Autoinflammatory bone disorders: update on immunologic abnormalities and clues about possible triggers

SAPHO syndrome: current clinical, diagnostic and treatment approaches

This review provides an overview of SAPHO (Synovitis, Acne, Pustulosis, Hyperostosis, and Osteitis), a rare autoinflammatory disease that primarily affects bones, skin, and joints. We conducted a search on Medline/PubMed using keywords such as SAPHO syndrome, chronic recurrent multifocal osteitis/osteomyelitis, and related terms. SAPHO syndrome is rare, with a reported frequency of 1 in 10,000 in the Caucasian population. However, the actual incidence of SAPHO syndrome is unknown, and the incidence of the disease is likely higher. The pathogenesis of SAPHO syndrome remains incompletely understood. Current evidence suggests that SAPHO results from a complex interplay between immune dysregulation, genetic susceptibility, and environmental factors. It's not clear if SAPHO syndrome is an autoimmune disease or an autoinflammatory disease, but current evidence suggests that it's more likely an autoinflammatory disease because of things like neutrophil hyperactivity, fewer natural killer (NK) cells, high levels of interleukin (IL)-1, and a good response to treatments that block IL-1. Osteo-articular (OA) involvement is a key clinical feature of SAPHO. It affects the anterior chest wall, axial skeleton, peripheral joints, mandible, long bones of the extremities, and pelvis. Dermatological involvement is a common target in SAPHO, with lesions observed in 60-90% of cases. Common skin lesions include psoriasis and acne, with hidradenitis suppurativa and neutrophilic dermatoses being less commonly seen. Other clinical findings include constitutional symptoms caused by systemic inflammation, such as fever, weight loss, and fatigue. There is no specific laboratory finding for SAPHO syndrome. However, during active disease, there may be an increase in positive acute phase markers, such as erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), complement levels, mild leukocytosis, and thrombocytosis. Diagnosis is crucial for SAPHO syndrome, which lacks a specific diagnostic finding and is often underrecognized. A comprehensive evaluation of a patient's medical history and physical examination is crucial. Treatment options include non-steroidal anti-inflammatory drugs (NSAIDs), corticosteroids, conventional and synthetic disease-modifying agents (cDMARDs and sDMARDs), biological therapies, bisphosphonates, and antibiotics. Biological treatments have emerged as a viable alternative for SAPHO patients who do not respond to conventional treatments.

Skin manifestations help identifying different phenotypes of paediatric SAPHO syndrome

OBJECTIVES

to evaluate whether the heterogeneous skin manifestations might influence the disease presentation and outcome of a cohort of SAPHO children.

METHODS

the clinical, serological, imaging and therapeutic data of 14 SAPHO patients, followed between 2001 and 2022 at the Unit for Autoinflammatory diseases at the Gaslini Hospital, were reviewed. According to their cutaneous manifestations, patients were divided into 2 groups: the acne-hidradenitis suppurativa (HS) and the Palmo-Plantar Pustulosis (PPP) group. Data were retrieved from the Eurofever database.

RESULTS

all patients presented bone involvement characterized by Chronic Recurrent multifocal Osteomyelitis (CRMO): 8 patients presented acne-HS while 6 patients had PPP. In the PPP group, all patients were female, characterized by a prepuberal disease onset with osteoarticular manifestations, followed by the appearance of PPP in the following 6 months. This group responded well to the treatments. In the acne-HS group, 7/8 patients were male: the disease onset was characterized by skin manifestations in pubertal age, followed by osteoarticular manifestations in the following year. This group presented a severe refractory skin disease that required in most cases the addition of biological therapies. A literature review confirmed our data highlighting the association males-acne-puberal age and female-PPP-prepuberal age.

CONCLUSION

paediatric SAPHO patients should be mainly stratified according to their skin involvement. In fact, our data suggest that two different skin phenotypes may be identified in SAPHO: the first is constituted by prepuberal females with PPP and a prevalent osteoarticular involvement, while the second by puberal males with a difficult-to-treat acne-HS.

Chronic Recurrent Multifocal Osteomyelitis: A Comprehensive Literature Review

Chronic recurrent multifocal osteomyelitis (CRMO) is a non-infectious, inflammatory disorder of the bones. CRMO typically affects children, with a predisposition to females. Bone-related pain is often felt in the metaphysis of long bones, particularly of the lower extremities, but it can also target other sites at varied time intervals. Patients are likely to complain of tenderness and swelling that may cause considerable disability and adversely impact quality of life. There are three main pathophysiological mechanisms that have been hypothesized to drive CRMO including imbalanced cytokine expression, increased inflammasome activation, and enhanced osteoclast differentiation. Therapies have been based on targeting and suppressing these key players in CRMO patients. The first step in management involves pain control. Non-steroidal anti-inflammatory drugs should provide initial relief, albeit temporarily. It is imperative to initiate immunosuppressive medication that will help limit bone involvement and thereby prevent the development of fractures or leg-length discrepancies, for example. The purpose of this literature review is to study the pathophysiology of CRMO and carefully dissect the agents that have been previously employed in the management of CRMO patients. This could allow for the purposeful formulation of individualized care plans and improving the overall well-being of patients. The authors included a multitude of PubMed-indexed articles published from 2000 onwards in this review.

Presenting signs and clinical outcome in dogs with metaphyseal osteopathy: 39 cases (2009-2018)

OBJECTIVE

To describe the presenting signs, concurrent conditions, treatment and outcome of dogs with metaphyseal osteopathy.

MATERIALS AND METHODS

Multi-centre retrospective review of medical records from January 2009 to September 2018 at four referral centres to identify dogs with a radiographic diagnosis of metaphyseal osteopathy.

