Defence of doctoral thesis on isolated postnasal drip syndrome

On 11 January 2018 at 15:00 in an open meeting of Rīga Stradiņš University (RSU) Medical Promotion Council to be held in the Hippocrates Lecture Theatre (16 Dzirciema Street, Riga) Gunta Sumeraga will defend her doctoral thesis “The role of neuropeptides and neurogenic inflammation in the isolated postnasal drip syndrome”.

The nasopharyngeal mucus commonly is a manifestation of some disease. The postnasal drip is a frequent symptom of acute or chronic sinusitis, allergic rhinosinusopathy or the gastroesophageal reflux disease. Following proper treatment, postnasal drip normally disappears. Nevertheless, there are patients with postnasal drip and with no other symptoms or signs of any other disorders listed previously. The mucus, although not life threatening, affects the quality of life, causing irritation in nasopharynx, foreign body sensation in the throat and dry cough, provoking the willingness to get rid of the mucus. In scientific literature, this condition is referred as the isolated postnasal drip syndrome. The etiology and pathogenesis of the syndrome are still unclear and make the development of an effective treatment method rather cumbersome.

The purpose of the doctoral thesis was to undergo an in-depth examination of the nasal and nasopharyngeal mucosa processes in case of isolated postnasal drip syndrome. The study involved 20 patients with isolated postnasal drip syndrome and a control group consisting of 20 individuals without any symptoms of postnasal drip. The biopsies of nasal and nasopharyngeal mucosa were taken from all individuals involved in the study.

In order to identify any changes in the innervation of nasal mucosa, the author of the thesis used general markers (PGP 9.5 and chromogranin A) likewise specific markers of sympathetic (NPY) parasympathetic (VIP) and sensory (Substance P, CGRP) activity. A special marker – caspases was used for apoptosis assessment, whereas to identify tissue remodelling processes in case of inflammation, the distribution of matrix metalloproteinase, type IV collagen, fibronectin and laminin in nasal and nasopharyngeal mucosal tissues were determined. Beta defensin – a naturally occurring antimicrobial peptide and the nuclear factor-kappa beta (NFκβ) which participates in regulating gland secretion, were also tested. To localize the inflammation of mucosal tissues, Interleukin-6 and Interleukin-10 were determined.

The study revealed that a pronounced chronic inflammation of nasal and particularly nasopharyngeal mucosa with tissue remodelling processes was seen in patients with isolated postnasal drip syndrome, whereas the statistically significant highest amount of caspase-containing cells proved apoptosis activation in circumstances of explicit tissue remodelling. The identification of increased presence of pro-inflammatory cytokine (Il-6) and anti-inflammatory response cytokine (Il-10) in the nasal and nasopharyngeal mucosa of patients with isolated postnasal drip syndrome, suggests a relative balance of inflammatory and anti-inflammatory processes, whereas the detection of elevated levels of β-defensin and NFκβ immunopositive cells in nasal and nasopharyngeal mucosa, bear evidence on active local secretion of mucous glands in case of isolated postnasal drip syndrome.

The study allows more precise definition of the etiology and pathogenesis of the isolated postnasal drip syndrome and points towards nasopharyngeal mucosa as the possible primary localization of the isolated postnasal drip syndrome.