Overexpression of TLR7 and TLR9 Occurs Before Onset Symptoms In First-Degree Relatives of Rheumatoid Arthritis Patients.

BACKGROUND: Autoantibodies have a central role in the physiopathology of Rheumatoid Arthritis (RA). However, the responsible factors that trigger and perpetuate the autoantibodies production are unknown. Toll-like receptors (TLRs) have been considered as promotors of autoantibodies production to break down the immunotolerance in RA. AIM OF THE STUDY: Evaluate the expression levels of TLR7 and TLR9 as well as their correlation with autoantibodies in first-degree relatives (FDR) of RA patients (seropositive and seronegative to ACPA), respect to early RA (eRA) and chronic RA (cRA) patients. METHODS: We selected 32 RA patients (16 as eRA and 16 as cRA) and 32 FDR of RA patients (16 seropositive and 16 seronegative to ACPA). Expression levels of TLR7 and TLR9 in whole blood samples from each group were measured by real-time PCR using total RNA extracted from each subject. Also, correlation analysis between TLRs expression and autoantibodies was performed. RESULTS: The expression of TLR7 and TLR9 was diminished in RA patients (p <0.01) but elevated in ACPA- FDR (p <0.0001) and ACPA+ FDR (p <0.05) with a positive correlation between them (r = 0.749, p <0.000). Moreover, the expression levels of TLR7 correlate positively with ACPA levels in both seropositive ACPA+ FDR subjects (r = 0.582, p = 0.018) and eRA patients (r = 0.593, p = 0.020). CONCLUSIONS: Our results showed overexpression of TLR7 and TLR9 may occur in preclinical RA subjects. TLR7 overexpression correlated with ACPA levels' production, suggesting TLR7 may play a role in ACPA development.

Calpain Participates in Cortical Cytoskeleton Modification and DNA Release during Neutrophil Extracellular Trap Formation.

INTRODUCTION: The formation of neutrophil extracellular traps (NETs) is a process in which several kinds of enzymes participate generating posttranslational modifications of proteins. NETs have been associated with infectious, autoimmune, and inflammatory diseases. Inhibition of several proteases reduces the formation of NETs. In the present work, we analyzed the role of several broad-acting and specific inhibitors of proteases in the formation of NETs. METHODS: Neutrophils were isolated from peripheral blood of healthy individuals by density gradient. The neutrophils were quantified and seeded into cell culture plates. Phorbol myristate acetate and A23187 were used as NETs inducers, and several specific inhibitors of proteases were used. The cells were stained for cytoskeleton or DNA. The cell-free supernatants were used to assess DNA release. Statistical analysis was carried out by a Kruskal-Wallis or ANOVA test. RESULTS: We observed marked changes in actin organization after the induction of NETs, suggesting that the cytoskeleton is being actively regulated. When we used protease inhibitors, the release of DNA was reduced, suggesting the participation of actin remodeling in the process. Further characterization of the specific proteases revealed that calpain modulates the reorganization of actin cytoskeleton and DNA release. Preservation of part of the actin cytoskeleton suggests that DNA release is not only a mechanic process associated to the chromatin decondensation; rather the process is highly regulated by active proteases that promote cytoskeleton reorganization and chromatin decondensation that culminates in DNA release. CONCLUSION: Calpain mediates the DNA release in the NET formation process by the modification of cortical actin cytoskeleton in a calcium-dependent manner.

Subclinical inflammation in the preclinical phase of rheumatoid arthritis might contribute to articular joint damage.

The first degree relatives of rheumatoid arthritis (RA) patients have a higher risk of developing RA, which is related to the expression of autoantibodies against citrullinated proteins (ACPA). Remarkably, prior to the onset of RA, cartilage damage is already initiated, whereas ACPA autoantibodies are already expressed. Here we show that both TNF-α and IL-6 are also increased prior to the onset of RA. Furthermore, when the levels of DKK1 and Sclerostin were evaluated in first degree relatives of RA patients, we found that the serum levels of TNF- α correlate with the expression levels of both DKK1 and Sclerostin. Interestingly, when the disease is already established, the correlation of TNF- α with DKK1 is lost in RA patients, whereas the correlation of Sclerostin with both TNF- α and IL-6 is further increased. Our data suggest a subclinical inflammation in patients at high risk of developing RA, which might lead to an increase in the levels of both DKK1 and Sclerostin, contributing to joint damage in the preclinical phase of the disease linked to the expression of ACPA autoantibodies.

