Jochum, A.-K. | bioRxiv Science

bioRxiv2023

Neuropathological assessment of the olfactory bulb and tract in individuals with COVID-19

The majority of patients with Parkinson disease (PD) experience a loss in their sense of smell and accumulate insoluble -synuclein aggregates in their olfactory bulbs (OB). Subjects affected by a SARS-CoV-2-linked illness (COVID-19) frequently experience hyposmia. We previously hypothesized that -synuclein and tau misprocessing could occur following host responses to microbial triggers. Using semiquantitative measurements of immunohistochemical signals, we examined OB and olfactory tract specimens collected serially at autopsies between 2020 and 2023. Deceased subjects comprised 50 adults, which included COVID19+ patients (n=22), individuals with Lewy body disease (e.g., PD and dementia with Lewy bodies (DLB; n=6)), Alzheimer disease (AD; n=3), other non-synucleinopathy-linked degenerative diseases (e.g., progressive supranuclear palsy (PSP; n=2) and multisystem atrophy (MSA; n=1)). Further, we included neurologically healthy controls (HCO; n=9) and those with an inflammation-rich brain disorder as neurological controls (NCO; n=7). When probing for inflammatory changes focusing on anterior olfactory nuclei (AON) using anti-CD68 immunostaining, scores were consistently elevated in NCO and AD cases. In contrast, inflammation on average was not significantly altered in COVID19+ patients relative to controls, although anti-CD68 reactivity in their OB and tracts declined with progression in age. Mild-to-moderate increases in phospho-Syn and phospho-tau signals were detected in the AON of tauopathy-and synucleinopathy-afflicted brains, respectively, consistent with mixed pathology, as described by others. Lastly, when both sides were available for comparison in our case series, we saw no asymmetry in the degree of pathology of the left versus right OB and tracts. We concluded from our autopsy series that after a fatal course of COVID-19, microscopic changes -when present-in the rostral, intracranial portion of the olfactory circuitry generally reflected neurodegenerative processes seen elsewhere in the brain. In general, inflammation correlated best with the degree of Alzheimers-linked tauopathy and declined with progression of age in COVID19+ patients.

pathology↗

bioRxiv2023

Tumor sialylation is a barrier against CD8 T cell-mediated anti-tumor responses and anti-PD-1 resistance in breast cancer

Breast cancer is the most common cancer among women. However, the use of immune checkpoint inhibitors, that have revolutionized treatment of multiple cancers, unfortunately remain largely ineffective in most breast cancer patients. Here, we report the most comprehensive glycoproteome map in breast tumor cells, pointing to a key role of sialic acid modifications in mammary cancer. Genetic and pharmacologic inhibition of sialylation repolarizes the tumor microenvironment, leading to a reduction in myeloid-derived suppressor cells and a significant increase in Tcf7+ memory and CD8+ effector T cells. Mechanistically, sialylation controls cell surface expression of MHC class I and PD-1-ligand on the tumor cells. Functionally, in vivo interference with sialylation on breast cancer cells licenses CD8+ T cells to effectively kill the tumors. In multiple immunotherapy-resistant breast tumor models, we also show that the abrogation of sialylation sensitizes to anti-PD-1 immune checkpoint therapy. We further demonstrate that hyper-sialylation occurs in over half of human breast cancers tested and correlates with poor T cell infiltration. Our results establish sialylation as a central immunoregulator in breast cancer, orchestrating multiple pathways of immune evasion. Targeting tumor sialylation licenses immunologically inert mammary tumors to be efficiently eliminated by anti-cancer immunity and sensitizes to immune checkpoint therapy.

cancer biology↗