Complement abnormalities in acquired lipodystrophy revisited.

Area of Science:

• Immunology
• Endocrinology
• Nephrology

Background:

• Lipodystrophy involves a deficiency in adipocytes, impacting triglyceride storage.
• Acquired lipodystrophy often co-occurs with autoimmune conditions.
• A known subtype features upper body fat loss, alternative complement pathway activation (C3 nephritic factor, low C3), and glomerulonephritis.

Observation:

• A distinct acquired generalized lipodystrophy form was identified.
• This form presented with classical complement pathway activation (low C4) and autoimmune hepatitis.
• Three unrelated patients with lipodystrophy and low C4 levels were studied.

Findings:

• All patients exhibited near-total lipodystrophy, autoimmune hepatitis, and low C4 complement.
• Associated autoimmune diseases included hemolytic anemia, thyroid disease, and polyneuropathy.
• In vitro complement pathway analysis indicated constitutive classical pathway activation.

Implications:

• This lipodystrophy subtype is immunologically distinct from previously described forms.
• Classical pathway activation characterizes this generalized lipodystrophy, unlike the alternative pathway in partial lipodystrophy.
• Tailoring therapies to the specific immunopathogenesis of each lipodystrophy subtype may improve patient outcomes.