Oral supplementation with fish cartilage hydrolysate in an adult population suffering from knee pain and function discomfort: results from an innovative approach combining an exploratory clinical study and an ex vivo clinical investigation

BACKGROUND

Aging is frequently associated with impairments of the musculoskeletal system and many elderly people experience joint discomfort or pain which might reduce their ability to move and consequently alter their quality of life. A beneficial effect of fish cartilage hydrolysate (FCH) on pain and joint function has recently been shown in an ACLT/pMMx osteoarthritis rat model.

METHODS

We therefore performed an exploratory, non-comparative, multi-centric clinical trial including 33 subjects with moderate knee joint discomfort and loss of functionality to investigate the efficacy of FCH on their algo-functional status. We further determined the potential health benefit of FCH in an original clinical ex vivo study investigating the role of FCH human metabolites on primary human chondrocytes.

RESULTS

FCH significantly improved knee pain and function, as assessed by the Knee injury and Osteoarthritis Outcome Score (KOOS). Moreover, FCH significantly reduced pain at rest and while walking, and patient global assessment (PGA), as assessed by the Visual Analogue Scale (VAS), and improved patients' quality of life (SF-36). FCH metabolites decreased the synthesis of catabolic factors (MMP-13) and pro-inflammatory mediators (NO, PGE2) and limited the inhibitory effect of IL-1β on the synthesis of cartilage matrix components (GAG and collagen).

CONCLUSIONS

Thus, these data provide insights on the mode of action of FCH in humans and contribute to explain how FCH may relieve pain and improve joint function in subjects with knee discomfort. Although these preliminary data need to be confirmed in a randomized controlled trial, they strongly support the potential health benefit of such an active ingredient.

TRIAL REGISTRATION

The study was registered on clinicaltrials.gov with the identifier NCT04420091 (09/06/2020).

NASAFYTOL® supplementation in adults hospitalized with COVID-19 infection: results from an exploratory open-label randomized controlled trial

Objectives

The effect and safety of Nasafytol^®, a food supplement combining curcumin, quercetin, and Vitamin D, on hospitalized COVID-19-positive patients as support to standard of care were to be assessed.

Methods

This exploratory, open-label, randomized, controlled trial was carried out among hospitalized adults with COVID-19 infection. Participants were randomly assigned to receive Nasafytol^® or Fultium^® control. The improvement of the clinical condition and occurrence of (serious) adverse events were evaluated. The study was registered on clincaltrials.gov with the identifier NCT04844658.

Results

Twenty-five patients received Nasafytol^®, and 24 received Fultium^®. Demographic characteristics were well balanced between the groups. On day 14 (or at hospital leave if < 14 days), no difference was observed between groups regarding their clinical condition, fever, or the need of oxygen therapy. At day 7, however, 19 participants had been discharged from the hospital in the Nasafytol^® arm compared to 10 participants in the Fultium^® arm. No participants were transferred to the ICU or died in the Nasafytol^® arm, vs. 4 transfers and 1 death in the Fultium^® arm. The clinical condition of participants in the Nasafytol^® arm had improved, as evidenced by a decrease in the COVID-19 WHO score. Interestingly, five SAEs occurred with Fultium^®, while no SAE was observed with Nasafytol^®.

Conclusion

Supplementation with Nasafytol^®, in addition to standard-of-care treatment, led to a faster discharge from the hospital, improved clinical conditions of participants, and a reduced risk of serious outcomes, including transfer to the intensive care unit or death, in patients hospitalized with COVID-19.

Serum Levels of Coll2-1, a Specific Biomarker of Cartilage Degradation, Are Not Affected by Sampling Conditions, Circadian Rhythm, and Seasonality

OBJECTIVE

To assess intraindividual biological variability of serum cartilage specific biomarker Coll2-1 and define the best standardized conditions for blood sampling.

DESIGN

Blood samples were taken from 116 subjects with knee osteoarthritis (OA) at a single time point (PRODIGE study) and from 15 healthy subjects under various conditions, including fasting condition, sampling time and season, blood treatment, and type of blood collection tube (COVAR study). Type II collagen-specific biomarker Coll2-1 was directly measured in serum using an immunoassay.

