recurrence. A GETECCU Randomised Trial

BACKGROUND AND AIMS

Postoperative recurrence of Crohn's disease [POR-CD] is almost certain if no prophylaxis is administered. Evidence for optimal treatment is lacking. Our aim was to compare the efficacy of adalimumab [ADA] and azathioprine [AZA] in this setting.

METHODS

We performed a phase 3, 52-week, multicentre, randomised, superiority study [APPRECIA], in which patients with ileocolonic resection were randomised either to ADA 160-80-40 mg subcutaneously [SC] or AZA 2.5 mg/kg/day, both associated with metronidazole. The primary endpoint was endoscopic recurrence at 1 year [Rutgeerts i2b, i3, i4], as evaluated by a blinded central reader.

RESULTS

We recruited 91 patients [median age 35.0 years, disease duration 6.0 years, 23.8% smokers, 7.1% previous resections]. The study drugs were administered to 84 patients. Treatment was discontinued owing to adverse events in 11 patients [13.1%]. Discontinuation was significantly less frequent in the ADA [4.4%] than in the AZA group [23.2%] (dif.: 18.6% [95% CI 4.1-33.2], p = 0.011). According to the intention-to-treat analysis, therapy failed in 23/39 patients in the AZA group [59%] and 19/45 patients in the ADA group [42.2%] [p = 0.12]. In the per-protocol analysis [61 patients with centrally evaluable images], recurrence was recorded in 8/24 [33.3%] patients in the AZA and 11/37 [29.7%] in the ADA group [p = 0.76]. No statistically significant differences between the groups were found for recurrence in magnetic resonance images, biological markers of activity, surgical procedures, or hospital admissions.

CONCLUSIONS

ADA has not demonstrated a better efficacy than AZA [both associated with metronidazole] for prophylaxis of POR-CD in an unselected population, although tolerance to ADA is significantly better. ClinicalTrials.gov NCT01564823.

Long-term control of refractory hemorrhagic radiation proctitis with ozone therapy

CONTEXT

Persistent or severe hemorrhagic radiation proctitis (HRP) has limited therapeutic options.

OBJECTIVES

To describe our experience with ozone therapy (O3T) in the management of refractory HRP.

METHODS

Patients (n=17; median age 69 years [range 42-80 years]) previously irradiated for prostate or uterine cancer and suffering persistent or severe HRP without response to conventional treatment were enrolled to receive an O3/O2 gas mixture via rectal insufflations and topical application of ozonized oil. Most of the patients (83%) had Grade 3 or Grade 4 toxicity. Median follow-up post-O3T was 40 months (range 3-56 months).

RESULTS

Endoscopic treatments required were: 43 (median 1; range 0-10) pre-O3T; 17 (median 0; range 0-8; P=0.063) during O3T; and five (median 0; range 0-2; P=0.008) during follow-up. Hemoglobin levels were 10.35g/dL (7-14g/dL) pre-O3T and 13g/dL (9-15g/dL) (P=0.001) post-O3T. Median toxicity grades were 3 (range 2-4) pre-O3T, 1 (range 0-2; P<0.001) at the end of O3T, and 0 (range 0-1; P<0.001) at the last follow-up.

CONCLUSION

Persistent advanced HRP was significantly improved with O3T. The addition of O3T can be useful as a complementary treatment in the long-term management of HRP and, as such, merits further evaluation.

Usefulness of oral beclometasone dipropionate in the treatment of active ulcerative colitis in clinical practice: the RECLICU Study

BACKGROUND

Beclometasone dipropionate (BDP) is a relatively new topically acting oral steroid to treat mild to moderately active ulcerative colitis (UC). We estimate that 20,000 patients have received oral BDP in Spain in the last two years. Our aim was to evaluate the efficacy and safety of oral BDP in clinical practice.

METHODS

Retrospective and multicenter study that included 434 patients with active UC treated with BDP. The partial Mayo Clinic score (pMS, 0-9) was used to measure disease activity. Remission was defined as post-treatment pMS of 0 or 1; response as a decrease in pMS of 3 points or 2 points and >30%, and failure as lack of remission or response.

