A Novel Macrophage Subpopulation Conveys Increased Genetic Risk of Coronary Artery Disease.

BACKGROUND: Coronary artery disease (CAD), the leading cause of death worldwide, is influenced by both environmental and genetic factors. Although over 250 genetic risk loci have been identified through genome-wide association studies, the specific causal variants and their regulatory mechanisms are still largely unknown, particularly in disease-relevant cell types like macrophages. METHODS: We utilized single-cell RNA-seq and single-cell multiomics approaches in primary human monocyte-derived macrophages to explore the transcriptional regulatory network involved in a critical pathogenic event of coronary atherosclerosis-the formation of lipid-laden foam cells. The relative genetic contribution to CAD was assessed by partitioning disease heritability across different macrophage subpopulations. Meta-analysis of single-cell RNA-seq data sets from 38 human atherosclerotic samples was conducted to provide high-resolution cross-referencing to macrophage subpopulations in vivo. RESULTS: We identified 18 782 cis-regulatory elements by jointly profiling the gene expression and chromatin accessibility of >5000 macrophages. Integration with CAD genome-wide association study data prioritized 121 CAD-related genetic variants and 56 candidate causal genes. We showed that CAD heritability was not uniformly distributed and was particularly enriched in the gene programs of a novel CD52-hi lipid-handling macrophage subpopulation. These CD52-hi macrophages displayed significantly less lipoprotein accumulation and were also found in human atherosclerotic plaques. We investigated the cis-regulatory effect of a risk variant rs10488763 on FDX1, implicating the recruitment of AP-1 and C/EBP-ß in the causal mechanisms at this locus. CONCLUSIONS: Our results provide genetic evidence of the divergent roles of macrophage subsets in atherogenesis and highlight lipid-handling macrophages as a key subpopulation through which genetic variants operate to influence disease. These findings provide an unbiased framework for functional fine-mapping of genome-wide association study results using single-cell multiomics and offer new insights into the genotype-environment interactions underlying atherosclerotic disease.

DNA methylases for site-selective inhibition of type IIS restriction enzyme activity.

DNA methylases of the restriction-modifications (R-M) systems are promising enzymes for the development of novel molecular and synthetic biology tools. Their use in vitro enables the deployment of independent and controlled catalytic reactions. This work aimed to produce recombinant DNA methylases belonging to the R-M systems, capable of in vitro inhibition of the type IIS restriction enzymes BsaI, BpiI, or LguI. Non-switchable methylases are those whose recognition sequences fully overlap the recognition sequences of their associated endonuclease. In switch methylases, the methylase and endonuclease recognition sequences only partially overlap, allowing sequence engineering to alter methylation without altering restriction. In this work, ten methylases from type I and II R-M systems were selected for cloning and expression in E. coli strains tolerant to methylation. Isopropyl ß-D-1-thiogalactopyranoside (IPTG) concentrations and post-induction temperatures were tested to optimize the soluble methylases expression, which was achieved with 0.5 mM IPTG at 20 °C. The C-terminal His6-Tag versions showed better expression than the N-terminal tagged versions. DNA methylation was analyzed using purified methylases and custom test plasmids which, after the methylation reactions, were digested using the corresponding associated type IIS endonuclease. The non-switchable methylases M2.Eco31I, M2.BsaI, M2.HpyAII, and M1.MboII along with the switch methylases M.Osp807II and M2.NmeMC58II showed the best activity for site-selective inhibition of type IIS restriction enzyme activity. This work demonstrates that our recombinant methylases were able to block the activity of type IIS endonucleases in vitro, allowing them to be developed as valuable tools in synthetic biology and DNA assembly techniques. KEY POINTS: • Non-switchable methylases always inhibit the relevant type IIS endonuclease activity • Switch methylases inhibit the relevant type IIS endonuclease activity depending on the sequence engineering of their recognition site • Recombinant non-switchable and switch methylases were active in vitro and can be deployed as tools in synthetic biology and DNA assembly.

Quality of life in older adults with chronic kidney disease and transient changes in renal function: Findings from the Oxford Renal cohort.

