Innate and adaptive immune cell interaction drives inflammasome activation and hepatocyte apoptosis in murine liver injury from immune checkpoint inhibitors.

Immune checkpoints (CTLA4 & PD-1) are inhibitory pathways that block aberrant immune activity and maintain self-tolerance. Tumors co-opt these checkpoints to avoid immune destruction. Immune checkpoint inhibitors (ICIs) activate immune cells and restore their tumoricidal potential, making them highly efficacious cancer therapies. However, immunotolerant organs such as the liver depend on these tolerogenic mechanisms, and their disruption with ICI use can trigger the unintended side effect of hepatotoxicity termed immune-mediated liver injury from ICIs (ILICI). Learning how to uncouple ILICI from ICI anti-tumor activity is of paramount clinical importance. We developed a murine model to recapitulate human ILICI using CTLA4+/- mice treated with either combined anti-CTLA4 + anti-PDL1 or IgG1 + IgG2. We tested two forms of antisense oligonucleotides to knockdown caspase-3 in a total liver (parenchymal and non-parenchymal cells) or in a hepatocyte-specific manner. We also employed imaging mass cytometry (IMC), a powerful multiplex modality for immunophenotyping and cell interaction analysis in our model. ICI-treated mice had significant evidence of liver injury. We detected cleaved caspase-3 (cC3), indicating apoptosis was occurring, as well as Nod-like receptor protein 3 (NLRP3) inflammasome activation, but no necroptosis. Total liver knockdown of caspase-3 worsened liver injury, and induced further inflammasome activation, and Gasdermin-D-mediated pyroptosis. Hepatocyte-specific knockdown of caspase-3 reduced liver injury and NLRP3 inflammasome activation. IMC-generated single-cell data for 77,692 cells was used to identify 22 unique phenotypic clusters. Spatial analysis revealed that cC3+ hepatocytes had significantly closer interactions with macrophages, Kupffer cells, and NLRP3hi myeloid cells than other cell types. We also observed zones of three-way interaction between cC3+ hepatocytes, CD8 + T-cells, and macrophages. Our work is the first to identify hepatocyte apoptosis and NLRP3 inflammasome activation as drivers of ILICI. Furthermore, we report that the interplay between adaptive and innate immune cells is critical to hepatocyte apoptosis and ILICI.

Isoform-specific knockdown of long and intermediate prolactin receptors interferes with evolution of B-cell neoplasms.

Prolactin (PRL) is elevated in B-cell-mediated lymphoproliferative diseases and promotes B-cell survival. Whether PRL or PRL receptors drive the evolution of B-cell malignancies is unknown. We measure changes in B cells after knocking down the pro-proliferative, anti-apoptotic long isoform of the PRL receptor (LFPRLR) in vivo in systemic lupus erythematosus (SLE)- and B-cell lymphoma-prone mouse models, and the long plus intermediate isoforms (LF/IFPRLR) in human B-cell malignancies. To knockdown LF/IFPRLRs without suppressing expression of the counteractive short PRLR isoforms (SFPRLRs), we employ splice-modulating DNA oligomers. In SLE-prone mice, LFPRLR knockdown reduces numbers and proliferation of pathogenic B-cell subsets and lowers the risk of B-cell transformation by downregulating expression of activation-induced cytidine deaminase. LFPRLR knockdown in lymphoma-prone mice reduces B-cell numbers and their expression of BCL2 and TCL1. In overt human B-cell malignancies, LF/IFPRLR knockdown reduces B-cell viability and their MYC and BCL2 expression. Unlike normal B cells, human B-cell malignancies secrete autocrine PRL and often express no SFPRLRs. Neutralization of secreted PRL reduces the viability of B-cell malignancies. Knockdown of LF/IFPRLR reduces the growth of human B-cell malignancies in vitro and in vivo. Thus, LF/IFPRLR knockdown is a highly specific approach to block the evolution of B-cell neoplasms.

B Cell and T Cell Dissimilarities in BAFF-Deficient versus BR3-Deficient C57BL/6 Mice.

