Children with lysinuric protein intolerance: Experience from a lower middle income country

Whole lung lavage and GM-CSF use for pulmonary alveolar proteinosis in an infant with lysinuric protein intolerance: a case report

BACKGROUND

Lysinuric protein intolerance (LPI) is a multi-organ metabolic disorder characterized by the imbalance in absorption and excretion of cationic amino acids like lysine, ornithine and arginine. Infants with LPI typically present with recurrent vomiting, poor growth, interstitial lung disease or renal impairment. The early onset of pulmonary alveolar proteinosis (PAP) has been reported to be associated with a severe form of LPI. Treatment of PAP most commonly consists of whole-lung lavage (WLL) and in autoimmune PAP, granulocyte-macrophage colony stimulating factor (GM-CSF) administration. Nevertheless, GM-CSF therapy in LPI-associated PAP has not been scientifically justified.

CASE PRESENTATION

We describe the case of an 8-month-old infant presenting with respiratory failure due to LPI associated with PAP, who was twice treated with WLL; firstly, while on veno-venous ECMO assistance and then by the use of a selective bronchial blocker. After the two treatments with WLL, she was weaned from daytime respiratory support while on initially subcutaneous, then on inhaled GM-CSF therapy.

CONCLUSIONS

This case supports the notion that GM-CSF therapy might be of benefit in patients with LPI-associated PAP. Further studies are needed to clarify the exact mechanism of GM-CSF in patients with LPI-associated PAP.

Shuttle between arginine and lysine: influence on cancer immunonutrition

Amino acids which are essential nutrients for all cell types' survival are also recognised to serve as opportunistic/alternative fuels in cancers auxotrophic for specific amino acids. Accordingly, restriction of amino acids has been utilised as a therapeutic strategy in these cancers. Contrastingly, amino acid deficiencies in cancer are found to greatly impair immune functions, increasing mortality and morbidity rates. Dietary and supplemental amino acids in such conditions have revealed their importance as 'immunonutrients' by modulating cellular homeostasis processes and halting malignant progression. L-arginine specifically has attracted interest as an immunonutrient by acting as a nodal regulator of immune responses linked to carcinogenesis processes through its versatile signalling molecule, nitric oxide (NO). The quantum of NO generated directly influences the cytotoxic and cytostatic processes of cell cycle arrest, apoptosis, and senescence. However, L-lysine, a CAT transporter competitor for arginine effectively limits arginine input at high L-lysine concentrations by limiting arginine-mediated effects. The phenomenon of arginine-lysine antagonism can, therefore, be hypothesised to influence the immunonutritional effects exerted by arginine. The review highlights aspects of lysine's interference with arginine-mediated NO generation and its consequences on immunonutritional and anti-cancer effects, and discusses possible alternatives to manage the condition. However, further research that considers monitoring lysine levels in arginine immunonutritional therapy is essential to conclude the hypothesis.

Neurological and endocrinological involvement in neonatal lupus erythematosus: a retrospective study at a tertiary hospital in Eastern China

INTRODUCTION

Neonatal lupus erythematosus (NLE) is a rare autoimmune disease that causes transient impairment of multi-organ functions and is mainly caused by maternally transmitted antibodies.

OBJECTIVE

This study aims to investigate the clinical features of infants with NLE, focusing on the presence of neurological and endocrinological involvement.

METHODS

The clinical data of infants diagnosed with NLE at the Children's Hospital of Soochow University from 2011 to 2022 were collected and retrospectively analyzed.

RESULT

In all, 39 patients with NLE were included, and the most common symptom was rash, followed by hematological, hepatic, cardiac, gastrointestinal, neurological, and endocrine symptoms. Among the 10 patients with neurological impairment, intracranial hemorrhage was the most common, followed by convulsions, hydrocephalus, extracerebral space enlargement, and aseptic meningitis. All patients with neurological impairment were positive for anti-SSA/Ro antibodies. Five of these patients were double positive for anti-SSA/Ro and anti-SSB/La antibodies. All 10 patients had multi-organ system involvement, with hematological involvement being the most common, and three patients had varying degrees of developmental delay at the post-discharge follow-up. Nine patients with endocrine impairment were positive for anti-SSA/Ro antibodies, with pancreatic impairment being the most common. There were four cases of hyperinsulinemia and hypoglycemia, one case of diabetes mellitus with ketoacidosis, two cases of hypothyroidism, one case of hypoadrenocorticism, and one case of lysinuric protein intolerance, all of which were normalized before discharge. All patients with endocrine impairment showed hematological involvement, and some showed feeding intolerance as their first symptom. One patient had abnormal liver function at post-discharge follow-up, and two patients had a rash caused by a severe allergy to milk protein.

CONCLUSIONS

At our hospital, no significant gender differences were observed in the occurrence of NLE, and a predominance of skin, blood, liver, and heart involvement was observed. Patients with multiple central nervous system injuries and organ involvement are more likely to have growth retardation. Endocrine disorders are transient in NLE patients, and some showed feeding intolerance as the first manifestation. Key Points •A retrospective investigation of the clinical characteristics and prognosis of 39 NLE patients was performed, focusing on the clinical features of patients with neurological and endocrine system involvement to improve clinicians' understanding of this disease.

Delayed skeletal development and IGF-1 deficiency in a mouse model of lysinuric protein intolerance

SLC7A7 deficiency, or lysinuric protein intolerance (LPI), causes loss of function of the y+LAT1 transporter critical for efflux of arginine, lysine and ornithine in certain cells. LPI is characterized by urea cycle dysfunction, renal disease, immune dysregulation, growth failure, delayed bone age and osteoporosis. We previously reported that Slc7a7 knockout mice (C57BL/6×129/SvEv F2) recapitulate LPI phenotypes, including growth failure. Our main objective in this study was to characterize the skeletal phenotype in these mice. Compared to wild-type littermates, juvenile Slc7a7 knockout mice demonstrated 70% lower body weights, 87% lower plasma IGF-1 concentrations and delayed skeletal development. Because poor survival prevents evaluation of mature knockout mice, we generated a conditional Slc7a7 deletion in mature osteoblasts or mesenchymal cells of the osteo-chondroprogenitor lineage, but no differences in bone architecture were observed. Overall, global Slc7a7 deficiency caused growth failure with low plasma IGF-1 concentrations and delayed skeletal development, but Slc7a7 deficiency in the osteoblastic lineage was not a major contributor to these phenotypes. Future studies utilizing additional tissue-specific Slc7a7 knockout models may help dissect cell-autonomous and non-cell-autonomous mechanisms underlying phenotypes in LPI.