RESULTS

BDP dose was 5 mg/day in 88% of patients and mean treatment duration was 6.2 weeks. BDP achieved remission in 44.4%, response in 22.3% and failed in 33.2% of patients. Mean pMS decreased from 4.9 ± 1.3 to 2.4 ± 2.3 (p<0.0001). Remission rate was higher in mild and moderate than in severe UC (p<0.043) and tended to be higher in left-sided and extensive UC than in proctitis (p<0.06). Failure was less frequent in patients treated for >4 weeks (p<0.02). Mild adverse events were reported in 7.6% of patients.

CONCLUSION

BDP induces response or remission in two thirds of active UC patients, with a good safety profile. Patients with mild to moderate, left-sided or extensive UC, receiving BDP for more than 4 weeks are most likely to benefit from this treatment.

Efficacy and safety of short-term adalimumab treatment in patients with active Crohn's disease who lost response or showed intolerance to infliximab: a prospective, open-label, multicentre trial

BACKGROUND

The use of tumour necrosis factor antagonists has changed the therapeutic approach to Crohn's disease.

AIM

To determine response and remission rates associated with the 4-week induction phase of adalimumab treatment in patients with luminal and/or fistulizing Crohn's disease, who have lost response to or become intolerant of infliximab.

METHODS

In this multicentre, prospective, open-label, observational, 52-week study, 50 adults received an induction dose of adalimumab (160 mg at baseline followed by 80 mg at week 2).

RESULTS

Of the 36 patients with luminal Crohn's disease, 83% achieved clinical response [> or =70-point reduction in the Crohn's Disease Activity Index (CDAI) score] and 42% achieved clinical remission (CDAI score <150) at week 4. Of the 22 patients with fistulizing disease, five (23%) experienced fistula remission (complete closure of all fistulas that were draining at baseline), and nine (41%) experienced fistula improvement (> or =50% decrease in the number of fistulas that were draining at baseline) at week 4. Of the 19 adverse events, most [13 (68%)] were mild, and no serious or infectious adverse events occurred.

CONCLUSIONS

Adalimumab may be an effective alternative in patients with luminal and/or fistulizing Crohn's disease who have lost response to or become intolerant of infliximab.

Role of metallothioneins in peripheral nerve function and regeneration

The physiological role of the metallothionein (MT) family of proteins during peripheral nerve injury and regeneration was examined in Mt1+ 2 and Mt3 knockout (KO) mice. To this end, the right sciatic nerve was crushed, and the regeneration distance was evaluated by the pinch test 2-7 days postlesion (dpl) and electrophysiologically at 14 dpl. The quality of the regeneration was assessed by light microscopy and immunohistochemical methods. The results show that the regeneration distance was greater in the Mt3 KO than in the Mt1+ 2 KO mice, whereas control mice showed intermediate values. Moreover, the number of regenerating axons in the distal tibial nerve was significantly higher in Mt3KO mice than in the other two strains at 14 dpl. Immunoreactive profiles to protein gene product 9.5 were present in the epidermis and the sweat glands of the plantar skin of the hindpaw of the Mt3 KO group. The improved regeneration observed with the Mt3 KO mice was confirmed by compound nerve action potentials that were recorded from digital nerves at 14 dpl only in this group. We conclude that Mt3 normally inhibits peripheral nerve regeneration.

Engineering an artificial nerve graft for the repair of severe nerve injuries

Nerve repair with tubes has a limit to regeneration depending upon the length of the gap. The characteristics of the guide, in terms of permeability, durability and adhesiveness, also influence regeneration. Considering the importance of the cellular component in regeneration, the development of artificial grafts, composed of a biocompatible nerve guide filled with a neurotropic matrix and seeded with Schwann cells (SCs), is an interesting option to enhance nerve regeneration and provide an alternative to the classical autologous nerve graft. We evaluated the ability of SCs transplanted into a nerve guide to improve regeneration after sciatic nerve resection, leaving a 6-mm gap, in the mouse. Syngeneic, isogeneic and autologous SCs were suspended in Matrigel and seeded in resorbable guides, and compared to acellular guides and to nerve autografts. The immunogenicity of the transplanted SCs clearly influenced the outcome. Transplants of autologous SCs resulted in only slightly lower levels of reinnervation than autografts, but higher recovery and number of regenerated axons than transplants of isologous and syngeneic SCs, and than acellular guides. Thus, by combined developments on nerve guides, extracellular matrix components and cell transplantation, an artificial graft has been designed that allows axonal regeneration across long gaps to levels comparable with an autograft.

