Identification of 7-Ketocholesterol-Modulated Pathways and Sterculic Acid Protective Effect in Retinal Pigmented Epithelium Cells by Using Genome-Wide Transcriptomic Analysis.

Age-related macular degeneration (AMD) is the leading cause of blindness in developed countries. AMD is characterized by the formation of lipidic deposits between the retinal pigment epithelium (RPE) and the choroid called drusen. 7-Ketocholesterol (7KCh), an oxidized-cholesterol derivative, is closely related to AMD as it is one of the main molecules accumulated in drusen. 7KCh induces inflammatory and cytotoxic responses in different cell types, and a better knowledge of the signaling pathways involved in its response would provide a new perspective on the molecular mechanisms that lead to the development of AMD. Furthermore, currently used therapies for AMD are not efficient enough. Sterculic acid (SA) attenuates the 7KCh response in RPE cells and is presented as an alternative to improve these therapies. By using genome-wide transcriptomic analysis in monkey RPE cells, we have provided new insight into 7KCh-induced signaling in RPE cells, as well as the protective capacity of SA. 7KCh modulates the expression of several genes associated with lipid metabolism, endoplasmic reticulum stress, inflammation and cell death and induces a complex response in RPE cells. The addition of SA successfully attenuates the deleterious effect of 7KCh and highlights its potential for the treatment of AMD.

Toxic Determination of Cry11 Mutated Proteins Obtained Using Rational Design and Its Computational Analysis.

Cry11 proteins are toxic to Aedes aegypti, the vector of dengue, chikungunya, and Zika viruses. Cry11Aa and Cry11Bb are protoxins, which when activated present their active-toxin form in two fragments between 30 and 35 kDa respectively. Previous studies conducted with Cry11Aa and Cry11Bb genes using DNA shuffling generated variant 8, which presented a deletion in the first 73 amino acids and one at position 572 and 9 substitutions including L553F and L556W. In this study, variant 8 mutants were constructed using site-directed mutagenesis, resulting in conversion of phenylalanine (F) and tryptophan (W) to leucine (L) at positions 553 and 556, respectively, producing the mutants 8F553L, 8W556L, and 8F553L/8W556L. Additionally, two mutants, A92D and C157R, derived from Cry11Bb were also generated. The proteins were expressed in the non-crystal strain BMB171 of Bacillus thuringiensis and subjected to median-lethal concentration (LC50) tests on first-instar larvae of A. aegypti. LC50 analysis showed that the 8F553L, 8W556L, 8F553L/8W556L, and C157R variants lost their toxic activity (>500 ng·mL-1), whereas the A92D protein presented a loss of toxicity of 11.4 times that of Cry11Bb. Cytotoxicity assays performed using variant 8, 8W556L and the controls Cry11Aa, Cry11Bb, and Cry-negative BMB171 on the colorectal cancer cell line SW480 reported 30-50% of cellular viability except for BMB171. Molecular dynamic simulations performed to identify whether the mutations at positions 553 and 556 were related to the stability and rigidity of the functional tertiary structure (domain III) of the Cry11Aa protein and variant 8 showed the importance of these mutations in specific regions for the toxic activity of Cry11 against A. aegypti. This generates pertinent knowledge for the design of Cry11 proteins and their biotechnological applications in vector-borne disease control and cancer cell lines.

BILN: A Human-Readable Line Notation for Complex Peptides.

We present an easy, human-readable line notation to describe even complex peptides.

Protocol for iterative optimization of modified peptides bound to protein targets.

Peptides are commonly used as therapeutic agents. However, they suffer from easy degradation and instability. Replacing natural by non-natural amino acids can avoid these problems, and potentially improve the affinity towards the target protein. Here, we present a computational pipeline to optimize peptides based on adding non-natural amino acids while improving their binding affinity. The workflow is an iterative computational evolution algorithm, inspired by the PARCE protocol, that performs single-point mutations on the peptide sequence using modules from the Rosetta framework. The modifications can be guided based on the structural properties or previous knowledge of the biological system. At each mutation step, the affinity to the protein is estimated by sampling the complex conformations and applying a consensus metric using various open protein-ligand scoring functions. The mutations are accepted based on the score differences, allowing for an iterative optimization of the initial peptide. The sampling/scoring scheme was benchmarked with a set of protein-peptide complexes where experimental affinity values have been reported. In addition, a basic application using a known protein-peptide complex is also provided. The structure- and dynamic-based approach allows users to optimize bound peptides, with the option to personalize the code for further applications. The protocol, called mPARCE, is available at: https://github.com/rochoa85/mPARCE/ .

