The role of cytokines in the pathogenesis of SAPHO syndrome.

SAPHO syndrome is a complex inflammatory disorder affecting the skin and bones, characterized by osteomyelitis, acne, and pustulosis. Cytokines play a pivotal role in the pathogenesis of SAPHO syndrome, especially in inflammatory responses and immune regulation. This article reviews the cytokines involved in the pathogenesis of SAPHO syndrome, such as tumor necrosis factor α (TNF-α), interleukin 1ß (IL-1ß), IL-6, IL-10, and transforming growth factor-ß (TGF-ß), and discusses their potential as intervention points for treatment. These findings elucidate the intricate immune regulatory network of SAPHO syndrome and provide a theoretical foundation for the development of new targeted therapeutic strategies.

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

ABSTRACT: 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 ±â€Š12.0 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.

Tofacitinib for the Treatment of Nail Lesions and Palmoplantar Pustulosis in Synovitis, Acne, Pustulosis, Hyperostosis, and Osteitis Syndrome.

Importance: Nail involvement is common in synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome, which has a strong association with quality of life in patients with SAPHO. Tofacitinib is an oral Janus kinase inhibitor that has been previously shown to be effective for nail psoriasis. Objective: To assess the efficacy and safety of tofacitinib for the treatment of nail involvement in SAPHO syndrome. Interventions: Participants received tofacitinib, 5 mg, twice daily, for 12 weeks. Design, Setting, and Participants: This open-label, single-arm, prospective pilot study included 13 patients with SAPHO syndrome accompanied by nail lesions and active palmoplantar pustulosis who were recruited from Peking Union Medical College Hospital from September 2019 to December 2019. Follow-up was completed in March 2020. Analysis began March 2020. Main Outcomes and Measures: The primary end point was the percentage of the change from baseline in Nail Psoriasis Severity Index scores at week 12. Secondary end points included the percentage of the change from baseline in Palmoplantar Psoriasis Area and Severity Index scores, change from baseline in Visual Analogue Scale scores in global osteoarticular pain, Dermatology Life Quality Index scores, and inflammatory markers. Adverse events were recorded throughout the study. Results: Thirteen female Asian patients (means [SD] age, 39.7 [12.3] years) were included, all of whom completed the study. At week 12, significant improvements were observed in Nail Psoriasis Severity Index scores (median, -67% [interquartile range (IQR), -56% to -77%]; P < .001) and Palmoplantar Psoriasis Area and Severity Index scores (median, -71% [IQR, -58% to -78%]; P < .001). Significant improvement was also noted in Dermatology Life Quality Index scores (median, -12 [IQR, -8.5 to -15]; P < .001) at week 12. A significant decrease in Visual Analogue Scale scores in global osteoarticular pain was observed at week 8 (median, -4 [IQR, 0 to -5]; P = .02) but was not significant at week 12. Inflammatory marker levels were decreased, as indicated by erythrocyte sedimentation rate (median, -8 mm/h [IQR, -4 mm/h to -11 mm/h]; P < .001) and high-sensitivity C-reactive protein levels (median, -1.6 [IQR, -0.3 to -4.1]; P = .01). No severe adverse events were observed. Conclusions and Relevance: In this pilot study, tofacitinib yielded significant remission of nail lesions and palmoplantar psoriasis accompanied by an improvement in quality of life in patients with SAPHO syndrome. Additional follow-up studies to evaluate the long-term efficacy and safety of tofacitinib for nail involvement in SAPHO syndrome are warranted. Trial Registration: Chinese Clinical Trial Registry number: ChiCTR1900025941.

Serum IgG4 elevation in SAPHO syndrome: does it unmask a disease activity marker?

