Thromboxane A2 acts as tonic immunoregulator by preferential disruption of low-avidity CD4+ T cell–dendritic cell interactions

Interactions between dendritic cells (DCs) and T cells control the decision between activation and tolerance induction. Thromboxane A2 (TXA2) and its receptor TP have been suggested to regulate adaptive immune responses through control of T cell–DC interactions. Here, we show that this control is achieved by selectively reducing expansion of low-avidity CD4⁺ T cells. During inflammation, weak tetramer-binding TP-deficient CD4⁺ T cells were preferentially expanded compared with TP-proficient CD4⁺ T cells. Using intravital imaging of cellular interactions in reactive peripheral lymph nodes (PLNs), we found that TXA2 led to disruption of low- but not high-avidity interactions between DCs and CD4⁺ T cells. Lack of TP correlated with higher expression of activation markers on stimulated CD4⁺ T cells and with augmented accumulation of follicular helper T cells (T_FH), which correlated with increased low-avidity IgG responses. In sum, our data suggest that tonic suppression of weak CD4⁺ T cell–DC interactions by TXA2–TP signaling improves the overall quality of adaptive immune responses.T cells have evolved to quickly react to potentially dangerous microbes by recognizing pathogen-derived peptide (p)-MHC complexes displayed on antigen-presenting cells, in particular DCs. Because T cells are selected in the thymus for their ability to recognize self-pMHC complexes (Morris and Allen, 2012) and numerous self-reactive T cells are released into the periphery (Su et al., 2013), peripheral tolerance education is critical to avoid activation of autoreactive T cells. Studies using intravital two-photon microscopy (2PM) of reactive PLNs have shed light on the dynamic T cell–DC interactions and their correlation with full versus curtailed T cell activation and tolerance induction. The amount of cognate pMHC complexes on activated DCs is critical in determining the transition of a highly motile scanning-mode T cell to an immotile, stably interacting one (Cahalan and Parker, 2006; Henrickson and von Andrian, 2007; Bajénoff and Germain, 2007). Such stable T cell–DC interactions (>8h) are a prerequisite for full effector T cell differentiation (Rachmilewitz and Lanzavecchia, 2002). Thus, in presence of high amounts of cognate pMHC on activated DCs, T cells decelerate rapidly, whereas T cells show a motile DC sampling behavior when cognate pMHC levels are low. Altered peptide ligands (APLs) with reduced affinity for a given TCR also decrease the length of T cell–DC interactions, limiting T cell activation. Under tolerogenic conditions (i.e., in the absence of co-stimulation), 2PM studies uncovered shortened T cell–DC interactions (Hugues et al., 2004) although this is still controversial (Shakhar et al., 2005). Similarly, the presence of regulatory T (T reg) cells reduces T cell–DC interactions and subsequent T cell activation (Tadokoro et al., 2006; Tang et al., 2006).A perhaps counterintuitive recent finding has revealed a significant increase in CD8⁺ T cell immune response avidity in presence of T reg cells (Pace et al., 2012). This is due to T reg cell–mediated suppression of excessive interactions between DCs and CD8⁺ T cells bearing TCRs with low avidity for pMHC complexes. In the absence of T reg cells, uncontrolled CCR5 ligand secretion by activated DCs induces attraction of bystander TCR clones with low affinity for pMHC complexes, which decreases overall avidity and memory T cell generation of the resulting immune response. Whether a comparable mechanism also exists to selectively support activation of high avidity CD4⁺ T cells by immunoregulatory factors is currently unknown.The short-lived arachidonic acid–derived lipid thromboxane A2 (TXA2) has been suggested to regulate adaptive immune responses (Kabashima et al., 2003). Activated DCs and other cell types produce TXA2, which binds its G-protein coupled receptor TP expressed in thymocytes and naive but not effector/memory CD4⁺ and CD8⁺ T cells. Addition of high amounts of the TP agonist I-BOP induces chemokinesis in naive T cells and decreases in vitro aggregate formation between T cells and DCs, causing reduced T cell activation (Kabashima et al., 2003). Combined with the observation that TXA2 levels rapidly rise in reactive PLN during immune responses (Moore et al., 1989), these data suggest a model where TXA2 may act as a general suppressor of T cell–DC interactions. In line with this hypothesis, aged TP-deficient T cells develop lymphoid hyperplasia and high antibody titers (Kabashima et al., 2003). Yet, it has remained unknown how TXA2 signaling affects dynamic CD4⁺ T cell interactions with DC displaying varying pMHC abundance and affinity in vivo, and how this impacts avidity patterns of responding T cells.Here, we show that during sterile and microbial inflammation, absence of TP resulted in increased expansion of low-avidity CD4⁺ T cells. Using 2PM imaging of cellular interactions in reactive PLNs, we report that paracrine TXA2 signaling preferentially disrupted low-avidity interactions between DCs and OT-II CD4⁺ T cells induced by low cognate pMHC levels or low-affinity peptide. As a consequence, TP^−/− OT-II CD4⁺ T cells show increased expression of early activation markers, as well as augmented accumulation of follicular helper T cells (T_FH) compared with WT OT-II CD4⁺ cells. High numbers of TP^−/− T_FH correlated with increased low-avidity IgG production, thus thwarting the overall quality of the adaptive immune response. In sum, our data uncover a previously unappreciated contribution of a tolerance-inducing mechanism for preferential activation of high avidity CD4⁺ T cells.     