PepFun: Open Source Protocols for Peptide-Related Computational Analysis.

Peptide research has increased during the last years due to their applications as biomarkers, therapeutic alternatives or as antigenic sub-units in vaccines. The implementation of computational resources have facilitated the identification of novel sequences, the prediction of properties, and the modelling of structures. However, there is still a lack of open source protocols that enable their straightforward analysis. Here, we present PepFun, a compilation of bioinformatics and cheminformatics functionalities that are easy to implement and customize for studying peptides at different levels: sequence, structure and their interactions with proteins. PepFun enables calculating multiple characteristics for massive sets of peptide sequences, and obtaining different structural observables derived from protein-peptide complexes. In addition, random or guided library design of peptide sequences can be customized for screening campaigns. The package has been created under the python language based on built-in functions and methods available in the open source projects BioPython and RDKit. We present two tutorials where we tested peptide binders of the MHC class II and the Granzyme B protease.

An automated protocol for modelling peptide substrates to proteases.

BACKGROUND: Proteases are key drivers in many biological processes, in part due to their specificity towards their substrates. However, depending on the family and molecular function, they can also display substrate promiscuity which can also be essential. Databases compiling specificity matrices derived from experimental assays have provided valuable insights into protease substrate recognition. Despite this, there are still gaps in our knowledge of the structural determinants. Here, we compile a set of protease crystal structures with bound peptide-like ligands to create a protocol for modelling substrates bound to protease structures, and for studying observables associated to the binding recognition. RESULTS: As an application, we modelled a subset of protease-peptide complexes for which experimental cleavage data are available to compare with informational entropies obtained from protease-specificity matrices. The modelled complexes were subjected to conformational sampling using the Backrub method in Rosetta, and multiple observables from the simulations were calculated and compared per peptide position. We found that some of the calculated structural observables, such as the relative accessible surface area and the interaction energy, can help characterize a protease's substrate recognition, giving insights for the potential prediction of novel substrates by combining additional approaches. CONCLUSION: Overall, our approach provides a repository of protease structures with annotated data, and an open source computational protocol to reproduce the modelling and dynamic analysis of the protease-peptide complexes.

Predicting the Affinity of Peptides to Major Histocompatibility Complex Class II by Scoring Molecular Dynamics Simulations.

Predicting the binding affinity of peptides able to interact with major histocompatibility complex (MHC) molecules is a priority for researchers working in the identification of novel vaccines candidates. Most available approaches are based on the analysis of the sequence of peptides of known experimental affinity. However, for MHC class II receptors, these approaches are not very accurate, due to the intrinsic flexibility of the complex. To overcome these limitations, we propose to estimate the binding affinity of peptides bound to an MHC class II by averaging the score of the configurations from finite-temperature molecular dynamics simulations. The score is estimated for 18 different scoring functions, and we explored the optimal manner for combining them. To test the predictions, we considered eight peptides of known binding affinity. We found that six scoring functions correlate with the experimental ranking of the peptides significantly better than the others. We then assessed a set of techniques for combining the scoring functions by linear regression and logistic regression. We obtained a maximum accuracy of 82% for the predicted sign of the binding affinity using a logistic regression with optimized weights. These results are potentially useful to improve the reliability of in silico protocols to design high-affinity binding peptides for MHC class II receptors.

Repurposing of known drugs for leishmaniasis treatment using bioinformatic predictions, in vitro validations and pharmacokinetic simulations.

Leishmaniasis is a neglected tropical disease caused by Leishmania parasites and is associated to more than 1.3 million cases annually. Some of the pharmacological options for treating the disease are pentavalent antimonials, pentamidine, miltefosine, and amphotericin B. However, all are associated with a wide range of adverse effects and contraindications, as well as resistance from the parasite. In the present study, we looked for pharmacological alternatives to treat leishmaniasis, with a focus on drug repurposing. This was done by detecting potential homologs between proteins targeted by approved drugs and proteins of the parasite. The proteins were analyzed using an interaction network, and the drugs were subjected to in vitro evaluations and pharmacokinetics simulations to compare probable plasma concentrations with the effective concentrations detected experimentally. This strategy yielded a list of 33 drugs with potential anti-Leishmania activity, and more than 80 possible protein targets in the parasite. From the drugs tested, two reported high in vitro activity (perphenazine EC50 = 1.2 µg/mL and rifabutin EC50 = 8.5 µg/mL). These results allowed us to propose these drugs as candidates for further in vivo studies and evaluations of the effectiveness on their topical forms.

