- Email: [email protected]
Cerebrospinal Fluid Neopterin and Cryopyrin-Associated Periodic Syndrome
Cerebrospinal Fluid Neopterin and Cryopyrin-Associated Periodic Syndrome
Serrano M, Ormaza´bal A, Anto´n J, Aro´stegui JI, Garcı´aCazorla A. Cerebrospinal fluid neopterin and cryopyrinassociated periodic syndrome. Pediatr Neurol 2009;41: 448-450.
Introduction
Cryopyrin-associated periodic syndrome is a category of autoinflammatory disorders caused by mutations of the NLRP3 gene, with chronic infantile neurologic cutaneous and articular syndrome being the severest clinical phenotype. Various pterins have been reported as mediating immunologic functions in the central nervous system, but to date studies of pterin cerebrospinal fluid (CSF) values and cryopyrin-associated periodic syndrome have been lacking. A 2-year-old child was affected with a severe atypical form of cryopyrin-associated periodic syndrome, suspected based on the analysis of neopterin in CSF. He initially presented isolated neurologic manifestations mimicking a neuroregressive disorder. Blood and CSF analyses did not present any routine inflammatory markers, but CSF neopterin was elevated. Later, the patient developed arthritis and recurrent episodes of fever, and the cryopyrin-associated periodic syndrome diagnosis was confirmed by genetic studies. Neopterin was the most altered indicator over the time. Child neurologists should be on the alert when unexplained neurologic signs appear, giving consideration to the possibility of inflammatory or immune-mediated diseases. The present case demonstrates the clinical utility of measurement of CSF neopterin levels in screening for these immune-mediated diseases, especially when neurologic symptoms are associated with normal results on routine CSF tests. Ó 2009 by Elsevier Inc. All rights reserved.
Cryopyrin-associated periodic syndrome is a category of dominantly-inherited autoinflammatory disorders caused by mutations of the NLRP3 gene on the long arm of chromosome 1 (previously CIAS1; alias PYPAF1, NALP3). Three apparently distinct clinical entities are included among cryopyrin-associated periodic syndromes, each one representing a different degree of severity along a clinical continuum. Thus, familial cold autoinflammatory syndrome (OMIM #120100) (http://www.ncbi.nlm.nih.gov) is at the mild end, Muckle-Wells syndrome (OMIM #191900) represents the intermediate phenotype, and chronic infantile neurologic cutaneous and articular syndrome (CINCA syndrome) (OMIM #607115), also known as neonatal-onset multisystem inflammatory disease (NOMID), is the severest clinical phenotype. Chronic infantile neurologic cutaneous and articular syndrome patients suffer from an early onset severe chronic inflammatory disease, characterized by urticaria-like skin rash, central nervous system impairment, and joint symptoms, usually associated with recurrent fever and systemic inflammation [1]. Neurologic impairment results from a chronic polymorphonuclear cell infiltration, and the main clinical manifestations include chronic aseptic meningitis, cerebral atrophy, uveitis, highfrequency hearing loss, and varying degrees of mental retardation in some patients [1]. The majority of cases of chronic infantile neurologic cutaneous and articular syndrome are sporadic. Mutational studies have revealed that 50-55% of patients carry mutations in the NLRP3 gene, most of them de novo mutations [2]. Therefore, 45-50% of patients do not appear to carry any mutation on this gene, despite exhaustive genetic research, suggesting the presence of genetic heterogeneity among types of chronic infantile neurologic cutaneous and articular syndrome [2]. The NLRP3 gene encodes a cytosolic protein named cryopyrin (also known as Nalp3) that forms a dynamic cytosolic multiprotein complex, termed Nalp3-inflammasome, with several different proteins, and
From the Departments of *Neurology and †Clinical Biochemistry and the ‡Rheumatology Unit, Hospital ‘‘Sant Joan de De´u,’’ University of Barcelona, Barcelona, Spain; the ¶Center for Biomedical Research on Rare Diseases (CIBERER), Institute of Health ‘‘Carlos III,’’ Barcelona, Spain; and the §Department of Immunology, CDB, Hospital Clinic, Clinical Foundation for Biomedical Research, Barcelona, Spain.
