Liver immunity,autoimmunity,and inborn errors of immunity

The liver is the front line organ of the immune system.The liver contains the largest collection of phagocytic cells in the body that detect both pathogens that enter through the gut and endogenously produced antigens.This is possible by the highly developed differentiation capacity of the liver immune system between self-antigens or non-self-antigens,such as food antigens or pathogens.As an immune active organ,the liver functions as a gatekeeping barrier from the outside world,and it can create a rapid and strong immune response,under unfavorable conditions.However,the liver's assumed immune status is anti-inflammatory or immuno-tolerant.Dynamic interactions between the numerous populations of immune cells in the liver are key for maintaining the delicate balance between immune screening and immune tolerance.The anatomical structure of the liver can facilitate the preparation of lymphocytes,modulate the immune response against hepatotropic pathogens,and contribute to some of its unique immunological properties,particularly its capacity to induce antigen-specific tolerance.Since liver sinusoidal endothelial cell is fenestrated and lacks a basement membrane,circulating lymphocytes can closely contact with antigens,displayed by endothelial cells,Kupffer cells,and dendritic cells while passing through the sinusoids.Loss of immune tolerance,leading to an autoaggressive immune response in the liver,if not controlled,can lead to the induction of autoimmune or autoinflammatory diseases.This review mentions the unique features of liver immunity,and dysregulated immune responses in patients with autoimmune liver diseases who have a close association with inborn errors of immunity have also been the emphases.

Warburg effect mimicking inborn errors of metabolism in childhood hematologic malignancies:A case-based systematic review

BACKGROUND Type B lactic acidosis and hypoglycemia can occur in various pediatric conditions.In young children with a history of fasting preceding these metabolic derangements,inborn errors of metabolism should be primarily considered.However,the Warburg effect,a rare metabolic complication,can also manifest in children with hematologic malignancies.Only a few reports of this condition in children have been published in the literature.AIM To identify the clinical course,treatment strategies,and outcomes of childhood hematologic malignancies with type B lactic acidosis.METHODS We performed a comprehensive search of the PubMed,Scopus,and Cochrane databases without any time restriction but limited to English language articles.The databases were last accessed on July 1st,2023.RESULTS A total of 20 publications were included in the analysis,all of which were case reports or case series.No higher quality evidence was available.Among children with hematologic malignancies and Warburg effect,there were 14 cases of acute lymphoblastic leukemia and 6 cases of non-Hodgkin’s lymphoma including our illustrative case.Lactic acidosis occurred in 55%of newly diagnosed cases and 45%of relapsed cases.The mean age was 10.3±4.5 years,and 80%of cases were male.The mean serum lactate was 16.9±12.6 mmol/L,and 43.8%of the cases had concomitant hypoglycemia.Lactic acidosis initially subsided in 80%of patients receiving chemotherapy compared to 60%in the contrast group.The mortality rate of newly diagnosed cases was 45.5%,while the relapsed cases represented a 100%mortality rate.All 8 patients reported before 2001 died from disease-related complications.However,patients described in reports published between 2003 and 2023 had a 54.5%rate of complete remission.CONCLUSION This complication has historically led to fatal outcome;however,patients who received chemotherapy showed a more favorable response.Therefore,it is crucial to promptly initiate specific treatment in this context.

Cellular and molecular mechanisms breaking immune tolerance in inborn errors of immunity

In addition to susceptibility to infections,conventional primary immunodeficiency disorders(PIDs)and inborn errors of immunity(IEI)can cause immune dysregulation,manifesting as lymphoproliferative and/or autoimmune disease.Autoimmunity can be the prominent phenotype of PIDs and commonly includes cytopenias and rheumatological diseases,such as arthritis,systemic lupus erythematosus(SLE),and Sjogren’s syndrome(SjS).Recent advances in understanding the genetic basis of systemic autoimmune diseases and PIDs suggest an at least partially shared genetic background and therefore common pathogenic mechanisms.Here,we explore the interconnected pathogenic pathways of autoimmunity and primary immunodeficiency,highlighting the mechanisms breaking the different layers of immune tolerance to self-antigens in selected IEI.

Current strategies for the treatment of inborn errors of metabolism

Inborn errors of metabolism（IEMs） are a large group of inherited disorders characterized by disruption of metabolic pathways due to deficient enzymes, cofactors, or transporters. The rapid advances in the understanding of the molecular pathophysiology of many IEMs, have led to significant progress in the development of many new treatments. The institution and continued expansion of newborn screening provide the opportunity for early treatment, leading to reduced morbidity and mortality. This review provides an overview of the diverse therapeutic approaches and recent advances in the treatment of IEMs that focus on the basic principles of reducing substrate accumulation, replacing or enhancing absent or reduced enzyme or cofactor, and supplementing product deficiency. In addition, the challenges and obstacles of current treatment modalities and future treatment perspectives are reviewed and discussed.

