OMA1 competitively binds to HSPA9 to promote mitophagy and activate the cGAS-STING pathway to mediate GBM immune escape

BACKGROUND

Immunotherapy with checkpoint inhibitors, especially those targeting programmed death receptor 1 (PD-1)/PD-1 ligand (PD-L1), is increasingly recognized as a highly promising therapeutic modality for malignancies. Nevertheless, the efficiency of immune checkpoint blockade therapy in treating glioblastoma (GBM) is constrained. Hence, it is imperative to expand our comprehension of the molecular mechanisms behind GBM immune escape (IE).

METHODS

Protein chip analysis was performed to screen aberrantly expressed OMA1 protein in PD-1 inhibitor sensitive or resistant GBM. Herein, public databases and bioinformatics analysis were employed to investigate the OMA1 and PD-L1 relation. Then, this predicted relation was verified in primary GBM cell lines through distinct experimental methods. To investigate the molecular mechanism behind OMA1 in immunosuppression, a series of experimental methods were employed, including Western blotting, co-immunoprecipitation (Co-IP), mass spectrometry (MS), immunofluorescence, immunohistochemistry, and qRT-PCR.

RESULTS

Our findings revealed that OMA1 competitively binds to HSPA9 to induce mitophagy and mediates the IE of GBM. Data from TCGA indicated a significant correlation between OMA1 and immunosuppression. OMA1 promoted PD-L1 levels in primary cells from patients with GBM. Next, the results of Co-IP and MS conducted on GBM primary cells revealed that OMA1 interacts with HSPA9 and induces mitophagy. OMA1 promoted not only cGAS-STING activity by increasing mitochondrial DNA release but also PD-L1 transcription by activating cGAS-STING. Eventually, OMA1 has been found to induce immune evasion in GBM through its regulation of PD-1 binding and PD-L1 mediated T cell cytotoxicity.

CONCLUSIONS

The OMA1/HSPA9/cGAS/PD-L1 axis is elucidated in our study as a newly identified immune therapeutic target in GBM.

Effect of local watershed landscapes on the nitrogen and phosphorus concentrations in the waterbodies of reservoir bays

Reservoir bays, which are affected by the reservoir and watershed characteristics, are the initial and most sensitive areas in the evolution process of reservoir water quality. However, the relationship between the watershed characteristics and nitrogen and phosphorus concentrations in reservoir bays is poorly understood. We selected 66 bays from the Danjiangkou Reservoir and sampled twice per year (storage and discharge periods) from 2015 to 2018 to monitor the total nitrogen (TN) and total phosphorus (TP) concentration in the waterbodies of the reservoir bays. Four types of watershed characteristic indices (topographic variables, soil variables, land-use composition, and landscape patterns) around these bays were obtained. We quantified the relationship between the TN and TP concentrations and watershed characteristics in the waterbodies of the reservoir bays using partial least squares regression (PLSR). The results showed that the mean concentrations of TN and TP in the storage period (TN:1.69 mg·L^-1, TP:0.088 mg·L^-1) were higher than those in the discharge period (TN:1.22 mg·L^-1, TP:0.063 mg·L^-1). The optimal PLSR models explained 67.9% and 82.5% of the TN concentration variability, and 65.4% and 67.2% of the TP concentration variability during the storage and discharge period, respectively. Based on the variable importance in the projection (VIP) values, soil erodibility had significant effects on the TN and TP concentrations. The key factors affecting the TN concentration were the slope gradient, basin relief, topographic wetness index, forest and agricultural land use, whereas the factors controlling the TP concentration were the landscape shape index, edge density, Shannon's diversity index and grass land use, although the TP concentration was also controlled by the patch density and contagion during the storage period, and by mean patch size and largest patch index during the discharge period. This study provides critical insights into sustainable landscape planning and effective reservoir water quality management.

Prevalence, characteristics and natural history of cold intolerance after the reverse digital artery flap

This retrospective study was designed to investigate the prevalence, characteristics and natural history of cold intolerance after the use of the reverse digital artery flap. A total of 123 patients were treated between 2010 and 2013. After excluding patients who were lost to follow-up, 87 patients were studied. The mean follow-up time was 34 months (range 14-61). Cold intolerance occurred in 60% (52) of patients after the reverse digital artery flap procedure. The condition improved in only 15% (8) of the patients. Significant differences were observed in the age and the specific digit involved between the groups with and without cold intolerance. There was a lower incidence in younger patients, and the ring finger group showed a lower incidence than in other fingers. Furthermore, the Cold Intolerance Symptom Severity score was positively correlated with the temperature at which cold intolerance was triggered.