BACKGROUND: Quality of life (QoL) is an important measure of disease burden and general health perception. The relationship between early chronic kidney disease (CKD) and QoL remains poorly understood. The Oxford Renal Study (OxRen) cohort comprises 1063 adults aged ≥60 years from UK primary care practices screened for early CKD, grouped according to existing or screen-detected CKD diagnoses, or biochemistry results indicative of reduced renal function (referred to as transient estimated glomerular filtration rate (eGFR) reduction). OBJECTIVES: This study aimed to compare QoL in participants known to have CKD at recruitment to those identified as having CKD through a screening programme. METHODS: Health profile data and multi-attribute utility scores were reported for two generic questionnaires: 5-level EuroQol-5 Dimension (EQ-5D-5L) and ICEpop CAPability measure for Adults (ICECAP-A). QoL was compared between patients with existing and screen-detected CKD; those with transient eGFR reduction served as the reference group in univariable and multivariable linear regression. RESULTS: Mean and standard deviation utility scores were not significantly different between the subgroups for EQ-5D-5L (screen-detected:0.785±0.156, n = 480, transient:0.779±0.157, n = 261, existing CKD:0.763±0.171, n = 322, p = 0.216) or ICECAP-A (screen-detected:0.909±0.094, transient:0.904±0.110, existing CKD:0.894±0.115, p = 0.200). Age, smoking status, and number of comorbidities were identified as independent predictors of QoL in this cohort. CONCLUSION: QoL of participants with existing CKD diagnoses was not significantly different from those with screen-detected CKD or transient eGFR reduction and was similar to UK mean scores for the same age, suggesting that patient burden of early CKD is minor. Moreover, CKD-related comorbidities contribute more significantly to disease burden in earlier stages of CKD than renal function per se. Larger prospective studies are required to define the relationship between QoL and CKD progression more precisely. These data also confirm the essentially asymptomatic nature of CKD, implying that routine screening or case finding are required to diagnose it.

Change in glomerular filtration rate over time in the Oxford Renal Cohort Study: observational study.

BACKGROUND: Decline in kidney function can result in adverse health outcomes. The Oxford Renal Cohort Study has detailed baseline assessments from 884 participants ≥60 years of age. AIM: To determine the proportion of participants with a decline in estimated glomerular filtration rate (eGFR), identify determinants of decline, and determine proportions with chronic kidney disease (CKD) remission. DESIGN AND SETTING: Observational cohort study in UK primary care. METHOD: Data were used from baseline and annual follow-up assessments to monitor change in kidney function. Rapid eGFR decline was defined as eGFR decrease >5 ml/min/1.73 m2/year, improvement as eGFR increase >5 ml/min/1.73 m2/year, and remission in those with CKD at baseline and eGFR >60 ml/min/1.73 m2 during follow-up. Cox proportional hazard models were used to identify factors associated with eGFR decline. RESULTS: There was a net decline in eGFR in the 884 participants over 5 years of follow-up. In 686 participants with >2 eGFR tests with a median follow-up of 2.1 years, 164 (24%) evidenced rapid GFR decline, 185 (27%) experienced eGFR improvement, and 82 of 394 (21%) meeting CKD stage 1-4 at baseline experienced remission. In the multivariable analysis, smoking status, higher systolic blood pressure, and being known to have CKD at cohort entry were associated with rapid GFR decline. Those with CKD stage 3 at baseline were less likely to exhibit GFR decline compared with normal kidney function. CONCLUSION: This study established that 24% of people evidenced rapid GFR decline whereas 21% evidenced remission of CKD. People at risk of rapid GFR decline may benefit from closer monitoring and appropriate treatment to minimise risks of adverse outcomes, although only a small proportion meet the National Institute for Health and Care Excellence criteria for referral to secondary care.

Extracellular succinate hyperpolarizes M2 macrophages through SUCNR1/GPR91-mediated Gq signaling.

Succinate functions both as a classical TCA cycle metabolite and an extracellular metabolic stress signal sensed by the mainly Gi-coupled succinate receptor SUCNR1. In the present study, we characterize and compare effects and signaling pathways activated by succinate and both classes of non-metabolite SUCNR1 agonists. By use of specific receptor and pathway inhibitors, rescue in G-protein-depleted cells and monitoring of receptor G protein activation by BRET, we identify Gq rather than Gi signaling to be responsible for SUCNR1-mediated effects on basic transcriptional regulation. Importantly, in primary human M2 macrophages, in which SUCNR1 is highly expressed, we demonstrate that physiological concentrations of extracellular succinate act through SUCNR1-activated Gq signaling to efficiently regulate transcription of immune function genes in a manner that hyperpolarizes their M2 versus M1 phenotype. Thus, sensing of stress-induced extracellular succinate by SUCNR1 is an important transcriptional regulator in human M2 macrophages through Gq signaling.