Expression and activity of AIM2-inflammasome in rheumatoid arthritis patients.

INTRODUCTION: AIM2 inflammasome activation leads to the release of IL-ß, which plays an important role in rheumatoid arthritis pathogenesis. In this work, we evaluated AIM2 expression and activity in RA patients and healthy controls. METHODS: AIM2 and RANKL expression were evaluated by flow cytometry. Inflammasome activity was determined in monocyte cultures stimulated with synthetic DNA by measuring IL-1ß levels in supernatants using an ELISA assay. The caspase-1 expression in monocytes was measured by western blot, the POP3 expression was analysed by qPCR, and serum levels of IFN-γ were evaluated using ELISA assay. RESULTS: We observed a diminution of CD14+AIM2+ cells in RA patients, associated with disease activity and evolution. Likewise, the levels of IL-1ß were increased in monocyte cultures un-stimulated and stimulated with LPS from RA patients with DAS28 ≥ 4. The Caspase-1 activity and RANKL + monocytes in RA patients were slightly increased. Finally, augmented POP3 expression and diminished IFN-γ serum levels were detected in RA patients. CONCLUSION: Our results showed that the monocytes from RA patients were prone to release IL-1ß in the absence of the AIM2 inflammasome signal. The down-regulation of AIM2 to a systemic level in RA patients might be a consequence of augmented POP3 expression and might imply the survival of pro-inflammatory cells contributing to the inflammation process.

Blockade of the dopaminergic neurotransmission with AMPT and reserpine induces a differential expression of genes of the dopaminergic phenotype in substantia nigra.

Dopaminergic neurons have the ability to release Dopamine from their axons as well as from their soma and dendrites. This somatodendritically-released Dopamine induces an autoinhibition of Dopaminergic neurons mediated by D2 autoreceptors, and the stimulation of neighbor GABAergic neurons mediated by D1 receptors (D1r). Here, our results suggest that the somatodendritic release of Dopamine in the substantia nigra (SN) may stimulate GABAergic neurons that project their axons into the hippocampus. Using semiquantitative multiplex RT-PCR we show that chronic blockade of the Dopaminergic neurotransmission with both AMPT and reserpine specifically decreases the expression levels of D1r, remarkably this may be the result of an antagonistic effect between AMPT and reserpine, as they induced the expression of a different set of genes when treated by separate. Furthermore, using anterograde and retrograde tracing techniques, we found that the GABAergic neurons that express D1r also project their axons in to the CA1 region of the hippocampus. Finally, we also found that the same treatment that decreases the expression levels of D1r in SN, also induces an impairment in the performance in an appetitive learning task that requires the coding of reward as well as navigational skills. Overall, our findings show the presence of a GABAergic interconnection between the SNr and the hippocampus mediated by D1r.

Evaluation of SUMO1 and POU2AF1 in whole blood from rheumatoid arthritis patients and at risk relatives.

Rheumatoid arthritis (RA) is a systemic autoimmune disorder characterized by chronic and symmetrical inflammation of synovial tissue with subsequent joint destruction. SUMO1 is an important regulator of apoptosis through non-canonical mechanism in synovial fibroblasts, and POU2AF1 is a known B-cell transcriptional co-activator. The specific objective of this study was to measure the expression of SUMO1 and POU2AF1 on first-degree relatives of patients with RA and also in the preclinical and clinical stages of RA and describe their possible role in RA physiopathology. Blood samples were collected from ACPA+, ACPA-, early and established RA subjects recruited. ACPAs and CarP autoantibodies were determined by ELISA Eurodiagnostica CCplus kit according to previously described protocols. RNA was isolated from blood samples; the purity as integrity was determined. Gene expression analysis was made by RT-qPCR using specific primers for SUMO1 and POU2AF1 mRNAs; relative expression was determined according to the 2-ΔΔct method procedure. Significant differences in the expression of both, SUMO1 and POU2AF1 were identified when comparing arthritis versus healthy or ACPA+ individuals, suggesting that the down regulation of such genes starts after the onset of symptoms in RA patients. Also, a significant correlation was identified for POU2AF1 and disease progression whit a downward trend for those with established RA. The implications of such gene down regulation are discussed in the context of RA physiopathology.

