N-glycans as potential novel biomarkers for kidney injury in avian species

In avian species, kidney injury is caused by various factors, such as non-steroidal anti-inflammatory drugs (NSAIDs) and heavy metals (Pb and Hg). In fact, diclofenac, an NSAID, has caused serious damage to vultures in the... [ view full abstract ]

In avian species, kidney injury is caused by various factors, such as non-steroidal anti-inflammatory drugs (NSAIDs) and heavy metals (Pb and Hg). In fact, diclofenac, an NSAID, has caused serious damage to vultures in the Indian subcontinent. The population of three vulture species has declined by more than 95% due to renal lesions caused by uptake of diclofenac. The avian kidney is vulnerable to various materials because of the abundant blood flow into the kidney from renal portal veins. However, evaluation of levels of renal dysfunction is difficult in avian species because of the kidney’s complex structure. Based on the above, the objective of our study is to identify a novel kidney biomarker in birds. Glycomics has been at the forefront of biological and medical sciences for the past decade and glycans are used as biomarkers of carcinoma in humans. In this study, kidney-damaged model chicken (Gallus gallus domesticus) was created by the administration of diclofenac sodium. From the results of histopathological examination, kidney-damaged chickens were selected for analysis of plasma N-glycan using the glycoblotting method, which can be used for high-throughput analysis of biological samples. In our chickens, 38 N-glycans were detected and levels of 16 glycans had changed between pre- and post-administration in renal damaged chickens and kidney injury was associated with increased levels of both sialylated and non-fucosylated glycans. Some of these glycans had the same presumptive composition which increased in patients of renal carcinoma. Therefore, these 16 glycans have the possibility to be a novel renal marker in avian species. As a further study, we would like to examine the plasma of wild birds which have kidney damage and healthy samples of the same species to evaluate the usefulness of these glycans as candidate biomarkers, and ultimately develop a simple diagnosis kit of kidney damage.