Recent developments and highlights in immune monitoring of allergen immunotherapy

Allergic diseases are the most common chronic immune‐mediated disorders and can manifest with an enormous diversity in clinical severity and symptoms. Underlying mechanisms for the adverse immune response to allergens and its downregulation by treatment are still being revealed. As a result, there have been, and still are, major challenges in diagnosis, prediction of disease progression/evolution and treatment. Currently, the only corrective treatment available is allergen immunotherapy (AIT). AIT modifies the immune response through long‐term repeated exposure to defined doses of allergen. However, as the treatment usually needs to be continued for several years to be effective, and can be accompanied by adverse reactions, many patients face difficulties completing their schedule. Long‐term therapy also potentially incurs high costs. Therefore, there is a great need for objective markers to predict or to monitor individual patient's beneficial changes in immune response during therapy so that efficacy can be identified as early as possible. In this review, we specifically address recent technical developments that have generated new insights into allergic disease pathogenesis, and how these could potentially be translated into routine laboratory assays for disease monitoring during AIT that are relatively inexpensive, robust and scalable.     

Persistence of Neutralizing Antibodies to SARS-CoV-2 in First Wave Infected Individuals at Ten Months Post-Infection: The UnIRSA Cohort Study

Longitudinal mapping of antibody-based SARS-CoV-2 immunity is critical for public health control of the pandemic and vaccine development. We performed a longitudinal analysis of the antibody-based immune response in a cohort of 100 COVID-19 individuals who were infected during the first wave of infection in northern Italy. The SARS-CoV-2 humoral response was tested using the COVID-SeroIndex, Kantaro Quantitative SARS-CoV-2 IgG Antibody RUO Kit (R&D Systems, Bio-Techne, Minneapolis, USA) and pseudotype-based neutralizing antibody assay. Using sequential serum samples collected from 100 COVID-19 recovered individuals from northern Italy—mostly with mild disease—at 2 and 10 months after their first positive PCR test, we show that 93% of them seroconverted at 2 months, with a geometric mean (GeoMean) half-maximal neutralization titer (NT50) of 387.9. Among the 35 unvaccinated subjects retested at 10 months, 7 resulted seronegative, with an 80% drop in seropositivity, while 28 showed decreased anti-receptor binding domain (RBD) and anti-spike (S) IgG titers, with a GeoMean NT50 neutralization titer dropping to 163.5. As an NT50 > 100 is known to confer protection from SARS-CoV-2 re-infection, our data show that the neutralizing activity elicited by the natural infection has lasted for at least 10 months in a large fraction of subjects.     

Requirement for an Otopetrin-like protein for acid taste in Drosophila

Receptors for bitter, sugar, and other tastes have been identified in the fruit fly Drosophila melanogaster, while a broadly tuned receptor for the taste of acid has been elusive. Previous work showed that such a receptor was unlikely to be encoded by a gene within one of the two major families of taste receptors in Drosophila, the “gustatory receptors” and “ionotropic receptors.” Here, to identify the acid taste receptor, we tested the contributions of genes encoding proteins distantly related to the mammalian Otopertrin1 (OTOP1) proton channel that functions as a sour receptor in mice. RNA interference (RNAi) knockdown or mutation by CRISPR/Cas9 of one of the genes, Otopetrin-Like A (OtopLA), but not of the others (OtopLB or OtopLC) severely impaired the behavioral rejection to a sweet solution laced with high levels of HCl or carboxylic acids and greatly reduced acid-induced action potentials measured from taste hairs. An isoform of OtopLA that we isolated from the proboscis was sufficient to restore behavioral sensitivity and acid-induced action potential firing in OtopLA mutant flies. At lower concentrations, HCl was attractive to the flies, and this attraction was abolished in the OtopLA mutant. Cell type–specific rescue experiments showed that OtopLA functions in distinct subsets of gustatory receptor neurons for repulsion and attraction to high and low levels of protons, respectively. This work highlights a functional conservation of a sensory receptor in flies and mammals and shows that the same receptor can function in both appetitive and repulsive behaviors.

