Emerging role of interleukin‐33 in autoimmune diseases

Interleukin‐33 (IL‐33) is a member of the IL‐1 cytokine family. It predominantly induces type 2 immune responses and thus is protective against atherosclerosis and nematode infections but contributes to allergic airway inflammation. Interleukin‐33 also plays a pivotal role in the development of many autoimmune diseases through mechanisms that are still not fully understood. In this review, we focus on the recent advances in understanding of the expression and function of IL‐33 in some autoimmune disorders, aiming to provide insight into its potential role in disease development.     

Characterization of the antibody response to the receptor binding domain of botulinum neurotoxin serotypes A and E

Clostridium botulinum neurotoxins (BoNTs) are the most toxic proteins for humans. The current clostridial-derived vaccines against BoNT intoxication have limitations including production and accessibility. Conditions were established to express the soluble receptor binding domain (heavy-chain receptor [HCR]) of BoNT serotypes A and E in Escherichia coli. Sera isolated from mice and rabbits immunized with recombinant HCR/A1 (rHCR/A1) from the classical type A-Hall strain (ATCC 3502) (BoNT/A1) and rHCR/E from BoNT serotype E Beluga (BoNT/E(B)) neutralized the homologous serotype of BoNT but displayed differences in cross-recognition and cross-protection. Enzyme-linked immunosorbent assay and Western blotting showed that alpha-rHCR/A1 recognized epitopes within the C terminus of the HCR/A and HCR/E, while alpha-rHCR/E recognized epitopes within the N terminus or interface between the N and C termini of the HCR proteins. alpha-rHCR/E(B) sera possessed detectable neutralizing capacity for BoNT/A1, while alpha-rHCR/A1 did not neutralize BoNT/E. rHCR/A was an effective immunogen against BoNT/A1 and the Kyoto F infant strain (BoNT/A2), but not BoNT serotype E Alaska (BoNT/E(A)), while rHCR/E(B) neutralized BoNT/E(A), and under hyperimmunization conditions protected against BoNT/A1 and BoNT/A2. The protection elicited by rHCR/A1 to BoNT/A1 and BoNT/A2 and by rHCR/E(B) to BoNT/E(A) indicate that immunization with receptor binding domains elicit protection within sub-serotypes of BoNT. The protection elicited by hyperimmunization with rHCR/E against BoNT/A suggests the presence of common neutralizing epitopes between the serotypes E and A. These results show that a receptor binding domain subunit vaccine protects against serotype variants of BoNTs.     

Sequence variation within botulinum neurotoxin serotypes impacts antibody binding and neutralization

The botulinum neurotoxins (BoNTs) are category A biothreat agents which have been the focus of intensive efforts to develop vaccines and antibody-based prophylaxis and treatment. Such approaches must take into account the extensive BoNT sequence variability; the seven BoNT serotypes differ by up to 70% at the amino acid level. Here, we have analyzed 49 complete published sequences of BoNTs and show that all toxins also exhibit variability within serotypes ranging between 2.6 and 31.6%. To determine the impact of such sequence differences on immune recognition, we studied the binding and neutralization capacity of six BoNT serotype A (BoNT/A) monoclonal antibodies (MAbs) to BoNT/A1 and BoNT/A2, which differ by 10% at the amino acid level. While all six MAbs bound BoNT/A1 with high affinity, three of the six MAbs showed a marked reduction in binding affinity of 500- to more than 1,000-fold to BoNT/A2 toxin. Binding results predicted in vivo toxin neutralization; MAbs or MAb combinations that potently neutralized A1 toxin but did not bind A2 toxin had minimal neutralizing capacity for A2 toxin. This was most striking for a combination of three binding domain MAbs which together neutralized >40,000 mouse 50% lethal doses (LD(50)s) of A1 toxin but less than 500 LD(50)s of A2 toxin. Combining three MAbs which bound both A1 and A2 toxins potently neutralized both toxins. We conclude that sequence variability exists within all toxin serotypes, and this impacts monoclonal antibody binding and neutralization. Such subtype sequence variability must be accounted for when generating and evaluating diagnostic and therapeutic antibodies.     

