The Versatile Gasdermin Family: Their Function and Roles in Diseases.

The gasdermin (GSDM) family, a novel group of structure-related proteins, consists of GSDMA, GSDMB, GSDMC, GSDMD, GSDME/DNFA5, and PVJK/GSDMF. GSDMs possess a C-terminal repressor domain, cytotoxic N-terminal domain, and flexible linker domain (except for GSDMF). The GSDM-NT domain can be cleaved and released to form large oligomeric pores in the membrane that facilitate pyroptosis. The emerging roles of GSDMs include the regulation of various physiological and pathological processes, such as cell differentiation, coagulation, inflammation, and tumorigenesis. Here, we introduce the basic structure, activation, and expression patterns of GSDMs, summarize their biological and pathological functions, and explore their regulatory mechanisms in health and disease. This review provides a reference for the development of GSDM-targeted drugs to treat various inflammatory and tissue damage-related conditions.

Association of inflammatory markers with hearing impairment: The English Longitudinal Study of Ageing.

BACKGROUND: Hearing impairment is common at an older age and has considerable social, health and economic implications. With an increase in the ageing population, there is a need to identify modifiable risk factors for hearing impairment. A shared aetiology with cardiovascular disease (CVD) has been advanced as CVD risk factors (e.g. obesity, type 2 diabetes) are associated with a greater risk of hearing impairment. Moreover, low-grade inflammation is implicated in the aetiology of CVD. Accordingly, our aim was to investigate the association between several markers of inflammation - C-reactive protein, fibrinogen and white blood cell count - and hearing impairment. METHODS: Participants of the English Longitudinal Study of Ageing aged 50-93 were included. Inflammatory marker data from both wave 4 (baseline, 2008/09) and wave 6 (2012/13) were averaged to measure systemic inflammation. Hearing acuity was measured with a simple handheld tone-producing device at follow-up (2014/15). RESULTS: Among 4879 participants with a median age of 63 years at baseline, 1878 (38.4%) people presented hearing impairment at follow-up. All three biomarkers were positively and linearly associated with hearing impairment independent of age and sex. After further adjustment for covariates, including cardiovascular risk factors (smoking, physical activity, obesity, diabetes, hypertension, cholesterol), memory and depression, only the association with white blood cell count remained significant: odds ratio per log-unit increase; 95% confidence interval = 1.46; 1.11, 1.93. CONCLUSIONS: While white blood cell count was positively associated with hearing impairment in older adults, no relationships were found for two other markers of low-grade inflammation.

BDNF, NT-3 and Trk receptor agonist monoclonal antibodies promote neuron survival, neurite extension, and synapse restoration in rat cochlea ex vivo models relevant for hidden hearing loss.

Neurotrophins and their mimetics are potential treatments for hearing disorders because of their trophic effects on spiral ganglion neurons (SGNs) whose connections to hair cells may be compromised in many forms of hearing loss. Studies in noise or ototoxin-exposed animals have shown that local delivery of NT-3 or BDNF has beneficial effects on SGNs and hearing. We evaluated several TrkB or TrkC monoclonal antibody agonists and small molecules, along with BDNF and NT-3, in rat cochlea ex vivo models. The TrkB agonists BDNF and a monoclonal antibody, M3, had the greatest effects on SGN survival, neurite outgrowth and branching. In organotypic cochlear explants, BDNF and M3 enhanced synapse formation between SGNs and inner hair cells and restored these connections after excitotoxin-induced synaptopathy. Loss of these synapses has recently been implicated in hidden hearing loss, a condition characterized by difficulty hearing speech in the presence of background noise. The unique profile of M3 revealed here warrants further investigation, and the broad activity profile of BDNF observed underpins its continued development as a hearing loss therapeutic.

Biomarkers of Systemic Inflammation and Risk of Incident Hearing Loss.

