Mef2c regulates bone mass through Sost-dependent and -independent mechanisms

Mef2c is a transcription factor that mediates key cellular behaviors that promote endochondral ossification and bone formation. Previously, Mef2c has been shown to regulate Sost transcription via its osteocyte-specific enhancer, ECR5, and conditional deletions of Mef2cfl/fl with either Col1-Cre or Dmp1-Cre produced generalized high bone mass (HBM) consistent with Van Buchem Disease phenotypes. However, Sost-/-; Mef2cfl/fl; Dmp1-Cre mice produced a significantly higher bone mass phenotype that Sost-/- alone suggesting that Mef2c modulates bone mass through additional mechanisms, independent of Sost. To identify new Mef2c transcriptional targets important in bone metabolism, we profiled gene expression by single-cell RNA sequencing in subpopulations of cells isolated from Mef2cfl/fl; Dmp1-Cre and Mef2cfl/fl; Bglap-Cre femurs, both strains exhibiting similar high bone mass phenotypes. However, we found Mef2cfl/fl; Bglap-Cre to also display a growth plate defect characterized by an expansion of several osteoprogenitor subpopulations. Differential gene expression analysis identified a total of 96 up- and 2434 down- regulated genes in Mef2cfl/fl; Bglap-Cre and 176 up- and 1041 down- regulated genes in Mef2cfl/fl; Dmp1-Cre bone cell subpopulations compared to wildtype mice. Mef2c deletion affected the transcriptomes across several cell types including mesenchymal progenitors (MP), osteoprogenitors (OSP), osteoblast (OB), and osteocyte (OCY) subpopulations. Several energy metabolism genes such as Uqcrb, Ndufv2, Ndufs3, Ndufa13, Ndufb9, Ndufb5, Cox6a1, Cox5a, Atp5o, Atp5g2, Atp5b, Atp5 were significantly down regulated in Mef2c-deficient OBs and OCYs, in both strains. Binding motif analysis of promoter regions of differentially expressed genes identified Mef2c binding in Bone Sialoprotein (BSP/Ibsp), a gene known to cause increased trabecular BV/TV in the femurs of Ibsp-/- mice. Immunohistochemical analysis confirmed the absence of Ibsp protein in OBs and OCYs. These findings suggests that the HBM in Sost-/-; Mef2cfl/fl; Dmp1-Cre is caused by a multitude of transcriptional changes in genes that regulate bone formation, two of which are Sost and Ibsp.

Loss of Cadherin-11 in pancreatic ductal adenocarcinoma alters tumor-immune microenvironment

Pancreatic ductal adenocarcinoma (PDAC) is one of the top five deadliest forms of cancer with very few treatment options. The 5-year survival rate for PDAC is 10% following diagnosis. Cadherin 11 (Cdh11), a cell-to-cell adhesion molecule, has been suggested to promote tumor growth and immunosuppression in PDAC, and Cdh11 inhibition significantly extended survival in mice with PDAC. However, the mechanisms by which Cdh11 deficiency influences PDAC progression and anti-tumor immune responses have yet to be fully elucidated. To investigate Cdh11-deficiency induced changes in PDAC tumor microenvironment (TME), we crossed p48-Cre; LSL-KrasG12D/+; LSL-Trp53R172H/+ (KPC) mice with Cdh11+/- mice and performed single-cell RNA sequencing (scRNA-seq) of the non-immune (CD45-) and immune (CD45+) compartment of KPC tumor-bearing Cdh11 proficient (KPC-Cdh11+/+) and Cdh11 deficient (KPC-Cdh11+/-) mice. Our analysis showed that Cdh11 is expressed primarily in cancer-associated fibroblasts (CAFs) and at low levels in epithelial cells undergoing epithelial-to-mesenchymal transition (EMT). Cdh11 deficiency altered the molecular profile of CAFs, leading to a decrease in the expression of myofibroblast markers such as Acta2 and Tagln and cytokines such as Il6, Il33 and Midkine (Mdk). We also observed a significant decrease in the presence of monocytes/macrophages and neutrophils in KPC-Cdh11+/- tumors while the proportion of T cells was increased. Additionally, myeloid lineage cells from Cdh11-deficient tumors had reduced expression of immunosuppressive cytokines that have previously been shown to play a role in immune suppression. In summary, our data suggests that Cdh11 deficiency significantly alters the fibroblast and immune microenvironments and contributes to the reduction of immunosuppressive cytokines, leading to an increase in anti-tumor immunity and enhanced survival.

