The hygiene hypothesis, first proposed in 1989, suggested that reduced exposure to infections in early life leads to allergic diseases by the defects in the establishment of immune tolerance. Although many studies provided evidence that some exposure conditions, including family size, antibiotics, probiotics, and viral or bacterial infections, are strongly related to the prevalence of allergic diseases, thereby supporting the hygiene hypothesis, some evidence does not provide acceptable results for the hygiene hypothesis. Further, most studies have focused on patients with asthma or atopic dermatitis, not allergic rhinitis. In this review, we summarize the recent studies for and against the ‘hygiene hypothesis’ and identify causal association with the prevalence of allergic rhinitis.

Allergic rhinitis (AR) is a type of rhinitis accompanied by sensitization to allergens. One of the most clinically important allergens is pollen. Recently, due to climate change and CO 2 air pollution, the flowering period starts earlier and persists longer. In addition, antigenicity due to environmental pollution is also being strengthened. As a result, the sensitization rate to pollen antigens is on the rise. It is known that the prevalence of AR especially caused by pollen is rapidly escalating. Although the causal relationship between pollen exposure and the severity of rhinitis is not precisely established, an association of rhinitis symptoms with the time of pollen scattering exists. In addition, the mixed effect of environmental pollution and pollen may play a role in the development of rhinitis symptoms. Therefore, in order to avoid pollen, it is necessary to constantly improve pollen forecast and minimize the contact with pollen indoors and outdoors. Treatment of AR should be performed according to guidelines. Also, continuous efforts to solve the environmental problems affecting the ecology of pollen are needed.

Among allergic diseases of the Korean pediatric population, allergic rhinitis shows the most rapidly increasing prevalence. Its economic burden is substantial in many Asian countries including South Korea. This investigation of its risk factors aims to reduce the socioeconomic burden by blocking exposure of susceptible individuals to identified causes. However, the risk factors of allergic rhinitis varied considerably depending on the seasons, geographical locations, and populations involved. This review article primarily deals with studies on the risk factors for allergic rhinitis in Korean children that were published during the last 10 years and additionally investigates associated large scale international studies. Our investigation identified several single-nucleotide polymorphisms, inhalant allergens, pollution, tobacco smoke, chemicals, and family affluence as risk factors for allergic rhinitis. In contrast, breastfeeding, older sibling, and microbial diversity were protective factors against allergic rhinitis. This suggests that various genetic and environmental factors might affect the manifestation and presentation of allergic rhinitis complexly. These findings are beneficial as they can provide insights into modifiable risk factors that may hinder the development of allergic rhinitis.

The global worsening of air pollution has decreased the quality of life. Air pollutants can induce oxidative stress, epigenetic changes, and alterations to microRNA expression in the airway and skin, leading to immune dysregulation. Previous epidemiological studies suggest a strong association between outdoor environmental pollution and childhood allergic disease, especially allergic rhinitis (AR). Moreover, traffic-related air pollution has increased the severity and incidence of AR, and heavy traffic has been associated with an increased prevalence of AR. Thus, this review aimed to define outdoor environmental pollution and clarify the mechanisms by which air pollutants aggravate AR. In addition, we performed a systematic review and meta-analysis to summarize the findings of several domestic and international epidemiological and clinical studies about the effects of air pollution on AR in children.

The prevalence of allergic rhinitis in children and adolescents is constantly increasing. However, few studies exist on the relationship between smoking and allergic rhinitis. In addition to conventional cigarettes, electronic and heated cigarettes have recently been introduced, which have several harmful effects. It is hypothesized that smoking and rhinitis are correlated; however, this relationship is complex. Previous studies reported that exposure to smoking during pregnancy is associated with allergic rhinitis development.Unlike the varied results reported in adults, studies on children and adolescents have often correlated direct/indirect smoke with allergic rhinitis, with prolonged exposure being associated with a higher risk of allergic rhinitis, particularly when exposed at an early age. Nonallergic inflammatory reactions and immunoglobulin E-mediated allergic sensitization are assumed to be the underlying mechanisms for the association between allergic rhinitis and smoking. Measures to reduce smoking are warranted to lower the incidence of allergic rhinitis in children and adolescents and to improve their health.

Background: and Purpose: Blood pressure (BP) control is strongly recommended, but BP control rate has not been well studied in patients with stroke. We evaluated the BP control rate with fimasartan-based antihypertensive therapy initiated in patients with recent cerebral ischemia. Methods: This multicenter, prospective, single-arm trial involved 27 centers in South Korea. Key inclusion criteria were recent cerebral ischemia within 90 days and high BP [systolic blood pressure (SBP) >140 mm Hg or diastolic blood pressure (DBP) >90 mm Hg]. BP lowering was initiated with fimasartan. BP management during the follow-up was at the discretion of the responsible investigators. The primary endpoint was the target BP goal achievement rate (<140/90 mm Hg) at 24 weeks. Key secondary endpoints included achieved BP and BP changes at each visit, and clinical events (ClinicalTrials.gov Identifier: NCT03231293). Results: Of 1,035 patients enrolled, 1,026 were included in the safety analysis, and 951 in the efficacy analysis. Their mean age was 64.1 years, 33% were female, the median time interval from onset to enrollment was 10 days, and the baseline SBP and DBP were 162.3±16.0 and 92.2±12.4 mm Hg (mean±SD). During the study period, 55.5% of patients were maintained on fimasartan monotherapy, and 44.5% received antihypertensive therapies other than fimasartan monotherapy at at least one visit. The target BP goal achievement rate at 24-week was 67.3% (48.6% at 4-week and 61.4% at 12-week). The mean BP was 139.0/81.8±18.3/11.7, 133.8/79.2±16.4/11.0, and 132.8/78.5±15.6/10.9 mm Hg at 4-, 12-, and 24-week. The treatment-emergent adverse event rate was 5.4%, including one serious adverse event. Conclusions Fimasartan-based BP lowering achieved the target BP in two-thirds of patients at 24 weeks, and was generally well tolerated.

