Skeletal muscle inflammation and atrophy in heart failure.

Heart failure represents a systemic disease with profound effects on multiple peripheral tissues including skeletal muscle. Within the context of heart failure, perturbations in skeletal muscle physiology, structure, and function strongly contribute to exercise intolerance and the morbidity of this devastating disease. There is growing evidence that chronic heart failure imparts specific pathological changes within skeletal muscle beds resulting in muscle dysfunction and tissue atrophy. Mechanistically, systemic and local inflammatory responses drive critical aspects of this pathology. In this review, we will discuss pathological mechanisms that drive skeletal muscle inflammation and highlight emerging roles for distinct innate immune subsets that reside within damage muscle tissue focusing on the recently described embryonic and monocyte-derived macrophage lineages. Within this context, we will discuss how immune mechanisms can be differentially targeted to stimulate skeletal muscle inflammation, catabolism, fiber atrophy, and regeneration.

Vitamin D Levels Are Unrelated to the Severity of Respiratory Syncytial Virus Bronchiolitis Among Hospitalized Infants.

BACKGROUND: Vitamin D deficiency at birth has been reported as a risk factor for respiratory syncytial virus (RSV) lower respiratory tract infection during the first year of life. Limited data are available on whether an infant's vitamin D status is associated with the severity of acute RSV bronchiolitis. METHODS: Infants < 1 year of age and hospitalized with their first episode of RSV bronchiolitis were enrolled into the RSV Bronchiolitis in Early Life II cohort. We investigated the relationships between vitamin D status at enrollment and the following indicators of bronchiolitis severity: duration of hospitalization, lowest oxygen saturation measured during hospitalization, and bronchiolitis severity score. RESULTS: Among the 145 enrolled infants, the median (quartile 1 [Q1], Q3) serum 25-OH-VitD level was 36.8 (29.8, 42.3) ng/mL, with 14 infants (9.7%) having deficient serum vitamin D levels (25-OH-VitD <20 ng/mL). Vitamin D-deficient infants were younger than infants with 25-OH-VitD ≥ 20 ng/mL (2.8 vs 4.5 months, respectively; P = .04) and were less likely to consume infant's formula (42.9% vs 87.0%, respectively; P < .01). The following indicators of acute bronchiolitis severity did not differ between infants who were vitamin D-deficient and nondeficient: duration of hospitalization (P = .53), lowest oxygen saturation (P = .45), and bronchiolitis severity score (P = .97), even after adjusting for age, and for infant's formula consumption. CONCLUSIONS: Among this cohort of infants that were hospitalized for RSV bronchiolitis, vitamin D status at the time of bronchiolitis was not associated with indicators of acute bronchiolitis severity.

Deletion of macrophage Vitamin D receptor promotes insulin resistance and monocyte cholesterol transport to accelerate atherosclerosis in mice.

Intense effort has been devoted to understanding predisposition to chronic systemic inflammation because it contributes to cardiometabolic disease. We demonstrate that deletion of the macrophage vitamin D receptor (VDR) in mice (KODMAC) is sufficient to induce insulin resistance by promoting M2 macrophage accumulation in the liver as well as increasing cytokine secretion and hepatic glucose production. Moreover, VDR deletion increases atherosclerosis by enabling lipid-laden M2 monocytes to adhere, migrate, and carry cholesterol into the atherosclerotic plaque and by increasing macrophage cholesterol uptake and esterification. Increased foam cell formation results from lack of VDR-SERCA2b interaction, causing SERCA dysfunction, activation of ER stress-CaMKII-JNKp-PPARγ signaling, and induction of the scavenger receptors CD36 and SR-A1. Bone marrow transplant of VDR-expressing cells into KODMAC mice improved insulin sensitivity, suppressed atherosclerosis, and decreased foam cell formation. The immunomodulatory effects of vitamin D in macrophages are thus critical in diet-induced insulin resistance and atherosclerosis in mice.

Vascular calcification and aortic fibrosis: a bifunctional role for osteopontin in diabetic arteriosclerosis.

