Polysaccharides from discarded tobacco leaves modulate immunity and ameliorate intestinal injury in...

Discarded tobacco (Nicotiana tabacum) leaves are underutilized, resulting in environmental pollution and resource inefficiency. Previous research demonstrated the immunomodulatory potential of tobacco-derived oligosaccharides, but the effects of Nicotiana tabacum leaf polysaccharides (NTLP) on immunosuppression and intestinal damage remain unclear. This study explores NTLP's impact on immunomodulatory activity, intestinal barrier integrity, and gut microbiota regulation in cyclophosphamide (Cy)-treated mice.

Characterization of NTLP showed total sugar (743.1 ± 79.5 g kg^-1), uronic acid (112.5 ± 6.5 g kg^-1), and protein (9.1 ± 5.5 g kg^-1) contents, with molecular weights ranging from 5.362 to 1549 kDa. NTLP was composed of glucose, galactose, arabinose, galacturonic acid, glucuronic acid, rhamnose, and mannose in a molar ratio of 35.34:30.53:22.97:4.13:2.89:2.18:1.94. NTLP improved immune organ function by enhancing the thymus and spleen indices and increasing immunoglobulin and cytokine secretion in serum and spleen. Additionally, NTLP repaired intestinal mucosal injury and reduced intestinal permeability by upregulating secretory immunoglobulin (sIgA) and tight junction proteins (ZO-1 and claudin-1). Furthermore, NTLP significantly altered gut microbiota composition, increasing beneficial bacteria (e.g., Lactobacillus and Akkermansia) and decreasing pathogenic bacteria (e.g., Prevotella). Notably, the organ indices, immunoglobulin and cytokine secretion, and mRNA expression of tight junction proteins exhibited significant correlations with the abundance of gut microbiota under NTLP intervention.

NTLP can modulate gut microbiota composition, protect against intestinal mucosal injury, and enhance immune responses in Cy-treated mice, thereby providing a robust scientific basis for its application in immunological and gastrointestinal research. © 2025 Society of Chemical Industry.