BAFF is a potent B cell survival and differentiation factor with three receptors, TACI, BCMA, and BR3. B cells are greatly reduced in BAFF-deficient mice, and among mice deficient in a single BAFF receptor, B cell reduction is characteristic only of BR3-deficient mice. Nevertheless, there may be important differences between BR3-deficient mice, in which interactions between BAFF and only BR3 are abrogated, and BAFF-deficient mice, in which interactions between BAFF and all its receptors are abrogated. We demonstrate that: 1) the numbers of CD19+ cells in C57BL/6 (B6).Baff-/- and B6.Br3-/- mice diverge as the mice age; 2) the distribution of B cell subsets significantly differ between B6.Baff-/- and B6.Br3-/- mice regardless of age or sex; 3) the relationships of CD3+ and CD4+ cells to B cells vastly differ between B6.Baff-/- and B6.Br3-/- mice as a function of age and sex; 4) the numbers and percentages of CD4+Foxp3+ and CD4+CD25+Foxp3+ are greater in B6.Baff-/- mice than in B6.Br3-/- mice; and 5) for any given number of CD19+ cells or CD4+ cells, percentages of Foxp3+ cells and CD4+CD25+Foxp3+ cells are lower in B6.Br3-/- mice than in B6.Baff-/- mice, with proliferation of these cells being greater, and survival being lesser, in B6.Br3-/- mice than in B6.Baff-/- mice. Collectively, these observations raise the possibility that interactions between TACI and/or BCMA and BAFF modulate expression of B cell subsets and Foxp3+ cells and may help explain prior enigmatic observations of autoimmunity and autoimmune disease in mice despite the absence of functional engagement of BR3 by BAFF.

Preferential Expansion of Foxp3+ T Regulatory Cells in CTLA-4-Deficient and CTLA-4-Haploinsufficient C57BL/6 Mice.

Foxp3+ cells and CTLA-4 have been ascribed major roles in downregulating immune responses. To address the relationship between CTLA-4 expression and Foxp3+ cells, we generated littermate CTLA-4-sufficient (Ctla4 +/+), CTLA-4-haploinsufficient (Ctla4 +/-), and CTLA-4-deficient (Ctla4 -/-) Foxp3-gfp knock-in C57BL/6 mice, permitting us to characterize the phenotype of Foxp3+ cells and to test their ex vivo T regulatory (Treg) suppressor activity. CD3+, CD4+, and CD8+ cells, but not CD19+ cells, were markedly expanded in Ctla4 -/- mice compared with Ctla4 +/+ or Ctla4 +/- mice. In Ctla4 -/- mice, the relative expansion of the Foxp3+ population was greater than that of the CD3+, CD4+, or CD8+ populations because of increased survival of Foxp3+ cells. Foxp3+ Treg cells from Ctla4 -/- mice and Foxp3+ Treg cells from Ctla4 +/+ mice exerted identical ex vivo suppressor function. This may be related to differential expression of GITR, CD73, and CD39 on Foxp3+ Treg cells from Ctla4 -/- mice versus that on corresponding cells from littermate Ctla4 +/+ or Ctla4 +/- mice, with GITR and CD39 being upregulated and CD73 being downregulated on Foxp3+ Treg cells from Ctla4 -/- mice. Moreover, CTLA-4 expression in Ctla4 +/+, Ctla4 +/-, and Ctla4 -/- mice correlated with their percentages of Foxp3+ cells, suggesting an important role for CTLA-4 expression in Treg cell homeostasis. This may have vital ramifications for the treatment of patients for whom augmentation of suppressor function would be beneficial (e.g., patients with autoimmune diseases) and for whom diminution of suppressor function would be beneficial (e.g., patients with cancer).

Impact of Belimumab on Organ Damage in Systemic Lupus Erythematosus.

