Cimetidine enhances antigen-specific IgE and Th2 cytokine production

Prenatal and Infant Exposure to Acid-Suppressive Medications and Risk of Allergic Diseases in Children

Importance

Existing observational data have indicated positive associations of acid-suppressive medication (ASM) use in prenatal and early life with allergic diseases in children; however, no study to date has accounted for confounding by indication or within-familial factors.

Objective

To evaluate the association of prenatal or infant exposure to ASMs with risk of allergic diseases in children.

Design, Setting, and Participants

This nationwide, cohort study included data from South Korea's National Health Insurance Service mother-child-linked database from January 1, 2007, to December 31, 2020. Participants included mother-child pairs of neonates born from April 1, 2008, to December 31, 2019.

Exposures

Prenatal and infant exposure to ASMs (histamine 2 receptor antagonists [H2RAs] and proton pump inhibitors [PPIs]).

Main Outcomes and Measures

Composite and individual outcomes of allergic diseases (asthma, allergic rhinitis, atopic dermatitis, and food allergy) in children (followed up to 13 years of age) were assessed. The ASM-exposed individuals were compared with unexposed individuals in propensity score (PS)-matched and sibling-matched analyses to control for various potential confounders and within-familial factors. Hazard ratios (HRs) with 95% CIs were estimated using Cox proportional hazards regression models.

Results

The study included 4 149 257 mother-child pairs. Prenatal exposure analyses included 808 067 PS-matched pairs (763 755 received H2RAs, 36 529 received PPIs) among women with a mean (SD) age of 31.8 (4.2) years. The PS-matched HR was 1.01 (95% CI, 1.01-1.02) for allergic diseases overall (asthma: HR, 1.02 [95% CI, 1.01-1.03]; allergic rhinitis: HR, 1.02 [95% CI, 1.01-1.02]; atopic dermatitis: HR, 1.02 [95% CI, 1.01-1.02]; food allergy: HR, 1.03 [95% CI, 0.98-1.07]); in sibling-matched analyses, the HRs were similar to those of PS-matched analyses but were not significant (allergic diseases: HR, 1.01; 95% CI, 0.997-1.01). Infant exposure analyses included 84 263 PS-matched pairs (74 188 received H2RAs, 7496 received PPIs). The PS-matched HR was 1.06 (95% CI, 1.05-1.07) for allergic diseases overall (asthma: HR, 1.16 [95% CI, 1.14-1.18]; allergic rhinitis: HR, 1.02 [95% CI, 1.01-1.03]; atopic dermatitis: HR, 1.05 [95% CI, 1.02-1.08]; food allergy: HR, 1.28 [95% CI, 1.10-1.49]); asthma risk (HR, 1.13; 95% CI, 1.09-1.17) remained significantly higher among children exposed to ASMs during infancy in sibling-matched analyses. The findings were similar for H2RAs and PPIs analyzed separately and were robust across all sensitivity analyses.

Conclusions and Relevance

The findings of this cohort study suggest that there is no association between prenatal exposure to ASMs and allergic diseases in offspring. However, infant exposure to ASMs was associated with a higher risk of developing asthma, although the magnitude was more modest than previously reported. Clinicians should carefully weigh the benefits of prescribing ASMs to children, accompanied by subsequent close monitoring for any clinically relevant safety signals.

Potential Allergenicity Response to Moringa oleifera Leaf Proteins in BALB/c Mice

The reported association of Moringa oleifera seeds and allergic disease clinically resembling occupational asthma in cosmetic manufacturing workers has resultedin the need to identify such components in the manufacturing process. However, Moringa oleifera leaves from the same plant, an important food ingredient, have limited immunotoxicity data. This study aimed to determine if Moringa oleifera leafproteins (MLP) can elicit allergic responses in BALB/c mice. The BALB/c mice were sensitized twice and challenged 10 times to evaluate the potential allergenicityof MLP in vivo. The results showed increased levels of mast cells, total and specific IgE and IgG, severe signs of systemic anaphylaxis, and reduced body temperature compared with controls. The sensitized mice serum observed enhanced levels of histamine and Th-related cytokine release. Compared with the control group, increased levels of interleukins IL-4, IL-9, and IL-17A and enhanced expression and secretion of normal T cells were found in the culture supernatant of splenocytes treated with MLP.This study suggeststhat MLPcanelicit allergic responses; this providesmore comprehensive guidance for identifying new allergen candidates and developing hypoallergenic MLP products.