Communications should be addressed to: Dr. Serrano; Pediatric Neurology Department; Hospital Sant Joan de De´u; Passeig de Sant Joan de De´u, 2; 08950 Esplugues de Llobregat; Barcelona, Spain. E-mail: [email protected] Received February 25, 2009; accepted June 30, 2009.
Mercedes Serrano, MD, PhD*¶, Aida Ormaza´bal, PhD†¶, Jordi Anto´n, MD, PhD‡, Juan I. Aro´stegui, MD, PhD§, and ` ngels Garcı´a-Cazorla, MD, PhD*¶ A
448 PEDIATRIC NEUROLOGY Vol. 41 No. 6
Ó 2009 by Elsevier Inc. All rights reserved. doi:10.1016/j.pediatrneurol.2009.06.008 0887-8994/09/$—see front matter
which regulates the production of the active forms of interleukin-1b and interleukin-18, thereby playing a pivotal role in the innate immune response and in inflammation. In certain clinical settings, neopterin has been demonstrated to be a sensitive indicator of cellular immune activation that can provide valuable information in addition to routine cerebrospinal fluid (CSF) markers [3,4]. Described here is the case of a 2-year-old child affected with a severe atypical form of cryopyrin-associated periodic syndrome in which some of the clinical manifestations resembled those described in chronic infantile neurologic cutaneous and articular syndrome, which had been suspected based on the analysis of neopterin in CSF. Case Report A 21-month-old boy, the only child of healthy nonconsanguineous parents, was referred because of psychomotor regression. Perinatal history was uneventful. His early development was appropriate, presenting ocular pursuit at 1-2 months, social smile at 2-3 months, and head control at 3 months. He sat unsupported at 7-8 months and, around the age of 12 months, could stand momentarily without support. From that age onward, however, the child gradually lost these developmental milestones. After a period of about 3 months, the patient could not sit unsupported, had no head control, and was not able to pick up objects. Neurologic examination at 21 months of age revealed normal cranial circumference, without dysmorphic features. He presented truncal hypotonia, spastic tetraparesia, hyperreflexia, and extensor plantar reflexes. He was able to say some words and had good social interaction. At that point, to try to exclude progressive leukodystrophies (which would explain this regressive course starting at 1 year of age with prominent pyramidal involvement, as in metachromatic leukodystrophy), magnetic resonance imaging of the brain and upper spinal cord was performed; this testing revealed mild ventricular enlargement of the frontal horns, with no other abnormality. Ocular examination, acoustic examinations and electroencephalographic study all yielded normal results. Nerve conduction examination was performed to exclude regressive disorders associated with peripheral neuropathy, such as infantile neuroaxonal dystrophy, and findings were normal. To exclude the possibility of lysosomal diseases, as well as some rare intermediate metabolic pathway disturbances presenting with a similar clinical picture (e.g., arginase deficiency), screening tests were performed for inborn errors of metabolism (plasma lactate, pyruvate, ammonia, amino acids, isoelectric focusing pattern of transferrin, urine organic acids, glycosaminoglycans); these also yielded normal results. At the age of 21/2 years, the patient’s parents sought help because of his recurrent fever and because of ankle pain due to arthritis, which prevented him from standing or walking. Laboratory findings indicated leukocytosis (18,800/mL) with no neutrophilia, no eosinophilia (32% neutrophils, 58% lymphocytes, 0% eosinophils), and no thrombocytosis (maximum, 360,000/mL). C-reactive protein levels were always less than 5 mg/L (normal, <15 mg/L), erythrocyte sedimentation rate was elevated (maximum, 57 mm/hour; normal, <15 mm/hour), and amino transferase values were increased (maximum aspartate aminotransferase, 176 U/L; maximum alanine aminotransferase, 275 U/L). Gammagraphy indicated a diffuse increased signal in both ankles. No evidence of infection was noted, and no benefit from antibiotic treatment was achieved. Findings from cellular and humoral studies, complement levels, high titer of autoantibodies, and microbiological studies performed were normal or negative. Because of the lack of diagnosis at this point, and in light of the neurologic involvement, CSF study was performed. Lumbar puncture revealed no signs of intracranial hypertension; there was no increased cellularity (10/mL), and both protein levels (33 mg/dL; normal range, 15-40 mg/dL) and glucose levels were normal (2.7 mmol/L; normal range, 2.2-3.4 mmol/L). Amino acids in CSF revealed no abnormalities. Because of the
