Human β-defensin 2 (HBD2) bridges infection defense and allergic inflammation by activating mast cells, with elevated serum levels found in atopic dermatitis, psoriasis, and chronic urticaria — particularly when accompanied by angioedema.
Dual antimicrobial + allergic roleHBD2 both kills pathogens and activates mast cells for allergic responses — explaining why skin infections often trigger or worsen allergic skin diseases like atopic dermatitis and urticaria
What the researchers found
HBD2 promotes mast cell activation and degranulation, linking antimicrobial defense to allergic reactions. Elevated serum HBD2 found in atopic dermatitis, psoriasis, and chronic spontaneous urticaria. CSU patients with angioedema have higher HBD2 than those without. HBD2 is produced by keratinocytes, epithelial cells, and macrophages in response to microorganisms or pro-inflammatory cytokines.
Why it matters
Understanding how antimicrobial peptides like HBD2 trigger allergic responses explains why skin infections often worsen allergic diseases. This dual-function concept could lead to new therapeutic strategies — either dampening HBD2's allergic effects while preserving antimicrobial function, or using HBD2 levels as a biomarker to guide treatment decisions in skin diseases.
The numbers in context
HBD-2 is produced by epithelial cells, keratinocytes, and macrophages in response to microbial exposure or pro-inflammatory cytokines.
How the study worked
Narrative review of published literature on human β-defensin 2 in dermatological and allergic conditions, covering its production, antimicrobial functions, role in mast cell activation, and clinical associations with skin diseases.
Who was studied
Skin biology — antimicrobial and allergic immune responses
What this study cannot tell us
Narrative review without systematic methodology. Limited data on HBD2 skin expression levels in allergic diseases (most studies measure serum levels). The causal relationship between elevated HBD2 and allergic disease is not established — HBD2 elevation could be a consequence rather than a cause. Published in a regional dermatology journal with potentially limited peer review scope.
How to read the evidence
Preliminary to moderate — the antimicrobial and mast cell-activating functions of HBD2 are well-established, but clinical associations with specific skin diseases are based on relatively small studies.
When this study was published
Published in 2024, synthesizing the current understanding of HBD2's immunological dual role in skin diseases.
The bigger picture
The relationship between infections and allergies has puzzled immunologists for decades. HBD2 provides a molecular link — the same peptide that fights infection can also activate allergic pathways. This has implications beyond skin disease, potentially explaining why infections trigger or exacerbate allergic conditions throughout the body.
Questions still open
- Could therapeutic strategies that selectively block HBD2's mast cell-activating function while preserving antimicrobial activity improve allergic skin diseases?
- Is serum HBD2 measurement clinically useful for predicting angioedema risk in chronic urticaria patients?
Common questions
What are defensins?
Why would an antimicrobial peptide cause allergic problems?
Read the original research
Human β-defensin 2: a connection between infections and allergic skin diseases.
Acta dermatovenerologica Alpina, Pannonica, et Adriatica, 33(3), 135-139
Citation
Štrajtenberger, Maja; Stipić-Marković, Asja; Barac, Ema; Artuković, Marinko; Lugović-Mihić, Liborija. (2024). Human β-defensin 2: a connection between infections and allergic skin diseases.. Acta dermatovenerologica Alpina, Pannonica, et Adriatica, 33(3), 135-139.