The autoimmune tautology with a focus on antiphospholipid syndrome

Multiple autoimmune syndrome: Clinical, immunological and genotypic characterization

INTRODUCTION

The existence of subphenotypes common to several autoimmune diseases (AIDs) suggests a shared physiopathology - autoimmune tautology. Multiple Autoimmune Syndrome (MAS) - the coexistence of three or more AIDs in one person-, best illustrates that polyautoimmunity is more than a coincidence.

OBJECTIVES

Characterize and compare the monoautoimmune and MAS patients. Understand if clustering of AIDs leads to differences in disease severity, autoantibodies expression or genetic polymorphisms that could be markers for polyautoimmunity.

METHODS

Currently adult patients were selected from unit cohort. MAS was assumed when ≥3 AIDs were present. 343 patients were included after exclusion criteria: having two AIDs or undetermined diagnosis. Clinical and immunological data were collected from medical files. HLA-DRB1 was genotyped by PCR-SSP methodology and PTPN22(rs2476601) polymorphisms by TaqMan Real Time PCR. Data were analysed using Chi-Square, Fisher's exact tests and logistic regression. Odds ratios (OR) and 95% confidence intervals were calculated.

RESULTS

In comparison with control population: ELEVATED FREQUENCIES: HLA-DRB1*03 in study cohort (OR=3.68,p<0.001) and in monoautoimmune SLE (OR=2.79,p<0.001) and SjS (OR=8.27,p<0.001); HLA-DRB1*15 in monoautoimmune SjS (OR=2.39,p = 0.011); HLA-DRB1*16 in MAS SLE (OR=2.67,p = 0.031); PTPN22_T in all groups except monoautoimmune SjS and triple positive systemic MAS.

DIMINISHED FREQUENCIES

HLA-DRB1*11 in study cohort (OR=0.57,p = 0.013), in MAS SLE (OR=0.39,p = 0.031) and monoautoimmune SjS (OR=0.10,p = 0.005); HLA-DRB1*13 in study cohort (OR=0.52,p = 0.001) and in monoautoimmune SLE (OR=0.53,p = 0.009) and SjS (OR=0.38,p = 0.031); HLA-DRB1*14 in study cohort (OR=0.32,p = 0.013) and monoautoimmune SLE (OR=0.21,p = 0.021); SLE group: HLA-DRB1*07 frequency was higher in monoautoimmune patients (OR=0.43,p = 0.023). MAS patients had significantly more NPSLE (OR=2.99,p<0.001), subacute cutaneous lesions (OR=2.30,p = 0.037), muscle&tendon (OR=2.00,p = 0.045), and haematological (OR=3.18,p = 0.006) involvement and Raynaud's (OR=2.94,p<0.001). SjS group: MAS patients had more frequently cryoglobulins (OR=2.96,p = 0.030), low complement (OR=2.43,p = 0.030) and Raynaud's (OR=4.38,p<0.001); monoautoimmune patients had more parotid enlargement (OR=0.12,p<0.001). APS group: MAS patients had more non-thrombotic manifestations (OR=4.69,p = 0.020) and Raynaud's (OR=9.12,p<0.001). Triple positive systemic MAS (SLE+SjS+APS) had more frequently severe kidney involvement (OR=11.67,p = 0.021) and CNS thrombosis (OR=4.44,p = 0.009). Anti-U1RNP increased frequency was transversally attributable to MAS.

CONCLUSIONS

The coexistence of AIDs contributes to a more severe disease course. We confirmed previously established genetic risk and protection factors and suggest a new protective one - HLA-DRB1*14. HLA-DRB1*07 and anti-U1RNP could be markers for mono and polyautoimmunity, respectively; HLA-DRB1*13 could be a predictor for vascular risk in patients with multiple AIDs. PTPN22(rs2476601) polymorphism could be associated with less severe disease.

The Solitary Blue Toe: A Unique Presentation of Antiphospholipid Syndrome

Antiphospholipid syndrome is an autoimmune disease characterized by vascular thrombosis involving both the arterial and venous systems that can lead to tissue ischemia or end-organ damage. Much of the literature describes various symptoms at initial presentation, but isolated tissue ischemia manifesting as a solitary blue toe is unusual. We discuss a case of a 23-year-old man who presented to the emergency department with a solitary blue fourth digit with minimal erythema and edema, who was suffering from exquisite pain. Following an extensive workup, the patient was diagnosed with antiphospholipid syndrome with thrombi of the vasculature in their lower extremity. With therapeutic anticoagulation, the patient's symptoms subsided and amputation of the digit was prevented.