Toll-like receptors (TLRs) are crucial in innate recognition of invading micro-organisms and their subsequent clearance. Bacteria are not passive bystanders and have evolved complex evasion ...mechanisms.Staphylococcus aureussecretes a potent TLR2 antagonist, staphylococcal superantigen-like protein 3 (SSL3), which prevents receptor stimulation by pathogen-associated lipopeptides. Here, we present crystal structures of SSL3 and its complexwith TLR2. The structure reveals that formation of the specific inhibitory complex is predominantly mediated by hydrophobic contacts between SSL3 and TLR2 and does not involve interaction of TLR2–glycans with the conserved LewisXbinding site of SSL3. In the complex, SSL3 partially covers the entrance to the lipopeptide binding pocket in TLR2, reducing its size by ∼50%. We show that this is sufficient to inhibit binding of agonist Pam₂CSK₄ effectively, yet allows SSL3 to bind to an already formed TLR2–Pam₂CSK₄ complex. The binding site of SSL3 overlaps those of TLR2 dimerization partners TLR1 and TLR6 extensively. Combined, our data reveal a robust dual mechanism in which SSL3 interferes with TLR2 activation at two stages: by binding to TLR2, it blocks ligand binding and thus inhibits activation. Second, by interacting with an already formed TLR2–lipopeptide complex, it prevents TLR heterodimerization and downstream signaling.
Toll-like receptors (TLRs) are crucial for our host defense against microbial infections. TLR2 is especially important to fight bacterial infections, as it specifically recognizes bacterial ...lipoproteins of both Gram-positive and Gram-negative origin. Present on a variety of immune cells, TLR2 is critical for host protection against several bacterial infections, including those caused by
Staphylococcus aureus.
This major human pathogen causes increasing health care problems due to its increased resistance to antibiotics.
S. aureus
secretes a wide variety of proteins that inhibit innate immune responses. Recently, several staphylococcal superantigen-like proteins (SSLs) have been described to mediate immune evasive properties. Here, we describe that SSL3 specifically binds and inhibits TLR2 activation on human and murine neutrophils and monocytes. Through binding of the extracellular TLR2 domain, SSL3 inhibits IL-8 production by HEK cells expressing TLR1/2 and TLR2/6 dimers, stimulated with their specific ligands. The SSL3–TLR2 interaction is partially glycan dependent as binding of SSL3 to TLR2 is affected upon removal of sialic acid residues. Moreover, the SSL3(R308A) mutant lacking glycan-binding properties shows lower TLR2 inhibition. An SSL3 mutant, lacking the N-terminal 126 amino acids, still retains full TLR2 inhibiting activity. Of other SSLs tested, only SSL4, which shares the highest homology with SSL3, blocks TLR2 activation. SSL3 is the first-described bacterial protein that blocks TLR2 activation through direct extracellular interaction with the receptor. This unique function of SSL3 adds to the arsenal of immune evasive molecules that
S. aureus
can employ to subvert both innate and adaptive immunity.
Objectives
Rheumatoid arthritis (RA) patients show an earlier circadian rhythm (i.e. serum melatonin peaks earlier during the night, indicating an earlier timing of the internal circadian pacemaker). ...In the current study, we examined whether the chronotype, which is influenced by the circadian rhythm, is also earlier. In addition, we explored whether chronotype is related to disease activity and patient-reported outcomes.
Methods
The chronotype (Munich Chronotype Questionnaire) of patients with RA (
n
= 121; mean age 60 years, 73% female) was compared with that of subjects from the general population (norm group;
n
= 1695) with a one-sample
t
test. In addition, we investigated chronotype in relation to disease activity (Disease Activity Score; DAS), reported morning stiffness, fatigue (Checklist Individual Strength), and health-related quality of life (RAND-36).