A randomised controlled trial of extended anticoagulation treatment versus standard treatment for the prevention of recurrent venous thromboembolism (VTE) and post-thrombotic syndrome in patients being treated for a first episode of unprovoked VTE (the ExACT study)

Venous thromboembolism (VTE) is prevalent and impactful, with a risk of death, morbidity and recurrence. Post-thrombotic syndrome (PTS) is a common consequence and associated with impaired quality of life (QoL). The ExACT study was a non-blinded, prospective, multicentred randomised controlled trial comparing extended versus limited duration anticoagulation following a first unprovoked VTE (proximal deep vein thrombosis or pulmonary embolism). Adults were eligible if they had completed ≥3 months anticoagulation (remaining anticoagulated). The primary outcome was time to first recurrent VTE from randomisation. The secondary outcomes included PTS severity, bleeding, QoL and D-dimers. Two-hundred and eighty-one patients were recruited, randomised and followed up for 24 months (mean age 63, male:female 2:1). There was a significant reduction in recurrent VTE for patients receiving extended anticoagulation [2·75 vs. 13·54 events/100 patient years, adjusted hazard ratio (aHR) 0·20 (95% confidence interval (CI): 0·09 to 0·46, P < 0·001)] with a non-significant increase in major bleeding [3·54 vs. 1·18 events/100 patient years, aHR 2·99 (95% CI: 0·81–11·05, P = 0·10)]. Outcomes of PTS and QoL were no different between groups. D-dimer results (on anticoagulation) did not predict VTE recurrence. In conclusion, extended anticoagulation reduced VTE recurrence but did not reduce PTS or improve QoL and was associated with a non-significant increase in bleeding. Results also suggest very limited clinical utility of D-dimer testing on anticoagulated patients.     

Diurnal variation in plasma concentrations of testosterone, 5α-dihydrotestosterone,and corticosteroids in the Australian brush-tailed possum, Trichosurus vulpecula (Kerr)

Plasma concentrations of testosterone, 5α-dihydrotestosterone, and total adrenal corticosteroids were measured in intact and castrated males and female possums over a 24-h period. In males, testosterone levels varied diurnally, being significantly higher in the morning than in the evening, with an overall mean concentration of 3.30 ± 0.43 (SEM) ng/ml. Levels of 5α-dihydrotestosterone showed a similar variation but of lower magnitude and the overall mean plasma concentration was 0.63 ± 0.10 ng/ml. Total adrenal corticosteroid concentrations in males also appeared to cycle, but inversely to the androgens with a peak in the early evening, and the overall mean concentration was 0.61 ± 0.08 μg/100 ml. Testosterone concentrations averaged 0.46 ± 0.02 and 0.35 ± 0.01 ng/ml in castrated males and females, respectively, and the corresponding values for 5α-dihydrotestosterone were 0.20 ± 0.03 and 0.21 ± 0.03 ng/ml. These measurements indicate that plasma testosterone levels of the marsupial possum fall within the range reported for eutherian species.     

In Situ Activation of Helper T Cells in the Lung

To better understand the lung and systemic responses of helper T cells mediating memory immunity to Mycobacterium tuberculosis, we used three- and four-color flow cytometry to study the surface phenotype of CD4(+) lymphocytes. Bronchoalveolar lavage (BAL) fluid and peripheral blood (PB) samples were obtained from a total of 25 subjects, including 10 tuberculosis (TB)-infected subjects, 8 purified-protein-derivative-negative subjects, and 7 purified-protein-derivative-positive subjects. In marked contrast to CD4(+) lymphocytes from PB (9% +/- 5% expressing CD45RA and CD29), the majority (55% +/- 16%) of CD4(+) lymphocytes in BAL (ALs) simultaneously expressed CD45RA, a na?ve T-cell marker, and CD29, members of the very late activation family. Further evaluation revealed that CD4(+) ALs expressed both CD45RA and CD45RO, a memory T-cell marker. In addition, the proportion of CD4(+) lymphocytes expressing CD69, an early activation marker, was drastically increased in BAL fluid (83% +/- 9%) compared to PB (1% +/- 1%), whereas no significant difference was seen in the expression of CD25, the low-affinity interleukin 2 receptor (34% +/- 15% versus 40% +/- 16%). More importantly, we identified a minor population of CD69(bright) CD25(bright) CD4(+) lymphocytes in BAL (10% +/- 6%) that were consistently absent from PB (1% +/- 1%). Thus, CD4(+) lymphocytes in the lung paradoxically coexpress surface molecules characteristic of na?ve and memory helper T cells as well as surface molecules commonly associated with early and late stages of activation. No difference was observed for ALs obtained from TB-infected and uninfected lung segments in this regard. It remains to be determined if these surface molecules are induced by the alveolar environment or if CD4(+) lymphocytes coexpressing this unusual combination of surface molecules are selectively recruited from the circulation. Our data suggest that ex vivo experiments on helper T-cell subsets that display distinctive phenotypes may be pivotal to studies on the human immune response to potential TB vaccines.     

