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Summary: Inborn errors of immunity (IEI) present a unique paradigm in the realm of gene therapy, emphasizing the need for precision in therapeutic design. As gene therapy transitions from broad‐spectrum gene addition to careful modification of specific genes, the enduring safety and effectiveness of these therapies in clinical settings have become crucial. This review discusses the significance of IEIs as foundational models for pioneering and refining precision medicine. We explore the capabilities of gene addition and gene correction platforms in modifying the DNA sequence of primary cells tailored for IEIs. The review uses four specific IEIs to highlight key issues in gene therapy strategies: X‐linked agammaglobulinemia (XLA), X‐linked chronic granulomatous disease (X‐CGD), X‐linked hyper IgM syndrome (XHIGM), and immune dysregulation, polyendocrinopathy, enteropathy, X‐linked (IPEX). We detail the regulatory intricacies and therapeutic innovations for each disorder, incorporating insights from relevant clinical trials. For most IEIs, regulated expression is a vital aspect of the underlying biology, and we discuss the importance of endogenous regulation in developing gene therapy strategies. [ABSTRACT FROM AUTHOR]

Summary: FOXP3 gene is a key transcription factor driving immune tolerance and its deficiency causes immune dysregulation, polyendocrinopathy, enteropathy X‐linked syndrome (IPEX), a prototypic primary immune regulatory disorder (PIRD) with defective regulatory T (Treg) cells. Although life‐threatening, the increased awareness and early diagnosis have contributed to improved control of the disease. IPEX currently comprises a broad spectrum of clinical autoimmune manifestations from severe early onset organ involvement to moderate, recurrent manifestations. This review focuses on the mechanistic advancements that, since the IPEX discovery in early 2000, have informed the role of the human FOXP3+ Treg cells in controlling peripheral tolerance and shaping the overall immune landscape of IPEX patients and carrier mothers, contributing to defining new treatments. [ABSTRACT FROM AUTHOR]

Phage immunoprecipitation sequencing (PhIP-seq) allows for unbiased, proteome-wide autoantibody discovery across a variety of disease settings, with identification of disease-specific autoantigens providing new insight into previously poorly understood forms of immune dysregulation. Despite several successful implementations of PhIP-seq for autoantigen discovery, including our previous work (Vazquez et al., 2020), current protocols are inherently difficult to scale to accommodate large cohorts of cases and importantly, healthy controls. Here, we develop and validate a high throughput extension of PhIP-seq in various etiologies of autoimmune and inflammatory diseases, including APS1, IPEX, RAG1/2 deficiency, Kawasaki disease (KD), multisystem inflammatory syndrome in children (MIS-C), and finally, mild and severe forms of COVID-19. We demonstrate that these scaled datasets enable machine-learning approaches that result in robust prediction of disease status, as well as the ability to detect both known and novel autoantigens, such as prodynorphin (PDYN) in APS1 patients, and intestinally expressed proteins BEST4 and BTNL8 in IPEX patients. Remarkably, BEST4 antibodies were also found in two patients with RAG1/2 deficiency, one of whom had very early onset IBD. Scaled PhIP-seq examination of both MIS-C and KD demonstrated rare, overlapping antigens, including CGNL1, as well as several strongly enriched putative pneumonia-associated antigens in severe COVID-19, including the endosomal protein EEA1. Together, scaled PhIP-seq provides a valuable tool for broadly assessing both rare and common autoantigen overlap between autoimmune diseases of varying origins and etiologies.

The interpretation of clinical diagnostic results in suspected inborn errors of immunity, including Tregopathies, is hampered by the lack of age-stratified reference values for regulatory T cells (Treg) in the pediatric population and a consensus on which Treg immunophenotype to use. Regulatory B cells (Breg) are an important component of the regulatory system that have been poorly studied in the pediatric population. We analyzed (1) the correlation between the three immunophenotypic definitions of Treg (CD4+CD25hiCD127low, CD4+CD25hiCD127lowFoxP3+, CD4+CD25hiFoxP3+), and with CD4+CD25hi and (2) the changes in Treg and Breg frequencies and their maturation status with age. We performed peripheral blood immunophenotyping of Treg and Breg (CD19+CD24hiCD38hi) by flow cytometry in 55 healthy pediatric controls. We observed that Treg numbers varied depending on the definition used, and the frequency ranged between 3.3–9.7% for CD4+CD25hiCD127low, 0.07-1.6% for CD4+CD25hiCD127lowFoxP3+, and 0.24-2.83% for CD4+CD25hiFoxP3+. The correlation between the three definitions of Treg was positive for most age ranges, especially between the two intracellular panels and with CD4+CD25hi vs CD4+CD25hiCD127low. Treg and Breg frequencies tended to decline after 7 and 3 years onwards, respectively. Treg’s maturation status increased with age, with a decline of naïve Treg and an increase in memory/effector Treg from age 7 onwards. Memory Breg increased progressively from age 3 onwards. In conclusion, the number of Treg frequencies spans a wide range depending on the immunophenotypic definition used despite a good level of correlation exists between them. The decline in numbers and maturation process with age occurs earlier in Breg than in Treg. [ABSTRACT FROM AUTHOR]

Immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome is a monogenic disorder caused by mutations in the FOXP3 gene, required for generation of regulatory T (Treg) cells. Loss of Treg cells leads to immune dysregulation characterized by multi-organ autoimmunity and early mortality. Hematopoietic stem cell (HSC) transplantation can be curative, but success is limited by autoimmune complications, donor availability and/or graft-vs.-host disease. Correction of FOXP3 in autologous HSC utilizing a homology-directed repair (HDR)-based platform may provide a safer alternative therapy. Here, we demonstrate efficient editing of FOXP3 utilizing co-delivery of Cas9 ribonucleoprotein complexes and adeno-associated viral vectors to achieve HDR rates of >40% in vitro using mobilized CD34+ cells from multiple donors. Using this approach to deliver either a GFP or a FOXP3 cDNA donor cassette, we demonstrate sustained bone marrow engraftment of approximately 10% of HDR-edited cells in immune-deficient recipient mice at 16 weeks post-transplant. Further, we show targeted integration of FOXP3 cDNA in CD34+ cells from an IPEX patient and expression of the introduced FOXP3 transcript in gene-edited primary T cells from both healthy individuals and IPEX patients. Our combined findings suggest that refinement of this approach is likely to provide future clinical benefit in IPEX.

