The role of reactive oxygen species derived from different NADPH oxidase isoforms and mitochondria in oxalate-induced oxidative stress and cell injury

Research progress of AMP-activated protein kinase and cardiac aging

The process of aging is marked by a gradual deterioration in the physiological functions and functional reserves of various tissues and organs, leading to an increased susceptibility to diseases and even death. Aging manifests in a tissue- and organ-specific manner, and is characterized by varying rates and direct and indirect interactions among different tissues and organs. Cardiovascular disease (CVD) is the leading cause of death globally, with older adults (aged >70 years) accounting for approximately two-thirds of CVD-related deaths. The prevalence of CVD increases exponentially with an individual's age. Aging is a critical independent risk factor for the development of CVD. AMP-activated protein kinase (AMPK) activation exerts cardioprotective effects in the heart and restores cellular metabolic functions by modulating gene expression and regulating protein levels through its interaction with multiple target proteins. Additionally, AMPK enhances mitochondrial function and cellular energy status by facilitating the utilization of energy substrates. This review focuses on the role of AMPK in the process of cardiac aging and maintaining normal metabolic levels and redox homeostasis in the heart, particularly in the presence of oxidative stress and the invasion of inflammatory factors.

Oxalate (dys)Metabolism: Person-to-Person Variability, Kidney and Cardiometabolic Toxicity

Oxalate is a metabolic end-product whose systemic concentrations are highly variable among individuals. Genetic (primary hyperoxaluria) and non-genetic (e.g., diet, microbiota, renal and metabolic disease) reasons underlie elevated plasma concentrations and tissue accumulation of oxalate, which is toxic to the body. A classic example is the triad of primary hyperoxaluria, nephrolithiasis, and kidney injury. Lessons learned from this example suggest further investigation of other putative factors associated with oxalate dysmetabolism, namely the identification of precursors (glyoxylate, aromatic amino acids, glyoxal and vitamin C), the regulation of the endogenous pathways that produce oxalate, or the microbiota's contribution to oxalate systemic availability. The association between secondary nephrolithiasis and cardiovascular and metabolic diseases (hypertension, type 2 diabetes, and obesity) inspired the authors to perform this comprehensive review about oxalate dysmetabolism and its relation to cardiometabolic toxicity. This perspective may offer something substantial that helps advance understanding of effective management and draws attention to the novel class of treatments available in clinical practice.

Mitochondria-derived vesicles and their potential roles in kidney stone disease

Recent evidence has shown significant roles of mitochondria-derived vesicles (MDVs) in mitochondrial quality control (MQC) system. Under mild stress condition, MDVs are formed to carry the malfunctioned mitochondrial components, such as mitochondrial DNA (mtDNA), peptides, proteins and lipids, to be eliminated to restore normal mitochondrial structure and functions. Under severe oxidative stress condition, mitochondrial dynamics (fission/fusion) and mitophagy are predominantly activated to rescue mitochondrial structure and functions. Additionally, MDVs generation can be also triggered as the major MQC machinery to cope with unhealthy mitochondria when mitophagy is unsuccessful for eliminating the damaged mitochondria or mitochondrial fission/fusion fail to recover the mitochondrial structure and functions. This review summarizes the current knowledge on MDVs and discuss their roles in physiologic and pathophysiologic conditions. In addition, the potential clinical relevance of MDVs in therapeutics and diagnostics of kidney stone disease (KSD) are emphasized.

Renal tubular epithelial cells treated with calcium oxalate up-regulate S100A8 and S100A9 expression in M1-polarized macrophages via interleukin 6

Objectives

Calgranulins S100A8 and S100A9 are common in renal stones and they are up-regulated in both urinary exosomes and kidneys of stone patients. Renal sources and important regulators for S100A8 and S100A9 in nephrolithiasis were explored in this study.

Materials and Methods

We identified S100A8 and S100A9 abundance in various renal cells by searching the Single Cell Type Atlas. Macrophages were polarized from human myeloid leukemia mononuclear cells. Human proximal renal tubular epithelial cells (HK-2) were stimulated with calcium oxalate monohydrate (COM). Coculture experiments involving HK-2 cells and macrophages were conducted. qPCR, Western blotting, ELISA, and immunofluorescence were used for detecting interleukin 6 (IL6), S100A8, and S100A9.

Results

The Single Cell Type Atlas showed that S100A8 and S100A9 in human kidneys primarily originated from macrophages. M1 was the predominant macrophage type expressing S100A8 and S100A9. Direct culture with COM did not affect the expression of these two calgranulins in M1 macrophages but coculture with COM-treated HK-2 cells did. COM could promote HK-2 cells to secrete IL6. IL6 could up-regulate S100A8 and S100A9 expression in macrophages of M1 type. In addition, 0.5 μM SC144 (a kind of IL6 inhibitor) significantly prevented COM-treated HK-2 cells from up-regulating S100A8 and S100A9 expression in macrophages of M1 type.

Conclusion

M1-polarized macrophages were the predominant cell type expressing S100A8 and S100A9 in the kidneys of nephrolithiasis patients. CaOx crystals can promote renal tubular epithelial cells to secrete IL6 to up-regulate S100A8 and S100A9 expression in macrophages of M1 type.