negative findings from these routine CSF tests, biogenic amine metabolites (homovanillic and 5-hydroxyindoleacetic acids) and pterins (neopterin and biopterin) were analyzed by reverse-phase high-performance liquid chromatography with electrochemical and fluorescence detection, as previously described [5]. This analysis indicated normal biogenic amine metabolites, but mildly elevated levels of biopterin (49 nmol/L; age-normal range, 1139 nmol/L) and highly elevated levels of neopterin (154 nmol/L; age-normal range, 8-43 nmol/L). In light of the presence of severe central nervous system manifestations, the recurrent arthritis and fever, and the laboratory data indicating an intense inflammatory condition (elevated erythrocyte sedimentation rate and high levels of CSF neopterin), DNA analysis for multisystemic inflammatory diseases was performed. For this purpose, the written informed consent of the patient’s parents and approval of the ethical committee of Hospital Clinic and Hospital Sant Joan de De´u were obtained. Mutational analysis of all coding exons of the NLRP3 gene revealed a heterozygous G-to-A transition at nucleotide position 592, on exon 3 of the gene, which provokes the missense amino acid substitution Val-198-Met (V198 M). This genetic result, previously reported to cause cryopyrin-associated periodic syndrome [6,7], led to the diagnosis. In accord with the medical reports about therapeutic approaches in cryopyrin-associated periodic syndrome, the patient’s parents were informed of the therapeutic options, and treatment with subcutaneous anakinra was begun at 1 mg/kg per day. After 5 months of treatment, no satisfying clinical response was obtained and the anakinra dose was progressively increased, to 5 mg/kg per day. After 8 months of treatment, blood test findings were entirely normal, but CSF analysis still indicated elevated neopterin levels (124 nmol/L; age-normal range, 9-55 nmol/L); this was the only increased inflammation marker. In follow-up monitoring to date, there has been only mild neurologic clinical response to anakinra. Nonetheless, after the initiation of treatment no more episodes of arthritis have occurred; regarding fever episodes, only febricula has been noticeable.
Discussion The clinical presentation of cryopyrin-associated periodic syndrome is usually characterized by a neonatal-onset urticaria-like skin rash, which can be accompanied by recurrent fever, arthritis or arthropathy, and central nervous system involvement. Moreover, manifestations can vary both in severity and in terms of atypical symptoms. In the present case, the atypical clinical presentation (which delayed the definitive diagnosis) was characterized by the presence of isolated neurologic manifestations for 8 months, which mimicked a neuroregressive disorder, with a progressive spastic tetraparesia and the loss of motor skills. Similar neurologic manifestations have previously been reported in a patient harboring NLRP3, but neurologic symptoms were detected some months after the appearance of an erythematous nodular rash [8]. V198 M mutation has been described as inducing cryopyrin-associated periodic syndrome with a heterogeneous phenotype [6,7]. Furthermore, in the reported cases with V198 M, headache has been the only neurologic symptom described. In the present case, blood tests indicated no inflammatory changes until the systemic inflammation process began with the ankle arthritis, probably because of the predominant and almost exclusive involvement of the central nervous system at the beginning. Later, blood test demonstrated nonspecific inflammatory changes such as leukocytosis and elevated erythrocyte sedimentation rate (maximum, 57 mm/hour; normal values, <15 mm/hour); surprisingly, C-reactive
