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BackgroundSphingosine-1-phosphate lyase insufficiency syndrome (SPLIS) is a recently recognized inborn error of metabolism associated with steroid-resistant nephrotic syndrome as well as adrenal insufficiency and immunological, neurological, and skin manifestations. SPLIS is caused by inactivating mutations in SGPL1, encoding the pyridoxal 5'phosphate-dependent enzyme sphingosine-1-phosphate lyase, which catalyzes the final step of sphingolipid metabolism. Some SPLIS patients have undergone kidney transplantation, and others have been treated with vitamin B6 supplementation. In addition, targeted therapies including gene therapy are in preclinical development. In anticipation of clinical trials, it will be essential to characterize the full spectrum and natural history of SPLIS. We performed a retrospective analysis of 76 patients in whom the diagnosis of SPLIS was established in a proband with at least one suggestive finding and biallelic SGPL1 variants identified by molecular genetic testing. The main objective of the study was to identify factors influencing survival in SPLIS subjects.ResultsOverall survival at last report was 50%. Major influences on survival included: (1) age and organ involvement at first presentation; (2) receiving a kidney transplant, and (3) SGPL1 genotype. Among 48 SPLIS patients with nephropathy who had not received a kidney transplant, two clinical subgroups were distinguished. Of children diagnosed with SPLIS nephropathy before age one (n = 30), less than 30% were alive 2 years after diagnosis, and 17% were living at last report. Among those diagnosed at or after age one (n = 18), ~ 70% were alive 2 years after diagnosis, and 72% were living at time of last report. SPLIS patients homozygous for the SPL R222Q variant survived longer compared to patients with other genotypes. Kidney transplantation significantly extended survival outcomes.ConclusionOur results demonstrate that SPLIS is a phenotypically heterogeneous condition. We find that patients diagnosed with SPLIS nephropathy in the first year of life and patients presenting with prenatal findings represent two high-risk subgroups, whereas patients harboring the R222Q SGPL1 variant fare better than the rest. Time to progression from onset of proteinuria to end stage kidney disease varies from less than one month to five years, and kidney transplantation may be lifesaving.

Abstract Background Sphingosine-1-phosphate lyase insufficiency syndrome (SPLIS) is a recently recognized inborn error of metabolism associated with steroid-resistant nephrotic syndrome as well as adrenal insufficiency and immunological, neurological, and skin manifestations. SPLIS is caused by inactivating mutations in SGPL1, encoding the pyridoxal 5’phosphate-dependent enzyme sphingosine-1-phosphate lyase, which catalyzes the final step of sphingolipid metabolism. Some SPLIS patients have undergone kidney transplantation, and others have been treated with vitamin B6 supplementation. In addition, targeted therapies including gene therapy are in preclinical development. In anticipation of clinical trials, it will be essential to characterize the full spectrum and natural history of SPLIS. We performed a retrospective analysis of 76 patients in whom the diagnosis of SPLIS was established in a proband with at least one suggestive finding and biallelic SGPL1 variants identified by molecular genetic testing. The main objective of the study was to identify factors influencing survival in SPLIS subjects. Results Overall survival at last report was 50%. Major influences on survival included: (1) age and organ involvement at first presentation; (2) receiving a kidney transplant, and (3) SGPL1 genotype. Among 48 SPLIS patients with nephropathy who had not received a kidney transplant, two clinical subgroups were distinguished. Of children diagnosed with SPLIS nephropathy before age one (n = 30), less than 30% were alive 2 years after diagnosis, and 17% were living at last report. Among those diagnosed at or after age one (n = 18), ~ 70% were alive 2 years after diagnosis, and 72% were living at time of last report. SPLIS patients homozygous for the SPL R222Q variant survived longer compared to patients with other genotypes. Kidney transplantation significantly extended survival outcomes. Conclusion Our results demonstrate that SPLIS is a phenotypically heterogeneous condition. We find that patients diagnosed with SPLIS nephropathy in the first year of life and patients presenting with prenatal findings represent two high-risk subgroups, whereas patients harboring the R222Q SGPL1 variant fare better than the rest. Time to progression from onset of proteinuria to end stage kidney disease varies from less than one month to five years, and kidney transplantation may be lifesaving.

