Sequence Variation of Candida albicans Sap2 Enhances Fungal Pathogenicity via Complement Evasion and Macrophage M2-Like Phenotype Induction.

Candida albicans (C. albicans) is an opportunistic pathogen increasingly causing candidiasis worldwide. This study aims to investigate the pattern of systemic immune responses triggered by C. albicans with disease associated variation of Sap2, identifying the novel evasion strategies utilized by clinical isolates. Specifically, a variation in clinical isolates is identified at nucleotide position 817 (G to T). This homozygous variation causes the 273rd amino acid exchange from valine to leucine, close to the proteolytic activation center of Sap2. The mutant (Sap2-273L) generated from SC5314 (Sap2-273V) background carrying the V273L variation within Sap2 displays higher pathogenicity. In comparison to mice infected with Sap2-273V strain, mice infected with Sap2-273L exhibit less complement activation indicated by less serum C3a generation and weaker C3b deposition in the kidney. This inhibitory effect is mainly achieved by Sap2273L -mediated stronger degradation of C3 and C3b. Furthermore, mice infected with Sap2-273L strain exhibit more macrophage phenotype switching from M0 to M2-like and more TGF-ß release which further influences T cell responses, generating an immunosuppressed cellular microenvironment characterized by more Tregs and exhausted T cell formation. In summary, the disease-associated sequence variation of Sap2 enhances pathogenicity by complement evasion and M2-like phenotype switching, promoting a more efficient immunosuppressed microenvironment.

Glioma-derived LRIG3 interacts with NETO2 in tumor-associated macrophages to modulate microenvironment and suppress tumor growth.

Tumor-associated macrophages (TAMs) account for 30-50% of glioma microenvironment. The interaction between glioma tumor cells and TAMs can promote tumor progression, but the intrinsic mechanisms remain unclear. Herein, we reported that soluble LRIG3 (sLRIG3) derived from glioma tumor cells can block the M2 polarization of TAMs via interacting with NETO2, thus suppressing GBM malignant progression. The expression or activity of ADAM17 in glioma cells was positively correlated with the expression of sLRIG3 in cell supernatant. Soluble LRIG3 can suppress the M2-like polarity transformation of TAMs and inhibit the growth of tumor. High expression of LRIG3 predicts a good prognosis in patients with glioma. Mass spectrometry and Co-immunoprecipitation showed that sLRIG3 interacts with the CUB1 domain of NETO2 in TAMs. Silencing or knockout of NETO2 could block the effect of sLRIG3, which inhibited the M2-like polarity transformation of TAMs and promoted GBM tumor growth. However, overexpressing His-target NETO2 with CUB1 deletion mutation does not fully recover the suppressive effects of sLRIG3 on the TAM M2-polarization in NETO2-Knockout TAMs. Our study revealed vital molecular crosstalk between GBM tumor cells and TAMs. Glioma cells mediated the M2 polarization of TAM through the sLRIG3-NETO2 pathway and inhibited the progression of GBM, suggesting that sLRIG3-NETO2 may be a potential target for GBM treatment.

LRIG2 promotes glioblastoma progression by modulating innate antitumor immunity through macrophage infiltration and polarization.

BACKGROUND: Glioblastoma (GBM) is the most common malignant brain tumor with poor clinical outcomes. Immunotherapy has recently been an attractive and promising treatment of extracranial malignancies, however, most of clinical trials for GBM immunotherapy failed due to predominant accumulation of tumor-associated microglia/macrophages (TAMs). RESULTS: High level of LRIG2/soluble LRIG2 (sLRIG2) expression activates immune-related signaling pathways, which are associated with poor prognosis in GBM patients. LRIG2/sLRIGs promotes CD47 expression and facilitates TAM recruitment. Blockade of CD47-SIRPα interactions and inhibition of sLRIG2 secretion synergistically suppress GBM progression in an orthotropic murine GBM model. CONCLUSIONS: GBM cells with high level LRIG2 escape the phagocytosis by TAM via the CD47-SIRPα axis, highlighting a necessity for an early stage of clinical trial targeting LRIG2 and CD47-SIRPα as a novel treatment for patients with GBM.

