Inflammatory profiling of patients with familial amyloid polyneuropathy

Abstract

Background: Familial amyloid polyneuropathy (FAP) or ATTRv (amyloid TTR variant) amyloidosis is a fatal hereditary disease characterized by the deposition of amyloid fibrils composed of transthyretin (TTR). The current diagnosis of ATTRv relies on genetic identification of TTR mutations and on Congo Red-positive amyloid deposits, which are absent in most ATTRv patients that are asymptomatic or early symptomatic, supporting the need for novel biomarkers to identify patients in earlier disease phases allowing disease control.

Methods: In an effort to search for new markers for ATTRv, our group searched for nine inflammation markers in ATTRv serum from a cohort of 28 Brazilian ATTRv patients.

Results: We found that the levels of six markers were increased (TNF-α, IL-1β, IL-8, IL-33, IFN-β and IL-10), one had decreased levels (IL-12) and two of them were unchanged (IL-6 and cortisol). Interestingly, asymptomatic patients already presented high levels of IL-33, IL-1β and IL-10, suggesting that inflammation may take place before fibril deposition.

Conclusions: Our findings shed light on a new, previously unidentified aspect of ATTRv, which might help define new criteria for disease management, as well as provide additional understanding of ATTRv aggressiveness.

Keywords: Amyloid; Biomarkers; Cytokines; Familial amyloid polyneuropathy; Transthyretin.

Fig. 1

Sera from ATTRv patients exhibit altered immune response. Serum from 28 patients diagnosed positive for ATTRv and 24 age- and sex-matched healthy subjects were collected, and nine different cytokines and immune system associated-molecules were measured: IL-8 (a), IL-33 (b), IL-1β (c), TNF-α (d), IL-10 (e), IL-12 (f), IFN-β (g), IL-6 (h) and cortisol (i). Data were analyzed using unpaired Student’s t test followed by Mann Whitney test. *p < 0.05, **p < 0.01 and ***p < 0.001

Fig. 2

Sera from asymptomatic and symptomatic ATTRv patients exhibit altered immune response. Serum from 28 patients diagnosed positive for ATTRv and 24 age- and sex-matched healthy subjects were collected, and nine different cytokines and immune system associated-molecules were measured: IL-8 (a), IL-33 (b), IL-1β (c), TNF-α (d), IL-10 (e), IL-12 (f), IFN-β (g), IL-6 (h) and cortisol (i). ATTRv patients were scored by Coutinho index (12) and separated by aggressiveness: FAP 0 = asymptomatic; FAP 1 = mild symptoms; FAP 2–3 = moderate to aggressive symptoms. Data were analyzed using unpaired one-way ANOVA followed by Kruskal-Wallis test. *p < 0.05, **p < 0.01 and ***p < 0.001