Smell and autoimmunity: a comprehensive review

Effect of the rs2821557 Polymorphism of the Human Kv1.3 Gene on Olfactory Function and BMI in Different Age Groups

The sense of smell plays an important role in influencing the eating habits of individuals and consequently, their body weight, and its impairment has been associated with modified eating behaviors and malnutrition problems. The inter-individual variability of olfactory function depends on several factors, including genetic and physiological ones. In this study, we evaluated the role of the Kv1.3 channel genotype and age, as well as their mutual relationships, on the olfactory function and BMI of individuals divided into young, adult and elderly groups. We assessed olfactory performance in 112 healthy individuals (young n = 39, adult n = 36, elderly n = 37) based on their TDI olfactory score obtained through the Sniffin' Sticks test and their BMI. Participants were genotyped for the rs2821557 polymorphism of the human gene encoding Kv1.3 channels, the minor C allele of which was associated with a decreased sense of smell and higher BMIs compared to the major T allele. The results show that TT homozygous subjects obtained higher TDI olfactory scores and showed lower BMIs than CC homozygous subjects, in all age groups considered. Furthermore, the positive effect of the T allele on olfactory function and BMI decreased with increasing age. The contribution of the genetic factor is less evident with advancing age, while the importance of the age factor is compensated for by genetics. These results show that genetic and physiological factors such as age act to balance each other.

Autoantibody profiles assessment in individuals with persistent olfactory impairment following SARS-CoV-2 infection

BACKGROUND

Olfactory impairment, particularly hyposmia and anosmia, has emerged as a distinctive early symptom of SARS-CoV-2. Drawing on the historical association of autoimmune diseases with olfactory function, this study delves into the connections between COVID-19, autoimmunity, and persistent olfactory dysfunctions, focusing on individuals experiencing long-lasting smell disorders (3-18 months post-SARS-CoV-2 infection).

METHODS

The study comprised 36 Long Covid patients with persistent olfactory dysfunctions, alongside two control groups. Olfactory functionality was assessed using the Sniffin' Sticks extended test. Non-invasive olfactory mucosa brushing and nasal secretions were processed for nasal samples, while serum samples were obtained through peripheral venous sampling. A panel of autoantibodies, including Immunocirculating Complexes, ANA, ENA, and AECA, was investigated in serum and brush supernatant samples.

RESULTS

Contrary to expectations, the absence of traditional autoantibodies challenges the proposed autoimmune etiology of Long Covid-associated olfactory dysfunction. However, the presence and potential pathogenic role of AECA suggest viral cytopathic and inflammatory involvement in specific anatomical districts. One hypothesis explores the impact of inflammation and cytokine release induced by the viral infection, altering neuronal signaling and contributing to persistent hyposmia.

CONCLUSION

This research contributes to our understanding of the complex relationships between autoimmunity, olfactory impairment, and COVID-19. The absence of classical autoantibodies challenges prevailing theories, while the prominence of AECA hints at unique viral-induced pathogenic mechanisms. By unraveling these complexities, this study enhances our comprehension of post-acute sequelae, offering valuable perspectives on immune-mediated responses in the aftermath of the pandemic.

Increased risk of olfactory and taste dysfunction in the United States psoriasis population

BACKGROUND

It is plausible that immunopathological processes associated with psoriasis might contribute to the occurrence of olfactory or taste dysfunction. However, the actual association was still unknown.

PURPOSE

To determine the relationship between olfactory or taste dysfunction and psoriasis.

METHODS

Two cross-sectional studies were performed by using National Health and Nutrition Examination Survey (NHANES) data. Participants with psoriasis were defined as cases and those without psoriasis were identified as controls. Taste and smell self-reported questionnaires were used to define smell/taste alterations and identification tests were used to assure the smell/taste dysfunctions. Logistic regression models with inverse probability treatment weighting (IPTW) strategies were conducted to investigated the relationship between psoriasis and olfactory or taste dysfunction.

RESULTS

Self-reported questionnaires indicated that psoriasis patients were more likely to have perceived taste alteration (IPTW-aOR = 1.43) and smell alteration (IPTW-aOR = 1.22). Identification tests revealed that psoriasis was associated with taste dysfunction (IPTW-aOR = 1.28) and olfactory dysfunction (IPTW-aOR = 1.22). Relevant findings showed that psoriasis may be significantly associated with taste or olfactory dysfunction regardless of the questionnaire data or identification examination data used.

CONCLUSION

Olfactory and taste dysfunction could be considered comorbidities in patients with psoriasis based on our observational study. Therefore, physicians should be cautious of olfaction and taste alterations among patients with psoriasis.

Smell and Taste Function and Their Disturbances in Sjögren's Syndrome

Chemosensory disorders are a possible disturbance in Sjögren's syndrome (SS). The aim of the study is to comprehensively present chemosensory disorders in SS and to indicate their possible causes. The possible causes of taste and smell disorders in SS are changes in the structure of exocrine glands and their dysfunction, damage to receptors and weakening of their ability to regenerate, and neurological changes in the form of peripheral neuropathy and impaired cognitive function. Other postulated causes of chemosensory disorders are autoimmune mechanisms, adverse effects of drugs used in SS, and primary potentially SS-triggering viral infections. They are multifactorial and may occur independently of each other. The time of their onset and correlation with other disease symptoms may facilitate the determination of their primary cause in each patient. Awareness of chemosensory disorders in SS may help to ease their progress and eliminate other factors responsible for their more severe manifestation. In the prevention and treatment of chemosensory disorders in SS, the most important thing is to alleviate xerostomia and dryness in the nasal cavity and their effects in the form of chronic local inflammations, counteract receptor atrophy, and an implementation of appropriate neurological diagnosis and treatment.

