动物造模,局灶节段性肾小球硬化动物模型 z-bio 2021-12-30 807

　　Overview of the animal model of focal segmental glomerulosclerosis: FSGS causes asymptomatic proteinuria or nephrotic syndrome (NS) with or without renal insufficiency. Among adults undergoing renal biopsy to assess proteinuria, FSGS accounted for 35% of all cases. Generally speaking, FSGS is a progressive form of kidney disease, accounting for 2.3% of patients with end-stage renal disease (ESRD). Severe proteinuria at diagnosis is related to poor renal prognosis. FSGS summarizes the unique histological patterns of glomerular diseases, including sclerosis/fibrotic lesions under light microscope, which can only be found in some (focal) glomeruli and special parts of a single glomerulus (segment) Found in. The pathological mechanisms behind different forms of FSGS disease seem to be similar, resulting in the same histological picture. Therefore, it is reasonable and absolutely necessary to study the pathophysiological mechanism of FSGS in various animal models. Although humans and animals have different disease characteristics, animal models have become an important part of medical research. One of the most important differences is that many animal models reflect secondary FSGS, while primary FSGS is a more common form of human disease. Develop genetically engineered mice to improve our understanding of kidney diseases, including FSGS. The development of the main animal models of FSGS includes direct podocyte damage and indirect podocyte damage due to adaptive responses. Recent evidence indicates that podocyte depletion is a major factor in mediating proteinuria and glomerulosclerosis. The podocyte-specific toxin model supports that the loss of podocytes is sufficient to cause a dose-dependent FSGS. Gene knockout and transgenic models provide concepts that demonstrate that mutations in specific podocyte proteins mediate the hereditary form of FSGS. In this review, we describe the classic animal model FSGS and focus on new genetically engineered animal models.

　　The classic animal model of FSGS: Renal ablation model: One of the animal models for studying glomerular diseases is kidney ablation based on rats. The Brenner group showed that nephrectomy caused changes in glomerular blood flow, resulting in structural damage. It is suggested that persistent overfiltration of a single kidney may lead to the consequences of poor adaptation by destroying the residual glomeruli. The 5/6 nephrectomy model is produced by removing one kidney and ablating 2/3 of the remaining kidney. In this model, changes in glomerular structure due to severe renal mass reduction were detected as early as 2 weeks. At the seventh week, more than 50% of the glomeruli showed FSGS lesions, and all animals died within 90 days. Most rats are susceptible to glomerulosclerosis, while C57BL/6 mice are highly resistant to glomerulosclerosis. 129/SV and Swiss Webster mice are among the few mice that are susceptible to sclerosis. A 4/6 reduction in kidney mass resulted in a milder variation of FSGS without inducing hypertension. Imitating the secondary FSGS model, due to the loss of functional kidney tissue (trauma, tumor surgery, severe obesity, and very low birth weight infants), although the loss of nephron mass in animal models is more severe compared to human disease.

　　Experimental study of podocyte toxic drugs inducing FSGS: drugs that induce FSGS, especially toxic to podocytes, can induce FSGS in animals. The severity of FSGS is usually dose-dependent, the development of glomerular disease is reliable, and it is relatively easy to manage in these models. These models are suitable for studying protective and therapeutic effects or for studying the precise pathological mechanism of proteinuria nephropathy.

　　Aminonucleoside puromycin: Aminonucleoside puromycin (PAN) is an antibiotic that inhibits protein synthesis. Rats can induce PAN nephropathy in rats by a variety of induction programs, such as multiple intraperitoneal injections or single intravenous administration or without unilateral nephrectomy. Within a few days of a single administration of PAN (50 mg/kg body weight), large amounts of proteinuria appeared. The kidneys showed complete regression. The early stages of this model are similar to human minimal lesions. The stage of almost complete remission is stable, progressive, and low-level proteinuria, which develops between 10 and 13 weeks and is associated with early FSGS lesions. A follow-up of the animal model several months after PAN administration showed glomerulosclerosis and progressive renal failure. By the 18th week, about 10-15% of the glomeruli show segmental sclerosis. Use a single nephrectomy and multiple intraperitoneal injections (the first dose is 10 mg/kg body weight) to speed up the process. And clear glomerulosclerosis appeared in the 8th week.