Results
The chronotype of patients with RA was, on average, 23 min (95% CI, 15 to 31 min) earlier than that of the norm group (
t
(115) = − 5.901,
p
< 0.001,
d
= 0.55). Chronotype was not related to disease activity or patient-reported outcomes (
p
> 0.05).
Conclusion
As expected, chronotype was earlier in RA patients. However, in this correlational study, chronotype was not related to disease activity or patient-reported outcomes. An experimental study is needed to examine whether delaying the circadian rhythm has a positive influence on these outcomes. This insight could improve our understanding of the pathophysiology of RA and contribute to exploring new treatment possibilities.
Key Points
• This is the first study examining chronotype in patients with rheumatoid arthritis, and how chronotype relates to disease activity and patient-reported outcomes.
• We found an earlier chronotype in patients with rheumatoid arthritis than in subjects from the general population.
• In this correlational study, chronotype was not related to disease activity or patient-reported outcomes. An experimental study is needed to examine whether delaying the circadian rhythm positively influences these outcomes.
Background: This study was designed to investigate: (i) parent–adolescent communication in families of cancer patients; (ii) relationships between parent–adolescent communication and posttraumatic ...stress symptoms (PTSS) in adolescent children; and (iii) associations between parents' illness characteristics and parent–adolescent communication. Patients and methods: A total of 212 adolescents completed the Impact of Event Scale and Parent–Adolescent Communication Scale. Results: Adolescents communicated less openly with mothers with cancer than controls with mothers; this was the only significant difference with the reference group. Daughters communicated more openly with ill parents than with healthy parents. More open communication with healthy parents was related to fewer PTSS in daughters. More problem communication with both parents was related to more PTSS in both sons and daughters. Sons reported more problems in communication with ill parents in case of more intensive treatment or recurrent disease. Daughters experienced less open communication with both parents when ill parents received more intensive treatment. Time since diagnosis was not related to parent–adolescent communication. Multivariate analyses showed that communication patterns specifically affected PTSS of daughters. Problem communication with the healthy parent was the strongest predictor of intrusion while problem communication with the ill parents was the strongest predictor of avoidance. Conclusions: Parent–adolescent communication in families of cancer patients differs little from that in families not confronted with parental cancer. Problem communication outweighed lack of openness with respect to development of PTSS. Recurrent disease and intensive treatment regimens affected parent–adolescent communication negatively.
Staphylococcus aureus is a versatile opportunistic pathogen, causing disease in human and animal species. Its pathogenicity is linked to the ability of S. aureus to secrete immunomodulatory ...molecules. These evasion proteins bind to host receptors or their ligands, resulting in inhibitory effects through high affinity protein-protein interactions. Staphylococcal evasion molecules are often species-specific due to differences in host target proteins between species. We recently solved the crystal structure of murine TLR2 in complex with immunomodulatory molecule staphylococcal superantigen-like protein 3 (SSL3), which revealed the essential residues within SSL3 for TLR2 inhibition. In this study we aimed to investigate the molecular basis of the interaction on the TLR2 side. The SSL3 binding region on murine TLR2 was compared to that of other species through sequence alignment and homology modeling, which identified interspecies differences. To examine whether this resulted in altered SSL3 activity on the corresponding TLR2s, bovine, equine, human, and murine TLR2 were stably expressed in HEK293T cells and the ability of SSL3 to inhibit TLR2 was assessed. We found that SSL3 was unable to inhibit bovine TLR2. Subsequent loss and gain of function mutagenesis showed that the lack of inhibition is explained by the absence of two tyrosine residues in bovine TLR2 that play a prominent role in the SSL3-TLR2 interface. We found no evidence for the existence of allelic SSL3 variants that have adapted to the bovine host. Thus, within this paper we reveal the molecular determinants of the TLR2-SSL3 interaction which adds to our understanding of staphylococcal host specificity.
Introduction
C1q is an essential part of the classical pathway of complement activation. Genetic deficiencies, caused by homozygous mutations in one of the C1q genes, are rare and are strongly ...associated with development of systemic lupus erythematosus (SLE). Here we describe a C1q-deficient patient with a compound heterozygous mutation.
