Asthma and the metabolic syndrome may be more closely related than once believed. A short slide show summarizes key studies of known connections.
Asthma has been linked to markers of metabolic syndrome: Obesity, dyslipidemia, insulin resistance, and hypertension. Metabolic syndrome is linked to increased asthma severity. The systemic inflammation characteristic of metabolic syndrome could provide one explanation for these associations.(1)
Obesity may predispose to the development of asthma and complicate its control. Obese patients have more frequent asthma exacerbations than normal and overweight asthmatics.(1) Asthma associated with obesity is marked by neutrophilic airway inflammation, corticosteroid resistance, and increased morbidity.
Oxidative stress associated with obesity could cause functional changes of the airways and increase asthma severity. Proinflammatory mediators are elevated in obese asthma patients, and decrease after gastric bypass surgery.(1) Asthma control and lung function improves after weight loss.
Obese adipose tissue triggers the inflammatory cascade, leading to low-grade systemic inflammation. Obese asthmatics have abnormalities in proinflammatory mediators such as leptin, IL-6, TNF-Î±, C-reactive protein, and adiponectin.(1) Leptin levels have been linked to the development and severity of asthma regardless of BMI.(1) Leptin has been linked to increased systemic inflammation, even in non-obese patients.(1)
Dyslipidemia may influence the trafficking of immune cells to the lungs. Low serum levels of HDL have been associated with increased risk of asthma in adolescents.(2) High triglycerides and low HDL may be markers for inflammation and have been associated with wheezing in adults.(3) Asthmatics have increased levels of the most proinflammatory types of LDL (LDL-3 and LDL-4); LDL-3 has been linked to worse lung function.(4)
Insulin resistance is a strong, independent risk factor for the development of asthma.(5) Insulin and insulin-like growth factor are linked to lung development and function. Hyperinsulinemia may shift cells toward a TH2-type inflammatory response and directly affect lung functioning.
Thiazolidinediones: Activate PPAR-gamma receptors resulting in anti-inflammatory effects, and potentially reducing asthma exacerbations. Statins: Have anti-inflammatory properties; the role of lipoproteins in the development of asthma could suggest a role for statins in treating patients with asthma. Other agents that might help decrease airway inflammation: bisphosphonates, alendronate, retinoids. Similar effects could be obtained from diet and exercise.
The systemic inflammation characteristic of metabolic syndrome could provide one explanation for the link between asthma and metabolic syndrome. Obesity may predispose to the development of asthma and complicate its control. Dyslipidemia has been linked to increased risk of asthma, and may predispose to a proinflammatory state. Insulin resistance is a strong, independent risk factor for the development of asthma. Statins and thiazolidinediones may have anti-inflammatory effects that could be beneficial in asthma.
Metabolic abnormalities and deficits in lung function are often seen in the same individual and have historically been considered pathogenically distinct.Â Research is emerging that suggests mechanisms underlying each may underlie both.Key findings:âºâºÂ Metabolic syndrome (METS) is linked to increased asthma severityâºâº Asthma has been linked to markers of METS: Obesity, dyslipidemia, insulin resistance, hypertensionâºâº Obese adipose tissue triggers the inflammatory cascade, leading to low-grade systemic inflammation.âºâº Persons with asthma have increased levels of proinflammatory types of LDLMore in the slides above; references at bottom of page.
1. Serafino-Agrusa L, Spatafora M, Scichilone N. Asthma and the metabolic syndrome: current knowledge and future perspectives. World J Clin Cases. 2015;3:285-292. doi:10.12998/wjcc.v3.i3.285.
2. Yiallouros PK, Savva SC, Kolokotroni O, et al. Low serum high-density lipoprotein cholesterol in childhood is associated with adolescent asthma. Clin Exp Allergy. 2012;42:423-432. doi:10.1111/j.1365-2222.2011.03940.x.
3. Fenger RV1, Gonzalez-Quintela A, Linneberg A, et al. The relationship of serum triglycerides, serum HDL, and obesity to the risk of wheezing in 85,555 adults. Respir Med. 2013;107:816-824. doi:10.1016/j.rmed.2013.02.001. Epub 2013 Mar 5.
4. Scichilone N, Rizzo M, Benfante A, et al. Serum low density lipoprotein subclasses in asthma. Respir Med. 2013;107:1866-1872. doi:10.1016/j.rmed.2013.09.001. Epub 2013 Sep 14.
5. Singh S, Prakash YS, Linneberg A, et al. Insulin and the lung: connecting asthma and metabolic syndrome. J Allergy(Cairo). 2013;2013:627384. doi:10.1155/2013/627384. Epub 2013 Sep 24.