VEXAS syndrome: Clinical manifestations, diagnosis, and treatment.

VEXAS (Vacuoles, E1 enzyme, X-linked, Autoinflammatory, Somatic) syndrome is an adult-onset autoinflammatory syndrome characterized by somatic mutations in the UBA1 gene and is considered the prototype of hematoinflammatory diseases. Patients with VEXAS syndrome exhibit inflammatory and hematological manifestations that can lead to clinical diagnoses such as relapsing polychondritis, polyarteritis nodosa, Sweet syndrome, and myelodysplastic syndrome. Diagnosis requires bone marrow evaluation to identify cytoplasmic vacuoles in myeloid and erythroid precursors. However, genetic confirmation of mutations in UBA1 is necessary. Treatment is challenging and often involves glucocorticoids and immunosuppressants with variable responses. Hypomethylating agents and allogenic haemopoietic stem cell transplant are considered promising therapies. Prognosis is influenced by genetic and clinical factors. The aim of this review is to provide an overview of the pathogenesis, clinical presentation, treatment, and prognosis of VEXAS syndrome for the Latin American medical community.

Ethical considerations in animal research: the principle of 3r's

In the last century, progress in the knowledge of human diseases, their diagnosis and treatment have grown exponentially, due in large part to the introduction and use of laboratory animals. Along with this important progress, the need to provide training and guidance to the scientific community in all aspects related to the proper use of experimental animals has been indispensable. Animal research committees play a primary role in evaluating experimental research protocols, from their feasibility to the rational use of animals, but above all in seeking animal welfare. The Institutional Committee for the Care and Use of Animals (IACUC) has endeavored to share several relevant aspects in conducting research with laboratory animals. Here, we present and discuss the topics that we consider of utmost importance to take in the account during the design of any experimental research protocol, so we invite researchers, technicians, and undergraduate and graduate students to dive into the fascinating subject of proper animal care and use for experimentation. The main intention of these contributions is to sensitize users of laboratory animals for the proper and rational use of them in experimental research, as well as to disseminate the permitted and unpermitted procedures in laboratory animals. In the first part, the significance of experimental research, the main functions of IACUC, and the principle of the three R's (replacement, reduction, and refinement) are addressed.

Fas/FasL Signaling Regulates CD8 Expression During Exposure to Self-Antigens.

Activation of self-reactive CD8+ T cells induces a peripheral tolerance mechanism that involves loss of CD8 expression. Because genetic deficiency of Fas and Fasl causes the accumulation of double-negative (DN; CD3+ TCR-αß+ CD4- CD8-) T cells that have been proposed to derive from CD8+ cells, we decided to explore the role of Fas and FasL in self-antigen-induced CD8 downregulation. To this end, we quantified Fas and FasL induction by different stimuli and analyzed the effects of Fas/FasL deficiency during a protective immune response and after exposure to self-antigens. Our data describes how Fas and FasL upregulation differs depending on the setting of CD8 T cell activation and demonstrates that Fas/FasL signaling maintains CD8 expression during repetitive antigen stimulation and following self-antigen encounter. Together, our results reveal an unexpected role of Fas/FasL signaling and offer a new insight into the role of these molecules in the regulation of immune tolerance.

Protein phosphatase 2A B55ß limits CD8+ T cell lifespan following cytokine withdrawal.

How T cells integrate environmental cues into signals that limit the magnitude and length of immune responses is poorly understood. Here, we provide data that demonstrate that B55ß, a regulatory subunit of protein phosphatase 2A, represents a molecular link between cytokine concentration and apoptosis in activated CD8+ T cells. Through the modulation of AKT, B55ß induced the expression of the proapoptotic molecule Hrk in response to cytokine withdrawal. Accordingly, B55ß and Hrk were both required for in vivo and in vitro contraction of activated CD8+ lymphocytes. We show that this process plays a role during clonal contraction, establishment of immune memory, and preservation of peripheral tolerance. This regulatory pathway may represent an unexplored opportunity to end unwanted immune responses or to promote immune memory.

Cancer immunosurveillance by CD8 T cells.