RESULTS

Thirty-nine dogs were identified. The median age at onset was 14 weeks old (range, 8 to 32 weeks old). There was a higher proportion of male dogs (29 of 39 male entire, nine of 39 female entire, one of 39 female neutered and no male neutered dogs). Where information was available, median time from the most recent vaccination was 20 days (range, 2 to 144 days). The most commonly recorded clinical signs were pyrexia (34 of 39), lethargy (32 of 39), pain (30 of 39), and being non-ambulatory (17 of 39). Thirty-five dogs required hospitalisation for analgesia and supportive care, 19 of 39 were discharged on prednisolone (median dose 2.0 mg/kg/day; range, 0.9 to 2.6 mg/kg/day), 18 of 39 were discharged on non-steroidal anti-inflammatories, two of 39 did not receive NSAIDs or prednisolone at any time point. The median duration of hospitalisation for those admitted was 5 days (range, 1 to 21 days). Where follow-up was available, relapse occurred in eight of 25 cases before reaching skeletal maturity. At the time of metaphyseal osteopathy diagnosis, five of 39 cases had concurrent conditions. Where follow-up was available, four of 25 developed future immune-mediated conditions.

CLINICAL SIGNIFICANCE

Metaphyseal osteopathy should be considered in non-ambulatory painful young dogs. Some dogs developed future immune-mediated conditions, which may support the hypothesis that metaphyseal osteopathy is an autoinflammatory bone disorder. Further studies with a larger cohort are required to determine the clinical significance of this.

Coincidence of pachydermoperiostosis and synovitis, acne, pustulosis, hyperostosis, osteitis syndrome, a causal or casual association?

Pachydermoperiostosis (PDP) is a rare disorder characterized by skin thickening, acropachia, and periostosis. Synovitis, acne, pustulosis, hyperostosis, osteitis (SAPHO) syndrome is also an orphan disease featured by different dermatological and osteoarthritic manifestations. Herein, we report the first case of an adolescent male diagnosed with both PDP and SAPHO syndrome, presenting with digital clubbing, polyarthralgia, ostealgia, pachydermia and acne on his face, chest and back. Furthermore, we distinguish the characteristics of both diseases and explore the potential pathological mechanism for this coexistence in one patient. Further investigations are needed to establish the detailed pathophysiological association of these 2 diseases.

Chronic recurrent multifocal osteomyelitis, a rare disease. Case report

Introduction: Chronic recurrent multifocal osteomyelitis (CRMO) is a rare inflammatory bone disease usually observed in children and adolescents. It is caused by an imbalance between proinflammatory and anti-inflammatory factors. To establish its diagnosis, it is necessary to integrate clinical and laboratory elements that are typically aimed at ruling out other conditions, constituting a diagnosis of exclusion. Treatment is based on non-steroidal anti-inflammatory drugs and other drugs in specific cases. Case presentation: A 16-year-old female patient with a 1-year history of joint pain, especially in the knees, accompanied by signs of local inflammation was admitted to the emergency department of a quaternary care hospital due to a fever >38.5°, odynophagia, asthenia, and adynamia over the last two days. The patient underwent multiple extension studies, including laboratory, imaging and histopathological tests, which ruled out various etiologic causes. She received empirical antibiotic treatment without remission of symptoms, so a diagnosis of CRMO was finally established and outpatient treatment with non-steroidal anti-inflammatory drugs and corticosteroids was indicated, obtaining a favorable response. Conclusions: CRMO should be considered in children and adolescents with bone pain and a poorly defined clinical history with non-specific laboratory, imaging and histopathological findings. To date, little is known about CRMO, so it is necessary to carry out research and expand the knowledge related to this disease.

Chronic Nonbacterial Osteomyelitis of the Sternocostoclavicular Region in Adults: A Single-Center Dutch Cohort Study

Sternocostoclavicular hyperostosis (SCCH) is a rare autoinflammatory bone disorder caused by chronic nonbacterial osteomyelitis (CNO), which is associated with sclerosis and hyperostosis primarily affecting the sternum, the medial end of the clavicles, and the first ribs. Other areas of the axial skeleton may also be affected. The more severe synovitis–acne–pustulosis–hyperostosis–osteitis (SAPHO) syndrome is additionally associated with dermatoses and joint manifestations. This Dutch retrospective cross‐sectional single‐center cohort study characterizes the spectrum of clinical features in adult CNO/SCCH patients at the time of diagnosis. The only inclusion criteria was the availability of complete sets of clinical and imaging data systematically collected over three decades using in‐house protocols. Data from 213 predominantly female patients (88%) with a median age of 36 years at presentation were studied. The mean diagnostic delay was 5 ± 5 years. The main symptoms were chronic pain (92%), bony swelling (61%), and restricted shoulder girdle function (46%); 32% had palmoplantar pustulosis and 22% had autoimmune disease. The majority (73%) had isolated SCCH; 59 (27%) had additional localizations in vertebrae (19%), the mandible (9%), or both (2%); 4 had SAPHO. The prevalence of current or past smoking was high (58%), particularly for patients with palmoplantar pustulosis (76%). There was a significant relationship between delay in diagnosis and both the extent of affected skeletal sites (p = 0.036) and erythrocyte sedimentation rate levels (p = 0.023). Adult‐onset CNO is characterized by distinctive clinical and radiological features, but diverse aspects of its spectrum are currently not fully captured by a comprehensive classification. Delayed diagnosis is still common and potentially associated with irreversible structural changes and debilitating chronic symptoms, increasing the burden of illness and negatively impacting on quality of life. It is hoped that findings from this study will dispel confusion about nomenclature and classification of adult‐onset CNO and increase awareness of its distinctive clinical and radiological features, and thus facilitate early diagnosis and referral for treatment, which should positively impact prognosis by preventing disease progression, although this remains to be established. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Coexistence of Sjögren syndrome in patients with synovitis, acne, pustulosis, hyperostosis, and osteitis syndrome: A retrospective observational study

