Identification of ferroptosis-related molecular markers in glomeruli and tubulointerstitium of lupus nephritis.

PURPOSE: Ferroptosis, characterized by iron accumulation and lipid peroxidation, is a newly demonstrated form of programed cell death. Present studies reveal that ferroptosis is involved in tumor and neurodegenerative disease. Regarding its roles in the development of LN, it is least interrogated. In this study, we explored whether ferroptosis is activated and how does it change at transcriptomic level in LN. METHODS: 4-Hydroxynonenal (4-HNE) was stained to explore whether ferroptosis is activated. Subsequently, by using bioinformatic methods, public GSE32591 dataset was analyzed. Ferroptosis-related differentially expressed genes (FR-DEGs) were identified in both glomeruli and tubulointerstitium. Immune cell infiltration was evaluated. Correlation between FR-DEGs and infiltrated immune cells was also calculated. Finally, dataset of GSE113342, qPCR, and immunofluorescence staining were also used or performed to validate the results. RESULTS: Expression of 4-HNE was significantly increased in both glomeruli and tubulointerstitium. At transcriptomic level, 19 FR-DEGs in glomeruli and 15 FR-DEGs in tubulointerstitium including genes of iron metabolism, antioxidant system inhibitors, and ferroptosis suppressors were significantly altered in LN. Of which, LTF, CYBB, and CCL5 were upregulated and G0S2 and AKR1C1 were downregulated in both glomeruli and tubulointerstitium of LN. qPCR further validated the alteration of LTF, CYBB, CCL5, G0S2, and AKR1C1 in the whole kidney. Correlation analysis showed that CYBB positively correlated with monocyte infiltration in glomeruli and positively correlated with response to therapy. CONCLUSION: Lipid peroxidation was aberrantly activated in LN, suggesting the activation of ferroptosis. LTF, CYBB, CCL5, G0S2, and AKR1C1, especially CYBB, might be good biomarkers of ferroptosis in LN.

A new algorithm for evaluating reservoir density based on X-ray logging technology.

Rock density is an important parameter to provide critical information for evaluating both conventional and unconventional reservoirs. During the drilling process, it's a huge challenge to eliminating the negative effects of irregular mud cake formed in drilling fluid deposition to evaluating reservoir information accurately. However, the calibration of density measurement by correction charts would usually generate large errors, and the parameters that need to be corrected are often unpredictable. Therefore, based on the X-ray density logging technology, while eliminating the radioactive hazards of the isotope gamma source (137Cs), a new method is proposed to address the problem through the energy spectrum information from four detectors. Theoretically, this method would analyze the role of X-rays in the dual media of formation and mud cake and then integrate the energy spectrum information from four detectors, while using Newton iterative inversion to invert the parameters about formation and mud cake. As a result, the evaluation of reservoir parameters can be achieved without correcting the mud cake. In verifying the effectiveness of this method, a simulation example shows the high accuracy of X-ray density inversion for multiple parameters. This research provides an X-ray density inversion algorithm to realize the simultaneous calculation of formation and mud cake parameters, which is of great significance for guiding hydrocarbon exploration and production.