Routine Cerebrospinal Fluid Cytology Reveals Unique Inclusions in Macrophages During Treatment With Nusinersen

Abstract

Background: Spinal muscular atrophy (SMA) is an autosomal recessive neurodegenerative disorder characterized by degeneration of spinal motor neurons leading to muscular weakness. The antisense oligonucleotide nusinersen was approved for the treatment of patients with 5q-associated SMA. Treatment must be repeatedly administered intrathecally by lumbar puncture. So far, data regarding cerebrospinal fluid (CSF) parameters are sparse and examinations of CSF cytology during nusinersen treatment are completely missing. Methods: 87 CSF samples from 19 adult SMA patients who underwent repeated lumbar punctures for intrathecal injections of nusinersen were investigated. CSF specimens were quantitatively assessed regarding leukocyte subpopulations by routine cytology after Pappenheim staining. A control group with 38 CSF samples from 10 patients with repeated lumbar punctures due to other diseases was used. Results: Treatment with nusinersen did not result in persistent inflammatory cellular changes or a relevant shift of leukocyte subpopulations in the CSF. During nusinersen therapy unique macrophages with numerous sharply defined purple and granular inclusions were detected in all patients. These macrophages were not found in CSF of patients with other diseases who underwent repeated lumbar punctures. Discussion: Routine CSF cytology performed by experienced personnel represents an important and feasible tool for safety monitoring during treatment with intrathecally administered therapeutics. Analysis of leukocyte subpopulations did not raise safety concerns during nusinersen therapy. The potential significance of the unique phagocytic cells for disease course and treatment response needs to be further elucidated in the future.

Cerebrospinal fluid proteomic profiling in nusinersen‐treated patients with spinal muscular atrophy

“…Here, we present a non‐targeted, control‐matched CSF proteomic analysis in adult patients with later‐onset SMA in correlation with clinical outcome, immediately before (T 0 ) and 10 months after initiation of nusinersen treatment (T 10 ), along with changes in basic CSF parameters (Figure a). Concordant with recent findings from another group (Gingele et al, ), we observed a higher number of reactive mononuclear cells in CSF of nusinersen‐treated patients compared with baseline and controls (Table ). We also found a consistent increase in CSF total protein (Table ; Fig.…”

“…However, this increase did not reach the level of significance in our patient cohort ( p = .07). A recent study detected reactive immune cells in the CSF of nusinersen‐treated patients (Gingele et al, ). In our cohort, 2/10 SMA patients had few activated lymphocytes in the CSF at T 0 and 6/10 patients had mononuclear and/or phagocytic cells at T 10 .…”

Unusual inclusions in cerebrospinal fluid macrophages of spinal muscular atrophy patients treated with nusinersen

“…6 As nusinersen is administered intrathecally, a recent study examined the cerebrospinal fluid (CSF) of patients for any adverse effects. 7 The investigators noted macrophages with bizarre inclusions without clear inflammatory sequelae or adverse effects. Here, we report two cases with similar CSF findings.…”

“…The presence of these inclusion-laden macrophages is now well-documented in patients receiving nusinersen and may be transitory as seen in our patients and by others. 7 However, the composition of the inclusions remains unclear. While it is tempting to assume the inclusions contain ASO particles, no definitive evidence confirms this.…”

The light at the end of the tunnel gets vivid for spinal muscular atrophy

“…Although other basic parameters remained unchanged, 2 of 10 patients had activated lymphocytes and 6 patients had mononuclear phagocytic cells in CSF indicating induction of innate immunity either mediated by repeated lumbar puncture or by nusinersen's direct effect, which is still not understood. However, Gingele et al have demonstrated the presence of macrophage in CSF of nusinersen‐treated patients and that was not found in patients suffering from other disease and underwent repeated lumbar puncture (Gingele et al, ), signifying that nusinersen can be a cause for immune induction in patients over prolonged use. Additionally, since all patients do not equally respond to this therapy and the long‐term tolerability and safety of nusinersen are still unknown, investigations on experimental combination therapy are also reported (Pagliarini et al, ).…”