Serrano et al: Neopterin and CAPS 449
protein levels were normal. During the entire evolution of the disease, CSF analysis revealed no inflammatory marker when routine tests were performed. Cryopyrin-associated periodic syndromes have been associated with gain-of-function mutations in the NLRP3 gene, which encodes cryopyrin. This protein belongs to the nod-like receptor family, and it senses both exogenous and endogenous danger signals (e.g., bacterial RNA and toxins, urate crystals) [9]. Once activated, cryopyrin forms the Nalp3 inflammasome by complexing with different proteins, and it stimulates production of the active forms of interleukin-1b and interleukin-18, playing an important role in the innate immune response and in inflammation [10,11]. Patients with cryopyrin-associated periodic syndromes present systemic inflammatory reactions attributed to increased serum concentrations of C-reactive protein, serum amyloid A, and various inflammatory cytokines (e.g., interleukin-1b, interleukin-6, interleukin-18, and tumor necrosis factor) [11]. Various pterins have been reported as mediating neurologic and immunologic functions in the central nervous system. Neopterin is a pyrazino-pyrimidine compound derived from guanosine triphosphate that is released from activated macrophages, and its production is inducible by different cytokines [4]. The clinical utility of CSF levels of neopterin in the diagnosis or monitoring of pediatric neurologic or rheumatologic diseases has been demonstrated [3,4,12]. In neuropediatrics, neopterin determination is particularly helpful to rule out infectious diseases in the CNS, Aicardi-Goutie`res syndrome, and some primary neurotransmitter diseases (e.g., Segawa syndrome, sepiapterin reductase deficiency). There have, however, been no previous studies of neopterin CSF values and cryopyrin-associated periodic syndromes. In the case reported, CSF levels of neopterin were the most altered marker over time, taking into account all the analyses performed. Even when partial clinical response was achieved with anakinra, neopterin CSF values remained increased, representing at that time the only increased inflammatory marker. Increased urine excretion of neopterin has been demonstrated in patients with different inflammatory diseases. As previous studies have demonstrated, however, neopterin concentration in CSF and serum or urine neopterin concentrations are not correlated [3], which is probably explained by the intrathecal production of neopterin. In the present case, repeated urine analyses of neopterin documented normal values (2.39 mmol neopterin/mol creatinine and 1.52 mmol neopterin/mol creatinine; normal range, 0.365.01 mmol neopterin/mol creatinine), whereas CSF analyses showed persistently increased neopterin levels. In summary, child neurologists, on the alert when unexplained neurologic signs appear, need to consider the
450 PEDIATRIC NEUROLOGY Vol. 41 No. 6
possibility of inflammatory or immune-mediated diseases. Because these diseases are highly variable in their clinical presentation, definitive diagnosis represents a major challenge. The present case demonstrates the clinical utility of measurement of CSF neopterin levels for these immunemediated diseases, which could provide valuable information, especially when neurologic symptoms are associated with normal results on the routine CSF tests. The authors thank Rafael Artuch for his help with the preparation of the manuscript and Dr. Jordi Yagu¨e for his help with molecular and immunologic studies. This study was supported by Fund for Health of Spain (FIS) grant PI051318, FIS grant PI060241, the national Ministry of Health (Ministerio de Sanidad y Consumo), and the Center for Biomedical Research on Rare Diseases (CIBERER) (ISC III).
