Akio Morinobu

The biology of IL-12: coordinating innate and adaptive immune responses

Cytokines play critical roles in regulating all aspects of immune responses, including lymphoid development, homeostasis, differentiation, tolerance and memory. Interleukin (IL)-12 is especially important because its expression during infection regulates innate responses and determines the type and duration of adaptive immune response. IL-12 induces interferon-gamma (IFN-gamma) production by NK, T cells, dendritic cells (DC), and macrophages. IL-12 also promotes the differentiation of naïve CD4+ T cells into T helper 1 (Th1) cells that produce IFN-gamma and aid in cell-mediated immunity. As IL-12 is induced by microbial products and regulates the development of adaptive immune cells, IL-12 plays a central role in coordinating innate and adaptive immunity. IL-12 and the recently identified cytokines, IL-23 and IL-27, define a family of related cytokines that induce IFN-gamma production and promote T cell expansion and proliferation.

Cytokines and transcription factors that regulate T helper cell differentiation: New players and new insights

The differentiation of naive CD4+ T cells into subsets of T helper cells is a pivotal process with major implications for host defense and the pathogenesis of immune-mediated diseases. Though the basic paradigm was discovered more than 15 years ago, new discoveries continue to be made that offer fresh insights into the regulation of this process (1). T helper (TH)1 cells produce interferon (IFN)-γ, promoting cell-mediated immunity and control of intracellular pathogens. We now know that TH1 differentiation is regulated by transcription factors such as T-bet, Stat1, and Stat4, as well as cytokines such as IL-12, IL-23, IL-27, type I IFNs, and IFN-γ. In contrast, TH2 cells produce IL-4, which promotes allergic responses and is important in host defense against helminths. The transcription factors Stat6, GATA-3, c-Maf, NFATs, and the cytokine IL-4 promote TH2 differentiation. These key regulators of TH differentiation are the subject of this review.

Impact of smoking as a risk factor for developing rheumatoid arthritis: A meta-analysis of observational studies

Objectives: To assess whether smoking is a risk factor for developing rheumatoid arthritis (RA). Design: Meta-analysis. Method: Data sources were observational studies that examined the association between smoking history and the risk of developing RA identified through Medline and EMBASE (from 1966 to December 2006), relevant books and a reference search. Two authors independently extracted the following: authors’ names, publication year, sample size, participant characteristics, odds ratios (OR) or relative risks, adjustment factors, study design and area where the study was conducted. Data syntheses were based upon random effects model. Summarised syntheses effects were expressed by OR. Results: Sixteen studies were selected from among 433 articles. For men, summary OR for ever, current and past smokers were 1.89 (95% CI 1.56 to 2.28), 1.87 (1.49 to 2.34) and 1.76 (1.33 to 2.31), respectively. For rheumatoid factor-positive (RF+) RA, summary OR for ever, current and past smokers were 3.02 (2.35 to 3.88), 3.91 (2.78 to 5.50) and 2.46 (1.74 to 3.47), respectively. Summary OR for 20 or more pack-years of smoking was 2.31 (1.55 to 3.41). For women, summary OR for ever, current and past smokers were 1.27 (1.12 to 1.44), 1.31 (1.12 to 1.54) and 1.22 (1.06 to 1.40), respectively. For RF+ RA, summary OR for ever, current and past smokers were 1.34 (0.99 to 1.80), 1.29 (0.94 to 1.77) and 1.21 (0.83 to 1.77). Summary OR for 20 or more pack-years of smoking was 1.75 (1.52 to 2.02). Conclusion: Smoking is a risk factor for RA, especially RF+ RA men and heavy smokers.

Signaling by Type I and II cytokine receptors: ten years after

Discovered during the past ten years, Janus kinases and signal transducers and activators of transcription have emerged as critical elements in cytokine signaling and immunoregulation. Recently, knockout mice for all the members of these families have been generated, with remarkably specific outcomes. Equally exciting is the discovery of a new class of inhibitors, the suppressor of cytokine signaling family. The phenotypes of mice deficient in these molecules are also striking, underscoring the importance of negative regulation in cytokine signaling.

