The Severity and Frequency of Systemic Reactions to Hazelnut Are Significantly Higher in Hazelnut Allergic Patients Monosensitized to Cor a 8 than in Patients Polysensitized to Cor a 1, Cor a 8, and Cor a 9.

INTRODUCTION: Hazelnuts are a leading trigger of food allergy. To date, several molecular components of hazelnut are available for component-resolved diagnosis. However, little is known about how simultaneous sensitization to multiple allergens affects the severity of the hazelnut-induced reaction. In a previous study, our group demonstrated a lower risk of systemic reactions to peach in patients sensitized to both Pru p 3 and Pru p 1 than in the patient monosensitized to peach LTP. We aimed to assess whether this was also true in hazelnut allergy in a cohort of adult patients. METHODS: Patients were selected based on a history of symptoms such as urticaria, vomiting, diarrhea, asthma, and anaphylaxis indicative of hazelnut IgE-mediated food allergy and graded according to a clinical severity scale. For all patients, specific IgE was determined for Cor a 1 and Cor a 8 and, for most patients, also Cor a 9. Patients were offered an oral food challenge in open format (OFC) with a cocoa-based roasted hazelnut spread on a voluntary basis in order to prescribe an appropriate diet. RESULTS: A total of two hundred and fourteen patients were recruited. Among these, 43 patients were monosensitized to Cor a 8. One hundred and seventy-one patients were sensitized to Cor a 1 (79.9%), and, among them, 48/171 (28.1%) were also Cor a 8 positive. Cor a 9 was evaluated in 124/214 patients, testing positive in 21/124 (16.9%). Patients monosensitized to Cor a 8 experienced systemic reactions more frequently than those sensitized to Cor a 1 ± Cor a 8 (p < 0.00001), with significantly more severe reactions (p < 0.0005) and testing more frequently positive at OFC (p < 0.0001). Regarding Cor a 9, the sensitized patients were significantly younger (p = 0.0013) and showed reactions of similar severity to patients who tested Cor a 9 negative, and these reactions were milder than in patients monosensitized only to Cor a 8. DISCUSSION/CONCLUSION: Sensitization to Cor a 1 seems to protect from the development of the severe systemic reactions induced by Cor a 8 sensitization, Cor a 9 does not influence the severity of symptoms in adult patients. The OFC with roasted hazelnut may help in dietary guidance.

Immunotherapy with Pru p 3 for food allergy to peach and non-specific lipid transfer protein: a systematic review.

BACKGROUND: Non-specific lipid-transfer protein (nsLTP) is a pan-allergen in the plant world, and a cause of significant concern as food allergen in the Mediterranean area, due to its general heat- and acid-resistance and hence the risk of severe allergic reactions. Pru p 3, the peach nsLTP, is considered the primary sensitizer to this allergen family and this allergy is usually persistent. Allergen-free diet and acute treatment of manifestations are the main recognized management goals in food allergy. MAIN TEXT: The role of immunotherapy for treating food allergy in adult patients is controversial, but immunotherapy for Pru p 3 could potentially represent a relevant therapeutic strategy. We systematically searched databases for studies assessing the role of immunotherapy Pru p 3 in food allergy. Overall, nine studies were included. Immunotherapy with Pru p 3 appears to be effective and with a good safety profile in both peach and LTP allergy for some foods, such as peanut, in both RCT and real-life studies. CONCLUSIONS: Immunotherapy with Pru p 3 is a possible treatment option for food allergy to the peach LTP in the Mediterranean area, although at present have not reached routinary clinical practice. Larger studies are needed to confirm these findings and identify predictive biomarkers.

Clinical Features of Wheat Allergy Are Significantly Different between Tri a 14 Sensitized Patients and Tri a 19 Sensitized Ones.

