Patients with atopic dermatitis (AD) have an abnormal skin barrier and are frequently colonized by S. aureus. In this study we investigated if S. aureus penetrates the epidermal barrier of subjects ...with AD and sought to understand the mechanism and functional significance of this entry. S. aureus was observed to be more abundant in the dermis of lesional skin from AD patients. Bacterial entry past the epidermis was observed in cultured human skin equivalents and in mice but was found to be increased in the skin of cathelicidin knockout and ovalbumin-sensitized filaggrin mutant mice. S. aureus penetration through the epidermis was dependent on bacterial viability and protease activity, because killed bacteria and a protease-null mutant strain of S. aureus were unable to penetrate. Entry of S. aureus directly correlated with increased expression of IL-4, IL-13, IL-22, thymic stromal lymphopoietin, and other cytokines associated with AD and with decreased expression of cathelicidin. These data illustrate how abnormalities of the epidermal barrier in AD can alter the balance of S. aureus entry into the dermis and provide an explanation for how such dermal dysbiosis results in increased inflammatory cytokines and exacerbation of disease.
The microbiome can promote or disrupt human health by influencing both adaptive and innate immune functions. We tested whether bacteria that normally reside on human skin participate in host defense ...by killing
, a pathogen commonly found in patients with atopic dermatitis (AD) and an important factor that exacerbates this disease. High-throughput screening for antimicrobial activity against
was performed on isolates of coagulase-negative
(CoNS) collected from the skin of healthy and AD subjects. CoNS strains with antimicrobial activity were common on the normal population but rare on AD subjects. A low frequency of strains with antimicrobial activity correlated with colonization by
The antimicrobial activity was identified as previously unknown antimicrobial peptides (AMPs) produced by CoNS species including
and
These AMPs were strain-specific, highly potent, selectively killed
, and synergized with the human AMP LL-37. Application of these CoNS strains to mice confirmed their defense function in vivo relative to application of nonactive strains. Strikingly, reintroduction of antimicrobial CoNS strains to human subjects with AD decreased colonization by
These findings show how commensal skin bacteria protect against pathogens and demonstrate how dysbiosis of the skin microbiome can lead to disease.
CRISPR-associated transposons (CASTs) are Tn7-like elements that are capable of RNA-guided DNA integration. Although structural data are known for nearly all core transposition components, the ...transposase component, TnsB, remains uncharacterized. Using cryo-electron microscopy (cryo-EM) structure determination, we reveal the conformation of TnsB during transposon integration for the type V-K CAST system from
(ShCAST). Our structure of TnsB is a tetramer, revealing strong mechanistic relationships with the overall architecture of RNaseH transposases/integrases in general, and in particular the MuA transposase from bacteriophage Mu. However, key structural differences in the C-terminal domains indicate that TnsB's tetrameric architecture is stabilized by a different set of protein-protein interactions compared with MuA. We describe the base-specific interactions along the TnsB binding site, which explain how different CAST elements can function on cognate mobile elements independent of one another. We observe that melting of the 5' nontransferred strand of the transposon end is a structural feature stabilized by TnsB and furthermore is crucial for donor-DNA integration. Although not observed in the TnsB strand-transfer complex, the C-terminal end of TnsB serves a crucial role in transposase recruitment to the target site. The C-terminal end of TnsB adopts a short, structured 15-residue "hook" that decorates TnsC filaments. Unlike full-length TnsB, C-terminal fragments do not appear to stimulate filament disassembly using two different assays, suggesting that additional interactions between TnsB and TnsC are required for redistributing TnsC to appropriate targets. The structural information presented here will help guide future work in modifying these important systems as programmable gene integration tools.
To review cases of suppurative osteomyelitis of the jaws treated at the Massachusetts General Hospital (Boston, MA) over a 10-year period, evaluate specifics of disease presentation, and answer the ...clinical question: are there identifiable variables associated with treatment outcome?
