Muscle-specific deletion of SOCS3 does not reduce the anabolic response to leucine in a mouse model of acute inflammation

Inflammation and Wasting of Skeletal Muscles in Kras-p53-Mutant Mice with Intraepithelial Neoplasia and Pancreatic Cancer-When Does Cachexia Start?

Skeletal muscle wasting critically impairs the survival and quality of life in patients with pancreatic ductal adenocarcinoma (PDAC). To identify the local factors initiating muscle wasting, we studied inflammation, fiber cross-sectional area (CSA), composition, amino acid metabolism and capillarization, as well as the integrity of neuromuscular junctions (NMJ, pre-/postsynaptic co-staining) and mitochondria (electron microscopy) in the hindlimb muscle of LSL-KrasG12D/+; LSL-TrP53R172H/+; Pdx1-Cre mice with intraepithelial-neoplasia (PanIN) 1-3 and PDAC, compared to wild-type mice (WT). Significant decreases in fiber CSA occurred with PDAC but not with PanIN 1-3, compared to WT: These were found in the gastrocnemius (type 2x: −20.0%) and soleus (type 2a: −21.0%, type 1: −14.2%) muscle with accentuation in the male soleus (type 2a: −24.8%, type 1: −17.4%) and female gastrocnemius muscle (−29.6%). Significantly higher densities of endomysial CD68+ and cyclooxygenase-2+ (COX2+) cells were detected in mice with PDAC, compared to WT mice. Surprisingly, CD68+ and COX2+ cell densities were also higher in mice with PanIN 1-3 in both muscles. Significant positive correlations existed between muscular and hepatic CD68+ or COX2+ cell densities. Moreover, in the gastrocnemius muscle, suppressor-of-cytokine-3 (SOCS3) expressions was upregulated >2.7-fold with PanIN 1A-3 and PDAC. The intracellular pools of proteinogenic amino acids and glutathione significantly increased with PanIN 1A-3 compared to WT. Capillarization, NMJ, and mitochondrial ultrastructure remained unchanged with PanIN or PDAC. In conclusion, the onset of fiber atrophy coincides with the manifestation of PDAC and high-grade local (and hepatic) inflammatory infiltration without compromised microcirculation, innervation or mitochondria. Surprisingly, muscular and hepatic inflammation, SOCS3 upregulation and (proteolytic) increases in free amino acids and glutathione were already detectable in mice with precancerous PanINs. Studies of initial local triggers and defense mechanisms regarding cachexia are warranted for targeted anti-inflammatory prevention.

The effect of lipoic acid on the content of SOD-1 and TNF-α in rat striated muscle

Background

The aim of the study was to present the effect of lipoic acid (LA) on oxidative stress induced by lipopolysaccharide (LPS).

Materials/Methods

The studies were conducted on male rats of the Wistar strain. The animals were divided into four groups. I: the controls received saline (0.2 ml); II: LPS, received LPS (Escherichia coli 026: B6) at a dose of 6 mg/kg body weight; III: LA, received LA at a dose of 60 mg/kg body weight; IV: LA + LPS, received LA (60 mg/kg b.w.) and after 30 min received LPS (6 mg/kg b.w.). All compounds were administered to the tail vein. After 5 hours of the experiment, the animals were anesthetized and striated muscle from the thigh was prepared. The isolated muscle was homogenized. Concentrations of superoxide dismutase-1 (SOD-1) and tumor necrosis factor alpha (TNF-α) were determined in the homogenates with the application of ELISA.

Results

The study showed a significant decrease in SOD-1 content and an increase in TNF-α in striated muscle after LPS administration. LA given 30 min before administration of LPS caused a significant increase in the level of SOD-1 and decreased levels of TNF-α in homogenates.

Conclusion

LA reduced the parameters of LPS oxidative stress, thus contributing to an increase in the body's antioxidant defense.

Iron accumulation in skeletal muscles of old mice is associated with impaired regeneration after ischaemia-reperfusion damage

BACKGROUND

Oxidative stress is implicated in the insidious loss of muscle mass and strength that occurs with age. However, few studies have investigated the role of iron, which is elevated during ageing, in age-related muscle wasting and blunted repair after injury. We hypothesized that iron accumulation leads to membrane lipid peroxidation, muscle wasting, increased susceptibility to injury, and impaired muscle regeneration.

METHODS

To examine the role of iron in age-related muscle atrophy, we compared the skeletal muscles of 3-month-old with 22- to 24-month-old 129SvEv FVBM mice. We assessed iron distribution and total elemental iron using laser ablation inductively coupled plasma mass spectrometry and Perls' stain on skeletal muscle cross-sections. In addition, old mice underwent ischaemia-reperfusion (IR) injury (90 min ischaemia), and muscle regeneration was assessed 14 days after injury. Immunoblotting was used to determine lipid peroxidation (4HNE) and iron-related proteins. To determine whether muscle iron content can be altered, old mice were treated with deferiprone (DFP) in the drinking water, and we assessed its effects on muscle regeneration after injury.

