Therapeutic agents for renal diseases and method for screening the same

Abstract

The present invention provides a method for screening or identifying therapeutic or prophylactic agents for renal diseases, which comprises assaying a test substance for the activity of up-regulating the expression of fatty acid-binding protein (FABP), and novel mouse proximal renal tubular epithelial cell lines useful therein. The present invention also provides therapeutic or prophylactic agents for renal diseases comprising, as an active ingredient, an agent having activity of up-regulating FABP expression; agents for up-regulating the expression of FABP, and for treating or preventing renal diseases, which comprise a compound having activity of peroxisome proliferator-activated receptor (PPAR) agonist or carnitine palmitoyltransferase (CPT) inhibitor or the like.

Description

[0001] The present invention relates to therapeutic agents for renal diseases and a method for screening and identifying the same. In particular, the present invention relates to a method for screening and identifying such agents, which method was established with close attention directed to the expression of fatty acid-binding protein. The present invention also relates to a cell line established from kidney (proximal renal tubule) cells.[0002] Renal diseases such as nephritis generally presents complex and different pathological aspects, and, when become chronic, may cause serious progression including glomerulosclerosis or interstitial fibrosis, and eventually renal insufficiency. Accordingly, an appropriate treatment in the earlier stage is highly demanded, but there are few therapeutic drugs effective for such purpose. Among the limited number of available drugs, steroids show clear effect but can be accompanied by unacceptably strong adverse side effects. Accordingly, there ha...

AI Technical Summary

Benefits of technology

[0011] Recently, the high proteinuria is regarded as not only a mere indication of renal injury but also one of risky factors per se (Kees-Folts et al., Kidney International, vol. 45, p. 1697-1709, 1994; Eddy et al., Journal of American Society of Nephrology, vol. 5, p. 1273-1287, 1994). It has been known that albumin, a main component of urine, is generally associated with several free fatty acid molecules. Fatty acids binding to urinary proteins are considered to be reabsorbed from brush border membrane of proximal renal tubular epithelial cells, and intracellularly bound to FABP, transported to mitochondria or peroxisome and undergone .beta.-oxidation. In the absence of sufficient amount of FABP, normal .beta.-oxidization of fatty acids can be hindered, which may stimulates the generation of lipid factors (kidney injury factor) that activate macrophages, and lead to the development of interstitial fibrosis via immunological mechanism. In such a case, enhancement of expression of FABP in proximal renal tubular epithelial cells can normalize the fatty acid metabolism and suppress the generation of lipid factor having renal injuring activity and thereby contributing to the improvement of pathology of renal disease.

[0025] When an increased amount of FABP is expressed in the presence of a test substance (or in administration group), it is determined that said substance has up-regulating activity corresponding to the degree of effect, and can be useful as therapeutics for renal diseases. The screening of therapeutic agents for renal diseases can be conveniently conducted by selecting substances having high FABP up-regulating activity as candidates.

[0035] When the present method is carried out in vitro using cultured cells, it is preferred to use animal cells (mammal cells or the like). Above all, cells from kidney of animals are preferred, renal tubular cells are more preferred and proximal renal tubular epithelial cells are especially preferred. Cells to be used may be primary cultured cells or immortalized cells (cell lines). Immortalized cells (cell lines) are advantageously used in view of facilitated cultivation and handling.

[0042] Among the above-mentioned renal tubule-derived cell lines, LLC-PK1 does not maintain the property (3) that is characteristic to proximal renal tubular cells in living body, although said cell line is epithelial cells originated from proximal renal tubule. See, Example 2 below. In contrast to this, the cell lines that have been established by the present inventors definitely maintain the entire properties characteristic to proximal renal tubular epithelial cells including responding activity to hormone, and hence the use thereof should make the system more close to the in vivo physiological environment. Accordingly, these cells can be advantageously used to establish an effective method of screening and identifying therapeutic agents for renal diseases.

Problems solved by technology

Renal diseases such as nephritis generally presents complex and different pathological aspects, and, when become chronic, may cause serious progression including glomerulosclerosis or interstitial fibrosis, and eventually renal insufficiency.

Accordingly, an appropriate treatment in the earlier stage is highly demanded, but there are few therapeutic drugs effective for such purpose.

Among the limited number of available drugs, steroids show clear effect but can be accompanied by unacceptably strong adverse side effects.

However, nothing has been known about the correlation between FABP and renal diseases so far.

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