OBJECTIVES: SAPHO syndrome is a rare inflammatory disorder with multiple phenotypes, including synovitis, acne, pustulosis, hyperostosis, and osteitis. IgG4 is a subclass of immunoglobulin G, and the elevation of IgG4 has been found in different autoimmune diseases. In the present study, we explored the clinical significance of serum IgG4 levels in patients with SAPHO syndrome. METHODS: Fifty-two patients who met the classification criteria of SAPHO syndrome were included in this study. Clinical data and disease activity markers were collected including erythrocyte sedimentation rate (ESR), high sensitivity C-reactive protein (hsCRP), pain visual analogue scale (VAS), Bath Ankylosing Spondylitis Metrology Index (BASMI), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI) and Ankylosing Spondylitis Disease Activity Score (ASDAS). Serum immunoglobin (IgA, IgM, and IgG) and IgG subclass (IgG1, IgG2, IgG3, and IgG4) levels were determined using the immunonephelometric assay. RESULTS: Raised serum IgG4 levels (>1400 mg/dL) were detected in 23% (12/52) of patients. Patients with elevated sIgG4 levels had significantly higher pain VAS (5.42±2.76 vs. 3.08±1.78, p=0.02), BASMI (1.80±1.64 vs. 0.38±0.94, p=0.03) and ASDAS (3.20±0.65 vs. 1.74±0.58, p<0.001) levels compared with patients with normal sIgG4 levels. This difference was also observed for ESR (38.2 vs. 22.2 mm/h, p=0.01) and serum CRP (21.0 vs. 2.2 mg/L, p=0.04) levels, which also positively correlated with sIgG4 levels. We also included 4 patients whose IgG4 levels decreased and correlated with the decrease in hsCRP and ESR levels after treatment. CONCLUSIONS: Elevated sIgG4 levels are common in patients with SAPHO syndrome and are associated with high disease activity. Further investigations are needed for this phenomenon.

SAPHO: has the time come for tailored therapy?

SAPHO (synovitis, acne, pustulosis, hyperostosis and osteitis) syndrome is a heterogeneous condition combining osteoarticular and cutaneous manifestations. Conventional treatments are mostly ineffective. We hereby report two patients, the first with an aggressive form of disease and the second with an incomplete response to two different anti-TNF-α agents. Both were successfully treated with tocilizumab and ustekinumab, respectively, over a long period of time. A narrative review of a biological therapy in SAPHO syndrome yielded very little information on the specific use of these agents. We highlight the advantages of personalising therapy and describe emerging promising treatments for this disease.

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.

Reduction of peripheral natural killer cells in patients with SAPHO syndrome.

OBJECTIVES: Little is known about the roles of peripheral immune cell subsets in synovitis, acne, pustulosis, hyperostosis and osteitis (SAPHO) syndrome. Up to now, just a few studies have focused on this issue. We aimed to analyse the distribution and phenotype of T cell subsets and natural killer (NK) cells in the peripheral blood of patients with SAPHO syndrome. METHODS: The proportion and absolute counts of circulating immune cells were assessed in 19 patients diagnosed as SAPHO syndrome and 19 healthy controls. CD4+T cell subsets were also analysed in 9 untreated SAPHO patients and 9 healthy volunteers by flow cytometry. RESULTS: The proportion and absolute counts of NK cells were significantly reduced in SAPHO patients in comparison with the controls (proportion, 10% vs. 18%, p<0.001; absolute counts, 231/µl vs. 307/µl, p=0.014). Conversely, the proportion and absolute counts of Th17 cells in untreated SAPHO patients were significantly higher than that in the healthy controls (proportion, 1.49% vs. 0.93%, p=0.004; absolute counts, 14.36/µl vs. 5.14/µl, p<0.001). Similarly, Th17/Th1 cells were significantly increased (proportion, 0.45% vs. 0.33%, p=0.024; absolute number, 5.47/µl vs. 1.98/µl, p<0.001), but there was no significant difference between the percentage and number of Treg cells in patients with SAPHO syndrome and healthy controls. Thus, the ratio of Th17/Treg was increased in SAPHO patients (0.68 vs. 0.17, p=0.004). CONCLUSIONS: Our data suggested that the immune inflammation in SAPHO patients may be related to the depletion of NK cells and the imbalance of Th17 and Treg cells. A reduction of peripheral NK cells may exacerbate the disease progression by not being inhibited Th17 cells.