Frequency of Renal Monitoring - Creatinine and Cystatin C (FORM-2C): an observational cohort study of patients with reduced eGFR in primary care.

BACKGROUND: Monitoring is the mainstay of chronic kidney disease management in primary care; however, there is little evidence about the best way to do this. AIM: To compare the effectiveness of estimated glomerular filtration rate (eGFR) derived from serum creatinine and serum cystatin C to predict renal function decline among those with a recent eGFR of 30-89 ml/min/1.73 m2. DESIGN AND SETTING: Observational cohort study in UK primary care. METHOD: Serum creatinine and serum cystatin C were both measured at seven study visits over 2 years in 750 patients aged ≥18 years with an eGFR of 30-89 ml/min/1.73 m2 within the previous year. The primary outcome was change in eGFR derived from serum creatinine or serum cystatin C between 6 and 24 months. RESULTS: Average change in eGFR was 0.51 ml/min/1.73 m2/year when estimated by serum creatinine and -2.35 ml/min/1.73 m2/year when estimated by serum cystatin C. The c-statistic for predicting renal decline using serum creatininederived eGFR was 0.495 (95% confidence interval [CI] = 0.471 to 0.519). The equivalent c-statistic using serum cystatin C-derived eGFR was 0.497 (95% CI = 0.468 to 0.525). Similar results were obtained when restricting analyses to those aged ≥75 or <75 years, or with eGFR ≥60 ml/min/1.73 m2. In those with eGFR <60 ml/min/1.73 m2, serum cystatin C-derived eGFR was more predictive than serum creatinine-derived eGFR for future decline in kidney function. CONCLUSION: In the primary analysis neither eGFR estimated from serum creatinine nor from serum cystatin C predicted future change in kidney function, partly due to small changes during 2 years. In some secondary analyses there was a suggestion that serum cystatin C was a more useful biomarker to estimate eGFR, especially in those with a baseline eGFR <60 ml/min/1.73 m2.

Prevalence and factors associated with multimorbidity among primary care patients with decreased renal function.

OBJECTIVES: To establish the prevalence of multimorbidity in people with chronic kidney disease (CKD) stages 1-5 and transiently impaired renal function and identify factors associated with multimorbidity. DESIGN AND SETTING: Prospective cohort study in UK primary care. PARTICIPANTS: 861 participants aged 60 and older with decreased renal function of whom, 584 (65.8%) had CKD and 277 (32.2%) did not have CKD. INTERVENTIONS: Participants underwent medical history and clinical assessment, and blood and urine sampling. PRIMARY AND SECONDARY OUTCOME MEASURES: Multimorbidity was defined as presence of ≥2 chronic conditions including CKD. Prevalence of each condition, co-existing conditions and multimorbidity were described and logistic regression was used to identify predictors of multimorbidity. RESULTS: The mean (±SD) age of participants was 74±7 years, 54% were women and 98% were white. After CKD, the next most prevalent condition was hypertension (n = 511, 59.3%), followed by obesity (n = 265, 30.8%) ischemic heart disease (n = 145, 16.8%) and diabetes (n = 133, 15.4%). Having two co-existing conditions was most common (27%), the most common combination of which was hypertension and obesity (29%). One or three conditions was the next most prevalent combination (20% and 21% respectively). The prevalence of multimorbidity was 73.9% (95%CI 70.9-76.8) in all participants and 86.6% (95%CI 83.9-89.3) in those with any-stage CKD. Logistic regression found a significant association between increasing age (OR 1.07, 95%CI 1.04-0.10), increasing BMI (OR 1.15, 95%CI 1.10-1.20) and decreasing eGFR (OR 0.99, 95%CI 0.98-1.00) with multimorbidity. CONCLUSIONS: This analysis is the first to provide an accurate estimate of the prevalence of multimorbidity in a screened older primary care population living with or at risk of CKD across all stages. Hypertension and obesity were the most common combination of conditions other than CKD that people were living with, suggesting that there may be multiple reasons for closely monitoring health status in individuals with CKD.