To identify the prevalence and clinical characteristics of Sjögren syndrome (SS) in a Chinese single-center cohort of synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome.Patients diagnosed with SS were screened out from a cohort of 164 cases of SAHPO syndrome. Information regarding the patients' gender, age at onset, clinical features, laboratory tests, bone scintigraphy, and treatment was reviewed.Five patients were screened out. The prevalence of SS in SAPHO patients was 3.05% The mean onset age of SS was 48.0 ± 12.0 years old and no apparent time order in the occurrence of SAPHO and SS was observed. Compared with the general SAPHO cohort, the 5 SS patients exhibited no significant difference in the SAPHO related clinical features or inflammatory markers, except for a higher prevalence of peripheral joints and bones involvement in bone scintigraphy. Objective evidence of dryness and positive salivary gland biopsy were found in all the patients. However, the positive rates of SSA and SSB antibody were only 20%. Anti-inflammatory treatment for SS was recorded in 3 patients (ESSDAI score: 3 in 2 patients; 12 in 1 patient) with extra-glandular manifestations, severe complications or poor response to the basic treatment.The prevalence of SS is higher in the SAPHO cohort than in the general Chinese population. Objective tests or biopsy might be more indicative than the antibody detection for SS diagnosis. Anti-inflammatory treatment should be prescribed in consideration of both the severity of SS and the demand for disease activity control of SAPHO.

Genome-Wide Association Identifies Risk Pathways for SAPHO Syndrome

SAPHO syndrome is a rare chronic inflammatory disease which is characterized by the comprehensive manifestations of bone, joint, and skin. However, little is known about the pathogenesis of SAPHO syndrome. A genome-wide association study (GWAS) of 49 patients and 121 control subjects have primarily focused on identification of common genetic variants associated with SAPHO, the data were analyzed by classical multiple logistic regression. Later, GWAS findings were further validated using whole exome sequencing (WES) in 16 patients and 15 controls to identify potentially functional pathways involved in SAPHO pathogenesis. In general, 40588 SNPs in genomic regions were associated with P < 0.05 after filter process, only 9 SNPs meet the expected cut-off P-value, however, none of them had association with SAPHO syndrome based on published literatures. And then, 15 pathways were found involved in SAPHO pathogenesis, of them, 6 pathways including osteoclast differentiation, bacterial invasion of epithelial cells, et al., had strong association with skin, osteoarticular manifestations of SAPHO or inflammatory reaction based published research. This study identified aberrant osteoclast differentiation and other pathways were involved in SAPHO syndrome. This finding may give insight into the understanding of pathogenic genes of SAPHO and provide the basis for SAPHO research and treatment.

[Chronic multifocal osteomyelitis: A case report and literature review]

A case of chronic multifocal osteomyelitis was described in terms of its clinical manifestations, serological and imaging examinations, diagnostic criteria, treatment options, and follow-up evaluation after discharge. The pathogenesis, diagnosis, differential diagnosis and treatment of chronic multifocal osteomyelitis were reviewed, and the characteristics of autoinflammatory osteopathy were reviewed. The patient with onset from youth had developed severe skin lesions, progressive arthralgia and rachialgia. The clinical manifestation and the auxiliary examination of the patient accorded with the diagnosis of chronic multifocal osteomyelitis. After poor anti-inflammatory and analgesic effects, the switch to tumor necrosis factor alpha (TNF-α) inhibitor resulted in pain relief, normalization of inflammation indexes, and significant improvement in rash and imaging examination. Chronic recurrent multifocal osteomyelitis was a kind of autoinflammatory bone disease of multiple genes in disease with low incidence, unknown mechanism and unified diagnostic criteria. It was also known as chronic nonbacterial osteomyelitis, which was a rare, noninfectious inflammatory disorder that caused multifocallytic bone lesions characterized by periodic exacerbations and remissions. The exact pathophysiology or mechanism of the sterile bone inflammation was poorly understood, although chronic nonbacterial osteomyelitis was probably an osteoclast-mediated disease. In addition, an imbalance between pro- and anti-inflammatory cytokines was suspected to play a role. The available data so far pointed to the interplay among genetics, environmental, and immunologic factors as the causes of chronic nonbacterial osteomyelitis. Infectious etiology did not seem to play a crucial role in the pathogenesis of chronic nonbacterial osteomyelitis. It was often confused with metabolic bone disease, infection, tumor and other diseases. Its clinical manifestations were bone pain, fever, rash, fracture and so on. Laboratory examination showed significant increase in inflammatory markers. Radiographic examination revealed osteolytic or sclerosing changes. Magnetic resonance imaging was very useful for identifying bone lesions and tissue edema and was more accurate than bone emission computed tomography (ECT). Most of the patients begin to use non-steroidal anti-inflammatory drugs (NSAIDs) for treatment, but they are prone to relapse and new lesions appear. Other treatment options can be selected, including glucocorticoids, TNF-α inhibitors, bisphosphonates, methotrexate and other disease-modifying anti-rheumatic drugs (DMARDs). Early diagnosis and treatment can prevent and reduce complications and improve prognosis.

Copy Number Variation of Multiple Genes in SAPHO Syndrome

OBJECTIVE

SAPHO (synovitis, acne, pustulosis, hyperostosis, osteitis) syndrome is a type of rare chronic aseptic inflammation of unknown etiology. To date, no research to our knowledge has reported copy number variation (CNV) of genes that could affect predisposition to SAPHO syndrome. We investigated the association between CNV profile and SAPHO syndrome.

METHODS

We used array comparative genomic hybridization (CGH) to screen for CNV in a nuclear family including 2 patients and a healthy control. We then validated the copy numbers of candidate genes found in the array CGH assay and other candidate genes by TaqMan real-time PCR in 360 case and control samples.

RESULTS

Ten regions from 8 chromosomes were found to have abnormal gene copies in the nuclear family, so the CNV of candidate genes (ADAM5, CSF2RA, IL3RA, and 9 other genes) were tested by TaqMan PCR. Significant copy number loss of CSF2RA (p = 0.000) and NOD2 (p = 0.005), and significant copy number gain of MEGF6 (p = 0.002) and ADAM5 (p = 0.000) were seen in patients with SAPHO compared with controls at the a = 0.05 level. There were no differences in the other 8 candidate genes between patient and control samples (p > 0.05).