Organ damage is a key determinant of poor long-term prognosis and early death in patients with systemic lupus erythematosus (SLE). Prevention of damage is a key treatment goal of the 2019 update of the European Alliance of Associations for Rheumatology (EULAR) recommendations for SLE management. Belimumab is a monoclonal antibody that inhibits B lymphocyte stimulator (BLyS) and is the only therapy approved for both SLE and lupus nephritis. Here, we review the clinical trial and real-world data on the effects of belimumab on organ damage in adult patients with SLE. Across 4 phase III studies, belimumab in combination with background SLE therapy demonstrated consistent reductions in key drivers of organ damage including disease activity, risk of new severe flares, and glucocorticoid exposure compared to background therapy alone. Long-term belimumab use in SLE also reduced organ damage progression measured by the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index, as reported in open-label extension studies, and propensity score-matched comparative analyses to background therapy alone. Results from a clinical trial showed that in patients with active lupus nephritis, belimumab treatment improved renal response, reduced the risk of renal-related events, and impacted features related to kidney damage progression compared to background therapy alone. The decrease of organ damage accumulation observed with belimumab treatment in SLE, including lupus nephritis, suggest a disease-modifying effect.

Reductions in circulating B cell subsets and immunoglobulin G levels with long-term belimumab treatment in patients with SLE.

OBJECTIVE: To examine the long-term changes in circulating B cell subsets and IgG levels at 5+ years of continuous belimumab treatment and their correlations with efficacy and safety measures. METHODS: This was a post hoc analysis of a continuation study (BEL112233; NCT00724867) of eligible US patients who completed the 76-week BLISS-76 Study (BEL110751; NCT00410384), with up to eight calendar-years of follow-up and median (IQR) belimumab exposure of 310 (209, 364) weeks. From week 76, patients initially randomised to intravenous belimumab 1 mg/kg or 10 mg/kg every 4 weeks in BLISS-76 continued to receive the same dose in the continuation study, while those initially randomised to placebo received belimumab 10 mg/kg intravenous every 4 weeks during continuation. All patients continued to receive standard SLE therapy. Biomarker data were collected, and the effects on baseline and early changes (weeks 0-24 after starting belimumab) from baseline in biomarkers on SLE Responder Index (SRI-4) and infection rate were evaluated. RESULTS: Of the 819 patients from BLISS-76, 268 self-selecting patients entered BEL112233. Compared with baseline, B cell subset counts decreased by 40%-99% after 312 weeks (6 years), and serum IgG levels decreased by 28% after 284 weeks. Higher baseline naïve B cell counts were associated with greater SRI-4 response rates (p<0.05), whereas higher baseline SLE subset plasma and short-lived plasma B cell counts were associated with lower SRI-4 response rates (p<0.05). Elevated baseline IgG levels were associated with increased infection rates over the treatment period (p<0.05), and early greater decreases in IgG levels were associated with higher SRI-4 response rates (p<0.05). CONCLUSIONS: Belimumab treatment up to 312 weeks (6 years) resulted in substantial decreases in several circulating B cell subsets and IgG levels. Higher baseline naïve B cell counts and IgG levels were associated with improved SRI-4 response and increased infection rates, respectively.

First-trimester serum BAFF:sFlt-1 ratio as a candidate early biomarker of spontaneous abortion.

PROBLEM: Immunologic, angiogenic, and anti-angiogenic factors are associated with spontaneous abortion (SAB). B cell-activating factor (BAFF), a proliferation-inducing ligand (APRIL), placental growth factor (PlGF), and soluble fms-like tyrosine kinase-1 (sFlt-1) may play a role in SAB and may serve singly or in combination as an early biomarker of SAB. METHOD OF STUDY: In this prospective observational study, serum sFlt-1, PIGF, BAFF, and APRIL levels were measured in the first trimester of pregnancy in a medically diverse group of women and in non-pregnant controls. Associations and discriminative values of first-trimester sFlt-1, PIGF, BAFF, and APRIL levels and the corresponding APRIL:BAFF, BAFF:sFlt-1, and sFlt-1:PlGF ratios with development of SAB were tested. RESULTS: Median serum BAFF level was lower (p = .007) and median serum sFlt-1 level was higher (p < .001), in the first trimester of pregnancy than in non-pregnant controls. SAB developed in 27 of the pregnant women (11.3%), and first-trimester levels of BAFF (but not APRIL) and sFlt-1 (but not PIGF) were associated with SAB. Using optimal cutoffs determined through receiver operating characteristics curves, the best discriminator of SAB was the serum BAFF:sFlt-1 ratio, specifically among non-nulliparous women and women with prior SAB. CONCLUSION: First-trimester serum BAFF:sFlt-1 ratio is a candidate indicator/predictor of SAB among non-nulliparous women and women with prior SAB. If validated through additional studies, then early identification of pregnant women at high risk for SAB through this simple blood test would assist in counseling and facilitate clinical trials of therapeutic interventions.

