Iodine status of teenage girls on the island of Ireland

The trace element iodine is a vital constituent of thyroid hormones. Iodine requirements increase during pregnancy, when even mild deficiency may affect th     

Immunological Correlates of Response to Immune Checkpoint Inhibitors in Metastatic Urothelial Carcinoma

Background

The identification of prognostic and/or predictive biomarkers for response to immune checkpoint inhibitors (ICI) could help guide treatment decisions.

Objective

We assessed changes in programmed cell death-1 (PD1)/PD1 ligand (PDL1) expression in key immunomodulatory cell subsets (myeloid-derived suppressor cells [MDSC]; cytotoxic T lymphocytes [CTL]) following ICI therapy and investigated whether these changes correlated with outcomes in patients with metastatic urothelial carcinoma (mUC).

Patients and Methods

Serial peripheral blood samples were collected from ICI-treated mUC patients. Flow cytometry was used to quantify PD1/PDL1 expression on MDSC (CD33⁺HLADR^?) and CTL (CD8⁺CD4^?) from peripheral blood mononuclear cells. MDSC were grouped into monocytic (M)-MDSC (CD14⁺CD15^?), polymorphonuclear (PMN)-MDSC (CD14^?CD15⁺), and immature (I)-MDSC (CD14^?CD15^?). Mixed-model regression and Wilcoxon signed-rank or rank-sum tests were performed to assess post-ICI changes in immune biomarker expression and identify correlations between PD1/PDL1 expression and objective response to ICI.

Results

Of 41 ICI-treated patients, 26 received anti-PDL1 (23 atezolizumab/3 avelumab) and 15 received anti-PD1 (pembrolizumab) therapy. Based on available data, 27.5% had prior intravesical Bacillus Calmette–Guérin therapy, 42% had prior neoadjuvant chemotherapy, and 70% had prior cystectomy or nephroureterectomy. Successive doses of anti-PDL1 correlated with decreased percentage of PDL1⁺ (%PDL1⁺) M-MDSC, while doses of anti-PD1 correlated with decreased %PD1⁺ M- and I-MDSC. Although pre-treatment %PD1⁺ CTL did not predict response, a greater %PD1⁺ CTL within 9 weeks after ICI initiation correlated with objective response.

Conclusions

Treatment with ICI correlated with distinct changes in PD1/PDL1-expressing peripheral immune cell subsets, which may predict objective response to ICI. Further studies are required to validate immune molecular expression as a prognostic and/or predictive biomarker for long-term outcomes in mUC.

     

Micellar TIA1 with folded RNA binding domains as a model for reversible stress granule formation

TIA1, a protein critical for eukaryotic stress response and stress granule formation, is structurally characterized in full-length form. TIA1 contains three RNA recognition motifs (RRMs) and a C-terminal low-complexity domain, sometimes referred to as a “prion-related domain” or associated with amyloid formation. Under mild conditions, full-length (fl) mouse TIA1 spontaneously oligomerizes to form a metastable colloid-like suspension. RRM2 and RRM3, known to be critical for function, are folded similarly in excised domains and this oligomeric form of apo fl TIA1, based on NMR chemical shifts. By contrast, the termini were not detected by NMR and are unlikely to be amyloid-like. We were able to assign the NMR shifts with the aid of previously assigned solution-state shifts for the RRM2,3 isolated domains and homology modeling. We present a micellar model of fl TIA1 wherein RRM2 and RRM3 are colocalized, ordered, hydrated, and available for nucleotide binding. At the same time, the termini are disordered and phase separated, reminiscent of stress granule substructure or nanoscale liquid droplets.

