Serum levels of proinflammatory, anti-inflammatory cytokines, and RANKL/OPG in synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome

Clinical and imaging features of six Han patients with SAPHO syndrome

BACKGROUND

Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome is a rare autoimmune disease characterized by skin or osteoarticular damage. SAPHO syndrome is often misdiagnosed or missed diagnosis due to lack of overall understanding of the disease by clinicians.

PURPOSE

To analyze the clinical symptoms and imaging features of six Han patients with SAPHO syndrome in order to provide reference for doctors to diagnose SAPHO syndrome.

MATERIAL AND METHODS

This study retrospectively analyzed the clinical data of six Han patients with SAPHO syndrome.

RESULTS

All six Han patients with SAPHO syndrome had severe acne or pustulosis of the hands and feet, and all of them had osteoarticular damage, including five cases involving the sternoclavicular joint. Some patients showed a specific and typical "bull's head" sign on 99mTc-labeled methylene diphosphonate bone imaging. Among the six patients recruited, there was one thoracic vertebra, one cervical vertebra, one sacroiliac joint, and one peripheral joint involvement. Two patients had limited activity due to severe osteoarticular damage.

CONCLUSION

Due to the atypical clinical symptoms of SAPHO syndrome, most patients will experience a tortuous and long diagnostic process, while a correct understanding and timely intervention of SAPHO syndrome are essential to improve the prognosis of patients.

The clinical characteristics and prognosis of patients with SAPHO syndrome--a real-world cohort study

OBJECTIVES

We aimed to analyze the clinical characteristics and outcomes of patients with synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome.

METHODS

The clinical records of 64 patients with SAPHO syndrome were collected, and the treatment and outcomes of 27 patients were followed up. The patients were divided into three groups according to the site of bone lesions: only anterior chest wall (ACW) involvement, only spinal involvement, and bone lesion involvement at both sites. The clinical characteristics and outcomes were compared. The clinical characteristics of the patients with and without peripheral joint involvement were compared.

RESULTS

Among all patients, 31.25% (20/64) had only ACW involvement, 15.63% (10/64) had only spinal involvement, and 53.12% (34/64) had both ACW and spinal involvement. Peripheral joint involvement was observed in 25.00% (16/64) of the patients. Patients with only spinal involvement were older than those with only ACW involvement (p = 0.006). Patients with both ACW and spinal involvement were older than those with only ACW involvement (p = 0.002) and had a longer diagnosis delay (p = 0.015). Patients with peripheral joint involvement were younger than those without peripheral joint involvement (p = 0.028). During follow-up, 88.89% (24/27) of patients had good outcomes. Twenty-two patients were treated with non-steroidal anti-inflammatory drugs + Iguratimod (IGU), and the outcomes of 90.91% (20/22) improved.

CONCLUSIONS

A relationship may exist between the sites of bone lesions and clinical characteristics of patients with SAPHO syndrome. The clinical outcomes of these patients may be good, and IGU may be effective in treating SAPHO syndrome. Key Points • This study is the first long-term follow-up on the effectiveness of iguratimod in treating patients with SAPHO. • This study revealed that patients with SAPHO and different bone lesion sites may present with different clinical characteristics.

Immunological Characterization of Chronic Nonbacterial Osteomyelitis (CNO) in Adults: A Cross-Sectional Exploratory Study

