Understanding mental toughness at a Women's Australian rules football club.

Scholars have argued that mental toughness is a term that represents hypermasculine ideals. This hypermasculinity ideal could be considered relevant in the sport of Australian rules football, which has been played, at the professional level, by male athletes for the majority of its existence. Given the rising popularity of the Australian Football League Women's (AFLW), the present research sought to explore how the term mental toughness was understood at an AFLW club through a cultural sport psychology lens. Interviews were conducted with players (n = 4) and coaches (n = 6) from an AFLW club over the course of a competitive season. Data were transcribed verbatim and thematically analysed, with themes constructed to correspond with different levels of contextual influence. From this analysis, the club values and underlying assumptions, the social truths, and the role models/archetypes that provided a collective understanding of the term were identified. Mental toughness was defined by high-performance values of the men's game, which had implications for female athletes in this environment who are not afforded the same opportunities to fully embody these values. Mental toughness is positioned, in this environment, as an ideal with different meanings for female athletes due to structural factors associated with elite-level competition (e.g., full-time versus part-time professionalism).

The Perceptions of Elite Professional Rugby League Players and Staff on the National Rugby League Annual Calendar: A Mixed-Methods Study.

BACKGROUND: In recent years, the length of elite sporting competitions has raised concerns regarding player well-being, highlighting a need to review current match calendars. Therefore, this study aimed to explore the perceptions of elite National Rugby League (NRL) players and staff on the annual training and competition calendar from a player workload and well-being perspective. METHODS: This study adopted a mixed-methods approach, using a sequential explanatory design. Phase one implemented a cross-sectional survey, and phase two utilised semi-structured interviews. Four hundred and thirty-nine elite rugby league players and 46 staff completed the survey. Eighteen elite professional NRL players and six football staff were interviewed, and verbal data were analysed into pre-defined topic summaries using qualitative coding reliability methods. Topics included in-season, off-season, pre-season and well-being. RESULTS: Data analysis suggests that elite NRL players and staff believe players appear particularly comfortable with the current number of games; however, they are at their maximum capacity. Importantly, this study identified several minority groups that may require support to enhance player well-being. Players believe reducing the pre-season would negate fatigue experienced later in the subsequent season. Players and staff believe this timeframe still provides sufficient time to prepare for the upcoming season. Further, players were open to extending the off-season to 8-10 weeks and believed that extra time would allow for greater recovery from the previous season. Mid-season congested scheduling affects players following the intensified period and requires attention to alleviate fatigue. CONCLUSION: The results of this study convey important implications for the NRL, emphasising a need to review their annual training and competitive calendar, or to implement specific strategies to enhance the well-being of minority groups. The findings from this study should be considered when discussing the ideal length and structure of the match calendar to support players' physical and mental welfare.

Competitive Situations Requiring Mental Toughness in Women's Australian Rules Football.

In the last decade, mental toughness (MT) researchers have been interested in the behaviours exemplifying MT. Despite this interest, little attention has been paid to the competitive situations these behaviours occur in. Hence, the aim of the current study was to start addressing this gap by comprehensively focusing on the situations requiring MT in sport - specifically, the contextual demands linked to MT in women's Australian rules football. Focus groups and individual semi-structured interviews were conducted at two Australian rules football clubs after each competitive round of the 2020 season. Following analysis of participant responses, three broad situational categories were created, representing the psychological demands required by the player or team to successfully overcome in-game challenges. These categories were: context intelligence, attentional regulation, and emotional regulation. This study identified that situations requiring MT also required a degree of acceptance and commitment - alluding to a potential link between acceptance-commitment therapy (ACT) and MT. Conceptually, this view offers a new perspective on the psychological process of being mentally tough in competition. The link between ACT and MT also offers an avenue for MT development. Recommendations are made for incorporating these identified situations into regular training sessions following affective learning design principles.

Contribution of a European-Prevalent Variant near CD83 and an East Asian-Prevalent Variant near IL17RB to Herpes Zoster Risk in Tofacitinib Treatment: Results of Genome-Wide Association Study Meta-Analyses.