Treatment outcome of HAART-treated patients in a resource-limited setting: The Belgrade Cohort Study

Introduction

We evaluated the effects of highly-active-antiretroviral-therapy (HAART) in a resource-limited settings.

Methods

A cross-sectional study was performed in patients who had initiated HAART at the HIV/AIDS-Center, Belgrade, Serbia. Treatment response was considered favorable in case of the achievement of undetectable HIVRNA plasma-viral-load (pVL < 50 copies/μL), and with the CD4+ T-cell counts increased above 350 cells/μL. The treatment failure was defined as pVL over 1.7 log₁₀ copies/mL, regardless of immunological improvement.

Results

Eight hundred and forty HIV infected patients were followed-up for 8.2 ± 3.4 years. Out of 697 patients available for follow-up, 113 (16.2%) patients died, 44 (6.3%) experienced treatment failure, while 540 (77.5%) had sustained undetectable viremia. In 419 (60.1%) favorable treatment response was achieved, while the dissociation between immunological and virological responses to HAART occurred in 121 (14.4%). A baseline CD4+ T-cell counts above 200 cells/μL was the single independent predictor of a favorable treatment response (HR = 2, 95%CI = 1.69–2.61, P = 0.001), while pre-treatment with ART, HCV co-infection and AIDS at the time of treatment initiation, were all factors preventing a favorable response (HR = 0.27, 95%CI = 0.19–0.36, P = 0.001; HR = 0.75, 95%CI = 0.56–0.95, P = 0.02; HR = 0.73, 95%CI = 0.17–0.95, P = 0.018, respectively). A sustained viral suppression was an independent predictor of survival (HR = 0.2, 95% CI 0.07–0.61, P = 0.004). HAART treated HIV-infected patients who reach and maintain undetectable viremia, have an 80% probability of a 14-years survival (P = 0.08, log-rank).

Conclusion

If patient with advanced HIV-related immunodeficiency reach and maintain optimal viral suppression during HAART, regardless of the level of immune recovery, and if they continue to maintain this, their prognosis may be fairly good even in the resource-limited settings.     

Impact of the mouth breathing occurred during childhood in the adult age: biophotogrammetric postural analysis

Objective

This study aims to evaluate the impact of the mouth breathing occurred during childhood on the body posture in the adult age.

Methods

24 adults, of both genders, aged from 18 to 30 years old with report of clinical manifestations of mouth breathing during the childhood composed the study group (SG). The control group (CG) was composed by 20 adults in the same age, without any respiratory problem since the childhood up to the present time. All the volunteers underwent a physiotherapeutic evaluation consisted of anamnesis and postural biophotogrammetry (SAPo v 0.68^®). The comparison between the data of the SG and CG was accomplished by Student's t-test.