T cell intracellular antigen-1 (TIA1) has multiple roles within cells, including a critical role in stress granule (SG) formation during eukaryotic cellular stress response (1–3) and translation regulation (4–6). SGs appear in cells exposed to stressors, such as pH, oxidation, and temperature changes, and contain stalled preinitiation RNA–protein complexes. They have been hypothesized to act as a decision point in mRNA processing by helping to guide homeostasis-restoring protein expression or begin apoptosis. Although sometimes associated with misfolded protein aggregates, SG components dissolve and regain function more quickly than other aggregates after the stress is removed (7). TIA1 has three RNA recognition motifs (RRM1, RRM2, RRM3) known to bind RNA with relatively little sequence specificity. TIA1 has a C-terminal low-complexity domain (LCD) enriched with asparagine and glutamine that has been referred to in the literature as a prion-related domain (PRD) because of its sequence similarity to amyloid- or prion-forming proteins. Proteins associated with SGs have also been linked to several human diseases, some characterized as protein misfolding disorders. A mutation within the LCD of TIA1 is the diagnostic marker for Welander distal myopathy (8, 9), and several other TIA1 mutations are linked to amyotrophic lateral sclerosis (10).Despite its importance, little is known about the full-length (fl) or oligomeric form(s) of TIA1 or about the LCD. The RRM domains have been structurally characterized (11–13), giving insight into structure, dynamics, binding, and function. Several excised TIA1-RRM domain constructs were characterized with small-angle scattering and liquid-state NMR; the LCD was excluded from the constructs used in prior published structural studies (11, 13). NMR was used to solve the structure of TIA1-RRM1 (Protein Data Bank [PDB] ID code 5O2V), TIA1-RRM2 bound to the dinucleotide UU-RNA (PDB ID code 5O3J), and TIA1-RRM2,3 (PDB ID code 2MJN). RRM1 appears to contribute little to RNA binding, which may be explained by the negatively charged residues in the RNP1 motif within RRM1. A model of rigid RRM domains with flexible linkers was used to interpret scattering data and show that RRM2 and RRM3 associate more closely with each other and more so after RNA binding than with RRM1. However, the effects of the LCD on the fl structure have remained elusive due to experimental challenges.It has been reported that the LCD of TIA1 can cause phase separation (14). In vivo, phase separation of groups of functionally related, locally concentrated proteins and nucleic acids (14) is believed to lead to the formation of membraneless organelles (biomolecular condensates), such as stress granules (15). Many cellular condensates contain proteins with RNA-binding domains, including Cajal bodies, P bodies, and SGs (15). Misregulation of phase separation has been implicated in several human disease-related functions (8, 9).Many proteins with LCDs also spontaneously partition into separate phases or form gels at high concentrations in vitro, potentially providing a model for in vivo phase separation. The in vitro systems share important properties with the corresponding in vivo systems. Both can undergo transitions and display a continuum of mechanical properties from liquid-like droplets to glassy (16), solid-like particles. Liquid–liquid droplets are typically micrometer, morphologically spherical domains that exhibit liquid-like dynamics in their rapid recovery from photobleaching and solution-state NMR spectra (17). Many liquid droplets or condensates in vitro are metastable and transform over time (16, 18) in a process referred to as hardening or maturation (7, 10, 16, 19). Analogously, membraneless organelles can undergo transitions in vivo during regulated maturation processes (15, 20, 21). Thus, it has been suggested that misfolded, amyloid-like fibrils and aggregates form during maturation of the membraneless organelles (7), suggesting a role for condensates in templating the formation of disease-related fibrils (22). Furthermore, the multiphase in vitro suspensions can be compared to colloids, in that they are homogeneously distributed, stable multiphase suspensions whose formation is controlled by salt concentration, viscogens, and temperature. However useful these analogies are, it is important to note that the in vitro systems are, of course, highly simplified compared to the in vivo situation. The in vivo systems are subject to important biological control over their formation and dissolution and include many other components such as nucleic acids and other proteins.The LCD/PRD of TIA1 has primary sequence similarity to the better-characterized SUP35 prion protein and is also similar to other amyloid-forming proteins (23–25). Atomic force and electron microscopy (EM) have been used to show that TIA1 forms fibers under some conditions (26, 27). Congo red and thioflavin T binding assays have been used to suggest TIA1 forms a cross-β amyloid (26, 28). Sup35 and FUS are proteins with a domain structure and an LCD analogous to TIA1; both have been reported to form amyloids (29). Alternatively, it has been hypothesized that the LCD in multidomain proteins can be unfolded (intrinsically disordered) even in the functional form and that oligomerization might be driven by nonspecific intermolecular interactions between several LCDs on different monomers (7, 30, 31). A dominant hypothesis in the literature has been that the LCD induces disease-related amyloid formation. Many proposed functions of TIA1, such as RNA sequestration into SGs (16), raise the question of whether the RRM domains are folded in the condensates or high-order oligomeric forms.Here we report structural studies of fl apo TIA1 prepared without the use of harsh solvents or denaturants. High-order oligomeric systems such as amyloid fibrils are often challenging systems for traditional structural biology methods. However, solid-state NMR (SSNMR) and EM have been powerful tools for studying these systems. We characterize fl TIA1 with EM and SSNMR to test for the presence of a solid-like phase (fibril), a liquid-like phase (intrinsically disordered protein), or some other structure. We address which domains are folded or ordered, which are solvent exposed, and whether the oligomeric structure is compatible with binding at the RRMs. The answers to these intensely debated questions have consequences for future studies of biomolecular condensates.     