Sphingosine phosphate lyase insufficiency syndrome (SPLIS) is a genetic disease associated with renal, endocrine, neurological, skin and immune defects. SPLIS is caused by inactivating mutations in SGPL1, which encodes sphingosine phosphate lyase (SPL). SPL catalyzes the irreversible degradation of the bioactive sphingolipid sphingosine-1-phosphate (S1P), a key regulator of lymphocyte egress. The SPL reaction represents the only exit point of sphingolipid metabolism, and SPL insufficiency causes widespread sphingolipid derangements that could additionally contribute to immunodeficiency. Herein, we review SPLIS, the sphingolipid metabolic pathway, and various roles sphingolipids play in immunity. We then explore SPLIS-related immunodeficiency by analyzing data available in the published literature supplemented by medical record reviews in ten SPLIS children. We found 93% of evaluable SPLIS patients had documented evidence of immunodeficiency. Many of the remainder of cases were unevaluable due to lack of available immunological data. Most commonly, SPLIS patients exhibited lymphopenia and T cell-specific lymphopenia, consistent with the established role of the S1P/S1P1/SPL axis in lymphocyte egress. However, low B and NK cell counts, hypogammaglobulinemia, and opportunistic infections with bacterial, viral and fungal pathogens were observed. Diminished responses to childhood vaccinations were less frequently observed. Screening blood tests quantifying recent thymic emigrants identified some lymphopenic SPLIS patients in the newborn period. Lymphopenia has been reported to improve after cofactor supplementation in some SPLIS patients, indicating upregulation of SPL activity. A variety of treatments including immunoglobulin replacement, prophylactic antimicrobials and special preparation of blood products prior to transfusion have been employed in SPLIS. The diverse immune consequences in SPLIS patients suggest that aberrant S1P signaling may not fully explain the extent of immunodeficiency. Further study will be required to fully elucidate the complex mechanisms underlying SPLIS immunodeficiency and determine the most effective prophylaxis against infection., Competing Interests: Declaration of competing interest JDS is co-founder of Sphinxion Therapeutics Inc., which is developing gene therapy for individuals with SPLIS. JDS is an author on patent International Application Serial No. PCT/US2021/018613, “Adeno-Associated Viral (Aav)-Mediated SGPL1 Gene Therapy for Treatment of Sphingosine-1-Phosphate Lyase Insufficiency Syndrome (SPLIS)” published on 08/26/2021 and assigned publication number WO 2021/168140. All other authors declare no conflicts of interest., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Objective: Availability of multimodal treatment strategies, including targeted therapies and immunotherapies, have improved the survival of non-small cell lung carcinoma (NSCLC). However, some patients still progress or respond poorly due to inherent resistance, acquired resistance, or lack of druggable driver mutations. Sphingosine-1-phosphate (S1P) and receptor tyrosine kinase-like orphan receptor (ROR1/2) signaling pathways are activated during lung carcinogenesis., Methods: In this study, we have evaluated the crosstalk of S1P and ROR1/2 signaling pathways in lung cancer cells., Results: S1P treatment of lung cancer cells decreases ROR1 and ROR2 transcript levels. While treatment with PF-543, a pharmacological SphK1 inhibitor or genetic knockdown of SPHK1 by shRNA, raises ROR1 and ROR2. Furthermore, simultaneous inhibition of SphK1 along with ROR1 reduced the migration of lung cancer cells., Conclusion: These findings demonstrate the reciprocal regulation of both pathways, suggesting that both pathways have an inverse relation i.e, in the absence of one pathway, another pathway may take charge of the other pathway. Therefore, simultaneously targeting both pathways could serve as a potential therapeutic target for lung cancer treatment.