Humans possess the ability to distinguish among five basic tastes: sweet, bitter, salt, sour, and umami. Interestingly, there is considerable variety in the ability of other mammals to detect these qualities. For example, cats are missing sweet taste (1) and the bottlenose dolphin only detects salt in food (2). Yet the fruit fly, Drosophila melanogaster, responds to a similar repertoire of tastes as humans. This is all the more remarkable given the very distant evolutionary relatedness and the enormous differences in the anatomy of the fly and mammalian taste organs and points to a conserved function of these taste qualities in assessing food quality.Many of the receptors involved in Drosophila taste have been defined (3, 4). Those that contribute to sweet and bitter tastes have been characterized extensively and are members of the “gustatory receptor” (GR) family (3, 4). GRs are unrelated to the G protein–coupled receptors that function in mammalian sweet and bitter taste (3). Therefore, the abilities of insects and humans to respond to similar repertoires of chemicals such as sweet and bitter tastants have emerged independently.In mice, the taste of acids depends on a proton-selective channel, Otopetrin1 (OTOP1), which is expressed in type III taste receptor cells (5–7). OTOP1 was first identified based on its essential role in the vestibular systems of the mouse and zebrafish (8–11) and was found to encode a family of proton-selective ion channels functionally conserved from worms to humans (5, 9, 12). In sea urchins, an Otop channel functions in calcifying primary mesenchymal cells by promoting the removal of protons generated during the production of CaCO₃ (13). Otop family members are structurally unrelated to other ion channels and are composed of 12 transmembrane segments (12, 14, 15), which assemble as a dimer with no obvious permeation pathway (14, 15). Flies, mice, and human genomes each contain three otop genes, although the fly genes are not direct homologs of the vertebrate genes (9).In Drosophila, low or moderate levels of some organic acids are attractive and promote feeding, while the same acids at higher concentrations repress food consumption (16, 17). This rejection contributes to survival as it discourages the animals from eating very acidic foods in the environment that can decrease lifespan. Two members of the large family of “ionotropic receptors” (IRs; IR25a and IR76b) function in GR neurons (GRNs) in the legs for sensing carboxylic acids and HCl (18). Mutation of either of these IRs disrupts the preference to lay eggs on acid-containing substrates (18). Flies prefer consuming lactic acid over water, and this preference is mildly reduced in Ir25a mutants (19).The receptors required for the gustatory rejection of noxious levels of acids have been largely enigmatic. An exception is IR7a, which is needed to suppress feeding on foods laced with acetic acid (17). IR7a is very narrowly tuned, as it does not impair the rejection of foods with HCl or any other carboxylic acid tested. This receptor acts in a subset of GRNs called B GRNs that are also activated by bitter chemicals and certain other aversive compounds (4, 17).Here, we identified a member of the family of Otop channels that in Drosophila is required for the detection of protons in food. Wild-type flies are strongly repelled by high levels of HCl and mildly attracted to a low level of HCl. We found that these responses depend on the Otopetrin-Like protein (OtopLA), which has a common evolutionarily origin with mammalian OTOP channels. By performing cell type–specific rescue experiments, we found that the strong repulsion and mild attraction to different levels of acids depends on expression of OtopLA in distinct subsets of GRNs.     