Effectiveness of Cimetidine as Adjuvant Therapy in the Treatment of Acute-Extrinsic Atopic Dermatitis: A Double-Blind Randomized Controlled Trial

Introduction

Acute extrinsic atopic dermatitis (AD) requires long-term treatment. Cimetidine could be used as an adjuvant therapy for acute-extrinsic AD due to immunomodulatory effects. This study aims to assess the effectiveness of cimetidine as an adjuvant to standard treatment in acute extrinsic AD.

Methods

This is a double-blind randomized controlled trial involving 26 AD patients aged 12–60 years from 2017 to 2020. Effectiveness of cimetidine was assessed by comparing SCORing Atopic Dermatitis (SCORAD) and objective SCORAD changes in both groups at week 2, 4, 6, and 8. Serum levels of immunoglobulin E (IgE), interferon (IFN)-γ, interleukin (IL)-12, and IL-4 were also documented.

Results

Significant differences were observed in SCORAD changes at week 2, 4, 6, and 8 (p = 0.004; p = 0.001; p < 0.001; and p < 0.001 respectively), objective SCORAD changes at week 2, 4, 6, and 8 (p = 0.004, p = 0.001, p < 0.001, and p < 0.001 respectively), and IgE level changes at week 8 (p = 0.002) between the two groups. However, there were no significant changes in IFN-γ, IL-12, and IL-4 levels between the two groups.

Conclusion

Cimetidine is a safe and effective adjuvant therapy for acute-extrinsic AD.

Trial Registration

NCT04018131.

H2-antagonist in IgE-mediated type I hypersensitivity reactions: what literature says so far?

Histamine is a monoamine synthesized from the amino acid histidine that is well-known for its role in IgE-mediated anaphylaxis but has shown pleiotropic effects on the immune system, especially in order to promote inflammatory responses. H₁-receptor antagonist are common drugs used in mild/moderate allergic reactions whereas H₂-receptor antagonist are commonly administered in gastric ulcer but showed some properties in allergy too. The EAACI guidelines for diagnosis and treatment of anaphylactic reactions recommend their use as third-line therapy in adjunct to H₁-antagonists. The purpose of this article is to produce a complete summary of findings and evidence known so far about the usefulness of H₂-receptor antagonist in allergic reactons.

Urticaria and the gut

PURPOSE OF REVIEW

To review recent evidence on the association of urticaria and the gut diseases, focusing on the roles of chronic inflammation with or without Helicobacter pylori (H. Pylori) infection.

RECENT FINDINGS

The connection between the gut and urticaria has been discussed for a long time. Some publications have shown that H. pylori can induce chronic spontaneous urticaria (CSU). Recently, it was reported that upper gastrointestinal inflammatory disorders can cause CSU and trigger exacerbations independently of H. pylori.

SUMMARY

Gastritis and especially H. pylori-induced gastritis has been implicated as potential trigger of CSU. Chronic parasite infection and inflammation of the gut are relevant comorbidities and also potential inducing factors for the development of urticaria.

Country-wide medical records infer increased allergy risk of gastric acid inhibition

Gastric acid suppression promotes allergy in mechanistic animal experiments and observational human studies, but whether gastric acid inhibitors increase allergy incidence at a population level remains uncharacterized. Here we aim to assess the use of anti-allergic medication following prescription of gastric acid inhibitors. We analyze data from health insurance records covering 97% of Austrian population between 2009 and 2013 on prescriptions of gastric acid inhibitors, anti-allergic drugs, or other commonly prescribed (lipid-modifying and antihypertensive) drugs as controls. Here we show that rate ratios for anti-allergic following gastric acid-inhibiting drug prescriptions are 1.96 (95%CI:1.95–1.97) and 3.07 (95%-CI:2.89–3.27) in an overall and regional Austrian dataset. These findings are more prominent in women and occur for all assessed gastric acid-inhibiting substances. Rate ratios increase from 1.47 (95%CI:1.45–1.49) in subjects <20 years, to 5.20 (95%-CI:5.15–5.25) in > 60 year olds. We report an epidemiologic relationship between gastric acid-suppression and development of allergic symptoms.

