• 1 School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang, Malaysia
  • 2 School of Medical Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Malaysia
  • 3 School of Data Sciences, Perdana University, 43400 Serdang, Malaysia
  • 4 Community Health Center, Universiti Sains Malaysia, 11800 Penang, Malaysia
  • 5 Advanced Medical and Dental Institute, Universiti Sains Malaysia, 13200 Bertam, Malaysia
  • 6 Clinical Nutrition Intl (M) Sdn Bhd, 43200 Selangor, Malaysia
  • 7 Department of Biotechnology, Yeungnam University, 712-749 Gyeongsan, Korea. Electronic address:
  • 8 School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang, Malaysia. Electronic address:
J Dairy Sci, 2019 Jun;102(6):4783-4797.
PMID: 30954261 DOI: 10.3168/jds.2018-16103


The aims of this study were to investigate the effects of Lactobacillus plantarum DR7 isolated from bovine milk against upper respiratory tract infections (URTI) and elucidate the possible mechanisms underlying immunomodulatory properties. The DR7 strain (9 log cfu/d) was administered for 12 wk in a randomized, double-blind, and placebo-controlled human study involving 109 adults (DR7, n = 56; placebo, n = 53). Subjects were assessed for health conditions monthly via questionnaires, and blood samples were evaluated for cytokine concentrations, peroxidation and oxidative stress, and gene expression in T cells and natural killer (NK) cells. The administration of DR7 reduced the duration of nasal symptoms (mean difference 5.09 d; 95% CI: 0.42-9.75) and the frequency of URTI (mean difference 0.32; 95% CI: 0.01-0.63) after 12 and 4 wk, respectively, compared with the placebo. The DR7 treatment suppressed plasma proinflammatory cytokines (IFN-γ, TNF-α) in middle-aged adults (30 to 60 yr old), while enhancing anti-inflammatory cytokines (IL-4, IL-10) in young adults (<30 yr old), accompanied by reduced plasma peroxidation and oxidative stress levels compared with the placebo. Young adults who received DR7 showed higher expression of plasma CD44 and CD117 by 4.50- and 2.22-fold, respectively, compared with the placebo. Meanwhile, middle-aged adults showed lower expression of plasma CD4 and CD8 by 11.26- and 1.80-fold, respectively, compared with the placebo, indicating less T-cell activation. In contrast, both young and middle-aged adults who received DR7 showed enhanced presence of nonresting and mature NK cells compared with those who received the placebo. We postulate that DR7 alleviated the symptoms of URTI by improving inflammatory parameters and enhancing immunomodulatory properties.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.