A large pelvic mass in an adolescent patient with granulomatous nephritis: case report and discussion of treatment challenges

BACKGROUND: An adolescent patient with granulomatous nephritis presents with a large, solid pelvic mass. Pertinent differential diagnosis for this solid ovarian mass as well as discussion regarding treatment challenges for this patient is delineated. CASE: A 15-year-old female presented to her primary care doctor with fatigue and syncope. Initial laboratory workup revealed a hemoglobin of 7.9 g/dL, an elevated creatinine of 3.5 mmol/L, and an elevated ionized calcium of 13.1 mg/dL. Renal biopsy revealed diffuse non-caseating granulomatous nephritis with rare acid-fast bacilli. Renal ultrasound first noted a pelvic mass. Pelvic ultrasound revealed a 15.0 x 8.4 x 12.2 cm mass, characterized as mostly solid with diffuse spaces, in the location of the right ovary. CA-125 and the lactate dehydrogenase (LDH) tumor markers were elevated. The patient underwent a left salpingo-oophorectomy and pelvic staging. Intra-operative frozen section revealed a dysgerminoma. Final pathology report revealed extensive non-caseating granulomatous inflammation within the ovarian tumor. Special stains showed no evidence of acid-fast organisms. CONCLUSION: Dysgerminoma is the most likely solid ovarian tumor in a patient of this age. In light of her initial renal biopsy with acid-fast bacilli, pelvic tuberculosis needs to be considered. Due to its extreme rarity, sarcoidosis of her genital tract should be lower on the differential, yet this patient presented with pathology consistent with non-caseating granulomas suggesting this diagnosis. Once ovarian dysgerminoma was diagnosed, the possibility that this patient's renal findings may represent paraneoplastic syndrome also becomes important for her treatment.     

The serotonin syndrome—the need for physician’s awareness

Background

Serotonin syndrome is a potentially life-threatening adverse drug reaction that results from therapeutic drug use, usually of selective serotonin reuptake inhibitors (SSRIs), intentional excessive use or interactions between various drugs.

Case presentation

A 16-year-old Caucasian boy presented to our emergency department (ED) with alteration in his mental status for 6 h prior to arrival. On physical examination in our ED, he was combative and disoriented to time, place and person. He was febrile, hypertensive and tachycardic as well. He had intermittent rigid extremities with myoclonus of both lower extremities. A diagnosis of serotonin syndrome (SS) was made based on history of intake of fluoxetine and clinical signs, which included presence of inducible clonus and agitation. The child received supportive care involving intravenous fluids and intravenous lorazepam. The child was back to his baseline mental status and had a normal neurological exam by 24 h and was discharged home later for follow-up with a psychiatrist.

Conclusions

SS occurs with increasing frequency, and most cases resolve with prompt recognition and supportive care. Failure to make an early diagnosis and to comprehend adverse pharmacological effects of therapy can lead to adverse outcomes.     

Influence of skin-to-muscle and muscle-to-bone thickness on depth of needle penetration in adults at the deltoid intramuscular injection site

Background

The objectives of the study were to estimate the following in adults of Indian origin: a) Gender and side differences in the skin-to-muscle (SM) and muscle-to-bone thickness (MB) at the deltoid intramuscular injection site; b) Correlation of SM thickness with the BMI, age and gender; c) The prevalence of under and over-penetration assuming a standard needle length of 25 mm and following prescribed guidelines for IM injection.

Methods

The SM, MB and skin-to-bone (SB) thicknesses were bilaterally estimated in two hundred adult Indian subjects (100 male and 100 female) using an ultrasound probe at a pre-determined point on the upper arms of the subjects. The BMI of each subject was calculated. The unpaired sample ‘t’ test and paired ‘t’ test were used to analyse differences between groups. Pearson''s correlation coefficient was used in correlation analysis and suitable linear regression equations were generated.

Results

Females had a significantly higher SM thickness and lower MB thickness. The SM thickness was significantly greater on the left side, while the SB and MB thickness were significantly greater on the right. Multiple linear regression equations for both the dominant and non-dominant arms had good model fit properties. Under-penetration would have occurred in 2 (1%) subjects while over-penetration would have occurred in 50% of the subjects.

Conclusion

Over-penetration of deltoid IM injections is likely to be more prevalent as compared to under-penetration. Therefore, the technique of IM injection needs to be modified based on the body type of the individual patient.