Immune dysregulation, polyendocrinopathy, enteropathy, X‐linked (IPEX) is characterized by failure to thrive, severe chronic diarrhea, neonatal type 1 diabetes or thyroiditis, and eczematous dermatitis. We report a patient with infantile onset IPEX syndrome who developed vitiligo, alopecia, and chronic diarrhea. Awaiting stem cell transplant, he had multiple episodes of sepsis and succumbed at the age of 10 months. The constellation of symptoms is important to prompt clinicians to suspect this rare syndrome as early hematopoietic stem cell transplantation is the only cure for IPEX patients. [ABSTRACT FROM AUTHOR]

Purpose: FOXP3 deficiency results in severe multisystem autoimmunity in both mice and humans, driven by the absence of functional regulatory T cells. Patients typically present with early and severe autoimmune polyendocrinopathy, dermatitis, and severe inflammation of the gut, leading to villous atrophy and ultimately malabsorption, wasting, and failure to thrive. In the absence of successful treatment, FOXP3-deficient patients usually die within the first 2 years of life. Hematopoietic stem cell transplantation provides a curative option but first requires adequate control over the inflammatory condition. Due to the rarity of the condition, no clinical trials have been conducted, with widely unstandardized therapeutic approaches. We sought to compare the efficacy of lead therapeutic candidates rapamycin, anti-CD4 antibody, and CTLA4-Ig in controlling the physiological and immunological manifestations of Foxp3 deficiency in mice. Method: We generated Foxp3-deficient mice and an appropriate clinical scoring system to enable direct comparison of lead therapeutic candidates rapamycin, nondepleting anti-CD4 antibody, and CTLA4-Ig. Results: We found distinct immunosuppressive profiles induced by each treatment, leading to unique protective combinations over distinct clinical manifestations. CTLA4-Ig provided superior breadth of protective outcomes, including highly efficient protection during the transplantation process. Conclusion: These results highlight the mechanistic diversity of pathogenic pathways initiated by regulatory T cell loss and suggest CTLA4-Ig as a potentially superior therapeutic option for FOXP3-deficient patients. [ABSTRACT FROM AUTHOR]

Regulatory T (Treg) cells maintain immune tolerance through the master transcription factor forkhead box P3 (FOXP3), which is crucial for Treg cell function and homeostasis. We identified an IPEX (immune dysregulation polyendocrinopathy enteropathy X-linked) syndrome patient with a FOXP3 mutation in the domain swap interface of the protein. Recapitulation of this Foxp3 variant in mice led to the development of an autoimmune syndrome consistent with an unrestrained T helper type 2 (Th2) immune response. Genomic analysis of Treg cells by RNA-sequencing, Foxp3 chromatin immunoprecipitation followed by high-throughput DNA sequencing (ChIP-sequencing), and H3K27ac-HiChIP revealed a specific de-repression of the Th2 transcriptional program leading to the generation of Th2-like Treg cells that were unable to suppress extrinsic Th2 cells. Th2-like Treg cells showed increased intra-chromosomal interactions in the Th2 locus, leading to type 2 cytokine production. These findings identify a direct role for Foxp3 in suppressing Th2-like Treg cells and implicate additional pathways that could be targeted to restrain Th2 trans-differentiated Treg cells.

BackgroundImmunodysregulation polyendocrinopathy enteropathy x-linked (IPEX) syndrome is a monogenic autoimmune disease caused by FOXP3 mutations. Because it is a rare disease, the natural history and response to treatments, including allogeneic hematopoietic stem cell transplantation (HSCT) and immunosuppression (IS), have not been thoroughly examined.ObjectiveThis analysis sought to evaluate disease onset, progression, and long-term outcome of the 2 main treatments in long-term IPEX survivors.MethodsClinical histories of 96 patients with a genetically proven IPEX syndrome were collected from 38 institutions worldwide and retrospectively analyzed. To investigate possible factors suitable to predict the outcome, an organ involvement (OI) scoring system was developed.ResultsWe confirm neonatal onset with enteropathy, type 1 diabetes, and eczema. In addition, we found less common manifestations in delayed onset patients or during disease evolution. There is no correlation between the site of mutation and the disease course or outcome, and the same genotype can present with variable phenotypes. HSCT patients (n = 58) had a median follow-up of 2.7 years (range, 1 week-15 years). Patients receiving chronic IS (n = 34) had a median follow-up of 4 years (range, 2 months-25 years). The overall survival after HSCT was 73.2% (95% CI, 59.4-83.0) and after IS was 65.1% (95% CI, 62.8-95.8). The pretreatment OI score was the only significant predictor of overall survival after transplant (P = .035) but not under IS.ConclusionsPatients receiving chronic IS were hampered by disease recurrence or complications, impacting long-term disease-free survival. When performed in patients with a low OI score, HSCT resulted in disease resolution with better quality of life, independent of age, donor source, or conditioning regimen.

Immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome is a rare X-linked recessive immunodeficiency caused by mutations in the forkhead box protein 3 (FOXP3) gene. IPEX is characterized by the onset of intractable diarrhea, type 1 diabetes mellitus (T1DM), and eczema in the early stages of life. The typical clinic triad for IPEX is not always seen. Here, we report a 15-year-old male patient with atypical IPEX syndrome complicated with severe eosinophilic gastritis (EG) and pyloric stenosis. The patient had noticeable eczema during the first year of life and had a history of food allergies. At the age of 3 years, the patient was diagnosed with EG, Helicobacter pylori (HP) infection, pyloric stenosis with recurrent vomiting, and failure to thrive. The patient did not respond to long-term symptomatic treatments in the following years, including methylprednisolone, proton pump inhibitors (PPI), L-glutamine and sodium gualenate granules, anti-HP therapy, and balloon dilation. At the age of 12 years, the patient received surgical interventions, including a laparoscopic jejunostomy feeding tube placement, gastrojejunal anastomosis bypass, and jejunal-jejunal end-to-side anastomosis. Intractable diarrhea and T1DM were not present in the patient. At the age of 14 years, the patient was diagnosed with IPEX syndrome due to a c.748–750del (p.Lys250del) mutation in the leucine zipper domain of the FOXP3 protein. The patient underwent matched sibling peripheral blood hematopoietic stem cell transplantation (HSCT) and showed good evolution after 3 months of HSCT. In summary, this case report provides information of unusual gastrointestinal findings in IPEX syndrome and highlights the need for increased awareness and early diagnosis of IPEX syndrome, which is vital for improving the patient's outcome.

Phage immunoprecipitation sequencing (PhIP-seq) allows for unbiased, proteome-wide autoantibody discovery across a variety of disease settings, with identification of disease-specific autoantigens providing new insight into previously poorly understood forms of immune dysregulation. Despite several successful implementations of PhIP-seq for autoantigen discovery, including our previous work (Vazquez et al., 2020), current protocols are inherently difficult to scale to accommodate large cohorts of cases and importantly, healthy controls. Here, we develop and validate a high throughput extension of PhIP-seq in various etiologies of autoimmune and inflammatory diseases, including APS1, IPEX, RAG1/2 deficiency, Kawasaki disease (KD), multisystem inflammatory syndrome in children (MIS-C), and finally, mild and severe forms of COVID-19. We demonstrate that these scaled datasets enable machine-learning approaches that result in robust prediction of disease status, as well as the ability to detect both known and novel autoantigens, such as prodynorphin (PDYN) in APS1 patients, and intestinally expressed proteins BEST4 and BTNL8 in IPEX patients. Remarkably, BEST4 antibodies were also found in two patients with RAG1/2 deficiency, one of whom had very early onset IBD. Scaled PhIP-seq examination of both MIS-C and KD demonstrated rare, overlapping antigens, including CGNL1, as well as several strongly enriched putative pneumonia-associated antigens in severe COVID-19, including the endosomal protein EEA1. Together, scaled PhIP-seq provides a valuable tool for broadly assessing both rare and common autoantigen overlap between autoimmune diseases of varying origins and etiologies.

Immune dysregulation polyendocrinopathy enteropathy X linked (IPEX) syndrome is an uncurable disease of the immune system, with immune dysregulation that is caused by mutations in FOXP3. Current treatment options, such as pharmacological immune suppression and allogeneic hematopoietic stem cell transplantation, have been beneficial but present limitations, and their life‐long consequences are ill‐defined. Other similar blood monogenic diseases have been successfully treated using gene transfer in autologous patient cells, thus providing an effective and less invasive therapeutic. Development of gene therapy for patients with IPEX is particularly challenging because successful strategies must restore the complex expression profile of the transcription factor FOXP3, ensuring it is tightly regulated and its cell subset‐specific roles are maintained. This review summarizes current efforts toward achieving gene therapy to treat immune dysregulation in IPEX patients. [ABSTRACT FROM AUTHOR]

Introduction: The Forkhead box protein P3 (FOXP3) is a transcription factor central to the function of regulatory T cells (Treg). Mutations in the FOXP3 gene lead to a systemic disease called immune dysregulation, polyendocrinopathy, and enteropathy, an X-linked syndrome (IPEX) characterized by the triad of early-onset intractable diarrhea, type 1 diabetes, and eczema. An atypical presentation of IPEX has been reported. Method: We report rare cases with equivocal clinical associations that included inflammatory, kidney, and hematologic involvements screened with massively parallel sequencing techniques. Results: Two patients with hemizygous mutations of FOXP3 [c.779T>A (p.L260Q)] and [c.1087A>G (p.I363V)] presented clinical manifestations not included in typical cases of IPEX: one was a 16-year-old male patient with an initial clinical diagnosis of autoimmune lymphoproliferative syndrome (ALPS) and who developed proteinuria and decreased kidney function due to membranous nephropathy, an autoimmune renal condition characterized by glomerular sub-epithelial antibodies. The second patient was a 2-year-old child with bone marrow failure who developed the same glomerular lesions of membranous nephropathy and received a bone marrow transplantation. High levels of IgG4 in serum, bone marrow, and kidney led to the definition of IgG4-related kidney disease (IgG4 RKD) in this young boy. The circulating Treg levels were normal in the former case and very low in the second. Conclusion: Two atypical associations of functional mutations of FOXP3 that include ALPS and IgG4 RKD are described. Membranous nephropathy leading to renal failure completed in both cases the clinical phenotypes that should be included in the clinical panorama of FOXP3 failure. [ABSTRACT FROM AUTHOR]

Nowadays, modeling and forecasting electricity spot prices are challenging due to their specific features, including multiple seasonalities, calendar effects, and extreme values (also known as jumps, spikes, or outliers). This study aims to provide a comprehensive analysis of electricity price forecasting by comparing several outlier filtering techniques followed by various modeling frameworks. To this end, extreme values are first treated with five different filtering techniques and are then replaced by four different outlier replacement approaches. Next, the spikes-free series is divided into deterministic and stochastic components. The deterministic component includes long-term trend, yearly and weekly seasonalities, and bank holidays and is estimated through parametric and nonparametric approaches. On the other hand, the stochastic component accounts for the short-run dynamics of the price time series and is modeled using different univariate and multivariate models. The one-day-ahead out-of-sample forecast results for the Italian Power Exchange (IPEX), obtained for a whole year, suggest that the outliers pre-filtering give a high accuracy gain. In addition, multivariate modeling for the stochastic component outperforms univariate models.