COVID-19 and Autoimmune Liver Diseases

SARS-CoV-2 infection can trigger autoimmune responses, either by a systemic hyperstimulation of the immune system or molecular mimicry (or both). We here summarize the current knowledges about autoimmune liver diseases (AILDs) and COVID-19, focusing on (a) the risk of SARS-CoV-2 infection in patients affected by AILDs and/or under pharmacological treatment with immunosuppressants; (b) the capability of vaccination against SARS-CoV-2 to trigger autoimmune responses in the liver; and (c) the efficacy of vaccines against SARS-CoV-2 in patients with AILDs. Although unconclusive results have been obtained regarding the risk of being infected by SARS-CoV-2, generally indicating that all patients with chronic liver diseases have the same risk, irrespective of the etiology, the use of immunosuppressants in patients with AILDs seems to be correlated to COVID-19 severity. Few cases of autoimmune hepatitis (AIH) after SARS-CoV-2 vaccination have been reported, all characterized by a complete remission upon steroid treatment, but further evidence is needed to demonstrate the causality assessment. Humoral responses have been observed in patients with AILDs upon vaccination. In conclusion, the link between SARS-CoV-2 infection and AILDs is far to be completely elucidated. In these patients, the use of immunosuppressants has been correlated to an increase of disease severity and lower levels of antibodies upon vaccination.

International consensus statement on allergy and rhinology: Olfaction

BACKGROUND

The literature regarding clinical olfaction, olfactory loss, and olfactory dysfunction has expanded rapidly over the past two decades, with an exponential rise in the past year. There is substantial variability in the quality of this literature and a need to consolidate and critically review the evidence. It is with that aim that we have gathered experts from around the world to produce this International Consensus on Allergy and Rhinology: Olfaction (ICAR:O).

METHODS

Using previously described methodology, specific topics were developed relating to olfaction. Each topic was assigned a literature review, evidence-based review, or evidence-based review with recommendations format as dictated by available evidence and scope within the ICAR:O document. Following iterative reviews of each topic, the ICAR:O document was integrated and reviewed by all authors for final consensus.

RESULTS

The ICAR:O document reviews nearly 100 separate topics within the realm of olfaction, including diagnosis, epidemiology, disease burden, diagnosis, testing, etiology, treatment, and associated pathologies.

CONCLUSION

This critical review of the existing clinical olfaction literature provides much needed insight and clarity into the evaluation, diagnosis, and treatment of patients with olfactory dysfunction, while also clearly delineating gaps in our knowledge and evidence base that we should investigate further.

Therapeutic diminution of Interleukin-10 with intranasal theophylline administration in hyposmic patients

OBJECTIVE

To determine changes in nasal mucus Interleukin-10 (IL-10) before and after intranasal theophylline treatment in hyposmic patients, and the relationship of these changes to orally administered theophylline treatment.

DESIGN

IL-10 was measured in nasal mucus samples of 17 normal subjects and 39 patients with hyposmia of multiple etiologies by use of a sensitive spectrophotometric ELISA assay. Hyposmia is defined clinically by standardized evaluation of impaired olfactometry, as well as subjectively self reported by the patient.

RESULTS

Prior to treatment, IL-10 levels in nasal mucus were increased in hyposmic patients compared to controls. Following intranasal theophylline administration, over half of treated patients experienced a decrease of nasal mucus IL-10 toward control levels, correlated with a significant improvement in taste and smell function. Patients who increased with intranasal administration, similar to previously reported oral administration, showed no significant improvement in taste or smell function.

CONCLUSIONS

Nasal mucus IL-10 decreased in patients treated with intranasal theophylline. Mechanisms of action include phosphodiesterase and nuclear factor kappa-B inhibition, correlated with an improvement in both olfaction and gustation. IL-10 is induced by therapeutic and systemic administration of theophylline as with oral dosage, but reduced by lower and localized treatment.

Olfactory dysfunction in primary Sjogren's syndrome and its correlation with dry eye

Objective

To evaluate the olfactory function in primary Sjögren’s syndrome (pSS) patients and investigate its correlation with dry eye parameters.

Methods

Thirty-eight pSS patients (49.47 ± 10.06 years) and 20 healthy volunteers (47.40 ± 8.92 years) were enrolled in the study. All participants underwent ENT and eye examinations including a modified Connecticut Chemosensory Clinical Research Center (CCCRC) test, tear break-up time (TBUT), ocular surface staining (OSS) and Schirmer test. The parameters were compared between the two groups using Student-t test, and Pearson test was used to evaluate the correlations.

Results

Mean Schirmer and TBUT values were 2.39 ± 1.48 mm/5 min and 3.66 ± 1.5 sec in pSS and 18.30 ± 6.16 mm/5 min and 14.60 ± 3.64 sec in healthy subjects (p < 0.001, both). There was a significant decrease in mean odour threshold, odour identification, CCCRC and VAS scores in the pSS group (p < 0.001). Dry eye parameters showed moderate correlations with CCCRC parameters (r = 0.4-0.6, p < 0.001) and olfaction VAS score (r = 0.4-0.75, p < 0.05).

Conclusions

There is a mild clinical impairment in smell sense in patients with pSS which seems to be correlated with dry eye parameters. Therefore, smell complaints should be queried in pSS patients suffering from severe dry eye.