OBJECTIVE: Calcification and fibrosis reduce vascular compliance in arteriosclerosis. To better understand the role of osteopontin (OPN), a multifunctional protein upregulated in diabetic arteries, we evaluated contributions of OPN in male low-density lipoprotein receptor (LDLR)-/- mice fed a high-fat diet. METHODS AND RESULTS: OPN had no impact on high-fat diet-induced hyperglycemia, dyslipidemia, or body composition. However, OPN-/-;LDLR-/- mice exhibited an altered time-course of aortic calcium accrual-reduced during initiation but increased with progression-versus OPN+/+;LDLR-/- controls. Collagen accumulation, chondroid metaplasia, and mural thickness were increased in aortas of OPN-/-;LDLR-/- mice. Aortic compliance was concomitantly reduced. Vascular reexpression of OPN (SM22-OPN transgene) reduced aortic Col2A1 and medial chondroid metaplasia but did not affect atherosclerotic calcification, Col1A1 expression, collagen accumulation, or arterial stiffness. Dosing with the proinflammatory OPN fragment SVVYGLR upregulated aortic Wnt and osteogenic gene expression, increased aortic ß-catenin, and restored early-phase aortic calcification in OPN-/-;LDLR-/- mice. CONCLUSIONS: OPN exerts stage-specific roles in arteriosclerosis in LDLR-/- mice. Actions phenocopied by the OPN metabolite SVVYGLR promote osteogenic calcification processes with disease initiation. OPN limits vascular chondroid metaplasia, endochondral mineralization, and collagen accumulation with progression. Complete deficiency yields a net increase in arteriosclerotic disease, reducing aortic compliance and conduit vessel function in LDLR-/- mice.

Runx2 trans-activation mediated by the MSX2-interacting nuclear target requires homeodomain interacting protein kinase-3.

Runt-related transcription factor 2 (Runx2) and muscle segment homeobox homolog 2-interacting nuclear target (MINT) (Spen homolog) are transcriptional regulators critical for mammalian development. MINT enhances Runx2 activation of osteocalcin (OC) fibroblast growth factor (FGF) response element in an FGF2-dependent fashion in C3H10T1/2 cells. Although the MINT N-terminal RNA recognition motif domain contributes, the muscle segment homeobox homolog 2-interacting domain is sufficient for Runx2 activation. Intriguingly, Runx1 cannot replace Runx2 in this assay. To better understand this Runx2 signaling cascade, we performed structure-function analysis of the Runx2-MINT trans-activation relationship. Systematic truncation and domain swapping in Runx1:Runx2 chimeras identified that the unique Runx2 activation domain 3 (AD3), encompassed by residues 316-421, conveys MINT+FGF2 trans-activation in transfection assays. Ala mutagenesis of Runx2 Ser/Thr residues identified that S301 and T326 in AD3 are necessary for full MINT+FGF2 trans-activation. Conversely, phosphomimetic Asp substitution of these AD3 Ser/Thr residues enhanced activation by MINT. Adjacent Pro residues implicated regulation by a proline-directed protein kinase (PDPK). Systematic screening with PDPK inhibitors identified that the casein kinase-2/homeodomain-interacting protein kinase (HIPK)/dual specificity tyrosine phosphorylation regulated kinase inhibitor 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole (DMAT), but not ERK, c-Jun N-terminal kinase, p38MAPK, or other casein kinase-2 inhibitors, abrogated Runx2-, MINT-, and FGF2-activation. Systematic small interfering RNA-mediated silencing of DMAT-inhibited PDPKs revealed that HIPK3 depletion reduced MINT+FGF2-dependent activation of Runx2. HIPK3 and Runx2 coprecipitate after in vitro transcription-translation, and recombinant HIPK3 recognizes Runx2 AD3 as kinase substrate. Furthermore, DMAT treatment and HIPK3 RNAi inhibited MINT+FGF2 activation of Runx2 AD3, and nuclear HIPK3 colocalized with MINT. HIPK3 antisense oligodeoxynucleotide selectively reduced Runx2 protein accumulation and OC gene expression in C3H10T1/2 cells. Thus, HIPK3 participates in MINT+FGF2 regulation of Runx2 AD3 activity and controls Runx2-dependent OC expression.

Msx2 exerts bone anabolism via canonical Wnt signaling.