　　Adriamycin model: Adriamycin is a known rat kidney injury toxicant, reflecting the histological changes observed in primary FSGS in human chronic kidney disease (CKD). For the first time, Sternberg et al. announced the use of anthracyclines to cause kidney damage. This animal model of kidney disease has several benefits. It is a highly reproducible and robust tissue damage model, with almost no death (<5%) and morbidity (weight loss). In male Wistar rats, the dose of doxorubicin required to induce kidney damage is between 1.5 and 7.5 mg/kg. Male BALB/c mice need 9.8 to 10.4 mg/kg of the drug, while male BALB/c SCID mice only need 5.3 mg/kg. C57BL/C mice have strong tolerance to adriamycin kidney injury. However, kidney damage can be induced by a higher dose (13-25 mg/kg) than that required in BALB/c mice. Although most studies use a single injection protocol, multiple injection protocols have also been reported. After 16 weeks, the FSGS phenotype was observed to progress to glomerulosclerosis and tubular interstitial fibrosis within 24 weeks. Due to elevated serum urea levels, some animals survive no more than 28 weeks. Similar to doxorubicin, the PAN model is directly toxic to podocytes, causing podocyte damage, increasing the permeability of endothelial cells, thereby reducing glomerular selectivity and secondary tubulointerstitial damage. The biggest disadvantage of these drug-induced models is their uncertainty with the human pathogenesis of FSGS.

　　Spontaneous FSGS model:

　　Buffalo/MWF model: Buffalo/MWF rat benign thymoma, proteinuria and nephrosclerosis occur spontaneously. The reason for the development of FSGS-like lesions is not clear. In addition to aging and hypertension, circulating nephrotoxic factors are also considered because of the recurrence of proteinuria after kidney transplantation in healthy Lewis rats.

　　Munich-Wistar-Fromter rat: The Munich Wistar Fromter (MWF) rat is a rat with a lower nephron count than the standard Wistar rat. Quantitative trait maps and whole-genome scans revealed sites on chromosome 6 associated with increased proteinuria. At 10 weeks of age, MWF rats developed proteinuria, with systolic blood pressure (SBP) ranging from 140 mm to 150 mm Hg. At 9 months, SBP reached 180 mmHg, and the kidneys showed obvious glomerular sclerosis. It is worth noting that these phenomena are more prominent in men than in women, despite similar nephron deficits. The single nephron glomerular filtration rate and glomerular volume of men higher than women may cause gender differences.

　　NEP25 mouse model: The NEP25 mouse model is a model specifically for podocytes. A transgenic mouse strain (NEP25) that selectively expresses human CD25 in podocytes has been produced. Anti-Tac (PV)-PE38 immunotoxin (lmb2) is an immunotoxin that specifically binds to human CD25. Induce progressive non-selective proteinuria, ascites and edema in NEP25 mice. Podocyte foot process disappearance, vacuole degeneration, shedding, synaptophysin, WT-1, Nefin and Podoalxin down-regulated. Mesangial cells of the glomerulus showed matrix expansion, increased collagen, vascular dissolution, and later hardening. Parietal epithelial cells show vacuolar degeneration and proliferation, and endothelial cells swell. The severity of glomerular injury is related to the dose-dependence of LBB2. With a dose of at least 1.25 ng/g body weight, NEP25 mice developed progressive glomerular damage and died within 2 weeks. At a dose of 0.625 ng/g body weight, NEP25 mice survived more than 4 weeks and developed focal segmental glomerulosclerosis.

