Interpretation of Kidney Biopsy in Indian Patients Older than 60 Years: A Tertiary Care Experience

The adult population above the age of 60 years has significantly increased in India, with a life expectancy of 68.4 years in 2016. Data regarding the renal histopathology in these patients are scarce though the number of native kidney biopsies done in this subset of population is increasing. The present study is a retrospective analysis of 231 biopsies from a total of 700 biopsies, from patients above 60 years of age (M = 65.8%; F = 34.2%) with a mean age of 64 ± 6.03 years. The indications for kidney biopsy included nephrotic syndrome (NS) (30.4%), nephritic syndrome (19.1%), rapidly progressive renal failure (11.7%), acute kidney injury (AKI) (15.7%), and acute worsening of preexisting chronic kidney disease (CKD) (23%). The median percentage of glomerulosclerosis was 22% (5%–45%), and interstitial fibrosis and tubular atrophy was 30% (10%–50%). The most common cause for nephrotic syndrome was membranous nephropathy (31.4%) and for nephritic syndrome was benign arterionephrosclerosis (22.7%). Postinfectious glomerulonephritis (29.6%) was the leading cause for rapidly progressive renal failure. Acute injury on CKD was notable in patients with diabetic nephropathy (30.2%). The predominant causes for AKI were acute tubulointerstitial nephritis (33.3%), acute tubular necrosis (22.2%), and acute pyelonephritis (19.4%). The biopsy proven histopathological features enabled us in tailoring the therapy. None of the patients developed life-threatening complications following ultrasonography-guided biopsy.

Interleukin 17 induces cartilage collagen breakdown: novel synergistic effects in combination with proinflammatory cytokines

OBJECTIVE

To investigate whether interleukin 17 (IL17), derived specifically from T cells, can promote type II collagen release from cartilage. The ability of IL17 to synergise with other proinflammatory mediators to induce collagen release from cartilage, and what effect anti-inflammatory agents had on this process, was also assessed.

METHODS

IL17 alone, or in combination with IL1, IL6, oncostatin M (OSM), or tumour necrosis factor alpha (TNFalpha), was added to bovine nasal cartilage explant cultures. Proteoglycan and collagen release were determined. Collagenolytic activity was determined by bioassay. Chondroprotective effects of IL4, IL13, transforming growth factor beta1 (TGFbeta1) and insulin-like growth factor-1 (IGF1) were assessed by inclusion in the explant cultures.

RESULTS

IL17 alone stimulated a dose dependent release of proteoglycan and type II collagen from bovine nasal cartilage explants. Suboptimal doses of IL17 synergised potently with TNFalpha, IL1, OSM, and IL6 to promote collagen degradation. This collagen release was completely inhibited by tissue inhibitor of metalloproteinase-1 and BB-94 (a synthetic metalloproteinase inhibitor), and was significantly reduced by IL4, IL13, TGFbeta1, and IGF1. In IL17 treated chondrocytes, mRNA expression for matrix metalloproteinase (MMP)-1, MMP-3, and MMP-13 was detected. Moreover, a synergistic induction of these MMPs was seen when IL17 was combined with other proinflammatory cytokines.

CONCLUSIONS

IL17 can, alone and synergistically in combination with other proinflammatory cytokines, promote chondrocyte mediated MMP dependent type II collagen release from cartilage. Because levels of all these proinflammatory cytokines are raised in rheumatoid synovial fluids, this study suggests that IL17 may act as a potent upstream mediator of cartilage collagen breakdown in inflammatory joint diseases.

Synergistic induction of matrix metalloproteinase 1 by interleukin-1alpha and oncostatin M in human chondrocytes involves signal transducer and activator of transcription and activator protein 1 transcription factors via a novel mechanism

OBJECTIVE

To investigate the mechanism of interleukin-1alpha (IL-1alpha) and oncostatin M (OSM) synergistic regulation of matrix metalloproteinase 1 (MMP-1) in human chondrocytes.

METHODS

Using an immortalized human chondrocyte cell line (T/C28a4), we investigated regulation of the MMP-1 gene. Northern blotting and flow cytometric analysis were used to assess changes in receptor, MMP-1, and c-fos expression. Transient transfections using MMP-1 promoter/luciferase constructs, electrophoretic mobility shift assay, and site-directed mutagenesis were used to investigate MMP-1 promoter activation.

RESULTS

We found no alteration in the expression of receptors used by these cytokines after stimulation with IL-1alpha/OSM. Using MMP-1 promoter/luciferase reporter constructs, we found that the proximal (-517/+63) region of the MMP-1 promoter was sufficient to support a synergistic activation. A role for activated signal transducers and activators of transcription (STAT-3) was demonstrated, although no binding of STAT-3 to the MMP-1 promoter was found. However, constitutive binding of activator protein 1 (AP-1) was detected, and changes in c-fos expression could modulate promoter activity.