Clinical success attained in patients with cancer treated with checkpoint inhibitors has renewed the interest in the immune system and in particular in T cells as a therapeutic tool to eliminate tumors. Here, we discuss recent studies that evaluate the anti-tumor role of CD8 T cells and the mechanisms that interfere with this function. In particular, we review recent literature that has reported on the phenotype and transcriptome of tumor-infiltrating CD8 T cells and deciphered the mechanisms associated with failed tumor rejection.

The helminth-derived peptide GK-1 induces an anti-tumoral CD8 T cell response associated with downregulation of the PD-1/PD-L1 pathway.

CD8 T cells can kill malignant cells in an antigen-specific manner. However, anti-tumoral responses are usually limited by suppressive factors that curb the effector responses of tumor-infiltrating CD8 T cells. Therapeutic strategies to overcome intra-tumoral T cell suppression, for example immune checkpoint inhibition, have been clinically effective in patients with cancer. Here, we provide data that demonstrates that GK-1, a peptide derived from the parasite Taenia crassiceps, promotes an anti-melanoma CD8 T cell response with heightened effector characteristics that leads to an increased amount of tumor-infiltrating CD44+ IFN-γ-producing CD8 T cells. The response induced by GK-1 was associated with a reduction in the expression of PD-1 and PD-L1 on tumor-infiltrating CD8 and dendritic cells, respectively, effects that led to a dramatic decrease in tumor burden. Our results suggest that the immunomodulatory properties of GK-1 may promote a CD8 T cell response that may be therapeutically useful in the setting of cancer.

Expression of PD-1/PD-L1 and PD-L2 in peripheral T-cells from non-small cell lung cancer patients.

Binding of programmed death-1 (PD-1) with its ligands (PD-L1/2) transmits a co-inhibitory signal in activated T-cells that promotes T-cell exhaustion, leading to tumor immune evasion. The efficacy of antibodies targeting PD-1 and PD-L1 has led to a paradigm shift in lung cancer treatment but the prognostic and predictive value of tumor PD-L1 expression remains controversial. Evaluating PD-1, PD-L1/2 expression in peripheral blood cells may serve as a potential biomarker for prognosis and response to therapy. In this prospective observational study, plasma cytokine levels and PD-1, PD-L1 and PD-L2 expression was evaluated in circulating CD3+, CD3+CD4+ and CD3+CD8+ cells from 70 treatment-naïve patients with advanced NSCLC (Stage IIIB and IV) and from 10 healthy donors. The primary objective was to assess OS according to PD-1, PD-L1, PD-L2 expression status on PBMCs and lymphocyte subsets. Our results indicate that the percentage of PD-L1+CD3+, PD-L1+CD3+CD8+ PD-L2+PBMCs, PD-L2+CD3+, PD-L2+CD3+CD4+ cells was higher in patients than in healthy donors. Survival was decreased among patients with a high percentage of either PD-1+PBMCs, PD-1+CD3+, PD-L1+CD3+, PD-L1+CD3+CD8+, PD-L2+CD3+, PD-L2+CD3+CD4+, or PD-L2+CD3+CD8+ cells. IL-2 and TNF-α showed the strongest association with PD-L1 and PD-L2 expression on specific subsets of T-lymphocytes. Our findings suggest that increased PD-1/PD-L1/PDL-2 expression in PBMCs, particularly in T-cells, may be an additional mechanism leading to tumor escape from immune control. This study is registered with ClinicalTrials.gov, number NCT02758314.

CD47 overexpression is associated with decreased neutrophil apoptosis/phagocytosis and poor prognosis in non-small-cell lung cancer patients.