Prevalence of chronic kidney disease in the community using data from OxRen: a UK population-based cohort study.

BACKGROUND: Chronic kidney disease (CKD) is a largely asymptomatic condition of diminished renal function, which may not be detected until advanced stages without screening. AIM: To establish undiagnosed and overall CKD prevalence using a cross-sectional analysis. DESIGN AND SETTING: Longitudinal cohort study in UK primary care. METHOD: Participants aged ≥60 years were invited to attend CKD screening visits to determine whether they had reduced renal function (estimated glomerular filtration rate [eGFR] <60 ml/min/1.73 m2 or albumin:creatinine ratio ≥3 mg/mmol). Those with existing CKD, low eGFR, evidence of albuminuria, or two positive screening tests attended a baseline assessment (CKD cohort). RESULTS: A total of 3207 participants were recruited and 861 attended the baseline assessment. The CKD cohort consisted of 327 people with existing CKD, 257 people with CKD diagnosed through screening (CKD prevalence of 18.2%, 95% confidence interval [CI] = 16.9 to 19.6), and 277 with borderline/transient decreased renal function. In the CKD cohort, 54.4% were female, mean standard deviation (SD) age was 74.0 (SD 6.9) years, and mean eGFR was 58.0 (SD 18.4) ml/min/1.73 m2. Of the 584 with confirmed CKD, 44.0% were diagnosed through screening. Over half of the CKD cohort (51.9%, 447/861) fell into CKD stages 3-5 at their baseline assessment, giving an overall prevalence of CKD stages 3-5 of 13.9% (95% CI = 12.8 to 15.1). More people had reduced eGFR using the Modification of Diet in Renal Disease (MDRD) equation than with CKD Epidemiology Collaboration (CKD-EPI) equation in the 60-75-year age group and more had reduced eGFR using CKD-EPI in the ≥80-year age group. CONCLUSION: This study found that around 44.0% of people living with CKD are undiagnosed without screening, and prevalence of CKD stages 1-5 was 18.2% in participants aged >60 years. Follow-up will provide data on annual incidence, rate of CKD progression, determinants of rapid progression, and predictors of cardiovascular events.

A genetics-led approach defines the drug target landscape of 30 immune-related traits.

Most candidate drugs currently fail later-stage clinical trials, largely due to poor prediction of efficacy on early target selection1. Drug targets with genetic support are more likely to be therapeutically valid2,3, but the translational use of genome-scale data such as from genome-wide association studies for drug target discovery in complex diseases remains challenging4-6. Here, we show that integration of functional genomic and immune-related annotations, together with knowledge of network connectivity, maximizes the informativeness of genetics for target validation, defining the target prioritization landscape for 30 immune traits at the gene and pathway level. We demonstrate how our genetics-led drug target prioritization approach (the priority index) successfully identifies current therapeutics, predicts activity in high-throughput cellular screens (including L1000, CRISPR, mutagenesis and patient-derived cell assays), enables prioritization of under-explored targets and allows for determination of target-level trait relationships. The priority index is an open-access, scalable system accelerating early-stage drug target selection for immune-mediated disease.

Statistical models for the deterioration of kidney function in a primary care population: A retrospective database analysis.