Chronic nonbacterial osteomyelitis (CNO) is a rare disease spectrum affecting children and adults. Adult CNO may occur as isolated bone inflammation, or with a broad range of extraskeletal features. CNO pathophysiology, including the key drivers of inflammation, remains largely unknown. For pediatric CNO, a role for pro-inflammatory cytokine dysregulation has been proposed, but studies in adults are scarce. We therefore provide immunological characterization of adult CNO. Cross-sectional study in our referral center including adult CNO patients (n = 172) and healthy controls (n = 65). Inflammation parameters and systemic inflammatory based scores(SIBS, including neutrophil/lymphocyte ratio [NLR] and systemic immune inflammation index [SII]) were compared between groups. Cytokine expression was explored with electrochemiluminescent immunoassays in 33 patients, eight healthy controls and 21 osteoporosis patients. Routine inflammation markers were higher in patients than in controls, but generally remained within reference range. Systemic inflammation was more pronounced in patients with additional vertebral involvement as compared to those osteitis in the anterior chest wall alone, in patients with comorbid pustulosis palmoplantaris or psoriasis, and in patients with strongly rather than moderately increased lesional uptake on nuclear imaging. SII was elevated in CNO patients too, but NLR was not. Cytokine expression was generally nondifferential between patients and both control groups, and patients displayed low absolute concentrations of pro-inflammatory cytokines. In this adult CNO cohort, systemic inflammation was generally subtle, but more pronounced in patients with vertebral lesions, associated skin disease, and strongly increased uptake on nuclear imaging. SII was increased in patients compared to healthy controls. Contrasting pediatric studies, we found no increased expression of the pro-inflammatory cytokines that have been proposed to drive the inflammatory cascade, like interleukin-6, -8, and -17 (IL-6, IL-8, and IL-17), and tumor necrosis α (TNF-α). Further studies are needed to evaluate the use of SII in diagnosis and monitoring of CNO, and elucidate the role of cytokine dysregulation in adult disease. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.

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.

Dermatologic Manifestations of Noninflammasome-Mediated Autoinflammatory Diseases

Autoinflammatory diseases (AIDs) arise from disturbances that alter interactions of immune cells and tissues. They give rise to prominent (auto)inflammation in the absence of aberrant autoantibodies and/or autoreactive T cells. AIDs that are predominantly caused by changes in the inflammasome pathways, such as the NLRP3- or pyrin-associated inflammasome, have gained substantial attention over the last years. However, AIDs resulting primarily from other changes in the defense system of the innate immune system are less well-studied. These noninflammasome-mediated AIDs relate to, for example, disturbance in the TNF or IFN signaling pathways or aberrations in genes affecting the IL-1RA. The spectrum of clinical signs and symptoms of these conditions is vast. Thus, recognizing early cutaneous signs constitutes an important step in differential diagnoses for dermatologists and other physicians. This review provides an overview of the pathogenesis, clinical presentation, and available treatment options highlighting dermatologic aspects of noninflammasome-mediated AIDs.

RANKL Is Independently Associated with Increased Risks of Non-Alcoholic Fatty Liver Disease in Chinese Women with PCOS: A Cross-Sectional Study

Women with polycystic ovarian syndrome (PCOS) are more likely to have non-alcoholic fatty liver disease (NAFLD) than non-PCOS women; however, the exact mechanism underlying this trend is unknown. The receptor activator of NF-κB ligand (RANKL) is strongly involved in bone metabolism and has multiple functions. Recent studies suggest that RANKL is implicated in hepatic insulin resistance (IR), which is the highest risk factor for NAFLD. This study aimed to assess the role of RANKL in NAFLD in Chinese women with PCOS. A cross-sectional observational study was conducted on women newly diagnosed with PCOS, which included 146 patients with NAFLD and 142 patients without NAFLD. Sex hormones, glucose, insulin, and lipids were measured, and anthropometric data were collected. The concentration of serum total RANKL was measured using commercial ELISA kits. PCOS patients with NAFLD had a significantly higher mean age, body mass index (BMI), waist circumference (WC), and worsened metabolic profile than non-NAFLD subjects. The concentrations of high-sensitivity C-reactive protein, total cholesterol, and low-density lipoprotein cholesterol increased with the RANKL tertile (p for trend = 0.023, 0.026, and 0.035, respectively). A significantly positive association was found between RANKL (per SD change) and the risks of NAFLD (OR = 1.545, 95% CI = 1.086−2.199) after adjusting for confounders, including demographic factors, metabolic markers, and sex hormones. Subgroup multivariate logistic analyses stratified by age, BMI, and WC showed the same tendency. In addition, the positive association between RANKL and NAFLD seemed more prominent in lean patients with a BMI < 24 kg/m2 (OR = 1.70, 95% CI = 1.06−2.75) when compared to overweight/obesity subjects. Therefore, this study suggests that RANKL is positively associated with the increased risk of NAFLD in Chinese women with PCOS, independent of metabolic and reproductive factors.