INTRODUCTION: Wheat is the most important cereal for human nutrition but its high consumption is associated to an increasing complaint of wheat-related disorders, many of which are allergic in nature and different in respect to the involved allergens. In this study, we compared the clinical aspects of wheat allergy presented by patients sensitized to Tri a 19 in respect to those presented by patients sensitized to Tri a 14. METHODS: With this aim, we selected patients sensitized to 1 or both of the 2 allergens, and among these we identified those who were really wheat allergic and reactive on the basis of a standardized methodology. We evaluated the clinical features such as the kind and severity of symptoms, the coexistence of triggering factors such as physical exercise and NSAIDs and alcohol consumption, and the association with other allergens and with various immunologic parameters. Wheat allergy in Tri a 19 sensitized patients was confirmed through a questionnaire while the patients sensitized to Tri a 14 underwent wheat challenge with 100 g of pasta followed by exercise on a treadmill. RESULTS: Seventy-nine patients sensitized to Tri a 14 and 40 patients sensitized to Tri a 19 were recruited. The 2 sensitizations were independent with a significant inverse relation (p < 0.00001). The Tri a 19 sensitized patients presented, in respect to the Tri a 14 sensitized ones, an older age (p = 0.0017), a higher risk to be wheat allergic (p < 0.0001), a higher severity of the reactions (p < 0.00001) and a higher association with some cofactors, namely alcohol (p < 0.0005) and physical exercise (p = 0.003). On the contrary, Tri a 14 sensitization was associated with atopy (p < 0.0001), with a higher probability of patients being asymptomatic (p < 0.0001) and being sensitized to other foods, in particular to nuts and cereals (p < 0.00001). CONCLUSIONS: Sensitization to Tri a 19 or Tri a 14 determines different clinical pictures. In particular, sensitization to Tri a 19 implies a higher probability of severe reactions, even dependent on daily triggers, while that to Tri a 14 implies a higher cross-reactivity with other foods but it's more frequently asymptomatic, making a food challenge necessary to prevent useless food avoidance.

Basal Tryptase High Levels Associated with a History of Arterial Hypertension and Hypercholesterolemia Represent Risk Factors for Severe Anaphylaxis in Hymenoptera Venom-Allergic Subjects over 50 Years Old.

INTRODUCTION: Allergy to Hymenoptera venom (HV) may lead to life-threatening anaphylaxis. Some of the factors influencing the symptom's severity are still undetermined. The aim of this study was to identify the clinical aspects associated with the most severe reactions in a population with HV allergy, by comparing clinical and immunochemical biomarkers between patients with previous local large reactions (LLRs) and systemic reactions (SRs). METHODS: We selected adult patients with a history of HV allergy, with positive diagnostic tests and a correlation with one single Hymenoptera species. Age, gender, atopy, serum basal tryptase (sBT) value, total IgE, venom-specific IgE, history of hypertension, cardiovascular diseases, and hypercholesterolemia were compared between patients with previous LLRs and SRs. RESULTS: 460 adult patients (381 SRs, 79 LLRs) were included. Age (p = 0.0097), male gender (p < 0.0001), arterial hypertension (p = 0.046), hypercholesterolemia (p = 0.009), and higher sBT levels (p = 0.0004) were significantly associated with severe reactions as independent variables. Moreover, considering the previous variables as risk factors, there was a significant and progressive increase in the odds of being Mueller III + IV as the number of positive variables increased. Patients with sBT ≥6.4 ng/mL adjusted for any of the positive variables had increased the risk of Mueller grade IV reaction (p < 0.0001). CONCLUSION: According to our results, older age, male gender, arterial hypertension, hypercholesterolemia, and increased levels of sBT ≥6.4 ng/mL are risk factors for severe anaphylaxis to HV in adults. Atopy and allergic asthma do not increase the risk of HV-induced SRs.

A case report of toxic epidermal necrolysis (TEN) in a patient with COVID-19 treated with hydroxychloroquine: are these two partners in crime?

