Low ‘good’ cholesterol linked to higher risk of sarcoidosis: Study
Researchers note this could predict disease, provide target for therapies
Elevated blood levels of total blood cholesterol and low levels of high density lipoprotein cholesterol (HDL) — commonly called the “good” cholesterol — showed a significant correlation with sarcoidosis, according to a retrospective study conducted in China.
These findings suggest HDL and total blood cholesterol “could be regarded as predictors and may provide new diagnostic and therapeutic targets for sarcoidosis,” the researchers wrote in, “Blood glucose and lipids are associated with sarcoidosis: findings from observational and mendelian randomization studies,” which was published in the journal Respiratory Research.
Sarcoidosis is marked by clusters of inflammatory cells, called granulomas, in one or more organs, leading to damage. While the lungs and lymphatic system are most commonly affected, granulomas can appear anywhere in the body. The lymphatic system is a network of vessels and nodes that helps maintain fluid balance in the body and plays a crucial role in immune function.
While evidence suggests that blood sugar (glucose) and fat (lipid) levels are altered in sarcoidosis patients, whether there is a cause-and-effect relationship between these factors and disease risk remains unknown.
To answer this, researchers in China retrospectively analyzed data from 162 sarcoidosis patients followed at the Tongji hospital in China for 13 years, 2010-2023. People without sarcoidosis also were included and served as controls.
160 patients matched to controls
To ensure a fair comparison, the researchers used a technique called propensity score matching to match 160 patients with the same number of control participants for potential confounding factors, such as age and other disorders.
Most lesions in sarcoidosis patients were found in the chest lymph nodes (33.3%), bronchi and lungs (23.5%), and neck lymph nodes (13.6%). About 20.4% of patients had more than one positive lesion.
Statistical analyses were used to assess the association between sarcoidosis with blood fat levels, including HDL; low density lipoprotein cholesterol (LDL), also called “bad” cholesterol; total cholesterol; total triglyceride; and fasting glucose levels.
There was a significant correlation between sarcoidosis and low HDL levels and high total cholesterol when compared with controls. Specifically, higher total cholesterol levels were linked with a 3.9 times higher risk of sarcoidosis.
Low HDLC levels correlated significantly with bronchi and lung lesions and chest lymph nodes’ lesions, while this association was seen between neck lymph nodes’ lesions and total cholesterol.
Finally, the researchers used a method to test causality based on genetics, called Mendelian randomization or MR. The underlying principle of MR is that certain genetic variants have known links to certain traits, and so they can be used to assess the relationship between a risk factor and a particular outcome.
The researchers conducted a bidirectional MR analysis, meaning they assessed how genetic variants linked with sarcoidosis correlated with blood glucose and fat levels, and vice versa.
The results revealed high fasting glucose and high total cholesterol levels were associated with a higher risk of sarcoidosis, while higher levels of HDL predicted less occurrence of sarcoidosis.
These preliminary results suggest “the importance of blood glucose and lipids in the etiopathogenesis [cause and development] of sarcoidosis and can direct further researches about the basic mechanism and therapeutic value of blood glucose and lipids on sarcoidosis,” the study concluded.