Anti-Herpetic, Anti-Dengue and Antineoplastic Activities of Simple and Heterocycle-Fused Derivatives of Terpenyl-1,4-Naphthoquinone and 1,4-Anthraquinone.

Quinones are secondary metabolites of higher plants associated with many biological activities, including antiviral effects and cytotoxicity. In this study, the anti-herpetic and anti-dengue evaluation of 27 terpenyl-1,4-naphthoquinone (NQ), 1,4-anthraquinone (AQ) and heterocycle-fused quinone (HetQ) derivatives was done in vitro against Human Herpesvirus (HHV) type 1 and 2, and Dengue virus serotype 2 (DENV-2). The cytotoxicity on HeLa and Jurkat tumor cell lines was also tested. Using plaque forming unit assays, cell viability assays and molecular docking, we found that NQ 4 was the best antiviral compound, while AQ 11 was the most active and selective molecule on the tested tumor cells. NQ 4 showed a fair antiviral activity against Herpesviruses (EC50: <0.4 µg/mL, <1.28 µM) and DENV-2 (1.6 µg/mL, 5.1 µM) on pre-infective stages. Additionally, NQ 4 disrupted the viral attachment of HHV-1 to Vero cells (EC50: 0.12 µg/mL, 0.38 µM) with a very high selectivity index (SI = 1728). The in silico analysis predicted that this quinone could bind to the prefusion form of the E glycoprotein of DENV-2. These findings demonstrate that NQ 4 is a potent and highly selective antiviral compound, while suggesting its ability to prevent Herpes and Dengue infections. Additionally, AQ 11 can be considered of interest as a leader for the design of new anticancer agents.

Assessing the capability of in silico mutation protocols for predicting the finite temperature conformation of amino acids.

Mutation protocols are a key tool in computational biophysics for modelling unknown side chain conformations. In particular, these protocols are used to generate the starting structures for molecular dynamics simulations. The accuracy of the initial side chain and backbone placement is crucial to obtain a stable and quickly converging simulation. In this work, we assessed the performance of several mutation protocols in predicting the most probable conformer observed in finite temperature molecular dynamics simulations for a set of protein-peptide crystals differing only by single-point mutations in the peptide sequence. Our results show that several programs which predict well the crystal conformations fail to predict the most probable finite temperature configuration. Methods relying on backbone-dependent rotamer libraries have, in general, a better performance, but even the best protocol fails in predicting approximately 30% of the mutations.

Search of Allosteric Inhibitors and Associated Proteins of an AKT-like Kinase from Trypanosoma cruzi.

Proteins associated to the PI3K/AKT/mTOR signaling pathway are widely used targets for cancer treatment, and in recent years they have also been evaluated as putative targets in trypanosomatids parasites, such as Trypanosoma cruzi. Here, we performed a virtual screening approach to find candidates that can bind regions on or near the Pleckstrin homology domain of an AKT-like protein in T. cruzi. The compounds were also evaluated in vitro. The in silico and experimental results allowed us to identify a set of compounds that can potentially alter the intracellular signaling pathway through the AKT-like kinase of the parasite; among them, a derivative of the pyrazolopyridine nucleus with an IC50 of 14.25 ± 1.00 µM against amastigotes of T. cruzi. In addition, we built a protein⁻protein interaction network of T. cruzi to understand the role of the AKT-like protein in the parasite, and look for additional proteins that can be postulated as possible novel molecular targets for the rational design of compounds against T. cruzi.

Drug search for leishmaniasis: a virtual screening approach by grid computing.

