Peptide Amphiphiles for Pharmaceutical Applications.

During the last few decades, several efforts have been made towards developing biocompatible materials. Among them, peptide amphiphiles (PAs) constitute a novel nanotechnological strategy used in the field of biomedicine since they can provide tissue- specific binding and localization. PAs possess several regions combining hydrophobic and hydrophilic areas that are able to self-assemble in aqueous media, forming different tertiary nanostructures able to interact with cellular membranes. Moreover, these molecules can be tuned by incorporating collagen, lipids, or fluorescent markers. In addition, they can also be used as carriers in order to encapsulate active compounds for drug delivery showing promising features in this area. In this review, the self-assembled structures of PAs as well as their pharmacological applications have been summarized. Furthermore, their use as drug delivery systems has been highlighted and the latest advances in this field have been reviewed.

Atorvastatin-loaded peptide amphiphiles against corneal neovascularization.

Background: Corneal neovascularization is a sight-threatening disease. It can be treated using antiangiogenic and anti-inflammatory compounds. Therefore, atorvastatin (ATV) constitutes a suitable candidate to be administered topically. To attain suitable efficacy, ATV can be encapsulated into custom-developed nanocarriers such as peptide amphiphiles. Methods: Three peptide amphiphiles bearing one, two or four C16-alkyl groups (mC16-Tat47-57, dC16-Tat47-57 and qC16-Tat47-57) were synthesized, characterized and loaded with ATV. Drug release and ocular tolerance were assessed as well as anti-inflammatory and antiangiogenic properties. Results: ATV-qC16-Tat47-57 showed higher encapsulation efficiency than mC16-Tat47-57 and dC16-Tat47-57 and more defined nanostructures. ATV-qC16-Tat47-57 showed ATV prolonged release with suitable ocular tolerance. Moreover, ATV-qC16-Tat47-57 was antiangiogenic and prevented ocular inflammation. Conclusion: ATV-qC16-Tat47-57 constitutes a promising topical medication against corneal neovascularization.

Corneal neovascularization is an eye disease that affects over 1 million people every year and can lead to blindness. It is caused by inflammation and the unwanted formation of blood vessels in the eye. Current treatments for this disease are not fully effective. Atorvastatin (ATV) is one drug that has been partially successful at treating corneal neovascularization, but it does not stay in the eye long enough and does not mix well with the water-based environment of the eye. To overcome this, ATV was combined with three specially designed nanocarriers. These nanocarriers were peptides, short stretches of protein. They were designed to be amphiphilic, meaning that one section is hydrophilic (literally meaning 'water loving') and one section is hydrophobic ('water hating'). These peptide nanocarriers allowed ATV to stay in the water-based environment of the eye longer. The peptide with the most hydrophobic chains (qC₁₆-Tat_47-57) was able to carry more ATV than the other peptides and produced particles of a desired shape. ATV-qC₁₆-Tat_47-57 nanocarriers were found to release slowly. These nanocarriers were also found to prevent the development of new blood vessels on a membrane in a hen's egg used to mimic the eye. There was also no sign of irritation on this membrane or in the eyes of New Zealand rabbits. These results show ATV-qC₁₆-Tat_47-57 has a prolonged therapeutic effect, prevents the formation of new blood vessels and is tolerated in the eye. ATV-qC₁₆-Tat_47-57 is therefore potentially a more effective alternative to ATV treatment alone.

Big dynorphin is a neuroprotector scaffold against amyloid ß-peptide aggregation and cell toxicity.

Amyloid ß-peptide (Aß) misfolding into ß-sheet structures triggers neurotoxicity inducing Alzheimer's disease (AD). Molecules able to reduce or to impair Aß aggregation are highly relevant as possible AD treatments since they should protect against Aß neurotoxicity. We have studied the effects of the interaction of dynorphins, a family of opioid neuropeptides, with Aß40 the most abundant species of Aß. Biophysical measurements indicate that Aß40 interacts with Big Dynorphin (BigDyn), lowering the amount of hydrophobic aggregates, and slowing down the aggregation kinetics. As expected, we found that BigDyn protects against Aß40 aggregates when studied in human neuroblastoma cells by cell survival assays. The cross-interaction between BigDyn and Aß40 provides insight into the mechanism of amyloid pathophysiology and may open up new therapy possibilities.

