Japanese Journal of Clinical Immunology Vol. 40(2017) No. 3

  Some patients with idiopathic interstitial pneumonias (IIPs) have clinical features that suggest autoimmune process but not fulfill established criteria for connective tissue disease (CTD). Different terms and criteria have been proposed to describe these patients, which includes undifferentiated connective tissue disease (UCTD), lung dominant connective tissue disease (LD-CTD), and autoimmune-featured interstitial lung disease (AIF-ILD). To marshal these ununiform classification criteria, the “European Respiratory Society/American Thoracic Society Task Force on Undifferentiated Forms of Connective Tissue Disease-associated Interstitial Lung Disease” proposed a consensus regarding the nomenclature and classification criteria for patients with IIP and features of autoimmunity with the term “interstitial pneumonia with autoimmune features” (IPAF). It was reported that patients with IPAF accounted for 7.3%∼34.1% of patients with interstitial lung disease (ILD). Survival, rate of progressing to CTD, appropriate treatment, and treatment response are not yet elucidated. Furthermore, it is not determined whether IPAF is a distinct category of ILD or simply a part of IIP. These questions should be elucidated by future prospective cohort studies. Hopefully, rheumatologists should participate in not only clinical trials but also in multidisciplinary discussions for IPAF.

  Severe combined immunodeficiency (SCID) is impaired in lymphocyte development and function. Affected children have extreme susceptibility to infections, which are fatal in the first year of life without treatment. The estimate of incidence is one in approximately 50,000 live birth. The first series of diseases were described in 1950s, and all patients died in infancy. The first transplant for SCID was carried out in 1968, and it has been described that SCID patients could be treated by hematopoietic stem cell transplantation (HSCT) since then. Adenosine deaminase and common gamma chain were identified to be causative genes for SCID in 1972 and 1993, respectively. SCID arises from a variety of genetic defects. The early intervention of healthy SCID infants without infections affords higher survival rate, and newborn screening (NBS) was suggested. T-cell receptor (TCR) exicision circles (TRECs) are circular DNA formed from the leftover fragment generated from the TCR rearrangement. TRECs can be measured from a small aliquot of DNA such as Guthrie card by quantitative PCR. SCID patients lack TRECs, and TRECs quantification is useful for NBS for SCID. NBS for SCID have been already carried out in most of the Unite States, and the early introduction is desired in Japan to save SCID children.

  Leptin is secreted from adipocytes and acts mainly on the hypothalamus causing weight loss due to suppression of appetite and increased energy expenditure. On the other hand, the leptin receptor is also expressed in hematopoietic cells and its action on the immune system has become known, and the significance of leptin in autoimmune diseases has gradually become clear. It has been shown that leptin acts as an exacerbating factor in many autoimmune diseases and it is suggested that inhibition of leptin signal may be a novel therapeutic method for autoimmune diseases. In this article, we will outline the significance of leptin in the immune system based on the current reports.

  Central nervous system (CNS), which is made up of brain and spinal cord, is protected from the invasion of harmful agents, such as various pathogens, chemical products or immune cells by a special structure “Blood Brain Barrier (BBB)”. BBB highly preserves the homeostasis of CNS environment. On the other hand, there are many diseases in CNS regions which is associated with infection or autoimmunity, that means there may exist the “gateway” for pathogens or immune cells to attack CNS. Until recently, the molecular mechanism of the gateway formation has not been elucidated. Through studies in the multiple sclerosis model experimental autoimmune encephalomyelitis, we have clarified the mechanism of the gateway formation, and also the locations of gateways which depend on the regional neural activation. Further more, we have also discovered a massive chemokine-inducing mechanism “inflammation amplifier” via co-activation of NF-κB pathway and STAT3 pathway. It is essential for the development of inflammation in various diseases and is a molecular basis of BBB breakdown.

  Deficiency of interleukin thirty-six receptor antagonist (DITRA) and CARD14 mediated psoriasis (CAMPS) are autoinflammatory diseases in dermatology. The causative genes of DITRA and CMAPS have been identified recently. In this paper, IL36RN and CARD14, the causative gene for DITRA and CAMPS, respectively were explained. In addition, clinical features and therapies for generalized pustular psoriasis not associated with psoriasis vulgaris (GPP without PsV), and pityriasis rubra pilaris type V (PRP type V) were described. GPP without PsV and PRP type V are representative diseases of DITRA and CAMPS, respectively.

  Methotrexate-associated lymphproliferative disorder (MTX-LPD) is a rare but critical complication developing in patients treated with methotrexate. Now that methotrexate is an anchor drug in the management of rheumatoid arthritis and become commonly used, MTX-LPD cases have increased. Many things has been unclear such as incidence, demographic characters, and risk factors. However, as the researches increased, several interesting topics has been demonstrated like associations with Epsteiin-Barr virus and with cell-mediated immunity. This report reviews newly the latest findings and future challenges on MTX-LPD.