OBJECTIVE: Tofacitinib is an oral JAK inhibitor for the treatment of rheumatoid arthritis (RA), psoriatic arthritis, and ulcerative colitis, and has been previously investigated for psoriasis (PsO). This meta-analysis of genome-wide association studies (GWAS) was performed to identify genetic factors associated with increased risk/faster onset of herpes zoster (HZ) in subjects with RA or PsO receiving tofacitinib treatment, and to determine potential mechanisms that could be attributed to the varying rates of HZ across ethnicities. METHODS: In an ethnicity/indication-specific, trans-ethnic, trans-population meta-analysis of GWAS in subjects with RA or PsO from phase II, phase III, and long-term extension studies of tofacitinib, 8 million genetic variants were evaluated for their potential association with time to an HZ event and incidence of an HZ event (case versus control) with tofacitinib treatment, using Cox proportional hazard and logistic regression analyses, respectively. RESULTS: In total, 5,246 subjects were included (3,168 with RA and 2,078 with PsO). After adjustment for age, baseline absolute lymphocyte count, genetically defined ethnicity, and concomitant methotrexate use (in RA subjects only), 4 loci were significantly associated with faster onset of HZ in European subjects (P < 5 × 10-8 ), including a single-nucleotide polymorphism (SNP) near CD83 (frequency of risk allele ~2% in European subjects versus ~0.1% in East Asian subjects). In the trans-ethnic, trans-population meta-analysis, the CD83 SNP remained significant. Four additional significant loci were identified in the meta-analysis, among which a SNP near IL17RB was associated with faster onset of HZ (meta-analysis hazard ratio 3.6 [95% confidence interval 2.40-5.44], P = 7.6 × 10-10 ; frequency of risk allele ~12% in East Asian subjects versus <0.2% in European subjects). CONCLUSION: Genetic analysis of tofacitinib-treated subjects with RA or PsO identified multiple loci associated with increased HZ risk. Prevalent variants near the immune-relevant genes CD83 and IL17RB in European and East Asian populations, respectively, may contribute to risk of HZ in tofacitinib-treated subjects.

Discovery of Tyrosine Kinase 2 (TYK2) Inhibitor (PF-06826647) for the Treatment of Autoimmune Diseases.

Tyrosine kinase 2 (TYK2) is a member of the JAK kinase family that regulates signal transduction downstream of receptors for the IL-23/IL-12 pathways and type I interferon family, where it pairs with JAK2 or JAK1, respectively. On the basis of human genetic and emerging clinical data, a selective TYK2 inhibitor provides an opportunity to treat autoimmune diseases delivering a potentially differentiated clinical profile compared to currently approved JAK inhibitors. The discovery of an ATP-competitive pyrazolopyrazinyl series of TYK2 inhibitors was accomplished through computational and structurally enabled design starting from a known kinase hinge binding motif. With understanding of PK/PD relationships, a target profile balancing TYK2 potency and selectivity over off-target JAK2 was established. Lead optimization involved modulating potency, selectivity, and ADME properties which led to the identification of the clinical candidate PF-06826647 (22).

Demonstration of In Vitro to In Vivo Translation of a TYK2 Inhibitor That Shows Cross Species Potency Differences.

Translation of modulation of drug target activity to therapeutic effect is a critical aspect for all drug discovery programs. In this work we describe the profiling of a non-receptor tyrosine-protein kinase (TYK2) inhibitor which shows a functionally relevant potency shift between human and preclinical species (e.g. murine, dog, macaque) in both biochemical and cellular assays. Comparison of the structure and sequence homology of TYK2 between human and preclinical species within the ATP binding site highlights a single amino acid (I960 → V) responsible for the potency shift. Through TYK2 kinase domain mutants and a TYK2 980I knock-in mouse model, we demonstrate that this single amino acid change drives a functionally relevant potency difference that exists between human and all evaluated preclinical species, for a series of TYK2 inhibitors which target the ATP binding site.

Design and optimization of a series of 4-(3-azabicyclo[3.1.0]hexan-3-yl)pyrimidin-2-amines: Dual inhibitors of TYK2 and JAK1.

Herein, we disclose a new series of TYK2/ JAK1 inhibitors based upon a 3.1.0 azabicyclic substituted pyrimidine scaffold. We illustrate the use of structure-based drug design for the initial design and subsequent optimization of this series of compounds. One advanced example 19 met program objectives for potency, selectivity and ADME, and demonstrated oral activity in the adjuvant-induced arthritis rat model.

Molecular and Cellular Responses to the TYK2/JAK1 Inhibitor PF-06700841 Reveal Reduction of Skin Inflammation in Plaque Psoriasis.