BACKGROUND: Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis (SJS/TEN) is the most Serious Cutaneous Adverse Reaction (SCAR) often with a fatal outcome. Coronavirus Disease (COVID-19) is caused by Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-COV2) and is an emergent pandemic for which no cure exist at the moment. Several drugs have been tried often with scant clinical evidence and safety. CASE PRESENTATION: Here we report the case of 78-years-old woman with cardiometabolic syndrome and COVID-19. A multidrug regimen including others hydroxychloroquine, antibiotics, dexamethasone and paracetamol, low-molecular-weight-heparin and potassium canrenoate was started. After almost 3 weeks, the patient started to display a violaceous rash initially involving the flexural folds atypical targetoid lesions and showing a very fast extension, blister formation and skin detachments of approximately 70% of the total body surface area and mucous membranes involvement consistent with toxic epidermal necrolysis (TEN). The ALDEN algorithm was calculated inserting all drugs given to the patient in the 28 days preceding the onset of the skin manifestations. The highest score retrieved was for hydroxychloroquine. Other less suspicious drugs were piperacillin/tazobactam, ceftriaxone and levofloxacin. CONCLUSIONS: To our knowledge, this is the first case of TEN in a patient suffering from COVID-19 probably associated with hydroxychloroquine. Given the activation of the immune system syndrome induced by the virus and the widespread off-label use of this drug, we suggest a careful monitoring of skin and mucous membranes in all COVID-19 positive patients treated with hydroxychloroquine in order to early detect early signs of toxicities.

Eosinophilic esophagitis in the era of biologics.

INTRODUCTION: Eosinophilic esophagitis (EoE) is a chronic inflammatory, disabling disorder characterized by prominent eosinophilic inflammation of the esophagus, leading to troublesome symptoms including dysphagia and food impaction. The natural history of EoE is poorly known, but it may lead to esophageal strictures. The therapeutic armamentarium is expected to grow in the near future, especially due to the availability of novel biological therapies targeting crucial inflammatory pathways of EoE. AREAS COVERED: In this review, we discuss the main clinical features and natural history of EoE, focusing on the current therapeutic strategies, as well as past and current trials investigating biologics for its treatment. EXPERT OPINION: Dupilumab has been the first approved biologic drug for the treatment of EoE; long-term studies assessing how it could change the natural history of EoE are awaited. Novel biological drugs or other molecules are currently under study and could change the current treatment algorithms in the near future. Proper drug positioning and long term 'exit strategies' are yet to be defined.

Diagnosis, management and therapeutic options for eosinophilic esophagitis.

PURPOSE OF REVIEW: Eosinophilic esophagitis is a chronic and commonly evolving condition leading to relevant and potentially irreversible burden in terms of tissue damage and related functional impairment, thus significantly impacting on quality of life. The aim of the present review is to summarize the recent advances in terms of diagnostic work-up and pharmacological and nonpharmacological management of the disease, under the broader perspective of type 2 inflammation. RECENT FINDINGS: Two major novelties have prompted an innovative approach to EoE. In terms of diagnosis, it has been proposed to dissect the disease heterogeneity in three endotypes, independent from tissue eosinophil number: EoEe1, characterized by normal appearing oesophagus; EoEe2, associated with type 2 inflammation and steroid-refractoriness; EoEe3, whose features include adult onset, a more fibro-stenotic aspect and loss of epithelial gene expression. Concerning treatment, two recently licensed drugs for EoE, oro-dispersible budesonide and dupilumab represent the first treatment options specifically developed for EoE and addressing EoE-related peculiar pathobiological features. SUMMARY: In the era of precision medicine, managing EoE according to a phenotype-driven approach might be helpful in defining the best treatment options in the different disease forms or stages. In addition, exploring the coexistence or the previous occurrence of other type 2 conditions may suggest the opportunity to specifically target type 2 inflammation through biologic therapy. The complex EoE pathobiology combining inflammatory and functional features, both at organ and systemic level, requires a multidimensional approach relying on the strict integration of gastroenterologists and allergist-immunologists.

Haematological sequelae in the post-acute phase of symptomatic SARS-CoV-2 infection.