Background: Evidence for kidney function monitoring intervals in primary care is weak, and based mainly on expert opinion. In the absence of trials of monitoring strategies, an approach combining a model for the natural history of kidney function over time combined with a cost-effectiveness analysis offers the most feasible approach for comparing the effects of monitoring under a variety of policies. This study aimed to create a model for kidney disease progression using routinely collected measures of kidney function. Methods: This is an open cohort study of patients aged ≥18 years, registered at 643 UK general practices contributing to the Clinical Practice Research Datalink between 1 April 2005 and 31 March 2014. At study entry, no patients were kidney transplant donors or recipients, pregnant or on dialysis. Hidden Markov models for estimated glomerular filtration rate (eGFR) stage progression were fitted to four patient cohorts defined by baseline albuminuria stage; adjusted for sex, history of heart failure, cancer, hypertension and diabetes, annually updated for age. Results: Of 1,973,068 patients, 1,921,949 had no recorded urine albumin at baseline, 37,947 had normoalbuminuria (<3mg/mmol), 10,248 had microalbuminuria (3-30mg/mmol), and 2,924 had macroalbuminuria (>30mg/mmol). Estimated annual transition probabilities were 0.75-1.3%, 1.5-2.5%, 3.4-5.4% and 3.1-11.9% for each cohort, respectively. Misclassification of eGFR stage was estimated to occur in 12.1% (95%CI: 11.9-12.2%) to 14.7% (95%CI: 14.1-15.3%) of tests. Male gender, cancer, heart failure and age were independently associated with declining renal function, whereas the impact of raised blood pressure and glucose on renal function was entirely predicted by albuminuria. Conclusions: True kidney function deteriorates slowly over time, declining more sharply with elevated urine albumin, increasing age, heart failure, cancer and male gender. Consecutive eGFR measurements should be interpreted with caution as observed improvement or deterioration may be due to misclassification.

Author Correction: Pathogen-derived HLA-E bound epitopes reveal broad primary anchor pocket tolerability and conformationally malleable peptide binding.

The original version of this Article contained an error in the spelling of the author Jonah B Sacha, which was incorrectly given as Jonah Sacha. These errors have now been corrected in both the PDF and HTML versions of the Article.

Pathogen-derived HLA-E bound epitopes reveal broad primary anchor pocket tolerability and conformationally malleable peptide binding.

Through major histocompatibility complex class Ia leader sequence-derived (VL9) peptide binding and CD94/NKG2 receptor engagement, human leucocyte antigen E (HLA-E) reports cellular health to NK cells. Previous studies demonstrated a strong bias for VL9 binding by HLA-E, a preference subsequently supported by structural analyses. However, Mycobacteria tuberculosis (Mtb) infection and Rhesus cytomegalovirus-vectored SIV vaccinations revealed contexts where HLA-E and the rhesus homologue, Mamu-E, presented diverse pathogen-derived peptides to CD8+ T cells, respectively. Here we present crystal structures of HLA-E in complex with HIV and Mtb-derived peptides. We show that despite the presence of preferred primary anchor residues, HLA-E-bound peptides can adopt alternative conformations within the peptide binding groove. Furthermore, combined structural and mutagenesis analyses illustrate a greater tolerance for hydrophobic and polar residues in the primary pockets than previously appreciated. Finally, biochemical studies reveal HLA-E peptide binding and exchange characteristics with potential relevance to its alternative antigen presenting function in vivo.

Mouse podoplanin supports adhesion and aggregation of platelets under arterial shear: A novel mechanism of haemostasis.

The podoplanin-CLEC-2 axis is critical in mice for prevention of hemorrhage in the cerebral vasculature during mid-gestation. This raises the question as to how platelets are captured by podoplanin on neuroepithelial cells in a high shear environment. In this study, we demonstrate that mouse platelets form stable aggregates on mouse podoplanin at arterial shear through a CLEC-2 and Src kinase-dependent pathway. Adhesion and aggregation are also dependent on the platelet glycoprotein (GP) receptors, integrin αIIbß3 and GPIb, and the feedback agonists ADP and thromboxane A2 (TxA2). CLEC-2 does not bind to von Willebrand factor (VWF) suggesting that the interaction with podoplanin is sufficient to both tether and activate platelets. Consistent with this, the surface plasmon resonance measurements reveal that mouse CLEC-2 binds to mouse podoplanin with nanomolar affinity. The present findings demonstrate a novel pathway of hemostasis in which podoplanin supports platelet capture and activation at arteriolar rates of shear.

Systematic Review and Metaanalysis Comparing the Bias and Accuracy of the Modification of Diet in Renal Disease and Chronic Kidney Disease Epidemiology Collaboration Equations in Community-Based Populations.