AMPA receptors modulate the reorganization of F-actin in Bergmann glia cells through the activation of RhoA.

Alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid glutamate receptors have been shown to modulate the morphology of the lamelar processes of Bergmann glia cells in the molecular layer of the cerebellum. Here we suggest that reorganization of F-actin may underlay the changes in the morphology of the lamelar processes. Using the fluorescent staining of F-actin with Phalloidin and the quantification of RhoA activation through immunoprecipitation or pull-down assays, we show that RhoA is activated after stimulation of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptors and leads to the reorganization of the actin cytoskeleton of Bergmann fibers. This reorganization of the actin cytoskeleton is reflected in the form of an increase in the intensity of the F-actin staining as well as in the loss of the number of Bergmann fibers stained with Phalloidin. Moreover, using a pharmacological approach, we show that activation of RhoA and the change in the intensity of the F-actin staining depends on the activation of PI3-K, focal adhesion kinase, and protein kinase C, whereas changes in the number of Bergmann fibers depend on external calcium in a RhoA independent manner. Our findings show that glutamate may induce a form of structural plasticity in Bergmann glia cells through the reorganization of the actin cytoskeleton. This may have implications in the way the synaptic transmission is processed in the cerebellum.

Analysis of miRNA expression in patients with rheumatoid arthritis during remission and relapse after a 5-year trial of tofacitinib treatment.

The physiopathology of rheumatoid arthritis (RA) is mediated by proinflammatory cytokines, some of which are regulated by the JAK/STAT pathway. Tofacitinib is a JAK inhibitor, but its role in the regulation of microRNAs (miRNAs) is unknown. There is also no information regarding the role of miRNAs in the clinical relapse/remission of RA. The present project aims to identify a signature profile of miRNA expression in a subgroup of RA patients who had to discontinue tofacitinib treatment (because of the ending of a 5-year open-label clinical trial) and to describe the expression of miRNAs during RA remission or flare-up. The relative expression of 61 miRNAs was determined in serum samples with the Firefly™ BioWorks assay. Statistical analysis was performed by means of Student's t-test and heatmap analysis was performed with Firefly™ Analysis Workbench software and in the software GraphPad® Prism v5.0. Target prediction and Gene Ontology analysis were carried out using bioinformatic tools. We found a distinctive signature of miRNA expression associated with relapse, featuring upregulated expression of hsa­miR­432­5p (p < 0.05). We also found upregulation of hsa­miR­194­5p (p < 0.05) in samples of patients with RA flare-up. Gene Ontology analysis of the target genes for hsa­miR­432­5p was performed to identify relevant pathways associated with relapse; the implications of these pathways in the physiopathology of RA are discussed. Tofacitinib treatment does not have a direct effect on the expression of measured miRNAs. The changes in hsa­miR­432­5p and hsa­miR­194­5p are associated with the regulation of proinflammatory pathways and RA flare-up.

Improvement in the Diagnosis of Tuberculosis Combining Mycobacterium Tuberculosis Immunodominant Peptides and Serum Host Biomarkers.

BACKGROUND: Pulmonary tuberculosis (PTB) is a public health problem with 10.4 million new cases reported in 2017 (1). According to the World Health Organization (WHO), accurate diagnostic tests based in serum biomarkers to detect new cases of tuberculosis are necessary. AIM OF THE STUDY: To evaluate antibodies against Mycobacterium. tuberculosis (Mtb) peptides (Ab-Mtb) and three soluble host biomarkers by ELISA serial multiple test in sera from non-infected controls (NIC, n = 31), latent tuberculosis (LTB, n = 37) and PTB (n = 28) patients in a diagnosis tuberculosis assay. MATERIALS AND METHODS: Levels of four Ab-Mtb peptides derived from Mtb and three host response molecules in serum from NIC, LTB and PTB were evaluated by ELISA as tuberculosis biomarkers. Multiple comparisons tests, determination of diagnostic values and ROC curves were performed. Serial and parallel multiple tests were performed with the biomarkers with the highest discriminatory capacity to improve diagnostic values of the test. RESULTS: We found significant differences between biomarkers levels in PTB comparing LTB and NIC to all candidate biomarkers; peptides P12033, P12037, and serum biomarkers such as sCD14 and chemokine CXCL9 showed the best sensitivity and specificity, the highest discriminatory power, and the best area under the curve (AUC) individually. In serial multiple tests, P12037 and sCD14 together have 92% of sensitivity and 91% of specificity, with positive and negative likelihood ratios greater than 10. CONCLUSIONS: Ab-Mtb peptide P12037 and sCD14 could be applied in a diagnostic test for suspected PTB to improve accuracy and time to diagnosis and could be implemented in a POCT device which can be affordable.

