Successful Therapy in Cases Series of Systemic Autoinammatory Disease and Literature Review

Objectives: Systemic autoinammatory disease (SAID) is a rare systemic auto-in ﬂ ammatory and progressive disorders. There have been some reports with various therapies in SAID patients. The objective of this study is to describe the chareatercis of four cases of NAIDs bene ﬁ ting from JAK 1/2 inhibitor baricitinib. Methods: We reported the four cases with SAID including two cases of Blau syndrome, one case of FMF and one case of FCAS3 syndrome. These four different patients were either resistant to currently available therapies or biologics were unaccessible during COVID-19 pandemic. We also conducted a systematic literature review about the current therapies of SAID. Results: Although genetically and phenotypically different, four cases of SAID that were treated with single use baricitinib 4 mg per day achieved improvement over eight weeks. We further identi ﬁ ed 132 manuscripts providing more than 100 cases of SAID. Among these patients, 24 underwent biological treatments and 22 of them recovered. In these 132 manuscripts, 2 underwent JAK 1/3 inhibitor tofacitinib treatment and recovered fully. Conclusions: Case series study on the use of Jak inhibitor agents have yielded positive results in our study. For SAID patients baricitinib may be a better choice compared to injection biological treatments.


Introduction
The term autoin ammatory disease was initially proposed by McDermott  Using state-of-the-art molecular and genetic methodologies like NGS numerous genetic markers, some of which may be of diagnostic value have been identi ed. In SAIDs, digenic variants or combinations of more genetic variants in different genes can be detected and a particular of SAID may be related to the NOD2 genes which is located on 6th chromosome. Recently the prevalence of the common NOD2 Page 3 /12 variants has been well studied and documented in SAID populations. The mutations are likely to be disruptive and pathogenic, resulting in loss of structure or function variants of NOD2. These variants may contribute to heterogeneous phenotypes in an individual, complicating the diagnosis and therapy. These disorders may have overlapping clinical phenotypes and characterized by periodic fever, dermatitis, arthritis and gastrointestinal (GI) and sicca like symptoms and has a genetic association with NOD2 variants.
In this study, we followed up four newly diagnosed cases since last year with clinical manifestations at risk for SAID and extended study of the phenotypic and genotypic features of the cases treated with Jak inhibitors. The clinical and laboratory data were then classi ed according to the presence of NOD2 variants (Table 1).

Methods
We prospectively studied 4 cases of SAID between October 2019 and May 2020 in a cohort of 10 cases.
Tests for different autoimmune disorders, neoplastic conditions and immunode ciencies were negative.
All patients with SAID to date have been Chinese Han ethnicity and while both sexes are affected without gender predominance.
The systematic PubMed search was conducted for the literature and was limited to publications in English between1999 and Dec 2020, when the autoin ammatory disease was rst reported, and the following keywords were applied: "autoin ammatory disease", "Yao syndrome", "systemic autoin ammatory syndrome", "Blau syndrome", "NOD2'', "PLCG2"and "FMF". This research was approved by the Institutional Review Board, Tongji Hospital in Wuhan, according to the Declaration of Helsinki. Informed consent was obtained from all the patients.