Development of Peptide Targeted PLGA-PEGylated Nanoparticles Loading Licochalcone-A for Ocular Inflammation.

Licochalcone-A is a natural compound with anti-inflammatory properties. However, it possesses low water solubility, making its application for the treatment of ocular inflammation difficult. To overcome this drawback, biodegradable nanoparticles incorporating Licochalcone-A have been developed. Additionally, to avoid fast clearance and increase cellular internalization into the ocular tissues, PLGA nanoparticles have been functionalized using PEG and cell penetrating peptides (Tet-1 and B6). To optimize the formulations, a factorial design was carried out and short-term stability of the nanoparticles was studied. Moreover, morphology was also observed by transmission electron microcopy and in vitro drug release was carried out. Ocular tolerance of the formulations was ensured in vitro and in vivo and anti-inflammatory therapeutic efficacy was also assessed. Surface functionalized nanoparticles loading Licochalcone-A were developed with an average size below 200 nm, a positive surface charge, and a monodisperse population. The formulations were non-irritant and showed a prolonged Licochalcone-A release. Despite the fact that both Licochalcone-A Tet-1 and B6 functionalized nanoparticles demonstrated to be suitable for the treatment of ocular inflammation, B6 targeted nanoparticles provided greater therapeutic efficacy in in vivo assays.

Nanotechnology-Based Platforms for Vaginal Delivery of Peptide Microbicides.

BACKGROUND: Vaginal drug delivery offers an opportunity for effective microbicide treatments. However, the physiological characteristics of the vagina represent a challenge when preparing microbicide formulations for local delivery that avoid systemic effects. OBJECTIVE: To review recent advances in vaginal microbicides placing special emphasis on nanocarriers that encapsulate peptide microbicides. The review includes an overview of local treatment and prevention strategies for bactericidal, fungal, protozoal and viral vaginal infections that use peptide microbicides. METHODS: Scientific literature and clinical trials published in the PubMed database since 2015 are analyzed. RESULT: Peptide microbicides are used for vaginal drug delivery as a means of prevention and treatment of several infectious diseases, especially sexually transmitted infections, and it is clear that such peptide-based microbicides constitute a suitable strategy. Their combination with nanotechnological drug delivery systems improves local peptide administration while avoiding their degradation and adverse effects. To date, only a few polymeric and lipid-based nanocarriers have been used for peptide microbicide vaginal delivery. CONCLUSION: The combination of nanotechnology and peptide microbicides has emerged over recent years, and different platforms are being used for vaginal peptide delivery. Nanostructured systems for peptide delivery via vaginal rings or hydrogels are increasingly used as platforms capable of providing suitable drug delivery. However, there is still a lack of knowledge about nanocarriers aimed at encapsulating peptides for local microbicide delivery.

Anti-carbamylated protein antibody isotype pattern differs between palindromic rheumatism and rheumatoid arthritis.

