In South Korea, a November 2021 outbreak caused by severe acute respiratory syndrome coronavirus 2 Omicron variant originated from 1 person with an imported case and spread to households, ...kindergartens, workplaces, restaurants, and hospitals, resulting in 11 clusters within 3 weeks. An epidemiologic curve indicated rapid community transmission of the Omicron variant.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Objective
Increased protein phosphatase magnesium‐dependent 1A (PPM1A) levels in patients with ankylosing spondylitis regulate osteoblast differentiation in bony ankylosis; however, the potential ...mechanisms that regulate osteoclast differentiation in relation to abnormal bone formation remain unclear. This study was undertaken to investigate the relationship of PPM1A to osteoclast differentiation by generating conditional gene‐knockout (PPM1Afl/fl;LysM‐Cre) mice and evaluating their bone phenotype.
Methods
The bone phenotypes of LysM‐Cre mice (n = 6) and PPM1Afl/fl;LysM‐Cre mice (n = 6) were assessed by micro–computed tomography. Osteoclast differentiation was induced by culturing bone marrow–derived macrophages in the presence of RANKL and macrophage colony‐stimulating factor (M‐CSF), and was evaluated by counting tartrate‐resistant acid phosphatase–positive multinucleated cells. Levels of messenger RNA for PPM1A, RANK, and osteoclast‐specific genes were examined by real‐time quantitative polymerase chain reaction, and protein levels were determined by Western blotting. Surface RANK expression was analyzed by fluorescence flow cytometry.
Results
The PPM1Afl/fl;LysM‐Cre mice displayed reduced bone mass (P < 0.001) and increased osteoclast differentiation (P < 0.001) and osteoclast‐specific gene expression (P < 0.05) compared with their LysM‐Cre littermates. Mechanistically, reduced PPM1A function in osteoclast precursors in PPM1Afl/fl;LysM‐Cre mice induced osteoclast lineage commitment by up‐regulating RANK expression (P < 0.01) via p38 MAPK activation in response to M‐CSF. PPM1A expression in macrophages was decreased by Toll‐like receptor 4 activation (P < 0.05). The Ankylosing Spondylitis Disease Activity Score was negatively correlated with the expression of PPM1A in peripheral blood mononuclear cells from patients with axial spondyloarthritis (SpA) (γ = −0.7072, P < 0.0001).
Conclusion
The loss of PPM1A function in osteoclast precursors driven by inflammatory signals contributes to osteoclast lineage commitment and differentiation by elevating RANK expression, reflecting a potential role of PPM1A in dynamic bone metabolism in axial SpA.
Parkin dysfunction associated with the progression of parkinsonism contributes to a progressive systemic skeletal disease characterized by low bone mineral density. However, the role of parkin in ...bone remodeling has not yet been elucidated in detail.
We observed that decreased parkin in monocytes is linked to osteoclastic bone-resorbing activity. siRNA-mediated knockdown of parkin significantly enhanced the bone-resorbing activity of osteoclasts (OCs) on dentin without any changes in osteoblast differentiation. Moreover, Parkin-deficient mice exhibited an osteoporotic phenotype with a lower bone volume accompanied by increased OC-mediated bone-resorbing capacity displaying increased acetylation of α-tubulin compared to wild-type (WT) mice. Notably, compared to WT mice, the Parkin-deficient mice displayed increased susceptibility to inflammatory arthritis, reflected by a higher arthritis score and a marked bone loss after arthritis induction using K/BxN serum transfer, but not ovariectomy-induced bone loss. Intriguingly, parkin colocalized with microtubules and parkin-depleted-osteoclast precursor cells (Parkin
OCPs) displayed augmented ERK-dependent acetylation of α-tubulin due to failure of interaction with histone deacetylase 6 (HDAC6), which was promoted by IL-1β signaling. The ectopic expression of parkin in Parkin
OCPs limited the increase in dentin resorption induced by IL-1β, accompanied by the reduced acetylation of α-tubulin and diminished cathepsin K activity.
These results indicate that a deficiency in the function of parkin caused by a decrease in parkin expression in OCPs under the inflammatory condition may enhance inflammatory bone erosion by altering microtubule dynamics to maintain OC activity.