The IL-23/T helper type 17 cell axis is a target for psoriasis. The TYK2/Janus kinase 1 inhibitor PF-06700841 will directly suppress TYK2-dependent IL-12 and IL-23 signaling and Janus kinase 1-dependent signaling in cells expressing these signaling molecules, including T cells and keratinocytes. This clinical study sought to define the inflammatory gene and cellular pathways through which PF-06700841 improves the clinical manifestations of psoriasis. Patients (n = 30) with moderate-to-severe psoriasis were randomized to once-daily 30 mg (n = 14) or 100 mg (n = 7) PF-06700841 or placebo (n = 9) for 28 days. Biopsies were taken from nonlesional and lesional skin at baseline and weeks 2 and 4. Changes in the psoriasis transcriptome and genes induced by IL-17 in keratinocytes were evaluated with microarray profiling and reverse transcriptase-PCR. Reductions in IL-17A, IL-17F, and IL-12B mRNA were observed as early as 2 weeks and approximately 70% normalization of lesional gene expression after 4 weeks. Immunohistochemistry showed significant decreases in markers of keratinocyte activation, epidermal thickness, KRT16 and Ki-67 expression, and immune cell infiltrates CD3+/CD8+ (T cells) and CD11c (dendritic cells) after 2 weeks of treatment, corresponding with improvement in histologic score. PF-06700841 improves clinical symptoms of chronic plaque psoriasis by inhibition of proinflammatory cytokines that require TYK2 and Janus kinase 1 for signal transduction.

Evaluation of the Short-, Mid-, and Long-Term Effects of Tofacitinib on Lymphocytes in Patients With Rheumatoid Arthritis.

OBJECTIVE: Tofacitinib is an oral JAK inhibitor for the treatment of rheumatoid arthritis (RA). Altered lymphocyte cell counts and a potential association with increased infection rates have been reported in RA patients treated with JAK inhibitors. This analysis was undertaken to evaluate the short-, mid-, and long-term effects of tofacitinib on lymphocytes and infection rates in patients with RA. METHODS: In this post hoc analysis, absolute lymphocyte counts (ALCs) were obtained from phase III studies (12-24 months; n = 717-958) and phase I/II/III/long-term extension studies of tofacitinib (≤117 months) (All RA population; n = 7,061); lymphocyte subset counts (LSCs) were from phase II studies (1.5-6 months' exposure; n = 236-486), an ORAL Sequel vaccine substudy (~22 months; n = 198), and an ORAL Sequel lymphocyte substudy (~50 months; n = 55-1,035) of tofacitinib. The reversibility of ALC/LSC changes was evaluated. The relationship of ALC and LSC to infections was analyzed in the All RA population. The value of monitoring ALC alone was assessed by examining correlations between ALCs and LSCs. RESULTS: Tofacitinib treatment resulted in an initial increase in ALC versus pretreatment baseline, which gradually declined to steady state by ~48 months. CD4+ and CD8+ T cell counts decreased over long-term treatment, and ALC and LSC changes were reversible upon treatment cessation. Patients with ALCs of <500 cells/mm3 had an increased risk of serious infections. There was no strong association between CD4+ T cell, CD8+ T cell, B cell, or natural killer cell counts and serious infection incidence rates. ALC and CD4+ or CD8+ T cell counts correlated well (R = 0.65-0.86). CONCLUSION: Our findings indicate that monitoring of ALC alone appears to be adequate to assess infection risk in tofacitinib-treated patients with RA.

Dual Inhibition of TYK2 and JAK1 for the Treatment of Autoimmune Diseases: Discovery of (( S)-2,2-Difluorocyclopropyl)((1 R,5 S)-3-(2-((1-methyl-1 H-pyrazol-4-yl)amino)pyrimidin-4-yl)-3,8-diazabicyclo[3.2.1]octan-8-yl)methanone (PF-06700841).

Cytokine signaling is an important characteristic of autoimmune diseases. Many pro-inflammatory cytokines signal through the Janus kinase (JAK)/Signal transducer and activator of transcription (STAT) pathway. JAK1 is important for the γ-common chain cytokines, interleukin (IL)-6, and type-I interferon (IFN) family, while TYK2 in addition to type-I IFN signaling also plays a role in IL-23 and IL-12 signaling. Intervention with monoclonal antibodies (mAbs) or JAK1 inhibitors has demonstrated efficacy in Phase III psoriasis, psoriatic arthritis, inflammatory bowel disease, and rheumatoid arthritis studies, leading to multiple drug approvals. We hypothesized that a dual JAK1/TYK2 inhibitor will provide additional efficacy, while managing risk by optimizing selectivity against JAK2 driven hematopoietic changes. Our program began with a conformationally constrained piperazinyl-pyrimidine Type 1 ATP site inhibitor, subsequent work led to the discovery of PF-06700841 (compound 23), which is in Phase II clinical development (NCT02969018, NCT02958865, NCT03395184, and NCT02974868).