Material and methods
Serum was analysed with enzyme-linked immunosorbent assay (ELISA) and Western blot for the presence of C1q, and DNA and RNA sequencing was performed to identify the mutations and confirm that these were located on different chromosomes.
Results
The medical history of the patient includes SLE diagnosis at age 11 years with cerebral involvement at age 13, various infections, osteonecrosis and hemophagocytic syndrome. Using ELISA and Western blot, we confirmed the absence of C1q in the serum of the patient. Using DNA sequencing, two mutations in the C1QC gene were identified: c.100G > A p.(Gly34Arg) and c.205C > T p.(Arg69X). With RNA sequencing we confirmed that the mutations are located on different chromosomes.
Discussion
The patient described in this case report has a compound heterozygous mutation in C1QC resulting in C1q deficiency.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, OILJ, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Purpose
Incisional hernia is a frequent complication of abdominal surgery (incidence 2–20%). Diagnosis by physical examination is sometimes difficult, especially in small incisional hernias or in ...obese patients. The additional diagnostic value of standardized ultrasonography was evaluated in this prospective study.
Methods
A total of 456 patients participating in a randomized trial comparing two suture materials for closure of the abdominal fascia underwent physical examination and ultrasonography at 6-month intervals. Wound complaints and treatment of incisional hernia were also noted. Statistical analysis was performed using the Chi-squared and Fisher’s exact tests (SPSS). Interest variability analysis was performed.
Results
During a median follow-up of 31 months, 103 incisional hernias were found. A total of 82 incisional hernias were found by physical examination and an additional 21 with ultrasonography. Six of these additional hernias were symptomatic and only one of the additional hernias received operative treatment. The false-negative rates for physical examination and ultrasonography were 25.3 and 24.4%, respectively. Interest variability was low, with a Kappa of 0.697 (
P
< 0.001).
Conclusions
There are no clear diagnostic criteria for incisional hernia available in the literature. Standardized combination of ultrasonography with physical examination during follow-up yields a significant number of, mostly asymptomatic, hernias, which would not be found using physical examination alone. This is especially relevant in research settings.
Objective
Genetic factors account for an estimated 45–58% of the variance in joint destruction in rheumatoid arthritis (RA). The serine proteinase granzyme B induces target cell apoptosis, and ...several in vitro studies suggest that granzyme B is involved in apoptosis of chondrocytes. Serum levels of granzyme B are increased in RA and are also associated with radiographic erosions. The aim of this study was to investigate GZMB as a candidate gene accounting for the severity of joint destruction in RA.
Methods
A total of 1,418 patients with 4,885 radiograph sets of the hands and feet from 4 independent cohorts were studied. First, explorative analyses were performed in 600 RA patients in the Leiden Early Arthritis Clinic cohort. Fifteen single‐nucleotide polymorphisms (SNPs) tagging GZMB were tested. Significantly associated SNPs were genotyped in data sets representing patients from the Groningen, Sheffield, and Lund cohorts. In each data set, the relative increase in the annual rate of progression in the presence of a genotype was assessed. Data were summarized in a meta‐analysis. The association of GZMB with the RNA expression level of the GZMB genomic region was tested by mapping expression quantitative trait loci (QTLs) on 1,469 whole blood samples.
Results
SNP rs8192916 was significantly associated with the rate of joint destruction in the first cohort and in the meta‐analysis of all data sets. Patients homozygous for the minor allele of rs8192916 had a higher rate of joint destruction per year compared with other patients (P = 7.8 × 10−4). Expression QTL of GZMB identified higher expression in the presence of the minor allele of rs8192916 (P = 2.27 × 10−5).
Conclusion
SNP rs8192916 located in GZMB is associated with the progression of joint destruction in RA as well as with RNA expression in whole blood.
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