BACKGROUND: A restricted response against citrullinated peptides/proteins, with less isotype usage, has been found in palindromic rheumatism (PR) in comparison with rheumatoid arthritis (RA). We hypothesized that this different antibody response may be observed for other post-translational modified proteins. We compared the prevalence and isotype usage of two specificities of anti-carbamylated peptide/protein antibodies (Anti-CarP) in patients with PR and RA. METHODS: Cross-sectional study including 54 patients with pure PR and 53 patients with RA, matched by sex, age, disease duration and ACPA. Anti-CarP specificities were determined by home-made enzyme-linked immunosorbent assay tests using a synthetic chimeric fibrin/filaggrin homocitrullinated peptide (CFFHP) and fetal calf serum (FCS) homocitrullinated protein as antigens. IgG, IgA and IgM isotypes were measured. RESULTS: Anti-CarP were positive (CFFHP or FCS) in 24% and 64% of patients with PR and RA, respectively (p < 0.005). All Anti-CarP isotype proportions were significantly lower in PR than in RA: Anti-CarP-IgG (24% versus 51%), Anti-CarP-IgA (7% versus 34%) and Anti-CarP-IgM (7% versus 36%). Mean titers of Anti-CarP isotypes were also lower in PR. In Anti-CarP positive patients, the isotype distribution differed between PR and RA: IgG Anti-CarP was used in all PR patients and in 79% of RA patients. By contrast, a significantly lower isotype usage of both IgA (31% versus 53%) and IgM (31% versus 56%) was observed in PR patients. No significant differences in clinical or demographic characteristics were observed according to Anti-CarP status in PR patients, except for a higher prevalence of ACPA and higher mean titers of ACPA and rheumatoid factor in Anti-CarP positive patients. CONCLUSION: Anti-CarP are found in patients with PR but in a lower proportion and with a different isotype usage from in RA, suggesting a distinct B cell response to homocitrullinated antigens in PR.

Efficacy and tolerability of perampanel as a first add-on therapy with different anti-seizure drugs.

PURPOSE: To investigate the efficacy and tolerability of perampanel (PER) when administered as a first add-on therapy to patients with focal epilepsy or idiopathic generalized epilepsy (IGE) taking one other antiseizure drug (ASD). METHODS: This multicentre, retrospective, one-year observational study collected data from patients (≥12 years) who initiated treatment with PER as first add-on therapy. Patients had to be experiencing inadequate seizure control on ASD monotherapy and tried ≤3 ASD monotherapies before initiating PER. Multivariate logistic regression analyses were performed, adjusted for the number and type of previous seizures, duration and aetiology of epilepsy. RESULTS: Of the 149 patients included in the study (mean age 41 years; 54.4 % male), 118 (79.2 %) were still receiving PER as first add-on treatment after 12 months. Mean PER dose was 6.2 mg/day. At 12 months, 45.6 % were seizure-free and 84.6 % responders. A significant difference in seizure freedom rate was found between patients with IGE and patients with focal epilepsy, but not in responders. Reduced seizure control was observed when PER was administered with strong enzyme-inducing ASDs; conversely, increased seizure control was seen when the same dose of PER was combined with enzyme-inhibiting ASDs. The most frequent adverse events were dizziness (15.4 %), irritability (14.1 %) and drowsiness (14.1 %); no differences in tolerance were observed among different combinations. CONCLUSION: PER demonstrated a good efficacy and safety profile when used as a first add-on therapy in patients who did not respond to monotherapy. PER dose adjustments may optimize seizure control when combined with strong enzyme-inducing or enzyme-inhibiting ASDs.

Lipid Vesicles Loaded with an HIV-1 Fusion Inhibitor Peptide as a Potential Microbicide.

The effective use of fusion inhibitor peptides against cervical and colorectal infections requires the development of sustained release formulations. In this work we comparatively study two different formulations based on polymeric nanoparticles and lipid vesicles to propose a suitable delivery nanosystem for releasing an HIV-1 fusion inhibitor peptide in vaginal mucosa. Polymeric nanoparticles of poly-d,l-lactic-co-glycolic acid (PLGA) and lipid large unilamellar vesicles loaded with the inhibitor peptide were prepared. Both formulations showed average sizes and polydispersity index values corresponding to monodisperse systems appropriate for vaginal permeation. High entrapment efficiency of the inhibitor peptide was achieved in lipid vesicles, which was probably due to the peptide's hydrophobic nature. In addition, both nanocarriers remained stable after two weeks stored at 4 °C. While PLGA nanoparticles (NPs) did not show any delay in peptide release, lipid vesicles demonstrated favorably prolonged release of the peptide. Lipid vesicles were shown to improve the retention of the peptide on ex vivo vaginal tissue in a concentration sufficient to exert its pharmacological effect. Thus, the small size of lipid vesicles, their lipid-based composition as well as their ability to enhance peptide penetration on vaginal tissue led us to consider this formulation as a better nanosystem than polymeric nanoparticles for the sustained delivery of the HIV-1 fusion inhibitor peptide in vaginal tissues.