Gastric acid inhibitors promote experimental allergy in animals, and have been linked to allergy risk in observational human studies. Here the authors show in a country-wide medical record analysis that allergy development risk is doubled in gastric acid inhibitor users, and is higher in women and in older age.

Immunomodulatory properties of cimetidine: Its therapeutic potentials for treatment of immune-related diseases

Histamine exerts potent modulatory impacts on the cells of innate- [including neutrophils, monocytes, macrophages, dendritic cells (DCs), natural killer (NK) cells and NKT cells] and adaptive immunity (such as Th1-, Th2-, Th17-, regulatory T-, CD8⁺ cytotoxic T cells, and B cells) through binding to histamine receptor 2 (H2R). Cimetidine, as an H2R antagonist, reverses the histamine-mediated immunosuppression, as it has powerful stimulatory effects on the effector functions of neutrophils, monocytes, macrophages, DCs, NK cells, NKT cells, Th1-, Th2-, Th17-, and CD8⁺ cytotoxic T cells. However, cimetidine reduces the regulatory/suppressor T cell-mediated immunosuppression. Experimentally, cimetidine potentiate some immunologic activities in vitro and in vivo. The therapeutic potentials of cimetidine as an immunomodulatory agent were also investigated in a number of human diseases (such as cancers, viral warts, allergic disorders, burn, and bone resorption) and vaccination. This review aimed to provide a concise summary regarding the impacts of cimetidine on the immune system and highlight the cellular mechanisms of action and the immunomodulatory effects of this drug in various diseases to give novel insights regarding the therapeutic potentials of this drug for treatment of immune-related disorders. The review encourages more investigations to consider the immunomodulatory characteristic of cimetidine for managing of immune-related disorders.

Association Between Use of Acid-Suppressive Medications and Antibiotics During Infancy and Allergic Diseases in Early Childhood

IMPORTANCE

Allergic diseases are prevalent in childhood. Early exposure to medications that can alter the microbiome, including acid-suppressive medications and antibiotics, may influence the likelihood of allergy.

OBJECTIVE

To determine whether there is an association between the use of acid-suppressive medications or antibiotics in the first 6 months of infancy and development of allergic diseases in early childhood.

DESIGN, SETTING, AND PARTICIPANTS

A retrospective cohort study was conducted in 792 130 children who were Department of Defense TRICARE beneficiaries with a birth medical record in the Military Health System database between October 1, 2001, and September 30, 2013, with continued enrollment from within 35 days of birth until at least age 1 year. Children who had an initial birth stay of greater than 7 days or were diagnosed with any of the outcome allergic conditions within the first 6 months of life were excluded from the study. Data analysis was performed from April 15, 2015, to January 4, 2018.

EXPOSURES

Exposures were defined as having any dispensed prescription for a histamine-2 receptor antagonist (H2RA), proton pump inhibitor (PPI), or antibiotic.

MAIN OUTCOMES AND MEASURES

The main outcome was allergic disease, defined as the presence of food allergy, anaphylaxis, asthma, atopic dermatitis, allergic rhinitis, allergic conjunctivitis, urticaria, contact dermatitis, medication allergy, or other allergy.

RESULTS

Of 792 130 children (395 215 [49.9%] girls) included for analysis, 60 209 (7.6%) were prescribed an H2RA, 13 687 (1.7%) were prescribed a PPI, and 131 708 (16.6%) were prescribed an antibiotic during the first 6 months of life. Data for each child were available for a median of 4.6 years. Adjusted hazard ratios (aHRs) in children prescribed H2RAs and PPIs, respectively, were 2.18 (95% CI, 2.04-2.33) and 2.59 (95% CI, 2.25-3.00) for food allergy, 1.70 (95% CI, 1.60-1.80) and 1.84 (95% CI, 1.56-2.17) for medication allergy, 1.51 (95% CI, 1.38-1.66) and 1.45 (95% CI, 1.22-1.73) for anaphylaxis, 1.50 (95% CI, 1.46-1.54) and 1.44 (95% CI, 1.36-1.52) for allergic rhinitis, and 1.25 (95% CI, 1.21-1.29) and 1.41 (95% CI, 1.31-1.52) for asthma. The aHRs after antibiotic prescription in the first 6 months of life were 2.09 (95% CI, 2.05-2.13) for asthma, 1.75 (95% CI, 1.72-1.78) for allergic rhinitis, 1.51 (95% CI, 1.38-1.66) for anaphylaxis, and 1.42 (95% CI, 1.34-1.50) for allergic conjunctivitis.