BACKGROUND: The majority of patients with chronic kidney disease are diagnosed and monitored in primary care. Glomerular filtration rate (GFR) is a key marker of renal function, but direct measurement is invasive; in routine practice, equations are used for estimated GFR (eGFR) from serum creatinine. We systematically assessed bias and accuracy of commonly used eGFR equations in populations relevant to primary care. CONTENT: MEDLINE, EMBASE, and the Cochrane Library were searched for studies comparing measured GFR (mGFR) with eGFR in adult populations comparable to primary care and reporting both the Modification of Diet in Renal Disease (MDRD) and the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations based on standardized creatinine measurements. We pooled data on mean bias (difference between eGFR and mGFR) and on mean accuracy (proportion of eGFR within 30% of mGFR) using a random-effects inverse-variance weighted metaanalysis. We included 48 studies of 26875 patients that reported data on bias and/or accuracy. Metaanalysis of within-study comparisons in which both formulae were tested on the same patient cohorts using isotope dilution-mass spectrometry-traceable creatinine showed a lower mean bias in eGFR using CKD-EPI of 2.2 mL/min/1.73 m2 (95% CI, 1.1-3.2; 30 studies; I2 = 74.4%) and a higher mean accuracy of CKD-EPI of 2.7% (1.6-3.8; 47 studies; I2 = 55.5%). Metaregression showed that in both equations bias and accuracy favored the CKD-EPI equation at higher mGFR values. SUMMARY: Both equations underestimated mGFR, but CKD-EPI gave more accurate estimates of GFR.

Activation of glycoprotein VI (GPVI) and C-type lectin-like receptor-2 (CLEC-2) underlies platelet activation by diesel exhaust particles and other charged/hydrophobic ligands.

Platelets are activated by a range of stimuli that share little or no resemblance in structure to each other or to recognized ligands, including diesel exhaust particles (DEP), small peptides [4N1-1, Champs (computed helical anti-membrane proteins), LSARLAF (Leu-Ser-Ala-Arg-Leu-Ala-Phe)], proteins (histones) and large polysaccharides (fucoidan, dextran sulfate). This miscellaneous group stimulate aggregation of human and mouse platelets through the glycoprotein VI (GPVI)-FcR γ-chain complex and/or C-type lectin-like receptor-2 (CLEC-2) as shown using platelets from mice deficient in either or both of these receptors. In addition, all of these ligands stimulate tyrosine phosphorylation in GPVI/CLEC-2-double-deficient platelets, indicating that they bind to additional surface receptors, although only in the case of dextran sulfate does this lead to activation. DEP, fucoidan and dextran sulfate, but not the other agonists, activate GPVI and CLEC-2 in transfected cell lines as shown using a sensitive reporter assay confirming a direct interaction with the two receptors. We conclude that this miscellaneous group of ligands bind to multiple proteins on the cell surface including GPVI and/or CLEC-2, inducing activation. These results have pathophysiological significance in a variety of conditions that involve exposure to activating charged/hydrophobic agents.

The Oxford Renal (OxRen) cross-sectional study of chronic kidney disease in the UK.

INTRODUCTION: Chronic kidney disease (CKD) diagnosed with objective measures of kidney damage and function has been recognised as a major public health burden. Independent of age, sex, ethnicity and comorbidity, strong associations exist between cardiovascular disease, mortality, morbidity and CKD, defined by reduced glomerular filtration rate and increased urinary albumin excretion. Detection of CKD within the population is therefore a priority for health systems. METHODS AND ANALYSIS: 15 000 patients aged 60 years or over meeting the inclusion criteria will be invited to the study. Recruitment will be stratified to represent the distribution of socioeconomic position in the UK general population. Patients will be excluded if terminally ill (expected survival <1 year), or if they have received a solid organ transplant. Patients will attend up to two screening visits, to determine if they have CKD, followed by an assessment visit where demographic and physiological parameters will be recorded alongside questionnaires on exercise, diet, cognitive assessment and quality of life. Blood and urine specimens will be taken for immediate routine assays as well as for freezing pending peptide and genetic studies. Patients will have office and home blood pressure measurements as well as pulse wave velocity assessment. Healthcare costs of screening and subsequent monitoring will be calculated. ETHICS AND DISSEMINATION: The protocol and related documents have been approved by NRES Committee South Central-Oxford B-Reference 13/SC/0020.

Recognition and blocking of innate immunity cells by Candida albicans chitin.