Effects of FK506 on nerve regeneration and reinnervation after graft or tube repair of long nerve gaps

We compared the effects of FK506 administration on regeneration and reinnervation after sciatic nerve resection and repair with an autologous graft or with a silicone tube leaving a 6-mm gap in the mouse. Functional reinnervation was assessed by noninvasive methods to determine recovery of motor, sensory, and sweating functions in the hindpaw over 4 months after operation. Morphometric analysis of the regenerated nerves was performed at the end of follow-up. The nerve graft allowed for faster and higher levels of reinnervation in the four functions tested than silicone tube repair. Treatment with FK506 (for the first 9 weeks only) resulted in a slight, although not significant, improvement of the onset of reinnervation and of the maximal degree of recovery achieved after autografting. The recovery of pain sensibility and of the compound nerve action potentials in the digital nerves, which directly depend on axonal regeneration, showed better progression with FK506 than reinnervation of muscles and sweat glands, which require reestablishment of synaptic contacts with target cells. The myelinated fibers in the regenerated nerve showed a more mature appearance in the FK506-treated rats. However, FK506 showed a marginal effect in situations in which regeneration was limited, as in a silicone tube bridging a 6-mm gap in the mouse sciatic nerve. In conclusion, treatment with FK506 improved the rate of functional recovery after nerve resection and autograft repair.

Influence of aging on peripheral nerve function and regeneration

Aging deeply influences several morphologic and functional features of the peripheral nervous system (PNS). Morphologic studies have reported a loss of myelinated and unmyelinated nerve fibers in elderly subjects, and several abnormalities involving myelinated fibers, such as demyelination, remyelination and myelin balloon figures. The deterioration of myelin sheaths during aging may be due to a decrease in the expression of the major myelin proteins (P0, PMP22, MBP). Axonal atrophy, frequently seen in aged nerves, may be explained by a reduction in the expression and axonal transport of cytoskeletal proteins in the peripheral nerve. Aging also affects functional and electrophysiologic properties of the PNS, including a decline in nerve conduction velocity, muscle strength, sensory discrimination, autonomic responses, and endoneurial blood flow. The age-related decline in nerve regeneration after injury may be attributed to changes in neuronal, axonal, Schwann cell and macrophage responses. After injury, Wallerian degeneration is delayed in aged animals, with myelin remnants accumulated in the macrophages being larger than in young animals. The interaction between Schwann cells and regenerative axons takes longer, and the amount of trophic and tropic factors secreted by reactive Schwann cells and target organs are lower in older subjects than they are in younger subjects. The rate of axonal regeneration becomes slower and the density of regenerating axons decrease in aged animals. Aging also determines a reduction in terminal and collateral sprouting of regenerated fibers, further limiting the capabilities for target reinnervation and functional restitution. These age-related changes are not linearly progressive with age; the capabilities for axonal regeneration and reinnervation are maintained throughout life, but tend to be delayed and less effective with aging.