BACKGROUND: Chronic inflammation may lead to cochlear damage, and the only longitudinal study that examined biomarkers of systemic inflammation and risk of hearing loss found an association with a single biomarker in individuals <60 years of age. The purpose of our study was to determine whether plasma inflammatory markers are associated with incident hearing loss in two large prospective cohorts, Nurses' Health Studies (NHS) I and II. METHODS: We examined the independent associations between plasma levels of markers of systemic inflammation (C-reactive protein [CRP], interleukin-6 [IL-6], and soluble tumor necrosis factor receptor 2 [TNFR-2]) and self-reported hearing loss. The participants in NHS I (n = 6194 women) were 42 to 69 years of age at the start of the analysis in 1990, while the participants in NHS II (n = 2885 women) were 32 to 53 years in 1995. After excluding women with self-reported hearing loss before the time of blood-draw, incident cases of hearing loss were defined as those women who reported hearing loss on questionnaires administered in 2012 in NHS I and 2009 or 2013 in NHS II. The primary outcome was hearing loss that was reported as moderate or worse in severity, pooled across the NHS I and NHS II cohorts. We also examined the pooled multivariable-adjusted hazard ratios for mild or worse hearing loss. Cox proportional hazards regression was used to adjust for potential confounders. RESULTS: At baseline, women ranged from 42 to 69 years of age in NHS I and 32 to 53 years of age in NHS II. Among the NHS I and II women with measured plasma CRP, there were 628 incident cases of moderate or worse hearing loss during 100,277 person-years of follow-up. There was no significant association between the plasma levels of any of the three inflammatory markers and incident moderate or worse hearing loss (multivariable-adjusted pooled p trend for CRP = 0.33; p trend IL-6 = 0.54; p trend TNFR-2 = 0.70). There was also no significant relation between inflammatory marker levels and mild or worse hearing loss. While there was no significant effect modification by age for CRP or IL-6 in NHS I, there was a statistically significant higher risk of moderate or worse hearing loss (p interaction = 0.02) as well as mild or worse hearing loss (p interaction = 0.004) in women ≥60 years of age who had higher plasma TNFR-2 levels. CONCLUSIONS: Overall, there was no significant association between plasma markers of inflammation and risk of hearing loss.

Clinical and Molecular Phenotypes of Low-Penetrance Variants of NLRP3: Diagnostic and Therapeutic Challenges.

OBJECTIVE: Cryopyrin-associated periodic syndromes (CAPS) result from gain-of-function mutations in the NLRP3 gene, which causes excessive release of interleukin-1ß (IL-1ß) and systemic inflammation. While pathogenetic NLRP3 variant phenotypes are well-characterized, low-penetrance NLRP3 variants represent a significant clinical challenge. The aims of this study were to determine the clinical phenotype, the in vitro biologic phenotype, and the effect of anti-IL-1 treatment in patients with low-penetrance NLRP3 variants. METHODS: A multicenter study of consecutive symptomatic patients with low-penetrance NLRP3 variants recruited from 7 centers between May 2012 and May 2013 was performed. The observed findings were transferred into a study database, from which they were extracted for analysis. Controls were patients with a known pathogenetic NLRP3 variant. Clinical presentation and CAPS markers of inflammation were captured. Functional assays of inflammasome activation, including caspase 1 activity, NF-κB release, cell death, and IL-1ß release, were performed. Treatment effects of IL-1 were determined. Comparisons between low-penetrance and pathogenetic NLRP3 variants were performed. RESULTS: The study included 45 patients, 21 of which were female (47%); 26 of the patients (58%) were children. NLRP3 low-penetrance variants identified in the patients were Q703K (n = 19), R488K (n = 6), and V198M (n = 20). In the controls, 28 had pathogenetic NLRP3 variants. Patients with low-penetrance NLRP3 variants had significantly more fever (76%) and gastrointestinal symptoms (73%); eye disease, hearing loss, and renal involvement were less common. Functional inflammasome testing identified an intermediate phenotype in low-penetrance NLRP3 variants as compared to wild-type and pathogenetic NLRP3 variants. All treated patients responded to IL-1 inhibition, with complete response documented in 50% of patients. CONCLUSION: Patients with low-penetrance NLRP3 variants display a distinct clinical phenotype and an intermediate biologic phenotype, including IL-1ß and non-IL-1ß-mediated inflammatory pathway activation.

Biochemical, Cellular, Physiological, and Pathological Consequences of Human Loss of N-Glycolylneuraminic Acid.