MOSES: A New Approach to Integrate Interactome Topology and Functional Features for Disease Gene Prediction

Disease gene prediction is to date one of the main computational challenges of precision medicine. It is still uncertain if disease genes have unique functional properties that distinguish them from other non-disease genes or, from a network perspective, if they are located randomly in the interactome or show specific patterns in the network topology. In this study, we propose a new method for disease gene prediction based on the use of biological knowledge-bases (gene-disease associations, genes functional annotations, etc.) and interactome network topology. The proposed algorithm called MOSES is based on the definition of two somewhat opposing sets of genes both disease-specific from different perspectives: warm seeds (i.e., disease genes obtained from databases) and cold seeds (genes far from the disease genes on the interactome and not involved in their biological functions). The application of MOSES to a set of 40 diseases showed that the suggested putative disease genes are significantly enriched in their reference disease. Reassuringly, known and predicted disease genes together, tend to form a connected network module on the human interactome, mitigating the scattered distribution of disease genes which is probably due to both the paucity of disease-gene associations and the incompleteness of the interactome.

Age-Related Olfactory Decline Is Associated With Levels of Exercise and Non-exercise Physical Activities

Objective: This cross-sectional study evaluates the impact of active or non-active lifestyle in terms of physical, cognitive and social activity on the olfactory function in Elderly Subjects (ES) and aims at looking for a correlation between the time devoted to life activities and the score obtained during the olfactory tests by each individual.

Methods: One hundred and twenty-two elderly volunteers were recruited in Sardinia (Italy) and divided into active ES (n = 60; 17 men, 43 women; age 67.8 ± 1.12 years) and inactive ES (n = 62; 21 men, 41 women, age 71.1 ± 1.14 years) based on their daily physical activities. The olfactory function was evaluated using the “Sniffin’s Sticks” battery test, while the assessment of daily activities was made by means of personal interviews.

Results: A significant effect of active or inactive lifestyle was found on the olfactory function of ES (F_(1,120) > 10.16; p < 0.005). A positive correlation was found between the olfactory scores and the number of hours per week dedicated to physical activities (Pearson’s r > 0.32, p ≤ 0.014) in both active and inactive ES.

Conclusions: High levels of exercise and non-exercise physical activity are strongly associated with the olfactory function and, consequently, with the quality of life of the elderly. Given the limited physical exercise of elderly people, they can benefit from a more active lifestyle by increasing non-exercise physical activities.

COVID-19 Immunobiology: Lessons Learned, New Questions Arise

There is strong evidence that COVID-19 pathophysiology is mainly driven by a spatiotemporal immune deregulation. Both its phenotypic heterogeneity, spanning from asymptomatic to severe disease/death, and its associated mortality, are dictated by and linked to maladaptive innate and adaptive immune responses against SARS-CoV-2, the etiologic factor of the disease. Deregulated interferon and cytokine responses, with the contribution of immune and cellular stress-response mediators (like cellular senescence or uncontrolled inflammatory cell death), result in innate and adaptive immune system malfunction, endothelial activation and inflammation (endothelitis), as well as immunothrombosis (with enhanced platelet activation, NET production/release and complement hyper-activation). All these factors play key roles in the development of severe COVID-19. Interestingly, another consequence of this immune deregulation, is the production of autoantibodies and the subsequent development of autoimmune phenomena observed in some COVID-19 patients with severe disease. These new aspects of the disease that are now emerging (like autoimmunity and cellular senescence), could offer us new opportunities in the field of disease prevention and treatment. Simultaneously, lessons already learned from the immunobiology of COVID-19 could offer new insights, not only for this disease, but also for a variety of chronic inflammatory responses observed in autoimmune and (auto)inflammatory diseases.

Olfactory Function in Patients with Inflammatory Bowel Disease (IBD) Is Associated with Their Body Mass Index and Polymorphism in the Odor Binding-Protein (OBPIIa) Gene

Smell strongly contributes to food choice and intake, influencing energy balance and body weight; its reduction or loss has been related to malnutrition problems. Some patients with inflammatory bowel disease (IBD), mainly Crohn’s disease (CD) and ulcerative colitis (UC), are underweight, while others are overweight. Some studies suggest that changes in eating habits could be linked to specific disorders of the olfactory functions. We assessed the olfactory performance in 199 subjects (healthy control (HC) n = 99, IBD n = 100), based on the olfactory Threshold, Discrimination and Identification score (TDI score), measured with the “Sniffin’ Sticks” test. Subjects were genotyped for the rs2590498 polymorphism of the OBPIIa gene. IBD patients showed both a slightly, but significantly, lower olfactory function and a higher BMI compared to HC subjects. Threshold (in both population) and Discrimination (in IBD patients) olfactory score were affected by the OBPIIa genotype. BMI was influenced by both health status and OBPIIa genotype. A lower olfactory function may delay the satiety sensation and thus increase meal duration and body weight in IBD patients. However, the AA genotype of the OBPIIa seems to “protect” IBD patients from more severe olfactory dysfunction.

The SARS-CoV-2 as an instrumental trigger of autoimmunity

Autoimmunity may be generated by a variety of factors by creating a hyper-stimulated state of the immune system. It had been established long ago that viruses are a substantial component of environmental factors that contribute to the production of autoimmune antibodies, as well as autoimmune diseases. Epstein-Barr virus (EBV), cytomegalovirus (CMV) and human immunodeficiency virus (HIV) are viruses that withhold these autoimmune abilities. In a similar manner, SARS-CoV-2 may be counted to similar manifestations, as numerous records demonstrating the likelihood of COVID-19 patients to develop multiple types of autoantibodies and autoimmune diseases. In this review, we focused on the association between COVID-19 and the immune system concerning the tendency of patients to develop over 15 separate types of autoantibodies and above 10 distinct autoimmune diseases. An additional autoimmunity manifestation may be one of the common initial symptoms in COVID-19 patients, anosmia, the complete loss of the ability to sense smell, and other olfactory alterations. We summarize current knowledge on principal mechanisms that may contribute to the development of autoimmunity in the disease: the ability of SARS-CoV-2 to hyper-stimulate the immune system, induce excessive neutrophil extracellular traps formation with neutrophil-associated cytokine responses and the molecular resemblance between self-components of the host and the virus. Additionally, we will examine COVID-19 potential risk on the new-onsets of autoimmune diseases, such as antiphospholipid syndrome, Guillain-Barré syndrome, Kawasaki disease and numerous others. It is of great importance to recognize those autoimmune manifestations of COVID-19 in order to properly cope with their outcomes in the ongoing pandemic and the long-term post-pandemic period. Lastly, an effective vaccine against SARS-CoV-2 may be the best solution in dealing with the ongoing pandemic. We will discuss the new messenger RNA vaccination strategy with an emphasis on autoimmunity implications.