Mortality and adverse events of special interest with intravenous belimumab for adults with active, autoantibody-positive systemic lupus erythematosus (BASE): a multicentre, double-blind, randomised, placebo-controlled, phase 4 trial.

BACKGROUND: Belimumab is approved for the treatment of active systemic lupus erythematosus (SLE). Although clinical trials showed a favourable benefit-risk profile, numerical differences in the incidence of mortality and adverse events of special interest (AESIs) have been reported. We assessed the frequency of these events in patients with SLE receiving belimumab or placebo plus standard therapy. METHODS: BASE was a double-blind, randomised, placebo-controlled, phase 4 trial done in 33 countries. Adults with active SLE were randomly assigned (1:1) to receive intravenous belimumab (10 mg/kg) or placebo, plus standard therapy, for 48 weeks. The primary endpoints were incidences of all-cause mortality and AESIs during the on-treatment period (first-to-last study drug dose + 28 days). Safety analyses were done in the as-treated population (patients grouped by actual treatment received >50% of the time). This study was registered with ClinicalTrials.gov (NCT01705977). FINDINGS: Between Nov 27, 2012, and July 28, 2017, we randomly assigned 4018 patients. The as-treated population included 2002 patients in the belimumab group versus 2001 in the placebo group. Ten (0·50%) patients in the belimumab group died versus eight (0·40%) in the placebo group (difference 0·10%, 95% CI -0·31 to 0·51). Incidences were similar in the belimumab and placebo groups for serious infections (75 [3·75%] of 2002 vs 82 [4·10%] of 2001; difference -0·35%, 95% CI -1·55 to 0·85), opportunistic infections and other infections of interest (36 [1·80%] vs 50 [2·50%]; -0·70%, -1·60 to 0·20), non-melanoma skin cancers (4 [0·20%] vs 3 [0·15%]; 0·05%, -0·21 to 0·31) and other malignancies (5 [0·25%] vs 5 [0·25%]; 0·00%, -0·31 to 0·31). A higher proportion of patients in the belimumab group than in the placebo group had infusion and hypersensitivity reactions (8 [0·40%] vs 2 [0·10%]; 0·30%, -0·01 to 0·61), serious depression (7 [0·35%] vs 1 [0·05%]; 0·30%, 0·02 to 0·58), treatment-emergent suicidality (28 [1·42%] of 1972 patients vs 23 [1·16%] of 1986; 0·26%, -0·44 to 0·96), and sponsor-adjudicated serious suicide or self-injury (15 [0·75%] of 1972 patients vs 5 [0·25%] of 1986; post hoc difference 0·50%, 0·06 to 0·94). INTERPRETATION: In line with previously published data, incidences of all-cause mortality and AESIs were similar in patients given belimumab and placebo, except for serious infusion or hypersensitivity reactions, serious depression, treatment-emergent suicidality, and sponsor-adjudicated serious suicide or self-injury events. FUNDING: GSK.

Circulating TNF-like protein 1A (TL1A) is elevated early in rheumatoid arthritis and depends on TNF.

BACKGROUND: The tumor necrosis factor (TNF) superfamily cytokine TNF-like protein 1A (TL1A) and its receptor DR3 are essential for diverse animal models of autoimmune disease and may be pathogenic in rheumatoid arthritis (RA). However, the relationship of TL1A to disease duration, activity, and response to anti-TNF and other therapies in RA is not clear. METHODS: We measured soluble TL1A in synovial fluid (SF), serum, or plasma from RA first-degree relatives (FDRs) and in early RA and established disease. We measured the effects of anti-TNF and methotrexate (MTX) therapy on circulating TL1A from multiple independent RA treatment trials. We also determined the ability of a blocking anti-TL1A antibody to inhibit clinical disease and articular bone destruction in the murine collagen-induced arthritis (CIA) model of human RA. RESULTS: Soluble TL1A was specifically elevated in the blood and SF of patients with RA compared to patients with other diseases and was elevated early in disease and in at-risk anti-cyclic citrullinated peptide (CCP) (+) first-degree relatives (FDRs). Therapeutic TNF inhibition reduced serum TL1A in both responders and non-responders, whereas TL1A declined following MTX treatment only in responders. In murine CIA, TL1A blockade was clinically efficacious and reduced bone erosions. CONCLUSIONS: TL1A is specifically elevated in RA from early in the disease course and in at-risk FDRs. The decline in TL1A after TNF blockade suggests that TL1A levels may be a useful biomarker for TNF activity in RA. These results support the further investigation of the relationship between TL1A and TNF and TL1A blockade as a potential therapeutic strategy in RA.

