Vitamin D and Streptococci: The Interface of Nutrition, Host Immune Response, and Antimicrobial Activity in Response to Infection

Abstract

Streptococcus species are common causes of human infection. These Gram-positive, encapsulated bacterial pathogens infect diverse anatomic spaces, leading to infections including skin and soft tissue infection, endocarditis, pneumonia, meningitis, sinusitis, otitis media, chorioamnionitis, sepsis, and even death. Risk for streptococcal infection is highest in low- and middle-income countries where micronutrient deficiency is common. Epidemiological data reveal that vitamin D deficiency is associated with enhanced risk of streptococcal infection and cognate disease outcomes. Additionally, vitamin D improves antibacterial defenses by stimulating innate immune processes such as phagocytosis and enhancing production of reactive oxygen species (oxidative burst) and antimicrobial peptides (including cathelicidin and lactoferrin), which are important for efficient killing of bacteria. This review presents the most recent published work that studies interactions between the micronutrient vitamin D, the host immune system, and pathogenic streptococci as well as comparisons with other relevant infection models.

Vitamin D Levels Are Reduced at the Time of Hospital Admission in Sicilian SARS-CoV-2-Positive Patients

“…Many studies investigating the effects of vitamin D on viral infections featured enveloped viruses. The antiviral effects of cathelicidin, in the form of LL-37, may be partially mediated by envelope disruption, as it mediates the disruption of bacterial membranes [5,[18][19][20]. Furthermore, vitamin D has a role in the maintenance of many cellular junctions that act as physical barriers to pathogens [15].…”

The Role of Vitamin D in Neurodegeneration and Other Pathological Processes of the Central Nervous System

“…As Guevara et al and Golpour et al pointed out in their overviews, [41,42]. VD exerts a wide range of effects on the very pathomechanisms implicated in brain infection.…”

“…VD exerts a wide range of effects on the very pathomechanisms implicated in brain infection. The targets of these actions can be both host cells by enhancing innate immunomodulatory activity as well as pathogen cells by displaying direct antibacterial and antimicrobial properties [41,42]. The authors elucidate that VD, which is signaling through the VDR, stimulates innate immune cell functions, including phagocytosis, production of antimicrobial peptides (AMPs), and reactive oxygen species (ROS).…”

“…The authors elucidate that VD, which is signaling through the VDR, stimulates innate immune cell functions, including phagocytosis, production of antimicrobial peptides (AMPs), and reactive oxygen species (ROS). It is also responsible for upregulation of the pattern recognition receptors (PRR) TLR2 and NOD2 and generation of TIMP-1, which downregulates matrix metalloproteinases (MMPs) [41]. Furthermore, VD inhibits the production of MMPs and proinflammatory cytokines.…”

“…Furthermore, VD inhibits the production of MMPs and proinflammatory cytokines. VD also deranges Th17 programming, which instead leads to the promotion of the regulatory T cell phenotype [41]. But, VD also directly impedes the growth, viability, and biofilm formation of various bacteria [41][42][43].…”