Host tracheal and intestinal microbiomes inhibit Coccidioides growth in vitro

Coccidioidomycosis, also known as Valley fever, is a disease caused by the fungal pathogen Coccidioides. Unfortunately, patients are often misdiagnosed with bacterial pneumonia leading to inappropriate antibiotic treatment. Soil bacteria B. subtilis-like species exhibits antagonistic properties against Coccidioides in vitro; however, the antagonistic capabilities of host microbiota against Coccidioides are unexplored. We sought to examine the potential of the tracheal and intestinal microbiomes to inhibit the growth of Coccidioides in vitro. We hypothesized that an uninterrupted lawn of microbiota obtained from antibiotic-free mice would inhibit the growth of Coccidioides while partial in vitro depletion through antibiotic disk diffusion assays would allow a niche for fungal growth. We observed that the microbiota grown on 2xGYE (GYE) and CNA w/ 5% sheep's blood agar (5%SB-CNA) inhibited the growth of Coccidioides, but that grown on chocolate agar does not. Partial depletion of the microbiota through antibiotic disk diffusion revealed that microbiota depletion leads to diminished inhibition and comparable growth of Coccidioides growth to controls. To characterize the bacteria grown and narrow down potential candidates contributing to the inhibition of Coccidioides, 16s rRNA sequencing of tracheal and intestinal agar cultures and murine lung extracts was performed. The identity of host bacteria that may be responsible for this inhibition was revealed. The results of this study demonstrate the potential of the host microbiota to inhibit the growth of Coccidioides in vitro and suggest that an altered microbiome through antibiotic treatment could negatively impact effective fungal clearance and allow a niche for fungal growth in vivo.

Single-cell RNA-Seq reveals changes in immune landscape in post-traumatic osteoarthritis

Osteoarthritis (OA) is the most common joint disease, affecting over 300 million people world-wide. Accumulating evidence attests to the important roles of the immune system in OA pathogenesis. Understanding the role of various immune cells in joint degeneration or joint repair after injury is vital for improving therapeutic strategies for treating OA. Post-traumatic osteoarthritis (PTOA) develops in ~50% of individuals who have experienced an articular trauma like an anterior cruciate ligament (ACL) rupture. Here, using the high resolution of single-cell RNA sequencing, we delineated the temporal dynamics of immune cell accumulation in the mouse knee joint after ACL rupture. Our study identified multiple immune cell types in the joint including neutrophils, monocytes, macrophages, B cells, T cells, NK cells and dendritic cells. Monocytes and macrophage populations showed the most dramatic changes after injury. Further characterization of monocytes and macrophages reveled 9 major subtypes with unique transcriptomics signatures, including a tissue resident Lyve1hiFolr2hi macrophage population and Trem2hiFcrls+ recruited macrophages, both showing enrichment for phagocytic genes and growth factors such as Igf1, Pdgfa and Pdgfc. We also identified several genes induced or repressed after ACL injury in a cell type-specific manner. This study provides new insight into PTOA-associated changes in the immune microenvironment and highlights macrophage subtypes that may play a role in joint repair after injury.

Five-year Evaluation of Chronic Diseases in Hamadan, Iran: 2005-2009

BACKGROUND

Now the increasing growth of chronic diseases is the major health challenge worldwide. This survey was conducted to assess noncommunicable diseases related risk factors.

METHODS

A population-based cross sectional study was conducted in 2005 and repeated annually by 2009 in Hamadan province, the west of Iran using two-stage cluster sampling method. A total sample of 6500 subjects 15 to 64 years old were enrolled.