Chitin is a skeletal cell wall polysaccharide of the inner cell wall of fungal pathogens. As yet, little about its role during fungus-host immune cell interactions is known. We show here that ultrapurified chitin from Candida albicans cell walls did not stimulate cytokine production directly but blocked the recognition of C. albicans by human peripheral blood mononuclear cells (PBMCs) and murine macrophages, leading to significant reductions in cytokine production. Chitin did not affect the induction of cytokines stimulated by bacterial cells or lipopolysaccharide (LPS), indicating that blocking was not due to steric masking of specific receptors. Toll-like receptor 2 (TLR2), TLR4, and Mincle (the macrophage-inducible C-type lectin) were not required for interactions with chitin. Dectin-1 was required for immune blocking but did not bind chitin directly. Cytokine stimulation was significantly reduced upon stimulation of PBMCs with heat-killed chitin-deficient C. albicans cells but not with live cells. Therefore, chitin is normally not exposed to cells of the innate immune system but is capable of influencing immune recognition by blocking dectin-1-mediated engagement with fungal cell walls.

Single nucleotide polymorphism analysis of the NKG2D ligand cluster on the long arm of chromosome 6: Extensive polymorphisms and evidence of diversity between human populations.

NKG2D is an important activating receptor on NK cells and T-cells and has a diverse panel of ligands (NKG2DL) which include the ULBP and RAET1 proteins. Several NKG2DL exhibit a considerable degree of genetic polymorphism, and although the functional significance of such allelic variation remains unclear, genetic variants have been implicated in susceptibility to infection and auto-immune disease. We used sequence-specific primer polymerase chain reaction to determine the frequency of 25 single nucleotide polymorphisms (SNPs) in the promoter and coding regions of genes of the RAET1/ULBP cluster in 223 Euro-Caucasoid, 60 Afro-Caribbean, and 52 Indo-Asian individuals to determine NKG2DL allele and haplotype frequencies within these populations. We show marked differences in the frequency of NKG2DL SNPs and haplotypes among the three ethnic groups, and certain haplotypes were observed almost exclusively in Afro-Caribbean compared with the Euro-Caucasoid and Indo-Asian populations. Interestingly, variation was focused within the RAET1E (ULBP4), RAET1L, and ULBP3 genes, whereas the ULBP1, ULBP2 and RAET1G (ULBP5) genes were highly conserved. These findings suggest that individual NKG2DL alleles have been subject to divergent selective pressures during the migration of Homo sapiens. This information will be of importance in understanding the biology and clinical significance of NKG2DL polymorphism.

Reversible renal impairment caused by thyroid disease.

Renal impairment is a common finding in clinical practice and is increasingly recognized with the routine reporting of estimated glomerular filtration rates. Clinical assessment is essential to determine which of the many possible investigations are appropriate. Thyroid hormones regulate many cellular functions, and abnormalities of the active thyroid hormones, thyroxine (T(4)) and tri-iodothyronine (T(3)), can influence serum creatinine levels. Evaluation of thyroid function is easily overlooked, but important in this context, as hypothyroidism is common and can cause renal impairment, which is typically reversible. Renal dysfunction may also be more frequent in hyperthyroidism than is recognized. This report describe how a dramatic elevation in serum creatinine paralleled the development of hyperthyroidism, with a return of the creatinine to normal following treatment of the hyperthyroid state.

The platelet receptor CLEC-2 is active as a dimer.

The platelet receptor CLEC-2 binds to the snake venom toxin rhodocytin and the tumor cell surface protein podoplanin. Binding of either of these ligands promotes phosphorylation of a single tyrosine residue in the YXXL motif in the intracellular domain of CLEC-2. Phosphorylation of this tyrosine initiates binding of spleen tyrosine kinase (Syk) and triggers further downstream signaling events and ultimately potent platelet activation and aggregation. However, it is unclear how a single YXXL motif can interact efficiently with Syk, which usually recognizes two tandem YXXL repeats presented as an immunoreceptor tyrosine-based activation motif (ITAM). Using bioluminescence resonance energy transfer, coimmunopreciptitation, recombinant protein expression and analytical gel filtration chromatography, surface plasmon resonance, Western blotting, multiangle light scattering (MALS), and analytical ultracentrifugation, we show that CLEC-2 exists as a non-disulfide-linked homodimer which could allow each Syk molecule to interact with two YXXL motifs, one from each CLEC-2 monomer.