Acute Systemic Experimental Inflammation Does Not Reduce Human Odor Identification Performance

Olfactory dysfunction is a common symptom of various diseases, but the underlying pathophysiology has not been fully understood. Evidence from both animal and human studies suggests that local inflammation of the olfactory epithelium is linked to olfactory dysfunction. However, whether systemic inflammation causes olfactory dysfunction is yet to be determined. In the present behavioral study, we set out to test whether acute systemic inflammation impairs olfactory identification performance by inducing a transient and controlled state of systemic inflammation using an experimental endotoxemia model. We treated young healthy participants (N = 20) with a relatively high dose (2.0 ng/kg) of lipopolysaccharide (LPS) and a placebo treatment in a double-blind within-subject design, and assessed participants’ ability to identify odors using the MONEX-40, a reliable method for experimental assessment of odor identification ability in healthy and young individuals. Our results show that olfactory identification performance was not affected by the acute systemic inflammation triggered by the injection of LPS. Moreover, odor identification performance following the LPS injection was not associated with levels of circulating proinflammatory cytokines (interleukin-6, interleukin-8, and tumor necrosis factor-α). Because experimental LPS-induced systemic inflammation does not affect olfactory identification performance, our findings suggest that chronic, rather than transient, systemic inflammation is a more likely mechanism to explore in order to explain the olfactory deficits observed in inflammatory diseases.

Effects of In Vivo Gluten Challenge on PBMC Gene Expression Profiles in Diet Treated Celiac Disease

The pathological mechanisms that lead to the onset and reactivation of celiac disease (CD) remain largely unknown. While gluten free diet (GFD) improves the intestinal damage and associated clinical symptoms in majority of cases, it falls short of providing full recovery. Additionally, late or misdiagnosis is also common as CD presents with a wide range of symptoms. Clear understanding of CD pathogenesis is thus critical to address both diagnostic and treatment concerns. We aimed to study the molecular impact of short gluten exposure in GFD treated CD patients, as well as identify biological pathways that remain altered constitutively in CD regardless of treatment. Using RNAseq profiling of PBMC samples collected from treated CD patients and gluten challenged patient and healthy controls, we explored the peripheral transcriptome in CD patients following a short gluten exposure. Short gluten exposure of just three days was enough to alter the genome-wide PBMC transcriptome of patients. Pathway analysis revealed gluten-induced upregulation of mainly immune response related pathways, both innate and adaptive, in CD patients. We evaluated the perturbation of biological pathways in sample-specific manner. Compared to gluten exposed healthy controls, pathways related to tight junction, olfactory transduction, metabolism of unsaturated fatty acids (such as arachidonic acid), metabolism of amino acids (such as cysteine and glutamate), and microbial infection were constitutively altered in CD patients regardless of treatment, while GFD treatment appears to mostly normalize immune response pathways to "healthy" state. Upstream regulator prediction analysis using differentially expressed genes identified constitutively activated regulators relatively proximal to previously reported CD associated loci, particularly SMARCA4 on 19p13.2 and CSF2 on 5q31. We also found constitutively upregulated genes in CD that are in CD associated genetic loci such as MEF2BNB-MEF2B (BORCS8-MEF2B) on 19p13.11 and CSTB on 21q22.3. RNAseq revealed strong effects of short oral gluten challenge on whole PBMC fraction and constitutively altered pathways in CD PBMC suggesting important factors other than gluten in CD pathogenesis.

Olfactory Function Is Impaired in Patients with Mastocytosis

BACKGROUND

Mastocytosis is a clinically heterogeneous disorder associated with abnormal mast cell accumulation in different organs. No data are available as regards the assessment of olfactory function and its association with mastocytosis.

OBJECTIVE

The aim of the study was first to investigate odor threshold, discrimination, and identification in patients with mastocytosis compared with age-matched healthy controls (HC), and furthermore, to correlate olfactory function with the other clinical symptoms of mastocytosis.

METHODS

Eighty-one participants were enrolled: 41 patients with mastocytosis (23 males and 18 females; mean age, 47.95 years; standard deviation [SD], 14.7 years) were compared with 40 HC (23 males and 17 females; mean age, 47.88 years; SD, 14.6 years). Olfactory function among participants was evaluated using the "Sniffin' Sticks" test for odor detection threshold (OT), odor discrimination (OD), and odor identification (OI).

RESULTS

Patients with systemic mastocytosis showed a significant decrease in the total olfactory function (Threshold-Discrimination-Identification [TDI] score), OT, OD, and OI compared with HC. A significant negative correlation was observed only between TDI score and serum tryptase concentration (μg/L). No correlation was observed between disease duration versus OT, OD, OI, and TDI score.

CONCLUSIONS

Our results suggest that the olfactory function is impaired in patients compared with HC; a significant negative correlation was found between TDI score and the level of serum tryptase. Olfactory dysfunction in mastocytosis may be considered among the clinical manifestations contributing to the burden of this disease.