CONCLUSION

Since no changes in receptor expression were observed, receptor modulation cannot account for the IL-1alpha/OSM synergy observed. Instead, the interplay of various intracellular signaling pathways is a more likely explanation. STAT activation is required, but STAT proteins do not interact directly with the MMP-1 promoter. We propose that activated STATs stimulate c-fos expression, and changes in expression of the AP-1 components regulate MMP-1 expression. We highlight a new mechanism for MMP-1 regulation in human chondrocytes that could provide potential new therapeutic targets.

Synergistic effects of glycoprotein 130 binding cytokines in combination with interleukin-1 on cartilage collagen breakdown

OBJECTIVE

To determine whether other glycoprotein 130 (gp130) binding cytokines can mimic the effects of oncostatin M (OSM) in acting synergistically with interleukin-1alpha (IL-1alpha) to induce cartilage collagen breakdown and collagenase expression, and to determine which receptors mediate these effects.

METHODS

The release of collagen and proteoglycan was assessed in bovine and human cartilage explant cultures. Messenger RNA (mRNA) and protein production from immortalized human chondrocytes (T/C28a4) was analyzed by Northern blotting and specific enzyme-linked immunosorbent assays. Collagenase activity was measured by bioassay. Cell surface receptors were detected by flow cytometry.

RESULTS

OSM in combination with IL-1alpha caused a rapid synergistic induction of matrix metalloproteinase 1 mRNA, which was sustained over a 72-hour period. Flow cytometric analyses detected both the OSM-specific receptor and the gp130 receptor at the chondrocyte cell surface, but failed to detect the leukemia inhibitory factor receptor (LIFR). Cartilage degradation assays revealed that, of the gp130 binding cytokines, only OSM and IL-6, in the presence of its soluble receptor (sIL-6R), were able to act synergistically with IL-1alpha to promote collagen release.

CONCLUSION

This study demonstrates that IL-6 can mimic OSM in synergizing with IL-1alpha to induce chondrocyte-mediated cartilage collagen breakdown and collagenase production. In order to have this effect, IL-6 requires the presence of its soluble receptor. The apparent absence of LIFR explains why other gp130 binding cytokines do not act in synergy with IL-1alpha. Since OSM, IL-6, and sIL-6R levels have all been shown to be elevated in the rheumatoid joint, our findings suggest that these cytokines may be key mediators of cartilage collagen catabolism in the inflammatory arthritides.

96-Well plate assays for measuring collagenase activity using (3)H-acetylated collagen

We describe two alternative assays for measuring collagenolytic activity using (3)H-acetylated collagen. Both assays have been developed for the 96-well plate format and measure the amount of radiolabeled collagen fragments released into the supernatant from an insoluble (3)H-acetylated collagen fibril preparation. The first method separates digested solubilized fragments from the intact fibril by sedimentation of the undigested collagen by centrifugation. The second method achieves this separation by filtration of the supernatant through the membrane of a 96-well filtration plate which retains the undigested collagen fibril. Both methods give linear dose- and time-dependent responses of collagenase activity > or = 70% of total collagen lysis. In addition, both assays can be simply modified to measure tissue inhibitors of metalloproteinases (TIMPs) inhibitory activity, which is also linear between 20 and 75% of total collagen lysis with the amount of TIMP added.

The role of oncostatin M in animal and human connective tissue collagen turnover and its localization within the rheumatoid joint

OBJECTIVE

To study the interaction of interleukin-1alpha (IL-1alpha) and oncostatin M (OSM) in promoting cartilage collagen destruction.

METHODS

Bovine, porcine, and human cartilage and human chondrocytes were studied in culture. The levels of collagenase (matrix metalloproteinase 1 [MMP-1]) and tissue inhibitor of metalloproteinases 1 (TIMP-1) were measured by bioassay and enzyme-linked immunosorbent assay (ELISA). The levels of OSM in rheumatoid synovial fluid were measured by ELISA.

RESULTS

When combined with OSM, IL-1alpha, IL-1beta, and tumor necrosis factor alpha released proteoglycan and collagen from cartilage. OSM was the only member of the IL-6 family to have this effect. Human tendon also responded to IL-1alpha and OSM. OSM increased the production of MMP-1 and TIMP-1 but when combined with IL-1alpha, synergistically promoted MMP-1 production in human chondrocytes and synovial fibroblasts. High levels of OSM were found in human rheumatoid synovial fluids, and confocal microscopy showed that OSM was produced by macrophages in rheumatoid synovial tissue.

CONCLUSION

These results highlight an important new mechanism by which there is irreversible loss of collagen from cartilage.