Coupling is the process that links bone resorption to bone formation in a temporally and spatially coordinated manner within the remodeling cycle. Several lines of evidence point to the critical ...roles of osteoclast-derived coupling factors in the regulation of osteoblast performance. Here, we used a fractionated secretomic approach and identified the axon-guidance molecule SLIT3 as a clastokine that stimulated osteoblast migration and proliferation by activating β-catenin. SLIT3 also inhibited bone resorption by suppressing osteoclast differentiation in an autocrine manner. Mice deficient in Slit3 or its receptor, Robo1, exhibited osteopenic phenotypes due to a decrease in bone formation and increase in bone resorption. Mice lacking Slit3 specifically in osteoclasts had low bone mass, whereas mice with either neuron-specific Slit3 deletion or osteoblast-specific Slit3 deletion had normal bone mass, thereby indicating the importance of SLIT3 as a local determinant of bone metabolism. In postmenopausal women, higher circulating SLIT3 levels were associated with increased bone mass. Notably, injection of a truncated recombinant SLIT3 markedly rescued bone loss after an ovariectomy. Thus, these results indicate that SLIT3 plays an osteoprotective role by synchronously stimulating bone formation and inhibiting bone resorption, making it a potential therapeutic target for metabolic bone diseases.
Summary Background In 2015, a large outbreak of Middle East respiratory syndrome coronavirus (MERS-CoV) infection occurred following a single patient exposure in an emergency room at the Samsung ...Medical Center, a tertiary-care hospital in Seoul, South Korea. We aimed to investigate the epidemiology of MERS-CoV outbreak in our hospital. Methods We identified all patients and health-care workers who had been in the emergency room with the index case between May 27 and May 29, 2015. Patients were categorised on the basis of their exposure in the emergency room: in the same zone as the index case (group A), in different zones except for overlap at the registration area or the radiology suite (group B), and in different zones (group C). We documented cases of MERS-CoV infection, confirmed by real-time PCR testing of sputum samples. We analysed attack rates, incubation periods of the virus, and risk factors for transmission. Findings 675 patients and 218 health-care workers were identified as contacts. MERS-CoV infection was confirmed in 82 individuals (33 patients, eight health-care workers, and 41 visitors). The attack rate was highest in group A (20% 23/117 vs 5% 3/58 in group B vs 1% 4/500 in group C; p<0·0001), and was 2% (5/218) in health-care workers. After excluding nine cases (because of inability to determine the date of symptom onset in six cases and lack of data from three visitors), the median incubation period was 7 days (range 2–17, IQR 5–10). The median incubation period was significantly shorter in group A than in group C (5 days IQR 4–8 vs 11 days 6–12; p<0·0001). There were no confirmed cases in patients and visitors who visited the emergency room on May 29 and who were exposed only to potentially contaminated environment without direct contact with the index case. The main risk factor for transmission of MERS-CoV was the location of exposure. Interpretation Our results showed increased transmission potential of MERS-CoV from a single patient in an overcrowded emergency room and provide compelling evidence that health-care facilities worldwide need to be prepared for emerging infectious diseases. Funding None.
Akkermansia muciniphila has received great attention because of its beneficial roles in gut health by regulating gut immunity, promoting intestinal epithelial development, and improving barrier ...integrity. However, A. muciniphila-derived functional molecules regulating gut health are not well understood. Microbiome-secreted proteins act as key arbitrators of host-microbiome crosstalk through interactions with host cells in the gut and are important for understanding host-microbiome relationships. Herein, we report the biological function of Amuc_1409, a previously uncharacterised A. muciniphila-secreted protein. Amuc_1409 increased intestinal stem cell (ISC) proliferation and regeneration in ex vivo intestinal organoids and in vivo models of radiation- or chemotherapeutic drug-induced intestinal injury and natural aging with male mice. Mechanistically, Amuc_1409 promoted E-cadherin/β-catenin complex dissociation via interaction with E-cadherin, resulting in the activation of Wnt/β-catenin signaling. Our results demonstrate that Amuc_1409 plays a crucial role in intestinal homeostasis by regulating ISC activity in an E-cadherin-dependent manner and is a promising biomolecule for improving and maintaining gut health.