Pyoderma gangrenosum and its syndromic forms: evidence for a link with autoinflammation.

Pyoderma gangrenosum is a rare inflammatory neutrophilic dermatosis manifesting as painful ulcers with violaceous, undermined borders on the lower extremities. It may occur in the context of classic syndromes like PAPA (pyogenic arthritis, pyoderma gangrenosum and acne) and SAPHO (synovitis, acne, pustulosis, hyperostosis, osteitis), as well as in a recently described entity named PASH (pyoderma gangrenosum, acne and suppurative hidradenitis). Pyoderma gangrenosum has recently been included within the spectrum of autoinflammatory diseases, which are characterized by recurrent episodes of sterile inflammation, without circulating autoantibodies and autoreactive T cells. In PAPA syndrome, different mutations involving the PSTPIP1 gene, via an increased binding affinity to pyrin, induce the assembly of inflammasomes. These are molecular platforms involved in the activation of caspase 1, a protease that cleaves inactive prointerleukin (pro-IL)-1ß to its active isoform IL-1ß. The overproduction of IL-1ß triggers the release of a number of proinflammatory cytokines and chemokines, which are responsible for the recruitment and activation of neutrophils, leading to neutrophil-mediated inflammation. In SAPHO syndrome, the activation of the PSTPIP2 inflammasome has been suggested to play a role in inducing the dysfunction of the innate immune system. Patients with PASH have recently been reported to present alterations of genes involved in well-known autoinflammatory diseases, such as PSTPIP1, MEFV, NOD2 and NLRP3. Pyoderma gangrenosum and its syndromic forms can be regarded as a single clinicopathological spectrum in the context of autoinflammation.

Biological treatments for SAPHO syndrome: an update.

Synovitis, Acne, Pustulosis, Hyperostosis and Osteitis (SAPHO) syndrome is a rare and often unrecognized disease with prominent inflammatory cutaneous and articular manifestations. Since the identification of the syndrome many immunosuppressive drugs have been used for the management of SAPHO, with variable results. The use of anti- TNF-α agents as a therapeutic option for SAPHO cases unresponsive or refractory to conventional drugs, demonstrated their efficacy for bone, skin and joints manifestations. TNF-α is a pro-inflammatory cytokine and pivotal regulator of other cytokines, including IL-1 ß , IL-6 and IL-8, involved in inflammation, acute-phase response induction and chemotaxis. IL-1 inhibition strategies with Anakinra have proven their efficacy as first and second line treatment. We herein review the literature concerning the use of biological drugs in patients with SAPHO syndrome. In addition, we describe for the first time the use of Ustekinumab, an antibody against the p40 subunit of IL-12 and IL-23, after failure of multiple drugs including anti-TNF-α and Anakinra. This anti-IL12/IL23 agent could be a promising therapeutic option, also considering the opportunity to interfere with the IL23/TH17 pathway, which we recently found disturbed. Furthermore, a rationale emerges for the use of the new anti-IL-1 antagonists or the IL-17 blockade, in particular for the most difficult-to-treat SAPHO cases.

TH17 cells are increased in the peripheral blood of patients with SAPHO syndrome.

To assess whether the immune derangement previously observed in SAPHO syndrome could be linked to variations in blood TH1, TH2 or TH17 lymphocytes frequency. Seven SAPHO patients with a protracted course of the disease were studied ex-vivo for intracellular cytokines production by means of flow-cytometry and compared with matched groups of Psoriatic Arthritis patients and healthy controls. The Kruskal-Wallis test on the median of the three categories showed that there is a significant association between the TH17 levels and the category (p value = 0.02474). The mean and variance for the proportion of IL-17 producing CD4+ cells were compared between groups showing significant differences between SAPHO versus PsA subgroup (p = 0.05) and SAPHO versus healthy controls (p = 0.008). Interestingly, activation of TH17 axis, but not of TH1 and TH2, has been found, and can be observed both in patients with different activity of the disease or treated with different drugs. The TH17 increase in peripheral blood of our SAPHO subjects resembles the one recently found in patients with different AIDs. Novel therapeutic options in these patients may therefore include IL-17 blockade.