Efficient modeling and forecasting of electricity prices are essential in today’s competitive electricity markets. However, price forecasting is not easy due to the specific features of the electricity price series. This study examines the performance of an ensemble-based technique for forecasting short-term electricity spot prices in the Italian electricity market (IPEX). To this end, the price time series is divided into deterministic and stochastic components. The deterministic component that includes long-term trends, annual and weekly seasonality, and bank holidays, is estimated using semi-parametric techniques. On the other hand, the stochastic component considers the short-term dynamics of the price series and is estimated by time series and various machine learning algorithms. Based on three standard accuracy measures, the results indicate that the ensemble-based model outperforms the others, while the random forest and ARMA are highly competitive.

In this article we revised the literature on Inborn Errors of Immunity (IEI) keeping our focus on those diseases presenting with intrauterine or perinatal clinical manifestations. We opted to describe our findings according to the IEI categories established by the International Union of Immunological Societies, predominantly addressing the immunological features of each condition or group of diseases. The main finding is that such precocious manifestations are largely concentrated in the group of primary immune regulatory disorders (PIRDs) and not in the group of classical immunodeficiencies. The IEI categories with higher number of immunological manifestations in utero or in perinatal period are: (i) diseases of immune dysregulation (HLH, IPEX and other Tregopathies, autosomal recessive ALPS with complete lack of FAS protein expression) and (ii) autoinflammatory diseases (NOMID/CINCA, DIRA and some interferonopathies, such as Aicardi-Goutières syndrome, AGS, and USP18 deficiency). Regarding the other IEI categories, some patients with Omenn syndrome (an atypical form of SCID), and a few X-linked CGD patients present with clinical manifestations at birth associated to immune dysregulation. The most frequent clinical features were hydrops fetalis, intrauterine growth retardation leading to fetal loss, stillbirths, and prematurity, as in HLH and IPEX. Additionally, pseudo-TORCH syndrome was observed in AGS and in USP18 deficiency. The main goal of our review was to contribute to increasing the medical awareness of IEI with intrauterine and perinatal onset, which has obvious implications for diagnosis, treatment, and genetic counseling.

IntroductionThe Forkhead box protein P3 (FOXP3) is a transcription factor central to the function of regulatory T cells (Treg). Mutations in the FOXP3 gene lead to a systemic disease called immune dysregulation, polyendocrinopathy, and enteropathy, an X-linked syndrome (IPEX) characterized by the triad of early-onset intractable diarrhea, type 1 diabetes, and eczema. An atypical presentation of IPEX has been reported.MethodWe report rare cases with equivocal clinical associations that included inflammatory, kidney, and hematologic involvements screened with massively parallel sequencing techniques.ResultsTwo patients with hemizygous mutations of FOXP3 [c.779T>A (p.L260Q)] and [c.1087A>G (p.I363V)] presented clinical manifestations not included in typical cases of IPEX: one was a 16-year-old male patient with an initial clinical diagnosis of autoimmune lymphoproliferative syndrome (ALPS) and who developed proteinuria and decreased kidney function due to membranous nephropathy, an autoimmune renal condition characterized by glomerular sub-epithelial antibodies. The second patient was a 2-year-old child with bone marrow failure who developed the same glomerular lesions of membranous nephropathy and received a bone marrow transplantation. High levels of IgG4 in serum, bone marrow, and kidney led to the definition of IgG4-related kidney disease (IgG4 RKD) in this young boy. The circulating Treg levels were normal in the former case and very low in the second.ConclusionTwo atypical associations of functional mutations of FOXP3 that include ALPS and IgG4 RKD are described. Membranous nephropathy leading to renal failure completed in both cases the clinical phenotypes that should be included in the clinical panorama of FOXP3 failure.

Over the last three decades, accurate modeling and forecasting of electricity prices has become a key issue in competitive electricity markets. As electricity price series usually exhibit several complex features, such as high volatility, seasonality, calendar effect, non-stationarity, non-linearity and mean reversion, price forecasting is not a trivial task. However, participants of electricity market need price forecast to make decisions in their daily activity in the market, such as trading, risk management or future planning. In this study we consider linear and nonlinear models for one-day-ahead forecast of electricity prices using components estimation techniques. This approach requires to filter out the structural, deterministic components from the original time series and to model the residual component by means of some stochastic process. The final forecast is obtained by combining the predictions of both these components. In this work, linear and non-linear models are applied to both, deterministic and stochastic, components. In the case of stochastic component, AutoRegressive, Nonparametric AutoRegressive, Functional AutoRegressive, and Nonparametric Functional AutoRegressive have been considered. Furthermore, two naïve benchmarks are applied directly to the price time series and their results are compared with our proposed models. An application of the proposed methodology is presented for the Italian electricity market (IPEX). Our analysis suggests that, in terms of Mean Absolute Error, Mean Absolute Percentage Error, and Pearson correlation coefficient, best results are obtained when deterministic component is estimated by using parametric approach. Further, Functional AutoRegressive model performs relatively better than the rest while Nonparametric AutoRegressive is highly competitive.