BACKGROUND: Non-small-cell lung cancer (NSCLC) patients often exhibit neutrophilia, which has been associated with poor clinical outcomes. However, the mechanisms that lead to neutrophilia have not been fully established. CD47 is an antiphagocytic molecule that promotes neutrophil recruitment. METHODS: Blood was collected from 50 treatment-naive patients with advanced NSCLC and from 25 healthy subjects. The frequency of CD66b+ cells and the expression of CD47 were determined by flow cytometry. Neutrophil apoptosis was determined by 7-amino-actinomycin D/Annexin V-APC staining. Phagocytosis was assessed by flow cytometry. Reactive oxygen species production after phorbol 12-myristate 13-acetate treatment was quantified by 2',7'-dichlorofluorescein fluorescence. Pro-inflammatory plasma cytokines were quantified using a cytometric bead array assay. RESULTS: The percentage of circulating neutrophils was significantly higher in patients than in controls (P<0.001). Patient-derived neutrophils had a higher oxidative potential than those of controls (P=0.0286). The number of neutrophils in late apoptosis/necrosis was lower in patients than in controls (P=0.0317). Caspase 3/7 activation was also lower in patients than in controls (P=0.0079). CD47 expression in whole-blood samples and in the neutrophil fraction was higher in NSCLC patients than in controls (P=0.0408 and P<0.001). Patient-derived neutrophils were phagocytosed at a lower rate than those of controls (P=0.0445). CD47 expression in neutrophils negatively correlated with their ingestion by macrophages (P=0.0039). High CD47 expression was associated with a lower overall survival. CONCLUSIONS: Increased CD47 expression on the surface of neutrophils was associated with a delay in neutrophil apoptosis and with an impairment in their phagocytic clearance by macrophages, suggesting that CD47 overexpression may be one of the underlying mechanisms leading to neutrophilia in NSCLC patients.

Phosphatase PP2A is requisite for the function of regulatory T cells.

Homeostasis of the immune system depends on the proper function of regulatory T cells (T(reg) cells). Compromised suppressive activity of T(reg) cells leads to autoimmune disease and graft rejection and promotes anti-tumor immunity. Here we report a previously unrecognized requirement for the serine-threonine phosphatase PP2A in the function of T(reg) cells. T(reg) cells exhibited high PP2A activity, and T(reg) cell-specific ablation of the PP2A complex resulted in a severe, multi-organ, lymphoproliferative autoimmune disorder. Mass spectrometry revealed that PP2A associated with components of the mTOR metabolic-checkpoint kinase pathway and suppressed the activity of the mTORC1 complex. In the absence of PP2A, T(reg) cells altered their metabolic and cytokine profile and were unable to suppress effector immune responses. Therefore, PP2A is required for the function of T(reg) cells and the prevention of autoimmunity.

CaMK4-dependent activation of AKT/mTOR and CREM-α underlies autoimmunity-associated Th17 imbalance.

Tissue inflammation in several autoimmune diseases, including SLE and MS, has been linked to an imbalance of IL-17-producing Th (Th17) cells and Tregs; however, the factors that promote Th17-driven autoimmunity are unclear. Here, we present evidence that the calcium/calmodulin-dependent protein kinase IV (CaMK4) is increased and required during Th17 cell differentiation. Isolation of naive T cells from a murine model of lupus revealed increased levels of CaMK4 following stimulation with Th17-inducing cytokines but not following Treg, Th1, or Th2 induction. Furthermore, naive T cells from mice lacking CaMK4 did not produce IL-17. Genetic or pharmacologic inhibition of CaMK4 decreased the frequency of IL-17-producing T cells and ameliorated EAE and lupus-like disease in murine models. Inhibition of CaMK4 reduced Il17 transcription through decreased activation of the cAMP response element modulator α (CREM-α) and reduced activation of the AKT/mTOR pathway, which is known to enhance Th17 differentiation. Importantly, silencing CaMK4 in T cells from patients with SLE and healthy individuals inhibited Th17 differentiation through reduction of IL17A and IL17F mRNA. Collectively, our results suggest that CaMK4 inhibition has potential as a therapeutic strategy for Th17-driven autoimmune diseases.

cAMP-responsive element modulator α (CREMα) trans-represses the transmembrane glycoprotein CD8 and contributes to the generation of CD3+CD4-CD8- T cells in health and disease.