RESULTS

There was no significant difference on Coll2-1 values between samples collected at any of the 5 sampling times or at any of the sampling days measured. None of the sampling parameters tested had a significant impact on Coll2-1 value (clotting time, clotting temperature and temperature of blood centrifugation, type of tube). On the contrary, differences were found in between subjects and between subjects with knee OA and healthy subjects.

CONCLUSION

Coll2-1 measurement is not affected by sampling specific conditions, circadian rhythm or seasons but was found elevated in subject with knee OA indicating that Coll2-1 serum variation is not linked to the study environment, but to cartilage degradation in OA. Coll2-1 assay is sufficiently robust for use in OA clinical trials.

FRI0653-HPR AN OLEUROPEIN-BASED DIETARY SUPPLEMENT IMPROVES JOINT FUNCTIONALITY IN OLDER PEOPLE WITH HIGH KNEE JOINT PAIN

Background:

OLE provides oleuropein the most prevalent phenolic component in olive leaves and has been shown to have potent anti-inflammatory and anti-oxidant effects potentially interesting for joint health (1).

Objectives:

The aim of this study was to investigate the effects of a 6-month intervention with an Olive Leaf Extract (OLE) standardized for oleuropein content on knee functionality and biomarkers of bone/cartilage metabolism and inflammation.

Methods:

The study was a randomized, double-blind, placebo-controlled, multi-centric trial of 124 subjects with mild knee pain or mobility issues. Subjects were randomized equally to receive twice a day one capsule of either maltodextrin (control treatment, CT) or 125-mg OLE (BonoliveTM, an Olive Leaf Extract containing 50 mg of Oleuropein) for 6 months. The co-primary endpoints were Knee injury and Osteoarthritis Outcome Score (KOOS) using a self-administered questionnaire and serum Coll2-1NO2 specific biomarker of cartilage degradation. The secondary endpoints were each of the five sub-scales of the KOOS questionnaire, Knee pain VAS score at rest and at walking, OARSI core set of performance-based tests and serum biomarkers (Coll2-1, MPO, CTX1, osteocalcin, PGE2 and Vplex cytokines assay in serum) and concentration of Oleuropein’s metabolites in urine.

Results:

Primary (global KOOS score, biomarker Coll2-1 NO2) and secondary endpoints (the five subscales of the KOOS score) improved time dependently in both groups. OLE treatment showed significantly elevated urinary oleuropein metabolites (oleuropein aglycone, hydroxytyrosol, homovanillyl alcohol and isomer of homovanillyl alcohol), and was well tolerated without significant differences in number of subjects with adverse events. At 6 months, OLE group showed a higher global KOOS score compared to placebo (treatment difference = 3.73; 95% CI = [-4.08;11.54]; p = 0.34), without significant changes of inflammatory and cartilage remodeling biomarkers. Subgroup analyses demonstrated a large and significant treatment effect of OLE in subjects with high walking pain at baseline (14.4; 95% CI = [1.19;27.63], p=0.03). This was observed at 6 months for the global KOOS score and each different subscale and for pain at walking (-23.07;95% CI = [-41.8;-4.2];p=0.02). These treatment effects at 6 months were significant for KOOS score as well as for the subscales Pain and QoL and the pain at walking.

Conclusion:

OLE was not effective on joint discomfort in people with low to moderate pain at baseline but significantly benefited subjects with high pain at treatment initiation. As oleuropein is well-tolerated, OLE can be used to relieve knee joint pain and enhance mobility in subjects with articular pain the most painful subjects.

References:

[1] Horcajada MN, Sanchez C, Membrez Scalfo F, Drion P, Comblain F, Taralla S, Donneau AF, Offord EA, Henrotin Y. Oleuropein or rutin consumption decreases the spontaneous development of osteoarthritis in the Hartley guinea pig. Osteoarthritis Cartilage. 2015 Jan;23(1):94-102

Disclosure of Interests:

Marie-Noelle Horcajada Employee of: nestlé, Maurice Beaumont Employee of: nestle, Nicolas Sauvageot Employee of: Nestlé, Laure Poquet Employee of: Nestlé, Madleen Saboudjian Employee of: Nestlé, Anne-Christine Hick Employee of: Artialis SA, Berenice Costes Employee of: Artialis SA, Laetitia Garcia Employee of: Artialis, Yves Henrotin Grant/research support from: HEEL, TILMAN

FRI0405 CARTILAGE BIOMARKERS S-COLL2-1 AND S-COLL2-1NO2 ARE HELPFUL IN IDENTIFYING KNEE OSTEOARTHRITIS PATIENTS AT RISK OF DISEASE WORSENING

Background:

Coll2-1 is a peptide of 9 amino acid located in the triple helix of type II collagen molecule reflecting cartilage degradation (1). Coll2-1NO2 is the nitrated form of Coll2-1 and considered as a biomarker of the inflammatory-related cartilage degradation (2). This peptide is involved in osteoarthritis physiopathology since it was demonstrated that Coll2-1 induced synovitis in rat.