Neuropsychiatric lupus: new mechanistic insights and future treatment directions

Patients with systemic lupus erythematosus (SLE) frequently show symptoms of central nervous system (CNS) involvement, termed neuropsychiatric SLE (NPSLE). The CNS manifestations of SLE are diverse and have a broad spectrum of severity and prognostic implications. Patients with NPSLE typically present with nonspecific symptoms, such as headache and cognitive impairment, but might also experience devastating features, such as memory loss, seizures and stroke. Some features of NPSLE, in particular those related to coagulopathy, have been characterized and an evidence-based treatment algorithm is available. The cognitive and affective manifestations of NPSLE, however, remain poorly understood. Various immune effectors have been evaluated as contributors to its pathogenesis, including brain-reactive autoantibodies, cytokines and cell-mediated inflammation. Additional brain-intrinsic elements (such as resident microglia, the blood-brain barrier and other neurovascular interfaces) are important facilitators of NPSLE. As yet, however, no unifying model has been found to underlie the pathogenesis of NPSLE, suggesting that this disease has multiple contributors and perhaps several distinct aetiologies. This heterogeneity presents a challenge for clinicians who have traditionally relied on empirical judgement in choosing treatment modalities for patients with NPSLE. Improved understanding of this manifestation of SLE might yield further options for managing this disease.

Sex Effects on Gene Expression in Lacrimal Glands of Mouse Models of Sjögren Syndrome

Purpose

Sjögren syndrome is an autoimmune disease that occurs primarily in women, and is associated with lacrimal gland inflammation and aqueous-deficient dry eye. We hypothesize that sex-associated differences in lacrimal gland gene expression are very important in promoting lymphocyte accumulation in this tissue and contribute to the onset, progression, and/or severity of the inflammatory disease process. To test our hypothesis, we explored the nature and extent of sex-related differences in gene expression in autoimmune lacrimal glands.

Methods

Lacrimal glands were collected from age-matched, adult, male and female MRL/MpJ-Tnfrsf6^lpr (MRL/lpr) and nonobese diabetic/LtJ (NOD) mice. Glands were processed for the analysis of differentially expressed mRNAs by using CodeLink Bioarrays and Affymetrix GeneChips. Data were evaluated with bioinformatics and statistical software.

Results

Our results show that sex significantly influences the expression of thousands of genes in lacrimal glands of MRL/lpr and NOD mice. The immune nature of this glandular response is very dependent on the Sjögren syndrome model. Lacrimal glands of female, as compared with male, MRL/lpr mice contain a significant increase in the expression of genes related to inflammatory responses, antigen processing, and chemokine pathways. In contrast, it is the lacrimal tissue of NOD males, and not females, that presents with a significantly greater expression of immune-related genes.

Conclusions

These data support our hypothesis that sex-related differences in gene expression contribute to lacrimal gland disease in Sjögren syndrome. Our findings also suggest that factors in the lacrimal gland microenvironment are critically important in mediating these sex-associated immune effects.

Deciphering the Odorant Binding, Activation, and Discrimination Mechanism of Dhelobp21 from Dastarus Helophoroides

Odorant-binding proteins (OBPs) play a pivotal role in transporting odorants through the sensillar lymph of insect chemosensory sensilla and increasing the sensitivity of the olfactory system. To address the ligand binding, activation, and release mechanisms of OBPs, we performed a set of conventional molecular dynamics simulations for binding of the odorant-binding protein DhelOBP21 from Dastarcus helophoroides with 18 ligands (1-NPN and 17 volatiles), as well as four constant-pH molecular dynamics simulations. We found that the open pocket DhelOBP21 at pH 5.0 could bind volatiles and form a closed pocket complex via transformation of its N-terminus into regular Helix at pH 7.0 and vice versa. Moreover, the discrimination of volatiles (selectivity and promiscuity) was determined by the characteristics of both the volatiles and the ‘essential’ and ‘selective’ amino acid residues in OBP binding pockets, rather than the binding affinity of the volatiles. This study put forward a new hypothesis that during the binding of volatiles there are two transitions for the DhelOBP21 amino-terminus: pH- and odorant binding-dependent random-coil-to-helix. Another important finding is providing a framework for the exploration of the complete coil-to-helix transition process and theoretically analyzing its underlying causes at molecular level.

Olfactory Receptors in Non-Chemosensory Organs: The Nervous System in Health and Disease

Olfactory receptors (ORs) and down-stream functional signaling molecules adenylyl cyclase 3 (AC3), olfactory G protein α subunit (Gαolf), OR transporters receptor transporter proteins 1 and 2 (RTP1 and RTP2), receptor expression enhancing protein 1 (REEP1), and UDP-glucuronosyltransferases (UGTs) are expressed in neurons of the human and murine central nervous system (CNS). In vitro studies have shown that these receptors react to external stimuli and therefore are equipped to be functional. However, ORs are not directly related to the detection of odors. Several molecules delivered from the blood, cerebrospinal fluid, neighboring local neurons and glial cells, distant cells through the extracellular space, and the cells’ own self-regulating internal homeostasis can be postulated as possible ligands. Moreover, a single neuron outside the olfactory epithelium expresses more than one receptor, and the mechanism of transcriptional regulation may be different in olfactory epithelia and brain neurons. OR gene expression is altered in several neurodegenerative diseases including Parkinson’s disease (PD), Alzheimer’s disease (AD), progressive supranuclear palsy (PSP) and sporadic Creutzfeldt-Jakob disease (sCJD) subtypes MM1 and VV2 with disease-, region- and subtype-specific patterns. Altered gene expression is also observed in the prefrontal cortex in schizophrenia with a major but not total influence of chlorpromazine treatment. Preliminary parallel observations have also shown the presence of taste receptors (TASRs), mainly of the bitter taste family, in the mammalian brain, whose function is not related to taste. TASRs in brain are also abnormally regulated in neurodegenerative diseases. These seminal observations point to the need for further studies on ORs and TASRs chemoreceptors in the mammalian brain.

