Bacterial lipoteichoic acid induces capsular contracture by activating innate immune response.

BACKGROUND: Capsular contracture is attributed to an exaggerated fibrosis response within the capsule and is partly associated with bacterial contamination in situ. However, the cellular mechanisms that initiate this response are unclear. METHODS: We developed a mouse model of capsular contracture by repeated injection of 10 µg/ml lipoteichoic acid (LTA). The histological changes in the capsule tissue were measured by hematoxylin-eosin, Masson, and immunohistochemical staining. The expression of cytokines was measured by quantitative reverse-transcription polymerase chain reaction. We also used pharmacological methods to verify the roles of macrophages and Toll-like receptor 2 (TLR2) signaling in this pathological process. RESULTS: We discovered that repeated LTA injection, at a low concentration, could induce the thickening of the capsule tissue. Macrophage infiltration and TLR2/nuclear factor-kappa B (NF-κB) signaling activated in this process could be suppressed by macrophage depletion or TLR2 receptor inhibition. CONCLUSIONS: As TLR2 signal activation was found to cause capsular contracture by inducing macrophage infiltration as a consequence of trace amounts of LTA contamination in situ, this target is helpful for understanding that chronic or repeated subclinical infection could activate capsular contracture.

Repeated Lipoteichoic Acid Injection at Low Concentration Induces Capsular Contracture by Activating Adaptive Immune Response through the IL-6/STAT3 Signaling Pathway.

BACKGROUND: Capsular contracture is the most common complication of breast implantation surgery. Bacterial contamination was considered to play an important role in the occurrence of capsular contracture, and Gram-positive bacteria such as Staphylococcus epidermidis were discovered in the clinical specimens. Lipoteichoic acid (LTA) was a component of the cell wall of Gram-positive bacteria and was sufficient in the pathogenicity of the bacteria. The authors assumed that LTA could trigger the immunologic response against the implant and cause capsular contracture. METHODS: The authors developed a rat model of capsular contracture by repeated injection of 10 µg/mL LTA. The histologic changes of the capsule tissue were measured by hematoxylin and eosin, sirius red, Masson, and immunohistochemical staining. The expression of related cytokines was measured by quantitative real-time polymerase chain reaction. The downstream pathway activation was shown by Western blot. The authors also applied tocilizumab, an interleukin (IL)-6 receptor antagonist, to verify the role of IL-6 in this pathologic process. RESULTS: The authors discovered that repeated LTA injection, at a low concentration, could induce the thickening of capsule tissue, the deposition of collagen fiber, and the activation of myofibroblasts. The IL-6/signal transducer and activator of transcription 3 signaling pathway was activated in this process, and the inhibition of IL-6 receptor could relieve the symptoms. B cells and T-helper cells, especially T-helper type 1, could be related to this phenomenon. CONCLUSIONS: The authors' research corroborated that subclinical infection could trigger capsular contracture, and the immune system played an important role in this process. The authors' results provided a possible research direction for the mechanism of bacterial infection-induced immune response against breast implants. CLINICAL RELEVANCE STATEMENT: The authors' research provides a possible research direction for the mechanism of bacterial infection-induced immune response against breast implants, and a potential target for predicting the prognosis of capsular contracture.

Prognostic genes of melanoma identified by weighted gene co-expression network analysis and drug repositioning using a network-based method.

Melanoma is one of the most malignant types of skin cancer. However, the efficacy and utility of available drug therapies for melanoma are limited. The objective of the present study was to identify potential genes associated with melanoma progression and to explore approved therapeutic drugs that target these genes. Weighted gene co-expression network analysis was used to construct a gene co-expression network, explore the associations between genes and clinical characteristics and identify potential biomarkers. Gene expression profiles of the GSE65904 dataset were obtained from the Gene Expression Omnibus database. RNA-sequencing data and clinical information associated with melanoma obtained from The Cancer Genome Atlas were used for biomarker validation. A total of 15 modules were identified through average linkage hierarchical clustering. In the two significant modules, three network hub genes associated with melanoma prognosis were identified: C-X-C motif chemokine receptor 4 (CXCR4), interleukin 7 receptor (IL7R) and phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit γ (PIK3CG). The receiver operating characteristic curve indicated that the mRNA levels of these genes exhibited excellent prognostic efficiency for primary and metastatic tumor tissues. In addition, the proximity between candidate genes associated with melanoma progression and drug targets obtained from DrugBank was calculated in the protein interaction network, and the top 15 drugs that may be suitable for treating melanoma were identified. In summary, co-expression network analysis led to the selection of CXCR4, IL7R and PIK3CG for further basic and clinical research on melanoma. Utilizing a network-based method, 15 drugs that exhibited potential for the treatment of melanoma were identified.

TRIM44 activates the AKT/mTOR signal pathway to induce melanoma progression by stabilizing TLR4.

BACKGROUND: There is growing evidence that tripartite motif-containing protein 44 (TRIM44) plays crucial role in tumor development. However, the underlying mechanism of this deubiquitinating enzyme remains unclear. METHODS: Large clinical samples were used to detect TRIM44 expression and its associations with clinicopathological features and prognosis. Gain- and loss-of-function experiments in cell lines and mouse xenograft models were performed to elucidate the function and underlying mechanisms of TRIM44 induced tumor progression. Co-immunoprecipitation (Co-IP) assays and mass spectrometric analyses were applied to verify the interacting proteins of TRIM44. RESULTS: We found that TRIM44 was commonly amplified in melanoma tissues compared with paratumoral tissues. TRIM44 expression also positively correlated with more aggressive clinicopathological features, such as Breslow depth (p = 0.025), distant metastasis (p = 0.012), and TNM stage (p = 0.002). Importantly, we found that TRIM44 was an independent indicator of prognosis for melanoma patients. Functionally, overexpression of TRIM44 facilitated cell invasion, migration, apoptosis resistance and proliferation in vitro, and promoted lung metastasis and tumorigenic ability in vivo. Importantly, high level of TRIM44 induced melanoma cell epithelial-mesenchymal transition (EMT), which is one of the most important mechanisms for the promotion of tumor metastasis. Mechanistically, high levels of TRIM44 increased the levels of p-AKT (T308) and p-mTOR (S2448), and a specific AKT inhibitor inhibited TRIM44-induced tumor progression. Co-IP assays and mass spectrometric analyses indicated that TRIM44 overexpression induces cell EMT through activating AKT/mTOR pathway via directly binding and stabilizing TOLL-like receptor 4 (TLR4), and TLR4 interference impeded TRIM44 induced tumor progression. Moreover, we demonstrated that TRIM44 is the target of miR-26b-5p, which is significantly downregulated in melanoma tissues and may be responsible for the overexpression of TRIM44. CONCLUSIONS: TRIM44, regulated by miR-26b-5p, promotes melanoma progression by stabilizing TLR4, which then activates the AKT/mTOR pathway. TRIM44 shows promise as a prognostic predictor and a therapeutic target for melanoma patients.