Objectives:

To identify if biochemical markers s-Coll2-1 and s-Coll2-1NO2 are associated to knee osteoarthritis (OA), focusing on pain, function as well as structural features assessed by MRI in various knee compartments and to assess their ability at predicting knee OA worsening.

Methods:

116 subjects with knee OA were followed during one year with pain, function and MRI evaluation (PRODIGE study,NCT02070224). Type II collagen-specific biomarker Coll2-1 and its nitrated form Coll2-1NO2 were directly measured in serum using immunoassays at baseline and after three, six and twelve months follow-up.

Results:

sColl2-1 and sColl2-1NO2 were associated to several baseline knee features quantified with Whole-Organ Magnetic Resonance Imaging Score (WORMS). S-Coll2-1 was significantly correlated with bursitis (r=0.29, P<0.01), bone attrition (r=0.25, P=0.01), cysts (r=0.24, P=0.02) and cartilage (r=0.23, P=0.03) WORMS sub-scores for the whole joint as well as with the medial femorotibial joint sum score (r=0.26, P=0.01) and medial femorotibial joint cartilage (r=0.23, P=0.02). s-Coll2-1NO2 was correlated with WORMS total score (r=0.23, P=0.02), WORMS scores in the patellofemoral (r=0.23, P=0.02) and medial femorotibial compartments (r=0.21, P=0.03) and with osteophytes scores (r=0.27, P<0.01). Baseline s-Coll2-1NO2 was higher in subjects with a pain worsening (426.4 pg/mL [278.04-566.95]) as compared to non-progressors (306.84 [200.37-427.84]) over one year (AUC=0.655, P=0.015).

Conclusion:

Cartilage biomarkers s-Coll2-1 and s-Coll2-1NO2 are associated to several knee OA features quantified with WORMS scoring system on MRI. Serum values of Coll2-1NO2 are also associated to a worsening of target knee pain over one year. Coll2-1 and Coll2-1NO2, in association with other structural features, pain and function, could help at identifying OA phenotypes and patients at risk of OA worsening.

References:

[1]Mobasheri A, Lambert C, Henrotin Y. Coll2-1 and Coll2-1NO2 as exemplars of collagen extracellular matrix turnover - biomarkers to facilitate the treatment of osteoarthritis? Expert Rev Mol Diagn. 2019 Sep;19(9):803-812. doi: 10.1080/14737159.2019.1646641. Epub 2019 Sep 4.

[2]Lambert C, Borderie D, Dubuc JE, Rannou F, Henrotin Y. Type II collagen peptide Coll2-1 is an actor of synovitis. Osteoarthritis Cartilage. 2019 Nov;27(11):1680-1691. doi: 10.1016/j.joca.2019.07.009. Epub 2019 Jul 17.

Acknowledgments:

PRODIGE study (NCT02070224) was performed in the framework of a convention between the Walloon region and ARTIALIS SA. (convention n°6905).

Disclosure of Interests:

Yves Henrotin Grant/research support from: HEEL, TILMAN, Berenice Costes Employee of: Artialis SA, Michel Malaise: None declared, Damien Loeuille: None declared, Thierry Conrozier Consultant of: LABRHA, SANOFI, MEDAC, Yves Maugars: None declared, Franz Pelousse Shareholder of: Sodiray, Jean-Marc Lemaire Shareholder of: Sodiray, Thibault Helleputte Shareholder of: DNAlytics, Cedric Tits Employee of: DNAlytics, Elisabeth Cobraiville Employee of: Artialis SA, Sebastien Pirson Employee of: Artialis, Laetitia Garcia Employee of: Artialis, Alain Labasse Employee of: Artialis SA, Anne-Christine Hick Employee of: Artialis SA