Anti-carbamylated proteins antibody repertoire in rheumatoid arthritis: evidence of a new autoantibody linked to interstitial lung disease.

OBJECTIVE: To analyse the association between anti-carbamylated protein antibodies (Anti-CarP) and interstitial lung disease (ILD) in rheumatoid arthritis (RA) patients. METHODS: Cross-sectional study including RA patients fulfilling the 2010 ACR/EULAR criteria. The main population comprised two groups: (1) RA patients diagnosed with RA-ILD (RA-ILD group); (2) RA patients without ILD (non-ILD RA group). Non-ILD RA patients in whom ILD was suspected underwent a diagnostic work-up and, if ILD was diagnosed, were switched to the RA-ILD group. ILD was diagnosed by high-resolution computed tomography and confirmed by a multidisciplinary committee. An independent replication sample was also obtained. Three Anti-CarP IgG autoantibodies against fetal calf serum (Anti-FCS), fibrinogen (Anti-Fib) and chimeric fibrine/filagrine homocitrullinated peptide (Anti-CFFHP) and one Anti-CarP IgA against FCS (Anti-FCS-IgA) were determined by home-made ELISA. Associations between Anti-CarP and ILD were analysed using multivariable logistic regression adjusted by smoking, sex, age, RA disease duration, rheumatoid factor and anticitrullinated protein antibodies. RESULTS: We enrolled 179 patients: 37 (21%) were finally diagnosed with RA-ILD. Anti-CarP specificities were more frequent in RA-ILD patients (Anti-FCS 70% vs 43%; Anti-Fib 73% vs 51%; Anti-CFFHP 38% vs 19%; Anti-CarP-IgA 51% vs 20%, p<0.05 for all comparisons). Serum titers of Anti-CarP were significantly higher in RA-ILD patients. Anti-CarP specificities showed a robust effect towards increasing the odds of ILD in the multivariate analysis (Anti-FCS (OR: 3.42; 95% CI: 1.13 to 10.40), Anti-Fib (OR: 2.85; 95% CI: 0.83 to 9.70), Anti-CFFHP (OR: 3.11; 95% CI: 1.06 to 9.14) and Anti-FCS-IgA (OR: 4.30; 95% CI: 1.41 to 13.04)). Similar findings were observed in the replication sample. CONCLUSIONS: Anti-CarP were strongly associated with ILD. The role of homocitrullination in RA-ILD merits further investigation.

Development of a multiplex assay based on chimeric citrullinated peptides as proof of concept for diagnosis of rheumatoid arthritis.

Anti-citrullinated peptide/protein antibodies (ACPAs) are the most specific serological biomarkers for rheumatoid arthritis (RA). They have both diagnostic and prognostic value, and are related to more aggressive joint disease in RA. However, a single biomarker cannot differentiate RA subtypes. So, simultaneous analysis of target citrullinated peptides, using a multiplex array based on chimeric peptides composed of several domains of human proteins, could be useful. In this work, eight chimeric peptides and the corresponding native arginine-containing control peptides were obtained by solid-phase peptide synthesis. The study included RA and psoriatic arthritis (PsA) patients attending the Rheumatology Unit of the Hospital Clinic in Barcelona, as well as healthy blood donors (BD) at the same hospital. Our main aim was to explore the diagnostic value of the novel multiplex array compared to a commercial ELISA-based ACPA assay in a serum-saving way. Using the combination of the eight chimeric peptide antigens in the multiplex array, 61.4% of the RA cohort were positive for 3 or more peptides; while, the healthy BD and PsA cohorts did not show any reactivity with the tested peptides. These results indicate that we have developed a highly specific multiplex assay based of chimeric citrullinated peptides derived from filaggrin, fibrin, vimentin and human enolase proteins for the detection of ACPAs in a serum-saving way.