Diagnostic Accuracy of Serum 1,3-β-d-Glucan for Pneumocystis jiroveci Pneumonia, Invasive Candidiasis, and Invasive Aspergillosis: Systematic Review and Meta-Analysis

ABSTRACT Serum 1,3-β-d-glucan (BG) assay may be helpful as a marker for the diagnosis of Pneumocystis jiroveci pneumonia (PJP) and invasive fungal infection (IFI). We conducted a systematic review to assess the diagnostic accuracy of this assay. We searched MEDLINE, Web of Science, Cochrane Collaboration databases, Ichushi-Web, reference lists of retrieved studies, and review articles. Our search included studies of serum BG assay that used (i) positive cytological or direct microscopic examination of sputum or bronchoalveolar lavage fluid for PJP and (ii) European Organization for Research and Treatment of Cancer or similar criteria for IFI as a reference standard and provided data to calculate sensitivity and specificity. Only major fungal infections such as invasive candidiasis and invasive aspergillosis were included in the IFI group. Twelve studies for PJP and 31 studies for IFI were included from January 1966 to November 2010. The pooled sensitivity, specificity, diagnostic odds ratio (DOR), and area under the summary receiver operating characteristic curve (AUC-SROC) for PJP were 96% (95% confidence interval [95% CI], 92% to 98%), 84% (95% CI, 83% to 86%), 102.3 (95% CI, 59.2 to 176.6) and 0.96 (95% CI, 0.94 to 0.99), respectively. No heterogeneity was found. For IFI, the values were 80% (95% CI, 77% to 82%), 82% (95% CI, 81% to 83%), 25.7 (95% CI, 15.0 to 44.1), and 0.88 (95% CI, 0.82 to 0.93). Heterogeneity was significant. The diagnostic accuracy of the BG assay is high for PJP and moderate for IFI. Because the sensitivity for PJP is particularly high, the BG assay can be used as a screening tool for PJP.

STAT4 serine phosphorylation is critical for IL-12-induced IFN-γ production but not for cell proliferation

T helper 1 (TH1) differentiation and IFN-γ production are crucial in cell-mediated immune responses. IL-12 is an important regulator of this process and mediates its effects through signal transducer and activator of transcription 4 (STAT4). IFN-γ production is also regulated by the p38 mitogen-activated kinase pathway, although the mechanisms are ill-defined. We show here that GADD45-β and GADD45-γ can induce STAT4 S721 phosphorylation via the MKK6/p38 pathway. Thus, STAT4 could be a target that accounts for the defects in cell-mediated immunity associated with perturbations in the p38 pathway. To investigate the biological significance of STAT4 S721 phosphorylation, we reconstituted primary spleen cells from STAT4-deficient mice with wild-type and mutated STAT4, by using a retroviral gene transduction. We demonstrated that expression of wild-type STAT4, but not the S721A mutant, restored normal TH1 differentiation and IFN-γ synthesis. The inability of STAT4 S721 to restore IFN-γ production was not caused by decreased IL-12R expression because the STAT4 S721 mutant also failed to restore IFN-γ production in STAT4-deficient IL-12Rβ2 transgenic cells. Importantly, STAT4 S721A-transduced cells showed normal proliferative response to IL-12, illustrating that serine phosphorylation is not required for IL-12-induced proliferation. Additionally, the results imply the existence of STAT4 serine phosphorylation-dependent and -independent target genes. We conclude that phosphorylation of STAT4 on both tyrosine and serine residues is important in promoting normal TH1 differentiation and IFN-γ secretion.

Activated STAT4 Has an Essential Role in Th1 Differentiation and Proliferation That Is Independent of Its Role in the Maintenance of IL-12Rβ2 Chain Expression and Signaling

In this study we demonstrated that CD4+ T cells from STAT4−/− mice exhibit reduced IL-12R expression and poor IL-12R signaling function. This raised the question of whether activated STAT4 participates in Th1 cell development mainly through its effects on IL-12 signaling. In a first approach to this question we determined the capacity of CD4+ T cells from STAT4−/− bearing an IL-12Rβ2 chain transgene (and thus capable of normal IL-12R expression and signaling) to undergo Th1 differentiation when stimulated by Con A and APCs. We found that such cells were still unable to exhibit IL-12-mediated IFN-γ production. In a second approach to this question, we created Th2 cell lines (D10 cells) transfected with STAT4-expressing plasmids with various tyrosine→phenylalanine mutations and CD4+ T cell lines from IL-12β2−/− mice infected with retroviruses expressing similarly STAT4 mutations that nevertheless express surface IL-12Rβ2 chains. We then showed that constructs that were unable to support STAT4 tyrosine phosphorylation (in D10 cells) as a result of mutation were also incapable of supporting IL-12-induced IFN-γ production (in IL-12Rβ2−/− cells). Thus, by two complementary approaches we demonstrated that activated STAT4 has an essential downstream role in Th1 cell differentiation that is independent of its role in the support of IL-12Rβ2 chain signaling. This implies that STAT4 is an essential element in the early events of Th1 differentiation.

Expression and function of histone deacetylases in rheumatoid arthritis synovial fibroblasts.

