Accumulation and propagation of hyperphosphorylated Tau (p-Tau) is a common neuropathological hallmark associated with neurodegeneration of Alzheimer's disease (AD), frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17), and related tauopathies. Extracellular vesicles, specifically exosomes, have recently been demonstrated to participate in mediating Tau propagation in brain. Exosomes produced by human induced pluripotent stem cell (iPSC)-derived neurons expressing mutant Tau (mTau), containing the P301L and V337M Tau mutations of FTDP-17, possess the ability to propagate p-Tau pathology after injection into mouse brain. To gain an understanding of the mTau exosome cargo involved in Tau pathogenesis, these pathogenic exosomes were analyzed by proteomics and bioinformatics. The data showed that mTau expression dysregulates the exosome proteome to result in 1) proteins uniquely present only in mTau, and not control exosomes, 2) the absence of proteins in mTau exosomes, uniquely present in control exosomes, and 3) shared proteins which were significantly upregulated or downregulated in mTau compared with control exosomes. Notably, mTau exosomes (not control exosomes) contain ANP32A (also known as I1PP2A), an endogenous inhibitor of the PP2A phosphatase which regulates the phosphorylation state of p-Tau. Several of the mTau exosome-specific proteins have been shown to participate in AD mechanisms involving lysosomes, inflammation, secretases, and related processes. Furthermore, the mTau exosomes lacked a substantial portion of proteins present in control exosomes involved in pathways of localization, vesicle transport, and protein binding functions. The shared proteins present in both mTau and control exosomes represented exosome functions of vesicle-mediated transport, exocytosis, and secretion processes. These data illustrate mTau as a dynamic regulator of the biogenesis of exosomes to result in acquisition, deletion, and up- or downregulation of protein cargo to result in pathogenic mTau exosomes capable of in vivo propagation of p-Tau neuropathology in mouse brain.

The accumulation and propagation of hyperphosphorylated tau (p-Tau) is a neuropathological hallmark occurring with neurodegeneration of Alzheimer's disease (AD). Extracellular vesicles, exosomes, have been shown to initiate tau propagation in the brain. Notably, exosomes from human-induced pluripotent stem cell (iPSC) neurons expressing the AD familial A246E mutant form of presenilin 1 (mPS1) are capable of inducing tau deposits in the mouse brain after in vivo injection. To gain insights into the exosome proteome cargo that participates in propagating tau pathology, this study conducted proteomic analysis of exosomes produced by human iPSC neurons expressing A246E mPS1. Significantly, mPS1 altered the profile of exosome cargo proteins to result in (1) proteins present only in mPS1 exosomes and not in controls, (2) the absence of proteins in the mPS1 exosomes which were present only in controls, and (3) shared proteins which were upregulated or downregulated in the mPS1 exosomes compared to controls. These results show that mPS1 dysregulates the proteome cargo of exosomes to result in the acquisition of proteins involved in the extracellular matrix and protease functions, deletion of proteins involved in RNA and protein translation systems along with proteasome and related functions, combined with the upregulation and downregulation of shared proteins, including the upregulation of amyloid precursor protein. Notably, mPS1 neuron-derived exosomes displayed altered profiles of protein phosphatases and kinases involved in regulating the status of p-tau. The dysregulation of exosome cargo proteins by mPS1 may be associated with the ability of mPS1 neuron-derived exosomes to propagate tau pathology.

Coccidioides is an endemic fungus that causes infections ranging from mild respiratory illness to life-threatening disease, and immunocompromised hosts such as solid organ transplant recipients are at higher risk for disseminated infection and mortality. Our center administers fluconazole prophylaxis to kidney transplant recipients residing in geographic areas with higher incidences of coccidioidomycosis. However, because drug-drug interactions occur between triazoles and immunosuppressants used in transplant medicine, we undertook a study to ascertain whether fluconazole prophylaxis was associated with any important safety outcomes in kidney transplant recipients. This retrospective study evaluated patients who had undergone kidney transplantation between 2016 and 2019. Data on patient demographics, transplant-related clinical information, use of fluconazole prophylaxis (200 mg daily for 6-12 months post-transplant), and patient outcomes were obtained. The primary outcome was mean estimated glomerular filtration rate (eGFR) at 12 months, comparing those who received fluconazole prophylaxis to those who did not. Secondary outcomes included mean eGFR at 3 months, 6 months, and 9 months post-transplant, patient survival, biopsy-proven graft rejection, graft loss, or a new requirement for post-transplant dialysis, all within 12 months post-transplant. The mean eGFR at 12 months was similar between both groups, with 66.4 ml/min/1.73 m² in the fluconazole prophylaxis group vs. 64.3 ml/min/1.73 m² in the non-fluconazole prophylaxis group (P = 0.55). Secondary outcomes were similar across both groups. Multivariable linear regression found no significant association between fluconazole use and graft function. Fluconazole prophylaxis for prevention of coccidioidomycosis was not associated with adverse graft outcomes in kidney transplant recipients.