Promotion of T Regulatory Cells in Mice by B Cells and BAFF.

In addition to promoting B cell expansion, overexpression of BAFF promotes expansion of T cells, including T regulatory (Treg) cells. To determine the relationships among BAFF, B cells, and Treg cells, a panel of C57BL/6 (B6) congenic mice was tested. Treg cells were disproportionately expanded in mice expressing a Baff transgene (B6.BTg) and were disproportionately contracted in mice deficient in BAFF (B6.Baff-/- ). In vitro suppressor activities of B6 wild-type, B6.BTg, and B6.Baff-/- Treg cells were identical, as was in vitro generation of Treg cells. In vivo proliferation of Treg cells was greatest in B6.BTg mice, whereas in vivo survival of Treg cells was lowest in B6.Baff-/- mice. B cells promoted BAFF-independent Treg cell expansion in vivo, as evidenced by the correlation between B cells and percentages of Treg cells in B6.Baff-/- mice and by the greater percentages of Treg cells in B6.Bcl2Tg mice (which harbor B cells largely independent of BAFF because of expression of a Bcl2 transgene) than in B6 wild-type mice despite the lower serum BAFF levels in the former than in the latter. Experiments with BAFF-deficient B6.Baff-/- Bcl2Tg mice, B cell-deficient B6.µMT mice, BAFF-overexpressing/B cell-deficient B6.BTg.µMT mice, and BAFF-deficient/B cell-deficient B6.Baff-/- µMT mice demonstrated that, in a host that harbors B cells, the effect of BAFF on Treg cells goes beyond its ability to expand the B cell population and is additional to the BAFF-independent effect of B cells on Treg cells. These findings may have considerable relevance to the treatment of B cell-associated autoimmune diseases.

Development of Murine Systemic Lupus Erythematosus in the Absence of BAFF.

OBJECTIVE: To determine whether systemic lupus erythematosus (SLE) can develop in the absence of BAFF in an SLE-prone host. METHODS: Starting with C57BL/6 mice that express a human BCL2 transgene (Tg) in their B cells (thereby rendering B cell survival largely independent of BAFF-triggered signals), we introgressed this Tg into NZM 2328 mice genetically deficient in BAFF (NZM.Baff-/- ) to generate NZM.Baff-/- .Bcl2Tg mice. Expression of human Bcl-2 and lymphocyte profiles were assessed by fluorescence-activated cell sorting, and serologic profiles were determined by enzyme-linked immunosorbent assay. Immunofluorescence and histologic analyses were performed to assess renal immunopathologic features in the mice, and clinical disease was assessed according to the outcomes of severe proteinuria and death. RESULTS: In comparison to their non-Tg NZM.Baff-/- littermates (n ≥ 7), NZM.Baff-/- .Bcl2Tg mice (n ≥ 8) overexpressed Bcl-2 in their B cells and developed significantly increased percentages and numbers of B cells and plasma cells, serum levels of IgG autoantibodies, glomerular deposition of IgG and C3, and severity of glomerular and tubulointerstitial inflammation, culminating in severe proteinuria and death (all P < 0.05 versus NZM.Baff-/- littermates). The time course for development of SLE-like features in NZM.Baff-/- .Bcl2Tg mice was more rapid than has been previously observed in NZM 2328 wild-type mice (median age at death 4.5 months versus 7.5 months). NZM.Baff-/- .Bcl2Tg mice remained responsive to BAFF, since reintroduction of the Baff gene into these mice further accelerated the course of disease (median age at death 3 months). CONCLUSION: The role of BAFF in the development of SLE-like disease may be dispensable as long as B cell survival is preserved via a BAFF-independent pathway. This may help explain the limited and variable clinical success with BAFF antagonists in human SLE. Thus, NZM.Baff-/- .Bcl2Tg mice may serve as a powerful murine model for the study of BAFF-independent SLE.