New insights on multigenic autoinflammatory diseases

Autoinflammatory diseases are disorders of the innate immune system, which can be either monogenic due to a specific genetic mutation or complex multigenic due to the involvement of multiple genes. The aim of this review is to explore and summarize the recent advances in pathogenesis, diagnosis, and management of genetically complex autoinflammatory diseases, such as Schnitzler's syndrome; adult-onset Still's disease; synovitis, acne, pustulosis, hyperostosis, osteitis syndrome/chronic recurrent multifocal osteomyelitis/chronic non-bacterial osteomyelitis; Adamantiades-Behçet's disease; Yao syndrome; and periodic fever with aphthous stomatitis, pharyngitis, and adenitis syndrome. The PubMed database was screened for relevant articles using free text words and specific search strings. The search was limited to English-language articles, reporting the results of studies in humans, published through March 2021. Evidence from literature suggest that these rare multigenic autoinflammatory diseases can present with different clinical features and the diagnosis of these diseases can be challenging due to a combination of nonspecific manifestations that can be seen in a variety of other conditions. Diagnostic delays and disease complications may occur due to low disease awareness and the lack of pathognomonic markers. The pathogeneses of these diseases are complex and in some cases precise pathogenesis is not clearly understood. Conventional treatments are commonly used for the management of these conditions, but biologics have shown promising results. Biologics targeting proinflammatory cytokines including IL-1, IL-6, TNF-α, IL-17A and IL-18 have been shown to ameliorate signs and symptoms of different multigenic autoinflammatory diseases.

Pro and contra: is synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) a spondyloarthritis variant?

PURPOSE OF REVIEW

The purpose of this review is to present the up-to-date evidence on the epidemiology, pathogenesis, musculoskeletal manifestations, and imaging of the synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome and to discuss its relationship with spondyloarthritis (SpA).

RECENT FINDINGS

SAPHO is a rare inflammatory disorder of bone, joints, and skin, with a worldwide distribution that predominantly affects the middle-age adults. The hallmark of the syndrome is a constellation of sterile inflammatory osteitis, hyperostosis, and synovitis involving the anterior chest wall, associated with acneiform and neutrophilic dermatoses, such as palmoplantar pustulosis and severe acne. The axial skeleton, sacroiliac, and peripheral joints can be involved in a similar fashion to SpA. The pathogenesis of the syndrome is multifactorial. The diagnosis is mainly based on the clinical and typical radiological features. The treatment approach is based on the off-label use of antibiotics, bisphosphonates, disease-modifying antirheumatic drugs, and anticytokine biologics.

SUMMARY

The SAPHO syndrome shares common features with SpA-related diseases, yet also shows some unique pathogenetic and clinical features. The nosology of SAPHO remains a subject of controversy, awaiting further research into the pathogenetic and clinical aspects of this syndrome. A better understanding of these aspects will improve the diagnostics and clinical care of patients with SAPHO.

New Insights in the Treatment of SAPHO Syndrome and Medication Recommendations

Synovitis, acne, pustulosis, hyperostosis, osteitis (SAPHO) syndrome is a rare autoinflammatory disease characterized by dermatological disorders and osteoarticular inflammatory lesions. This article reviews the application of biologics and other treatments based on the therapeutic target and the size of molecules in SAPHO syndrome. We found that drugs, especially biologics, have different effects on bone, joint, and skin damage. This may relate to the different inflammatory pathways involved in the osteoarticular and cutaneous symptoms in SAPHO patients. In this study, we provide stratified medication recommendations for SAPHO syndrome. Patients with osteoarticular symptoms can consider tumor necrosis factor blockers, JAK inhibitor, interleukin (IL)-1 inhibitor, and IL-17 inhibitor. Patients with cutaneous symptoms should consider IL-17 and JAK inhibitors. Apremilast, Tripterygium wilfordii Hook F, and bisphosphonates are other effective treatments.