　　Diphtheria toxin model: A transgenic rat line with human diphtheria toxin (DT) receptor specifically expressed in podocytes was established. Rodent homologues do not function as diphtheria toxin receptors, thus making rodents resistant to DT. Injection of DT (1ml/10g) into transgenic rats resulted in a dose-dependent depletion of glomerular podocytes. DT-induced podocyte loss leads to three stages of glomerular damage: 1, 0-20% stage, mesangial expansion, transient proteinuria, and normal renal function. Stage 2, 21 to 40%: Mesangial expansion, capsular adhesions (adhesion), focal segmental glomerulosclerosis, mild persistent proteinuria, normal renal function; stage 3, >40% podocyte reduction , Segmental glomerulosclerosis, persistent hyperproteinuria and decreased renal function. This model is also very suitable for research purposes due to its predictability.

　　HIV nephropathy model: HIV-associated nephropathy (HIVA) is one of the main causes of ESRD in the world. Therefore, it is important to understand the second form of FSG and the mechanisms related to its deterioration and improvement. To do this, an animal model of HIV-induced kidney disease is absolutely necessary. There are different virus-induced animal models in FSGS research. Most of them are based on HIV-1 models. Using replication-deficient HIV as an integrated transgene (called transgene 26) to establish an HIVA transgenic mouse model, proteinuria was first observed at 24 days of age. Approximately 20% of the mice died between 2 and 6 months, with elevated proteinuria, elevated blood urea nitrogen, edema, ascites, and hypoalbuminemia. Pathologically, the kidneys of uremic animals have collapsed lesions, diffuse segmental and systemic glomerular sclerosis, and microcapsule tubular expansion at a certain point in time. These changes are very similar to HIGHAN. HIVAN may develop due to direct infection of podocytes and local release of inflammatory cytokines.

　　New FSGS genetically engineered mouse model: Genetic engineering has revealed the possibility of studying the functions of many new genes and proteins in animal models. However, until now, mutations can only be identified in a small number of patients with FSGS. These animal models are essential for studying the function of individual proteins or protein-protein interactions and determining the prognosis of underlying diseases.

　　actin cytoskeleton

　　Α-actin 4 model: α-actin 4 is a cross-linked protein related to actin. Patients with mutations in the α-actin 4 gene are inherited in an autosomal dominant manner. The mutant protein causes the dynamic changes of the podocyte actin cytoskeleton and the degradation of the podocyte gap membrane, leading to proteinuria and early development of FSGS. Knockout mouse models have been established to study the effects of different human mutations. These studies help determine the purpose and physiological role of this cross-linked protein, as well as the consequences and severity of point mutations.

　　Top cell surface

　　Transient receptor potential channel 6 model: The latest development of familial FSGS is the discovery of a mutant form of mutant transient receptor potential cation channel 6 (TrPC6). This mutation leads to an increase in cell function and a transient increase in intracellular calcium concentration.

　　The relationship between hormone-resistant minimal change (MCD) and FSGS: We excluded animal models that only showed features of proteinuria or MCD without glomerulosclerosis. Several candidate circulating factors and their effects on podocytes have been proposed, but they are still insufficient to explain the overall mechanism and clinical features of MCD. Most patients are hormone resistant and often relapse quickly after transplantation. Currently 45 genes related to human NS explain no more than 20-30% of heredity. There are only 10 to 20% of sporadic cases. Therefore, we need a more detailed explanation of the pathological mechanism, including the combination of genetic and immunological studies of FSGS and steroid-resistant MCD.

　　Conclusion: Although the pathological mechanism of FSGS development is very complicated, classic and new genetic models have made significant progress in the past few decades. FSGS animal model explains the mechanism of many secondary chronic kidney disease complicated with proteinuria. These models provide a basis for further elucidating the methodologies for elucidating the pathophysiology of podocyte disease. Evidence obtained from these animal models and human observations determines the specific podocyte pathology of kidney disease.