The IL-10 homologue encoded by cyprinid herpesvirus 3 is essential neither for viral replication in vitro nor for virulence in vivo

Cyprinid herpesvirus 3 (CyHV-3), a member of the family Alloherpesviridae, is the causative agent of a lethal disease in common and koi carp. CyHV-3 ORF134 encodes an interleukin-10 (IL-10) homologue. The present study was devoted to this ORF. Transcriptomic analyses revealed that ORF134 is expressed as a spliced gene belonging to the early-late class. Proteomic analyses of CyHV-3 infected cell supernatant demonstrated that the ORF134 expression product is one of the most abundant proteins of the CyHV-3 secretome. To investigate the role of ORF134 in viral replication in vitro and in virulence in vivo, a deleted strain and a derived revertant strain were produced using BAC cloning technologies. The recombinant ORF134 deleted strain replicated in vitro comparably to the parental and the revertant strains. Infection of fish by immersion in water containing the virus induced comparable CyHV-3 disease for the three virus genotypes tested (wild type, deleted and revertant). Quantification of viral DNA by real time TaqMan PCR (in the gills and the kidney) and analysis of carp cytokine expression (in the spleen) by RT-qPCR at different times post-infection did not revealed any significant difference between the groups of fish infected with the three virus genotypes. Similarly, histological examination of the gills and the kidney of infected fish revealed no significant differences between fish infected with ORF134 deleted virus versus fish infected with the control parental or revertant strains. All together, the results of the present study demonstrate that the IL-10 homologue encoded by CyHV-3 is essential neither for viral replication in vitro nor for virulence in common carp.

Skin mucus of Cyprinus carpio inhibits cyprinid herpesvirus 3 binding to epidermal cells

Cyprinid herpesvirus 3 (CyHV-3) is the aetiological agent of a mortal and highly contagious disease in common and koi carp. The skin is the major portal of entry of CyHV-3 in carp after immersion in water containing the virus. In the present study, we used in vivo bioluminescence imaging to investigate the effect of skin mucus removal and skin epidermis lesion on CyHV-3 entry. Physical treatments inducing removal of the mucus up to complete erosion of the epidermis were applied on a defined area of carp skin just before inoculation by immersion in infectious water. CyHV-3 entry in carp was drastically enhanced on the area of the skin where the mucus was removed with or without associated epidermal lesion. To investigate whether skin mucus inhibits CyHV-3 binding to epidermal cells, tail fins with an intact mucus layer or without mucus were inoculated ex vivo. While electron microscopy examination revealed numerous viral particles bound on the fins inoculated after mucus removal, no particle could be detected after infection of mucus-covered fins. Finally, anti-CyHV-3 neutralising activity of mucus extract was tested in vitro. Incubation of CyHV-3 with mucus extract reduced its infectivity in a dose dependent manner. The present study demonstrates that skin mucus removal and epidermal lesions enhance CyHV-3 entry in carp. It highlights the role of fish skin mucus as an innate immune protection against viral epidermal entry.

Cyprinid herpesvirus 3

TOC summary: This virus is useful for fundamental and applied research.

The recently designated cyprinid herpesvirus 3 (CyHV-3) is an emerging agent that causes fatal disease in common and koi carp. Since its emergence in the late 1990s, this highly contagious pathogen has caused severe financial losses in common and koi carp culture industries worldwide. In addition to its economic role, recent studies suggest that CyHV-3 may have a role in fundamental research. CyHV-3 has the largest genome among viruses in the order Herpesvirales and serves as a model for mutagenesis of large DNA viruses. Other studies suggest that the skin of teleost fish represents an efficient portal of entry for certain viruses. The effect of temperature on viral replication suggests that the body temperature of its poikilotherm host could regulate the outcome of the infection (replicative vs. nonreplicative). Recent advances with regard to CyHV-3 provide a role for this virus in fundamental and applied research.

[Viral homologues of G-protein-coupled receptor]

G-protein-coupled receptors (GPCR) are seven transmembrane proteins that convert extracellular stimuli to cell signaling.Viral genes homologous to cellular GPCR have been described in the genome of Betaherpesvirinae, Gammaherpesvirinae and Poxviridae. The goal of this review is to summarize the knowledge available on viral GPCR (vGPCR) with a special interest for their roles in the biology and the pathogenesis of the infection. This review highlights some properties of vGPCR that are not shared by their cellular homologues and stresses the diversity of their functions in the biology of the infection.