SAPHO Syndrome and Pustulotic Arthro-Osteitis (PAO)

Synovitis, Acne, Pustulosis, Hyperostosis and Osteitis (SAPHO) syndrome is a rare inflammatory osteo-articular disorder, which encompassed many diseases, including pustulotic arthro-osteitis (PAO). Bone and joint manifestations, including osteitis, synovitis and hyperostosis, are the hallmark of the SAPHO syndrome and affect a variety of regions of the body. Recent GRAPPA survey indicated that more than 80 percent of cases of SAPHO syndrome in Japan were thought to be PAO, originally proposed by Sonozaki et al. in 1981, whereas severe acne was the most commonly reported skin ailment amongst participants with SAPHO syndrome in Israel. SAPHO syndrome is a rare disease and adequate data regarding its prevalence remains unavailable, whereas prevalence of PPP was reported to be 0.12 % in Japan and 10-30% of patients with PPP had PAO. SAPHO syndrome and PAO are predominantly found in patients in the third through fifth decades of life, and a female predominance are seen in both groups. The diagnosis of SAPHO syndrome/PAO is typically made by a rheumatologist or dermatologist. Identification of a variety of the clinical, radiological, and laboratory features outlined, as well as diagnostic criteria, are used to make the diagnosis. Goals for treating patients with SAPHO syndrome/PAO seek to maximize health-related quality of life by improving skin and articular symptoms, preventing structural changes and destruction, and normalizing physical function and social participation. Finally, we review the non-pharmacological (ie: smoking cessation and controlling focal infections) and pharmacological managements including NSAIDs, bisphosphonates, cs DMARDs, bDMARDs, and other treatments for SAPHO syndrome/PAO.

Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome of femoral neoplasm-like onset: a case-based review

Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome is an umbrella term covering a constellation of bone lesions and skin manifestations, but has rarely been clarified in the clinic. We report a 28-year-old woman who had initial onset of SAPHO syndrome with involvement of the femur, and she experienced a tortuous diagnostic course. We also performed a literature review of SAPHO syndrome cases involving the femur and summarize several empirical conclusions by integrating previous findings with our case. Furthermore, we propose our perspective that ailment of the skin caused by infection of pathogens might be the first hit for triggering or perpetuating the activation of the immune system. As a result, musculoskeletal manifestations are probably the second hit by crosstalk of an autoimmune reaction. The skin manifestations preceding bone lesions can be well explained. Current interventions for SAPHO syndrome remain controversial, but drugs aiming at symptom relief could serve as the first preference for treatment. An accurate diagnosis and appropriate treatment can cure patients in a timely manner. Although the pathogenesis of SAPHO syndrome remains to be determined, physicians and surgeons still need to heighten awareness of this entity to avoid invasive procedures, such as frequent biopsies or nonessential ostectomy.

Dr. Li et al reply

We appreciate Wang et al¹ for their interest in our article² and for highlighting the pathogenic role of cytokine dysregulation in SAPHO (synovitis, acne, pustulosis, hyperostosis, and osteitis) syndrome. The authors also address the possible mechanism of secukinumab in the treatment of SAPHO syndrome: blocking the expression of Th17 cell-related cytokines.

Comparing children and adults with chronic nonbacterial osteomyelitis

PURPOSE OF REVIEW

To describe the main clinical differences of children and adults with chronic nonbacterial osteomyelitis (CNO).

RECENT FINDINGS

CNO is a severe systemic autoinflammatory syndrome characterized by multiple bone lesions because of inflammatory osteitis. Delay to diagnosis of CNO can lead to functional impairment, fractures, and chronic pain. Key clinical aspects and disease patterns differ in children and adults, including onset and time to diagnosis, symptom localization, associated comorbidities (i.e. skin, joints), bone lesion distribution pattern, and treatment approach. Novel biomarkers, such as urine N-terminal telopeptide in children and serum IgG4 in adults, are being studied for possible future use in improving diagnosis and guiding treatment. Despite recent advances in our understanding of CNO, many children and adults have a high disease burden and poor long-term outcomes. Recent findings suggest that adults with CNO tend to have a more chronic disease course and are less likely to achieve remission in follow-up.

SUMMARY

The clinical presentation of CNO differs in children and adults, highlighting the importance of these key features for the accurate diagnosis and early treatment in CNO.

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.

New Insights into Adult and Paediatric Chronic Non-bacterial Osteomyelitis CNO

Purpose of Review

To describe in detail the clinical synopsis and pathophysiology of chronic non-bacterial osteomyelitis and SAPHO syndrome.

