Immunobiologic factors in the pathogenesis of renal infection

Cytokine and lymphocyte activation during experimental acute pyelonephritis

We studied the cellular and humoral events which follow experimental acute pyelonephritis from P-fimbriated Escherichia coli to gain insight into the relationships among cells and specifically cytokines to determine how early events in untreated infection lead to renal damage. Cynomolgus (Macaca fascicularis) monkeys were studied after they were subjected to unilateral ureteral bacterial inoculation. We evaluated the blood for leukocytosis and studied lymphocyte subsets using flow cytometry and monoclonal antibodies to the subsets and serum, complement, cytokines and antibody titers. Interleukin-1, 2 and 6 and tumor necrosis factor (TNF) were assayed by enzyme-linked immunoadsorbent assay (ELISA), using monoclonal and polyclonal antibodies. Leukocytosis was marked and there were significant elevations in serum cytokines, interleukin-1 alpha, 2 and 6 with only small changes in the level of TNF. Interleukin-2 levels were sustained and may have upregulated the homing receptor for virgin lymphocytes. The studies illustrated the unique relationship between cytokines and lymphocytes and the response to bacterial infection, showing that the inflammatory response is regulated not only by cytokine activity but also by lymphocyte activation.

Aggravation by morphine and D-aspartic acid of pyelonephritis induced by i.v. inoculation of Staphylococcus aureus in rats

Experimental pyelonephritis was induced by intravenous inoculation of Staphylococcus aureus in homozygous Brattleboro diabetes insipidus (Hom Brattleboro DI), heterozygous Brattleboro (Het Brattleboro) and Wistar rats. One group of rats from each strain was implanted with morphine-containing pellet three days before inoculation. Another series of groups received D-aspartic acid (D-ASP) intraperitoneally, starting three days before inoculation throughout the experiments. Owing to the inhibition by morphine or D-ASP of food intake, another control group from each strain was subjected to food restriction. Pyelonephritis development on the tenth day of inoculation was evaluated by the determination of viable bacteria in urine and total kidney tissue, and pathomorphological lesions in kidney. Hom Brattleboro DI rats appeared more resistant. Morphine or D-ASP significantly increased the findings in three strains of rat.

Experimental pyelonephritis and papillary necrosis in the Gunn rat

Homozygous and heterozygous female Gunn rats show increased susceptibility to experimental urinary infection. The strain develops pyelonephritis after intravesical inoculation of Proteus mirabilis in numbers which fail to induce the lesion in albino rats, and severe pyelonephritis is frequently complicated by papillary necrosis. The basis for this enhanced susceptibility has not been defined, but the occurrence of the phenomenon in both homozygous and heterozygous rats indicates that it is not caused primarily by high plasma levels of unconjugated bilirubin or by the deposition of bilirubin in the tip of the renal papilla. The increased susceptibility of the homozygous Gunn rat to ascending urinary tract infection provides supporting evidence for the suggestion that infection may complicate the natural history of experimental analgesic nephropathy in this strain and is relevant to the clinical association of analgesic nephropathy and urinary infection.

Renal disease in the geriatric patient

Although there are physiologic and anatomic changes of the kidney that occur almost universally with aging, no specific kidney disease that is totally confined to the geriatric population has been identified. Kidney diseases that predominate in the elderly include vascular and atheroembolic diseases, obstructive nephropathies, nephropathies secondary to certain systemic diseases, and intrinsic kidney disease. An understanding of the age-related changes of renal architecture and function is necessary to distinguish them from actual diseases that affect the aged kidney. These changes and their probable consequences for the geriatric patient are reviewed. We then discuss particular aspects of renal diseases that occur more commonly or have unique age-related manifestations in the elderly.