References [1] Prieur AM, Griscelli C, Lampert F, et al. A chronic, infantile, neurological, cutaneous and articular (CINCA) syndrome: a specific entity analysed in 30 patients. Scand J Rheumatol Suppl 1987;66:57-68. [2] Aksentijevich I, Nowak M, Mallah M, et al. De novo CIAS1 mutations, cytokine activation, and evidence for genetic heterogeneity in patients with neonatal-onset multisystem inflammatory disease (NOMID): a new member of the expanding family of pyrin-associated autoinflammatory diseases. Arthritis Rheum 2002;46:3340-8. [3] Azumagawa K, Suzuki S, Tanabe T, Wakamiya E, Kawamura N, Tamai H. Neopterin, biopterin, and nitric oxide concentrations in the cerebrospinal fluid of children with central nervous system infections. Brain Dev 2003;25:200-2. [4] Huber C, Batchelor JR, Fuchs D, et al. Immune response-associated production of neopterin: release from macrophages primarily under control of interferon-gamma. J Exp Med 1984;160:310-6. [5] Ormazabal A, Garcı´a-Cazorla A, Ferna´ndez Y, Ferna´ndez´ lvarez E, Campistol J, Artuch R. HPLC with electrochemical and fluoresA cence detection procedures for the diagnosis of inborn errors of biogenic amines and pterins. J Neurosci Methods 2005;142:153-8. [6] Hoffman HM, Mueller JL, Broide DH, Wanderer AA, Kolodner RD. Mutation of a new gene encoding a putative pyrin-like protein causes familial cold autoinflammatory syndrome and Muckle-Wells syndrome. Nat Genet 2001;29:301-5. [7] Po¨rksen G, Lohse P, Ro¨sen-Wolff A, et al. Periodic fever, mild arthralgias, and reversible moderate and severe organ inflammation associated with the V198 M mutation in the CIAS1 gene in three German patients: expanding phenotype of CIAS1 related autoinflammatory syndrome. Eur J Haematol 2004;73:123-7. [8] Ting TV, Scalzi LV, Hashkes PJ. Nonclassic neurologic features in cryopyrin-associated periodic syndromes. Pediatr Neurol 2007;36: 338-41. [9] Martinon F, Petrilli V, Mayor A, Tardivel A, Tschopp J. Goutassociated uric acid crystals activate NALP3 inflammasome. Nature 2006;440:237-41. [10] Fritz JH, Ferrero RL, Philpott DJ, Girardin SE. Nod-like proteins in immunity, inflammation and disease. Nat Immunol 2006;7:1250-7. [11] Agostini L, Martinon F, Burns K, McDermott MF, Hawkins PN, Tschopp J. NALP3 forms an IL-1b-processing inflammasome with increased activity in Muckle-Wells autoinflammatory disorder. Immunity 2004;20:319-25. [12] Rice G, Patrick T, Parmar R, et al. Clinical and molecular phenotype of Aicardi-Goutie`res syndrome. Am J Hum Genet 2007;81:713-25.
Serrano M, Ormaza´bal A, Anto´n J, Aro´stegui JI, Garcı´aCazorla A. Cerebrospinal fluid neopterin and cryopyrinassociated periodic syndrome. Pediatr Neurol 2009;41: 448-450.
Introduction
Cryopyrin-associated periodic syndrome is a category of autoinflammatory disorders caused by mutations of the NLRP3 gene, with chronic infantile neurologic cutaneous and articular syndrome being the severest clinical phenotype. Various pterins have been reported as mediating immunologic functions in the central nervous system, but to date studies of pterin cerebrospinal fluid (CSF) values and cryopyrin-associated periodic syndrome have been lacking. A 2-year-old child was affected with a severe atypical form of cryopyrin-associated periodic syndrome, suspected based on the analysis of neopterin in CSF. He initially presented isolated neurologic manifestations mimicking a neuroregressive disorder. Blood and CSF analyses did not present any routine inflammatory markers, but CSF neopterin was elevated. Later, the patient developed arthritis and recurrent episodes of fever, and the cryopyrin-associated periodic syndrome diagnosis was confirmed by genetic studies. Neopterin was the most altered indicator over the time. Child neurologists should be on the alert when unexplained neurologic signs appear, giving consideration to the possibility of inflammatory or immune-mediated diseases. The present case demonstrates the clinical utility of measurement of CSF neopterin levels in screening for these immune-mediated diseases, especially when neurologic symptoms are associated with normal results on routine CSF tests. Ó 2009 by Elsevier Inc. All rights reserved.