About 2-3 million years ago, Alu-mediated deletion of a critical exon in the CMAH gene became fixed in the hominin lineage ancestral to humans, possibly through a stepwise process of selection by pathogen targeting of the CMAH product (the sialic acid Neu5Gc), followed by reproductive isolation through female anti-Neu5Gc antibodies. Loss of CMAH has occurred independently in some other lineages, but is functionally intact in Old World primates, including our closest relatives, the chimpanzee. Although the biophysical and biochemical ramifications of losing tens of millions of Neu5Gc hydroxy groups at most cell surfaces remains poorly understood, we do know that there are multiscale effects functionally relevant to both sides of the host-pathogen interface. Hominin CMAH loss might also contribute to understanding human evolution, at the time when our ancestors were starting to use stone tools, increasing their consumption of meat, and possibly hunting. Comparisons with chimpanzees within ethical and practical limitations have revealed some consequences of human CMAH loss, but more has been learned by using a mouse model with a human-like Cmah inactivation. For example, such mice can develop antibodies against Neu5Gc that could affect inflammatory processes like cancer progression in the face of Neu5Gc metabolic incorporation from red meats, display a hyper-reactive immune system, a human-like tendency for delayed wound healing, late-onset hearing loss, insulin resistance, susceptibility to muscular dystrophy pathologies, and increased sensitivity to multiple human-adapted pathogens involving sialic acids. Further studies in such mice could provide a model for other human-specific processes and pathologies involving sialic acid biology that have yet to be explored.

[Delayed diagnosis in a case of granulomatosis with polyangiitis (Wegener's) with initial predominance of joint involvement]. / Diagnostic tardiv într-un caz de granulomatoza cu poliangeita (Wegener) cu manifestari initiale articulare.

The authors present the case of a 53-year-old female, initially admitted in a rheumatology department for fever and diffuse arthritis--being diagnosed with sero-positive rheumathoid arthritis. Although the chest X-ray and CT scan of thorax showed several abnormal features (medium lobe atelectasis, pseudo-cyst in the posterior segment of the right upper lobe with satellite milliary nodules, mediastinal lymph node enlargement), the investigations performed in our pneumology department couldn't establish the etiology of radiological abnormalities. With non-steroidal antiinflamatory treatment, the patient got worse, being readmitted in our hospital after 3 months for high fever, diffuse arthralgia with functional impairment, small hemoptysis, loss of hearing and left ear ache and on chest X-ray with bilateral macronodules, some of these with cavitation. The investigations showed a slight alveolar hemorrhagic syndrome, positive cANCA antibodies, negative antiCCP antibodies--the diagnosis of Wegener's granulomatosis with lung and ENT involvement being established. Puls-therapy with Solumedrol and i.v. Cyclophosphamide was thereafter initiated with a favorable evolution. This case is special because of the initial misdiagnosis due to the atypical pulmonary manifestations and the non-specific paraclinical findings, in the context of diffuse arthritis with positive rheumatoid factor.

Higher prevalence of autoimmune diseases and longer spells of vertigo in patients affected with familial Ménière's disease: A clinical comparison of familial and sporadic Ménière's disease.

PURPOSE This study compared clinical features, predisposing factors, and concomitant diseases between sporadic and familial Ménière's disease (MD). METHOD Retrospective chart review and postal questionnaire were used. Participants were 250 definite patients with MD (sporadic, n =149; familial, n = 101) who fulfilled the American Academy of Otorhinolaryngology-Head and Neck Surgery (1995) criteria. RESULTS On average, familial patients were affected 5.6 years earlier than sporadic patients, and they suffered from significantly longer spells of vertigo (p = .007). The prevalence of rheumatoid arthritis (p = .002) and other autoimmune diseases (p = .046) was higher among the familial patients, who also had more migraine (p = .036) and hearing impairment (p = .002) in their families. CONCLUSION The clinical features of familial and sporadic MD are very similar in general, but some differences do exist. Familial MD patients are affected earlier and suffer from longer spells of vertigo.

Phosphorylation of the myosin IIA tailpiece regulates single myosin IIA molecule association with lytic granules to promote NK-cell cytotoxicity.

Natural killer (NK) cells are innate immune lymphocytes that provide critical defense against virally infected and transformed cells. NK-cell cytotoxicity requires the formation of an F-actin rich immunologic synapse (IS), as well as the polarization of perforin-containing lytic granules to the IS and secretion of their contents at the IS. It was reported previously that NK-cell cytotoxicity requires nonmuscle myosin IIA function and that granule-associated myosin IIA mediates the interaction of granules with F-actin at the IS. In the present study, we evaluate the nature of the association of myosin IIA with lytic granules. Using NK cells from patients with mutations in myosin IIA, we found that the nonhelical tailpiece is required for NK-cell cytotoxicity and for the phosphorylation of granule-associated myosin IIA. Ultra-resolution imaging techniques demonstrated that single myosin IIA molecules associate with NK-cell lytic granules via the nonhelical tailpiece. Phosphorylation of myosin IIA at residue serine 1943 (S1943) in the tailpiece is needed for this linkage. This defines a novel mechanism for myosin II function, in which myosin IIA can act as a single-molecule actin motor, claiming granules as cargo through tail-dependent phosphorylation for the execution of a pre-final step in human NK-cell cytotoxicity.