CONCLUSION

Our study established the first association between CNV in CSF2RA, NOD2, MEGF6, and ADAM5 and SAPHO syndrome. These findings may offer insight into the pathogenesis of SAPHO and provide the basis for improved diagnosis and treatment.

Association analysis of interleukin-23 receptor SNPs and SAPHO syndrome in Chinese people

OBJECTIVE

SAPHO syndrome (synovitis, acne, pustulosis, hyperostosis, and osteitis) is an autoimmune disease of unknown etiology that seriously affects patients' daily lives. Family-based investigations support genetic contributions toward disease susceptibility. The present study evaluated whether the previously reported autoimmune disease-associated single nucleotide polymorphisms (SNPs) have any genetic overlap with SAPHO syndrome.

METHOD

Genomic DNA was obtained from 71 SAPHO patients and 104 healthy controls. The SNP genotypes of each patient were determined with polymerase chain reaction and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Genotype, allele, and haplotype frequencies were analyzed with SPSS software.

RESULTS

Three SNP sites (rs10889677 and rs2201841 of interleukin [IL]-23R, and rs2243248 of IL-4) showed significant correlation with the occurrence of SAPHO syndrome in additive and dominant genetic models, while rs7517847 of IL-23R showed substantial correlation with SAPHO in the dominant genetic model. The G allele of rs2243248 (IL-4) was a high risk factor for SAPHO (P = 2.41e-5, odds ratio [OR] =7.79, 95% CI: 2.59-23.3). The haplotype (A-G-C-G-T), comprising 5 SNPs of the IL-23R gene, had a significantly higher frequency in the SAPHO cohort than in the controls (P = .011, OR = 2.05, 95% CI: 1.12-3.60).

CONCLUSION

Variants rs10889677, rs2201841, and rs7517847 of IL-23R, and variant rs2243248 of IL-4, showed strong associations with SAPHO syndrome. Patients carrying the A-G-C-G-T haplotype of IL-23 are significantly more likely to develop SAPHO syndrome.

Chronic non-bacterial osteomyelitis in the jaw

Chronic recurrent multifocal osteomyelitis (CRMO) is one of the most severe form of chronic non-bacterial osteomyelitis (CNO), which could result in bone and related tissue damage. This autoinflammatory bone disorder (ABD) is very difficult for its clinical diagnosis because of no diagnostic criteria or biomarkers. CRMO in the jaw must be suspected in the differential diagnosis of chronic and recurrent bone pain in the jaw, and a bone biopsy should be considered in chronic and relapsing bone pain with swelling that is unresponsive to treatment. The early diagnosis of CRMO in the jaw will prevent unnecessary and prolonged antibiotic usage or unnecessary surgical intervention. The updated researches for the identification of genetic and molecular alterations in CNO/CRMO should be studied more for its correct pathophysiological causes and proper treatment guidelines. Although our trial consisted of reporting items from Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), there are very few articles of randomized controlled trials. This article was summarized based on the author's diverse clinical experiences. This paper reviews the clinical presentation of CNO/CRMO with its own pathogenesis, epidemiology, recent research studies, and general medications. Treatment and monitoring of the jaw are essential for the clear diagnosis and management of CNO/CRMO patients in the field of dentistry and maxillofacial surgery.

The role of Cutibacterium acnes in auto-inflammatory bone disorders

Chronic nonbacterial osteomyelitis (CNO) and SAPHO (synovitis, acne, pustulosis, hyperostosis and osteitis) syndrome are auto-inflammatory disorders manifesting as chronic inflammation of bones and joints, which in SAPHO is often accompanying by skin changes. The aetiology of these diseases is unknown, but includes genetic, infectious and immunological components. It has been proposed that Cutibacterium (formerly Propionibacterium) acnes plays a role in the pathogenesis. In this review, we summarise reported cases of CNO or SAPHO syndrome in which C. acnes has been isolated from bones. To identify cases, a search was done in May 2018 using the MEDLINE Ovid interface (1946 to present). We found 14 publications reporting 98 patients with auto-inflammatory bone disorders, of whom 48 (49%) had positive bone biopsies for C. acnes. This bacterium was more frequently isolated from open biopsies than percutaneous ones (43/69 (62%) vs 1/7 (14%); p = 0.04) and biopsies were more frequently positive in patients who presented with simultaneous skin manifestations (19/36 (53%) vs 4/12 (33%); p = 0.03).Conclusion: In patients with CNO or SAPHO, C. acnes can be isolated from open biopsies suggesting that in these patients, C. acnes might be a pathogen rather than a contaminant. The fact that biopsies are more frequently positive in patients who present with simultaneous skin manifestations suggests that these individuals might have a genetic predisposition for impaired clearance of C. acnes. What is known • Chronic nonbacterial osteomyelitis (CNO) and SAPHO (synovitis, acne, pustulosis, hyperostosis and osteitis) syndrome are auto-inflammatory disorders manifesting as inflammation of bones. Both diseases are an important differential diagnosis in children who present with symptoms of (multifocal) osteomyelitis. • The pathogenesis of CNO and SAPHO is multifactorial emcompassing genetic, infectious and immunological components, including interleukin (IL)-1 dysregulation. There is a controversy as to whether Cutibacterium (formerly Propionibacterium) acnes plays a role in the aetiology of CNO and SAPHO. It has been postulated that the presence of C. acnes might trigger auto-inflammatory chronic inflammation in genetically predisposed individuals. What is new • In patients with CNO or SAPHO, C. acnes can be isolated more frequently from open biopsies, than from percutaneous ones, suggesting that C. acnes might be a pathogen rather than a contaminant. • Biopsies are more frequently positive in patients who present with simultaneous skin manifestations suggesting that these individuals might have a genetic predisposition for impaired clearance of C. acnes. Impaired C. acnes clearance likely leads to increased IL-1 beta (β) production by skin cells, bone cells and phagocytes, which is one of the main cytokines underlying chronic inflammatory bone disorders.