Olfactory functions in patients with psoriasis vulgaris: correlations with the severity of the disease

It is well known that psoriasis is not only limited to skin, but a systemic autoimmune disease with various comorbidities. Olfactory dysfunction, one of as a common but lesser known symptom of patients with autoimmune diseases, often presents with smell loss. The aim of this study was to assess the olfactory functions in patients with psoriasis and to compare with healthy controls. A total of 50 patients with psoriasis and 43 control subjects were included to the study. The clinical severity of psoriasis was calculated by psoriasis area and severity index (PASI). Patients were classified into two groups according to PASI score as mild (PASI ≤10) and moderate-severe (PASI >10). Olfactory function was evaluated with "Sniffin'Sticks" test. Total test scores (max. 48 points) of threshold, discrimination, and identification (TDI) were classified as normal olfaction = normosmia (>30.3 points), decreased olfaction = hyposmia (16.5-30.3 points) and loss of olfaction = anosmia (<16.5 points). Psoriasis patients had significantly lower smell scores compared with healthy controls (p < 0.001). Of the 50 psoriasis patients, 40 (80 %) were hyposmic. We found negative correlation between TDI and PASI (r = -0.34, p = 0.014). The TDI scores of the patients with moderate-severe psoriasis (PASI score >10) were found to be significantly lower than the patients with mild psoriasis (PASI ≤10) (p < 0.001). Olfactory dysfunction in patients with psoriasis could be thought as a comorbidity as in other inflammatory disorders. Physicians should be aware of olfactory impairment when evaluating psoriasis patients in their clinical practice.

Olfactory dysfunction in Multiple Sclerosis: A scoping review of the literature

OBJECTIVE

Olfactory dysfunction in Multiple Sclerosis (MS) has been reported, but results have been inconsistent. In this review we describe, synthesize, and interpret the existing literature on olfactory dysfunction in Multiple Sclerosis and identify gaps in the current level of knowledge.

METHODS

The study design was a scoping review of the literature covering several study designs. Systematic Searches of the PubMed, CINAHL, Cochrane Library, Web of Science, PsycARTICLES, PsycINFO and Google Scholar databases were conducted that included key words related to Multiple Sclerosis and Olfaction Disorders. Literature that met the criteria of pertaining to both Multiple Sclerosis and olfactory dysfunction was identified, with the aim of providing an overview of the extent and types of research available in this area.

RESULTS

Sixty-one reports were identified in the initial search, with 40 meeting the study criteria. Twenty-five clinical studies were included. Among them, 23 studies measured for olfactory dysfunction in MS patients, ten evaluated MRI correlates of olfactory dysfunction, and five evaluated neurophysiology correlates of olfactory dysfunction. Six of the included studies were abstracts. In addition, thirteen reviews/commentaries and two case studies were included. The majority of the studies identified some degree of olfactory dysfunction in MS patients, and various aspects and correlations with olfactory impairment were observed.

CONCLUSIONS

The overall weight of the literature suggests that olfactory dysfunction may occur in MS. Although there is variability in reported frequency, the more robust studies suggest the prevalence is significant, ranging from 20% to 45% in the MS population. Despite this, the mechanisms are unknown and the clinical relevance of this association has not been well explored. Interesting findings relating mood disorders, cognition, and olfactory dysfunction in MS are also suggested but remain poorly developed and require further investigation. Future studies are also warranted to understand the dynamic changes in olfactory function during the course of MS, and to correlate olfactory function with relapses/disease activity.

Impaired sense of smell and altered olfactory system in RAG-1(-∕-) immunodeficient mice

Immune deficiencies are often associated with a number of physical manifestations including loss of sense of smell and an increased level of anxiety. We have previously shown that T and B cell-deficient recombinase activating gene (RAG-1)(-∕-) knockout mice have an increased level of anxiety-like behavior and altered gene expression involved in olfaction. In this study, we expanded these findings by testing the structure and functional development of the olfactory system in RAG-1 (-∕-) mice. Our results show that these mice have a reduced engagement in different types of odors and this phenotype is associated with disorganized architecture of glomerular tissue and atrophy of the main olfactory epithelium. Most intriguingly this defect manifests specifically in adult age and is not due to impairment in the patterning of the olfactory neuron staining at the embryo stage. Together these findings provide a formerly unreported biological evidence for an altered function of the olfactory system in RAG-1 (-∕-) mice.

Autoimmunity in 2013

The peer-reviewed publications in the field of autoimmunity published in 2013 represented a significant proportion of immunology articles and grew since the previous year to indicate that more immune-mediated phenomena may recognize an autoimmune mechanism and illustrated by osteoarthritis and atherosclerosis. As a result, our understanding of the mechanisms of autoimmunity is becoming the paradigm for translational research in which the progress in disease pathogenesis for both tolerance breakdown and inflammation perpetuation is rapidly followed by new treatment approaches and clinical management changes. The similarities across the autoimmune disease spectrum outnumber differences, particularly when treatments are compared. Indeed, the therapeutics of autoimmune diseases are based on a growing armamentarium that currently includes monoclonal antibodies and small molecules which act by targeting molecular markers or intracellular mediators with high specificity. Among the over 100 conditions considered as autoimmune, the common grounds are well illustrated by the data reported for systemic lupus erythematosus and rheumatoid arthritis or by the plethora of studies on Th17 cells and biomarkers, particularly serum autoantibodies. Further, we are particularly intrigued by studies on the genomics, epigenetics, and microRNA at different stages of disease development or on the safe and effective use of abatacept acting on the costimulation of T and B cells in rheumatoid arthritis. We are convinced that the data published in 2013 represent a promising background for future developments that will exponentially impact the work of laboratory and clinical scientists over the next years.

