The inflammation saga: Breakthrough nutritional insights for poultry

This symposium summary is scientifically valuable, well-organized, and provides a comprehensive overview of the nutritional and economic implications of intestinal health in poultry. The principal limitation is conceptual rather than experimental. Specifically, the review would benefit from a clearer distinction between physiological immune surveillance, adaptive homeostatic responses, and true intestinal inflammation. Throughout the manuscript, alterations in molecular biomarkers, microbial composition, epithelial barrier function, and immune activity are frequently interpreted as evidence of inflammation. However, current understanding suggests that these biological processes may also reflect normal physiological regulation or adaptive homeostatic responses, depending on their biological context. Incorporating this distinction would substantially improve the conceptual precision of the review while preserving its practical and translational relevance.

The definition of inflammation presented at the beginning of the manuscript is appropriate and consistent with the current understanding proposed by Medzhitov (2008), defining inflammation as an adaptive response to disrupted tissue homeostasis. However, this definition is not consistently maintained throughout the subsequent sections. As the discussion progresses, the interpretation gradually shifts toward a biomarker-based definition, in which changes in cytokine expression, endotoxin concentrations, tight junction proteins, microbial composition, or other molecular indicators are frequently treated as synonymous with inflammation. These parameters are undoubtedly valuable mechanistic indicators of biological activity, but they do not independently establish that the intestine has entered a true inflammatory state. Their interpretation should be integrated with evidence of tissue injury, loss of function, structural disruption, and coordinated inflammatory responses. Maintaining this distinction throughout the review would considerably strengthen its biological rigour.

A related issue concerns the interpretation of dysbiosis. In several instances, dysbiosis is presented as an almost inevitable precursor of intestinal inflammation. However, the relationship between microbial imbalance and inflammation is considerably more complex. Depending on its magnitude, duration, and biological consequences, dysbiosis may induce adaptive immune regulation, alter microbial metabolism, modify epithelial physiology, reduce ecosystem resilience, increase susceptibility to disease, or, under specific circumstances, trigger inflammatory responses. Thus, inflammation should be presented as one potential consequence of dysbiosis rather than its inevitable outcome. Recognizing this distinction would more accurately reflect current concepts of host–microbiota interactions and gastrointestinal ecology.
Similarly, the manuscript frequently implies a direct sequence linking barrier dysfunction to inflammation and subsequent performance loss. Although this progression is commonly observed in experimental disease models, alterations in epithelial barrier integrity may also occur during physiological adaptation, epithelial renewal, nutritional or metabolic adjustments, or transient tissue remodelling without fulfilling the pathological criteria for inflammation. Consequently, changes in barrier function should be interpreted within their biological context rather than considered independent evidence of inflammatory disease.

This contextual interpretation also applies to the use of molecular biomarkers. Throughout the review, variables such as endotoxin concentrations, cytokine profiles, tight junction protein expression, and other inflammatory markers are frequently used as surrogates for intestinal inflammation. While these biomarkers provide essential mechanistic information, they quantify biological activity rather than define the biological state itself. Emphasizing this distinction would improve the interpretation of experimental findings and reduce the risk of overestimating inflammatory responses based solely on molecular observations.

From a physiological perspective, the manuscript also tends to present immune activation primarily as an energetic cost that compromises growth performance. Although excessive or pathological inflammatory responses undoubtedly impose substantial metabolic demands, the healthy intestine continuously invests energy in epithelial renewal, mucus production, antimicrobial peptide synthesis, secretory IgA production, immune surveillance, vascular regulation, and maintenance of barrier integrity. These constitutive activities represent essential components of gastrointestinal homeostasis rather than inflammatory costs. Distinguishing the normal physiological maintenance requirements of the gastrointestinal ecosystem from the additional energetic costs associated with true inflammatory responses would provide a more balanced biological perspective.

Another conceptual aspect that deserves greater attention is the biological endpoint of inflammation. The discussion focuses primarily on inflammatory initiation, performance losses, antibiotic growth promoters, and nutritional alternatives, yet provides little consideration of the processes that complete the inflammatory response. Contemporary inflammation biology recognizes resolution, tissue repair, structural remodelling, and functional restoration as integral phases of the inflammatory response. Including these processes would provide a more complete biological framework and reinforce the idea that the objective of inflammation extends beyond controlling injurious stimuli to restoring normal gastrointestinal function.

Finally, the discussion of antibiotic growth promoters (AGPs) would benefit from a more nuanced interpretation. The manuscript frequently attributes its benefits to reduced inflammation. However, AGPs may improve animal performance through multiple complementary mechanisms, including reducing pathogen burden, stabilizing microbial ecology, improving epithelial barrier function, decreasing inflammatory stimuli, altering microbial metabolism, and modulating immune signalling pathways. Consequently, their beneficial effects may derive as much from preserving gastrointestinal homeostasis as from directly attenuating inflammatory responses. Recognizing this broader interpretation would better reflect the multifactorial nature of AGP activity and align the discussion with contemporary concepts of intestinal ecosystem function.

Overall, these suggestions do not challenge the scientific merit of the symposium summary. Rather, they are intended to strengthen its conceptual framework by distinguishing physiological regulation from pathological inflammation and by emphasizing the importance of biological context when interpreting immune activation, microbial alterations, epithelial responses, and molecular biomarkers. Such refinements would further enhance the scientific rigour and long-term impact of this otherwise valuable review.