The coupling of mitoproteolysis and oxidative phosphorylation enables tracking of an active mitochondrial state through MitoTimer fluorescence.

The regulation of mitochondria function and health is a central node in tissue maintenance, ageing as well as the pathogenesis of various diseases. However, the maintenance of an active mitochondrial functional state and its quality control mechanisms remain incompletely understood. By studying mice with a mitochondria-targeted reporter that shifts its fluorescence from "green" to "red" with time (MitoTimer), we found MitoTimer fluorescence spectrum was heavily dependent on the oxidative metabolic state in the skeletal muscle fibers. The mitoproteolytic activity was enhanced in an energy dependent manner, and accelerated the turnover of MitoTimer protein and respiratory chain substrate, responsible for a green predominant MitoTimer fluorescence spectrum under the oxidative conditions. PGC1α, as well as anti-ageing regents promoted enhanced mitoproteolysis. In addition, cells with the green predominant mitochondria exhibited lower levels of MitoSox and protein carbonylation, indicating a favorable redox state. Thus, we identified MitoTimer as a probe for mitoproteolytic activity in vivo and found a heightened control of mitoproteolysis in the oxidative metabolic state, providing a framework for understanding the maintenance of active oxidative metabolism while limiting oxidative damages.

Targeted Arginine Metabolism Therapy: A Dilemma in Glioma Treatment.

Efforts in the treatment of glioma which is the most common primary malignant tumor of the central nervous system, have not shown satisfactory results despite a comprehensive treatment model that combines various treatment methods, including immunotherapy. Cellular metabolism is a determinant of the viability and function of cancer cells as well as immune cells, and the interplay of immune regulation and metabolic reprogramming in tumors has become an active area of research in recent years. From the perspective of metabolism and immunity in the glioma microenvironment, we elaborated on arginine metabolic reprogramming in glioma cells, which leads to a decrease in arginine levels in the tumor microenvironment. Reduced arginine availability significantly inhibits the proliferation, activation, and function of T cells, thereby promoting the establishment of an immunosuppressive microenvironment. Therefore, replenishment of arginine levels to enhance the anti-tumor activity of T cells is a promising strategy for the treatment of glioma. However, due to the lack of expression of argininosuccinate synthase, gliomas are unable to synthesize arginine; thus, they are highly dependent on the availability of arginine in the extracellular environment. This metabolic weakness of glioma has been utilized by researchers to develop arginine deprivation therapy, which 'starves' tumor cells by consuming large amounts of arginine in circulation. Although it has shown good results, this treatment modality that targets arginine metabolism in glioma is controversial. Exploiting a suitable strategy that can not only enhance the antitumor immune response, but also "starve" tumor cells by regulating arginine metabolism to cure glioma will be promising.

Increased glycolysis in skeletal muscle coordinates with adipose tissue in systemic metabolic homeostasis.

Insulin-independent glucose metabolism, including anaerobic glycolysis that is promoted in resistance training, plays critical roles in glucose disposal and systemic metabolic regulation. However, the underlying mechanisms are not completely understood. In this study, through genetically manipulating the glycolytic process by overexpressing human glucose transporter 1 (GLUT1), hexokinase 2 (HK2) and 6-phosphofructo-2-kinase-fructose-2,6-biphosphatase 3 (PFKFB3) in mouse skeletal muscle, we examined the impact of enhanced glycolysis in metabolic homeostasis. Enhanced glycolysis in skeletal muscle promoted accelerated glucose disposal, a lean phenotype and a high metabolic rate in mice despite attenuated lipid metabolism in muscle, even under High-Fat diet (HFD). Further study revealed that the glucose metabolite sensor carbohydrate-response element-binding protein (ChREBP) was activated in the highly glycolytic muscle and stimulated the elevation of plasma fibroblast growth factor 21 (FGF21), possibly mediating enhanced lipid oxidation in adipose tissue and contributing to a systemic effect. PFKFB3 was critically involved in promoting the glucose-sensing mechanism in myocytes. Thus, a high level of glycolysis in skeletal muscle may be intrinsically coupled to distal lipid metabolism through intracellular glucose sensing. This study provides novel insights for the benefit of resistance training and for manipulating insulin-independent glucose metabolism.

