Allergen immunotherapy (AIT) has been used for over a century and has been demonstrated to be effective in treating patients with various allergic diseases. AIT allergens can be administered through various routes, including subcutaneous, sublingual, intralymphatic, oral, or epicutaneous routes. Sublingual immunotherapy (SLIT) has recently gained clinical interest, and it is considered an alternative treatment for allergic rhinitis (AR) and asthma. This review provides an overview of the current evidence-based studies that address the use of SLIT for treating AR, including (1) mechanisms of action, (2) appropriate patient selection for SLIT, (3) the current available SLIT products in Korea, and (4) updated information on its efficacy and safety. Finally, this guideline aims to provide the clinician with practical considerations for SLIT.

Allergen immunotherapy (AIT) is a causative treatment of allergic diseases in which allergen extracts are regularly administered in a gradually escalated doses, leading to immune tolerance and consequent alleviation of allergic diseases. The need for uniform practice guidelines in AIT is continuously growing as the number of potential candidates for AIT increases and new therapeutic approaches are tried. This updated version of the Korean Academy of Asthma Allergy and Clinical Immunology recommendations for AIT, published in 2010, proposes an expert opinion by specialists in allergy, pediatrics, and otorhinolaryngology. This guideline deals with the basic knowledge of AIT, including mechanisms, clinical efficacy, allergen standardization, important allergens in Korea, and special consideration in pediatrics. The article also covers the methodological aspects of AIT, including patient selection, allergen selection, schedule and doses, follow-up care, efficacy measurements, and management of adverse reactions. Although this guideline suggests the optimal dosing schedule, an individualized approach and modifications are recommended considering the situation for each patient and clinic.

As the aging population increases, the number of patients with osteoporosis is gradually rising. Osteoporosis is a metabolic bone disease characterized by low bone mass and the microarchitectural deterioration of bone tissue, resulting in reduced bone strength and an increased risk of low-energy or fragility fractures. Thus, the use of anti-resorptive agents, such as bisphosphonates (BPs), to prevent osteoporotic fractures is growing annually. BPs are effective in reducing hip and other fractures. However, the longer a patient takes BPs, the higher the risk of an atypical femoral fracture (AFF). The exact mechanism by which long-term BP use affects the development of AFFs has not yet been clarified. However, several theories have been suggested to explain the pathogenesis of AFFs, such as suppressed bone remodeling, impaired bone healing, altered bone quality, and femoral morphology. The management of AFFs requires both medical and surgical approaches. BPs therapy should be discontinued immediately, and calcium and vitamin D levels should be evaluated and supplemented if insufficient. Teriparatide can be used for AFFs. Intramedullary nailing is the primary treatment for complete AFFs, and prophylactic femoral nailing is recommended if signs of an impending fracture are detected.

Phospholipase D (PLD) proteins are major enzymes that regulate various cellular functions, such as cell growth, cell migration, membrane trafficking, and cytoskeletal dynamics. As they are responsible for such important biological functions, PLD proteins have been considered promising therapeutic targets for various diseases, including cancer and vascular and neurological diseases. Intriguingly, emerging evidence indicates that PLD1 and PLD2, 2 major mammalian PLD isoenzymes, are the key regulators of bone remodeling; this suggests that these isozymes could be used as potential therapeutic targets for bone diseases, such as osteoporosis and rheumatoid arthritis. PLD1 or PLD2 deficiency in mice can lead to decreased bone mass and dysregulated bone homeostasis. Although both mutant mice exhibit similar skeletal phenotypes, PLD1 and PLD2 play distinct and nonredundant roles in bone cell function. This review summarizes the physiological roles of PLD1 and PLD2 in bone metabolism, focusing on recent findings of the biological functions and action mechanisms of PLD1 and PLD2 in bone cells.