The trypanosomatid protozoa Leishmania is endemic in ~100 countries, with infections causing ~2 million new cases of leishmaniasis annually. Disease symptoms can include severe skin and mucosal ulcers, fever, anemia, splenomegaly, and death. Unfortunately, therapeutics approved to treat leishmaniasis are associated with potentially severe side effects, including death. Furthermore, drug-resistant Leishmania parasites have developed in most endemic countries. To address an urgent need for new, safe and inexpensive anti-leishmanial drugs, we utilized the IBM World Community Grid to complete computer-based drug discovery screens (Drug Search for Leishmaniasis) using unique leishmanial proteins and a database of 600,000 drug-like small molecules. Protein structures from different Leishmania species were selected for molecular dynamics (MD) simulations, and a series of conformational "snapshots" were chosen from each MD trajectory to simulate the protein's flexibility. A Relaxed Complex Scheme methodology was used to screen ~2000 MD conformations against the small molecule database, producing >1 billion protein-ligand structures. For each protein target, a binding spectrum was calculated to identify compounds predicted to bind with highest average affinity to all protein conformations. Significantly, four different Leishmania protein targets were predicted to strongly bind small molecules, with the strongest binding interactions predicted to occur for dihydroorotate dehydrogenase (LmDHODH; PDB:3MJY). A number of predicted tight-binding LmDHODH inhibitors were tested in vitro and potent selective inhibitors of Leishmania panamensis were identified. These promising small molecules are suitable for further development using iterative structure-based optimization and in vitro/in vivo validation assays.

A novel pathogenic variant in PRF1 associated with hemophagocytic lymphohistiocytosis.

Familial Hemophagocytic Lymphohistiocytosis type 2 (FHL2) results from mutations in PRF1. We described two unrelated individuals who presented with FHL, in whom severely impaired NK cytotoxicity and decrease perforin expression was observed. DNA sequencing of PRF1 demonstrated that both were not only heterozygous for the p.54R > C/91A > V haplotype but also presented with the novel variant p.47G > V at the perforin protein. Perforin mRNA was found to be increased in a individual with that genotype. A carrier of the novel variant also demonstrated altered perforin mRNA and protein expression. Phylogenetic analysis and multiple alignments with perforin orthologous demonstrated a high level of conservation at Gly47. PolyPhen-2 and PROVEAN predicted p.47G > V to be "probably damaging" and "deleterious", respectively. A thermodynamic analysis showed that this variant was highly stabilizing, decreasing the protein internal energy. The ab initio perforin molecular modeling indicated that Gly47 is buried inside the hydrophobic core of the MACPF domain, which is crucial for the lytic pore formation and protein oligomerization. After the in silico induction of the p.47G > V mutation, Val47 increased the interactions with the surrounding amino acids due to its size and physical properties, avoiding a proper conformational change of the domain. To our knowledge, this is the first description supporting that p.47G > V is a pathogenic variant that in conjunction with p.54R > C/91A > V might result in the clinical phenotype of FHL2.

myChEMBL: a virtual machine implementation of open data and cheminformatics tools.

UNLABELLED: myChEMBL is a completely open platform, which combines public domain bioactivity data with open source database and cheminformatics technologies. myChEMBL consists of a Linux (Ubuntu) Virtual Machine featuring a PostgreSQL schema with the latest version of the ChEMBL database, as well as the latest RDKit cheminformatics libraries. In addition, a self-contained web interface is available, which can be modified and improved according to user specifications. AVAILABILITY AND IMPLEMENTATION: The VM is available at: ftp://ftp.ebi.ac.uk/pub/databases/chembl/VM/myChEMBL/current. The web interface and web services code is available at: https://github.com/rochoa85/myChEMBL.

Patients with ankylosing spondylitis and low disease activity because of anti-TNF-alpha therapy have higher TRAIL levels than controls: a potential compensatory effect.

OBJECTIVE: TRAIL is a potential biomarker of cardiovascular (CV) disease. Ankylosing spondylitis (AS) is a chronic inflammatory disease associated with metabolic syndrome (MeS) and accelerated atherosclerosis. We assessed whether disease activity, systemic inflammation, and MeS features were associated with circulating TRAIL levels in AS patients undergoing TNF-α antagonist infliximab therapy and if infliximab infusion modified TRAIL levels. METHODS: We measured TRAIL serum levels in 30 nondiabetic AS patients without CV disease undergoing anti-TNF-α therapy, immediately before and after an infliximab infusion, and in 48 matched controls. Correlations of TRAIL levels with disease activity, systemic inflammation and MeS features, adipokines, and biomarkers of endothelial activation were evaluated. Changes in TRAIL levels following anti-TNF-α infusion were analyzed. RESULTS: TRAIL levels were higher in AS patients than controls. TRAIL levels displayed an inverse correlation with total and LDL cholesterol. We observed an inverse correlation with QUICKI and a marginal association with HOMA-IR. We also found an inverse correlation with resistin and a marginal association with apelin and OPN. Anti-TNF-α infusion did not change TRAIL levels after 120'. CONCLUSION: Elevated TRAIL levels in AS patients may be the result of a compensatory mechanism to reduce CV risk in these patients.