Natural antibody--complement dependent neutralization of bovine herpesvirus 4 by human serum

In contrast to most gammaherpesviruses, Bovine herpesvirus 4 (BoHV-4) has a broad range of host species both in vitro and in vivo. Several in vitro studies demonstrated that some human cell lines are sensitive or even permissive to BoHV-4. These observations led to the hypothesis that cross-species transmission of BoHV-4 could lead to human infections. In the present study, we investigate the sensitivity of BoHV-4 to neutralization by naïve human sera in order to determine if humans exhibit innate anti-viral activities against this virus. Our results demonstrate that human sera from naïve individuals, in contrast to the sera of naïve subjects from various animal species, neutralize BoHV-4 efficiently. A series of complementary experiments were performed to unravel the mechanism(s) of this neutralization. The data obtained in this study demonstrates that human serum neutralizes BoHV-4 in a complement dependent manner activated by natural antibodies raised against the Galalpha1-3Galbeta1-4GlcNAc-R epitope expressed by bovine cells.

Felid herpesvirus 1 glycoprotein G is a structural protein that mediates the binding of chemokines on the viral envelope

Glycoprotein G (gG) orthologues have been described in several alphaherpesviruses. gG is expressed both as a membrane-anchored form on infected cells and as a secreted form. Recently, we reported that both forms of gG encoded by alphaherpesviruses infecting large herbivores and by Felid herpesvirus 1 (FeHV-1) bind with high affinity to a broad range of CXC, CC and C-chemokines. Based on the viral species, gG has been reported either as a structural or a non-structural protein. To date, the incorporation of FeHV-1 gG into virions has never been tested, nor the property of alphaherpesvirus structural gG to bind chemokines on the virion surface. In the present study, to address these questions, various FeHV-1 gG recombinant strains were produced using an original technique based on an infectious FeHV-1 BAC clone and restriction endonuclease mediated recombination. Using the recombinants produced, we were able to determine that FeHV-1 gG is a structural protein that acts as a chemokine-binding protein on the virion surface. In the light of these results, putative roles of gG in alphaherpesvirus infections are discussed, and an evolutionary scenario is proposed to explain the structural versus non-structural property of gG amongst alphaherpesviruses.

Both soluble and membrane-anchored forms of Felid herpesvirus 1 glycoprotein G function as a broad-spectrum chemokine-binding protein

Recently, glycoprotein G (gG) of several alphaherpesviruses infecting large herbivores was shown to belong to a new family of chemokine-binding proteins (vCKBPs). In the present study, the function of Felid herpesvirus 1 (FeHV-1) gG as a vCKBP was investigated and the following conclusions were reached: (i) FeHV-1 secreted gG is a high-affinity broad-spectrum vCKBP that binds CC, CXC and C chemokines; (ii) gG is the only vCKBP expressed by FeHV-1 that binds CCL3 and CXCL1; (iii) secreted gG blocks chemokine activity by preventing their interaction with high-affinity cellular receptors; (iv) the membrane-anchored form of gG expressed on the surface of infected cells is also able to bind chemokines; and (v) the vCKBP activity is conserved among different field isolates of FeHV-1. Altogether, these data demonstrate that FeHV-1 gG is a new member of the vCKBP-4 family. Moreover, this study is the first to demonstrate that gG expressed at the surface of FeHV-1-infected cells can also bind chemokines.

Haemoglobin J-Biskra: a new mildly unstable alpha1 gene variant with a deletion of eight residues (alpha50-57, alpha51-58 or alpha52-59) including the distal histidine

Single point mutation, which accounts for 92% of the 700 known variants, is the most frequent genetic defect responsible for abnormal haemoglobins. Small deletions (or insertions) involving from one to five residues are also observed, but in only approximately 5% of cases. The remaining variants produce fusion or extended haemoglobins. A deletion of eight residues, which included the distal histidine and its neighbours (alpha50-57, alpha51-58 or alpha52-59), was found in Hb J-Biskra. This new alpha-chain variant was mildly unstable in vitro only and there was no haematological or biochemical evidence of haemolysis in the affected family members. 24 nucleotides were missing in a region of the alpha1 gene showing an identical sequence of eight nucleotides at both ends. Several starting points could therefore lead to the same nucleotide and aminoacid remaining sequence. This deletion is the largest up to now reported in a haemoglobin molecule which is expressed at an almost normal level in the red blood cell. Comparison of the DNA sequences near to the deleted (or inserted) regions in the various haemoglobins carrying this type of abnormality almost always revealed the presence of a sequence that was hypothesized to slow down progression of the replication fork, and of repeats that may lead to possible secondary structures favouring slipped mispairing.