RESULTS

The total prevalence of cigarette smoking was 18% [95% CI 17% to 19%], 35.1% in men versus 1.1% in women. The smokers consumed on average 15 cigarettes per day. Almost 26.3% [95% CI 24.8% to 27.7%] of the target population eat five or more servings of fruits and vegetables per day; 52.8% [95% CI 51.2% to 54.3%] had work related physical activity; 28.1% [95% CI 26.7% to 29.4%] had physical activity during leisure time; 80.3% [95% CI 79.0% to 81.5%] had transportation related physical activity; 47.2% [95% CI 46.0% to 48.4%] were either overweight or obese; 8.1% [95% CI 7.1% to 9.2%] had impaired fasting blood sugar or were confirmed diabetes; 33.7% [95% CI 31.9% to 35.5%] had hypercholesterolemia; and 15.6% [95% CI 13.0% to 18.3%] had hypertriglyceridemia. There was a statistically significant association of age and gender with body mass index, systolic and diastolic hypertension, hyperglycemia, hypercholesterolemia and hypertriglyceridemia.

CONCLUSIONS

The evidences of the present survey promise a silent progressive epidemic of chronic diseases among Iranian citizens that may lead to an increasing growth of noncommunicable diseases in the next decade.

Effects of efrapeptin and destruxin, metabolites of entomogenous fungi, on the hydrolytic activity of a vacuolar type ATPase identified on the brush border membrane vesicles of Galleria mellonella midgut and on plant membrane bound hydrolytic enzymes

The brush border membrane of the insect midgut is an initial site for interaction of insecticidal proteins. We have investigated the possibility that it may contain a target site for two insecticidal fungal toxins, destruxin and efrapeptin, both of which are ATPase inhibitors. We have studied the effects of the toxins on the hydrolytic activity of a vacuolar type ATPase (V-ATPase) that we have identified from Galleria mellonella midgut columnar cell brush border membrane vesicles (BBMV) by its cation and pH dependence, sensitivity to proton pump inhibitors and K(m) (0.49 mM ATP). Efrapeptin strongly inhibited the BBMV V-ATPase but destruxin had little effect. We compared the effects of the inhibitors on known plant membrane hydrolytic enzymes, and although the vacuolar pyrophosphatase and plasma membrane ATPase were not inhibited by the toxins, the V-ATPase from mung bean, but not barley, was inhibited (50%) by 10 microM concentrations of both compounds. Different forms of the toxins were tested on the ATPases and destruxin B and efrapeptin F were the most effective. Kinetic analysis showed that the purified forms of both compounds inhibited the V-ATPases uncompetitively and modelling of data for inhibition of the BBMV V-ATPase by efrapeptin at concentrations of 0.06--12 microM yielded a K(i) of 0.125 microM.

Determination of the number of tuf genes in Chlamydia trachomatis and Neisseria gonorrhoeae

Restriction endonuclease fragments of DNA from Neisseria gonorrhoeae and Chlamydia trachomatis (mouse pneumonitis biovar) were hybridized to probes from the N-terminal and C-terminal portions of the Escherichia coli tufA gene. In common with other Gram-negative bacteria, the genome of N. gonorrhoeae was found to contain two homologous sequences (presumptive tuf genes). The C. trachomatis genome contained a single tuf sequence.

Inhibition of uptake of catecholamines by benzylamine derivatives

Eight benzylamine analogues of bretylium were synthesized, including N-(2-chloroethyl)-N-ethyl-2-methylbenzylamine (5), and evaluated as inhibitors of accumulation of norepinephrine and dopamine in rat brain homogenates. All compounds gave an I50 value (concentration of inhibitor that causes 50% reduction in control accumulation) considerably lower against norepinephrine in cortex that against dopamine in striatum. High potency (low I50) and high specificity (preference for inhibition of norepinephrine transport compared to dopamine transport) are associated with a (2-chloroethyl) moiety, tertiary amino center, and ortho substitution of the aromatic function in the benzylamino group. 5 also inhibited the uptake of norepinephrine in rabbit aorta, indicating its effect against the uptake process in general. Cocaine protects against the effects of 5 in coincubation studies when compared to the appropriate controls, indicating that 5 acts at or close to the site of action of cocaine which is thought to be the uptake carrier site.