LDIflare small fiber function in normal glucose tolerant subjects with and without hypertriglyceridemia

Introduction: We explored determinants of small fiber function (SFF) in normoglycemic individuals to determine influence of metabolic parameters, including triglyceride (TG) levels. Methods: Dorsal foot SFF was assessed by the LDIflare method in 79 individuals without clinical neuropathy, including 43 controls (HC, <1.7 mmol/L), 17 with mild hypertriglyceridemia (MiTG, 1.7–2.25), and 19 with significant hypertriglyceridemia (HiTG, >2.25 mmol/L). Results: LDIflare was significantly smaller in HiTG compared with HC (4.4 ± 1.4 vs. 9.3 ± 2.9 cm²; P < 0.0001) and compared with the MiTG (4.4 ± 1.4 vs. 7.0 ± 2.1; P < 0.0001). Over all, an inverse correlation existed between LDIflare and age (?0.42; P < 0.0001), weight (r = ?0.37; P = 0.004), body mass index (BMI) (?0.51; P < 0.0001), Log₁₀ triglycerides (r = ?0.66; P < 0.0001), total cholesterol (r = ?0.26; P = 0.02), and TC/HDL ratio (r = ?0.40; P = 0.002). In multivariate regression analysis, Log₁₀ triglycerides (P < 0.0001) and age (P = 0.003) were the only independent predictors. Conclusions: There is an inverse correlation between small fiber function and triglycerides in normoglycemic individuals and abnormal SFF in normoglycemic hypertriglyceridemia. Larger prospective studies are required to confirm these findings and to determine whether reduced SFF heralds later clinical neuropathy. Muscle Nerve 52 : 113–119, 2015     

Randomised, double blind, placebo-controlled trial of selenium supplementation in adult asthma

BACKGROUND: Epidemiological evidence from observational studies has suggested that blood levels and dietary intake of selenium of adults with asthma are lower than those of controls. The only previous trial of selenium supplementation in adults with asthma found no objective evidence of benefit but involved only 24 participants. METHODS: A randomised, double blind, placebo-controlled trial of selenium supplementation was performed in adults with asthma in London, UK, the majority of whom (75%) reported inhaled steroid use at baseline. 197 participants were randomised to receive either a high-selenium yeast preparation (100 microg daily, n=99) or placebo (yeast only, n=98) for 24 weeks. The primary outcome was asthma-related quality of life (QoL) score. Secondary outcomes included lung function, asthma symptom scores, peak flow and bronchodilator usage. Linear regression was used to analyse the change in outcome between the two treatment arms by "intention to treat". RESULTS: There was a 48% increase in plasma selenium between baseline and end of trial in the active treatment group but no change in the placebo group. While the QoL score improved more in the active treatment group than in the placebo group, the difference in change in score between the two groups was not significant (-0.05 (95% CI -0.19 to 0.09); p=0.47). Selenium supplementation was not associated with any significant improvement in secondary outcomes compared with placebo. CONCLUSIONS: Selenium supplementation had no clinical benefit in adults with asthma, the majority of whom were taking inhaled steroids.