Recent Findings

Chronic non-bacterial osteomyelitis (CNO) has been identified as a disease entity for almost 50 years. This inflammatory bone disorder is characterized by osteolytic as well as hyperostotic/osteosclerotic lesions. It is chronic in nature, but it can present with episodic flairs and phases of remission, which have led to the denomination “chronic recurrent osteomyelitis”, with its severe multifocal form “chronic recurrent multifocal osteomyelitis” (CRMO). For almost three decades, an infectious aetiology had been considered, since especially Propionibacterium acnes had been isolated from bone lesions of individual patients. However, this concept has been challenged since long-term antibiotic therapy did not alter the course of disease and modern microbiological techniques (including PCR) failed to confirm bone infection as an underlying cause. Over recent years, a profound dysregulation of cytokine expression profiles has been demonstrated in innate immune cells of CNO patients. A hallmark of monocytes from CNO patients is the failure to produce immune regulatory cytokines interleukin-10 (IL-10) and IL-19, which have been linked with genetic and epigenetic alterations. Subsequently, a significant upregulation of pro-inflammatory, NLRP3 inflammasome-dependent cytokines (IL-1β and TNF-α), has been demonstrated.

Summary

The current knowledge on CNO, the underlying molecular pathophysiology, and modern imaging strategies are summarized; differential diagnoses, treatment options, outcome measures, as well as quality of life studies are discussed.

Rapid induction of clinical remission in SAPHO syndrome using high-dose Tripterygium glycosides: A case report

RATIONALE

Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome is a rare disease without standard treatments. Tripterygium wilfordii hook f (TwHF) is a traditional Chinese herb with anti-inflammatory effect, and 1.0 mg/(kg·d) dose of Tripterygium glycosides has been reported to significantly improve the disease activity of a SAPHO patient in a case report. However, the optimal dose of TwHF is still unclear. Here, we report the first case of SAPHO patient who achieved rapid remission in clinical symptoms after receiving 1.5 mg/(kg·d) dose of Tripterygium glycosides treatment.

PATIENT CONCERNS

A 67-year-old woman noted palmoplantar pustulosis and pain in the anterior chest wall and waist. Bone scintigraphy demonstrated the typical tracer accumulation feature and magnetic resonance images showed bone marrow edema in lumbosacral vertebra.

DIAGNOSES

The diagnosis was made by dermatological and osteoarticular manifestations and classical signs in bone scintigraphy in accordance with the diagnostic criteria proposed in 2012.

INTERVENTIONS

Tripterygium glycosides was given with a primary dose of 1.5 mg/(kg·d) for 1 month and then reduced at a rate of 10 mg every 2 weeks until 1.0 mg/(kg·d) for a long-term maintenance.

OUTCOMES

Fast-induced remission on clinical manifestations was achieved and magnetic resonance imaging abnormality was improved significantly. Additionally, no apparent side effects were observed.

LESSONS

1.5 mg/(kg·d) dose of Tripterygium glycosides seems to have fast-induced remission than 1.0 mg/(kg·d) with reliable safety. Besides, Tripterygium glycosides may also have a pharmacological effect of inhibiting osteolysis and enhancing bone strength.

Synovitis, acne, pustulosis, hyperostosis, and osteitis syndrome: review and update

Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome is a spectrum of heterogeneous diseases characterized by osteoarticular and dermatological manifestations. Osteitis and hyperostosis are core clinical manifestations in SAPHO syndrome, typically affecting multiple areas and possibly progressing to irreversible osteoarticular damage. Most patients with SAPHO have cutaneous involvement, mainly manifested as palmoplantar pustulosis and severe acne. Systemic manifestations are uncommon but occasionally reported. Epidemiological studies suggest the annual prevalence of SAPHO syndrome varies from 0.00144 in 100,000 in Japanese individuals to fewer than 1 in 10,000 in White individuals. The precise etiopathogenesis of SAPHO remains unclear, but it is generally considered an autoinflammatory syndrome that may be related to various etiologies, such as immune dysfunction, infection and genetic predisposition. Owing to the relapsing-remitting disease course, the goal of management is to improve clinical symptoms and prevent disease progression. Various treatments, including nonsteroidal anti-inflammatory drugs, conventional disease-modifying antirheumatic drugs, bisphosphonates, biologics, and antibiotics, are promising options for alleviating the disease.