Penetration of polymeric nanoparticles loaded with an HIV-1 inhibitor peptide derived from GB virus C in a vaginal mucosa model.

Despite the great effort to decrease the HIV infectivity rate, current antiretroviral therapy has several weaknesses; poor bioavailability, development of drug resistance and poor ability to access tissues. However, molecules such as peptides have emerged asa new expectative to HIV eradication. The vaginal mucosa is the main spreading point of HIV. There are natural barriers such as the vaginal fluid which protects the vaginal epithelium from any foreign agents reaching it. This work has developed and characterized Nanoparticles (NPs) coated with glycol chitosan (GC), loaded with an HIV-1 inhibitor peptide (E2). In vitro release and ex vivo studies were carried out using the vaginal mucosa of swine and the peptide was determined by HPLC MS/MS validated method. Moreover, the peptide was labeled with 5(6)-carboxyfluoresceine and entrapped into the NPs to carried out in vivo studies and to evaluate the NPs penetration and toxicity in the vaginal mucosa of the swine. The mean size of the NPs, ξ and the loading percentage were fundamental features for to reach the vaginal tissue and to release the peptide within intercellular space. The obtained results suggesting that the fusion inhibitor peptides loaded into the NPs coated with GC might be a new way to fight the HIV-1, due to the formulation might reach the human epithelial mucosa and release peptide without any side effects.

Structural Study of a New HIV-1 Entry Inhibitor and Interaction with the HIV-1 Fusion Peptide in Dodecylphosphocholine Micelles.

Previous studies support the hypothesis that the envelope GB virus C (GBV-C) E1 protein interferes the HIV-1 entry and that a peptide, derived from the region 139-156 of this protein, has been defined as a novel HIV-1 entry inhibitor. In this work, we firstly focus on the characterization of the structural features of this peptide, which are determinant for its anti-HIV-1 activity and secondly, on the study of its interaction with the proposed viral target (i.e., the HIV-1 fusion peptide). We report the structure of the peptide determined by NMR spectroscopy in dodecylphosphocholine (DPC) micelles solved by using restrained molecular dynamics calculations. The acquisition of different NMR experiments in DPC micelles (i.e., peptide-peptide titration, diffusion NMR spectroscopy, and addition of paramagnetic relaxation agents) allows a proposal of an inhibition mechanism. We conclude that a 18-mer peptide from the non-pathogenic E1 GBV-C protein, with a helix-turn-helix structure inhibits HIV-1 by binding to the HIV-1 fusion peptide at the membrane level, thereby interfering with those domains in the HIV-1, which are critical for stabilizing the six-helix bundle formation in a membranous environment.

Differing specificities and isotypes of anti-citrullinated peptide/protein antibodies in palindromic rheumatism and rheumatoid arthritis.

BACKGROUND: To analyze differences in the recognition of anti-citrullinated peptide/protein antibody (ACPA) citrullinated epitopes and isotypes in patients with palindromic rheumatism (PR) and rheumatoid arthritis (RA). METHODS: ACPA fine specificities (citrullinated peptides of enolase, fibrin, and vimentin) and isotypes (IgG, IgM, and IgA) were analyzed in 54 patients with longstanding PR and 54 patients with established RA. RESULTS: CCP2 tested positive in 66.7% of patients with PR and RA. The ACPA distribution of fine specificities and isotypes differed between PR and RA patients. PR patients had a lower frequency of fine ACPA specificities than RA patients, which was significant in the case of a peptide derived from vimentin (PR 24.1% vs. 59.3% RA; p < 0.001). The mean number of ACPA specificities was lower in PR than in RA patients, and only 25.9% of PR patients recognized ≥2 additional specificities compared with 46.3% of RA patients. Significantly less isotype usage, especially IgA, was observed in PR patients. CONCLUSION: The ACPA immune response differed in patients with PR and RA, with fewer fine specificities and isotype usage in patients with PR. Some patients with PR may have impaired maturation of the B-cell response against citrullinated peptides with no progression to RA.