A retrospective cohort study was completed using patients treated for suppurative osteomyelitis of the jaws at the Massachusetts General Hospital from April 2006 to October 2016. Inclusion criteria were a diagnosis of suppurative osteomyelitis of the jaw, age older than 18 years, and complete medical records. Patients with nonsuppurative disease, radiation history, or antiresorptive exposure were excluded. Candidate variables included demographic information, medical and dental history, presenting signs and symptoms, and radiologic and laboratory findings. The outcome variable was successful treatment, defined as resolution of symptoms and radiographic evidence of healing after initial treatment. Appropriate statistical analyses were performed with significance set a P value less than .05.
Forty-two patients met the inclusion criteria. Mean age was 53 years (range, 20 to 80 yr) and 26 were women (62%). Common comorbidities included cardiovascular disease (52%), tobacco use (45%), and psychiatric disorders (45%). Pain (90%), swelling (86%), and neurosensory change (50%) were the most common findings. Common microbacterial isolates included Streptococcus milleri (74%) and coagulase-negative Staphylococcus species (43%), which showed marked antibiotic resistance. Surgical debridement was the most common intervention (93%). Successful treatment was found in 86%. Of 6 persistent cases, 4 resolved with a second debridement and continued antibiotics and 2 required resection. Increased white blood cell (WBC) count at presentation (P = .005) and associated psychiatric diagnoses (P = .037) were statistically associated with unsuccessful initial treatment.
The results of this study indicate that antibiotic resistance is commonly encountered in this patient population, although it was not associated with unsuccessful outcome. Patients presenting with increased WBC count and concurrent psychiatric comorbidities required protracted treatment.
We report the discovery that strains of
produce 6-
-hydroxyaminopurine (6-HAP), a molecule that inhibits DNA polymerase activity. In culture, 6-HAP selectively inhibited proliferation of tumor lines ...but did not inhibit primary keratinocytes. Resistance to 6-HAP was associated with the expression of mitochondrial amidoxime reducing components, enzymes that were not observed in cells sensitive to this compound. Intravenous injection of 6-HAP in mice suppressed the growth of B16F10 melanoma without evidence of systemic toxicity. Colonization of mice with an
strain producing 6-HAP reduced the incidence of ultraviolet-induced tumors compared to mice colonized by a control strain that did not produce 6-HAP.
strains producing 6-HAP were found in the metagenome from multiple healthy human subjects, suggesting that the microbiome of some individuals may confer protection against skin cancer. These findings show a new role for skin commensal bacteria in host defense.
Cases of iatrogenic cerebral amyloid angiopathy (CAA) have been increasingly reported recently, particularly those associated with neurosurgery. Preclinical studies have shown taxifolin to be ...promising for treating CAA. We describe a young 42-year-old man with a history of childhood traumatic brain injury that required a craniotomy for hematoma evacuation. He later presented with recurrent lobar intracerebral hemorrhage (ICH) decades later, which was histologically confirmed to be CAA. Serial
C-Pittsburgh compound B positron emission tomography (
C-PiB-PET) imaging showed a 24% decrease in global standardized uptake value ratio (SUVR) at 10 months after taxifolin use. During this period, the patient experienced clinical improvement with improved consciousness and reduced recurrent ICH frequency, which may be partly attributable to the potential amyloid-β (Aβ) clearing the effect of taxifolin. However, this effect seemed to have diminished at 15 months, CAA should be considered in young patients presenting with recurrent lobar ICH with a history of childhood neurosurgery, and serial
C-PiB-PET scans warrant further validation as a strategy for monitoring treatment response in CAA for candidate Aβ-clearing therapeutic agents such as taxifolin.
Germline mutations in BRCA2 have been linked to a higher risk of prostate cancer (PCa), and high frequency of BRCA1 and BRCA2 (BRCA1/2) gene alterations was recently reported in metastatic ...castration-resistant PCa specimens. Mutations in BRCA2 vary in racial and ethnic groups including African-American (AA) and Caucasian-American (CA) populations.
BRCA1 and BRCA2 genes were sequenced (Ion AmpliSeq targeted sequencing) in archived blood DNA specimens in 1240 PCa patients, including 30% AA patients, in three different cohorts: localized early stage (T2) PCa (N = 935); advanced PCa (50% T3-4) (N = 189); and metastatic PCa (N = 116). The sequences were analyzed for known and novel mutations in BRCA1/2. Statistical analyses were performed to determine associations of the mutations with clinico-pathological parameters.
