Association Between NK Cell Genetic Variants and the Development of Long COVID Associated- and Prepandemic Small Fiber Neuropathy, 2024, Graninger+

SNT Gatchaman

Senior Member (Voting Rights)
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Association Between NK Cell Genetic Variants and the Development of Long COVID Associated- and Prepandemic Small Fiber Neuropathy
Marianne Graninger; Verena Endmayr; Laura M. Kühner; Sarah M. Berger; Paulus Rommer; Sigrid Klotz; Ellen Gelpi; Hannes Vietzen; Romana Höftberger; Elisabeth Puchhammer-Stöckl

Long coronavirus disease 2019 (COVID) (LC) symptoms including pain and autonomic dysfunction are in some patients associated with small‐fiber neuropathy (SFN). The pathomechanisms underlying SFN are mostly unclear. Natural killer (NK) cells play a crucial role in immune regulation, viral clearance and nerve metabolism. The aim of this study was to identify associations between development of small‐fiber dysfunction dependent and independent of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection, and human genetic markers associated with specific NK cell functions.

The genetic markers assessed in all cohorts included: FCGR3A, IGHG1, HLA‐E, NKG2C, and rs'916629. Genotyping was performed using TaqMan assays, Sanger sequencing and touchdown polymerase chain reaction. We assessed human cytomegalovirus (HCMV) IgG serostatus in all participants, and screened for anti‐neuronal, anti‐glial and anti‐ganglioside autoantibodies in both patient cohorts. We included 50 LC patients with newly‐emerged symptoms of small‐fiber dysfunction after SARS‐CoV‐2 infection, 27 prepandemic SFN patients and 320 control persons.

Markers associated with low NKG2C response, that is, deletion of the NKG2C gene and lack of prior HCMV infection (IgG seronegativity), occurred significantly more frequently in prepandemic SFN patients compared to LC patients and controls (p = 0.0109 and 0.0005, respectively).

In conclusion, markers of impaired NKG2C pathways are associated with prepandemic SFN, but not with Long COVID‐associated small‐fiber dysfunction.

Link | PDF (Journal of Medical Virology) [Open Access]
 
From discussion —

It is unclear why NKG2C‐mediated pathways differently affect small‐fiber functions in prepandemic SFN versus LC patients. SFN development has been described in the scope of human immunodeficiency virus or hepatitis C virus infection, and in our study, several prepandemic idiopathic SFN patients reported SFN onset shortly after a viral infection, most commonly with Epstein‐Barr virus or influenza virus.

Functional impairment of the NKG2C pathway might be associated with a dysregulation of immune responses after these viral infections, including reduced regulation of autoimmune processes, which might contribute to small‐fiber damage. On the other hand, NK cells are involved in the selective destruction of nerves predamaged by different causes, and SFN could result from ineffective clearance of such pre‐damaged nerves via the NKG2C pathway.
 
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