ALPS and IPEX are two well-characterized inborn errors of immunity with immune dysregulation, considered as two master models of monogenic auto-immune diseases. Thus, with autoimmunity as their primary clinical manifestation, these two entities may show clinical overlap. Traditionally, immunological biomarkers are used to establish an accurate differential diagnosis. Herein, we describe a patient who presented with clinical features and biomarkers fulfilling the diagnostic criteria of ALPS. Severe apoptotic defect was also shown in the patient’s cell lines and PHA-activated peripheral blood lymphocytes. Sanger sequencing of the FAS gene did not reveal any causal mutation. NGS screening revealed a novel deleterious variant located in the N terminal repressor domain of FOXP3 but no mutations in the FAS pathway-related genes. TEMRA cells (terminally differentiated effector memory cells re-expressing CD45RA) and PD1 expression were increased arguing in favor of T-cell exhaustion, which could be induced by unrestrained activation of T effector cells because of Treg deficiency. Moreover, defective FOXP3 observed in the patient could intrinsically induce increased proliferation and resistance to apoptosis in T effector cells. This observation expands the spectrum of FOXP3 deficiency and underscores the role of NGS in detecting mutations that induce overlapping phenotypes among inborn errors of immunity with immune dysregulation. In addition, these findings suggest a potential link between FOXP3 and FAS pathways.

CD25, Signal transducer and activator of transcription 5B (STAT5B) and Forkhead box P3 (FOXP3) are critical mediators of Interleukin-2 (IL-2) signaling pathway in regulatory T cells (Tregs). CD25 (i.e., IL-2 Receptor α) binds with high affinity to IL-2, activating STAT5B-mediated signaling that eventually results in transcription of FOXP3, a master regulator of Treg function. Consequently, loss-of-function mutations in these proteins give rise to Treg disorders (i.e., Tregopathies) that clinically result in multiorgan autoimmunity. Immunodysregulation, Polyendocrinopathy Enteropathy X-linked (IPEX), due to mutations in FOXP3, has historically been the prototype of Tregopathies. This review describes current knowledge about defects in CD25, STAT5B, and FOXP3, highlighting that these disorders both share a common biological background and display comparable clinical features. However, specific phenotypes are associated with each of these syndromes, while certain laboratory findings could be helpful tools for clinicians, in order to achieve a prompt genetic diagnosis. Current treatment strategies will be outlined, keeping an eye on gene editing, an interesting therapeutic perspective that could definitely change the natural history of these disorders.

ALPS and IPEX are two well-characterized inborn errors of immunity with immune dysregulation, considered as two master models of monogenic auto-immune diseases. Thus, with autoimmunity as their primary clinical manifestation, these two entities may show clinical overlap. Traditionally, immunological biomarkers are used to establish an accurate differential diagnosis. Herein, we describe a patient who presented with clinical features and biomarkers fulfilling the diagnostic criteria of ALPS. Severe apoptotic defect was also shown in the patient's cell lines and PHA-activated peripheral blood lymphocytes. Sanger sequencing of the FAS gene did not reveal any causal mutation. NGS screening revealed a novel deleterious variant located in the N terminal repressor domain of FOXP3 but no mutations in the FAS pathway-related genes. TEMRA cells (terminally differentiated effector memory cells re-expressing CD45RA) and PD1 expression were increased arguing in favor of T-cell exhaustion, which could be induced by unrestrained activation of T effector cells because of Treg deficiency. Moreover, defective FOXP3 observed in the patient could intrinsically induce increased proliferation and resistance to apoptosis in T effector cells. This observation expands the spectrum of FOXP3 deficiency and underscores the role of NGS in detecting mutations that induce overlapping phenotypes among inborn errors of immunity with immune dysregulation. In addition, these findings suggest a potential link between FOXP3 and FAS pathways. [ABSTRACT FROM AUTHOR]

Purpose of Review: We describe the clinical and genetic findings in four patients from a single family who presented with refractory psoriatic arthritis and were hemizygous in the forkhead box protein 3 (FOXP3) gene (c.1222G>A). Recent Findings: We report four siblings with hemizygous mutation in the FOXP3 gene (c.1222G>A) who presented with type 1 diabetes mellitus and psoriatic arthritis poorly responsive to treatment. Our findings expand the phenotype spectrum of FOXP3 mutations. Summary: Immune dysregulation, polyendocrinopathy, and enteropathy, X-linked (IPEX) syndrome is a rare disorder caused by mutations in FOXP3 gene, which lead to early onset of constellation of autoimmune manifestations. This report highlights the influence of immune dysregulation in juvenile arthritis. [ABSTRACT FROM AUTHOR]

Treg deficiency causes a lethal, CD4+ T cell-driven autoimmune disease called IPEX syndrome (immunodysregulation, polyendocrinopathy, and enteropathy, with X-linked inheritance) in humans and in the scurfy (SF) mouse, a mouse model of the disease. Feeding Limosilactobacillus reuteri DSM 17938 (LR 17938, LR) to SF mice reprograms the gut microbiota, reduces disease progression, and prolongs lifespan. However, the efficacy and mechanism of LR, compared with other probiotics, in producing these effects is unknown. We compared LR with Lacticaseibacillus rhamnosus GG (LGG), an extensively investigated probiotic. LR was more effective than LGG in prolonging survival. Both probiotics restored the fecal microbial alpha diversity, but they produced distinct fecal bacterial clusters and differentially modulated microbial relative abundance (RA). LR increased the RA of phylum_Firmicutes, genus_Oscillospira whereas LR reduced phylum_Bacteroidetes, genus_Bacteroides and genus_Parabacteroides, reversing changes attributed to the SF phenotype. LGG primarily reduced the RA of genus_Bacteroides. Both LR and LGG reduced the potentially pathogenic taxon class_cproteobacteria. Plasma metabolomics revealed substantial differences among 696 metabolites. We observed similar changes of many clusters of metabolites in SF mice associated with treatment with either LR or LGG. However, a unique effect of LR was to increase the abundance of plasma adenosine metabolites such as inosine, which we previously showed had immune modulatory effects. In conclusion: 1) different probiotics produce distinct signatures in the fecal microbial community in mice with Treg deficiency; and 2) when comparing different probiotics, there are strain-specific microbial products with different anti-inflammatory properties, reinforcing the concept that “one size does not fit all” in the treatment of autoimmune disease. [ABSTRACT FROM AUTHOR]

Immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome is a rare immune deficiency with a broad clinical presentation. IPEX syndrome causes dysfunctional regulatory T cells, increasing the risk of autoimmune diseases. In this case report, we describe a 7-year-old boy with lymphocytic interstitial pneumonia and bullous pemphigoid who was recently diagnosed with IPEX syndrome. [ABSTRACT FROM AUTHOR]

Immune dysregulation, polyendocrinopathy, and enteropathy, X-linked (IPEX) syndrome is a rare disorder that has become a model of monogenic autoimmunity. IPEX is caused by mutations in FOXP3 gene, a master regulator of regulatory T cells (Treg). Cases reported in the last 20 years demonstrate that IPEX clinical spectrum encompasses more than the classical triad of early-onset intractable diarrhea, type 1 diabetes (T1D) and eczema. Atypical cases of IPEX include patients with late-onset of symptoms, single-organ involvement, mild disease phenotypes or rare clinical features (e.g., atrophic gastritis, interstitial lung disease, nephropathy etc.). Several atypical presentations have recently been reported, suggesting that IPEX incidence might be underestimated. Immunosuppression (IS) treatment strategies can control the disease, however at the moment allogeneic hematopoietic stem cell transplantation (HSCT) is the only available definitive cure, therefore it is important to achieve a prompt diagnosis. This review aims to describe unusual clinical phenotypes, beyond classical IPEX. Overall, our analysis contributes to increase awareness and finally improve diagnosis and treatment intervention in IPEX in order to ensure a good quality of life.

IPEX is one of the few Inborn Errors of Immunity that may manifest in the fetal period, and its intrauterine forms certainly represent the earliest human autoimmune diseases. Here, we review the clinical, histopathologic, and genetic findings from 21 individuals in 11 unrelated families, with nine different mutations, described as cases of intrauterine IPEX. Recurrent male fetal death (multigenerational in five families) due to hydrops in the midsemester of pregnancy was the commonest presentation (13/21). Noteworthy, in the affected families, there were only fetal- or perinatal-onset cases, with no affected individuals presenting milder forms with later-life manifestation. Most alive births were preterm (5/6). Skin desquamation and intrauterine growth restriction were observed in part of the cases. Fetal ultrasonography showed hyperechoic bowel or dilated bowel loops in the five cases with available imaging data. Histopathology showed multi-visceral infiltrates with T lymphocytes and other cells, including eosinophils, the pancreas being affected in most of the cases (11/21) and as early as at 18 weeks of gestational age. Regarding the nine FOXP3 mutations found in these cases, six determine protein truncation and three predictably impair protein function. Having found distinct presentations for the same FOXP3 mutation in different families, we resorted to the mouse system and showed that the scurfy mutation also shows divergent severity of phenotype and age of death in C57BL/6 and BALB/c backgrounds. We also reviewed age-of-onset data from other monogenic Tregopathies leading to IPEX-like phenotypes. In monogenic IPEX-like syndromes, the intrauterine onset was only observed in two kindreds with IL2RB mutations, with two stillbirths and two premature neonates who did not survive. In conclusion, intrauterine IPEX cases seem to constitute a particular IPEX subgroup, certainly with the most severe clinical presentation, although no strict mutation-phenotype correlations could be drawn for these cases.

The transcription factor FOXP3 controls the immunosuppressive program in CD4+ T cells that is crucial for systemic immune regulation. Mutations of the single X-chromosomal FOXP3 gene in male individuals cause the inherited autoimmune disease immune dysregulation, polyendocrinopathy, enteropathy, and X-linked (IPEX) syndrome. Insufficient gene expression and impaired function of mutant FOXP3 protein prevent the generation of anti-inflammatory regulatory T (Treg) cells and fail to inhibit autoreactive T cell responses. Diversification of FOXP3 functional properties is achieved through alternative splicing that leads to isoforms lacking exon 2 (FOXP3Δ2), exon 7 (FOXP3Δ7), or both (FOXP3Δ2Δ7) specifically in human CD4+ T cells. Several IPEX mutations targeting these exons or promoting their alternative splicing revealed that those truncated isoforms cannot compensate for the loss of the full-length isoform (FOXP3fl). In this review, IPEX mutations that change the FOXP3 isoform profile and the resulting consequences for the CD4+ T-cell phenotype are discussed.

Primary immunodeficiency disorders that predominantly affect immune regulation and mechanisms of self-tolerance have come into the limelight, because at least for a subgroup of monogenetic disorders, a targeted therapy has become available. Nevertheless, their management often involves the treatment of severely compromising, refractory, multi-organ autoimmunity, leading to further increased susceptibility to infections and complications of long-term immune suppressive treatment, including the risk of malignancy. While evidence for allogeneic hematopoietic stem cell transplantation (alloHSCT) as a curative treatment option for severely affected patients by this disease category accumulates, clear indications, and guidelines for alloHSCT are lacking. Predictive and stratification-relevant tools such as disease activity scores are largely missing and often there is not a consistent genotype-phenotype correlation within the same family to facilitate the decision whether to transplant or not. In this review, we provide a literature-based update on indications and outcomes of alloHSCT for congenital immune dysregulative inborn errors of immunity according to the IUIS classification 2017.

Immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome is a monogenic disorder caused by mutations in the FOXP3 gene, required for generation of regulatory T (T reg ) cells. Loss of T reg cells leads to immune dysregulation characterized by multi-organ autoimmunity and early mortality. Hematopoietic stem cell (HSC) transplantation can be curative, but success is limited by autoimmune complications, donor availability and/or graft-vs.-host disease. Correction of FOXP3 in autologous HSC utilizing a homology-directed repair (HDR)-based platform may provide a safer alternative therapy. Here, we demonstrate efficient editing of FOXP3 utilizing co-delivery of Cas9 ribonucleoprotein complexes and adeno-associated viral vectors to achieve HDR rates of >40% in vitro using mobilized CD34 + cells from multiple donors. Using this approach to deliver either a GFP or a FOXP3 cDNA donor cassette, we demonstrate sustained bone marrow engraftment of approximately 10% of HDR-edited cells in immune-deficient recipient mice at 16 weeks post-transplant. Further, we show targeted integration of FOXP3 cDNA in CD34 + cells from an IPEX patient and expression of the introduced FOXP3 transcript in gene-edited primary T cells from both healthy individuals and IPEX patients. Our combined findings suggest that refinement of this approach is likely to provide future clinical benefit in IPEX., Competing Interests: S.S., I.F.K, Y.H., K.M.S., and D.J.R hold provisional patent PCT WO2019210042 entitled “Expression of FOXP3 in edited CD34+ cells” related to this work. Another patent, “Expression of Human FOXP3 in Gene Edited T Cells,” has also been filed with Y.H., K.M.S., I.F.K, and D.J.R. as authors., (© 2023 The Author(s).)

Regulatory T (Treg) cells expressing the transcription factor forkhead box P3 (Foxp3) play a requisite role in the maintenance of immunological homeostasis and prevention of peripheral self-tolerance breakdown. Although Foxp3 by itself is neither necessary nor sufficient to specify many aspects of the Treg cell phenotype, its sustained expression in Treg cells is indispensable for their phenotypic stability, metabolic fitness, and regulatory function. In this review, we summarize recent advances in Treg cell biology, with a particular emphasis on the role of Foxp3 as a transcriptional modulator and metabolic gatekeeper essential to an effective immune regulatory response. We discuss these findings in the context of human inborn errors of immune dysregulation, with a focus on FOXP3 mutations, leading to Treg cell deficiency. We also highlight emerging concepts of therapeutic Treg cell reprogramming to restore tolerance in the settings of immune dysregulatory disorders. [ABSTRACT FROM AUTHOR]

Hyper IgE syndromes comprise a group of rare primary immunodeficiency disorders characterized by a triad of atopic dermatitis, recurrent skin and lung infections along with elevated IgE levels. Job syndrome or autosomal dominant hyper IgE syndrome because of heterozygous loss‐of‐function mutations with dominant negative effect in signal transducer and activator of transcription‐3 is the prototype of these disorders. However, several other genetically characterized immunodeficiency disorders have been identified over the past decade and joined the umbrella of hyper IgE syndromes including autosomal recessive mutations in the DOCK8,ZNF431 and PGM3 genes and heterozygous mutations with dominant negative effect in the CARD11 gene. Moreover, a number of phenotypically distinct immunodeficiency disorders can mimic hyper IgE syndromes, adding to the diagnostic challenge. Herein, we will concisely review these disorders, their molecular bases, highlighting key distinguishing clinical and laboratory findings and therapeutic options. [ABSTRACT FROM AUTHOR]

Autoimmune enteropathy (AIE) is a complex disease affecting both children and adults. Although associated with significant morbidity and mortality, the pathophysiology of the disease and its treatment have not been well characterized. This study aims to review the medical literature available on this rare but clinically significant ailment, to help establish a better understanding of its pathophysiology and enumerate the available diagnostic and treatment modalities. A literature search was conducted on PubMed using key terms related to autoimmune enteropathy and intractable diarrhea, with no restrictions on the date of publication or language. We found a total of 98 reports of AIE published in the form of case reports and case series. The evidence reviewed suggests that AIE is a multifaceted disorder that requires a high index of suspicion in the appropriate clinical setting to be able to make an early diagnosis. Current evidence supports the use of supportive care to correct nutritional and metabolic deficiencies, and immunosuppressives and immunomodulators as directed therapies. Hematopoietic stem cell transplant is an aggressive, but successful curative modality for patients with AIE as part of immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome. Cumulative clinical experience with management of AIE has allowed improved outcomes in transplanted and non-transplanted AIE patients even though morbidity and mortality with are still high in patients with this condition. More research is needed to further define the role of new therapies for AIE, and a central registry with participation of multiple institutions might help share and standardize care of patients with this rare but serious condition. [ABSTRACT FROM AUTHOR]

Summary: Recently, several studies have investigated a number of rare monogenic autoimmune disorders, in which the causative genetic defects were identified and found to affect the development or function of regulatory T cells (Tregs). The studies of these disorders have facilitated a deeper understanding of the mechanisms involved in immune regulation and tolerance. Furthermore, these studies have highlighted the importance of Tregs in maintaining homeostasis at the mucosal interface between the host and microbiome. Here, we offer our perspective on these monogenic autoimmune disorders, highlighting their overlapping clinical features with inflammatory bowel disease. [ABSTRACT FROM AUTHOR]