Fructose intake is known to induce obesity, insulin resistance, metabolic syndrome, and nonalcoholic fatty liver disease (NAFLD). We aimed to evaluate the effects of fructose drinking on gut ...leakiness, endotoxemia, and NAFLD and study the underlying mechanisms in rats, mice, and T84 colon cells. Levels of ileum junctional proteins, oxidative stress markers, and apoptosis‐related proteins in rodents, T84 colonic cells, and human ileums were determined by immunoblotting, immunoprecipitation, and immunofluorescence analyses. Fructose drinking caused microbiome change, leaky gut, and hepatic inflammation/fibrosis with increased levels of nitroxidative stress marker proteins cytochrome P450‐2E1 (CYP2E1), inducible nitric oxide synthase, and nitrated proteins in small intestine and liver of rodents. Fructose drinking significantly elevated plasma bacterial endotoxin levels, likely resulting from decreased levels of intestinal tight junction (TJ) proteins (zonula occludens 1, occludin, claudin‐1, and claudin‐4), adherent junction (AJ) proteins (β‐catenin and E‐cadherin), and desmosome plakoglobin, along with α‐tubulin, in wild‐type rodents, but not in fructose‐exposed Cyp2e1‐null mice. Consistently, decreased intestinal TJ/AJ proteins and increased hepatic inflammation with fibrosis were observed in autopsied obese people compared to lean individuals. Furthermore, histological and biochemical analyses showed markedly elevated hepatic fibrosis marker proteins in fructose‐exposed rats compared to controls. Immunoprecipitation followed by immunoblot analyses revealed that intestinal TJ proteins were nitrated and ubiquitinated, leading to their decreased levels in fructose‐exposed rats. Conclusion: These results showed that fructose intake causes protein nitration of intestinal TJ and AJ proteins, resulting in increased gut leakiness, endotoxemia, and steatohepatitis with liver fibrosis, at least partly, through a CYP2E1‐dependent manner.
LRRK2, a Parkinson's disease associated gene, is highly expressed in microglia in addition to neurons; however, its function in microglia has not been evaluated. Using Lrrk2 knockdown (Lrrk2-KD) ...murine microglia prepared by lentiviral-mediated transfer of Lrrk2-specific small inhibitory hairpin RNA (shRNA), we found that Lrrk2 deficiency attenuated lipopolysaccharide (LPS)-induced mRNA and/or protein expression of inducible nitric oxide synthase, TNF-α, IL-1β and IL-6. LPS-induced phosphorylation of p38 mitogen-activated protein kinase and stimulation of NF-κB-responsive luciferase reporter activity was also decreased in Lrrk2-KD cells. Interestingly, the decrease in NF-κB transcriptional activity measured by luciferase assays appeared to reflect increased binding of the inhibitory NF-κB homodimer, p50/p50, to DNA. In LPS-responsive HEK293T cells, overexpression of the human LRRK2 pathologic, kinase-active mutant G2019S increased basal and LPS-induced levels of phosphorylated p38 and JNK, whereas wild-type and other pathologic (R1441C and G2385R) or artificial kinase-dead (D1994A) LRRK2 mutants either enhanced or did not change basal and LPS-induced p38 and JNK phosphorylation levels. However, wild-type LRRK2 and all LRRK2 mutant variants equally enhanced NF-κB transcriptional activity. Taken together, these results suggest that LRRK2 is a positive regulator of inflammation in murine microglia, and LRRK2 mutations may alter the microenvironment of the brain to favor neuroinflammation.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Although archaea, Gram-negative bacteria, and mammalian cells constitutively secrete membrane vesicles (MVs) as a mechanism for cell-free intercellular communication, this cellular process has been ...overlooked in Gram-positive bacteria. Here, we found for the first time that Gram-positive bacteria naturally produce MVs into the extracellular milieu. Further characterizations showed that the density and size of Staphylococcus aureus-derived MVs are both similar to those of Gram-negative bacteria. With a proteomics approach, we identified with high confidence a total of 90 protein components of S. aureus-derived MVs. In the group of identified proteins, the highly enriched extracellular proteins suggested that a specific sorting mechanism for vesicular proteins exists. We also identified proteins that facilitate the transfer of proteins to other bacteria, as well to eliminate competing organisms, antibiotic resistance, pathological functions in systemic infections, and MV biogenesis. Taken together, these observations suggest that the secretion of MVs is an evolutionally conserved, universal process that occurs from simple organisms to complex multicellular organisms. This information will help us not only to elucidate the biogenesis and functions of MVs, but also to develop therapeutic tools for vaccines, diagnosis, and antibiotics effective against pathogenic strains of Gram-positive bacteria.
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