Chronic Recurrent Multifocal Osteomyelitis (CRMO): Presentation, Pathogenesis, and Treatment

PURPOSE OF REVIEW

Chronic non-bacterial osteomyelitis (CNO) with its most severe form chronic recurrent multifocal osteomyelitis (CRMO) is an autoinflammatory bone disorder. We summarize the clinical presentation, diagnostic approaches, most recent advances in understanding the pathophysiology, and available treatment options and outcomes in CNO/CRMO.

RECENT FINDINGS

Though the exact molecular pathophysiology of CNO/CRMO remains somewhat elusive, it appears likely that variable defects in the TLR4/MAPK/inflammasome signaling cascade result in an imbalance between pro- and anti-inflammatory cytokine expressions in monocytes from CNO/CRMO patients. In this context, we present previously unpublished data on cytokine and chemokine expression in monocytes and tissues. CNO/CRMO is an autoinflammatory bone disorder resulting from imbalanced cytokine expression from innate immune cells. Though the exact molecular pathophysiology remains unclear, variable molecular defects appear to result in inflammasome activation and pro-inflammatory cytokine expression in monocytes from CNO/CRMO patients. Recent advances suggest signaling pathways and single molecules as biomarkers for CNO/CRMO as well as future treatment targets.

Bivariate genome-wide association analyses identified genetic pleiotropic effects for bone mineral density and alcohol drinking in Caucasians

Several studies indicated bone mineral density (BMD) and alcohol intake might share common genetic factors. The study aimed to explore potential SNPs/genes related to both phenotypes in US Caucasians at the genome-wide level. A bivariate genome-wide association study (GWAS) was performed in 2069 unrelated participants. Regular drinking was graded as 1, 2, 3, 4, 5, or 6, representing drinking alcohol never, less than once, once or twice, three to six times, seven to ten times, or more than ten times per week respectively. Hip, spine, and whole body BMDs were measured. The bivariate GWAS was conducted on the basis of a bivariate linear regression model. Sex-stratified association analyses were performed in the male and female subgroups. In males, the most significant association signal was detected in SNP rs685395 in DYNC2H1 with bivariate spine BMD and alcohol drinking (P = 1.94 × 10^-8). SNP rs685395 and five other SNPs, rs657752, rs614902, rs682851, rs626330, and rs689295, located in the same haplotype block in DYNC2H1 were the top ten most significant SNPs in the bivariate GWAS in males. Additionally, two SNPs in GRIK4 in males and three SNPs in OPRM1 in females were suggestively associated with BMDs (of the hip, spine, and whole body) and alcohol drinking. Nine SNPs in IL1RN were only suggestively associated with female whole body BMD and alcohol drinking. Our study indicated that DYNC2H1 may contribute to the genetic mechanisms of both spine BMD and alcohol drinking in male Caucasians. Moreover, our study suggested potential pleiotropic roles of OPRM1 and IL1RN in females and GRIK4 in males underlying variation of both BMD and alcohol drinking.

How lipid droplets "TAG" along: Glycerolipid synthetic enzymes and lipid storage

Triacylglycerols (TAG) serve as the predominant form of energy storage in mammalian cells, and TAG synthesis influences conditions such as obesity, fatty liver, and insulin resistance. In most tissues, the glycerol 3-phosphate pathway enzymes are responsible for TAG synthesis, and the regulation and function of these enzymes is therefore important for metabolic homeostasis. Here we review the sites and regulation of glycerol-3-phosphate acyltransferase (GPAT), acylglycerol-3-phosphate acyltransferase (AGPAT), lipin phosphatidic acid phosphatase (PAP), and diacylglycerol acyltransferase (DGAT) enzyme action. We highlight the critical roles that these enzymes play in human health by reviewing Mendelian disorders that result from mutation in the corresponding genes. We also summarize the valuable insights that genetically engineered mouse models have provided into the cellular and physiological roles of GPATs, AGPATs, lipins and DGATs. Finally, we comment on the status and feasibility of therapeutic approaches to metabolic disease that target enzymes of the glycerol 3-phosphate pathway. This article is part of a Special Issue entitled: Recent Advances in Lipid Droplet Biology edited by Rosalind Coleman and Matthijs Hesselink.

Vasculitis in the autoinflammatory diseases

PURPOSE OF REVIEW

This article addresses the prevalence and relationship between autoinflammatory diseases and vasculitis.

RECENT FINDINGS

Autoimmune diseases (AIDs) are a group of syndromes characterized by episodes of unprovoked inflammation due to dysregulation of the innate immune system. Despite the common occurrence of rashes and other skin lesions in these diseases, vasculitis is reported in only a few. On the other hand, neutrophilic dermatoses are more prevalent. Large vessel vasculitis is reported in patients with Behcet's and Blau's syndromes. Small and medium size vasculitides are reported in familial Mediterranean fever mainly as Henoch-Schonlein purpura and polyarteritis nodosa, respectively. It is rarely described in hyper IgD with periodic fever syndrome, cryopyrin associated periodic syndromes, TNF receptor-associated periodic syndrome, deficiency of interleukin-1 receptor antagonist and pyoderma gangrenosum and acne syndrome. In most AID where bones and skin are mainly involved (CRMO, Majeed syndrome, Cherubism and DITRA) - vasculitis has not been described at all. In AID small vessel vasculitis affects mainly the skin with no involvement of internal organs.

SUMMARY

In AID, neutrophilic dermatoses are more common and prominent than vasculitis. This may reflect a minor role for interleukin-1 in the pathogenesis of vasculitis. The rarity of vasculitis in AID suggests that in most reported cases its occurrence has been probably coincidental rather than being an integral feature of the disease.

Treatment Response and Longterm Outcomes in Children with Chronic Nonbacterial Osteomyelitis

Objective.

