Fig 1.
Risperidone/Paliperidone concentrations after 5 days of treatment.
Plasma and bone marrow concentrations of risperidone (white bars) and its active metabolite paliperidone (grey bars) were measured 1 and 3 hours post dosing. Paliperidone concentrations expectedly exceeded risperidone in both plasma and bone marrow. Concentrations of risperidone and paliperidone were found in at least 10-fold excess in bone marrow compared to plasma at both time points.
Fig 2.
Immunological parameters after 4 weeks of treatment.
Levels of 40 different cytokines or chemokines were measured by normalized pixel density (% of reference spots, Y axis) after 4 weeks of continuous risperidone (black bars) or vehicle (grey bars) treatment. Seventeen cytokine/chemokines were significantly (*, P<0.05) reduced in risperidone-treated mice relative to vehicle-treated mice. An additional 5 markers were substantially reduced, with P values ranging between 0.05 and 0.1 (marked). No markers were significantly elevated in risperidone-treated mice.
Fig 3.
Immunological parameters after 5 days of treatment.
Levels of 40 different cytokines or chemokines were measured by normalized pixel density (% of reference spots, Y axis) after 5 days of continuous risperidone (black bars) or vehicle (grey bars) treatment. Measurements were made 1 hour (A) and 3 hours (B) after the fifth dose. Only ICAM1, C5a, and IL-16 were significantly (*, P<0.05) 1 hour post treatment; however, 18 cytokine/chemokines were significantly (*, P<0.05) reduced by 3 hours. Two or 4 additional markers were substantially reduced with P values ranging between 0.05 and 0.1 (marked) at 1 and 3 hours, respectively. IL-6 was significantly elevated in risperidone-treated mice at 1 hour post treatment, but the effect was lost by 3 hours. Markers that were reduced at 1 hour (ICAM1, C5a, and IL-16) all rebounded to normal levels by 3 hours; however, both markers that were trending downward at 1 hour (IP10 and IL-2) were significantly reduced in treated mice by 3 hours.
Table 1.
Cytokine profiles in a preclinical model of RIS therapy.
Fig 4.
Histopathological changes after 5 days of treatment.
Hematoxylin and eosin staining of bone marrow, thymus, and spleen showed changes across cohorts between risperidone- versus vehicle-treated mice. Bone marrow sections (A) from risperidone-treated mice revealed myeloid dysplasia (green arrow heads) and necroptotic cells (green arrows), whereas myeloid progenitors from vehicle-treated mice featured normal myeloid progenitors (silver arrows). Thymus sections (B) from risperidone-treated mice showed hyaline staining, most notably along vessel walls (white arrows), and early steatosis (grey arrow). Cellular changes were not apparent in the spleen between risperidone- and vehicle-treated mice; however, sections viewed at low magnification (C) show a disorganization of white pulp (boxed area) with loss of marginal zones and germinal centers in risperidone-treated mice.
Fig 5.
Immune dysregulation and infectious disease susceptibility during risperidone treatment.
Cytokines measured in this study are integral to several immune function and infectious disease response pathways in the KEGG database. The number of altered cytokines present at wild-type levels at each effect stage (acute/transient effect, early/transient effect, early/persistent effect, or chronic effect) were tabulated in VEH-treated (red) and RIS-treated (green) mice. Chronic exposure measurements reflect the total cytokines that were altered at both 5 days and 4 weeks. Absence of altered cytokines in an effect category are colored black (λ = 0 nm). The intensity of red reflects the number of immune markers significantly decreased during RIS treatment, and consequently the strength of function in VEH-treated mice relative to function in RIS-treated mice, and vice versa regarding green intensity showing an expected enhancement of pathway function. Twenty-seven immune function pathways (A) included measured cytokines, and alterations were apparent in all but the Ras signaling pathway. A small number of pathways were transiently enhanced or depressed by RIS treatment before recovering fully or subsequently becoming dysregulated. Twenty-one pathways include depressed cytokines after five days of RIS treatment, and nineteen were further dysregulated by four weeks. Twenty-three of the twenty-seven immune function pathways had reduction of at least one cytokine after four weeks of RIS treatment. Twenty-four infectious disease response pathways (B) included measured cytokines, and all but Helicobacter infection involve altered cytokines. RIS-treatment would increase susceptibility to Staphylococcus aureus and viral myocarditis acutely after dosing, but would not confer increased risk by continuous therapy. RIS could transiently enhance responses to ten infections, though any enhancement would be offset by parallel reductions of a different immune mediator during responses in six others (shown as equivalent red and green wavelengths, appearing as yellow). After five days of treatment, RIS treatment causes dysregulation of pathways involved in defense against twenty-one different infectious diseases. All disruptions persisted through 4 weeks of treatment, and sixteen of the twenty-one were further dysregulated followed longer drug treatment.