BRCA2 mutations with known pathogenic annotation were significantly more prevalent in men with advanced and metastatic PCa (3.1%) compared to patients with an organ-confined disease (0.7%). AA patients carried more frequently BRCA1/2 variants of unknown significance (VUS) when compared to Caucasian Americans (4.6 vs. 1.6%, respectively). Significantly, pathogenic BRCA2 mutations in men with localized early stage PCa increased the risk of distant metastasis.
Germline variants of unknown significance in BRCA1/2 are more frequent in AA than CA PCa patients; however, the prevalence of pathogenic mutations were similar across the races. Patients carrying BRCA2 pathogenic mutations are more likely to progress to metastasis.
Granulomatous mastitis due to
is an increasingly recognised cause of an indolent and distressing mastitis in non-lactating females. This slow-growing lipophilic organism is not reliably isolated ...using routine culture methods. A novel selective culture medium (CKSM) is designed to optimise the isolation of this organism from clinical specimens.
CKSM contains 10% galactose and Tween 80 (10%) to enhance the growth of
, fosfomycin (100 µg/mL) to suppress the other bacteria, and differentiate
from non-
lipophilic corynebacteria by esculin hydrolysis. The medium was evaluated for its ability to support the growth of
, selection and differentiation of
from other bacteria in non-sterile clinical specimens.
grew as 1-2 mm colonies with black halo on CKSM within 72 hours of incubation, compared with barely visible pinpoint colonies on routine blood agars. During the four-month period of evaluation with 8896 respiratory specimens, 103 breast specimens, 1903 female genital tract specimens, 617 newborn surface swabs and 10 011 miscellaneous specimens, 186
were isolated, including 127 (1.4%) respiratory and 59 (0.5%) miscellaneous specimens, 184 of them were found only on CKSM. Besides the three (2.9%) positive breast specimens, 27 (1.4%) high vaginal and endocervical swabs, and 11 (1.8%) surface swabs of newborns were positive for
.
CKSM is a useful addition to routine agar media for the isolation of
and will be helpful for studying the epidemiology and transmission of this unusual
causing granulomatous mastitis.
The mechanism of tumorigenicity potentially evolved in mesenchymal stem cells (MSCs) remains elusive, resulting in inconsistent clinical application efficacy. We hypothesized that subclones in MSCs ...contribute to their tumorgenicity, and we approached MSC-subclones at the single-cell level.
MSCs were cultured in an osteogenic differentiation medium and harvested on days 12, 19, and 25 for cell differentiation analysis using Alizarin Red and followed with the single-cell transcriptome.
Single-cell RNA-seq analysis reveals a discrete cluster of MSCs during osteogenesis, including differentiation-resistant MSCs (DR-MSCs), differentiated osteoblasts (DO), and precursor osteoblasts (PO). The DR-MSCs population resembled cancer initiation cells and were subjected to further analysis of the yes associated protein 1 (YAP1) network. Verteporfin was also used for YAP1 inhibition in cancer cell lines to confirm the role of YAP1 in MSC--involved tumorigenicity. Clinical data from various cancer types were analyzed to reveal relationships among YAP1, OCT4, and CDH6 in MSC--involved tumorigenicity. The expression of cadherin 6 (CDH6), octamer-binding transcription factor 4 (OCT4), and YAP1 expression was significantly upregulated in DR-MSCs compared to PO and DO. YAP1 inhibition by Verteporfin accelerated the differentiation of MSCs and suppressed the expression of YAP1, CDH6, and OCT4. A survey of 56 clinical cohorts revealed a high degree of co-expression among CDH6, YAP1, and OCT4 in various solid tumors. YAP1 inhibition also down-regulated HeLa cell viability and gradually inhibited YAP1 nuclear localization while reducing the transcription of CDH6 and OCT4.
We used single-cell sequencing to analyze undifferentiated MSCs and to discover a carcinogenic pathway in single-cell MSCs of differentiated resistance subclones.
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