Constitutive reduction in the checkpoint inhibitor, CTLA-4, does not accelerate SLE in NZM 2328 mice.

BACKGROUND/OBJECTIVE: Treatment with immune checkpoint inhibitors (ICIs) in oncology patients is increasing. Although ICIs trigger rheumatic immune-related adverse events, development of SLE features has been rare. Whether long-term treatment with ICIs would promote SLE features remains unknown. To begin to address this, we generated SLE-prone NZM 2328 mice with lifelong reduction in CTLA-4 expression. METHODS: Since CTLA-4-deficient (Ctla4- /-) NZM mice developed a lethal lymphoproliferative disorder by 3-6 weeks of age, development of SLE in these mice could not be studied. Ctla4 haploinsufficient NZM.Ctla4+ / - mice were assessed in parallel with littermate female NZM.Ctla4+ / + mice. Evaluations included CTLA-4 expression and lymphocyte profiles, assessed by fluorescence-activated cell sorting; serological profiles, assessed by ELISA; renal immunopathology, assessed by histology and immunofluorescence; and clinical courses, assessed by mortality. RESULTS: CTLA-4 expression was lower in NZM.Ctla4+ / - mice than in NZM.Ctla4+ / + mice. Spleen mononuclear cells, B cells, plasma cells, CD4+ cells, recently activated CD4+ cells and CD4+ T regulatory (Treg) cells were increased in NZM.Ctla4+ / - mice (p≤0.042). The serological profile, degree of renal immunopathology and mortality in NZM.Ctla4+ / - mice remained unaffected. CONCLUSION: Lifelong reduction in CTLA-4 expression in NZM mice neither accelerated nor aggravated SLE. Expansion in Treg cells may have played a protective role. Our observations raise the hope that long-term treatment of patients with SLE with an anti-CTLA-4 agent, should the need arise, would not adversely affect SLE disease activity.

IgM Plasma Cells Reside in Healthy Skin and Accumulate with Chronic Inflammation.

Antibodies are key to cutaneous host defense and inflammation. Despite their importance, the mechanisms by which skin antibodies are sustained are poorly described. Here, we identified that, in addition to antibody production in lymphoid tissues, plasma cells reside in healthy mouse and human skin. In naïve mice, IgM was the predominant isotype produced in skin. Skin plasma cells developed independently of T cells and microbiota. Importantly, chronic skin inflammation promoted the massive accumulation of IgM-secreting cells, and cutaneous immunization directed both T cell-dependent and -independent antigen-specific IgM-secreting cells into skin. Unlike their counterparts in lymphoid tissues, cutaneous IgM-secreting cells were completely dependent on survival factors such as a proliferation-inducing ligand or B cell-activating factor, which were constitutively expressed and upregulated during inflammation in skin. Our data support a model in which skin plasma cells supply natural and adaptive IgM to the cutaneous environment, thereby supporting homeostatic skin barrier functions and providing defense against pathogen intrusion. Our results are also of potential relevance for manipulation of cutaneous plasma cells in inflammatory skin diseases or cutaneous plasma cell malignancies.

Safety and Efficacy of Belimumab Plus Standard Therapy for Up to Thirteen Years in Patients With Systemic Lupus Erythematosus.