Leptin and visfatin serum levels in non-diabetic ankylosing spondylitis patients undergoing TNF-α antagonist therapy.

OBJECTIVES: This paper aims to determine whether disease activity, systemic inflammation and metabolic syndrome are potential determinants of circulating leptin and visfatin levels in ankylosing spondylitis (AS) patients undergoing TNF-α antagonist therapy. We also assessed whether the infusion of infliximab may alter circulating leptin and visfatin concentrations in these patients. METHODS: We investigated leptin and visfatin serum concentrations in a series of 30 non-diabetic AS patients without history of cardiovascular (CV) events that were treated with the TNF-α antagonist infliximab, immediately prior to an infliximab infusion. Leptin and visfatin levels were also determined immediately after administration of an infliximab dose. RESULTS: Significant differences in leptin concentrations between men (8.85±5.31 ng/ml) and women (18.96±9.72 ng/ml) were observed (p=0.001). A significant correlation between visfatin concentrations and insulin resistance (HOMA at the time of the study) was found (r= 0.493; p=0.009). Circulating leptin and visfatin concentrations did not correlate with disease duration, erythrocyte sedimentation rate, C-reactive protein, BASDAI and VAS at the time of the study and adiponectin and resistin levels prior to infliximab infusion. Likewise, no differences in leptin and visfatin concentrations were observed when patients with a history of anterior uveitis or presence of syndesmophytes were compared with the remaining patients who did not exhibit these features. Leptin and visfatin levels did not change upon infliximab administration. CONCLUSIONS: The present study indicates that in non-diabetic patients with AS on treatment with infliximab leptin and visfatin serum levels do not correlate with disease activity or systemic inflammation. Nevertheless, visfatin concentration correlates with insulin resistance.

Apelin serum levels in non-diabetic ankylosing spondylitis patients undergoing TNF-α antagonist therapy.

OBJECTIVES: To determine whether disease activity, systemic inflammation and metabolic syndrome are potential determinants of circulating apelin in ankylosing spondylitis (AS) patients undergoing TNF-α antagonist-infliximab therapy. METHODS: We investigated apelin serum concentrations in a series of 30 non-diabetic AS patients without history of cardiovascular (CV) events that were treated with the TNF-α antagonist infliximab, immediately prior to an infliximab infusion. Correlations of apelin serum levels with disease activity, systemic inflammation and metabolic syndrome were assessed. Also, potential changes in apelin concentration following an infusion of the anti-TNF-α monoclonal antibody-infliximab were analysed. RESULTS: No significant correlation between apelin concentration and demographic features, inflammation, adiposity and metabolic syndrome features was seen. Neither differences were seen in basal apelin in different categorical variables associated to AS. Following infliximab infusion, a reduction of apelin serum levels was observed. In this regard, the median (interquartile range) values of apelin decreased from 0.99 (0.74-1.25) ng/ml immediately prior to infliximab infusion to 0.92 (0.72-1.39) ng/ml at the end of the infusion (time 120 minutes). However, the reduction in apelin serum levels following administration of the drug did not achieve statistical significance. CONCLUSIONS: The present study shows that in non-diabetic patients with AS on treatment with infliximab apelin serum levels do not correlate with disease activity or metabolic syndrome. A single infusion of infliximab does not yield a significant change of apelin serum levels in AS patients.

Adiponectin and resistin serum levels in non-diabetic ankylosing spondylitis patients undergoing TNF-α antagonist therapy.

OBJECTIVES: The objective of this paper is to assess if disease activity, systemic inflammation and metabolic syndrome are potential determinants of circulating adiponectin and resistin levels in ankylosing spondylitis (AS) patients undergoing TNF-α antagonist therapy. METHODS: We investigated adiponectin and resistin serum concentrations in a series of 29 non-diabetic AS patients without history of cardiovascular (CV) events that were treated with the TNF-α antagonist infliximab, immediately prior to an infliximab infusion. Adipokine levels were also determined immediately after administration of an infliximab dose. RESULTS: A significant correlation between adiponectin concentrations and insulin sensitivity (QUICKI at the time of the study) was seen (r=0.384; p=0.05). Also, a marginally significant negative correlation between adiponectin serum levels and the body mass index was observed (r=-0.367; p=0.07). Circulating adiponectin and resistin concentrations did not correlate with disease duration, erythrocyte sedimentation rate, C-reactive protein, BASDAI or VAS at the time of the study. However, AS patients with hip involvement or synovitis and/or enthesitis in other peripheral joints had higher adiponectin concentrations than those who did not have these complications (p-value for both comparisons =0.01). Adiponectin and resistin levels did not change upon infliximab administration. CONCLUSIONS: The present study shows that in non-diabetic patients with AS on treatment with infliximab adiponectin and resistin serum levels do not correlate with disease activity. Nevertheless, adiponectin concentration correlates with insulin sensitivity. This finding raises the possibility that low circulating adiponectin concentrations may be involved in the pathogenesis of the CV disease in AS.

