Bcl-2 expression and apoptosis in nephrotoxic nephritis

The product of the Bcl-2 proto-oncogene has been shown to prolong cell survival by preventing apoptosis in several cell lineages. To investigate the regulatory mechanisms of apoptosis in glomerulonephritis, we examined the expression pattern of the Bcl-2 protein together with cellular events in rat nephrotoxic nephritis. Bcl-2 protein and proliferating cell nuclear antigen were detected in glomeruli by immunohistochemistry. Morphologic changes of apoptosis were identified by electron and light microscopy and an in situ DNA nick end labeling method. The first (heterologous) phase began with significant neutrophil infiltration shortly after the injection of nephrotoxic serum. Both Bcl-2 expression and the number of proliferating cells in the glomeruli were at maximum at 24 h in the heterologous phase. Glomerular hypercellularity with an influx of macrophages and the number of apoptotic glomerular cells peaked on day 14 in the second (autologous) phase. Glomerulonephritis resolved after that. These results suggest that overexpression of the Bcl-2 protein may play a role in glomerular cell survival and exacerbation of glomerulonephritis. Apoptosis may occur as an active mechanism in the resolution of the autologous phase in nephrotoxic nephritis.

Inhibition of rheumatoid synovial fibroblast proliferation by antisense oligonucleotides targeting proliferating cell nuclear antigen messenger RNA

OBJECTIVE

To evaluate the feasibility of antisense oligonucleotides as therapeutic agents to inhibit synovial cell growth in rheumatoid arthritis (RA).

METHODS

Fibroblast-like cells established from RA synovium were stimulated with interleukin-1beta (IL-1beta) and treated with antisense or sense oligonucleotides targeting proliferating cell nuclear antigen (PCNA) messenger RNA (mRNA). Proliferation of these cells was determined by 3H-thymidine incorporation. Effects of antisense oligonucleotides on the expression of mRNA and protein were evaluated by reverse transcriptase-polymerase chain reaction and immunohistochemical staining, respectively.

RESULTS

Antisense oligonucleotides targeting PCNA inhibited IL-1-stimulated fibroblast proliferation, whereas sense oligonucleotides had no effect. Both mRNA and protein levels of PCNA were suppressed in the cells treated with antisense oligonucleotides, indicating that the antiproliferative effect was occurring through an antisense mechanism.

CONCLUSION

These results suggest that antisense strategies designed to suppress PCNA expression have potential use as therapeutic agents for RA.

Antisense oligonucleotides to proliferating cell nuclear antigen and Ki-67 inhibit human mesangial cell proliferation

Proliferating cell nuclear antigen (PCNA) and Ki-67 are cell cycle-associated nuclear proteins and are used as markers for proliferating cells. This study attempted to inhibit glomerular mesangial cell (MC) proliferation, which is the hallmark of many forms of glomerular disease, by inhibiting these nuclear proteins with antisense oligodeoxynucleotides. The antisense and sense phosphorothioate oligodeoxynucleotides complementary to PCNA and Ki-67 mRNA, including the initiation codon, were synthesized. Human MC were cultured in growth medium in the presence of sense or antisense oligodeoxynucleotides, and the effects of these oligodeoxynucleotides on mesangial cell proliferation were evaluated by direct cell count. Both PCNA and Ki-67 antisense oligodeoxynucleotides significantly inhibited mesangial cell proliferation as compared with sense oligodeoxynucleotides. Antisense oligodeoxynucleotides (10 microM) for PCNA and Ki-67 inhibited mesangial cell growth by greater than 50%. The effect of antisense oligodeoxynucleotides on target protein expression was examined by immunocytochemistry using specific monoclonal antibodies. Reverse transcription-polymerase chain reaction also was performed to evaluate the effect of antisense oligodeoxynucleotides on PCNA and Ki-67 mRNA expression. Studies of target protein and mRNA expression revealed that the inhibitory effects of the antisense oligonucleotides were mediated through decreases in the expression of both mRNA and protein. Sense oligodeoxynucleotides produced little effect. These results indicate that antisense oligodeoxynucleotides targeting PCNA and Ki-67 mRNA reduce the expression of these gene products and inhibit mesangial cell proliferation. Moreover, these results suggest the feasibility of antisense strategies designed to inhibit PCNA and Ki-67 expression for the inhibition of mesangial cell proliferation in vivo.

Phenotypic modulation of the mesangium reflected by contractile proteins in diabetes

The phenotypic change of the mesangial cell is considered to play a pivotal role in the accumulation of extracellular matrix in diabetic nephropathy. This investigation was undertaken to evaluate the expression of the various isoforms of contractile proteins in the streptozocin (STZ)-induced diabetic rat kidney and in renal biopsy specimens from patients with diabetic nephropathy. Specific antibodies to myosin heavy chain isoforms (SM1, SM2, SMemb), caldesmon, and alpha-smooth muscle actin and cDNAs for SMemb were used. Increased expression of SMemb at the mRNA and protein levels was demonstrated at 1 week after STZ administration in the rat. Both levels were increased at 4 weeks. Mesangial staining of caldesmon was observed at 4 weeks and that of alpha-smooth muscle actin at 24 weeks. Immunohistochemical mesangial staining of the contractile proteins was pronounced in patients with diabetic nephropathy in contrast to the trace mesangial staining in normal control subjects. These results indicate that the phenotypic change in mesangial cells occurs in the early stages of diabetes and that several stages in phenotypic changes may exist. Expression of the contractile protein isoforms, especially SMemb, should serve as a new marker for the subsequent glomerular hypertrophy and sclerosis.

A patient with sarcoidosis associated with recurrent urolithiasis and tubular injury caused by calcium deposition

A 38-year-old woman was hospitalized in January 1994 with renal dysfunction and hypercalcemia. Before admission, she was diagnosed as having urolithiasis, and had been treated twice with extracorporeal shock wave lithotripsy (ESWL). Ophthalmologically, she exhibited iritis and secondary glaucoma. Hypercalcemia, an extremely low titer of parathyroid hormone (PTH), and elevation of angiotensin-converting enzyme (ACE) and lysozyme activity were noted. These findings suggested sarcoidosis, although the chest X-ray showed only fibrotic changes. Hypercalcemia was suspected of having been caused secondarily by sarcoidosis. Since her laboratory data also showed renal dysfunction and abnormal urinalysis, a renal biopsy was performed. The histological findings indicated a tubular and interstitial disorder without glomerular abnormality; calcium deposition, which was detected by X-ray energy dispersive analysis, was observed in the tubular cytoplasm. Administration of prednisolone alleviated the renal dysfunction and decreased the elevation of ACE activity and lysozyme level of the blood. Sarcoidosis is sometimes associated with hypercalcemia, but rarely with renal dysfunction. These findings suggested that sarcoidosis may be associated with renal dysfunction due to tubular injury caused by calcium deposition in the tubules, and that glucocorticoid therapy was effective for these disorders.

A new antibiotic, fumaramidmycin I. Production, biological properties and characterization of producer strain

A new antibiotic, fumaramidmycin, has been isolated from a streptomycete NR-7GG1 which was characterized and named Streptomyces kurssanovii. The strain produced the antibiotic only when grown on agar plates but not in the submerged culture broth, where the contact with the vegetative mycelia appears to cause the inactivation of the antibiotic. The antibiotic shows an antimicrobial activity against both Gram-positive and Gram-negative bacteria.