Case-1
An 18-year-old girl was referred to Rheumatology Clinic in October 2019 for polyarthralgia and recurrent fevers. When 14 years old she was then noticed episodes of recurring high fever (38.5-40℃) with ulike symptoms (generalized aches and myalgia) and had disease flares once every month and each episode lasted for several days. At the age of 16, she also complained of recurrent abdominal pain. A computed tomography scan of the neck, chest, abdomen, and pelvis did not reveal any other lymphadenopathy. An infectious disease workup was negative. Routine blood tests such as complete blood count, complete metabolic panel were unremarkable, and urinalysis is with unexplained proteinuria (24-Hour Urine Protein 437mg). Further genetic testing was positive and heterozygous for the MEVF NM_00024 3.2:c.2040 C>A (p.Met 680Ile)( Figure 1a)and was diagnosed as FMF. Because of the recurrent febrile episodes, the patient was administered colchicine 1.0 mg for a week then increased to 2.0mg daily but without bene ts at all. The patient then was administered baricitinib 4mg daily with complete resolution of symptoms within three months. She remained afebrile at follow-up six months later.
Case-2 A 17-year-old immunocompetent boy was referred to Rheumatology Clinic in December 2019. He developed mild edema and pain of his wrists, knees, DIP and MCP joints at age of 3 when initially diagnosed with juvenile rheumatoid arthritis. He developed ichthyosis plaques on both cheeks ( Figure   1b). The patient's father passed away due to tra c accident at the age of 40 and denial of any relevant disorders reported by patient's mother. There was no family history of similar conditions. At year of 14 after a routine school visual screening examination, his parent was noti ed that a formal ophthalmologic evaluation was needed. From then, he was con rmed as uveitis (Figure1c) and needed tropicamide drops that act as mydriasis to keep his eye vision. And CBC showed normocytic anemia and serum cytokines pro les normal. Chest imaging, QuantiFERON-TB Gold test and HLA-B27 were within normal limits. Peripheral blood lymphocyte subset panel showed decreased slightly of natural killer cell. The genetic testing identi ed that the young patient carries a heterozygous genotypeNM_02216 2.2:c.1000 C>T (p.Arg334Trp) of compound NOD2 variant which has been detected in sporadic Blau syndrome ( Figure  1d). The diagnosis of Blau Syndrome was provisionally made and blood samples from the patient and his brother and mother were tested for known genetic mutations associated with Blau Syndrome, which turned out negative. The past medications also included adamumab for eight weeks for recurrent arthralgia and denial of corticosteroid. Due to COVID-19 pandemic in Wuhan, he had to stop injection for three months and within 3 months after administration of Baricitinib, uveitis has been in remission with a best-corrected visual acuity (BCVA) of 6/6, N6 in both eyes and arthritis resolved completely.

Case-4
A 23-year-old lady was referred to Rheumatology Clinic in May 2020. She presented with recurrent rash to cold temperatures and intermittent fever for 3 years. She has been suffering from polyarthritis in bilateral knees and ankle joints since the age of 12. Physical examination was remarkable overall rashes ( Figure  1h). Laboratory investigation showed moderate anemia and normal white blood cell count. CT scan showed axillary lymphadenopathy and splenomegaly. IgG=4.32 g/L and B Lymphocyte subsets by ow cytometry was as low as 3.0 % (Table-1). Genetic testing for the periodic fever syndrome genes (MEFV, MVK, TNFRSF1A, NLRP3) was normal. Heterozygous for the PLCG2 sequence variants NM_002661. 5:c.1940A>C (p.Tyr647Ser) (Figure 1i) was con rmed positive by NGS. Then the patient was diagnosed with Familial Cold Autoin ammatory Syndrome 3 (FCAS3) (3). She was initially given cetirizine and prednisone 40 mg per day, and the rash, fever episodes and polyarthritis improved partially. But prednisone could not be tapered below 30 mg daily due to deterioration of symptoms. Subsequently, she started with infliximab for 2 months and was then discontinued because fever got worsened. She remained on baricitinib for 3 months, fever and erythema nodosa accompanied with polyarthritis fully diminished.

