Serum low density lipoprotein subclasses in asthma

Background: The levels of serum low-density lipoproteins (LDL) have been implicated in the inflammatory cascade in a murine model of asthma. Recent findings suggest that LDL may modulate the inflammatory state of the asthmatic airways in humans. Objective: We explored whether LDL subclasses are associated with the occurrence and severity of asthma. Methods: 24 asthmatics (M/F: 11/13) and 24 healthy individuals, with normal BMI and absence of metabolic syndrome, matched for age and gender. Serum concentrations of LDL subclasses were distributed as seven bands (LDL-1 and -2 defined as large, least pro-inflammatory LDL, and LDL-3 to 7 defined as small, most pro-inflammatory LDL), using the LipoPrintª System (Quantimetrix Corporation, Redondo Beach, CA, USA). Results: LDL-1 was similar in the two groups (56 ± 16% vs. 53 ± 11, p = NS), while LDL-2 was significantly lower in asthmatics as compared to controls (35 ± 8% vs. 43 ± 10%, p = 0.0074). LDL-3 levels were two-fold higher in the asthmatics, but the difference did not reach the statistical significance (8± 7.3% vs. 4±3%, p=NS). Smaller subclasses LDL-4 to LDL-7 were undetectable in controls. In asthmatics, LDL-1 was positively associated with VC% predicted (r=+0.572, pZ0.0035) and FEV1% predicted (r=+0.492, p=+.0146). LDL-3 was inversely correlated with both VC% predicted (r =-0.535, p =0.0071) and FEV1% predicted (r =-0.465, p = 0.0222). Conclusions: The findings of this pilot study suggest a role of LDL in asthma, and advocate for larger studies to confirm the association between asthma and dyslipidemia.