LEVEL OF EVIDENCE

IV.

Comparative study of functional and aesthetically outcomes of reverse digital artery and reverse dorsal homodigital island flaps for fingertip repair

This retrospective study was designed to compare functional and cosmetic outcomes of the reverse digital artery island flap and reverse dorsal homodigital island flap in fingertip repair. A total of 23 patients were followed for 24 to 30 months. The reverse digital artery island flap was used in 12 patients, and reverse dorsal homodigital island flap in another 11 patients. Flap sensibility was assessed using the Semmes-Weinstein monofilament test and static 2-point discrimination test. Patient satisfaction, active motion of the finger joints, complications and cold intolerance were evaluated. The static 2-point discrimination and Michigan Hand Outcomes Questionnaire (appearance) of the fingers treated with a reverse digital artery flap were significantly better than those with a reverse dorsal homodigital flap. The static 2-point discrimination of the skin-grafted donor sides after dorsal homodigital flap were poorer than that in the contralateral finger. No significant differences were found between the two flaps for pressure or touch sensibility, active ranges of digital motion, complications and cold intolerance.

LEVEL OF EVIDENCE

III.

Bioglass-derived glass-ceramic scaffolds: study of cell proliferation and scaffold degradation in vitro

Cell support function as well as cell proliferation on highly porous Bioglass(R)-derived glass-ceramic scaffolds (designed for bone tissue engineering) have been assessed in vitro using osteoblast-like cells (MG 63) cultured for up to 6 days. The biodegradation and mechanical stability of the scaffolds in the cell-culture medium have also been investigated. It was found that the scaffolds had excellent cell supporting ability, with cells effectively infiltrating into and surviving at the center of the scaffolds. A quantitative study using the AlamarBlue assay revealed that the proliferation of cells on the glass-ceramic materials was comparable to that on the noncrystallized Bioglass. While the crystalline phase in the glass-ceramic scaffolds transformed into a biodegradable amorphous calcium phosphate phase during cell culture, the mechanical strength of the scaffolds was maintained when compared with that of scaffolds incubated in simulated body fluid or immersed in cell-free culture medium. It is believed that the attached cells and collagen secreted by cells could fill the micropores and microcracks on the surface of the foam struts, thus contributing to the mechanical stability of the degrading scaffolds. In summary, the developed glass-ceramic scaffolds possess the most essential features of a scaffold for bone tissue engineering: they are capable to support and foster relevant cells, able to provide temporary mechanical function, and biodegradable.

Myocardial tissue engineering: a review

Myocardial tissue engineering, a concept that intends to overcome the obstacles to prolonging patients' life after myocardial infarction, is continuously improving. It comprises a biomaterial based 'vehicle', either a porous scaffold or dense patch, made of either natural or synthetic polymeric materials, to aid transportation of cells into the diseased region in the heart. Many different cell types have been suggested for cell therapy and myocardial tissue engineering. These include both autologous and embryonic stem cells, both having their advantages and disadvantages. Biomaterials suggested for this specific tissue-engineering application need to be biocompatible with the cardiac cells and have particular mechanical properties matching those of native myocardium, so that the delivered donor cells integrate and remain intact in vivo. Although much research is being carried out, many questions still remain unanswered requiring further research efforts. In this review, we discuss the various approaches reported in the field of myocardial tissue engineering, focusing on the achievements of combining biomaterials and cells by various techniques to repair the infarcted region, also providing an insight on clinical trials and possible cell sources in cell therapy. Alternative suggestions to myocardial tissue engineering, in situ engineering and left ventricular devices are also discussed.

Vaterite deposition on biodegradable polymer foam scaffolds for inducing bone-like hydroxycarbonate apatite coatings

Hydroxycarbonate apatite (HCA) coatings on the surface of bioresorbable materials for bone tissue engineering scaffolds were produced using macroporous poly(DL-lactide) (PDLLA) foams impregnated by calcium carbonate in vaterite crystalline form. Stable and homogeneous vaterite deposition on PDLLA foams was achieved using a slurry dipping technique. In vitro studies in simulated body fluid (SBF) were performed to induce formation of (HCA) on the surface of vaterite/PDLLA composite foams. HCA was detected after immersion of foams in SBF for 7 days. Hence, depositing vaterite on materials followed by immersion in SBF is confirmed to induce HCA coatings on the surface of the material. The HCA coated, bioactive and resorbable PDLLA foams are intended for use as bone tissue engineering scaffolds.