The inflammasomes in autoinflammatory diseases with skin involvement.

During the past years, significant progress in the understanding of the complexity, regulation, and relevance of innate immune responses underlying several inflammatory conditions with neutrophilic skin involvement has been made. These diseases belong to the novel class of autoinflammatory diseases, and several are caused by mutations in genes regulating the function of innate immune complexes, termed inflammasomes, leading to enhanced secretion of the proinflammatory cytokine IL-1ß. Consequently, targeting of IL-1ß has proven successful in the treatment of these diseases, and the identification of related pathogenic mechanisms in other more common skin diseases characterized by autoinflammation and neutrophilic tissue damage also provides extended opportunities for therapy by interfering with IL-1 signaling.

Autoinflammatory bone diseases.

Autoinflammatory bone disease is a new branch of autoinflammatory diseases caused by seemingly unprovoked activation of the innate immune system leading to an osseous inflammatory process. The inflammatory bone lesions in these disorders are characterized by chronic inflammation that is typically culture negative with no demonstrable organism on histopathology. The most common autoinflammatory bone diseases in childhood include chronic nonbacterial osteomyelitis (CNO), synovitis, acne, pustulosis, hyperostosis, osteitis syndrome, Majeed syndrome, deficiency of interleukin-1 receptor antagonist, and cherubism. In this article, the authors focus on CNO and summarize the distinct genetic autoinflammatory bone syndromes.

Life-threatening disseminated tuberculosis as a complication of TNF-α blockade in an adolescent.

Life-threatening disseminated tuberculosis developed in a 17-year-old girl who was treated with the TNF-α blocker adalimumab for refractory SAPHO syndrome. The patient presented to the emergency department with dyspnea and somnolence and within 2 h developed the clinical picture of a septic shock. In addition to this unusual presentation, she showed a complicated course with increasing cerebral granuloma formation in spite of adequate antimycobacterial treatment. Immune reconstitution after discontinuation of TNF blockade may contribute to this "paradoxical reaction." Possible implications for screening, diagnosis, and treatment of tuberculosis in children and adolescents receiving anti-TNF treatment are discussed.

Prevalence of autoantibodies in SAPHO syndrome: a single-center study of 90 patients.

OBJECTIVE: To determine the prevalence of the most often tested autoantibodies in synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome. METHODS: We identified 90 patients seen in our unit between June 2002 and June 2009, and diagnosed according to the proposed criteria for SAPHO syndrome. Demographic and clinical data were collected as well as immunological results, including antinuclear, antithyroid peroxydase (TPO), antithyroid globulin (Tg), antigastric parietal cell, antismooth muscle, antimitochondria, and anti-liver-kidney microsome (LKM) antibodies. Anticyclic citrullinated peptide (CCP) antibodies were analyzed in 69 patients, antibodies to soluble extractable nuclear antigens in 43, anti-double-stranded DNA (dsDNA) antibodies in 22 [depending on the type of fluorescence of antinuclear antibody (ANA)], and antiendomysium antibodies in 55. RESULTS: Autoantibodies were found in 20 patients (22.2%): 14 patients (15.5%) had positive ANA (titer >/= 1/160); among them, 10 (11%) patients never took a lupus-inducing drug. Antithyroid antibodies (anti-TPO and/or anti-Tg antibodies) were found in only 3 patients (3.3%). Three patients (3.3%) were positive for antigastric parietal cell antibodies and 4 (4.4%) were weakly positive for antismooth muscle antibodies. Antimitochondria and LKM antibodies were negative in all 90 patients. Anti-CCP and anti-dsDNA antibodies were negative in the 69 and 22 patients tested, respectively. One out of 43 patients (2.3%) had anti-SSA antibodies. Antiendomysium antibodies were negative in the 55 patients tested. CONCLUSION: Our study indicates an increased prevalence of autoantibodies in SAPHO syndrome, with no specific profile. We failed to confirm the reports of an increased prevalence of antithyroid antibodies. These results tend to support a link between autoimmunity and SAPHO syndrome.