Olfactory impairment in patients with the fibromyalgia syndrome and systemic sclerosis

Patients with autoimmune diseases often present with olfactory impairment. The aim of the study was to assess the olfactory functions of female patients with fibromyalgia (FM) compared with patients with systemic sclerosis (SSc) and with healthy female controls. Olfactory functions were assessed in 24 patients with FM, 20 patients with SSc and 21 age-matched healthy controls. The sense of smell was evaluated using the Sniffin' Sticks test including the three stages of smell: threshold, discrimination, and identification (TDI) of the different odors. The severity of fibromyalgia was assessed using the fibromyalgia impact questionnaire (FIQ). The short form 36 (SF-36) questionnaire was also completed in order to seek a relationship between the patients perception of quality of life and the different aspects of the smell sense. Depression was evaluated in both FM and SSc patients utilizing the Beck depression inventory-II (BDI-II) questionnaire. Patients with FM had significantly lower TDI smell scores compared with both SSc patients and healthy controls (p < 0.005, One-Way ANOVA). Hyposmia (defined as TDI scores below 30) were observed in 14 of 24 (42 %) patients with FM compared to 3 of 20 (15 %) patients with SSc and 1 of the healthy controls (4.3 %) (p < 0.02). FM patients had significantly lower thresholds of smell compared to both healthy controls and patients with SSc (p < 0.001), whereas for patients with SSc only the ability to discriminate between odors was impaired (p < 0.006). We could not detect any statistical correlation between smell abilities and clinical manifestation of SSc or the FIQ and SF-36 scores among FM patients. However the correlation between depression, defined by the BDI-II score, and the sense of smell differed between patients with FM and patients with SSc. As only among SSc patients a lower sense of smell correlated with a higher BDI-II score (p = 0.02). Our findings suggest that there is a decrease in the sense of smell both in FM and SSc patients compared with healthy controls. However these impairments differ between patients group and might represent different mechanisms that affect the sense of smell.

Individual olfactory perception reveals meaningful nonolfactory genetic information

Each person expresses a potentially unique subset of ∼ 400 different olfactory receptor subtypes. Given that the receptors we express partially determine the odors we smell, it follows that each person may have a unique nose; to capture this, we devised a sensitive test of olfactory perception we termed the "olfactory fingerprint." Olfactory fingerprints relied on matrices of perceived odorant similarity derived from descriptors applied to the odorants. We initially fingerprinted 89 individuals using 28 odors and 54 descriptors. We found that each person had a unique olfactory fingerprint (P < 10(-10)), which was odor specific but descriptor independent. We could identify individuals from this pool using randomly selected sets of 7 odors and 11 descriptors alone. Extrapolating from this data, we determined that using 34 odors and 35 descriptors we could individually identify each of the 7 billion people on earth. Olfactory perception, however, fluctuates over time, calling into question our proposed perceptual readout of presumably stable genetic makeup. To test whether fingerprints remain informative despite this temporal fluctuation, building on the linkage between olfactory receptors and HLA, we hypothesized that olfactory perception may relate to HLA. We obtained olfactory fingerprints and HLA typing for 130 individuals, and found that olfactory fingerprint matching using only four odorants was significantly related to HLA matching (P < 10(-4)), such that olfactory fingerprints can save 32% of HLA tests in a population screen (P < 10(-6)). In conclusion, a precise measure of olfactory perception reveals meaningful nonolfactory genetic information.

Prolactin and natural killer cells: evaluating the neuroendocrine-immune axis in women with primary infertility and recurrent spontaneous abortion

PROBLEM

An association between serum prolactin (PRL) and peripheral blood natural killer (NK) cells has been described in healthy women. We explored for the first time the PRL response to the thyrotrophin-releasing hormone (TRH) test and the association between PRL and NK cells in women with reproductive failure.

METHODS

A total of 130 women [31 primary infertility, 69 recurrent spontaneous abortion (RSA), and 30 fertile women] were evaluated by a TRH test to analyze the following: basal PRL (bPRL), peak-time PRL, PRL absolute and relative increase, decline-time PRL. Hyperprolactinaemia (HPRL) was defined as bPRL ≥15 ng/mL. NK cells were characterized by immunophenotyping.

RESULTS

Significantly higher bPRL levels were found in the infertile women than in controls. Both the infertile and the RSA women showed significantly elevated NK levels. bPRL levels correlated with NK cells in HPRL-infertile women.

CONCLUSIONS

In patients with HPRL, an association between NK cell and bPRL results. The dynamic test in the infertile women would help in the management of the pregnancy impairment.

Possible link between Toxoplasma gondii and the anosmia associated with neurodegenerative diseases

Toxoplasma gondii is an intracellular protozoan infecting 30% to 50% of global human population. Recently, it was suggested that chronic latent neuroinflammation caused by the parasite may be responsible for the development of several neurodegenerative diseases manifesting with the loss of smell. Studies in animals inoculated with the parasite revealed cysts in various regions of the brain, including olfactory bulb. Development of behavioral changes was paralleled by the preferential persistence of cysts in defined anatomic structures of the brain, depending on the host, strain of the parasite, its virulence, and route of inoculation. Olfactory dysfunction reported in Alzheimer's disease, multiple sclerosis, and schizophrenia was frequently associated with the significantly increased serum anti-T gondii immunoglobulin G antibody levels. Damage of the olfactory system may be also at least in part responsible for the development of depression because T gondii infection worsened mood in such patients, and the olfactory bulbectomized rat serves as a model of depression.