Combinatory antitumor therapy by cascade targeting of a single drug.

Combination therapy has shown its promise in the clinic for enhancing the efficacy of tumor treatment. However, the dose control of multiple drugs and their non-overlapping toxicity from different drugs are still great challenge. In this work, a single model drug, paclitaxel (PTX), is used to realize combination therapy and solve the problems mentioned above. Either PTX or its triphenylphosphine derivative (TPTX) is encapsulated in galactose-modified liposomes (GLips) to obtain GLips-P or GLips-TP, which are simply mixed in different ratios to finely control the proportion of PTX and TPTX. These mixed liposomes, GLips-P/TP, feature a cascade target delivery of PTX, from tissue to cell, and then to organelle. PTX plays a primary role to cause the cytotoxicity by microtubule bindings in cytoplasm, while TPTX is proved to increase the intracellular levels of caspase-3 and caspase-9 that cause apoptosis via a mitochondria-mediated pathway. Notably, GLips-P/TP 3:1 exhibited the significant drug synergy in both cytotoxicity assay of HepG2 cells and the treatment efficacy in Heps xenograft ICR mouse models. This work not only demonstrates the great promise of a cascade targeting delivery for precise tumor treatment, but also offers a novel platform to design combinatory therapy systems using a single drug.

Mitochondria: promising organelle targets for cancer diagnosis and treatment.

Mitochondria, the energy supply factories for cell-life activities, play important roles in controlling epigenetics, differentiation and initiation, and the execution of apoptosis. These functions of the mitochondria contribute to cell adaptation to challenging microenvironment conditions. In past decades, mitochondrial malfunction has been revealed to be closely related to the occurrence and development of a variety of human disorders, including cancer and multiple neurodegenerative diseases. The disturbance of the mitochondrial genome (mtDNA) or mitochondrial vital functions, e.g., the production of adenosine triphosphate (ATP) and the generation of reactive oxygen species (ROS), can potentially be involved in disease pathogenesis. Recent research has shown that the precise monitoring of mitochondrial environments can provide potential directions for cancer diagnosis. Furthermore, mitochondrial-targeted cancer treatment exhibits unparalleled superiority for enhanced tumor therapy. Therefore, in this review, we focus on mitochondrial-based cancer diagnosis via monitoring mitochondrial respiration or mitophagy. Current approaches using mitochondrial-based cancer treatments, including targeting mitochondrial ATP, mitochondrial membrane permeability, and mitochondrial ROS levels and mtDNA, are also summarized. This review will provide insights into mitochondrial-mediated tumor monitoring and mitochondrial-based therapy.

p53 pathway is involved in cell competition during mouse embryogenesis.

The function of tumor suppressor p53 has been under intense investigation. Acute stresses such as DNA damage are able to trigger a high level of p53 activity, leading to cell cycle arrest or apoptosis. In contrast, the cellular response of mild p53 activity induced by low-level stress in vivo remains largely unexplored. Murine double minute (MDM)2 and MDM4 are two major negative regulators of p53. Here, we used the strategy of haploinsufficiency of Mdm2 and Mdm4 to induce mild p53 activation in vivo and found that Mdm2+/-Mdm4+/- double-heterozygous mice exhibited normal embryogenesis. However, closer examination demonstrated that the Mdm2+/-Mdm4+/- cells exhibited a growth disadvantage and were outcompeted during development in genetic mosaic embryos that contained wild-type cells. Further study indicated the out-competition phenotype was dependent on the levels of p53. These observations revealed that cells with mild p53 activation were less fit and exhibited altered fates in a heterotypic environment, resembling the cell competition phenomenon first uncovered in Drosophila By marking unfit cells for elimination, p53 may exert its physiological role to ensure organ and animal fitness.

Co-delivery of antineoplastic and protein drugs by chitosan nanocapsules for a collaborative tumor treatment.