A retrospective study of bone scintigraphy in the follow-up of patients with synovitis, acne, pustulosis, hyperostosis, and osteitis syndrome: is it useful to repeat bone scintigraphy for disease assessment?

OBJECTIVES

To investigate the value of repeated bone scintigraphy in the follow-up of patients with synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome and to characterize the changing pattern of osteoarticular lesions revealed by bone scintigraphy.

METHOD

Twenty-four patients with SAPHO syndrome who had repetitively undergone bone scintigraphy and tests of inflammatory markers (erythrocyte sedimentation rate (ESR) and/or C-reactive protein (CRP)) were included in this retrospective study. The change in accumulation number was recorded as the difference in the number of accumulation sites between consecutive bone scintigraphy. The visual analog scale (VAS) for pain and medications prescribed were also reviewed. The relationships of the change in accumulation number with medication prescribed and change in ESR or CRP were analyzed.

RESULTS

Twenty-four and 23 patients had follow-up tests of ESR and CRP, from which 30 and 28 follow-up data were obtained, containing the corresponding changes in ESR and CRP, respectively. A decrease in total accumulation number observed by bone scintigraphy was rarely observed, while decreases in ESR, CRP, and VAS were predominant. The accumulation number had significantly increased over time (follow-up with ESR: r = 0.389, p = 0.034; follow-up with CRP: r = 0.438, p = 0.020), in accordance with an "imprinting" pattern, while the inflammatory markers and VAS for pain predominantly decreased. There was no significant association between the change in accumulation number (local/total) and the change in ESR or CRP values (p > 0.05) or medications used for SAPHO (p > 0.05).

CONCLUSIONS

This retrospective cohort study of 24 SAPHO patients demonstrated an "imprinting" pattern on bone scintigraphy, without a correlation to the decrease in inflammatory markers, patient disease assessment, or treatment type. Thus, repeated bone scintigraphy did not contribute an additional clinical value for the follow-up of patients with SAPHO.Key Points• In a cohort of 24 SAPHO patients, repeated bone scintigraphy revealed a continuous increase in tracer accumulation number, indicating an "imprinting" pattern.• The change in tracer accumulation number, defined as the difference in the number of accumulation sites between consecutive bone scintigraphy measurements, was inconsistent with the change in ESR, CRP, or VAS for pain.• The medications prescribed for SAPHO did not seem to contribute to a decrease in accumulation number.• Repeated bone scintigraphy did not seem to be useful for the assessment of disease activity in patients with SAPHO.

Enhanced migration and adhesion of peripheral blood neutrophils from SAPHO patients revealed by RNA-Seq

Background

SAPHO syndrome is a rare disease characterized by inflammatory lesions on skin and bones. Diversified manifestation and inadequate understanding of etiology has limited its diagnosis and treatment. The co-occurrence of other immune-mediated diseases strongly suggests an involvement of autoimmunity in SAPHO syndrome. However, the role of the largest population of circulating immune cells, neutrophils, is still not well explored. In this study, we performed RNA sequencing to profile the mRNA expression of neutrophils purified from peripheral blood of SAPHO patients to identify key genes associated with SAPHO syndrome, trying to find new functional molecules or biomarkers for this rare disease.

Results

A total of 442 differentially expressed genes were identified (p < 0.05, fold change > 2), in which 294 genes were upregulated and 148 genes were downregulated. Five differentially expressed genes of interest were verified by quantitative Real-Time Polymerase Chain Reaction (qRT-PCR), among which S100A12 was upregulated and positively related to high-sensitivity C-reactive protein (hsCRP), while the downregulated gene MYADM was positively related to osteocalcin. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that differentially expressed genes were enriched in “systemic lupus erythematosus” and “ECM-receptor interaction”. Gene ontology (GO) enrichment showed that differentially expressed genes may participate in biological processes such as “cell migration” and “cell adhesion”.

Conclusions

In conclusion, this study provides a first insight into transcriptome characteristics of SAPHO syndrome, indicating an over-active neutrophil recruitment in patients and possibly suggesting molecular candidates for further study on diagnosis and pathology of this disease.

Electronic supplementary material

The online version of this article (10.1186/s13023-019-1169-3) contains supplementary material, which is available to authorized users.