Autopsy of the body of a 40-year-old woman, who died of uremia, shows enlarged variegated kidneys In the kidneys, the glomerular capillary membranes are thickened and resemble "wire loops"; there are foci of fibrinoid necrosis in their walls and hyaline thrombi in their lumina. In the nuclei, there are hematoxylin bodies. In the heart, Libman-Sacks endocarditis is observed. What renal disorder is the most likely in this case?