Lonicerae Japonicae Flos (LF) is a traditional Chinese medicine derived from the dried flower buds or newly unfurled blossoms of Lonicera japonica Thunb. It is commonly used to treat a variety of respiratory disorders. Prior pharmacological work has indicated that LF has anti-inflammatory effects in models of acute lung injury (ALI), but the mechanisms—particularly those involving the gut–lung axis and T cell subset regulation—are not fully defined.
The study aimed to investigate the mechanism by which LF extracts attenuate ALI, focusing on regulation of CD4+ T cell subsets (Th1/Th2/Th17/Treg) in both the lungs and colons of an LPS-induced ALI mouse model.
Male ICR mice were used to establish the ALI model by intraperitoneal administration of 10 mg/kg lipopolysaccharide (LPS). LF extracts were administered at three dose levels labeled low (LLF), medium (MLF) and high (HLF); dexamethasone (DEX) was included as a positive control. Specific dose quantities for LLF, MLF and HLF were not reported in the abstract.
Assessment occurred 24 hours after LPS induction. Primary experimental procedures included calculation of lung weight and lung index, histopathologic analysis of lung and colon tissue using hematoxylin and eosin (HE) staining, flow cytometric quantification of T cell proportions, qRT-PCR for relative mRNA expression, and protein detection by western blot, immunohistochemistry, and immunofluorescence.
Lung weight and lung index were measured as gross indicators of pulmonary edema and inflammation. Histopathologic scoring of lungs and colons evaluated tissue damage and inflammatory cell infiltration. Pro-inflammatory cytokine expression (TNF-α, IL-1β, IL-6) was measured at the mRNA and/or protein level. Tight-junction proteins in the colon (ZO-1 and occludin) were assessed to gauge epithelial barrier integrity. T cell subset distributions and signature cytokine levels were analyzed to determine effects on Th1/Th2/Th17/Treg balance.
Treatment with LF extracts and DEX reduced lung weight and lung index in ALI mice and lowered lung tissue damage and inflammation scores. LF extracts and DEX also diminished expression of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6) in lung tissue. In the colon, LF extracts and DEX inhibited tissue damage and reduced pro-inflammatory cytokine expression while increasing expression of epithelial tight-junction proteins ZO-1 and occludin, suggesting preservation or restoration of intestinal barrier function.
LF extracts modulated the characteristic cytokine expression profiles of Th1, Th2, Th17 and Treg cells in both lungs and colons. The extracts effectively restored the balance of Th1/Th2 and Th17/Treg subsets, which the authors associate with alleviation of tissue inflammation. Flow cytometry quantified shifts in CD4+ T cell subset proportions, while qRT-PCR and protein assays corroborated changes in lineage-specific cytokines and transcriptional regulators.
At the protein level, LF extracts significantly suppressed expression of Th1- and Th17-related transcription factors T-bet and RORγT, and increased expression of Th2- and Treg-related transcription factors GATA3 and Foxp3 in both lungs and colons. In addition, LF extracts inhibited activation of the CCR6/CCL20 signaling pathway in these tissues. The observed changes in transcription factor and chemokine/chemokine receptor signaling provide mechanistic links between LF treatment and rebalancing of CD4+ T cell subsets across the gut–lung axis.
In this LPS-induced ALI mouse model, LF extracts attenuated pulmonary injury, reduced lung and colon inflammation, and preserved colonic epithelial tight-junction proteins. These therapeutic effects were associated with modulation of CD4+ T cell subsets—restoring Th1/Th2 and Th17/Treg balance—and with suppression of the CCR6/CCL20 pathway in both lungs and colons. The authors conclude that the protective effects of LF in ALI involve immune rebalancing across the gut–lung axis.
Notes on limitations and reporting
The abstract reports experimental outcomes, methodologies and pathway associations but does not include specific numeric data, statistical values, or precise dosing details for LF groups within the abstract text. Detailed methods, full data, and dose regimens would need to be consulted in the full text.
Keywords: Acute lung injury; Lonicerae Japonicae Flos; Th1/Th2/Th17/Treg; CCR6/CCL20; Gut–lung axis; ZO-1; occludin.