The autoinflammatory bone disorder chronic nonbacterial osteomyelitis (CNO) covers a wide clinical spectrum, ranging from mild self-limited presentations to chronically active or recurrent courses, which are then referred to as chronic recurrent multifocal osteomyelitis (CRMO). Little is known about treatment options and longterm outcomes. We investigated treatment responses and outcomes in children with CNO.

Methods.

A retrospective chart review was conducted in a tertiary referral center, covering 2004–2015. Disease activity was measured at 0, 3, 6, 12, and 24 months after treatment initiation, and at the last recorded visit.

Results.

Fifty-six patients with CNO were identified; 44 had multifocal CNO. Fifty percent of patients relapsed after a median of 2.4 years, and as few as 40% remained relapse-free after 5 years. Nonsteroidal antiinflammatory drugs were used as first-line treatment in 55 patients, inducing remission after 3 months in all individuals with relapse rates of 50% after 2 years. Further treatment included corticosteroids (n = 23), tumor necrosis factor-α (TNF-α) inhibitors (n = 7), and bisphosphonates (n = 8). While 47% of patients with CNO relapsed within 1 year after corticosteroid therapy, favorable outcomes were achieved with TNF-α inhibitors or bisphosphonates (pamidronate).

Conclusion.

CNO is a chronic disease with favorable outcomes within the first year, but high relapse rates in longterm followup. Particularly, patients with CRMO with long-lasting, uncontrolled inflammation were at risk for the development of arthritis. Our findings underscore the importance of a timely diagnosis and treatment initiation. Prospective studies are warranted to establish evidence-based diagnostic and therapeutic approaches to CNO.

Serum levels of innate immunity cytokines are elevated in dogs with metaphyseal osteopathy (hypertrophic osteodytrophy) during active disease and remission

Metaphyseal osteopathy (MO) (hypertrophic osteodystrophy) is a developmental disorder of unexplained etiology affecting dogs during rapid growth. Affected dogs experience relapsing episodes of lytic/sclerotic metaphyseal lesions and systemic inflammation. MO is rare in the general dog population; however, some breeds (Weimaraner, Great Dane and Irish Setter) have a much higher incidence, supporting a hereditary etiology. Autoinflammatory childhood disorders of parallel presentation such as chronic recurrent multifocal osteomyelitis (CRMO), and deficiency of interleukin-1 receptor antagonist (DIRA), involve impaired innate immunity pathways and aberrant cytokine production. Given the similarities between these diseases, we hypothesize that MO is an autoinflammatory disease mediated by cytokines involved in innate immunity. To characterize immune dysregulation in MO dogs we measured serum levels of inflammatory markers in 26 MO and 102 control dogs. MO dogs had significantly higher levels (pg/ml) of serum Interleukin-1beta (IL-1β), IL-18, IL-6, Granulocyte-macrophage colony stimulating factor (GM-CSF), C-X-C motif chemokine 10 (CXCL10), tumor necrosis factor (TNF), and IL-10. Notably, recovered MO dogs were not different from dogs during active MO disease, providing a suggestive mechanism for disease predisposition. This is the first documentation of elevated immune markers in MO dogs, uncovering an immune profile similar to comparable autoinflammatory disorders in children.

Unexpectedly high incidences of chronic non-bacterial as compared to bacterial osteomyelitis in children

Historically, osteomyelitis was considered an infectious disorder. More recently, inflammatory mechanisms were recognized causing a significant proportion of pediatric osteomyelitis. This study was to compare characteristics of children with chronic non-bacterial (CNO) and bacterial osteomyelitis (BOM). A chart review of osteomyelitis patients from the departments of pediatrics, pediatric surgery, orthopedic surgery, and oral and maxillofacial surgery was conducted in a tertiary referral center, covering the years 2004-2014. Institutional incidences of CNO (n = 49) and BOM (n = 56) were comparable. Differentiation between CNO and BOM based on clinical or laboratory findings was mostly impossible. However, children with BOM more frequently presented with local inflammatory signs (47 vs. 68 %, p = 0.040), fever (12 vs. 38 %, p = 0.003), and abscesses (0 vs. 39 %, p < 0.001). Peripheral arthritis (14 vs. 0 %, p < 0.001), inflammatory bowel disease (10 vs. 2 %, p = ns), and hyperostosis (29 vs. 4 %, p = 0.001) were more common in CNO. Whole-body MRI was performed in 76 % of CNO patients, unveiling multifocal lesions in 80 % (CRMO). Though considered a rare disorder, institutional incidences of CNO were comparable to BOM, and the discrimination between CNO and BOM solely based on clinical aspects was mostly impossible. This is of special interest, since a correct and timely diagnosis is of utmost importance for long-term outcomes in both disorders. Whole-body MRIs should be considered in chronic osteomyelitis to (1) detect clinically inapparent lesions in CNO and (2) indirectly exclude (usually unifocal) chronic bacterial infections. Prospective studies are warranted to establish evidence-based diagnostic and therapeutic approaches to CNO.

Chronic Nonbacterial Osteomyelitis: Pathophysiological Concepts and Current Treatment Strategies

Chronic nonbacterial osteomyelitis (CNO) is an autoinflammatory bone disorder, covering a clinical spectrum with asymptomatic inflammation of single bones at the one end, and chronic recurrent multifocal osteomyelitis (CRMO) at the other end. The exact molecular pathophysiology of CNO remains largely unknown. Provided familial clusters and the association with inflammatory disorders of the skin and intestine suggest a genetic predisposition. Recently, profound dysregulation of cytokine responses was demonstrated in CRMO. Failure to produce antiinflammatory cytokines interleukin (IL)-10 and IL-19 contributes to activation of inflammasomes and subsequent IL-1β release. In IL-10-deficient and in CNO-prone chronic multifocal osteomyelitis mice, IL-1β was linked to bone inflammation. Further, alterations to the gut microbiome were suggested in contributing to IL-1β release from innate immune cells in mice, offering an interesting target in the search for molecular mechanisms in CNO. Here, we summarize clinical presentation and treatment options in CNO/CRMO, current pathophysiological concepts, available mouse models, and promising future scientific directions.