Many patients surviving SARS-CoV-2 infection suffer from long-term symptoms (long COVID or post COVID) such as shortness of breath, fatigue, loss of taste or smell and cognitive deterioration. However, few data are available concerning blood cell counts and haematological parameters during the post-COVID period. We analysed haematological data from 83 patients previously admitted to the internal medicine unit of our institution because of symptomatic SARS-CoV-2 infection; all data were obtained within 1-12 months from disease onset. A control group of 70 apparently healthy, age- and sex-matched COVID-19 negative individuals was assessed for comparison. Blood cell counts improved in the post-COVID period, but 81% of patients had persistent abnormalities, compared with 50% in the control group, p < 0.001. Most common haematological findings included anaemia (40%), reduced lymphocyte (43%) or eosinophil counts (38%) and low IgM memory B cells and correlated with advanced age, number of chronic comorbidities, female gender, altered renal function, reduced baseline Hb and procalcitonin concentrations and increased RDW. Data on lymphocytes and IgM memory B cells show that impaired immune responses may persist for up to one year in the post-COVID period, possibly contributing to long-term symptoms, especially in female patients.

Recent advances in intestinal fibrosis.

Despite many progresses have been made in the treatment of inflammatory bowel disease, especially due to the increasing number of effective therapies, the development of tissue fibrosis is a very common occurrence along the natural history of this condition. To a certain extent, fibrogenesis is a physiological and necessary process in all those conditions characterised by chronic inflammation. However, the excessive deposition of extracellular matrix within the bowel wall will end up in the formation of strictures, with the consequent need for surgery. A number of mechanisms have been described in this process, but some of them are not yet clear. For sure, the main trigger is the presence of a persistent inflammatory status within the mucosa, which in turn favours the occurrence of a pro-fibrogenic environment. Among the main key players, myofibroblasts, fibroblasts, immune cells, growth factors and cytokines must be mentioned. Although there are no available therapies able to target fibrosis, the only way to prevent it is by controlling inflammation. In this review, we summarize the state of art of the mechanisms involved in gut fibrogenesis, how to diagnose it, and which potential targets could be druggable to tackle fibrosis.

Clinical and atopic features of patients with primary eosinophilic colitis: an Italian multicentre study.

Eosinophilic colitis (EC) is the rarest among primary eosinophilic gastrointestinal disorders (EGID). EC is underdiagnosed due to its blurred and proteiform clinical manifestations. To explore the clinical and atopic characteristic of EC adult patients, the diagnostic delay, and relapse-associated factors, by comparison with patients with eosinophilic esophagitis (EoE) and irritable bowel syndrome (IBS). EC patients followed-up at four clinics were included, and clinical, histopathological, and laboratory data were retrieved. As control groups, age-matched patients with EoE and IBS were recruited. Allergy tests included skin prick test and serum specific IgE. Diagnostic delay was assessed. Overall, data from 73 patients were retrieved, including 40 with EC (median age 39 years IQR 22.5-59, F:M 2.1:1), 12 with EoE (F:M ratio: 1:5), and 21 with IBS (F:M ratio: 1:0.9). The most common features in EC patients were female sex (67.5%), atopy (77.5%), abdominal pain/distention (70%), diarrhoea (77.5%), and faecal calprotectin elevation (22.5%). Blood eosinophils were elevated in EoE, but not in EC (p < 0.001), while ECP did not differ across the three groups (p = 0.4). The frequency of allergen sensitization reached 25% of patients. Several frequent pan-allergens for this region were present. The overall diagnostic delay was 10 months (IQR 4-15). Factors contributing to a greater diagnostic delay were atopy, weight loss, and a previous misdiagnosis. EC is mostly a diagnosis of exclusion, burdened by a substantial diagnostic delay. In female patients the presence of allergen sensitization, abdominal symptoms and faecal calprotectin elevation should raise the suspicion of EC.

Diagnostic delay in symptomatic uncomplicated diverticular disease: an Italian tertiary referral centre study.