Polyvariant mutant cystic fibrosis transmembrane conductance regulator genes. The polymorphic (Tg)m locus explains the partial penetrance of the T5 polymorphism as a disease mutation

In congenital bilateral absence of the vas deferens patients, the T5 allele at the polymorphic Tn locus in the CFTR (cystic fibrosis transmembrane conductance regulator) gene is a frequent disease mutation with incomplete penetrance. This T5 allele will result in a high proportion of CFTR transcripts that lack exon 9, whose translation products will not contribute to apical chloride channel activity. Besides the polymorphic Tn locus, more than 120 polymorphisms have been described in the CFTR gene. We hypothesized that the combination of particular alleles at several polymorphic loci might result in less functional or even insufficient CFTR protein. Analysis of three polymorphic loci with frequent alleles in the general population showed that, in addition to the known effect of the Tn locus, the quantity and quality of CFTR transcripts and/or proteins was affected by two other polymorphic loci: (TG)m and M470V. On a T7 background, the (TG)11 allele gave a 2.8-fold increase in the proportion of CFTR transcripts that lacked exon 9, and (TG)12 gave a sixfold increase, compared with the (TG)10 allele. T5 CFTR genes derived from patients were found to carry a high number of TG repeats, while T5 CFTR genes derived from healthy CF fathers harbored a low number of TG repeats. Moreover, it was found that M470 CFTR proteins matured more slowly, and that they had a 1.7-fold increased intrinsic chloride channel activity compared with V470 CFTR proteins, suggesting that the M470V locus might also play a role in the partial penetrance of T5 as a disease mutation. Such polyvariant mutant genes could explain why apparently normal CFTR genes cause disease. Moreover, they might be responsible for variation in the phenotypic expression of CFTR mutations, and be of relevance in other genetic diseases.

CFTR gene mutations in adults with disseminated bronchiectasis

The severity and type of clinical manifestations are variable in patients with cystic fibrosis (CF). The respiratory syndromes in these patients consist of lung infections associated with disseminated bronchiectasis (DB), asthma, and chronic obstructive pulmonary disease. To investigate the possible involvement of the cystic fibrosis transmembrane conductance regulator (CFTR) gene in chronic pulmonary disease in adults, we studied 32 DB patients with a clinically isolated respiratory syndrome. Careful analysis of all the CFTR gene exons and their flanking regions revealed a significantly increased frequency of CFTR gene mutations in these patients. Thirteen CFTR gene mutations were identified in sixteen different alleles. Six of these mutations, which have previously been reported as CF defects, were found on nine alleles. A further four, two of which had not previously been described (D192N and 406-2 AdeltaC), are potentially disease-causing mutations. We also identified three rare substitutions (R31C, L997F, T1220I), which could be involved in mild CFTR gene disease. Four patients were compound heterozygotes, one carried two CFTR gene mutations (possibly allelic) and six were heterozygous for a mutation. These results indicate that CFTR gene mutations may play a role in bronchiectatic lung disease, possibly in a multifactorial context. These findings have implications for genetic counselling of DB patients and their families.

Haplotype analysis of 94 cystic fibrosis mutations with seven polymorphic CFTR DNA markers

We have analyzed 416 normal and 467 chromosomes carrying 94 different cystic fibrosis (CF) mutations with polymorphic genetic markers J44, IVS6aGATT, IVS8CA, T854, IVS17BTA, IVS17BCA, and TUB20. The number of mutations found with each haplotype is proportional to its frequency among normal chromosomes, suggesting that there is no preferential haplotype in which mutations arise and thus excluding possible selection for specific haplotypes. While many common mutations in the worldwide CF population showed absence of haplotype variation, indicating their recent origins, some mutations were associated with more than one haplotype. The most common CF mutations, delta F508, G542X, and N1303K, showed the highest number of slippage events at microsatellites, suggesting that they are the most ancient CF mutations. Recurrence was probably the case for 9 CF mutations (R117H, H199Y, R347YH, R347P, L558S, 2184insA, 3272-26A-->G, R1162X, and 3849 + 10kbC-->T). This analysis of 94 CF mutations should facilitate mutation screening and provides useful data for studies on population genetics of CF.