Discussion
The clinical disorder of SAID was de ned as episodes of seemingly unprovoked in ammation without high titer autoantibodies or antigen-speci c T cells and mediated predominantly by the cells and molecules of the innate immune system with a signi cant host predisposition(4).
FMF is a most frequently common autosomal recessive monogenic SAID, and the Tel Hashomer criteria is the most widely used criteria for the diagnosis of FMF in adult patients. It includes a set of ten criteria grouped into Major criteria, Minor criteria, and molecular criteria which is associated with muation of MEFV gene (5). MEFV is located on the chromosome 16p 13.3 and encoding the Pyrin protein. The rst case patient underwent several treatments and was refractory to colchicine before beginning a regimen of baricitinib and reaching full disease remission. Tobon rstly reported FMF could be controlled by tofacitinib alone (6)and our study is the rst case of FMF controlled by baricitinib alone. Both drugs target the Janus kinases (JAK) family of tyrosine kinases. One possible mechanism is inhibition of STAT activation, which would indirectly block the pathway in which IL-1β plays a role. More recently, PLCG2 were linked to some clinical phenotypes including PLAID, APLAID, FCAS3 and CVID. The gene was located on the 16th chromosome (16q23.3) encodes phospholipase Cγ2 (PLCG2), a transmembrane signaling enzyme that catalyzes the production of second messenger molecules and propagates downstream signals in several hematopoietic cells (10).
FACS3 is an emerging entity and increasingly recognized as autoinflammatory disease characterized by cutaneous urticaria ,erythema and pruritus in response to cold exposure, arthritis/distal extremity swelling due to the dysfunction of the in ammasome (10). It is one of the cryopyrin associated periodic syndromes caused by mutations in the PLCG2 gene. Affected individuals may have additional immunological defects, including antibody de ciency, decreased number of B cells and increased susceptibility to infection (11).As for the therapy, glucocorticoids or cetirizine may be considered as the rst-line treatment option and interleukin (IL)-1 blocker may be effective for refractory cases. Current therapeutic approach with SAID patients is largely empirical and based on the clinical manifestations of the disease. The TNF-αinhibitor has been proposed to be the rst-line therapy for Blau syndrome in Chinese Han ethnicity people by Li et al. (12) and has also been used for colchicine-resistant FMF patients, especially with articular involvement (13). IL-1 blocker including rilonacept, canakinumab and anakinra are currently not avialbile in Chinese market. Therefore, considering inaccessibility of adequate medical care during the pandemic of COVID-19, the practitioner administered alternative baricitinib monotherapy 4mg/day which has been widely applied in rheumatic disease including rheumatoid arthritis.
Since it is well known that the NOD2 variants in the nucleotide-binding domain region are involved in SAID syndrome (14)and Crohn's disease(15) (16). The Janus kinase (JAK) genetic variants are also associated with Crohn's disease and tofacitinib (JAK 1/3 inhibitor)are being evaluated for therapy targeting immune-mediated Crohn's disease(16). The defective gene in SAID is always mapped to 16 th chromosome locus as shown in the previous 4 cases. In addition, the boosted whole exome displayed that these four patients manifested JAK 2 genotype of polymorphisms (rs10758669) C>A. The genotype has been proved to be related with JAK 2 activation in a Han Chinese population with Behcet's and Crohn's diseases (17). Those patients carrying the C risk allele displayed an increased JAK2 expression and NOD2 induced JAK2 phosphorylation compared with patients with the A allele(18).
Collectively, our aim is to describe a novel and alterative therapy of SAID syndrome with JAK inhibitors. Baricitinib is a small-molecule drug that targets the Janus kinases family of tyrosine kinases. Furthermore, it has been used to treat RA, in ammatory bowel disease and alopecia areata (19).Baricitinib is speci cally selective for JAK1/2 that allows blockage of the entire JAK2-STAT pathway, provoking important downregulation in the expression of some cytokines, such as IL-2, IL-6 and TNF-α, and subsequently exerting important immunosuppressive effects. To the best of our knowledge, this is the rst report of SAID syndrome that has shown favorable response to baricitinib when biologics of anakinra, tocilizumab and TNF-inhibitors were unavailable during Covid-19 pandemic. Considering the JAK2 genotypic variant of rs10758669 our observations also suggest a putative motivation to determine the molecular mechanisms through which baricitinib induces remission in SAID patients. There were no serious adverse events warranting permanent discontinuation.

Conclusion
The study focuses on the autoin ammatory disease which is rare and a newly recognized group of immune disorders. The major clinical symptoms including fever, dermatitis, arthritis, gastrointestinal and sicca like symptoms that not speci c and easily be misdiagnosed as "undifferentiated connective tissue disease". This is the rst report about SAID treated with JAK1/2 inhibitor. So, as a rheumatologist I really hope to share the successful experience with global rheumatologist, physicians and immunologists by your journal that owns most medical professional readers.  a WBC: White blood cells 4-10×10 9 / L) , b ESR:Erytherocyte sedimentation rate 0-20mm/h , c CRP creactive protein 0-10 mg/dl . The level of plasma cytokines (Range: IL-1β 5 pg/ml, IL-6 7 pg/ml, TNF-α 8.1 pg/ml). Analysis for ratio of peripheral lymphocytes. (Range: Total B lymphocyte: 5-18%, Helper T lymphocyte: 27-51%, Cytotoxic T lymphocyte: 15-44%, NK lymphocyte: 7-40%).