Identification of the low affinity receptor for immunoglobulin E on mouse mast cells and macrophages as Fc gamma RII and Fc gamma RIII

In addition to their well characterized high affinity immunoglobulin E (IgE) receptors (Fc epsilon RI) mast cells have long been suspected to express undefined Fc receptors capable of binding IgE with low affinity. In this paper, we show that Fc gamma RII and Fc gamma RIII, but not Mac-2, on mouse mast cells and macrophages bind IgE-immune complexes. This binding is efficiently competed by 2.4G2, a monoclonal antibody against the extracellular homologous region of both Fc gamma RII and Fc gamma RIII. Furthermore, IgE-immune complexes bind specifically to Fc gamma RII or Fc gamma RIII transfected into COS-7 cells. The association constants of IgE binding estimated from competition experiments are about 3.1 x 10(5) M-1 for Fc gamma RII, and 4.8 x 10(5) M-1 for Fc gamma RIII. Engagement of Fc gamma RII and Fc gamma RIII with IgE-immune complexes (after blocking access to Fc epsilon RI) or with IgG-immune complexes triggers C57.1 mouse mast cells to release serotonin. This release is inhibited by 2.4G2, and at maximum, reaches 30-40% of the intracellular content, about half of the maximal release (60-80%) obtained after Fc epsilon RI engagement. These data demonstrate that mouse Fc gamma RII and Fc gamma RIII are not isotype specific, and that the binding of IgE-immune complexes to these receptors induces cell activation.

Enhancement of macrophage phagocytosis upon iC3b deposition on apoptotic cells

Apoptotic cells activate homologous complement and are opsonized with iC3b. We assessed the effect of iC3b opsonization upon phagocytosis of apoptotic Jurkat cells by macrophages, which were differentiated from THP-1 cells by treatment with retinoic acid. Macrophage phagocytosis of apoptotic Jurkat cells was enhanced upon incubation of the apoptotic cells with normal human serum. The enhanced macrophage phagocytosis of normal serum-treated apoptotic cells was decreased by anti-human C3 F(ab')2 and anti-CR3 and anti-CR4 mAbs to the level of phagocytosis of those treated with complement-blocked serum. These results suggest that interaction between iC3b on apoptotic cells and complement receptor type 3 (CR3) and/or complement receptor type 4 (CR4) on macrophages could play an important role for the clearance of apoptotic cells by macrophages in vivo.

Nationwide surveillance of circulatory collapse associated with levothyroxine administration in very-low-birthweight infants in Japan

BACKGROUND

Although the administration of levothyroxine sodium (LT4) to premature infants had been considered safe, several cases of late-onset circulatory collapse (LCC) following the administration of LT4 in very-low-birth-weight (VLBW) infants have been reported in Japan since 2008. This study was performed to investigate the incidence of LCC associated with the administration of LT4 to VLBW infants.

METHODS

A questionnaire regarding LCC with or without an association with LT4 administration in VLBW infants from 2006 to 2008, was sent to 212 hospitals belonging to the Japan Neonatologist Association.

RESULTS

Data of 8727 VLBW infants were analyzed, and 46 cases of LCC associated with the administration of LT4 were reported in this surveillance. Especially, an analysis for infants weighing between 1000 and 1499 g at birth revealed that the incidence of LCC with the administration of LT4 was higher than that of those without LT4.

CONCLUSIONS

LT4 is widely used for infants, including VLBW infants, and no major complications have been reported. However, our study revealed that more than a few cases of LCC were associated with the administration of LT4 in VLBW infants. In conclusion, careful attention is necessary when initiating the administration of LT4 to VLBW infants.

Binding of phycoerythrin and its conjugates to murine low affinity receptors for immunoglobulin G

Conjugates of R-phycoerythrin are widely used for immunohistochemistry, especially for two-color flow cytometry. Their use is however limited by their apparent tendency to bind non-specifically. Using cells transfected with cDNAs for the murine low affinity receptors for immunoglobulin G (Fc gamma RII and -III) and cells naturally expressing these receptors, we demonstrate that R-phycoerythrin and its conjugates bind specifically and inhibitably to Fc gamma RII and -III. Immunofluorescence stainings of cells bearing these receptors, such as macrophages, monocytes, neutrophils, mast cells, subsets of T cells, and natural killer cells, may therefore not reflect the binding of antibody to antigen, but rather the binding of R-phycoerythrin to the receptors.