[Cystic fibrosis: the CFTR gene, its mutations, the genetic counseling]

Cystic fibrosis is the most frequent autosomic recessively inherited disease in the European population. The gene implicated in this disease was cloned in 1989 but the consequences of the biochemical defect in the cell have not been fully elucidated. To date, 500 mutations of this 230 kilobase gene have been identified. These molecular anomalies each have an effect on the encoded protein (CFTR) an ion channel which appears to play a role in regulator functions. Results of the gene cloning and research into the different mutations have led to the development of effective strategies for molecular diagnosis facilitating genetic counselling for families at risk and the identification of atypical forms of the disease.

Frequent occurrence of the CFTR intron 8 (TG)n 5T allele in men with congenital bilateral absence of the vas deferens

Isolated congenital bilateral absence of the vas deferens (CBAVD) is an autosomal recessive disorder which has recently been shown to be associated with cystic fibrosis (CF) mutations. As part of an effort to understanding the genetic basis of this disorder, we have analysed the entire coding sequence and all the intron/exon boundaries of the cystic fibrosis transmembrane conductance regulator (CFTR) gene from 45 azoospermic individuals with this phenotype. We were able to detect a CFTR gene defect in 86% of chromosomes from these subjects. In addition to identifying 9 novel CFTR gene mutations, we found that a surprisingly high proportion (84%) of men with CBAVD who are heterozygous for a CF mutation carry the intron 8 polypyrimidine 5T CFTR allele on one chromosome. We hypothesise that this tight and significant (p < 10(-6)) linkage reflects the very mild impact of this mutation on CFTR gene expression. Although genetic heterogeneity cannot be excluded, CBAVD patients in whom no CFTR mutation has been detected are likely to harbour additional unidentified mild mutations. These observations have implications for the genetic counselling of CBAVD patients and CF families, and couples undergoing in vitro fertilisation procedures.

Identification of eight mutations and three sequence variations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene

To determine cystic fibrosis (CF) defects in a sample of 224 non-delta F508 CF chromosomes, we used denaturing gradient gel multiplex analysis of CF transmembrane conductance regulator gene segments, a strategy based on blind exhaustive analysis rather than a search for known mutations. This process allowed us to detect 11 novel variations comprising two nonsense mutations (Q890X and W1204X), a splice defect (405 + 4 A-->G), a frameshift (3293delA), four presumed missense mutations (S912L, H949Y, L1065P, Q1071P), and three sequence polymorphisms (R31C or 223 C/T, 3471 T/C, and T1220I or 3791 C/T). We describe these variations, together with the associated phenotype when defects on both CF chromosomes were identified.

Screening for cystic fibrosis in dried blood spots of newborns

We propose a newborn cystic fibrosis (CF) screening test based on the analysis of dried blood spot DNA by a strategy involving simple or multiplex denaturing gradient gel electrophoresis (DGGE) of PCR products of CFTR gene fragments, in conjunction with the immunoreactive-trypsin (IRT) assay. From May 1988 to May 1992 we have performed a neonatal screening programme of 42,000 newborns in Brittany. We identified 450 infants with an elevated IRT level. From this cohort, to evaluate the feasibility of measuring IRT in conjunction with mutation analysis in Guthrie cards, a pilot study was initially conducted on 200 individuals with normal IRT and 150 with raised IRT levels. Furthermore, a retrospective study was performed on 189 IRT positive cards, involving mutation scanning of exons 10 and 11 of the CFTR gene, which contains a number of frequent mutations including the deletion delta F508. We show that this approach has several implications for neonatal CF screening especially in decreasing the recall rate and detecting CF carriers.