Objective. To explore the effects of histone deacetylases (HDAC) on rheumatoid arthritis synovial fibroblasts (RA-SF). Methods. The expression of mRNA encoding HDAC1 through HDAC11 in RA-SF and osteoarthritis-SF (OA-SF) was determined using real-time polymerase chain reactions. The functions of HDAC1 and HDAC2 in RA-SF were assessed using small interfering RNA (siRNA) technology. Cell counts and proliferation were examined by MTT assays and BrDU ELISA, respectively, and apoptosis was determined using the TUNEL assay and annexin V staining. Levels of cell cycle-related molecules and matrix metalloproteinases (MMP) were tested by Western blotting and ELISA, respectively. Results. Messenger RNA expression of HDAC1 was significantly higher in RA-SF than in OA-SF. Knockdown of HDAC1 and HDAC2 by siRNA resulted in decreased cell counts and cell proliferation, and increased apoptosis in RA-SF. Expression of p16, p21, and p53 was increased by knockdown of both HDAC1 and HDAC2. On the other hand, knockdown of HDAC1, but not of HDAC2, upregulated tumor necrosis factor-α-induced MMP-1 production by RA-SF. Conclusion. HDAC1 is overexpressed in RA-SF compared to OA-SF. HDAC1 supports cell proliferation and survival of RA-SF, but suppresses MMP-1 production. HDAC2 also plays an important role in cell proliferation and apoptosis of RA-SF. Our study provides useful information to develop new HDAC inhibitors for the treatment of RA.

(-)-Epigallocatechin-3-Gallate Suppresses Osteoclast Differentiation and Ameliorates Experimental Arthritis in Mice

OBJECTIVE To verify the effects of (-)-epigallocatechin-3-gallate (EGCG) on osteoclast differentiation and on experimental arthritis in mice. METHODS Human osteoclasts were differentiated from peripheral blood monocytes. The effects of EGCG were examined by tartrate-resistant acid phosphatase (TRAP) staining, bone resorption assay, Western blotting, and quantitative real-time polymerase chain reaction. Arthritis was induced in mice by injecting a cocktail of monoclonal antibodies against collagen. EGCG (20 microg/gm body weight) was administered intraperitoneally every day from day 0 through the end of the experiments (day 15). The effects of EGCG were determined by assessments of joint swelling, histologic changes, and TRAP staining on day 15. RESULTS EGCG reduced the generation of TRAP-positive multinucleated cells, bone resorption activity, and osteoclast-specific gene expression without affecting cell viability. EGCG down-regulated expression of nuclear factor of activated T cells c1 (NF-ATc1), but not of NF-kappaB, c-Fos, and c-Jun, suggesting that down-regulation of NF-ATc1 is one of the molecular bases of EGCG action. Additionally, EGCG treatment ameliorated clinical symptoms and reduced histologic scores in arthritic mice (P < 0.05). The in vivo effect of EGCG on osteoclast differentiation was not clear in this model, probably because EGCG suppressed the inflammation itself. CONCLUSION EGCG suppressed osteoclast differentiation and ameliorated experimental arthritis in mice over the short term. It remains to be established whether EGCG is useful for the prevention and treatment of osteoporosis and rheumatoid arthritis.

Cancer Incidence in Systemic Sclerosis: Meta‐Analysis of Population‐Based Cohort Studies

OBJECTIVE To examine cancer incidence in patients with systemic sclerosis (SSc) through a meta-analysis of population-based cohort studies. METHODS Five different databases (Medline, Scopus, CINAHL [Cumulative Index to Nursing and Allied Health Literature], Web of Science, and Cochrane Collaboration) were searched for articles published between January 1966 and May 2012; review articles and the reference lists from the articles that resulted from the search were also evaluated. Population-based cohort studies with data relevant to the determination of cancer risk in patients with SSc were included. All articles that met strict inclusion criteria were analyzed for data on population size, time of followup, and observed-to-expected cancer ratios, also known as standardized incidence ratios (SIRs). RESULTS Six articles met criteria and were included in the meta-analysis. The pooled SIR for the incidence of cancer overall was 1.41 (95% confidence interval [95% CI] 1.18-1.68), and significant heterogeneity was observed as a consequence of variability in the participants, outcome, study design, and risk of bias among the studies. Men had a significantly higher pooled SIR (1.85 [95% CI 1.49-2.31]) than women (SIR 1.33 [95% CI 1.18-1.49]) (P < 0.01), and stratification for sex eliminated heterogeneity, which indicates that variability among the studies greatly contributed to differences between the sexes. There were no differences between limited cutaneous SSc and diffuse cutaneous SSc (P = 0.77). Significant increases were observed in the risk of cancer of the lung, liver, hematologic system, and bladder, as well as of non-Hodgkins lymphoma and leukemia. CONCLUSION SSc is associated with an increased risk of cancer, particularly lung, liver, hematologic, and bladder cancers, although absolute risk is relatively low. Men with SSc have a higher risk of developing cancer than women.