Alexithymia, mood states and pain experience in systemic lupus erythematosus and rheumatoid arthritis

This prospective study aims to examine alexithymia, mood states and pain experience in systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) patients. We enrolled 49 patients with SLE or RA. All patients were evaluated through a set of questionnaires: (1) the Toronto Alexithymia Scale-20 (TAS), (2) the Profile of Mood States (POMS) and (3) visual analogue scale (VAS) and Questionario Italiano sul Dolore, self-report measures to assess pain intensity. Alexithymia was more prevalent in RA (44 %) than in SLE (37.5 %). The mean values of VAS were significantly higher in RA than in SLE population (p < 0.05). A linear relation between TAS and VAS values has been found in SLE (R = 0.714, p < 0.0001). The mean values of POMS regarding all negative dimensions of mood were higher in SLE than in RA. There was a linear relationship between TAS and POMS values in SLE patients (R = 0.7, p < 0.001). We found a high prevalence of alexithymia in SLE and RA. The chronic pain is influenced by emotional status as documented by a linear relation between TAS and VAS values in SLE patients. The difficulty in reporting emotional responses in these patients seems to be mediated by negative mood states.

Autoimmunity in 2012

The initiation and perpetuation of autoimmunity recognize numerous checkpoints, from the genomic susceptibility to the breakdown of tolerance. This latter phenomenon includes the loss of B cell anergy and T regulatory cell failure, as well as the production of autoantibodies and autoreactive T cells. These mechanisms ultimately lead to tissue injury via different mechanisms that span from the production of proinflammatory cytokines to the chemotaxis of immune cells to the target sites. The pathways to autoimmunity have been widely investigated over the past year and resulted in a number of articles in peer-reviewed journals that has increased by nearly 10 % compared to 2011. We herein follow on the attempt to provide a brief discussion of the majority of articles on autoimmune diseases that were published in the major immunology journals in the previous solar year. The selection is necessarily arbitrary and may thus not be seen as comprehensive but reflects current research trends. Indeed, 2012 articles were mostly dedicated to define new and old mechanisms with potential therapeutic implications in autoimmunity in general, though based on specific clinical conditions or animal models. As paradigmatic examples, the environmental influence on autoimmunity, Th17 changes modulating the autoimmune response, serum autoantibodies and B cell changes as biomarkers and therapeutic targets were major issues addressed by experimental articles in 2012. Further, a growing number of studies investigated the sex bias of autoimmunity and supported different working hypotheses to explain the female predominance, including sex chromosome changes and reproductive life factors. In conclusion, the resulting scenario illustrates that common factors may underlie different autoimmune diseases and this is well represented by the observed alterations in interferon-α and TGFβ or by the shared signaling pathways.

Less travelled roads in clinical immunology and allergy: drug reactions and the environmental influence

Allergy and clinical immunology are examples of areas of knowledge in which working hypotheses are dominant over mechanistic understanding. As such, sometimes scientific efforts follow major streams and overlook some epidemiologically prevalent conditions that thus become underestimated by the research community. For this reason, we welcome the present issue of Clinical Reviews in Allergy and Immunology that is dedicated to uncommon themes in clinical immunology and allergy. First, comprehensive discussions are provided for allergy phenomena of large potential impact in clinical practice such as reactions to cephalosporins or aspirin-induced asthma and in everyday life such as allergies to food additives or legumes. Further, the issue addresses other uncommon themes such as urticaria and angioedema, cercarial dermatitis, or late-onset inflammation to soft tissue fillers. Last, there will be discussion on transversal issues such as olfactory defects in autoimmunity, interleukin 1 beta pathway, and the search for new serological markers in chronic inflammation. As a result, we are convinced that this issue will be of help to clinicians involved in internal medicine as well as to allergists and clinical immunologists. More importantly, we are convinced that these discussions will be of interest also to basic scientists for the numerous translational implications.

Smell and taste in inflammatory bowel disease

Objective

To investigate the olfactory/gustatory functions of patients with inflammatory bowel disease (IBD) by smell/taste tests, and to determine if disease activity or medication might influence the olfactory/gustatory functions of patients.

Patients and Methods

In total, 59 IBD patients (37 Crohn's disease (CD) and 22 ulcerative colitis (UC) patients) were studied using “Sniffin' sticks” and “taste strips” for olfactory and gustatory tests, respectively, and compared to healthy controls and published normative data.

Results

Among IBD (CD and UC) patients, the values for odor threshold, but not for odor identification or discrimination, were significantly lower than that of the normative data. Further, these patients showed lower values than the normative taste values and the control group for all tastes, except sour; 57.6% of the IBD patients were hyposmic, while 30.5% were hypogeusic. Subjective self-assessments showed that the patients were not aware of their reduced olfactory/gustatory functions. There were no relevant differences in taste and smell abilities between the CD and UC patients. Disease activity and treatment did not influence the olfactory/gustatory functions.

Conclusion

IBD (CD and UC) patients exhibited significant reductions in the olfactory and gustatory functions. Therefore, patients should be tested by smell/taste tests, in order to be adequately informed of their olfactory/gustatory functions and provided an understanding of how to overcome their limitations, and thus improve their quality of life.

Novel pebbles in the mosaic of autoimmunity

Almost 25 years ago, the concept of the 'mosaic of autoimmunity' was introduced to the scientific community, and since then this concept has continuously evolved, with new pebbles being added regularly. We are now looking at an era in which the players of autoimmunity have changed names and roles. In this issue of BMC Medicine, several aspects of autoimmunity have been addressed, suggesting that we are now at the forefront of autoimmunity science. Within the environmental factors generating autoimmunity are now included unsuspected molecules such as vitamin D and aluminum. Some adjuvants such as aluminum are recognized as causal factors in the development of the autoimmune response. An entirely new syndrome, the autoimmune/inflammatory syndrome induced by adjuvants (ASIA), has been recently described. This is the new wind blowing within the branches of autoimmunity, adding knowledge to physicians for helping patients with autoimmune disease.