OBJECTIVE: To investigate the long-term safety and efficacy of intravenous (IV) belimumab plus standard of care (SOC) therapy for systemic lupus erythematosus (SLE) in patients with active, autoantibody-positive SLE. METHODS: The study was designed as a multicenter, open-label, continuation study of IV belimumab given every 4 weeks in conjunction with SOC therapy in patients with SLE who completed a phase II, double-blind study. Adverse events (AEs) and laboratory data were monitored from the first belimumab dose (in either study) until 24 weeks after the final dose. Efficacy assessments included SLE Responder Index (SRI) and flare index scores (each assessed at 16-week intervals) and glucocorticoid use (assessed at 4-week intervals). RESULTS: Of the 476 patients in the parent study, 298 (62.6%) entered the continuation study, of whom 96 (32.2%) remained in the study. Patients received belimumab for up to 13 years (median duration of exposure 3,334.0 days [range 260-4,332 days], total belimumab exposure 2,294 patient-years, median number of infusions 115.5 [range 7-155]). The percentage of patients with AEs each year remained stable or decreased. Normal serum IgG levels were maintained in the majority of patients over the study, and the rate of infections remained stable. The percentage of patients who achieved an SRI response increased from 32.8% (year 1) to 75.6% of those remaining on treatment at year 12. The glucocorticoid dose was decreased in patients who had been receiving >7.5 mg/day at baseline. CONCLUSION: This study is the longest to date to assess belimumab treatment in patients with SLE in clinical trials. Belimumab was well tolerated with no new safety concerns, and efficacy was maintained in patients who continued the study. For patients who initially exhibited a satisfactory response to belimumab, the treatment continues to be well tolerated and provides long-term disease control.

Increased Cathepsin S activity associated with decreased protease inhibitory capacity contributes to altered tear proteins in Sjögren's Syndrome patients.

Cathepsin S (CTSS) activity is elevated in Sjögren's Syndrome (SS) patient tears. Here we tested whether protease inhibition and cystatin C (Cys C) levels are reduced in SS tears, which could lead to enhanced CTSS-driven degradation of tear proteins. CTSS activity against Cys C, LF and sIgA was tested in SS or healthy control tears. Tears from 156 female subjects (33, SS; 33, rheumatoid arthritis; 31, other autoimmune diseases; 35, non-autoimmune dry eye (DE); 24, healthy controls) were analyzed for CTSS activity and Cys C, LF, and sIgA levels. Cys C and LF showed enhanced degradation in SS tears supplemented with recombinant CTSS, but not supplemented healthy control tears. CTSS activity was significantly increased, while Cys C, LF and sIgA levels were significantly decreased, in SS tears compared to other groups. While tear CTSS activity remained the strongest discriminator of SS in autoimmune populations, combining LF and CTSS improved discrimination of SS beyond CTSS in DE patients. Reductions in Cys C and other endogenous proteases may enhance CTSS activity in SS tears. Tear CTSS activity is reconfirmed as a putative biomarker of SS in an independent patient cohort while combined LF and CTSS measurements may distinguish SS from DE patients.

Maternal Serum B-Cell Activating Factor Levels: Candidate Early Biomarker for Hypertensive Disorders of Pregnancy.

Hypertensive disorders of pregnancy are a leading cause of maternal and perinatal morbidity and mortality. Early suppression of B-cell lymphopoiesis is necessary for a normal pregnancy. Dysregulation of factors critical to B-cell survival may result in pregnancy complications, including hypertension. In this prospective observational study at a single medical center, serum levels of BAFF (B-cell activating factor) were measured in pregnant participants at each trimester, at delivery, and postpartum and in nonpregnant controls at a single time point. Comparisons were made between nonpregnant and pregnant subjects and between time periods of pregnancy. First-trimester serum BAFF levels were further tested for association with hypertensive disorders of pregnancy. The study included 149 healthy pregnant women, 25 pregnant women with chronic hypertension, and 48 nonpregnant controls. Median first-trimester serum BAFF level (ng/mL) for healthy women (0.90) was lower than median serum BAFF levels for women with chronic hypertension (0.96; P=0.013) and controls (1.00; P=0.002). Serum BAFF levels steadily declined throughout pregnancy, with the median second-trimester level lower than the corresponding first-trimester level (0.77; P=0.003) and the median third-trimester level lower than the corresponding second-trimester level (0.72; P=0.025). The median first-trimester serum BAFF level was elevated in women who subsequently developed hypertension compared with women who remained normotensive (1.02 versus 0.85; P=0.012), with the area under the receiver operating characteristic curve being 0.709. First-trimester serum BAFF level may be an early and clinically useful predictor of hypertensive disorders of pregnancy.

A TLR9-dependent checkpoint governs B cell responses to DNA-containing antigens.