Cryopyrin-associated periodic syndrome is a category of dominantly-inherited autoinflammatory disorders caused by mutations of the NLRP3 gene on the long arm of chromosome 1 (previously CIAS1; alias PYPAF1, NALP3). Three apparently distinct clinical entities are included among cryopyrin-associated periodic syndromes, each one representing a different degree of severity along a clinical continuum. Thus, familial cold autoinflammatory syndrome (OMIM #120100) (http://www.ncbi.nlm.nih.gov) is at the mild end, Muckle-Wells syndrome (OMIM #191900) represents the intermediate phenotype, and chronic infantile neurologic cutaneous and articular syndrome (CINCA syndrome) (OMIM #607115), also known as neonatal-onset multisystem inflammatory disease (NOMID), is the severest clinical phenotype. Chronic infantile neurologic cutaneous and articular syndrome patients suffer from an early onset severe chronic inflammatory disease, characterized by urticaria-like skin rash, central nervous system impairment, and joint symptoms, usually associated with recurrent fever and systemic inflammation [1]. Neurologic impairment results from a chronic polymorphonuclear cell infiltration, and the main clinical manifestations include chronic aseptic meningitis, cerebral atrophy, uveitis, highfrequency hearing loss, and varying degrees of mental retardation in some patients [1]. The majority of cases of chronic infantile neurologic cutaneous and articular syndrome are sporadic. Mutational studies have revealed that 50-55% of patients carry mutations in the NLRP3 gene, most of them de novo mutations [2]. Therefore, 45-50% of patients do not appear to carry any mutation on this gene, despite exhaustive genetic research, suggesting the presence of genetic heterogeneity among types of chronic infantile neurologic cutaneous and articular syndrome [2]. The NLRP3 gene encodes a cytosolic protein named cryopyrin (also known as Nalp3) that forms a dynamic cytosolic multiprotein complex, termed Nalp3-inflammasome, with several different proteins, and
From the Departments of *Neurology and †Clinical Biochemistry and the ‡Rheumatology Unit, Hospital ‘‘Sant Joan de De´u,’’ University of Barcelona, Barcelona, Spain; the ¶Center for Biomedical Research on Rare Diseases (CIBERER), Institute of Health ‘‘Carlos III,’’ Barcelona, Spain; and the §Department of Immunology, CDB, Hospital Clinic, Clinical Foundation for Biomedical Research, Barcelona, Spain.
Communications should be addressed to: Dr. Serrano; Pediatric Neurology Department; Hospital Sant Joan de De´u; Passeig de Sant Joan de De´u, 2; 08950 Esplugues de Llobregat; Barcelona, Spain. E-mail: [email protected] Received February 25, 2009; accepted June 30, 2009.
Mercedes Serrano, MD, PhD*¶, Aida Ormaza´bal, PhD†¶, Jordi Anto´n, MD, PhD‡, Juan I. Aro´stegui, MD, PhD§, and ` ngels Garcı´a-Cazorla, MD, PhD*¶ A
448 PEDIATRIC NEUROLOGY Vol. 41 No. 6
Ó 2009 by Elsevier Inc. All rights reserved. doi:10.1016/j.pediatrneurol.2009.06.008 0887-8994/09/$—see front matter
which regulates the production of the active forms of interleukin-1b and interleukin-18, thereby playing a pivotal role in the innate immune response and in inflammation. In certain clinical settings, neopterin has been demonstrated to be a sensitive indicator of cellular immune activation that can provide valuable information in addition to routine cerebrospinal fluid (CSF) markers [3,4]. Described here is the case of a 2-year-old child affected with a severe atypical form of cryopyrin-associated periodic syndrome in which some of the clinical manifestations resembled those described in chronic infantile neurologic cutaneous and articular syndrome, which had been suspected based on the analysis of neopterin in CSF. Case Report A 21-month-old boy, the only child of healthy nonconsanguineous parents, was referred because of psychomotor regression. Perinatal history was uneventful. His early development was appropriate, presenting ocular pursuit at 1-2 months, social smile at 2-3 months, and head control at 3 months. He sat unsupported at 7-8 months and, around the age of 12 months, could stand momentarily without support. From that age onward, however, the child gradually lost these developmental milestones. After a period of about 3 months, the patient could not sit unsupported, had no head control, and was not able to pick up objects. Neurologic examination at 21 months of age revealed normal cranial circumference, without dysmorphic features. He presented truncal hypotonia, spastic tetraparesia, hyperreflexia, and extensor plantar reflexes. He was able to say some words and had good social interaction. At that point, to try to exclude