Peripheral nerve regeneration through bioresorbable and durable nerve guides

We compared reinnervation of target organs after sciatic nerve resection and repair by tubulization with biodurable tubes of silicone and teflon, or bioresorbable nerve guides of collagen and poly(L-lactide-co-6-caprolactone) (PLC) leaving a 6 mm gap in different groups of mice. All tubes were of 1 mm inside diameter and thin-walled (50 to 250 microm). Functional reinnervation was assessed by noninvasive methods to determine recovery of sweating, sensory and motor functions in the hindpaw repeatedly during 5 months postoperation. PLC guides allowed faster and higher levels of reinnervation for the four functions tested than collagen and silicone tubes, while teflon tubes gave the lowest levels of recovery. Regenerative reinnervation by thin nociceptive and sudomotor fibers was higher than by large sensory and alphamotor fibers in all groups. Resorbable tubes promoted regeneration in a higher proportion of mice than durable tubes. In cases with effective regeneration the nerve cable was multifascicular, with mild to moderate mononuclear cell infiltrates and a thin newly formed perineurium. The number of myelinated fibers was higher in PLC and silicone tubes than in collagen and teflon tubes. There was only minimal inflammatory reaction within the remnants of collagen tubes, but not in the other materials. PLC tubes of slow reabsorption rate seem useful for repairing long gaps in injured nerves.

Polyimide cuff electrodes for peripheral nerve stimulation

This paper describes a new tripolar spiral cuff electrode, composed of a thin (10 microm) and flexible polyimide insulating carrier and three circumneural platinum electrodes, suitable for stimulation of peripheral nerves. The cuffs were implanted around the sciatic nerve of two groups of ten rats each, one in which the polyimide ribbon was attached to a plastic connector to characterize the in vivo stimulating properties of the electrode, and one without a connector for testing possible mechanical nerve damage by means of functional and histological methods. The polyimide cuff electrodes induced only a very mild foreign body reaction and did not change the nerve shape over a 2-6 month implantation period. There were no changes in the motor and sensory nerve conduction tests, nociceptive responses and walking track pattern over follow-up, and no morphological evidence of axonal loss or demyelination, except in one case with partial demyelination of some large fibers after 6 months. By delivering single electrical pulses through the cuff electrodes graded recruitment curves of alpha-motor nerve fibers were obtained. Recruitment of all motor units was achieved with a mean charge density lower than 4 microC/cm(2) for a pulse width of 50 micros at the time of implantation as well as 45 days thereafter. These data indicate that the polyimide cuff electrode is a stable stimulating device, with physical properties and dimensions that avoid nerve compression or activity-induced axonal damage.

Nerve guides seeded with autologous schwann cells improve nerve regeneration

This study evaluates the ability of Schwann cells (SCs) transplanted into a nerve guide to improve regeneration and reinnervation after sciatic nerve resection and repair, leaving a 6-mm gap, in the mouse. SCs were isolated from predegenerated adult sciatic nerves and expanded in culture using a chemically defined medium. Syngeneic, isogeneic, and autologous SCs were suspended in Matrigel and seeded in resorbable, permeable poly(l-lactide-co-epsilon-caprolactone) guides at 150,000 cells/tube. Guides containing SCs were compared to guides filled with Matrigel alone and with peroneal nerve autografts. Functional reinnervation was assessed by noninvasive methods to determine recovery of sweating, nociceptive, sensory, and motor functions in the hindpaw during 4 months postoperation. Morphological analysis of the regenerated nerves was performed at the end of follow-up. The group with an autograft achieved faster and higher levels of reinnervation and higher number of regenerated myelinated fibers than groups repaired by tubulization. The immunogenicity of transplanted SCs influenced the outcome of nerve regeneration. Transplants of autologous SCs resulted in slightly lower levels of reinnervation than autografts, but higher recovery and number of regenerated fibers reaching the distal nerve than transplants of isologous and syngeneic SCs, although most of the differences were not statistically significant. Syngeneic SCs did not improve regeneration with respect to acellular guides. Prelabeled transplanted SCs were found to survive into the guide 1-3 months after implantation, to a larger number when they were autologous than syngeneic. Cellular prostheses composed of a resorbable guide seeded with autologous SCs appear as an alternative for repairing long gaps in injured nerves, approaching the success of autografts.