Msx2 is a homeodomain transcription factor first identified in craniofacial bone and human femoral osteoblasts. We hypothesized that Msx2 might activate skeletal Wnt signaling. Therefore, we analyzed the effects of CMV-Msx2 transgene (Msx2Tg) expression on skeletal physiology and composition. Skeletal Msx2 expression was increased 2-3-fold by Msx2Tg, with expanded protein accumulation in marrow, secondary ossification centers, and periosteum. Microcomputed tomography established increased bone volume in Msx2Tg mice, with increased numbers of plate-like trabeculae. Histomorphometry revealed increased bone formation in Msx2Tg mice versus non-Tg siblings, arising from increased osteoblast numbers. While decreasing adipogenesis, Msx2Tg increased osteogenic differentiation via mechanisms inhibited by Dkk1, an antagonist of Wnt receptors LRP5 and LRP6. Bone from Msx2Tg mice elaborated higher levels of Wnt7 canonical agonists, with diminished Dkk1, changes that augment canonical signaling. Analysis of non-Tg and Msx2Tg siblings possessing the TOPGAL reporter confirmed this; Msx2Tg up-regulated skeletal beta-galactosidase expression (p

MINT, the Msx2 interacting nuclear matrix target, enhances Runx2-dependent activation of the osteocalcin fibroblast growth factor response element.

Msx2 promotes osteogenic lineage allocation from mesenchymal progenitors but inhibits terminal differentiation demarcated by osteocalcin (OC) gene expression. Msx2 inhibits OC expression by targeting the fibroblast growth factor responsive element (OCFRE), a 42-bp DNA domain in the OC gene bound by the Msx2 interacting nuclear target protein (MINT) and Runx2/Cbfa1. To better understand Msx2 regulation of the OCFRE, we have studied functional interactions between MINT and Runx2, a master regulator of osteoblast differentiation. In MC3T3E1 osteoblasts (with endogenous Runx2 and FGFR2), MINT augments transcription driven by the OCFRE that is further enhanced by FGF2 treatment. OCFRE regulation can be reconstituted in the naïve CV1 fibroblast cell background. In CV1 cells, MINT synergizes with Runx2 to enhance OCFRE activity in the presence of activated FGFR2. The RNA recognition motif domain of MINT (which binds the OCFRE) is required. Runx2 structural studies reveal that synergy with MINT uniquely requires Runx2 activation domain 3. In confocal immunofluorescence microscopy, MINT adopts a reticular nuclear matrix distribution that overlaps transcriptionally active osteoblast chromatin, extensively co-localizing with the phosphorylated RNA polymerase II meshwork. MINT only partially co-localizes with Runx2; however, co-localization is enhanced 2.5-fold by FGF2 stimulation. Msx2 abrogates Runx2-MINT OCFRE activation, and MINT-directed RNA interference reduces endogenous OC expression. In chromatin immunoprecipitation assays, Msx2 selectively inhibits Runx2 binding to OC chromatin. Thus, MINT enhances Runx2 activation of multiprotein complexes assembled by the OCFRE. Msx2 targets this complex as a mechanism of transcriptional inhibition. In osteoblasts, MINT may serve as a nuclear matrix platform that organizes and integrates osteogenic transcriptional responses.

Mayor frecuencia de giardiosis en niños con raquitismo comparada con niños sanos de la población de Suárez, Cauca, Colombia / Greater giardiasis frequency amongst children with rickets compared to healthy children from the town of Suárez, Cauca, Colombia

Se examinaron huevos, quistes y trofozoítos de parásitos intestinales en heces de 332 niños sanos y 70 niños con raquitismo descrito como un trastorno heredado debido a malabsorción de calcio por resistencia a la vitamina D en Suárez, departamento del Cauca. La frecuencia total de parasitosis fue de 65,9 por ciento y la de poliparasitismo de 10,9 por ciento. Se encontraron frecuencias elevadas de giardiosis y poliparasitismo en niños con raquitismo (17,1 y 18,6 por ciento) comparado con niños sanos (9,0 y 9,3 por ciento) y dichas diferencias fueron estadísticamente significativas. La vereda de La Toma, en donde se ha hallado el mayor número de raquíticos, pareció conferir un riesgo incrementado para ascariosis, pero, independiente del raquitismo. Se discuten algunos mecanismos para explicar la mayor frecuencia de parasitosis en niños raquíticos. La incremenda frecuencia de parasitosis intestinales patógenas puede contribuir a disminuir la absorción intestinal de calcio en los niños raquíticos