Results

The biophotogrammetric analysis demonstrated that the SG showed more forward head posture confirmed by the angles A9 (p = 0.0000) and CL (p = 0.0414) and also by the cervical distance (p = 0.0079). Additionally, this group presented a larger angular measure of the lumbar lordosis (p = 0.0141) compared to the CG.

Conclusion

The results indicate that adults with mouth-breathing childhood have postural alterations, mainly in the head and lumbar column, which keeps for the whole life.     

Cardiovascular risk assessment and coronary artery calcification burden in asymptomatic patients in the initial years of hemodialysis

The specific tool for cardiovascular risk assessment in hemodialysis population has not yet been proposed, despite high prevalence of cardiovascular morbidity, and mortality in clinically asymptomatic patients. Coronary artery calcium score (CACS), as a reliable predictor of future cardiovascular events, might be a valuable approach. We sought to evaluate coronary artery calcification burden and its association with clinical and laboratory parameters in asymptomatic patients who recently initiated hemodialysis. The cross-sectional study included 60 asymptomatic patients receiving chronic hemodialysis for no longer than 48 months. CACS was assessed by cardiac computed tomography. Intima-media thickness (IMT) of both common carotid and femoral arteries were measured using ultrasonography. The mean total CACS was 160.50 (443). Patients' age correlated significantly with CACS (σ = 0.367; P = 0.004), carotid (σ = 0.375; P = 0.004) and femoral IMT (σ = 0.323; P = 0.013). Patients with CACS = 0 were significantly younger than patients with CACS >400: 52.4 ± 7.91 vs. 63.88 ± 8.37 years old, respectively (P = 0.034). In patients receiving dialysis for longer than 24 months CACS, femoral and carotid IMT were higher than in those dialyzed for less than 24 months; however, none has reached significance. There was a significant positive correlation between CACS and right (σ = 0.312; P = 0.018) and left (σ = 0.521; P < 0.001) femoral IMT, while not with carotid. CACS showed significant negative correlation with the serum iron (σ = ?0.351; P = 0.007). Calcification burden varies significantly in asymptomatic patients in early years of dialysis. It correlates with patients' age and tends to increase with dialysis vintage. Femoral IMT might be useful for cardiovascular risk stratification in asymptomatic patients who recently initiated hemodialysis.     

Is ABO blood type associated with ovarian stimulation response in patients with diminished ovarian reserve?

Purpose

Recent studies have explored the relationship between ABO blood type and serum markers of ovarian reserve, specifically follicle-stimulating hormone (FSH) and anti-mullerian hormone (AMH). The primary objective of this study is to investigate whether there is an association between ABO blood type and ovarian stimulation response in patients with serum markers of diminished ovarian reserve (DOR).

Methods

This is a retrospective study of all patients undergoing controlled ovarian stimulation (COS) for in vitro fertilization (IVF) between May 2010 and July 2013. Patients were sub-grouped, a priori, based on serum AMH levels: ≤1 ng/mL, ≤0.5 ng/mL and ≤0.16 ng/mL. Within each sub-group, demographic, baseline IVF characteristics and COS response parameters based on ABO blood types were compared. The number of mature oocytes retrieved was considered the primary outcome. Analysis of variance (ANOVA) and Chi-square tests were used to compare means and percentages between ABO blood types within groups.

Results

Complete data was available for 2575 patients. The mean (± SD) age and BMI of the study cohort was 38.9 (±3.97) years, 23.4 (±5.91) kg/m², respectively. The distribution of ABO blood types in the cohort was as follows: 36.8 % (A), 6.56 % (AB), 17.3 % (B), and 39.3 % (O). The demographics and baseline IVF characteristics were comparable among patients with blood types A, AB, B, and O within each AMH group. Within each AMH sub-group, no difference was found in the total days of COS, total gonadotropins administered, peak estradiol level, or number of mature oocytes retrieved based on blood type.

Conclusions

Our results suggest no association between ABO blood type and ovarian stimulation response in patients with DOR. The predictive value of ABO blood type in determining ovarian stimulation response in such patients is currently limited.

Electronic supplementary material

The online version of this article (doi:10.1007/s10815-015-0485-3) contains supplementary material, which is available to authorized users.     

