Kidney Biopsy Findings and Clinical Outcomes of US Veterans with Inflammatory Bowel Disease.

Introduction: Patients with inflammatory bowel disease (IBD; ulcerative colitis [UC] and Crohn's disease [CD]) may have unique patterns of kidney injury related to their underlying or coexisting disease or to medications. We present the kidney biopsy findings and clinical outcomes of veterans with UC or CD from the US Department of Veteran's Affairs (VA) health system. Methods: Histopathologic and clinical data were extracted by retrospective review of the VA electronic health record of patients with IBD and a kidney biopsy between 2000 and 2018. Incident end-stage kidney disease (ESKD) was defined as requirement of kidney replacement therapy. Statistical analyses were performed using SAS. Results: A total of 140 patients (UC: 91 and CD: 49) underwent kidney biopsy. The three most common diagnoses were IgA nephropathy (17.1%), diabetic nephropathy (14.3%), and acute interstitial nephritis (9.3%). Significant interstitial fibrosis, tubular atrophy, and arteriosclerosis were present in 45% of biopsies. Twenty-six percent of patients with UC and 20% of those with CD progressed to ESKD, with a mean time from kidney biopsy of 3.1 and 1.9 years, respectively. Forty-five percent of patients with UC and 34% of those with CD died, with a mean time from kidney biopsy of 4.3 and 4.6 years, respectively. Conclusion: Among US veterans with IBD who underwent a kidney biopsy, IgA nephropathy, diabetic nephropathy, and interstitial nephritis were among the most common findings. Additionally, features of advanced kidney disease with rapid clinical progression to ESKD or death were observed. These findings suggest a delay and possibly a low rate of diagnosis.

TFG regulates secretory and endosomal sorting pathways in neurons to promote their activity and maintenance.

Molecular pathways that intrinsically regulate neuronal maintenance are poorly understood, but rare pathogenic mutations that underlie neurodegenerative disease can offer important insights into the mechanisms that facilitate lifelong neuronal function. Here, we leverage a rat model to demonstrate directly that the TFG p.R106C variant implicated previously in complicated forms of hereditary spastic paraplegia (HSP) underlies progressive spastic paraparesis with accompanying ventriculomegaly and thinning of the corpus callosum, consistent with disease phenotypes identified in adolescent patients. Analyses of primary cortical neurons obtained from CRISPR-Cas9-edited animals reveal a kinetic delay in biosynthetic secretory protein transport from the endoplasmic reticulum (ER), in agreement with prior induced pluripotent stem cell-based studies. Moreover, we identify an unexpected role for TFG in the trafficking of Rab4A-positive recycling endosomes specifically within axons and dendrites. Impaired TFG function compromises the transport of at least a subset of endosomal cargoes, which we show results in down-regulated inhibitory receptor signaling that may contribute to excitation-inhibition imbalances. In contrast, the morphology and trafficking of other organelles, including mitochondria and lysosomes, are unaffected by the TFG p.R106C mutation. Our findings demonstrate a multifaceted role for TFG in secretory and endosomal protein sorting that is unique to cells of the central nervous system and highlight the importance of these pathways to maintenance of corticospinal tract motor neurons.