Poly(D,L-lactic acid) coated 45S5 Bioglass-based scaffolds: processing and characterization

A comparative investigation has been carried out on the mechanical properties and bioactivity of Bioglass-based foams, before and after applying a poly(D,L-lactic acid) (PDLLA) coating layer on the foam struts. It was found that the bioactivity of foams upon immersion in simulated body fluid (SBF) was maintained in the PDLLA-coated foams; however, the transformation kinetics in SBF of the crystalline phase (Na(2)Ca(2)Si(3)O(9)) in the foam struts to an amorphous calcium phosphate phase was retarded by PDLLA coating. The compressive and three-point bending strengths of the Bioglass-based foams were slightly improved by the PDLLA-coating, and the work-of-fracture of the foams was considerably enhanced, as indicated by stress-strain curves. Immersion in SBF for 4 weeks led to a large decrease of the mechanical strength of as-sintered foams decreased (from 0.3 to 0.03 MPa), because of the transformation of the crystalline phase to an amorphous calcium phosphate. On the other hand, the mechanical strength was well-maintained in PDLLA-coated foams after immersion in SBF for 8 weeks. This behavior was attributed to the in-situ formation of a nanocomposite PDLLA/calcium phosphate film on the strut surfaces upon immersion in SBF.

The surface functionalization of 45S5 Bioglass-based glass-ceramic scaffolds and its impact on bioactivity

The first and foremost function of a tissue engineering scaffold is its role as a substrate for cell attachment, and their subsequent growth and proliferation. However, cells do not attach directly to the culture substrate; rather they bind to proteins that are adsorbed to the scaffold's surface. Like standard tissue culture plates, tissue engineering scaffolds can be chemically treated to couple proteins without losing the conformational functionality; a process called surface functionalization. In this work, novel highly porous 45S5 Bioglass-based scaffolds have been functionalized applying 3-AminoPropyl-TriethoxySilane (APTS) and glutaraldehyde (GA) without the use of organic solvents. The efficiency and stability of the surface modification was assessed by X-ray photoemission spectroscopy (XPS). The bioactivity of the functionalized scaffolds was investigated using simulated body fluid (SBF) and characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). It was found that the aqueous heat-treatment applied at 80 degrees C for 4 hrs during the surface functionalization procedure accelerated the structural transition of the crystalline Na2Ca2Si3O9 phase, present in the original scaffold structure as a result of the sintering process used for fabrication, to an amorphous phase during SBF immersion. The surface functionalized scaffolds exhibited an accelerated crystalline hydroxyapatite layer formation upon immersion in SBF caused by ion leaching and the increased surface roughness induced during the heat treatment step. The possible mechanisms behind this phenomenon are discussed.

Biodegradable and bioactive porous polymer/inorganic composite scaffolds for bone tissue engineering

Biodegradable polymers and bioactive ceramics are being combined in a variety of composite materials for tissue engineering scaffolds. Materials and fabrication routes for three-dimensional (3D) scaffolds with interconnected high porosities suitable for bone tissue engineering are reviewed. Different polymer and ceramic compositions applied and their impact on biodegradability and bioactivity of the scaffolds are discussed, including in vitro and in vivo assessments. The mechanical properties of today's available porous scaffolds are analyzed in detail, revealing insufficient elastic stiffness and compressive strength compared to human bone. Further challenges in scaffold fabrication for tissue engineering such as biomolecules incorporation, surface functionalization and 3D scaffold characterization are discussed, giving possible solution strategies. Stem cell incorporation into scaffolds as a future trend is addressed shortly, highlighting the immense potential for creating next-generation synthetic/living composite biomaterials that feature high adaptiveness to the biological environment.

Bioactive and mechanically strong Bioglass®-poly(D,L-lactic acid) composite coatings on surgical sutures

New coating processes have been investigated for degradable (Vicryl) and nondegradable (Mersilk) sutures with the aim to develop Bioglass coated polymer fibers for wound healing and tissue engineering scaffold applications. First, the aqueous phase of a Bioglass particle slurry was replaced with a poly(D,L-lactic acid) (PDLLA) polymer dissolved in solvent dimethyle carbonate (DMC) to act as third phase. SEM observations indicated that this alteration significantly improved the homogeneity of the coatings. Second, a new coating strategy involving two steps was developed: the sutures were first coated with a Bioglass-PDLLA composite film followed by a second PDLLA coating. This two-step process of coating has addressed the problem of poor adherence of Bioglass particles on suture surfaces. The coated sutures were knotted to determine qualitatively the mechanical integrity of the coatings. The results indicated that adhesion strength of coatings obtained by the two-step method was remarkably enhanced. A comparative assessment of the bioactivity of one-step and two-step produced coatings was carried out in vitro using acellular simulated body fluid (SBF) for up to 28 days. Coatings produced by the two-step process were found to have similar bioactivity as the one-step produced coatings. The novel Bioglass/PDLLA/Vicryl and Bioglass/PDLLA/Mersilk composite sutures are promising bioactive materials for wound healing and tissue engineering applications.