The magnitude of the diagnostic delay of symptomatic uncomplicated diverticular disease (SUDD) is unknown; we aimed to evaluate SUDD diagnostic delay and its risk factors. SUDD patients diagnosed at a tertiary referral centre were retrospectively enrolled (2010-2022). Demographic and clinical data were retrieved. Overall, patient-, and physician-dependant diagnostic delays were assessed. Univariate and multivariate analyses were fitted to identify risk factors for diagnostic delay. Overall, 70 SUDD patients (median age 65 years, IQR 52-74; F:M ratio = 1.6:1) were assessed. The median overall diagnostic delay was 7 months (IQR 2-24), patient-dependant delay was 3 months (IQR 0-15), and physician-dependant delay was 1 month (IQR 0-6). Further, 25% of patients were misdiagnosed with irritable bowel syndrome (IBS). At multivariate analysis, previous misdiagnosis was a significant risk factor for overall and physician-dependant diagnostic delay (OR 9.99, p = 0.01, and OR 6.46, p = 0.02, respectively). Also, a high educational level (> 13 years) was associated with a greater overall diagnostic delay (OR 8.74 p = 0.02), while previous abdominal surgery was significantly associated to reduced physician-dependant diagnostic delay (OR 0.19 p = 0.04). To conclude, SUDD may be diagnosed late, IBS being the most frequent misdiagnosis. Timely diagnosis is crucial to tackle the burden of SUDD on patients and healthcare.

Diagnostic Delay of Celiac Disease in Childhood.

Importance: The extent and factors associated with risk of diagnostic delay in pediatric celiac disease (CD) are poorly understood. Objectives: To investigate the diagnostic delay of CD in childhood, and to assess factors associated with this delay. Design, Setting, and Participants: Multicenter, retrospective, cross-sectional study (2010-2019) of pediatric (aged 0-18 years) patients with CD from 13 pediatric tertiary referral centers in Italy. Data were analyzed from January to June 2023. Main Outcomes and Measures: The overall diagnostic delay (ie, the time lapse occurring from the first symptoms or clinical data indicative of CD and the definitive diagnosis), further split into preconsultation and postconsultation diagnostic delay, were described. Univariable and multivariable linear regression models for factors associated with diagnostic delay were fitted. Factors associated with extreme diagnostic delay (ie, 1.5 × 75th percentile) and misdiagnosis were assessed. Results: A total of 3171 patients with CD were included. The mean (SD) age was 6.2 (3.9) years; 2010 patients (63.4%) were female; and 10 patients (0.3%) were Asian, 41 (1.3%) were Northern African, and 3115 (98.3%) were White. The median (IQR) overall diagnostic delay was 5 (2-11) months, and preconsultation and postconsultation diagnostic delay were 2 (0-6) months and 1 (0-3) month, respectively. The median (IQR) extreme overall diagnostic delay (586 cases [18.5%]) was 11 (5-131) months, and the preconsultation and postconsultation delays were 6 (2-120) and 3 (1-131) months, respectively. Patients who had a first diagnosis when aged less than 3 years (650 patients [20.5%]) showed a shorter diagnostic delay, both overall (median [IQR], 4 [1-7] months for patients aged less than 3 years vs 5 [2-12] months for others) and postconsultation (median [IQR], 1 [0-2] month for patients aged less than 3 years vs 2 [0-4] months for others). A shorter delay was registered in male patients, both overall (median [IQR], 4 [1-10] months for male patients vs 5 [2-12] months for female patients) and preconsultation (median [IQR], 1 [0-6] month for male patients vs 2 [0-6] months for female patients). Family history of CD was associated with lower preconsultation delay (odds ratio [OR], 0.59; 95% CI, 0.47-0.74) and lower overall extreme diagnostic delay (OR, 0.75; 95% CI, 0.56-0.99). Neurological symptoms (78 patients [21.5%]; OR, 1.35; 95% CI, 1.03-1.78), gastroesophageal reflux (9 patients [28.1%]; OR, 1.87; 95% CI, 1.02-3.42), and failure to thrive (215 patients [22.6%]; OR, 1.62; 95% CI, 1.31-2.00) showed a more frequent extreme diagnostic delay. A previous misdiagnosis (124 patients [4.0%]) was more frequently associated with gastroesophageal reflux disease, diarrhea, bloating, abdominal pain, constipation, fatigue, osteopenia, and villous atrophy (Marsh 3 classification). Conclusions and Relevance: In this cross-sectional study of pediatric CD, the diagnostic delay was rather short. Some factors associated with risk for longer diagnostic delay and misdiagnosis emerged, and these should be addressed in future studies.