Angiopoietin-2 serum levels correlate with severity, early onset and cardiovascular disease in patients with rheumatoid arthritis.

OBJECTIVES: Rheumatoid arthritis (RA) is an inflammatory disease associated with accelerated atherosclerosis and high risk of cardiovascular (CV) disease. Angiopoietin-2 (Angpt-2), a marker of endothelial cell activation, has been proposed as a mediator of angiogenesis, which might play an important role in the regulation of endothelial integrity and inflammation. Therefore, the aim of this study was to determine whether Angpt-2 is related to severity and CV disease in RA patients. METHODS: Angpt-2 serum levels were measured by enzyme linked immunosorbent assay (ELISA) in 290 patients with RA. A control group of 100 individuals frequency matched by age and sex and classic CV risk factors and CV disease was also assessed. RESULTS: Eighty-four patients with RA (28.9%) had experienced CV events. Also, extra-articular manifestations were present in 41 (14%) of these patients. Although there were not significant differences between patients and controls, a correlation between age at the time of disease onset and Angpt-2 was observed in RA patients (r=-0.31; p=0.02). Angpt-2 serum levels also correlated positively with extra-articular disease (mean±standard deviation in RA patients with and without extra-articular manifestations were 2476±1716 pg/ml and 1897±1228 pg/ml, respectively; p=0.01). Moreover, after adjustment for sex, age at RA diagnosis and CV risk factors, Angpt-2 levels were higher in RA patients with CV disease than in RA patients without CV complications (2472±1826 pg/ml vs. 1875±1101 pg/ml; p=0.05). Angpt-2 serum levels remained significantly higher in RA patients with CV disease compared to those without CV disease after additional adjustment for extra-articular manifestations (p=0.04). CONCLUSIONS: Our results show that Angpt-2 serum levels correlate with disease severity, early onset and CV disease in RA patients.

Correlation between insulin resistance and serum ghrelin in non-diabetic ankylosing spondylitis patients undergoing anti-TNF-α therapy.

OBJECTIVES: To evaluate whether anti-TNF-α therapy (infliximab) administration alters circulating levels of ghrelin, an anti-inflammatory gastric peptide. We also assessed possible associations of circulating ghrelin concentrations with CRP and ESR levels, metabolic syndrome, demographic characteristics and other adipokines in ankylosing spondylitis (AS) patients. METHODS: We studied 30 consecutive non-diabetic AS patients, without history of cardiovascular (CV) events, on periodical treatment with infliximab. Serum ghrelin levels were determined immediately prior to and after an infliximab infusion. Correlations of ghrelin serum levels with disease activity, systemic inflammation and metabolic syndrome were assessed. Potential changes in ghrelin concentration following an infusion of infliximab were analysed. RESULTS: We observed a negative correlation between ghrelin concentration and insulin resistance (HOMA-IR immediately before infliximab infusion- at time 0 and at the end of infliximab infusion- at time 120') (r=-0.496; p=0.01 at time 0; r=-0.393; p=0.047 at time 120', respectively). We also found a positive correlation with insulin sensitivity (QUICKI) (r=0.415; p=0.035 at time 0; r=0.465; p=0.017 at time 120'). A correlation was found between ghrelin and resistin prior to infliximab infusion (r=0.429; p=0.046), and a negative correlation between serum ghrelin levels at time 0 and triglycerides (r=-0.416; p=0.035). No differences in ghrelin levels according to specific clinical features of the disease were seen. A single infliximab infusion led to mild but not significant increase in ghrelin serum concentration. CONCLUSIONS: In AS patients undergoing periodical treatment with anti-TNF-α monoclonal antibody-infliximab a link between insulin resistance and serum ghrelin concentration was observed.