ADAM15 participates in fertilization through a physical interaction with acrogranin.

Mammalian fertilization is completed by direct interaction between sperm and egg. This process is primarily mediated by both adhesion and membrane-fusion proteins found on the gamete surface. ADAM1, 2, and 3 are members of the ADAMs protein family, and have been involved in sperm-egg binding. In this study, we demonstrate the proteolytic processing of ADAM15 during epididymal maturation of guinea pig spermatozoa to produce a mature form a size of 45 kDa. We find that the size of the mature ADAM15, 45 kDa, in cauda epididymal spermatozoa indicates that the pro-domain and metalloprotease domain are absent. In addition, using indirect immunofluorescence, ADAM15 was found throughout the acrosome, at the equatorial region and along the flagellum of guinea pig spermatozoa. After acrosome reaction, ADAM15 is lost from the acrosomal region and retained in the equatorial region and flagellum. In this study, we also report the first evidence of a complex between ADAM15 and acrogranin. By immunoprecipitation, we detected a protein band of 65 kDa which co-immunoprecipated together ADAM15. Analysis of the N-terminal sequence of this 65 kDa protein has revealed its identity as acrogranin. In addition, using cell-surface labeling, ADAM15 was found to be present on the cell surface. Assays of heterologous fertilization showed that the antibody against acrogranin inhibited the sperm-egg adhesion. Interestingly, ADAM15 and acrogranin were also found associated in two breast cancer cell lines. In conclusion, our results demonstrated that ADAM15 and acrogranin are present on and associated with the surface of guinea pig spermatozoa; besides both proteins may play a role during sperm-egg binding.

Calpain modulates capacitation and acrosome reaction through cleavage of the spectrin cytoskeleton.

Research on fertilization in mammalian species has revealed that Ca(2+) is an important player in biochemical and physiological events enabling the sperm to penetrate the oocyte. Ca(2+) is a signal transducer that particularly mediates capacitation and acrosome reaction (AR). Before becoming fertilization competent, sperm must experience several molecular, biochemical, and physiological changes where Ca(2+) plays a pivotal role. Calpain-1 and calpain-2 are Ca(2+)-dependent proteases widely studied in mammalian sperm; they have been involved in capacitation and AR but little is known about their mechanism. In this work, we establish the association of calpastatin with calpain-1 and the changes undergone by this complex during capacitation in guinea pig sperm. We found that calpain-1 is relocated and translocated from cytoplasm to plasma membrane (PM) during capacitation, where it could cleave spectrin, one of the proteins of the PM-associated cytoskeleton, and facilitates AR. The aforementioned results were dependent on the calpastatin phosphorylation and the presence of extracellular Ca(2+). Our findings underline the contribution of the sperm cytoskeleton in the regulation of both capacitation and AR. In addition, our findings also reveal one of the mechanisms by which calpain and calcium exert its function in sperm.

In spermatozoa, Stat1 is activated during capacitation and the acrosomal reaction.

A role for sperm-specific proteins during the early embryonic development has been suggested by a number of recent studies. However, little is known about the participation of transcription factors in that stage. Here, we show that the signal transducer and activator of transcription 1 (Stat1), but not Stat4, was phosphorylated in response to capacitation and the acrosomal reaction (AR). Moreover, Stat1 phosphorylation correlated with changes in its localization: during capacitation, Stat1 moved from the cytoplasm to the theca/flagellum fraction. During AR, Stat1 phosphorylation increased again. In addition, blocking protein kinase A (PKA) and PKC during capacitation abolished both phosphorylation and migration of Stat1. Our results show tight spatio-temporal rearrangements of Stat1, suggesting that after fertilization Stat1 participates in the first rounds of transcription within the male pronucleus.