Role of mucosal immunity and epithelial-vascular barrier in modulating gut homeostasis.

The intestinal mucosa represents the most extensive human barrier having a defense function against microbial and food antigens. This barrier is represented externally by a mucus layer, consisting mainly of mucins, antimicrobial peptides, and secretory immunoglobulin A (sIgA), which serves as the first interaction with the intestinal microbiota. Below is placed the epithelial monolayer, comprising enterocytes and specialized cells, such as goblet cells, Paneth cells, enterochromaffin cells, and others, each with a specific protective, endocrine, or immune function. This layer interacts with both the luminal environment and the underlying lamina propria, where mucosal immunity processes primarily take place. Specifically, the interaction between the microbiota and an intact mucosal barrier results in the activation of tolerogenic processes, mainly mediated by FOXP3+ regulatory T cells, underlying intestinal homeostasis. Conversely, the impairment of the mucosal barrier function, the alteration of the normal luminal microbiota composition (dysbiosis), or the imbalance between pro- and anti-inflammatory mucosal factors may result in inflammation and disease. Another crucial component of the intestinal barrier is the gut-vascular barrier, formed by endothelial cells, pericytes, and glial cells, which regulates the passage of molecules into the bloodstream. The aim of this review is to examine the various components of the intestinal barrier, assessing their interaction with the mucosal immune system, and focus on the immunological processes underlying homeostasis or inflammation.

Dietary Strategies in Adult Patients with Eosinophilic Esophagitis: A State-of-the-Art Review.

Allergen-free diets are a specific and effective anti-inflammatory therapy for eosinophilic esophagitis. They should be carried out by a multidisciplinary team to reduce side effects and improve adherence. According to recent guidelines and expert opinions, empirical diets with a reduced number of eliminated food categories and a step-up approach are the most encouraged strategy to reduce the number of endoscopies to identify food trigger(s) and maximize clinical results and adherence. Despite the fact that allergy testing-based diets are not recommended at a population level, geographical sensitization patterns may play a role in some patients in specific areas, such as in Southern and Central Europe.

Diagnostic delay in adult coeliac disease: An Italian multicentre study.

BACKGROUND: There are few data regarding the diagnostic delay and its predisposing factors in coeliac disease (CD). AIMS: To investigate the overall, the patient-dependant, and the physician-dependant diagnostic delays in CD. METHODS: CD adult patients were retrospectively enroled at 19 Italian CD outpatient clinics (2011-2021). Overall, patient-dependant, and physician-dependant diagnostic delays were assessed. Extreme diagnostic, i.e., lying above the third quartile of our population, was also analysed. Multivariable regression models for factors affecting the delay were fitted. RESULTS: Overall, 2362 CD patients (median age at diagnosis 38 years, IQR 27-46; M:F ratio=1:3) were included. The median overall diagnostic delay was 8 months (IQR 5-14), while patient- and physician-dependant delays were 3 (IQR 2-6) and 4 (IQR 2-6) months, respectively. Previous misdiagnosis was associated with greater physician-dependant (1.076, p = 0.005) and overall (0.659, p = 0.001) diagnostic delays. Neurological symptoms (odds ratio 2.311, p = 0.005) and a previous misdiagnosis (coefficient 9.807, p = 0.000) were associated with a greater extreme physician-dependant delay. Gastrointestinal symptoms (OR 1.880, p = 0.004), neurological symptoms (OR 2.313, p = 0.042), and previous misdiagnosis (OR 4.265, p = 0.000) were associated with increased extreme overall diagnostic delay. CONCLUSION: We identified some factors that hamper CD diagnosis. A proper screening strategy for CD should be implemented.