Morphometric and ultrastructural changes with ageing in mouse peripheral nerve

Qualitative and quantitative information is reported on the morphological changes that occur in nerve fibres and nonneuronal cells of peripheral nerve during the lifetime of the mouse. Tibial nerves of mice aged 6-33 mo were studied. With ageing, collagen accumulates in the perineurium and lipid droplets in the perineurial cells. Macrophages and mast cells increase in number, and onion bulbs and collagen pockets are frequently present. Schwann cells associated with myelinated fibres (MF) slightly decrease in number in parallel with an increase of the internodal length from 6 to 12 mo, but increase in older nerves when demyelination and remyelination are common. The unmyelinated axon to myelinated fibre (UA/MF) ratio was about 2 until 12 mo, decreasing to 1.6 by 27 mo. In older mice, the loss of nerve fibres involves UA (50% loss of 27-33 mo cf. 6 mo) more markedly than MF (35%). In aged nerves wide incisures and infolded or outfolded myelin loops are frequent, resulting in an increased irregularity in the morphology of fibres along the internodes. In the mouse there is an adult time period, 12-20 mo, during which several features of degeneration progressively appear, and an ageing period from 20 mo upwards when the nerve suffers a general disorganisation and marked fibre loss.

Magnetically aligned collagen gel filling a collagen nerve guide improves peripheral nerve regeneration

Bioresorbable collagen nerve guides filled with either magnetically aligned type I collagen gel or control collagen gel were implanted into 4- or 6-mm surgical gaps created in the sciatic nerve of mice and explanted 30 and 60 days postoperation (dpo) for histological and immunohistochemical evaluation. The hypothesis was that contact guidance of regenerating axons and/or invading nonneuronal cells to the longitudinally aligned collagen fibrils would improve nerve regeneration. The criterion for regeneration was observation of regenerating myelinated fibers distal to the nerve guide. Consistent with previous studies showing poor regeneration in 6-mm gaps at 60 dpo with entubulation repair, only one of six mice exhibited regeneration with control collagen gel. In contrast, four of four mice exhibited regeneration with magnetically aligned collagen gel, including the appearance of nerve fascicle formation. The numbers of myelinated fibers were less than the uninjured nerve in all groups, however, which may have been due to rapid resorption of the nerve guides. An attempt to increase the stability of the collagen gel, and thereby the directional information presented by the aligned collagen fibrils, by crosslinking the collagen with ribose before implantation proved detrimental for regeneration.

Olfactory bulb ensheathing cells enhance peripheral nerve regeneration

Sciatic nerve resection leaving a 15 mm gap could not be repaired by bridging the stumps with a silicone tube prefilled with a laminin gel. However, when purified olfactory ensheathing cells (EC) were added to the gel filling the tube, successful axonal regeneration was observed in 50% of rats. With 12 mm gaps, regeneration occurred in 79% of rats with transplanted EC compared with 60% of those receiving collagen gel alone. Therefore, ECs help repair severe peripheral nerve injuries, in addition to their ability to promote axonal regeneration within the central nervous system.

Physiological and immunohistochemical characterization of cisplatin-induced neuropathy in mice

We investigated the neuropathic effects of cisplatin in two groups of mice treated with 5 or 10 mg/kg/week of cisplatin for 7 or 8 weeks. Peripheral nerve functions were evaluated by sweat imprints, and electrophysiological, rotarod, and nociceptive tests. Protein gene product 9.5 (PGP), calcitonin gene-related peptide (CGRP), and vasoactive intestinal peptide (VIP) were immunohistochemically localized in footpads. Tibial nerves were analyzed morphometrically. Functional deficits developed progressively with higher cumulative doses, more markedly in mice treated with high than in those with low doses. From cumulative doses of 10 mg/kg, significant declines in sensory nerve conduction velocity and sudomotor responses were found, whereas motor and nociceptive functions were involved later. There were no morphometrical changes in tibial nerves. A marked decrease of CGRP- and VIP-immunoreactive nerves occurred in samples from treated mice, whereas PGP-labeled profiles decreased mildly at late stages. Impairment of the content of neuropeptides with neurosecretor role was detectable earlier than functional abnormalities. Immunohistochemical analysis of skin biopsies offers a useful diagnostic tool for peripheral neuropathies.