CONCLUSIONS AND RELEVANCE

This study found associations between the use of acid-suppressive medications and antibiotics during the first 6 months of infancy and subsequent development of allergic disease. Acid-suppressive medications and antibiotics should be used during infancy only in situations of clear clinical benefit.

Development of a BALB/c mouse model for food allergy: comparison of allergy-related responses to peanut agglutinin, β-lactoglobulin and potato acid phosphatase

The purpose of this study was to develop a BALB/c mouse model for comprehensively assessing food allergies. Serum specific IgE and IgG1 antibodies against protein (PNA, β-LG, and PAP) were induced in intraperitoneally sensitized BALB/c mice. On day 28, blood was collected to obtain the serum, and the splenocytes were cultured. On day 30, mice were challenged with antigen by intraperitoneal injection or intragastric administration, and the physiological and immunological responses to the antigen were studied. A general finding was that allergenicity-related parameters in the mice treated with PNA were statistically higher than those in the mice treated with PAP (P < 0.05 for IL-4; P < 0.05 for specific IgE; P < 0.001 for specific IgG1), whereas parameters in those treated with β-LG were between the other two. Statistically higher histamine release was observed in PNA and β-LG-sensitized mice than in control mice challenged with the same protein by i.p. injection. Intraperitoneal challenge with PNA and β-LG in sensitized mice induced edema in the ear and inflammatory cell infiltration in the lung, which were not observed with the control mice. The results show a new model that covers many features of clinical food allergies that are not seen in other models. The order of potential allergenicity might be PNA > β-LG > PAP, and the intraperitoneal challenge could be more sensitive to induced systemic food allergy.

Radioprotective effects of cimetidine on rats irradiated by long-term, low-dose-rate neutrons and 60Co γ-rays

BACKGROUND

Cimetidine, an antagonist of histamine type II receptors, has shown protective effects against γ-rays or neutrons. However, there have been no reports on the effects of cimetidine against neutrons combined with γ-rays. This study was carried out to evaluate the protective effects of cimetidine on rats exposed to long-term, low-dose-rate neutron and γ-ray combined irradiation (n-γ LDR).

METHODS

Fifty male Sprague-Dawley (SD) rats were randomly divided into 5 groups: the normal control group, radiation model group, 20 mg/(kg · d) cimetidine group, 80 mg/(kg · d) cimetidine group and 160 mg/(kg · d) cimetidine group (10 rats per group). Except for the normal control group, 40 rats were simultaneously exposed to fission neutrons (²⁵²Cf, 0.085 mGy/h) for 22 h every day and γ-rays (⁶⁰Co, 0.097 Gy/h) for 1.03 h once every three days, and the cimetidine groups were administered intragastrically with cimetidine at doses of 20, 80 and 160 mg/kg each day. Peripheral blood WBC of the rats was counted the day following exposure to γ-rays. The rats were anesthetized and sacrificed on the day following exposure to ²⁵²Cf for 28 days. The spleen, thymus, testicle, liver and intestinal tract indexes were evaluated. The DNA content of bone marrow cells and concanavalin A (ConA)-induced lymphocyte proliferation were measured. The frequency of micronuclei in polychromatic erythrocytes (fMNPCEs), superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione peroxidase (GSH-Px) in the serum and liver tissues were detected.

