Renal Thrombotic Microangiopathy in Concurrent COVID-19 Vaccination and Infection

We report on the development of nephrotic proteinuria and microhematuria, with histological features of renal thrombotic microangiopathy (TMA), following the first dose of BNT162b2 COVID-19 vaccine (Pfizer-BioNTech) and COVID-19 diagnosis. A 35-year-old previously healthy man was admitted at our hospital due to the onset of foamy urine. Previously, 40 days earlier, he had received the first injection of the vaccine, and 33 days earlier, the RT-PCR for SARS-CoV-2 tested positive. Laboratory tests showed nephrotic proteinuria (7.9 gr/day), microhematuria, serum creatinine 0.91 mg/dL. Kidney biopsy revealed ultrastructural evidence of severe endothelial cell injury suggestive of a starting phase of TMA. After high-dose steroid treatment administration, complete remission of proteinuria was achieved in a few weeks. The association of COVID-19 with renal TMA has been previously described only in patients with acute renal injury. Besides, the correlation with COVID-19 vaccine has not been reported so far. The close temporal proximity (7 days) between the two events opens the question whether the histological findings should be ascribed to COVID-19 itself or to vaccine injection.

Ultrastructural evidence for an unusual mode of ciliogenesis in mouse multiciliated epithelia

Multiciliogenesis is a cascading process for generating hundreds of motile cilia in single cells. In vertebrates, this process has been investigated in the ependyma of brain ventricles and the ciliated epithelia of the airway and oviduct. Although the early steps to amplify centrioles have been characterized in molecular detail, subsequent steps to establish multicilia have been relatively overlooked. Here, we focused on unusual cilia-related structures previously observed in wild-type mouse ependyma using transmission electron microscopy and analyzed their ultrastructural features and the frequency of their occurrence. In the ependyma, $\sim$5% of cilia existed as bundles; while the majority of the bundles were paired, bundles of more than three cilia were also found. Furthermore, apical protrusions harboring multiple sets of axonemes were occasionally observed (0–2 per section), suggesting an unusual mode of ciliogenesis. In trachea and oviduct epithelia, ciliary bundles were absent, but protrusions containing multiple axonemes were observed. At the base of such protrusions, certain axonemes were completely enwrapped by membranes, whereas others remained incompletely enwrapped. These data suggested that the late steps of multiciliogenesis might include a unique process underlying the development of cilia, which is distinct from the ciliogenesis of primary cilia.

NCMP-09. POSTMORTEM STUDY OF ORGAN SPECIFIC TOXICITY IN GLIOBLASTOMA PATIENTS TREATED WITH A COMBINATION OF TEMOZOLOMIDE, BEVACIZUMAB AND IRINOTECAN

Combined chemotherapy with temozolomide (TMZ), bevacizumab (BEV) and irinotecan (IRI) [TBI] has been used in patients with recurrent or progressive high-grade gliomas. Patients tolerated the regimen well with increased frequency of reversible clinical myelosuppression (CM), hypertension and proteinuria. However, organ-specific toxicities have never been evaluated by post-mortem examination. From 2009 to 2019, post-mortem examinations were performed in seventy-six decedents, including gliomas (N=68, 44/M and 24/F, median age: 59, ranging 23–80 years old) and brain metastases (N=8, 5/M and 3/F, ranging 39–75 years old). Twenty-four glioma subjects were treated with 1–25 cycles TBI (median 5.5) at glioma recurrence. All subjects’ clinical information, treatment histories and adverse events were collected. Five (7.7%, 5/65) glioma decedents (excluding three glioma patients who never received TMZ) permanently discontinued TMZ due to severe CM during concurrent chemoradiation therapy. There is no significantly elevated severity of CM from TBI when compared to standard of care therapies, nor when comparing extended TMZ treatment to the standard 12 cycles of TMZ. However, exposure to IRI significantly increased the CM occurrence (p< 0.05). Among glioma decedents, the most common cause of death was tumor progression (63.2 %, N=43), followed by aspiration pneumonia (48.5%, N=33). No deaths were attributed to acute toxicity from TBI. An electromicroscopic (EM) examination was performed in addition to routine autopsy procedures to investigate the cause of hypertension and proteinuria frequently developing in patients received BEV therapy. Ultrastructural evidence of thrombotic microangiopathy was observed in the kidneys among BEV users; however, it is difficult to conclude such changes were related to BEV due to rapid autolytic changes and artifacts. CONCLUSION: IRI, not the extended use of TMZ, significantly increased the frequency of reversible CM in recurrent glioma patients. There are no unexpected adverse events or organ-specific toxicities detected among glioma decedents who received the TBI regimen.