Reversibility of peripheral blood leukocyte phenotypic and functional changes after exposure to and withdrawal from tofacitinib, a Janus kinase inhibitor, in healthy volunteers.

This study evaluated the short-term effects of tofacitinib treatment on peripheral blood leukocyte phenotype and function, and the reversibility of any such effects following treatment withdrawal in healthy volunteers. Cytomegalovirus (CMV)-seropositive subjects received oral tofacitinib 10 mg twice daily for 4 weeks and were followed for 4 weeks after drug withdrawal. There were slight increases in total lymphocyte and total T-cell counts during tofacitinib treatment, and B-cell counts increased by up to 26%. There were no significant changes in granulocyte or monocyte counts, or granulocyte function. Naïve and central memory T-cell counts increased during treatment, while all subsets of activated T cells were decreased by up to 69%. T-cell subsets other than effector memory cluster of differentiation (CD)4+, activated naïve CD4+ and effector CD8+ T-cell counts and B-cell counts, normalized 4 weeks after withdrawal. Following ex vivo activation, measures of CMV-specific T-cell responses, and antigen non-specific T-cell-mediated cytotoxicity and interferon (IFN)-γ production, decreased slightly. These T-cell functional changes were most pronounced at Day 15, partially normalized while still on tofacitinib and returned to baseline after drug withdrawal. Total natural killer (NK)-cell counts decreased by 33%, returning towards baseline after drug withdrawal. NK-cell function decreased during tofacitinib treatment, but without a consistent time course across measured parameters. However, markers of NK-cell-mediated cytotoxicity, antibody-dependent cellular cytotoxicity and IFN-γ production were decreased up to 42% 1 month after drug withdrawal. CMV DNA was not detectable in whole blood, and there were no cases of herpes zoster reactivation. No new safety concerns arose. In conclusion, the effect of short-term tofacitinib treatment on leukocyte composition and function in healthy CMV+ volunteers is modest and largely reversible 4 weeks after withdrawal.

Identification of N-{cis-3-[Methyl(7H-pyrrolo[2,3-d]pyrimidin-4-yl)amino]cyclobutyl}propane-1-sulfonamide (PF-04965842): A Selective JAK1 Clinical Candidate for the Treatment of Autoimmune Diseases.

Janus kinases (JAKs) are intracellular tyrosine kinases that mediate the signaling of numerous cytokines and growth factors involved in the regulation of immunity, inflammation, and hematopoiesis. As JAK1 pairs with JAK2, JAK3, and TYK2, a JAK1-selective inhibitor would be expected to inhibit many cytokines involved in inflammation and immune function while avoiding inhibition of the JAK2 homodimer regulating erythropoietin and thrombopoietin signaling. Our efforts began with tofacitinib, an oral JAK inhibitor approved for the treatment of rheumatoid arthritis. Through modification of the 3-aminopiperidine linker in tofacitinib, we discovered highly selective JAK1 inhibitors with nanomolar potency in a human whole blood assay. Improvements in JAK1 potency and selectivity were achieved via structural modifications suggested by X-ray crystallographic analysis. After demonstrating efficacy in a rat adjuvant-induced arthritis (rAIA) model, PF-04965842 (25) was nominated as a clinical candidate for the treatment of JAK1-mediated autoimmune diseases.

Discovery of a JAK3-Selective Inhibitor: Functional Differentiation of JAK3-Selective Inhibition over pan-JAK or JAK1-Selective Inhibition.

PF-06651600, a newly discovered potent JAK3-selective inhibitor, is highly efficacious at inhibiting γc cytokine signaling, which is dependent on both JAK1 and JAK3. PF-06651600 allowed the comparison of JAK3-selective inhibition to pan-JAK or JAK1-selective inhibition, in relevant immune cells to a level that could not be achieved previously without such potency and selectivity. In vitro, PF-06651600 inhibits Th1 and Th17 cell differentiation and function, and in vivo it reduces disease pathology in rat adjuvant-induced arthritis as well as in mouse experimental autoimmune encephalomyelitis models. Importantly, by sparing JAK1 function, PF-06651600 selectively targets γc cytokine pathways while preserving JAK1-dependent anti-inflammatory signaling such as the IL-10 suppressive functions following LPS treatment in macrophages and the suppression of TNFα and IL-1ß production in IL-27-primed macrophages. Thus, JAK3-selective inhibition differentiates from pan-JAK or JAK1 inhibition in various immune cellular responses, which could potentially translate to advantageous clinical outcomes in inflammatory and autoimmune diseases.