Lipid raft-like liposomes used for targeted delivery of a chimeric entry-inhibitor peptide with anti-HIV-1 activity.

The work reports the design and synthesis of a chimeric peptide that is composed of the peptide sequences of two entry inhibitors which target different sites of HIV-1 gp41. The chimeric peptide offers the advantage of targeting two gp41 regions simultaneously: the fusion peptide and the loop both of which are membrane active and participate in the membrane fusion process. We therefore use lipid raft-like liposomes as a tool to specifically direct the chimeric inhibitor peptide to the membrane domains where the HIV-1 envelope protein is located. Moreover, the liposomes that mimic the viral membrane composition protect the chimeric peptide against proteolytic digestion thereby increasing the stability of the peptide. The described liposome preparations are suitable nanosystems for managing hydrophobic entry-inhibitor peptides as putative therapeutics.

One-year clinical experience of perampanel in Spain: a multicentre study of efficacy and tolerability.

Perampanel, a non-competitive antagonist of the α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptors, is the most recent antiepileptic drug available in Spain, marketed in January 2014. It was initially approved by the European Medicines Agency as adjunctive treatment for partial-onset seizures in patients 12 years and older, but recently also for primary generalized tonic-clonic seizures. Although clinical trials provide essential information about the drug, they do not reflect daily clinical practice. This retrospective study shows the initial experience with perampanel in 11 Spanish hospitals during its first year post-commercialisation. All patients who started perampanel treatment were included, but efficacy and tolerability were only assessed in those patients with a minimum follow-up period of six months. In total, 256 patients were treated with perampanel before September 2014, and 253 had an observational period of one year. After six months, 216/256 patients (84%) continued on perampanel and 180/253 (71.1%) completed one year of treatment. The mean number of previous antiepileptic drugs used was 6.83 and the median number of concomitant antiepileptic drugs was 2. The mean perampanel dose was 7.06 mg and 8.26 mg at six and 12 months, respectively. The responder rate was 39.5% and 35.9% at both follow-up points, respectively. Adverse events were experienced by 91/253 (35.5%) and resulted in withdrawal in 37 (14.6%). The most common adverse events were somnolence, dizziness, and irritability. We found no significant differences between concomitant use of enzyme-inducing and non-inducing antiepileptic drugs, regarding efficacy, adverse effects, or withdrawals. Irritability was not influenced by concomitant use of levetiracetam, relative to other drugs, but was more frequently observed in patients with a history of psychiatric problems or learning disabilities.

Updating the use of synthetic peptides as inhibitors of HIV-1 entry.

The use of synthetic peptides as HIV-1 inhibitors has been the object of research over recent years. A large number of peptides that affect different stages of the HIV-1 life cycle have been and continue to be studied due to their possible clinical application in the fight against HIV-1 infection. The main advantages of synthetic peptides as therapeutic agents are their low systemic toxicity, the fact that structural modifications can be made to them and their resulting capacity to mimic certain substrates or epitopes. HIV-1-inhibiting peptides have been identified and/or developed using different methods. Some therapeutic peptides such as enfuvirtide-already approved for clinical use-are derived from HIV-1 itself. Others are natural peptides such as chemokines, defensins or the "virus inhibitory peptide"; while still others have been designed and synthesized based on crystallographic data on HIV-1 proteins or from peptide libraries. Initial attempts at therapeutic applications focused on HIV-coded enzymes (reverse transcriptase, protease and, more recently, integrase). However, structural HIV proteins and, more specifically, the mechanisms that involve the virus in cell infection and replication are now also considered therapeutic targets. Several chemical strategies to improve both the stability of peptides and their pharmacokinetics, including prolonging their half-life, have recently been described in the literature. There is growing an interest in inhibitors that prevent HIV entry into the host cell (fusion inhibitors) which could lead to the development of new antiviral agents. Knowledge of the mechanism of action of fusion inhibitors is essential not only for the development of future generations of entry inhibitors, but also to gain an understanding of the form and kinetics of membrane fusion induced by the virus. The physico-chemical processes involved at the interface between the lipid surface of cells and enveloped viruses (such as HIV-1) are essential to the action of peptides that prevent HIV-1 entry into the host cell. The interaction of these peptides with biological membranes may be related to their inhibition efficiency and to their mechanism of action, as the HIV-1 gp41 glycoprotein is bound and confined between the cellular membrane and the viral envelope.