progressive leukodystrophies (which would explain this regressive course starting at 1 year of age with prominent pyramidal involvement, as in metachromatic leukodystrophy), magnetic resonance imaging of the brain and upper spinal cord was performed; this testing revealed mild ventricular enlargement of the frontal horns, with no other abnormality. Ocular examination, acoustic examinations and electroencephalographic study all yielded normal results. Nerve conduction examination was performed to exclude regressive disorders associated with peripheral neuropathy, such as infantile neuroaxonal dystrophy, and findings were normal. To exclude the possibility of lysosomal diseases, as well as some rare intermediate metabolic pathway disturbances presenting with a similar clinical picture (e.g., arginase deficiency), screening tests were performed for inborn errors of metabolism (plasma lactate, pyruvate, ammonia, amino acids, isoelectric focusing pattern of transferrin, urine organic acids, glycosaminoglycans); these also yielded normal results. At the age of 21/2 years, the patient’s parents sought help because of his recurrent fever and because of ankle pain due to arthritis, which prevented him from standing or walking. Laboratory findings indicated leukocytosis (18,800/mL) with no neutrophilia, no eosinophilia (32% neutrophils, 58% lymphocytes, 0% eosinophils), and no thrombocytosis (maximum, 360,000/mL). C-reactive protein levels were always less than 5 mg/L (normal, <15 mg/L), erythrocyte sedimentation rate was elevated (maximum, 57 mm/hour; normal, <15 mm/hour), and amino transferase values were increased (maximum aspartate aminotransferase, 176 U/L; maximum alanine aminotransferase, 275 U/L). Gammagraphy indicated a diffuse increased signal in both ankles. No evidence of infection was noted, and no benefit from antibiotic treatment was achieved. Findings from cellular and humoral studies, complement levels, high titer of autoantibodies, and microbiological studies performed were normal or negative. Because of the lack of diagnosis at this point, and in light of the neurologic involvement, CSF study was performed. Lumbar puncture revealed no signs of intracranial hypertension; there was no increased cellularity (10/mL), and both protein levels (33 mg/dL; normal range, 15-40 mg/dL) and glucose levels were normal (2.7 mmol/L; normal range, 2.2-3.4 mmol/L). Amino acids in CSF revealed no abnormalities. Because of the
negative findings from these routine CSF tests, biogenic amine metabolites (homovanillic and 5-hydroxyindoleacetic acids) and pterins (neopterin and biopterin) were analyzed by reverse-phase high-performance liquid chromatography with electrochemical and fluorescence detection, as previously described [5]. This analysis indicated normal biogenic amine metabolites, but mildly elevated levels of biopterin (49 nmol/L; age-normal range, 1139 nmol/L) and highly elevated levels of neopterin (154 nmol/L; age-normal range, 8-43 nmol/L). In light of the presence of severe central nervous system manifestations, the recurrent arthritis and fever, and the laboratory data indicating an intense inflammatory condition (elevated erythrocyte sedimentation rate and high levels of CSF neopterin), DNA analysis for multisystemic inflammatory diseases was performed. For this purpose, the written informed consent of the patient’s parents and approval of the ethical committee of Hospital Clinic and Hospital Sant Joan de De´u were obtained. Mutational analysis of all coding exons of the NLRP3 gene revealed a heterozygous G-to-A transition at nucleotide position 592, on exon 3 of the gene, which provokes the missense amino acid substitution Val-198-Met (V198 M). This genetic result, previously reported to cause cryopyrin-associated periodic syndrome [6,7], led to the diagnosis. In accord with the medical reports about therapeutic approaches in cryopyrin-associated periodic syndrome, the patient’s parents were informed of the therapeutic options, and treatment with subcutaneous anakinra was begun at 1 mg/kg per day. After 5 months of treatment, no satisfying clinical response was obtained and the anakinra dose was progressively increased, to 5 mg/kg per day. After 8 months of treatment, blood test findings were entirely normal, but CSF analysis still indicated elevated neopterin levels (124 nmol/L; age-normal range, 9-55 nmol/L); this was the only increased inflammation marker. In follow-up monitoring to date, there has been only mild neurologic clinical response to anakinra. Nonetheless, after the initiation of treatment no more episodes of arthritis have occurred; regarding fever episodes, only febricula has been noticeable.