RESULTS

We observed a significant increase in total elemental iron (+43%, P < 0.05) and lipid peroxidation (4HNE: +76%, P < 0.05) in tibialis anterior muscles of old mice. Iron was further increased after injury (adult: +81%, old: +135%, P < 0.05) and associated with increased lipid peroxidation (+41%, P < 0.05). Administration of DFP did not impact iron or measures of lipid peroxidation in skeletal muscle or modulate muscle mass. Increased muscle iron concentration and lipid peroxidation were associated with less efficient regeneration, evident from the smaller fibres in cross-sections of tibialis anterior muscles (-24%, P < 0.05) and an increased percentage of fibres with centralized nuclei (+4124%, P < 0.05) in muscles of old compared with adult mice. Administration of DFP lowered iron after IR injury (PRE: -32%, P < 0.05 and POST: -41%, P < 0.05), but did not translate to structural improvements.

CONCLUSIONS

Muscles from old mice have increased iron levels, which are associated with increased lipid peroxidation, increased susceptibility to IR injury, and impaired muscle regeneration. Our results suggest that iron is involved in effective muscle regeneration, highlighting the importance of iron homeostasis in muscle atrophy and muscle repair.

Chimeric Peptidomimetics of SOCS 3 Able to Interact with JAK2 as Anti-inflammatory Compounds

The immunomodulatory effects of Suppressor of Cytokine Signaling (SOCS) proteins, that control the JAK/STAT pathway, indicate them as attractive candidates for immunotherapies. Recombinant SOCS3 protein suppresses the effects of inflammation, and its deletion in neurons or in immune cells increases pathological blood vessels growth. Recently, on the basis of the structure of the ternary complex among SOCS3, JAK2, and gp130, we focused on SOCS3 interfacing regions and designed several interfering peptides (IPs) that were able to mimic SOCS3 biological role in triple negative breast cancer (TNBC) models. Herein, to explore other protein regions involved in JAK2 recognition, several new chimeric peptides connecting noncontiguous SOCS3 regions and including a strongly aromatic fragment were investigated. Their ability to recognize the catalytic domain of JAK2 was evaluated through MST (microscale thermophoresis), and the most promising compound, named KIRCONG chim, exhibited a low micromolar value for dissociation constant. The conformational features of chimeric peptides were analyzed through circular dichroism and NMR spectroscopies, and their anti-inflammatory effects were assessed in cell cultures. Overall data suggest the importance of aromatic contribution in the recognition of JAK2 and that SOCS3 peptidomimetics could be endowed with a therapeutic potential in diseases with activated inflammatory cytokines.

[Role of cytokine signal suppressor 3 in the regulatory mechanism of colon cancer invasion and proliferation]

OBJECTIVE

To investigate the expression of cytokine signal suppressor 3 (SOCS3) in colon cancer tissue and the mechanism by which SOCS3 regulates the proliferation and invasion of colon cancer.

METHODS

We collected the specimens of tumor tissues and paired adjacent tissues from 80 patients with colon cancer undergoing radical resection in our hospital between July, 2014 and May, 2017, and the expression of SOCS3 in the tissue samples was analyzed using Western blotting. We also transfected colon cancer cell line SW480 with a SOCS3-overexpressing plasmid or a small interference RNA (siRNA) for SOCS3 knockdown, and the changes in the cell proliferation and invasion capacity were evaluated using CCK-8 assay and Transwell assay, respectively. The effect of demethylation and IL-6 treatment on SOCS3 expression and the proliferation and invasion of SW480 cells were observed.

RESULTS

Colon cancer tissues showed a lowered expression of SOCS3 compared with the adjacent tissues. Over-expression of SOCS3 significantly inhibited while SOCS3 knockdown obviously promoted the proliferation and invasion of SW480 cells in vitro. Demethylation treatment up-regulated SOCS3 expression and inhibited the proliferation and invasion capacity of SW480 cells; IL-6 treatment of the cells caused the reverse changes.

CONCLUSIONS

SOCS3 participates in the development and progression of colon cancer and serves as a potential target for colon cancer treatment. In patients with colon cancer, the low expression of SOCS3 possibly as a result of methylation may promote the proliferation and invasion of the cancer cells.

SOCS molecules: the growing players in macrophage polarization and function

The concept of macrophage polarization is defined in terms of macrophage phenotypic heterogeneity and functional diversity. Cytokines signals are thought to be required for the polarization of macrophage populations toward different phenotypes at different stages in development, homeostasis and disease. The suppressors of cytokine signaling family of proteins contribute to the magnitude and duration of cytokines signaling, which ultimately control the subtle adjustment of the balance between divergent macrophage phenotypes. This review highlights the specific roles and mechanisms of various cytokines family and their negative regulators link to the macrophage polarization programs. Eventually, breakthrough in the identification of these molecules will provide the novel therapeutic approaches for a host of diseases by targeting macrophage phenotypic shift.