Oligonucleotide-peptide conjugates: solid-phase synthesis under acidic conditions and use in ELISA assays.

Here we used solid-phase methods to prepare oligonucleotides carrying fibrin/ filaggrin citrullinated peptides. Post-synthetic conjugation protocols were successfully applied for the synthesis of oligonucleotides carrying small peptides. A stepwise protocol using acid treatment for the final deprotection allowed the preparation of polypyrimidine oligonucleotides carrying longer and arginine-rich peptides. An ELISA-based test using the oligonucleotide-citrullinated peptide conjugates was developed for the detection of anti-citrullinated protein/peptide antibodies in human serum from rheumatoid arthritis patients.

Anti-citrullinated peptide antibodies in the serum of heavy smokers without rheumatoid arthritis. A differential effect of chronic obstructive pulmonary disease?

The objective of this study is to analyse the frequency and levels of anti-citrullinated peptide/protein antibodies (ACPA) in the serum of non-rheumatoid arthritis (RA) heavy smokers with and without chronic obstructive pulmonary disease (COPD) and compare them with healthy never smokers and patients with RA. Serum samples of 110 heavy smokers without RA, 209 healthy never smokers and 134 patients with RA were tested for ACPA using a commercial anti-cyclic citrullinated peptide antibodies (CCP2) test and a homemade chimeric fibrin/filaggrin citrullinated synthetic peptide (anti-CFFCP) ELISA test. The frequency of positive results and autoantibody levels were compared between groups. The prevalence of the two types of ACPA was slightly higher in heavy smokers than in never smokers, although the difference was not significant, and significantly lower than in RA patients. The highest prevalence of positive ACPA in heavy smokers was found in subjects with COPD (7.4% of positive anti-CFFCP in patients with COPD in comparison with 2.4% in never smokers: OR 3.26; 95% CI 0.85-12.6, p = 0.089). Mean serum levels of ACPA in heavy smokers were not significantly different from those of never smokers. Heavy smokers with COPD had significantly higher levels of anti-CFFCP than those without COPD, although almost all patients had serum levels below the cut-off values. The prevalence of ACPA in heavy smokers without RA is low, but seems to be higher in heavy smokers with COPD. Larger studies are necessary to confirm these findings and determine the relationship between ACPA and lung disease.

Carbon nanotube composite peptide-based biosensors as putative diagnostic tools for rheumatoid arthritis.

This work reports on the fabrication and performance of a simple amperometric immunosensor device to be potentially used for the detection of serum anti-citrullinated peptide antibodies (ACPAs), which are specific for rheumatoid arthritis (RA) autoimmune disease. Sera of RA patients contain antibodies to different citrullinated peptides and proteins such as fibrin or filaggrin. Herein, a chimeric fibrin-filaggrin synthetic peptide (CFFCP1) was used as a recognition element anchored to the surface of a multiwalled carbon nanotube-polystyrene (MWCNT-PS) based electrochemical transducer. The transducer fabrication process is described in detail together with its successful electrochemical performance in terms of repeatability and reproducibility of the corresponding amperometric response. The resulting immunosensor approach was initially tested in sera of rabbits previously inoculated with the synthetic peptide and eventually applied to the detection of ACPAs in human sera. A comparative study was carried out using control serum from a blood donor, which demonstrated the selectivity of the immunosensor response and its sensitivity for the detection of anti-CFFCP1 antibodies present in RA patients.