Evaluation of the frequency of invariant natural killer T (iNKT) cells in nasal polyps

[Theories of the pathogenesis of polypous rhinosinusitis and the asthmatic triad]

Polypous rhinosinusitis (PRS) is a chronic inflammatory disease of the mucous membrane of the nasal cavity and paranasal sinuses, characterized by the formation and recurrent growth of polyps. Often, PRS is a manifestation of the most severe clinical symptom complex - the asthmatic triad (AT). AT is characterized by three main clinical manifestations: bronchial asthma (BA) itself, PRS, intolerance to acetylsalicylic acid, other nonsteroidal anti-inflammatory drugs (NSAIDs) and NA. However, not all three components of the triad are expressed equally, a variant of the dyad (BA with PRS) is possible. AT is one of the most severe variants of BA, it is more difficult to respond to conservative therapy and significantly reduces the ability of patients to work. In the world, PRS and AT are detected in 0.5-16% of the population, in Russia the number of patients is about 1.5 million people.

MATERIAL AND METHODS

The analysis of the medical literature on this problem has been carried out.

RESULTS

To date, there is no consensus on the etiology and pathogenesis of the polypous process in the nasal cavity and paranasal sinuses, therefore, many theories of the occurrence of this disease have been proposed, the main ones being: anatomical factors, osteitis, virological, bacterial, allergic, autoimmune theory and the theory of metabolic disorders of arachidonic acid. The key role in modern studies of the pathogenesis of AT is still given to the peculiarities of arachidonic acid metabolism.

CONCLUSIONS

The low effectiveness of treatment and the severity of clinical manifestations encourage scientists to further investigate the etiopathogenesis of polypous rhinosinusitis and the asthmatic triad.

Type 2 and Type 17 Invariant Natural Killer T Cells Contribute to Local Eosinophilic and Neutrophilic Inflammation and Their Function Is Regulated by Mucosal Microenvironment in Nasal Polyps

Chronic rhinosinusitis with nasal polyps (CRSwNP) is characterized by heterogeneous inflammatory endotypes of unknown etiology. Invariant natural killer T (iNKT) cells are multifunctional innate T cells that exhibit Th1-, Th2-, and Th17-like characteristics. We investigated functional relationships between iNKT cells and inflammatory subtypes of CRSwNP. Eighty patients with CRSwNP and thirty-two control subjects were recruited in this study. Flow cytometry was used to analyze the frequencies and functions of iNKT cells and their subsets in peripheral blood mononuclear cells (PBMCs) and tissues. Polyp tissue homogenates were used to study the multifunctionality of iNKT cells. iNKT cells were significantly increased in polyps (0.41%) than in control mucosa (0.12%). iNKT cells were determined in the paucigranunlocytic (n=20), eosinophilic (n=22), neutrophilic (n=23), and mixed granulocytic (n=13) phenotypes of CRSwNP. The percentages of iNKT cells and HLA-DR⁺PD-1⁺ subsets were lower in eosinophilic or mixed granulocytic polyps than those of other phenotypes. iNKT cells and subsets were enriched in polyp tissues than in matched PBMCs. The evaluation of surface markers, transcription factors, and signature cytokines indicated that the frequencies of iNKT2 and iNKT17 subsets were significantly increased in eosinophilic and neutrophilic polyps, respectively, than in the paucigranulocytic group. Moreover, the production of type 2 (partially dependent on IL-7) and type 17 (partially dependent on IL-23) iNKT cells could be stimulated by eosinophilic and neutrophilic homogenates, respectively. Our study revealed that type 2 and type 17 iNKT cells were involved in eosinophilic and neutrophilic inflammation, respectively, in CRSwNP, while different inflammatory microenvironments could modulate the functions of iNKT cells, suggesting a role of iNKT cells in feedback mechanisms and local inflammation.