Neutrophil-mediated immune response as a possible mechanism of acute unilateral vestibulopathy.

OBJECTIVE: This study aimed to investigate the underlying pathogenesis of acute unilateral vestibulopathy (AUV) using gene expression profiling combined with bioinformatics analysis. METHODS: Total RNA was extracted from the peripheral blood mononuclear cells of ten AUV patients in the acute phase and from ten controls. The differentially expressed genes (DEGs) between these two groups were screened using microarray analysis with the cut-off criteria (|fold changes| > 1.5 and p-value < 0.05). Functional enrichment analysis of DEGs was performed using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis, and the protein-protein interaction (PPI) network was constructed using the STRING (Search Tool for the Retrieval of Interacting Genes) database. RESULTS: There were 57 DEGs (50 up-regulated and 7 down-regulated) identified in the AUV group. Functional enrichment analysis showed that most of the up-regulated DEGs were significantly enriched in terms related to the neutrophil-mediated immune pathway. From the PPI network, the top ten hub genes were extracted by calculating four topological properties, and most of them were related to the innate immune system, inflammatory processes and vascular disorders. The complete blood count tests showed that the neutrophil-to-lymphocyte ratio was significantly higher in the 72 AUV patients than in the age-matched controls (2.93±2.25 vs 1.54±0.61, p < 0.001). CONCLUSIONS: This study showed that the neutrophil-mediated immune pathway may contribute to the development of AUV by mediating inflammatory and thrombotic changes in the vestibular organ.

Proinflammatory activation of peripheral blood mononuclear cells in patients with vestibular neuritis.

Vestibular neuritis (VN) is characterized by acute vertigo with spontaneous nystagmus and is often accompanied by vegetative symptoms. While the pathogenetic process leading to this disease is widely unknown, increasing evidence exists that a proinflammatory environment is responsible for the induction and progression of VN. Twelve patients with acute VN and 12 healthy, age-matched individuals were included in this study. In addition to routine blood parameters, plasma levels of soluble CD40 receptor/ligand (sCD40/sCD40L) were determined by ELISA. Moreover, peripheral blood mononuclear cells (PBMCs) were isolated by Ficoll density gradient. Afterwards, in CD14 (monocytes), CD68 (macrophages), CD3 (T lymphocytes) or CD19 (B lymphocytes) subpopulations, proinflammatory [CD40, tumor necrosis factor-α (TNF-α), and COX-2], proapoptotic [caspase-3, and poly(adenosine diphosphate ribose) polymerase] and proadhesive (CD38) proteins were measured by 2-color fluorescence-activated cell sorter analyses. In comparison to healthy individuals, patients with acute VN revealed significantly elevated plasma levels of C-reactive protein, whereas plasma levels of sCD40 and sCD40L, as well as cholesterol/triglyceride status were similar. However, we found a significant elevation of the percentage of proinflammatory CD40+, TNF-α+, COX-2+ or CD38+ PBMCs. Elevation of proinflammatory and proadhesive proteins in PBMCs of patients with acute VN in parallel with an acute phase response may contribute to disease induction and progression and, thus, may be suggested as a novel therapeutic target.

[Lyme disease--a reason for sudden sensorineural hearing loss and vestibular neuronitis?]. / Die Lyme-Borreliose--eine Ursache für "Hörsturz" und "Vestibularisausfall"?

BACKGROUND: Lyme disease has been described as one possible cause of sudden sensorineural hearing loss and vestibular neuronitis. The necessity of serological diagnosis and its therapeutic consequences have been discussed controversially. PATIENTS AND METHODS: 344 patients with acute sensorineural hearing loss and 66 patients with vestibular neuronitis were examined in retrospect. By means of ELISA (Enzygnost Borreliosis, Dade Behring Marburg) the specific prevalences of IgG- and IgM-antibodies against borrelia in serum were evaluated. The frequency of seroprevalences for both diseases were compared to those given in the literature. Neurootological findings of the seropositive patients were compared with those of seronegative and analysed statistically. RESULTS: 15.7 % of the patients with sudden sensorineural hearing loss had positive levels of IgG-antibodies. IgM-titers were elevated in 4.7 % of the patients. The seroprevalences for IgM and IgG were above those described by other investigators for the healthy population. Patients with positive IgM-antibodies showed more often low frequency hearing loss than IgG-positive patients. 18.2 % of the patients with neuronitis vestibularis had IgG- and 1.5 % IgM-antibodies against Borrelia. Whereas IgG occurred more often than known for the healthy population, IgM was within the limit for the healthy population. The seropositive group did not show any remarkable neurootological signs compared with the seronegative group. CONCLUSIONS: Because of the elevated seroprevalences Borrelia infections may be one possible but very rare cause of sudden sensorineural hearing loss and vestibular neuronitis. Low frequency hearing loss may be a sign for an infection with Borrelia as an etiological factor especially in combination with seropositive titers. In case of the presence of IgM-antibodies, patients may be treated with oral antibiotics (Doxycyclin, Cefuroxim). In patients with neuronitis vestibularis a neuroborreliosis should be excluded by means of lumbar puncture.

Use of mammalian inner ear antigens for the diagnosis of autoimmune sudden loss of vestibular function.

It has been postulated that bilateral sensorineural hearing loss (SNHL) may be the result of an ongoing autoimmune process against the inner ear and a pattern of progressive bilateral SNHL linked to an autoimmune inner ear disorder has been reported. Various attempts have been made to develop an assay to confirm the diagnosis of autoimmune inner ear disease. In this study we used a Western blot assay to determine the presence of IgG antibodies directed against a PO antigen (30 kDa) of the guinea pig in the sera of patients affected by sudden loss of vestibular function (SLVF). Ten patients affected by vestibular neuritis were enrolled: eight with unilateral vestibular loss and two with sequential bilateral impairment. We also tested nine patients with sudden unilateral hearing loss, five with benign paroxysmal positional vertigo and six normal subjects. In the present study only one patient, a woman affected by bilateral vestibular impairment, had IgG antibodies against the PO protein. Our results indicate either that the antigen PO is not a valid marker for autoimmune unilateral SLVF or that our patients did not have an immunological basis for their disease. However, we can suggest that bilateral impairment of vestibular function and bilateral progressive SNHL are more likely to be immune-mediated disorders and that PO could be a valid marker for these diseases. As bilateral vestibular neuritis is an uncommon disease, a multicentre study is required to confirm our suggestions.