  Mutations in the RAG1/RAG2 genes are associated with a broad spectrum of clinical phenotypes, ranging from severe combined immunodeficiency to various autoimmune diseases. The diversity of the clinical symptoms is determined not only by the residual RAG recombinase enzyme activity as determined by the mutations, but also by multiple environmental factors and, in rare cases, by second site mutations within the RAG1/RAG2 genes. The residual recombinase activity is responsible for the oligoclonal expansion of autoreactive T cells. Omenn syndrome is the result of intense Th2 type inflammation involving the skin and multiple other organs triggered by these T cells. In this review, the molecular pathology of diseases caused by RAG1/RAG2 mutations, in particular Omenn syndrome, will be discussed. Furthermore, abnormalities in other molecules involved in V(D)J recombination will be discussed in relation to Omenn-like syndrome.

  Kawasaki disease (KD) is a systemic vasculitis in infants. In KD, encephalopathy is rarely (0.1%) associated, however, clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) has previously been reported in some pediatric patients. Here, we report on a 2-year-old girl who had KD complicated with MERS. The patient experienced generalized clonic convulsion and prolonged consciousness disturbance with fever for 2 days. Her head MRI showed a high signal intensity lesion in the splenium of the corpus callosum in diffusion-weighted images, and low apparent diffusion coefficient (ADC) values on day 3. An electroencephalogram showed high voltage slow waves on the occipital and parietal head. On the same day, it was confirmed that the patient showed all the main symptoms of KD. Based on these findings, we diagnosed her with MERS-complicated KD. Even though she was treated with immunoglobulin (total 4 g/kg) and pulsed-dose methylprednisolone, her fever and consciousness disturbance continued, and blood tests showed that inflammation markers remained high. We then treated the patient with infliximab on day 9, and within a few hours of the treatment her fever dropped and all symptoms of KD and consciousness disturbance disappeared. No recurrence of KD or other complications of KD occurred, and she was discharged on day 23. We propose that infliximab is an effective optional treatment for immunoglobulin/glucocorticoid-resistant KD with MERS. To clarify this possibility, further case accumulation is warranted.

  Objective: To evaluate the safety and effectiveness of certolizumab pegol (CZP) in a real-world setting among Japanese patients with rheumatoid arthritis. Methods: Post-marketing surveillance data from 2,579 patients treated with CZP were analyzed. Adverse events (AEs) observed during the 24-week CZP treatment period were recorded. Disease activity was evaluated using DAS28-ESR and DAS28-CRP at baseline, Week 12, Week 24, or at withdrawal. Results: The total period of exposure to CZP was 1313.8 patient-years (PY). AEs were reported in 658 (25.5%) patients, at an event rate (ER) of 73.68/100 PY. The most frequent serious AEs were pneumonia, herpes zoster, and interstitial lung disease, at ER per 100 PY of 2.06, 1.29, and 1.22, respectively. Mean disease activity scores at baseline, as measured by DAS28-ESR and DAS28-CRP, were 4.77 ± 1.34 and 4.21 ± 1.27, respectively. Mean changes from baseline at the last observation were −1.29 ± 1.46 and −1.30 ± 1.42, respectively. EULAR good or moderate responses were achieved in 65% of patients. Longer disease duration, prior biologics use, and treatment without MTX co-therapy were associated with EULAR no response. Conclusion: In this interim analysis, no new safety signals were observed. Clinical response to CZP was observed in approximately two thirds of patients.

  IgG4-related disease (IgG4-RD) is a chronic inflammatory disease characterized by tumescent lesions with characteristic storiform fibrosis, obliterative phlebitis and a marked lymphoplasmacytic infiltrate that includes a large number of IgG4 positive plasma cells. It's widely accepted that rituximab-mediated B cell depletion therapy is effective for this disease. Important mechanistic insights correlated with the pathogenesis of IgG4-RD have been gradually disclosed from studies of patients treated by B cell depletion. 1) IgG4-RD patients have the large clonal expansion of activated plasmablasts and CD4⁺CTLs, so this disease might be antigen-driven. 2) CD4⁺CTLs are the dominant population in affected tissues, on the other hands direct examination of T_H1 and T_H2 cells in tissues reveal that these subsets are sparse. 3) CD4⁺CTLs into affected lesions secret cytotoxic, inflammatory, and pro-fibrotic cytokines, indicating reactivation by antigen in tissue sites. 4) The decline in CD4⁺CTLs number by B cell depletion is associated with clinical remission of IgG4-RD patients. 5) CD4⁺CXCR5⁺T_FH cells that express IL-4 are located outside germinal centers and specialized T_FH cells that expanded dramatically in conditions with polarized class switching to IgG4. These results suggested that the disease pathogenesis might be based on orchestrating of activated plasmablasts, CD4⁺CTLs, and T_FH cells.