Diagnosis and treatment of an inborn error of bile acid synthesis type 4:A case report

BACKGROUND Inborn error of bile acid synthesis type 4 is a peroxisomal disease with impaired bile acid synthesis caused by a-methylacyl-CoA racemase(AMACR)gene mutation.The disease is usually found in children with mild to severe liver disease,cholestasis and poor fat-soluble vitamin absorption.At present,there is no report of inborn errors of bile acid synthesis type 4 in adults with liver disease and poor fat-soluble vitamin absorption.CASE SUMMARY A 71-year-old man was hospitalized in our department for recurrent liver dysfunction.The clinical manifestations were chronic liver disease and yellow skin and sclera.Serum transaminase,bilirubin and bile acid were abnormally increased;and fat-soluble vitamins decreased.Liver cirrhosis and ascites were diagnosed by computed tomography.The patient had poor coagulation function and ascites and did not undergo liver puncture.Genetic testing showed AMACR gene missense mutation.The patient was diagnosed with inborn error of bile acid synthesis type 4.He was treated with ursodeoxycholic acid,liver protection and vitamin supplementation,and jaundice of the skin and sclera was reduced.The indicators of liver function and the quality of life were significantly improved.CONCLUSION When adults have recurrent liver function abnormalities,physicians should be alert to genetic diseases and provide timely treatment.

Druggable monogenic immune defects hidden in diverse medical specialties:Focus on overlap syndromes

In the last two decades two new paradigms changed our way of perceiving primary immunodeficiencies:An increasing number of immune defects are more associated with inflammatory or autoimmune features rather than with infections.Some primary immune defects are due to hyperactive pathways that can be targeted by specific inhibitors,providing innovative precision treatments that can change the natural history of diseases.In this article we review some of these“druggable”inborn errors of immunity and describe how they can be suspected and diagnosed in diverse pediatric and adult medicine specialties.Since the availability of precision treatments can dramatically impact the course of these diseases,preventing the development of organ damage,it is crucial to widen the awareness of these conditions and to provide practical hints for a prompt detection and cure.

Liver transplantation in Crigler-Najjar syndrome type I disease

BACKGROUND: Crigler-Najjar syndrome type I (CNS I) is a very rare autosomal recessive inherited disease that liver transplantation can properly deal with. METHODS: We present one case of an 18-month-old child with CNS I diagnosed by clinical findings and genetic detecting LTx was performed 5 days after kernicterus broke out and neurological symptoms were successfully reversed. RESULT: Magnetic resonance imaging and magnetic resonance spectroscopy showed encouraging results that brain pathology had a trend to return to normal in 1-year follow-up, combined with electroencephalogram and motor development estimate studies. CONCLUSIONS: Liver transplantation can cure CNS I with reversible neurological symptoms to some extent in time Magnetic resonance spectroscopy may be a future option of predicting brain conditions and selecting suitable patients with CNS I for transplantation.

The Study of Carbamoyl Phosphate Synthetase 1 Deficiency Sheds Light on the Mechanism for Switching On/Off the Urea Cycle

Carbamoyl phosphate synthetase i （CPS1） deficiency （CPS1D） is an inborn error of the urea cycle having autosomal （2q34） recessive inheritance that can cause hyperammonemia and neonatal death or mental retardation. We analyzed the effects on CPS1 activity, kinetic parameters and enzyme stability of missense mutations reported in patients with CPS1 deficiency that map in the 20-kDa C-terminal domain of the enzyme. This domain turns on or off the enzyme depending on whether the essential allosteric activator of CPS 1, N-acetyl- L-glutamate （NAG）, is bound or is not bound to it. To carry out the present studies, we exploited a novel system that allows the expression in vitro and the purification of human CPS1, thus permitting site-directed mutagenesis. These studies have clarified disease causation by individual mutations, identifying functionally important residues, and revealing that a number of mutations decrease the affinity of the enzyme for NAG. Patients with NAG affinity-decreasing mutations might benefit from NAG site saturation therapy with N-carbamyl-L- glutamate （a registered drug, the analog of NAG）. Our results, together with additional present and prior site-directed mutagenesis data for other residues mapping in this domain, suggest an NAG-triggered conformational change in the 134-~4 loop of the C-terminal domain of this enzyme. This change might be an early event in the NAG activation process. Molecular dynamics simulations that were restrained according to the observed effects of the mutations are consistent with this hypothesis, providing further backing for this structurally plausible signaling mechanism by which NAG could trigger urea cycle activation via CPS1.