Mature B cell pools retain a substantial proportion of polyreactive and self-reactive clonotypes, suggesting that activation checkpoints exist to reduce the initiation of autoreactive B cell responses. Here, we have described a relationship among the B cell receptor (BCR), TLR9, and cytokine signals that regulate B cell responses to DNA-containing antigens. In both mouse and human B cells, BCR ligands that deliver a TLR9 agonist induce an initial proliferative burst that is followed by apoptotic death. The latter mechanism involves p38-dependent G1 cell-cycle arrest and subsequent intrinsic mitochondrial apoptosis and is shared by all preimmune murine B cell subsets and CD27- human B cells. Survival or costimulatory signals rescue B cells from this fate, but the outcome varies depending on the signals involved. B lymphocyte stimulator (BLyS) engenders survival and antibody secretion, whereas CD40 costimulation with IL-21 or IFN-γ promotes a T-bet+ B cell phenotype. Finally, in vivo immunization studies revealed that when protein antigens are conjugated with DNA, the humoral immune response is blunted and acquires features associated with T-bet+ B cell differentiation. We propose that this mechanism integrating BCR, TLR9, and cytokine signals provides a peripheral checkpoint for DNA-containing antigens that, if circumvented by survival and differentiative cues, yields B cells with the autoimmune-associated T-bet+ phenotype.

Inhibition of B cell activating factor (BAFF) in the management of systemic lupus erythematosus (SLE).

INTRODUCTION: The anti-BAFF monoclonal antibody, belimumab, was approved 5+ years ago by the US Food and Drug Administration for the treatment of adult SLE patients. Although BAFF is now a proven therapeutic target in SLE, the limited clinical efficacy both in the clinical trials setting and in 'real-life' experience begs for further therapeutic improvement. Areas covered: In addition to belimumab, three other BAFF antagonists (atacicept, blisibimod, tabalumab) that biologically differ from belimumab are being or have been evaluated in SLE late-stage clinical trials. Literature search was performed using the search words/phrases, 'BAFF', 'BLyS', 'APRIL', 'BCMA', 'TACI', 'BR3', 'belimumab', 'atacicept', 'blisibimod', 'tabalumab', 'lupus clinical trial' along with papers from the author's personal library. Expert commentary: The reasons underlying current lack of enthusiasm among clinicians for BAFF antagonism are discussed, and speculation if offered regarding the use of a BAFF antagonist as part of sequential therapy and regarding the utility of individual or pairs of BAFF receptors as therapeutic targets.

Serum progranulin levels in Hispanic rheumatoid arthritis patients treated with TNF antagonists: a prospective, observational study.

Since progranulin (PGRN) is a natural ligand of TNF receptors, we assessed whether serum PGRN levels predict and/or reflect responsiveness of RA patients to TNF-antagonist therapy. TNF-antagonist-naïve RA patients (N = 35) were started on TNF-antagonist therapy. At baseline and at follow-up visits, DAS28-ESR, DAS28-CRP, and CDAI were calculated, and venous blood was collected for serum PGRN determination. Disease activity and clinical response were based on EULAR criteria. Baseline serum PGRN levels varied considerably and correlated with ESR and CRP. DAS28-ESR, DAS28-CRP, and CDAI were greater in "PGRN-high" than in "PGRN-low". Baseline serum PGRN levels did not predict clinical responsiveness to TNF-antagonist therapy. Nevertheless, changes in serum PGRN levels at 274+ days following initiation of TNF-antagonist therapy correlated with changes in ESR, CRP, DAS28-ESR, DAS28-CRP, and CDAI. At this time, DAS28-ESR, DAS28-CRP, and CDAI in PGRN-high and PGRN-low equalized, but serum PGRN levels remained greater in PGRN-high than in PGRN-low. To our knowledge, the present report is the first prospective study to longitudinally assess changes in serum PGRN levels following initiation of TNF-antagonist therapy. Although pre-treatment serum PGRN levels may not predict clinical responsiveness to TNF-antagonist therapy, changes in serum PGRN levels correlate with changes in disease metrics over time. By inference, administration of PGRN may represent an effective therapeutic option for development in RA patients.