SAPHO syndrome: is a range of pathogen-associated rheumatic diseases extended?

SAPHO syndrome, representing a constellation of synovitis, acne, palmo-plantar pustulosis, hyperostosis, and osteitis, is now recognized as a distinct medical entity: a reactive infectious osteitis. Genetic, immunological, and bacterial mechanisms are implicated in the development of the disease. Diagnostic problems may arise due to non-complete manifestations of SAPHO: either acne and arthritis or acne and anterior wall osteitis with an unclear pustulosis history. The interventional study of Assmann et al. is a significant addition to a long range of publications showing an association of SAPHO with Propionibacterium acnes. Randomized control studies are needed to confirm the effects of antibiotic therapy.

Characterization of the immune response in the synovitis, acne, pustulosis, hyperostosis, osteitis (SAPHO) syndrome.

OBJECTIVE: The aetiology of SAPHO (synovitis, acne, palmoplantar pustulosis, hyperostosis, osteitis) syndrome seems to involve genetic, infectious and immunological components. We examined innate and adaptive immune responses in SAPHO syndrome, as compared with PsA and RA. We also studied the effect of etanercept on immunological parameters. METHODS: We studied 29 patients with SAPHO syndrome, as well as 22 patients with RA, 21 patients with PsA and 15 healthy controls. Adaptive immune responses were investigated by assaying total serum immunoglobulins and several autoantibodies. Innate immunity was studied by quantifying blood PMN functions and plasma cytokine levels. PMN responses to Propionibacterium acnes were tested ex vivo. Eight patients who received etanercept for refractory rheumatic disorders were tested before and after 28 days of treatment. RESULTS: SAPHO syndrome was associated with elevated IL-8 and IL-18 plasma levels. IL-8 and TNF-alpha production by purified PMN was higher in the three patient groups than in the healthy controls, but the oxidative burst and IL-18 production were normal. No autoantibodies were detected in SAPHO patients. Induction of PMN IL-8 and TNF-alpha production by P. acnes was impaired in the SAPHO group as compared with the RA and PsA groups. After 28 days of etanercept therapy, PMN IL-8 and TNF-alpha production was down-regulated and TNF-alpha plasma levels were increased. CONCLUSIONS: These results support the view that the SAPHO syndrome may be triggered by an infectious state involving P. acnes, contributing to the strong humoral and cellular pro-inflammatory responses. Etanercept modulation of PMN activation status emphasizes these new immunological findings.

SAPHO osteomyelitis and sarcoid dermatitis in a patient with DiGeorge syndrome.

We report the development and spontaneous resolution of annular erythematous skin lesions consistent with sarcoid dermatitis in a child with DiGeorge syndrome (DGS) carrying the 22q11.2 microdeletion. The skin lesion developed after she was treated with isoniazid (INH) following exposure to active tuberculosis (TB). After resolution of the skin lesions, this child developed sterile hyperplastic osteomyelitis consistent with SAPHO (synovitis, acne, pustulosis, hyperostosis, and osteitis) osteomyelitis in her right mandible triggered by an odontogenic infection. This child had congenital heart disease, dysmorphic facies, recurrent sinopulmonary infection, gastroesophageal reflux disease, scoliosis, reactive periostitis, and developmental delay. She had a low CD4 and CD8 T cell count with a normal 4/8 ratio, but normal cell proliferation and T cell cytokine production in response to mitogens. When she was presented with sterile osteomyelitis of right mandible, she revealed polyclonal hypergammaglobulinemia with elevated erythrocyte sedimentation rate (ESR)/angiotensin converting enzyme (ACE) levels, but negative CRP. Autoimmune and sarcoidosis workup was negative. Inflammatory parameters gradually normalized following resolution of odontogenic infection and with the use of non-steroidal anti-inflammatory drugs (NSAIDs). The broad clinical spectrum of DGS is further expanded with the development of autoimmune and inflammatory complications later in life. This case suggests that patients with the DGS can present with unusual sterile inflammatory lesions triggered by environmental factors, further broadening the clinical spectrum of this syndrome.