Neutrophils from patients with SAPHO syndrome show no signs of aberrant NADPH oxidase-dependent production of intracellular reactive oxygen species

Objective. We aimed to investigate if aberrant intracellular production of NADPH oxidase-derived reactive oxygen species (ROS) in neutrophils is a disease mechanism in the autoinflammatory disease SAPHO syndrome, characterized by synovitis, acne, pustulosis, hyperostosis and osteitis, as has previously been suggested based on a family with SAPHO syndrome-like disease.

Methods. Neutrophil function was explored in a cohort of four patients with SAPHO syndrome, two of whom were sampled during both inflammatory and non-inflammatory phase. Intracellular neutrophil ROS production was determined by luminol-amplified chemiluminescence in response to phorbol myristate acetate.

Results. Cells from all patients produced normal amounts of ROS, both intra- and extracellularly, when compared with internal controls as well as with a large collection of healthy controls assayed in the laboratory over time (showing an extensive inter-personal variability in a normal population). Further, intracellular production of ROS increased during the inflammatory phase. Neutrophil activation markers were comparable between patients and controls.

Conclusion. Dysfunctional generation of intracellular ROS in neutrophils is not a generalizable feature in SAPHO syndrome. Secondly, serum amyloid A appears to be a more sensitive inflammatory marker than CRP during improvement and relapses in SAPHO syndrome.

Primary Chronic Osteomyelitis of the Jaws in Children: An Update on Pathophysiology, Radiological Findings, Treatment Strategies, and Prospective Analysis of Two Cases

Objective. Primary chronic osteomyelitis (PCO) of the jaws in children is associated with pain, trismus, and swelling. In children, temporomandibular joint involvement is rare and few studies have been published due to the relatively low incidence. This paper presents two cases of mandibular PCO in children with the involvement of the collum mandibulae. In addition, a review of the literature regarding demographic data, histological, radiological, and laboratory findings, and treatment strategies of PCO was also performed. Material and Methods. Prospective analyses of two PCO cases. A PubMed search was used and the articles were sorted according to their corresponding key area of focus. Results. Review of the literature revealed twenty-four cases of PCO with two cases of mandibular condyle involvement. The mean age was 18 years; the male to female ratio was 1 : 3. Most of the patients were treated with anti-inflammatory drugs in combination with decortication. Clinical recurrence was seen in 7 cases. Conclusion. A combination of anti-inflammatory drugs and surgical intervention appears to be the first choice of treatment. However, surgical removal of necrotic tissue adjacent to collum mandibulae has its limitations in children. Further investigations are of utmost importance in order to increase our knowledge and understanding of this disease.

Characteristics and outcomes of chronic non-bacterial osteitis in children

OBJECTIVE

To determine patient characteristics, clinical presentation, pattern of involvement, treatment, and outcome of patients with chronic non-bacterial osteitis (CNO).

MATERIAL AND METHODS

Consecutive cases of CNO were analyzed at a single center for pediatrics and adolescent medicine from 2006 to 2013 in terms of patient characteristics, clinical presentation, pattern of involvement, treatment, and outcome.

RESULTS

We identified 32 children aged 1.5-15 years who were diagnosed with CNO between 2006 and 2013. A maximum of 12 bones per patient were affected in a total of 114 documented locations. The pelvis and clavicle (affecting 34% of patients each) were the most frequently affected bones. The foot skeleton was the most commonly affected region in 60% of patients. Skin manifestations were found in 7 (21%) patient. Increased inflammatory signs at presentation were detected in 18 patients. Pathological findings were found in all 30 children examined using magnetic resonance imaging (MRI), in 10 of 11 children examined using radiography, and in 8 of 10 patients examined using skeletal scintigraphy. Bone biopsy was performed in 9 patients. For initial treatment, non-steroidal anti-inflammatory drugs (NSAIDs) or coxibs were used in 28 (87.5%) patients. Remission or satisfactory follow-up was achieved in all patients.

CONCLUSION

Today, CNO is increasingly diagnosed using MRI and rarely through histological examinations. Therapeutic strategies include NSAIDs, which are often highly effective. All patients in the present study showed good clinical outcomes.

Skull involvement in a pediatric case of chronic recurrent multifocal osteomyelitis

An 11-year-old boy was diagnosed with chronic recurrent multifocal osteomyelitis (CRMO) and presented with right sacro-femoral and occipital lesions. Initially, a tumor was suspected. However, the bone biopsy showed osteomyelitis with a negative bacterial culture. Bone scintigraphy revealed inflammatory changes on multiple bone lesions. The slight elevation in inflammatory markers such as C-reactive protein was of little clinical value. He was diagnosed with CRMO by sacral biopsy, and the clinical course progressed, with the presence of a new occipital lesion observed after the 1-year follow-up. The administration of non-steroidal anti-inflammatory drugs successfully improved his clinical symptoms. The presence of a skull lesion in the occipital bone of a pediatric patient with CRMO has not been previously reported.

New discoveries in CRMO: IL-1β, the neutrophil, and the microbiome implicated in disease pathogenesis in Pstpip2-deficient mice

Chronic non-bacterial osteomyelitis (CNO), chronic recurrent multifocal osteomyelitis (CRMO) and synovitis, acne, pustulosis, hyperostosis and osteitis (SAPHO) syndrome are autoinflammatory disorder(s) in which sterile osteomyelitis is frequently accompanied by inflammatory conditions of the joints, skin, or intestine. Patients with CRMO commonly have a personal or family history of psoriasis, inflammatory bowel disease, and inflammatory arthritis, suggesting shared disease pathogenesis. Work by our group and others has demonstrated that dysregulation of interleukin-1 (IL-1) signaling can drive sterile osteomyelitis in the two human monogenic forms of the disease. Recent work in the chronic multifocal osteomyelitis (cmo) mouse model demonstrates that the disease is IL-1-mediated, that neutrophils are critical effector cells and that both caspase-1 and caspase-8 play redundant roles in mediating the cleavage of pro-IL-1β into its biologically active form. Recent data in the cmo mouse demonstrate that dietary manipulation alters the cmo microbiome and can prevent the development of osteomyelitis. Further investigation is needed to determine the specific components of the diet that result in protection from disease and if this finding can be translated into a treatment for human CRMO.