Expression of fractalkine receptor CX3CR1 on cochlear macrophages influences survival of hair cells following ototoxic injury.

The role of innate immunity and macrophage recruitment to the inner ear after hair cell injury is a subject where little is known. In this paper, we demonstrate recruitment of monocytes and macrophages to the inner ear after kanamycin. We also examined the effect of fractalkine receptor (CX3CR1) deletion in kanamycin ototoxicity. We observed more functional and structural damage in CX3CR1 null mice compared to wild-type and heterozygous littermates. In order to determine if increased susceptibility to kanamycin resulted from CX3CR1 deletion from cochlear leukocytes, we created bone marrow chimeras by transplanting CX3CR1-null bone marrow into wild-type mice whose native bone marrow was ablated by lethal irradiation. These mice were then treated with kanamycin sulfate. Auditory brainstem responses (ABR), hair cell counts, and numbers of macrophages recruited to the cochlea were recorded in irradiated mice that received either wild-type, CX3CR1 heterozygous, or CX3CR1 knockout bone marrow. A strong correlation was present between numbers of macrophages and hair cell death in recipients transplanted with CX3CR1 null marrow. No correlation between macrophage number and hair cell loss was present in mice transplanted with wild-type or CX3CR1 heterozygous marrow. We suggest that CX3CR1 plays a role in modulating the detrimental effects of cochlear macrophages after kanamycin ototoxicity. Our data point to the possibility that CX3CR1-deficient cochlear macrophages exacerbate kanamycin ototoxicity while CX3CR1-expressing monocytes do not.

Role for Toll-like receptor 2 in the immune response to Streptococcus pneumoniae infection in mouse otitis media.

Streptococcus pneumoniae is the most common pathogen associated with otitis media. To examine the role of Toll-like receptor 2 (TLR2) in host defense against Streptococcus pneumoniae infection in the middle ear, wild-type (WT; C57BL/6) and TLR2-deficient (TLR2(-/-)) mice were inoculated with Streptococcus pneumoniae (1 x 10(6) CFU) through the tympanic membrane. Nineteen of 37 TLR2(-/-) mice showed bacteremia and died within 3 days after the challenge, compared to only 4 of 32 WT mice that died. Of those that survived, more severe hearing loss in the TLR2(-/-) mice than in the WT mice was indicated by an elevation in auditory-evoked brain stem response thresholds at 3 or 7 days postinoculation. The histological pathology was characterized by effusion and tissue damage in the middle ear, and in the TLR2(-/-) mice, the outcome of infection became more severe at 7 days. At both 3 and 7 days postchallenge, the TLR2(-/-) mice had higher blood bacterial titers than the WT mice (P < 0.05), and typical bacteria were identified in the effusion from both ears of both mouse groups by acridine orange staining. Moreover, by 3 days postchallenge, the mRNA accumulation levels of NF-kappaB, tumor necrosis factor alpha, interleukin 1beta, MIP1alpha, Muc5ac, and Muc5b were significantly lower in the ears of TLR2(-/-) mice than in WT mice. In summary, TLR2(-/-) mice may produce relatively low levels of proinflammatory cytokines following pneumococcal challenge, thus hindering the clearance of bacteria from the middle ear and leading to sepsis and a high mortality rate. This study provides evidence that TLR2 is important in the molecular pathogenesis and host response to otitis media.

Role of proinflammatory cytokines in cisplatin-induced vestibular hair cell damage.

BACKGROUND: Cisplatin causes the impairment of inner ear functions, including hearing and balance, through the involvement of a number of mechanisms. However, no laboratory studies have been performed on involvement of inflammation-related events in cisplatin-mediated vestibular dysfunction. METHODS: We evaluated the secretion of proinflammatory cytokines and nuclear factor-kappaB (NF-kappaB) activation in cisplatin-treated UB/UE-1 utricular epithelial cells. We also employed immunohistochemistry to detect proinflammatory cytokines and NF-kappaB expression in cisplatin-injected mice. RESULTS: Productions of proinflammatory cytokines significantly caused the death of UB/UE1 cells by cisplatin. Pharmacologic inhibition of mitogen-activated protein (MAP) kinase/ERK kinase-1 (MEK1) or extracellular signal-regulated kinase (ERK) significantly attenuated the death of UB/UE1 cells caused by cisplatin and proinflammatory cytokines. Immunohistochemical studies revealed an increase in the expression of proinflammatory cytokines and NF-kappaB in both the cristae ampullae and utricle of cisplatin-injected mice. CONCLUSIONS: These results suggest that proinflammatory cytokines may play an important role in the pathogenesis of cisplatin-mediated vestibulo-toxicity.