Allergic rhinitis (AR) is one of the most common allergic diseases characterized by stuffy nose, rhinorrhea, sneezing, and itching. Researchers have indicated an increase in the prevalence of AR and younger-age onset during the last few decades. The increasing burden of AR has caused many researchers to investigate time trends of the prevalence of AR and to identify its risk factors. The most commonly used epidemiological studies are cross-sectional ones such as the International Study of Asthma and Allergies in Childhood study and big data from National Health Insurance Service or National Health and Nutrition Examination Survey. However, these studies have many limitations including recall bias, selection bias, and deficit of objective evaluation. Furthermore, crosssectional studies cannot reflect new risk factors associated with the development of AR. New epidemiological studies will be needed to cover genetic factors, environmental changes, microbiomes, and lifestyles that are known to be risk factors for AR. Further studies will be needed to determine the prevalence, natural history, and risk factors of AR in order to advance our understanding of the pathophysiology, prevention, and management of comorbidities of AR.

Background: and Purpose: Blood pressure (BP) control is strongly recommended, but BP control rate has not been well studied in patients with stroke. We evaluated the BP control rate with fimasartan-based antihypertensive therapy initiated in patients with recent cerebral ischemia. Methods: This multicenter, prospective, single-arm trial involved 27 centers in South Korea. Key inclusion criteria were recent cerebral ischemia within 90 days and high BP [systolic blood pressure (SBP) >140 mm Hg or diastolic blood pressure (DBP) >90 mm Hg]. BP lowering was initiated with fimasartan. BP management during the follow-up was at the discretion of the responsible investigators. The primary endpoint was the target BP goal achievement rate (<140/90 mm Hg) at 24 weeks. Key secondary endpoints included achieved BP and BP changes at each visit, and clinical events (ClinicalTrials.gov Identifier: NCT03231293). Results: Of 1,035 patients enrolled, 1,026 were included in the safety analysis, and 951 in the efficacy analysis. Their mean age was 64.1 years, 33% were female, the median time interval from onset to enrollment was 10 days, and the baseline SBP and DBP were 162.3±16.0 and 92.2±12.4 mm Hg (mean±SD). During the study period, 55.5% of patients were maintained on fimasartan monotherapy, and 44.5% received antihypertensive therapies other than fimasartan monotherapy at at least one visit. The target BP goal achievement rate at 24-week was 67.3% (48.6% at 4-week and 61.4% at 12-week). The mean BP was 139.0/81.8±18.3/11.7, 133.8/79.2±16.4/11.0, and 132.8/78.5±15.6/10.9 mm Hg at 4-, 12-, and 24-week. The treatment-emergent adverse event rate was 5.4%, including one serious adverse event. Conclusions Fimasartan-based BP lowering achieved the target BP in two-thirds of patients at 24 weeks, and was generally well tolerated.

Purpose: Chronic rhinosinusitis with nasal polyps (CRSwNP) is a complex inflammatory disease of the nasal and paranasal sinus mucosa. The disease is associated with mitochondrial dysfunction, structural changes in the mitochondria, and reactive oxygen species (ROS) generation. This study investigated whether there are functional and morphological changes in the mitochondria in the epithelial cells of nasal polyps (NPs) and Staphylococcus aureus enterotoxin B (SEB)-stimulated nasal epithelial cells. Methods: In all, 30 patients with CRSwNP and 15 healthy subjects were enrolled. Mitochondrial ROS (mtROS) and changes in mitochondrial functions and structures were investigated in the uncinate tissue (UT) of healthy controls, the UT or NPs of CRSwNP patients, and human nasal epithelial cells with or without SEB stimulation. Results: Oxidative phosphorylation complexes showed various responses following SEB stimulation in the nasal epithelial cells, and their expressions were significantly higher in the NPs of patients with CRSwNP than in the UT of controls. Generation of mtROS was increased following SEB exposure in nasal epithelial cells and was reduced by pretreatment with MitoTEMPO, which is used as an mtROS scavenger. In the tissues, mtROS was significantly increased in the NPs of CRSwNP patients compared to the UT of controls or CRSwNP patients. The expressions of fusion- and fission-related molecules were also significantly higher in SEB-exposed nasal epithelial cells than in non-exposed cells. In tissues, the expression of fission (fission mediator protein 1)- and fusion (membrane and mitofusin-1, and optic atrophy protein 1)-related molecules was significantly higher in the NPs of CRSwNP patients than in UT of controls or CRSwNP patients. Transmission electron microscopy revealed elongated mitochondria in SEB-exposed nasal epithelial cells and epithelial cells of NPs. Conclusions Production of mtROS, disrupted mitochondrial function, and structural changes in nasal epithelial cells might be involved in the pathogenesis of CRSwNP.