Longitudinal analysis of growth and body composition of Japanese 21-OHD patients in childhood

Substitution therapy of glucocorticoid is a major part of the treatment for 21-OHD (21-hydroxylase deficiency). However, the therapy causes two major adverse effects, impairment of linear growth and obesity, so that collecting precise growth data is essential for optimizing the therapy. We longitudinally evaluated the linear growth and the body composition of Japanese 21-OHD patients during childhood. For the present study, we chose 16 patients (eight of each sex) who were diagnosed during the newborn period, and continuously observed them in our institute until they were at least 15 years old. All patients were treated according to the guidelines from The Japanese Society for Pediatric Endocrinology. The final height standard deviation score (Ht-SDS) of all the patients was -1.18 ± 0.85 SD, and no significant differences were observed between males and females or between the simple virilizing form and the salt wasting form. As previously reported, in spite of nearly normal height at the onset of puberty, the pubertal height gains were severely impaired, resulting in reduced final heights. Body composition of the patients was evaluated with BMI-SDS. Our longitudinal data showed that BMI was increased up to +1.23 SD in males and up to +1.75 SD in females, and that adiposity rebound was precipitated. Our study should alert physicians to the risk of metabolic syndrome and provide a framework for further studies of metabolic syndrome in 21-OHD patients.

Initial high dose hydrocortisone (HDC) treatment for 21-hydroxylase deficiency (21-OHD) does not affect linear growth during the first three years of life

An initial high-dose treatment of glucocorticoid has been proposed to prevent chronic androgen excess, improving the final height prognosis of 21-hydroxylase deficiency (21-OHD) patients. In Japan, it is recommended to use an extremely high-dose of hydrocortisone (HDC) (100-200 mg/m(2)/day) for initial treatment by the Japanese Society for Pediatric Endocrinology. However, a precise evaluation of the treatment has not been carried out. In this study, we retrospectively analysed the effects of initial high-dose HDC therapy on the linear growth of classical 21-OHD patients discovered by newborn screening. Thirty patients (14 females) were eligible for this study, all of whom were initiated with high dose HDC therapy. The height standard deviation score (Ht-SDS) was 0.76 ± 0.65 at birth, and decreased to -1SD or less until the age of 12 months, subsequently catching up by 3 years of age (-0.56 ± 0.76). The growth pattern and the height at the age of two years were very similar to those previously observed in patients without initial high dose HDC therapy. We did not find any significant difference in growth retrospectively between the high- or low-dose HDC group (initial treatments of ≥150 mg/m(2)/day and 100 mg/m(2)/day, respectively). Bone ages did not exceed chronological ages at the ages of three and six years. Our data suggest that an initial high-dose HDC treatment does not profoundly affect linear growth during first three years of life and that the treatment could be a valuable option for 21-OHD patients without having an obvious adverse effect on linear growth.

Renal morphology and function from childhood to adulthood in Turner syndrome

BACKGROUND

Turner syndrome (TS) is a chromosomal disorder with various complications, including congenital anomaly of the kidney and urinary tract (CAKUT). However, its renal function remains poorly known. Therefore, this study aimed to evaluate renal function in TS of various ages from childhood to adulthood.

METHODS

We retrospectively analyzed 63 patients with TS who visited our hospital between 1989 and 2020, examined their renal morphology, and analyzed renal function by calculating the estimated glomerular filtration rate (eGFR) using formulas applicable for Japanese populations.

RESULTS

Renal morphological abnormality was observed in 22 cases (35.0%) (horseshoe kidney, 7 [11.1%]; hydronephrosis, 11 [17.5%]; duplex collecting system, 3 [4.8%]; and single unilateral kidney, 1 [1.6%]). We evaluated the eGFR of 47 subjects aged 2.8-39.3 years and classified them into Group 1 (with CAKUT, n = 15) and Group 2 (without CAKUT, n = 32). The eGFR at the first visit and the final follow-up was not statistically different between these groups. In Group 1 with CAKUT, the eGFR was not significantly different between that at the first visit and that at the final follow-up (p = 0.21). During the observation period (median, 7.9 years), the eGFR of all individuals in both groups gradually decreased with age, but did not fall < 60 mL/min/1.73 m², which defines chronic kidney disease (CKD).

CONCLUSIONS

The renal function of TS remained normal in all cases during our investigation period, and no one developed CKD by the age of 40 years.

Lifelong cardiovascular care in Turner syndrome: two cases with review of literature

Cardiovascular disease is one of the most important complications in girls and women with Turner syndrome (TS). Although the latest international guideline provides useful suggestions for the management of cardiovascular diseases in TS, some unknown cardiac conditions warrant physicians' attention and awareness. Here, we have reported two adult cases wherein significant cardiovascular diseases were detected during the transition period. The first case patient was diagnosed with aortic crank deformity and left subclavian artery aneurysm at 14 years based on the report of cardiac catheterization, computed tomography angiography, and cardiac magnetic resonance imaging, which had remained undetected by annual evaluations using transthoracic echocardiography (TTE). This case emphasizes the importance of cardiac reevaluation during the transition period. The second case patient was diagnosed with moderate mitral valve regurgitation (MR) due to mitral valve prolapse at 18 years through TTE, although the first evaluation at 7 years by TTE detected slight MR without any clinical concerns. The condition however progressed to severe MR at 28 years, requiring mitral valvuloplasty. MR is the most common valve disease worldwide, which makes it challenging to comprehend whether the condition is a complication. However, the condition requiring surgery at this age is extremely rare, which implies the possibility of early progression. Because almost all literature on cardiovascular complications in TS is cross-sectional, further information about longitudinal cardiovascular conditions is vital for optimal care for girls and women with TS. The two cases reported in this article provide significant information for improving lifelong cardiovascular health issues in TS.