Although combination delivery (co-delivery) shows much superiority in the defect compensation of single-agent therapy, the construction and application of co-delivery systems are still challenging, especially for protein-based joint systems. In this work, a series of chitosan (CS)-amino acid derivatives (Arg-CS, Lys-CS, and Phe-CS) with different degrees of substitution (DS) were synthesized to prepare CS nanocapsules (CNCs) using a simple emulsification method in the presence of linoleic acid (LA). The hydrophobic drug can be loaded in LA droplets, and a positively charged protein stabilized the optimized Arg-CS nanocapsules (Arg-CNCs) on their negative surfaces. The in vitro antitumor efficacy of Arg-CNCs co-delivering paclitaxel and recombinant human caspase-3 was evaluated in HeLa cells. The co-delivery system displayed much lower IC50 values and a higher percentage of apoptotic cells compared with the control groups. This system provides a promising and universal strategy for co-delivery, leading to collaborative tumor treatment.

Mouse Double Minute 2 Actively Suppresses p53 Activity in Oocytes during Mouse Folliculogenesis.

The p53 signaling network is indispensible in cellular stress responses and tumor suppression. Negative regulations of p53 by mouse double minute 2 (MDM2) and its homolog MDM4 are an integrated component of the network and have been implicated in regulating the stress responses and the maintenance of normal development and homeostasis of multiple somatic cell lineages. However, the regulatory role of MDM2 on p53 and stress responses in female germ cells remains undetermined. Here, we used the Cre-loxP system to delete Mdm2 in oocytes at different stages of folliculogenesis in mice. Mdm2 deletion resulted in a clear p53 nuclear accumulation in the oocytes and impeded fertilities with early follicular loss in mice, resembling human premature ovarian failure phenotypes. These phenotypes were fully rescued by concurrent deletion of p53 in mice. In addition, Nutlin-3, a small molecule compound that inhibited the binding of MDM2 to p53, also promoted p53-dependent oocyte death. Although cancer therapeutic agents 5-fluorouracil and doxorubicin could not induce a robust p53 activation in the wild-type oocytes, they induced p53 nuclear accumulation in the Mdm2 and Mdm4 double heterozygous oocytes. These results demonstrated a critical prosurvival role for MDM2 in the oocytes. Moreover, they suggested a more tightened and rigorous regulatory mode for the MDM2/MDM4-p53 network in female germ cells under stress situations.

Irisin improves perivascular adipose tissue dysfunction via regulation of the heme oxygenase-1/adiponectin axis in diet-induced obese mice.

AIMS: To determine whether irisin could improve perivascular adipose tissue (PVAT) dysfunction via regulation of the heme oxygenase-1 (HO-1)/adiponectin axis in obesity. MATERIALS AND METHODS: C57BL/6 mice were given chow or a high-fat diet (HFD) with or without treatment with irisin. The concentration-dependent responses of the thoracic aorta with or without PVAT (PVAT+ or PVAT-) to phenylephrine were studied in an organ bath. Protein levels of HO-1 and adiponectin were determined by western blot. UCP-1, Cidea, and TNF-α gene expression in PVAT were analyzed by real-time PCR. RESULTS: Treatment of obese mice with irisin improved glucose and lipid metabolism, reduced plasma levels of TNF-α and malondialdehyde, and increased plasma adiponectin levels (P<0.01). The anti-contractile effects of PVAT were attenuated in HFD mice and this attenuation was restored in HFD mice treated with irisin (P<0.05). Incubation of aortas (PVAT+) with the HO-1 inhibitor and adiponectin receptor blocking peptide in irisin-treated HFD mice abolished the beneficial effects of irisin on PVAT function. The same results were also observed in HFD mice treated with irisin ex vivo. Treatment of HFD mice with irisin significantly enhanced protein levels of HO-1 and adiponectin, and reduced superoxide production and TNF-α expression in PVAT. Irisin treatment enhanced brown adipocyte markers UCP-1 and Cidea expression in PVAT from HFD mice. CONCLUSION: Irisin improved the anti-contractile properties of PVAT from the thoracic aorta in diet-induced obese mice. The mechanism for protective effects of irisin appeared to be related to upregulation of the HO-1/adiponectin axis in PVAT and browning of PVAT.