Susac's syndrome: 1975-2005 microangiopathy/autoimmune endotheliopathy.

Susac's syndrome (SS) consists of the clinical triad of encephalopathy, branch retinal artery occlusions (BRAO) and hearing loss. It is due to a microangiopathy affecting the precapillary arterioles of the brain, retina, and inner ear (cochlea and semicircular canals). Women are more commonly affected than men (3:1); the age of onset ranges from 9 to 58 years; but young women between the ages of 20 and 40 are most vulnerable. The encephalopathy is almost always accompanied by headache which may be the presenting feature. Multifocal neurological signs and symptoms, psychiatric disturbances, cognitive changes, memory loss, and confusion may rapidly progress to dementia. The MRI shows a distinctive white matter disturbance that always affects the corpus callosum. The central callosal fibers are particularly vulnerable and central callosal holes develop as the active lesions resolve. Linear defects (spokes) and rather large round lesions (snowballs) sometime dominate the MRI findings, which include cortical, deep gray (70%) and leptomeningeal involvement (33%). Frequently, the lesions enhance and may be evident on diffusion weighted imaging (DWI). The BRAO are best evaluated with fluorescein angiography, which may show the pathognomonic multifocal fluorescence. Gass plaques are frequently present and reflect endothelial damage. Brain biopsy shows microinfarction to be the basic pathology, but more recent pathological studies have shown endothelial changes that are typical for an antiendothelial cell injury syndrome. Elevated levels of Factor VIII and von Willebrand Factor Antigen reflect the endothelial perturbation. Despite extensive evaluations, a procoagulant state has never been demonstrated. SS is an autoimmune endotheliopathy that requires treatment with immunosuppressants: steroids, cyclophosphamide, and intravenous immunoglobulin, usually in combination. Aspirin is a useful adjunct.

Cerebellar degeneration and hearing loss in a patient with idiopathic myenteric ganglionitis.

A 35-year-old male with an 11-year history of intestinal pseudo-obstruction associated with an idiopathic inflammatory insult of the myenteric plexus and the presence of circulating anti-Hu antibodies developed a neurological syndrome characterized by bilateral hearing loss, deteriorating balance, an unsteady gait and difficulty in estimating distances. A similar neurological syndrome has previously been described in older patients among the paraneoplasic syndromes associated with small-cell lung carcinoma and the presence of circulating anti-Hu antibodies, but never in the rare cancer-free patients with anti-Hu-associated chronic idiopathic intestinal pseudo-obstruction. The patient underwent a steroid treatment. No further episodes of functional intestinal obstruction were observed and, after an initial improvement, the neurological symptoms stabilized, leaving a permanent reduction in hearing function and an unsteady gait. The case shows that an idiopathic inflammatory insult of the myenteric plexus may precede (and perhaps lead to) central nervous system impairment in patients with anti-Hu-associated chronic idiopathic intestinal pseudo-obstruction.

Hipoacusia autoinmune / Autoimmune hearing loss

La Hipoacusia Autoinmune se manifiesta como una enfermedad rápidamente progresiva bilateral y es una de la pocas formas de Hipoacusia Neurosensorial que puede ser tratada medicamente. El proposito de este articulo es revisar la literatura que existe acerca de la Hipoacusia Autoinmune hasta la fecha, para entender mejor de la enfermedad

[The significance of genetic markers in otosclerotic hearing loss]. / Znachenie nekotorykh geneticheskikh markerov pri otoskleroticheskoi tugoukhosti.

Phenotypes HLA-A, HLA-B and HLA-C were determined in 85 patients with otosclerosis verified at surgery and in 113 clinically healthy subjects. The patients were divided into 2 groups: with family predisposition to otosclerosis (13 subjects) and without such (72 subjects). A tendency was established to more frequent occurrence of antigens A2, B12 versus less frequent of antigens B27, B40, Cw1 in patients compared to controls. It is concluded that at least one of the genes determining the resistance to otosclerosis exists in the HLA region, in binding groups B27, B40 and Cw1. It is suggested that genes predisposing to the disease (A2, B12) may be located at the same place.