Optimizing Propranolol Therapy for Infantile Hemangiomas: The Role of the Multidisciplinary Team

BACKGROUND

Oral propranolol therapy is currently the first choice for infants with infantile hemangiomas (IHs) requiring systemic treatment. This study aims to evaluate the safety and effectiveness of oral propranolol therapy for IHs and to assess the role of a multidisciplinary medical team in supporting optimal treatment.

MATERIALS AND METHODS

Clinical data were retrospectively reviewed from medical records in 150 Japanese infants with IH treated with propranolol orally at Toranomon Hospital. Patients with problematic IH, such as tumor-type IH or IH with ulceration, were eligible for inclusion. Treatment was managed by a medical team consisting of pediatricians, dermatologists, pediatric nurses, pharmacists, and nutritionists. Patients' general conditions and vital signs, such as blood pressure, pulse rate, respiratory rate, and blood sugar, were closely monitored before, one hour, and two hours after drug administration.

RESULTS

Close collaboration among multidisciplinary medical team members allowed for accurate patient evaluation, contributing to the early detection of side effects, even if asymptomatic. When side effects were suspected, pediatricians and dermatologists discussed the need to reduce or discontinue the medication. Of the 150 patients, no one experienced severe side effects. Although five cases (3.3%) were suspected of having mild side effects (i.e., hypotension, n = 3; hypotension and hypoglycemia, n = 1; inspiratory stridor, n = 1), treatment could be continued by adjusting the dosage. One hundred twenty patients have completed the oral propranolol therapy with successful outcomes.

CONCLUSIONS

This study provided additional evidence of the safety and effectiveness of oral propranolol therapy in 150 Japanese infants with IH. A well-functioning multidisciplinary medical team is essential for optimal patient treatment.

Clinical Characteristics and Postoperative Growth in Japanese Children with Craniopharyngioma

OBJECTIVE

Craniopharyngioma (CP) has mostly nonspecific symptoms, leading to delayed diagnosis. Early indicators of CP in children are needed for early diagnosis and to detect postoperative growth patterns for their optimal care. This study aimed to investigate the clinical characteristics and postoperative growth patterns in Japanese children with CP.

DESIGN

Retrospective analysis of medical records (2000-2022).

METHODS

Seventy-three children (median age at diagnosis = 9.3 (0.9-18) years; 44 females) from Toranomon Hospital, Tokyo, Japan, who were diagnosed with CP and undergoing trans-sphenoidal or trans-cranial surgery, or both, were followed up for at least 3 years. We assessed clinical characteristics and changes in height and body mass index (BMI) standard deviation scores (SDSs).

RESULTS

The SDSs for height and BMI were -1.7 (-4.0 to 1.3) and 0.21 (-2.3 to 2.2), respectively. Chief complaints at diagnosis were neurologic (n = 25, 34.2%), endocrine (n = 22, 30.1%), or ophthalmic (n = 22, 30.1%), while accompanying neurologic, endocrine, and ophthalmic symptoms were present in 34 (46.6%), 63 (86.3%), and 37 (50.7%) patients, respectively. One year after surgery, growth without growth hormone (GWGH) was detected in seven patients (13%), which could be categorized based on MRI-evident hypothalamic involvement (transient: n = 3, 5.6%; permanent: n = 4, 7.4%). Preoperative hydrocephalus (n = 21, 32.8%) was the only factor significantly associated with postoperative GWGH at 1 year (p = 0.037).

CONCLUSION

Children with CP have distinctive clinical characteristics and postoperative growth patterns. Identifying symptoms using school-based auxological measurements could help in early diagnosis.

Elongation factor-1alpha as a homologous complement activator of Jurkat cells

Although increasing evidence exist suggesting that apoptotic cells activate homologous complement, the homologous complement activators are only poorly characterized. We found that cell lysate of Jurkat cells contained a homologous complement activator of 50 kDa. Digestion of the 50 kDa activator with lysylendopeptidase yielded peptide fragments, with sequences identical to those of EF-1alpha. The 50 kDa activator was removed by immunoadsorption with anti-EF-1alpha, suggesting that the 50 kDa activator is EF-1alpha. The homologous complement activation did not proceed with EGTA-serum. In addition, C4b, a fragment produced by activation of the classical or lectin pathways was found to bind with EF-1alpha. These results suggest that EF-1alpha activates the homologous complement through the classical or lectin pathway.