Two British women studies replicated the association between the Val66Met polymorphism in the brain-derived neurotrophic factor (BDNF) and BMI

The goal of this study is to investigate the relationship between the Val66Met polymorphism in the brain-derived neurotrophic factor (BDNF) and body mass index (BMI) in two sizable and well-characterized populations of British women: the British Women''s Heart and Health Study (BWHHS) (age 60–79 years) and the mothers from the Avon Longitudinal Study of Parents and Children (age 16–44 years). We genotyped the Val66Met polymorphism (rs6265) in these two populations, and conducted a linear regression analysis to test for an association between this polymorphism and BMI. Both study populations indicated an association between BMI and the Val66Met polymorphism, with individuals carrying the Met–Met genotype having a lower mean BMI than those with the Val–Met or Val–Val genotypes (in the BWHHS): mean BMI difference=−0.911 kg/m², 95% confidence interval (CI): −1.70 to −0.12, P=0.023; in the mothers from the Avon Longitudinal Study of Parents and Children (ALSPAC): mean BMI difference=−0.57 kg/m², 95%CI: −1.08 to −0.054, P=0.03). In a pooled analysis of these two studies, together with one further published study that provided data in a suitable format for inclusion in our meta-analysis, we found a pooled difference of −0.76 (95% CI: −1.16, −0.036) for adult women; I²–test for heterogeneity=51%, P=0.13. Our study indicated an association between BDNF and BMI in two general population studies of women. The exact role of BDNF in weight regulation merits further investigation.     

Simian immunodeficiency virus-induced CD4+ T cell deficits in cytokine secretion profile are dependent on monkey origin

Facets of the immune response early after human immunodeficiency virus (HIV) infection influence the course of disease. In the simian immunodeficiency virus (SIV)-rhesus monkey system, a global dysfunction of CD4(+) T cell cytokine secretion was reported to develop early after infection [McKay PF, Barouch DH, Schmitz JE, Veazey RS, Gorgone DA, Lifton MA, Williams KC, and Letvin NL: J Virol 2003;77:4695-4702]. Because differences have been found in SIV pathogenesis depending on the origin of the monkeys, we investigated the correlation between animal background, defined by country of origin (India or China), and circulating T cell cytokine secretion as well as cycling ability within the first 3 mo of SIV infection. An early loss of CD4(+) T cells that produce interferon (IFN)-gamma and interleukin (IL)-2, those that produce IFN-gamma but not tumor necrosis factor (TNF)-alpha, as well as those that do not express IFN-gamma but can express IL-2 or TNF-alpha, was observed in animals of Indian, but not of Chinese, origin after SIV infection. After infection CD4(+) T cells in Chinese macaques developed an increased proliferating pool of T cells compared with Indian animals. These data reveal host diversity in the global effects of SIV infection on functional subsets of immune cells, which can add to a better understanding of differences observed in populations from diverse ethnic origins.     

Reaction time variability in children with ADHD symptoms and/or dyslexia

Reaction time (RT) variability on a Stop Signal task was examined among children with attention deficit hyperactivity disorder (ADHD) symptoms and/or dyslexia in comparison to typically developing (TD) controls. Children's go-trial RTs were analyzed using a novel ex-Gaussian method. Children with ADHD symptoms had increased variability in the fast but not the slow portions of their RT distributions compared to those without ADHD symptoms. The RT distributions of children with dyslexia were similar to those of TD-controls. It is argued that variability in responding may be underpinned by impairments in response preparation or timing during Stop Signal tasks.