RESULTS

The peripheral blood WBC in the cimetidine groups was increased significantly on the 8th day and the 26th day compared with those in the radiation model group. The spleen, thymus and testicle indexes of the cimetidine groups were higher than those of the radiation model group. The DNA content of bone marrow cells and lymphocyte proliferation in the cimetidine groups were increased significantly, and fMNPCE was reduced 1.41-1.77 fold in cimetidine treated groups. The activities of SOD and GSH-Px in the cimetidine groups were increased significantly, and the content of MDA in the cimetidine groups was decreased significantly.

CONCLUSIONS

The results suggested that cimetidine alleviated damage induced by long-term, low-dose-rate neutron and γ combined irradiation via antioxidation and immunomodulation. Cimetidine might be useful as a potent radioprotector for radiotherapy patients as well as for occupational exposure workers.

Acid suppression therapy and allergic reactions

The development of pharmaceutical agents such as sucralfate, histamine 2 (H2) receptor blockers and proton pump inhibitors (PPIs) reducing gastric acidity has been a mile stone for treatment of dyspeptic disorders. However, due to current prescription habits resulting in overuse of these potent drugs as well as over-the-counter (OTC) availability associated with self-medication, substantial health concern is related to the mechanisms of drug action as well as known side effects influencing gastrointestinal physiology. More than a decade ago the first study appeared reporting an association between anti-ulcer drug intake and food allergy development. Ever since this first report several experimental as well as human studies verified this correlation, demonstrating that acid suppressive drugs not only influence the sensitization capacity of orally ingested proteins, but also represent a risk factor for food allergy patients. Additionally, gastric acid suppression was reported to increase the risk for development of drug hypersensitivity reactions. These consequences of anti-ulcer drug intake might on the one hand be associated with direct influence of these drugs on immune responses. On the other hand reduction of gastric acidity leads to impaired gastrointestinal protein degradation. Nevertheless, also disruption of the gastrointestinal barrier function, changes in microbiome or lack of tolerogenic peptic digests might contribute to the connection between anti-ulcer drug intake and allergic reaction. Therefore, these drugs should only be prescribed based on a precise gastroenterological diagnosis taking into consideration allergological mechanisms to ensure patients' safety.

Histamine and gut mucosal immune regulation

Histamine is a biogenic amine with extensive effects on many cell types, mediated by the activation of its four receptors (H1R-H4R). Distinct effects are dependent on receptor subtypes and their differential expression. Within the gastrointestinal tract, histamine is present at relatively high concentrations, particularly during inflammatory responses. In this review, we discuss the immunoregulatory influence of histamine on a number of gastrointestinal disorders, including food allergy, scombroid food poisoning, histamine intolerance, irritable bowel syndrome, and inflammatory bowel disease. It is clear that the effects of histamine on mucosal immune homeostasis are dependent on expression and activity of the four currently known histamine receptors; however, the relative protective or pathogenic effects of histamine on inflammatory processes within the gut are still poorly defined and require further investigation.

A BALB/c mouse model for assessing the potential allergenicity of proteins: comparison of allergen dose, sensitization frequency, timepoint and sex

The present study was to investigate the possibility of using the BALB/c mouse as an animal model for assessing the potential allergenicity of proteins. Specific IgE and IgG1 against ovalbumin were induced by dosing BALB/c mice via intraperitoneal injection (absence of adjuvant). The effects of various allergen doses (5 mg, 0.5 mg or 0.05 mg OVA), sensitization times (twice or five times), timepoints (day 14 or day 28) and sex (male or female) were studied. IL-4, IFN-γ, OVA-specific IgE and IgG1 were measured by enzyme-linked immunosorbent assay (ELISA). A general finding was that mice treated with 0.05 mg OVA had the highest OVA-specific IgE and IgG1, statistically significant higher specific IgE and IgG1 were observed in groups sensitized five times than twice, OVA-specific IgE and IgG1 on day 28 were statistically higher than day 14, and higher IL-4 was observed in OVA-allergic mice than control mice. These results demonstrate that the BALB/c mouse model treated with 0.05 mg OVA intraperitoneally on days 0, 3, 6, 9, 12 might be used for further experiments. OVA-specific IgE and IgG1 should be detected on day 28. Further studies including reproducibility and other conditions were required before using the BALB/c mouse model for assessing the potential allergenicity of proteins.