Abstract Early onset multisystem autoimmunity is commonly the defining feature of IPEX. Recurrent sinopulmonary infections and CVID-like phenotype were not previously recognized as a presentation in IPEX. Herein, we describe three extended family members with IPEX. In addition to autoimmunity, all three had a CVID-like presentation consisting of recurrent sinopulmonary infections, hypogammaglobulinemia and B-cell class switching defect. In vitro studies have shown that the B cell class switching defect is not B cell intrinsic. Additionally, a marked increase in circulating T follicular helper (cTFH) cells with high IFN-γ and IL-17 secretion on stimulation was noted in our patients. The dysregulated cTFH cells could contribute to a decreased B cell class switching. However, the exact mechanism of how expanded and dysregulated cTFH lead to B cell class switching defect and hypogammaglobulinemia in our patients is not clear. Our study could extend the clinical spectrum of IPEX to include a CVID-like presentation. Highlights • Autoimmunity is a known manifestation of immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome. • Recurrent sinopulmonary infections and hypogammaglobinemia are not well recognized in IPEX syndrome. • IPEX, as other disorders involving regulatory T cells, can include a common variable immunodeficiency (CVID)-like presentation. • Expanded but dysregulated cTFH and B cell class switching defect could contribute to the development of hypogammaglobulinemia in some IPEX patients. [ABSTRACT FROM AUTHOR]

The lack of a functional Foxp3 transcription factor and regulatory T (Treg) cells causes lethal, CD4+ T cell-driven autoimmune diseases in scurfy (SF) mice and humans. Recent studies have shown that adenosine A2A receptor activation limits inflammation and tissue damage, thereby playing an anti-inflammatory role. However, the role of the adenosine A2A receptor in the development of disease in SF mice remains unclear. Using a genetic approach, we found that adenosine A2A receptor deletion in SF mice (SF⋅A2A-/-) does not affect early life events, the development of a lymphoproliferative disorder, or hyper-production of pro-inflammatory cytokines seen in the Treg-deficiency state. As shown previously, Lactobacillus reuteri DSM 17938 treatment prolonged survival and reduced multiorgan inflammation in SF mice. In marked contrast, A2A receptor deletion completely blocked these beneficial effects of L. reuteri in SF mice. Altogether, these results suggest that although absence of the adenosine A2A receptor does not affect the development of disease in SF mice, it plays a critical role in the immunomodulation by L. reuteri in Treg-deficiency disease. The adenosine A2A receptor and its activation may have a role in treating other Treg dysfunction-mediated autoimmune diseases.

The interpretation of clinical diagnostic results in suspected inborn errors of immunity, including Tregopathies, is hampered by the lack of age-stratified reference values for regulatory T cells (Treg) in the pediatric population and a consensus on which Treg immunophenotype to use. Regulatory B cells (Breg) are an important component of the regulatory system that have been poorly studied in the pediatric population. We analyzed (1) the correlation between the three immunophenotypic definitions of Treg (CD4 + CD25 hi CD127 low , CD4 + CD25 hi CD127 low FoxP3 + , CD4 + CD25 hi FoxP3 + ), and with CD4 + CD25 hi and (2) the changes in Treg and Breg frequencies and their maturation status with age. We performed peripheral blood immunophenotyping of Treg and Breg (CD19 + CD24 hi CD38 hi ) by flow cytometry in 55 healthy pediatric controls. We observed that Treg numbers varied depending on the definition used, and the frequency ranged between 3.3-9.7% for CD4 + CD25 hi CD127 low , 0.07-1.6% for CD4 + CD25 hi CD127 low FoxP3 + , and 0.24-2.83% for CD4 + CD25 hi FoxP3 + . The correlation between the three definitions of Treg was positive for most age ranges, especially between the two intracellular panels and with CD4 + CD25 hi vs CD4 + CD25 hi CD127 low . Treg and Breg frequencies tended to decline after 7 and 3 years onwards, respectively. Treg's maturation status increased with age, with a decline of naïve Treg and an increase in memory/effector Treg from age 7 onwards. Memory Breg increased progressively from age 3 onwards. In conclusion, the number of Treg frequencies spans a wide range depending on the immunophenotypic definition used despite a good level of correlation exists between them. The decline in numbers and maturation process with age occurs earlier in Breg than in Treg., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2023 Luo, Acevedo, Vlagea, Codina, García-García, Deyà-Martínez, Martí-Castellote, Esteve-Solé and Alsina.)

Regulatory T cells (Tregs) are critical for enforcing peripheral tolerance. Monogenic "Tregopathies" affecting Treg development, stability, and/or function commonly present with polyautoimmunity, atopic disease, and infection. While autoimmune manifestations may present in early childhood, as more disorders are characterized, conditions with later onset have been identified. Treg numbers in the blood may be decreased in Tregopathies, but this is not always the case, and genetic testing should be pursued when there is high clinical suspicion. Currently, hematopoietic cell transplantation is the only curative treatment, but gene therapies are in development, and small molecule inhibitors/biologics may also be used., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Abstract Primary immunodeficiency diseases (PIDs) consist of a large group of genetic disorders that affect distinct components of the immune system. PID patients are susceptible to infection and non-infectious complications, particularly autoimmunity. A specific group of monogenic PIDs are due to mutations in genes that are critical for the regulation of immunological tolerance and immune responses. This group of monogenic PIDs is at high risk of developing polyautoimmunity (i.e., the presence of more than one autoimmune disease in a single patient) because of their impaired immunity. In this review, we discuss the mechanisms of autoimmunity in PIDs and the characteristics of polyautoimmunity in the following PIDs: IPEX; monogenic IPEX-like syndrome; LRBA deficiency; CTLA4 deficiency; APECED; ALPS; and PKCδ deficiency. [ABSTRACT FROM AUTHOR]