Strengthening mechanisms of bone bonding to crystalline hydroxyapatite in vivo

The formation and strengthening mechanisms of bone bonding of crystalline hydroxyapatite (HA) has been investigated using high-resolution transmission electron microscope (HRTEM) and energy-dispersive X-ray (EDX) analysis. A series of results were obtained: (i) a layer of amorphous HA, which has almost the same chemistry as the implanted HA, was formed on the surface of crystalline HA particles prior to dissolution; (ii) at 3 months a bone-like tissue formed a bonding zone between mature bone and the HA implant, composed of nanocrystalline and amorphous apatite; and (iii) at 6 months, mature bone was in direct contact with HA particles, and collagen fibres were perpendicularly inserted into the surface layer of implanted HA crystals. Findings (i) and (ii) indicated the following dissolution-precipitation process. (i) The crystalline HA transforms into amorphous HA; (ii) the amorphous HA dissolves into the surrounding solution, resulting in over-saturation; and (iii) the nanocrystallites are precipitated from the over-saturated solution in the presence of collagen fibres. A preliminary analysis indicated several conclusions: (i) the transition from crystalline to amorphous HA might be the controlling step in the bone bonding of crystalline HA; (ii) biological interdigitation (or incorporation) of collagen fibres with HA and chemical bonding of a apatite layer were both necessary to strengthen and toughen a bone bond, not only for the bonding between bone and HA at 6 months, but also for the bonding zone at 3 months, which would otherwise be very fragile due to the inherited brittleness of polycrystalline ceramics; and (iii) perpendicular interdigitation is an effective way for collagen fibres to impart their unique combination of flexibility and strength to the interface which they are keying.

Ultrastructural study of mineralization of a strontium-containing hydroxyapatite (Sr-HA) cementin vivo

The purpose of this study was to investigate the mineralization leading to osseointegration of strontium-containing hydroxyapatite (Sr-HA) bioactive bone cement injected into cancellous bone in vivo. Sr-HA cement was injected into the ilium of rabbits for 1, 3, and 6 months. The bone mineralization area was found to be largest at 3 months, then at 1 month, and smallest at 6 months (p < 0.01) measured with tetracycline labeling. Osseointegration of Sr-HA cement was achieved at 3 months as observed by scanning electron microscopy. A high calcium and phosphorus area was observed at the interface of bone-Sr-HA cement determined by energy-dispersive X-ray analysis. Transmission electron microscopy gave evidence of the mechanism of bone formation. Dissolution of Sr-HA into debris by the bone remodeling process was thought to increase the concentration of calcium and phosphorus at the interface of bone-Sr-HA cement and stimulate bone formation. Crystalline Sr-HA formed an amorphous layer and dissolved into the surrounding solution, then apatite crystallites were precipitated and formed new bone at 3 months. This young bone then becomes mature bone, which bonds tightly to the Sr-HA cement with collagen fibers inserted perpendicularly after 6 months.

[The changes in retinol-binding protein, N-acetyl-beta-glucosaminidase, albumin and IgG in urine before and after ESWL]

The retinol-binding protein (RBP), N-acetyl-beta-glucosaminidase, (NAG) albumin (alb) and IgG in urine were measured from 67 patients with urinary stone before and after ESWL. The results showed that the amount of alb, IgG and RBP in urine was obviously increased for the patients with renal, upper ureteral or lower ureteral stone associated with hydronephrosis. ESWL may injure the glomerule and tubules by direct or indirect action. 2 weeks after ESWL, the alb, IgG and RBP in urine returned to normal in 56.8%, 70.3% and 51.4% of cases respectively. Therefore we suggest that retreatment should be put off as late as 2 weeks after the first ESWL. However, it is not limited for retreatment of lower ureteral stones without hydro nephrosis.

[Diagnostic value of imaging in localizing primary aldosteronism]

From May 1985 to March 1993, 159 patients with primary aldosteronism were treated surgically. The results of localization of aldosteronomas by B-type ultrasonography, CT and scintigraphy in 103 were compared with pathological results. The accurate rate of the modalities was 80.6%, 75.8% and 67.4% respectively. As a routine, we usually employ sonography and CT for localizing aldosteronomas. Only when difficulty was encountered with these two methods, scintigraphy was added. In our series, an accurate rate of 96.1% was obtained in surgical explorations with these imaging examinations with a consideration of clinical data.