Basiorka AA, et al. - Researchers assessed whether ASC specks, defined as polymerized large, filamentous clusters of speck-like protein containing a CARD (PYCARD, commonly known as ASC) adaptor protein formed during NLRP3 inflammasome assembly in myelodysplastic syndromes may serve as a biomarker for pyroptotic cell death in myelodysplastic syndromes. Findings highlighted the pathobiological relevance of ASC specks. Moreover, the utility of ASC specks as a sensitive and specific candidate plasma biomarker in affording an index of medullary pyroptotic cell death and ineffective hemopoiesis in patients with myelodysplastic syndromes was suggested.

Methods

• For this observational cohort study conducted at the H Lee Moffitt Cancer Center (Tampa, FL), researchers recruited patients with myelodysplastic syndromes, healthy controls, and patients with non-myelodysplastic syndrome hematological cancers or type 2 diabetes.
• ASC specks in peripheral blood and bone marrow plasma samples were visualized by using confocal and electron microscopy and quantified using flow cytometry.
• They used t test or ANOVA to compare speck percentages, Spearman's rank correlation coefficient to evaluate correlations, and receiver operating characteristics and area under the curve (AUC) analysis to evaluate biomarker efficiency.

Results

• Between January 1, 2005 and January 12, 2017, they collected samples from 177 patients with myelodysplastic syndromes and 29 healthy controls for the discovery cohort.
• During same time period, samples were obtained from 113 patients with myelodysplastic syndromes and 31 healthy controls for the validation cohort.
• Samples were also obtained from 22 patients with del(5q) myelodysplastic syndromes, 230 patients with non-myelodysplastic syndrome hematological cancers and 23 patients with type 2 diabetes.
• In the 177 patients with myelodysplastic syndromes vs the 29 age-matched, healthy donors, a significantly higher log ₁₀-transformed mean percentage of peripheral blood plasma-derived ASC specks was observed after adjustment for glucose concentration (-0.41 [SD 0.49] vs-0.67 [0.59], p=0.034).
• Findings revealed that compared to the percentages of ASC specks in samples from individuals with every other hematological cancer studied (all p < 0.05) except myelofibrosis (p=0.19), those in samples from patients with myelodysplastic syndromes were significantly greater.
• In the independent validation cohort (p < 0.0001), the findings were corroborated.
• A significantly greater mean percentage of peripheral blood plasma ASC specks was observed in patients with at least two somatic gene mutations vs patients with one or no mutation (-0.22 [SD 0.63] vs -0.53 [0.44], p=0.008).
• Results demonstrated that the percentage of plasma ASC specks represented a robust marker for pyroptosis in myelodysplastic syndromes (AUC=0.888), in which a cutoff of 0.80 maximized sensitivity at 0.84 (95% CI 0.65–0.91) and specificity at 0.87 (0.58–0.97).