Intestinal Lactobacillus sp. is associated with some cellular and metabolic characteristics of blood in elderly people

The higher counts or particular groups (Firmicutes/Bacteroidetes) of intestinal microbiota are related to host metabolic reactions, supporting a balance of human ecosystem. We further explored whether intestinal lactobacilli were associated with some principal cellular and metabolic markers of blood in 38 healthy >65-year-old persons. The questionnaire, routine clinical and laboratory data of blood indices as much as the oxidized low-density lipoprotein (ox-LDL) and baseline diene conjugates in low-density lipoprotein (BDC-LDL) of blood sera were explored. The PCR-based intestinal Lactobacillus sp. composition and counts of cultivable lactobacilli (LAB) were tested. The facultative heterofermentative lactobacilli (Lactobacillus casei and Lactobacillus paracasei) were the most frequent (89 and 97%, respectively) species found, while Lactobacillus acidophilus, Lactobacillus plantarum and Lactobacillus reuteri were present in almost half of the elderly persons. The number of species simultaneously colonizing the individuals ranged from 1 to 7 (median 4). In elderly consuming probiotics the LAB counts were significantly higher than in these not consuming (median 7.8, range 4.2–10.8 vs. median 6.3, range 3.3–9.7 log cfu/g; p = 0.005), adjusted (OR = 1.71, CI95 1.04–2.82; p = 0.035) for age and body mass index (BMI). The colonization by L. acidophilus was negatively related (r = ?0.367, p = 0.0275) to L. reuteri, staying significant after adjusting for age, sex and BMI (OR = 0.16, CI95 0.04–0.73; p = 0.018). However, the blood glucose concentration showed a tendency for a negative correlation for colonization with Lactobacillus fermentum (r = ?0.309, p = 0.062) adjusted for BMI (Adj. R² = 0.181; p = 0.013) but not for age and sex. The higher white blood cells (WBC) count was positively related (r = 0.434, p = 0.007) to presence of Lactobacillus reuteri adjusted for age, sex and BMI (Adj. R² = 0.193, p = 0.027). The lower values of ox-LDL were predicted by higher counts of cultivable lactobacilli adjusted by sex, age and BMI (r = ?0.389, p = 0.016; Adj. R² = 0.184 p = 0.029). In conclusion, the pilot study of elderly persons shows that the intestinal lactobacilli are tightly associated with WBC count, blood glucose and content of ox-LDL which all serve as risk markers in pathogenesis of inflammation, metabolic syndrome and cardiovascular disease (CVD).