Network pharmacology of JAK inhibitors.

Small-molecule inhibitors of the Janus kinase family (JAKis) are clinically efficacious in multiple autoimmune diseases, albeit with increased risk of certain infections. Their precise mechanism of action is unclear, with JAKs being signaling hubs for several cytokines. We assessed the in vivo impact of pan- and isoform-specific JAKi in mice by immunologic and genomic profiling. Effects were broad across the immunogenomic network, with overlap between inhibitors. Natural killer (NK) cell and macrophage homeostasis were most immediately perturbed, with network-level analysis revealing a rewiring of coregulated modules of NK cell transcripts. The repression of IFN signature genes after repeated JAKi treatment continued even after drug clearance, with persistent changes in chromatin accessibility and phospho-STAT responsiveness to IFN. Thus, clinical use and future development of JAKi might need to balance effects on immunological networks, rather than expect that JAKis affect a particular cytokine response and be cued to long-lasting epigenomic modifications rather than by short-term pharmacokinetics.

Tofacitinib attenuates pathologic immune pathways in patients with psoriasis: A randomized phase 2 study.

BACKGROUND: Tofacitinib is an oral Janus kinase inhibitor being investigated for psoriasis. OBJECTIVE: We sought to elucidate the molecular mechanisms underlying the clinical efficacy of tofacitinib in patients with psoriasis. METHODS: Twelve patients with plaque psoriasis were randomized (3:1) to receive 10 mg of tofacitinib or placebo twice daily for 12 weeks. Biopsy specimens were taken from nonlesional (baseline) and lesional (baseline, days 1 and 3, and weeks 1, 2, 4, and 12) skin. Biopsy specimens were examined for psoriatic epidermal features (thickness, Ki67(+) keratinocytes and keratin 16 [KRT16] mRNA expression, and phosphorylated signal transducer and activator of transcription [pSTAT](+) nuclei) and T-cell and dendritic cell (DC) subsets by using immunohistochemistry, and mRNA transcripts were quantified by using a microarray. RESULTS: In lesional skin keratinocyte pSTAT1 and pSTAT3 staining was increased at baseline but reduced after 1 day of tofacitinib (baseline, median of 1290 pSTAT1(+) cells/µm(2); day 1, median of 332 pSTAT1(+) cells/µm(2); and nonlesional, median of 155 pSTAT1(+) cells/µm(2)). Epidermal thickness and KRT16 mRNA expression were significantly and progressively reduced after days 1 and 3 of tofacitinib administration, respectively (eg, KRT16 decreased 2.74-fold, day 3 vs baseline, P = .016). Decreases in DC and T-cell numbers were observed after weeks 1 and 2, respectively. At week 4, significant decreases in IL-23/TH17 pathways were observed that persisted through week 12. Improvements in clinical and histologic features were strongly associated with changes in expression of psoriasis-related genes and reduction in IL-17 gene expression. CONCLUSIONS: Tofacitinib has a multitiered response in patients with psoriasis: (1) rapid attenuation of keratinocyte Janus kinase/STAT signaling; (2) removal of keratinocyte-induced cytokine signaling, leading to reductions in pathologic DC and T-cell numbers to nonlesional levels; and (3) inhibition of the IL-23/TH17 pathway.

The mechanism of action of tofacitinib - an oral Janus kinase inhibitor for the treatment of rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease characterised by infiltration of immune cells into the affected synovium, release of inflammatory cytokines and degradative mediators, and subsequent joint damage. Both innate and adaptive arms of the immune response play a role, with activation of immune cells leading to dysregulated expression of inflammatory cytokines. Cytokines work within a complex regulatory network in RA, signalling through different intracellular kinase pathways to modulate recruitment, activation and function of immune cells and other leukocytes. As our understanding of RA has advanced, intracellular signalling pathways such as Janus kinase (JAK) pathways have emerged as key hubs in the cytokine network and, therefore, important as therapeutic targets. Tofacitinib is an oral JAK inhibitor for the treatment of RA. Tofacitinib is a targeted small molecule, and an innovative advance in RA therapy, which modulates cytokines critical to the progression of immune and inflammatory responses. Herein we describe the mechanism of action of tofacitinib and the impact of JAK inhibition on the immune and inflammatory responses in RA.