The role of IL-1β in the bone loss during rheumatic diseases

Several inflammatory diseases have been associated with increased bone resorption and fracture rates and different studies supported the relation between inflammatory cytokines and osteoclast activity. The main factor required for osteoclast activation is the stimulation by receptor activator of nuclear factor kappa-B ligand (RANKL) expressed on osteoblasts. In this context, interleukin- (IL-) 1β, one of the most powerful proinflammatory cytokines, is a strong stimulator of in vitro and in vivo bone resorption via upregulation of RANKL that stimulates the osteoclastogenesis. The resulting effects lead to an imbalance in bone metabolism favouring bone resorption and osteoporosis. In this paper, we review the available literature on the role of IL-1β in the pathogenesis of bone loss. Furthermore, we analysed the role of IL-1β in bone resorption during rheumatic diseases and, when available, we reported the efficacy of anti-IL-1β therapy in this field.

Caseous granuloma: tuberculosis or chronic recurrent multifocal osteomyelitis?

BACKGROUND

Chronic recurrent multifocal osteomyelitis (CREMO) is one of the autoinflammatory bone disorders due to disturbance in innate immune system. Up to now, there is no reported case of caseous granulomas in the CREMO. We report a boy with sterile granolumatous osteomyelitis.

CASE PRESENTATION

A four-year-old boy presented with swelling and pain in the left wrist, malaise and bilateral erythematous pustulosis on the palmar region which had resolved spontaneously after about 7 days. The histopathology of the lesions showed severe acute and chronic inflammatory process and chronic granulomatous reaction with caseating necrosis (granulomatous osteomyelitis). The direct smear, culture and PCR for the mycobacterium tuberculosis and atypical mycobacteria were negative. About five months after initiation of the anti-mycobacterial treatment, he was referred to the rheumatology clinic with left elbow pain, effusion and decreased range of motion, and bilateral erythematous palmar pustulosis. He was diagnosed as CREMO based on two exacerbations, repeatedly negative cultures, and concomitant acute and chronic lesions in the histopathology and X-ray. Naproxen and pamidronate every 3 months were started and all other medications were stopped. Two months after the first dose of pamidronate, he became symptom-free and forearm X-ray showed disappearance of the osteolytic lesions and periosteal reactions.

CONCLUSION

The diagnosis of CREMO should be considered in the patients with lytic bone lesions. In addition, the clinicians should be aware of the possibility of caseating granuloma in the cases with possible diagnosis of CREMO.

New players driving inflammation in monogenic autoinflammatory diseases

Systemic autoinflammatory diseases are caused by abnormal activation of the cells that mediate innate immunity. In the past two decades, single-gene defects in different pathways, driving clinically distinct autoinflammatory syndromes, have been identified. Studies of these aberrant pathways have substantially advanced understanding of the cellular mechanisms that contribute to mounting effective and balanced innate immune responses. For example, mutations affecting the function of cytosolic immune sensors known as inflammasomes and the IL-1 signalling pathway can trigger excessive inflammation. A surge in discovery of new genes associated with autoinflammation has pointed to other mechanisms of disease linking innate immune responses to a number of basic cellular pathways, such as maintenance of protein homeostasis (proteostasis), protein misfolding and clearance, endoplasmic reticulum stress and mitochondrial stress, metabolic stress, autophagy and abnormalities in differentiation and development of myeloid cells. Although the spectrum of autoinflammatory diseases has been steadily expanding, a substantial number of patients remain undiagnosed. Next-generation sequencing technologies will be instrumental in finding disease-causing mutations in as yet uncharacterized diseases. As more patients are reported to have clinical features of autoinflammation and immunodeficiency or autoimmunity, the complex interactions between the innate and adaptive immune systems are unveiled.

Inborn errors of metabolism underlying primary immunodeficiencies

A number of inborn errors of metabolism (IEM) have been shown to result in predominantly immunologic phenotypes, manifesting in part as inborn errors of immunity. These phenotypes are mostly caused by defects that affect the (i) quality or quantity of essential structural building blocks (e.g., nucleic acids, and amino acids), (ii) cellular energy economy (e.g., glucose metabolism), (iii) post-translational protein modification (e.g., glycosylation) or (iv) mitochondrial function. Presenting as multisystemic defects, they also affect innate or adaptive immunity, or both, and display various types of immune dysregulation. Specific and potentially curative therapies are available for some of these diseases, whereas targeted treatments capable of inducing clinical remission are available for others. We will herein review the pathogenesis, diagnosis, and treatment of primary immunodeficiencies (PIDs) due to underlying metabolic disorders.

Autoinflammatory bone disorders with special focus on chronic recurrent multifocal osteomyelitis (CRMO)

Sterile bone inflammation is the hallmark of autoinflammatory bone disorders, including chronic nonbacterial osteomyelitis (CNO) with its most severe form chronic recurrent multifocal osteomyelitis (CRMO). Autoinflammatory osteopathies are the result of a dysregulated innate immune system, resulting in immune cell infiltration of the bone and subsequent osteoclast differentiation and activation. Interestingly, autoinflammatory bone disorders are associated with inflammation of the skin and/or the intestine. In several monogenic autoinflammatory bone disorders mutations in disease-causing genes have been reported. However, regardless of recent developments, the molecular pathogenesis of CNO/CRMO remains unclear.Here, we discuss the clinical presentation and molecular pathophysiology of human autoinflammatory osteopathies and animal models with special focus on CNO/CRMO. Treatment options in monogenic autoinflammatory bone disorders and CRMO will be illustrated.