Long-term influence of fixed lingual retainers on the development of gingival recession: A retrospective,longitudinal cohort study

Objective:To investigate the long-term influence of fixed lingual retainers on the development of mandibular gingival recession and to compare the prevalence with untreated individuals.Materials and Methods:The material consisted of 144 subjects: 96 orthodontically treated patients followed for 5 years after therapy and 48 untreated age-matched subjects. The treated patients were divided in two groups: one receiving a fixed mandibular retainer (n = 48) and one receiving no form of retention in the mandible (n = 48). The presence or absence of gingival recession and calculus accumulation were scored before treatment (T0), after debonding (T1), and 5 years after debonding (T5) for each tooth in the mandibular intercanine region using plaster models and intraoral photographs. The chi-square test, one-way ANOVA, and Cochran''s Q test were used to evaluate inter- and intragroup differences.Results:The prevalence of patients with recession increased gradually and significantly throughout the observation periods in all groups, but the intergroup differences at T5 were not significant. Significantly more calculus accumulation was observed at T5 in the retainer group compared with the group without retainers.Conclusions:Long-term presence of fixed lingual retainers does not seem to increase the development of mandibular gingival recession, but does increase calculus accumulation.     

Evaluation of genotoxic potential of avarol,avarone, and its methoxy and methylamino derivatives in prokaryotic and eukaryotic test models

In this study, mutagenic and genotoxic potential of anti-tumor compounds avarol, avarone, and its derivatives 3′-methoxyavarone, 4′-(methylamino)avarone and 3′-(methylamino)avarone was evaluated and compared to cytostatics commonly used in chemotherapy (5-fluorouracil, etoposid, and cisplatin). Mutagenic potential of selected hydroquinone and quinones was assessed in prokaryotic model by the SOS/umuC assay in Salmonella typhimurium TA1535/pSK1002. Genotoxic potential was also assessed in eukaryotic models using comet assay in human fetal lung cell line (MRC-5), human adenocarcinoma epithelial cell line (A549), and in human peripheral blood cells (HPBC). The results indicated that avarol and avarone do not exert mutagenic/genotoxic potential. Among the studied avarone derivatives, mutagenic potential was detected by SOS/umuC test for 3′-(methylamino)avarone, but only after metabolic activation. The results of comet assay indicated that 3′-methoxyavarone and 3′-(methylamino)avarone have a significant impact on the level of DNA damage in the MRC-5 cell line. Genotoxic potential was not observed in A549 cells or HPBC probably due to a different uptake rate for the compounds and lower in metabolism rate within these cells.     

The needs of patients with rare disease in Serbia. Why do we need National Strategy for rare disease?

The patients with rare diseases in Serbia face the difficulties in procurement of medications as the Health insurance fund does not cover reimbursement for some medications, they face difficulties in receiving proper diagnosis which makes their position specific and complex. In an attempt to provide more support for the patients with rare diseases, their families and caregivers the helpline for rare diseases was established in October 2015. The aim of this research was to identify, examine and systematise needs of helpline users and forms of assistance provided by the team from the free helpline. The research was designed as a cross‐sectional study and was conducted between October 2015 and December 2016. The electronic database of National Organization for rare disease in Serbia helpline users was used as a data source. The user was the person who contacted helpline (patient, relative, friend, physician, etc). The “need” refers to the reasons for addressing the helpline. Helpline users had 549 needs in total; about healthcare—236 (42.98%), social care—113 (20.58%), psychological support—56 (10.20%) and other—144 (26.22%). Services were provided by the lawyer—130 (23.70%), social worker—71 (12.93%), Psychologist—56 (10.20%) and by all employees—292 (53.19%). The most common need for legal assistance among needs on healthcare was on legal aspects of access to and reimbursement of expenses for medications (32/74%–43.24%) and procedures for reimbursement of treatment abroad (11/74%–14.86%). The problems of patients with rare diseases and their families result primarily from the lack of relevant information and knowledge, as well as the non‐recognition of rare diseases in the laws and regulations of health and social care. Some problems can simply be solved by legal changes and by a better organisation and do not require additional funding. Only by adopting and implementing the National Strategy and Action Plan for Rare Diseases, the greatest number of problems and needs of people with rare diseases can be systematised and solved.