Parsing the Interferon Transcriptional Network and Its Disease Associations.

Type 1 interferon (IFN) is a key mediator of organismal responses to pathogens, eliciting prototypical "interferon signature genes" that encode antiviral and inflammatory mediators. For a global view of IFN signatures and regulatory pathways, we performed gene expression and chromatin analyses of the IFN-induced response across a range of immunocyte lineages. These distinguished ISGs by cell-type specificity, kinetics, and sensitivity to tonic IFN and revealed underlying changes in chromatin configuration. We combined 1,398 human and mouse datasets to computationally infer ISG modules and their regulators, validated by genetic analysis in both species. Some ISGs are controlled by Stat1/2 and Irf9 and the ISRE DNA motif, but others appeared dependent on non-canonical factors. This regulatory framework helped to interpret JAK1 blockade pharmacology, different clusters being affected under tonic or IFN-stimulated conditions, and the IFN signatures previously associated with human diseases, revealing unrecognized subtleties in disease footprints, as affected by human ancestry.

Milbemycin oxime (Interceptor) treatment of amphipod parasites (Hyperiidae) from several host jellyfish species.

Wild-caught crystal jellyfish (Aequorea victoria) arrived at the John G. Shedd Aquarium infested with hyperiid amphipods (Hyperia medusarum), which were inadvertently introduced into a system containing several jellyfish species. Affected systems were treated with milbemycin oxime (Interceptor tablets for dogs 51-100 lbs, Novartis Animal Health US, Inc., Greensboro, North Carolina 27408, USA), a treatment prescribed for red bug (Tegastes acroporanus) infestation in corals. Two treatments using one 25-mg aliquot of Interceptor per 10 gallons of tank water administered 6-7 days apart were completed. Overall, treatment to eradicate the parasite from the affected systems was successful. Further studies evaluating the tolerance of jellyfish to milbemycin oxime, particularly in small juvenile Eutonina indicans and Aurelia aurita, are warranted. Based on clinical observations, there were more negative effects associated with the treatment in the hydrozoans than in the scyphozoans.

Discovery and development of Janus kinase (JAK) inhibitors for inflammatory diseases.

The Janus kinases (JAKs) are a family of intracellular tyrosine kinases that play an essential role in the signaling of numerous cytokines that have been implicated in the pathogenesis of inflammatory diseases. As a consequence, the JAKs have received significant attention in recent years from the pharmaceutical and biotechnology industries as therapeutic targets. Here, we provide a review of the JAK pathways, the structure, function, and activation of the JAK enzymes followed by a detailed look at the JAK inhibitors currently in the clinic or approved for these indications. Finally, a perspective is provided on what the past decade of research with JAK inhibitors for inflammatory indications has taught along with thoughts on what the future may hold in terms of addressing the opportunities and challenges that remain.

Variants within STAT genes reveal association with anticitrullinated protein antibody-negative rheumatoid arthritis in 2 European populations.

OBJECTIVE: STAT3 and 4 are, among other factors, critical for the interleukin 12 (IL-12)-mediated Th1 response, for transfer of IL-23 signals, and for survival and expansion of Th17 cells. We investigated the association of STAT3 and STAT4 polymorphisms with serologically distinct subgroups of rheumatoid arthritis (RA). METHODS: A total of 41 single-nucleotide polymorphisms (SNP) within STAT3 and STAT1-STAT4 loci were investigated in a Swedish cohort of 2043 RA cases and 1115 controls. Nine of the associated SNP were tested in a Spanish cohort of 1223 RA cases and 1090 controls. RESULTS: Fourteen SNP in the STAT3 and STAT1-STAT4 loci were associated with anticitrullinated protein antibody (ACPA)-negative RA in the Swedish cohort. Three of the SNP in STAT4 and 2 SNP in STAT3 remained associated with ACPA-negative RA after considering the Spanish results. In addition, rs7574865 and rs10181656, in STAT4, were associated with ACPA-positive RA in the Swedish study. One of these SNP, rs7574865, showed a similar pattern of the association in serologically distinct subgroups of RA in a metaanalysis of all 7 published studies. CONCLUSION: Our findings suggest that variants in STAT genes may contribute differentially to susceptibility to RA in seropositive and in seronegative patients.