Adult anaphylaxis: A state-of-the-art review.

Anaphylaxis is the most severe among acute allergic diseases and potentially life threatening. Despite its increasing frequency and related burden, it remains often underdiagnosed and improperly managed. Its multisystemic involvement, protean clinical manifestations and its rapid onset are contributory factors. In recent years new acquisitions have shed light into its pathogenesis pathways (and related biomarkers), triggers, factors increasing its severity, along with peculiar clinical manifestations. These breakthrough discoveries have contributed to phenotyping and endotyping this disease, possibly paving the way to a personalized approach which is not available at present. Moreover, to disseminate awareness and standardize diagnostic criteria and management practices, several guidelines and consensus reports, albeit mainly intended for specialist care, have been issued. We here discuss the latest issues in the field of anaphylaxis from the perspective of the emergency and/or internal medicine physician, so to improve its early recognition and treatment in the acute setting and favor allergology referral to implement therapeutical and preventive strategies, such as allergen identification in unclear cases and desensitizing therapies when available (e.g., for Hymenoptera venom allergy).

Role of IgM Memory B Cells and Spleen Function in COVID-19.

IgM memory B cells, are a peculiar subset of memory B cells, which probably originates in the spleen and outside germinal centers and provide a rapid line of defence against mucosal infections. Their role in counteracting COVID-19 is still elusive but, recent evidence, mainly boosted by studies on spleen function/involvement in COVID-19, seems to support the notion that this subset of memory B cells could exert a protective role against this virus, along with other coronaviruses, particularly in the acute setting of the infection, as outlined by worst clinical outcomes observed in unvaccinated patients with impaired IgM B memory response and spleen function. Herein we critically summarise the current landscape of studies on IgM memory B cells, focusing on the clinical impact of their depletion, by comparing the COVID-19-related splenic dysfunction with other hypo- and asplenic conditions and by adding recent data on follow-up studies and postulate a mechanistic explanation for their reduced numbers. The early detection of an impaired IgM memory B cell response in patients with COVID-19 may contribute to their improved care through different strategies, such as through tailored vaccine strategies, prompt hospital admission and/or administration of anti-infective treatments, thus resulting in an better prognosis, although at present management algorithms are still unavailable. Moreover, further studies with longer follow-up are needed to assess the evolution of COVID-19-associated/exacerbated immune deficit.

Allergic manifestations in autoimmune gastrointestinal disorders.

Allergic disorders target a young population, are increasing in both incidence and prevalence and are associated with significant disease burden. They result from the complex interplay between (epi)genetic and environmental factors, resulting in a Th2 inflammatory process targeting the epithelium of the respiratory tract (allergic rhinitis and asthma), skin (atopic dermatitis), and gastrointestinal tract (food allergy). Although the exact pathogenic mechanisms remain elusive, an altered immune system response in the gut is increasingly recognized as a relevant step. Allergic and gastrointestinal autoimmune disorders share several epidemiological, pathogenic and risk factors and several treatment modalities. Here we revise the current literature and show that allergic disorders are highly prevalent in gastrointestinal autoimmune diseases, including celiac disease, inflammatory bowel disease, autoimmune pancreatitis, and autoimmune cholangiopathies. No data are available for some autoimmune diseases, such as autoimmune gastritis and autoimmune enteropathy. To ensure the comprehensive care of patients with autoimmune gastrointestinal disorders, along with disease-specific factors, the presence of allergic disorders should be evaluated and treated when present, possibly targeting shared molecular pathways. Future studies are needed to define the exact pathogenic mechanisms underpinning the association between allergic and autoimmune diseases of the gastrointestinal tract.