Psoralen-modified oligonucleotide primers improve detection of mutations by denaturing gradient gel electrophoresis and provide an alternative to GC-clamping

Denaturing gradient gel electrophoresis (DGGE), a mutation-scanning procedure separating DNA fragments differing by as little as a single base change, is widely used in studies of genomic nucleotide sequence variability. The efficiency of the technique is greatly enhanced by attaching, through polymerase chain reaction (PCR) incorporation, a long GC-tail to the test DNA sequence which, as a result, becomes analysable throughout. As synthesis of GC-rich specific PCR primers is costly and time-consuming, we attempted to clamp the DNA fragment using a psoralen derivative (ChemiClamp) that promotes photo-induced cross-linking at one end. We found that this procedure provides an attractive alternative to GC-clamp in DGGE (and temperature gradient gel electrophoresis) and should prove useful in both research and diagnostic laboratories.

[The cystic fibrosis gene, its product CFTR protein and its mutations]

Cystic fibrosis (CF) is a fatal genetic disease primarily affecting Caucasians. Its etiology is complex, but it is chiefly a disease of electrolyte transport characterized by defects in fluid secretion by several epithelia. In this review are analyzed the data obtained since the cloning of the CF gene and the characterization of its product, the CF transmembrane conductance regulator (CFTR) protein, which has been shown to act like a cAMP-regulated chloride channel. This protein is a member of a family of ATP-binding proteins that are membrane-spanning, are found in a number of prokaryotic and eucaryotic cells, and have two ATP-binding domains. Unique to this family of proteins, the CFTR possesses an additional highly charged domain (the R domain). The majority of CF chromosomes (70%) have a single Phenylalanine codon deletion at position 508 of the protein (delta F508). A large number of other rare mutations (more than 230) have also been identified. This rapid accumulation of data is essential to genetic diagnosis and will aid in understanding the structure and function of the protein.

Twenty-four novel hemophilia B mutations revealed by rapid scanning of the whole factor IX gene in a French population sample

Full scanning of the factor IX gene by means of denaturing gradient gel electrophoresis enabled us to determine the molecular defects in 48 out of 49 hemophiliacs and to evaluate the spectrum of factor IX mutations in the French population. Our results further document the high molecular heterogeneity of the disease and the efficiency of this rapid screening method for disease-causing mutations. This direct approach, which is based on computer-aided analysis of the whole coding, promoter and exon-flanking factor IX gene sequences, proved to be helpful for carrier detection and prenatal diagnosis in most hemophilia B families, including sporadic cases. Moreover, we were able to identify 24 novel molecular defects of various natures in the factor IX gene.

A rapid, efficient, and sensitive assay for simultaneous detection of multiple cystic fibrosis mutations

We describe the use of DGGE multiplex systems for rapid analysis of 15 exons of the cystic fibrosis transmembrane conductance regulator (CFTR) gene, in which about half of the known CF molecular defects are clustered. We have previously determined the spectrum of mutations affecting the CFTR gene in the French population using a strategy based on denaturing gradient gel electrophoresis (DGGE) of amplified gene segments. Analysis of CF patients' DNA with five DGGE multiplex systems permitted us to characterize nearly 35% of non-delta F508 CF alleles and increased the CF allele detection rate to almost 82% in this population. This simple and rapid multiplex analysis strategy, which allows a significant proportion of the most frequent CF mutations in Caucasians to be detected, will be helpful in the implementation of genetic screening programs.

Molecular characterization of cystic fibrosis: 16 novel mutations identified by analysis of the whole cystic fibrosis conductance transmembrane regulator (CFTR) coding regions and splice site junctions

The spectrum of cystic fibrosis (CF) mutations was determined in 105 patients by using denaturing gradient gel electrophoresis to screen the entire coding regions and adjacent cystic fibrosis transmembrane conductance regulator (CFTR) gene sequences. The nucleotide substitutions detected included 16 novel mutations, 11 previously described defects, and 11 nucleotide sequence polymorphisms. Among the novel mutations, 6 were of the missense type, 4 were nonsense mutations, 4 were frameshift defects, and 2 affected mRNA splicing. The mutations involved all the CFTR domains, including the R domain. Of the 61 non-delta F508 CF chromosomes studied, mutations were found on 36 (59%), raising the proportion of CF alleles characterized in our patient cohort to 88%. Given the efficacy of the screening method used, the remaining uncharacterized mutations probably lie in DNA sequences outside the regions studied, e.g., upstream-promoter sequences, the large introns, or putative regulatory regions. Our results further document the highly heterogeneous nature of CF mutations and provide the information required for DNA-based genetic testing.