Discussion The clinical presentation of cryopyrin-associated periodic syndrome is usually characterized by a neonatal-onset urticaria-like skin rash, which can be accompanied by recurrent fever, arthritis or arthropathy, and central nervous system involvement. Moreover, manifestations can vary both in severity and in terms of atypical symptoms. In the present case, the atypical clinical presentation (which delayed the definitive diagnosis) was characterized by the presence of isolated neurologic manifestations for 8 months, which mimicked a neuroregressive disorder, with a progressive spastic tetraparesia and the loss of motor skills. Similar neurologic manifestations have previously been reported in a patient harboring NLRP3, but neurologic symptoms were detected some months after the appearance of an erythematous nodular rash [8]. V198 M mutation has been described as inducing cryopyrin-associated periodic syndrome with a heterogeneous phenotype [6,7]. Furthermore, in the reported cases with V198 M, headache has been the only neurologic symptom described. In the present case, blood tests indicated no inflammatory changes until the systemic inflammation process began with the ankle arthritis, probably because of the predominant and almost exclusive involvement of the central nervous system at the beginning. Later, blood test demonstrated nonspecific inflammatory changes such as leukocytosis and elevated erythrocyte sedimentation rate (maximum, 57 mm/hour; normal values, <15 mm/hour); surprisingly, C-reactive
Serrano et al: Neopterin and CAPS 449
protein levels were normal. During the entire evolution of the disease, CSF analysis revealed no inflammatory marker when routine tests were performed. Cryopyrin-associated periodic syndromes have been associated with gain-of-function mutations in the NLRP3 gene, which encodes cryopyrin. This protein belongs to the nod-like receptor family, and it senses both exogenous and endogenous danger signals (e.g., bacterial RNA and toxins, urate crystals) [9]. Once activated, cryopyrin forms the Nalp3 inflammasome by complexing with different proteins, and it stimulates production of the active forms of interleukin-1b and interleukin-18, playing an important role in the innate immune response and in inflammation [10,11]. Patients with cryopyrin-associated periodic syndromes present systemic inflammatory reactions attributed to increased serum concentrations of C-reactive protein, serum amyloid A, and various inflammatory cytokines (e.g., interleukin-1b, interleukin-6, interleukin-18, and tumor necrosis factor) [11]. Various pterins have been reported as mediating neurologic and immunologic functions in the central nervous system. Neopterin is a pyrazino-pyrimidine compound derived from guanosine triphosphate that is released from activated macrophages, and its production is inducible by different cytokines [4]. The clinical utility of CSF levels of neopterin in the diagnosis or monitoring of pediatric neurologic or rheumatologic diseases has been demonstrated [3,4,12]. In neuropediatrics, neopterin determination is particularly helpful to rule out infectious diseases in the CNS, Aicardi-Goutie`res syndrome, and some primary neurotransmitter diseases (e.g., Segawa syndrome, sepiapterin reductase deficiency). There have, however, been no previous studies of neopterin CSF values and cryopyrin-associated periodic syndromes. In the case reported, CSF levels of neopterin were the most altered marker over time, taking into account all the analyses performed. Even when partial clinical response was achieved with anakinra, neopterin CSF values remained increased, representing at that time the only increased inflammatory marker. Increased urine excretion of neopterin has been demonstrated in patients with different inflammatory diseases. As previous studies have demonstrated, however, neopterin concentration in CSF and serum or urine neopterin concentrations are not correlated [3], which is probably explained by the intrathecal production of neopterin. In the present case, repeated urine analyses of neopterin documented normal values (2.39 mmol neopterin/mol creatinine and 1.52 mmol neopterin/mol creatinine; normal range, 0.365.01 mmol neopterin/mol creatinine), whereas CSF analyses showed persistently increased neopterin levels. In summary, child neurologists, on the alert when unexplained neurologic signs appear, need to consider the
450 PEDIATRIC NEUROLOGY Vol. 41 No. 6
possibility of inflammatory or immune-mediated diseases. Because these diseases are highly variable in their clinical presentation, definitive diagnosis represents a major challenge. The present case demonstrates the clinical utility of measurement of CSF neopterin levels for these immunemediated diseases, which could provide valuable information, especially when neurologic symptoms are associated with normal results on the routine CSF tests. The authors thank Rafael Artuch for his help with the preparation of the manuscript and Dr. Jordi Yagu¨e for his help with molecular and immunologic studies. This study was supported by Fund for Health of Spain (FIS) grant PI051318, FIS grant PI060241, the national Ministry of Health (Ministerio de Sanidad y Consumo), and the Center for Biomedical Research on Rare Diseases (CIBERER) (ISC III).
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