T cell receptor-αß(+) CD3(+)CD4(-)CD8(-) "double-negative" T cells are expanded in the peripheral blood of patients with systemic lupus erythematosus and autoimmune lymphoproliferative syndrome. In both disorders, double-negative T cells infiltrate tissues, induce immunoglobulin production, and secrete proinflammatory cytokines. Double-negative T cells derive from CD8(+) T cells through down-regulation of CD8 surface co-receptors. However, the molecular mechanisms orchestrating this process remain unclear. Here, we demonstrate that the transcription factor cAMP-responsive element modulator α (CREMα), which is expressed at increased levels in T cells from systemic lupus erythematosus patients, contributes to transcriptional silencing of CD8A and CD8B. We provide the first evidence that CREMα trans-represses a regulatory element 5' of the CD8B gene. Therefore, CREMα represents a promising candidate in the search for biomarkers and treatment options in diseases in which double-negative T cells contribute to the pathogenesis.

Phenotype and function of dendritic cells of patients with systemic lupus erythematosus.

Dendritic cells (DC) regulate the activation and differentiation of T cells. They are activated by signals of inflammation and tissue damage, and thus could play a role in the amplification and perpetuation of autoimmune diseases such as systemic lupus erythematosus (SLE). Here we analyzed the phenotype of circulating DC from patients with SLE and studied their differentiation from monocytes. Peripheral blood DC exhibited increased levels of activation in patients with SLE. Although their in vitro differentiation process occurred normally, their responses to activation stimuli (LPS, TNF-α plus PGE(2), anti-CD40) were abnormal when compared to DC differentiated from healthy monocytes. When incubated in the presence of IL-10, DC from patients with SLE were able to induce tolerance to allogeneic antigens in a normal manner. Our results suggest that DC from patients with SLE are abnormal, in part due to the effect of abundant pro-inflammatory signals, but also because of intrinsic cellular defects that alter their responses to activation stimuli.

Neurocysticercosis: local and systemic immune-inflammatory features related to severity.

Neurocysticercosis (NC) is caused by the establishment of Taenia solium cysticerci in the central nervous system. Previous studies have established that neuroinflammation plays a key role in the severity of the disease. However, the relationship between peripheral and local immune response remains inconclusive. This work studies the peripheral and local immune-inflammatory features and their relationships, toward the identification of potential peripheral immunologic features related to severity. A panel of cytokines was measured in paired cerebrospinal fluid (CSF) and in the supernatant of antigen-specific stimulated peripheral blood mononuclear cells samples (SN) in a total of 31 untreated inflammatory and non-inflammatory NC patients. Increased clinical and radiologic severity was associated with an increased cerebrospinal fluid cell count. A peripheral proliferative depression that negatively correlates with CSF cellularity and TNFα and that positively correlates with SN IL5 was observed in severe NC patients. These results provide evidences to support the systemic proliferative response as a biomarker to monitor the level of neuroinflammation, of possible value in the patients' follow-up during treatment.

Suppression of autoimmunity and organ pathology in lupus-prone mice upon inhibition of calcium/calmodulin-dependent protein kinase type IV.

OBJECTIVE: Systemic lupus erythematosus (SLE) is a chronic inflammatory disease associated with aberrant immune cell function. Treatment involves the use of indiscriminate immunosuppression, which results in significant side effects. SLE T cells express high levels of calcium/calmodulin-dependent protein kinase type IV (CaMKIV), which translocates to the nucleus upon engagement of the T cell receptor-CD3 complex and accounts for abnormal T cell function. The purpose of this study was to determine whether inhibition of CaMKIV would improve disease pathology. METHODS: We treated MRL/lpr mice with KN-93, a CaMKIV inhibitor, starting at week 8 or week 12 of age and continuing through week 16 and evaluated skin lesions, proteinuria, kidney histopathology, proinflammatory cytokine production, and costimulatory molecule expression. We also determined the effect of silencing of CAMK4 on interferon-γ (IFNγ) expression by human SLE T cells. RESULTS: CaMKIV inhibition in MRL/lpr mice resulted in significant suppression of nephritis and skin disease, decreased expression of the costimulatory molecules CD86 and CD80 on B cells, and suppression of IFNγ and tumor necrosis factor α production. In human SLE T cells, silencing of CAMK4 resulted in suppression of IFNγ production. CONCLUSION: We conclude that suppression of CaMKIV mitigates disease development in lupus-prone mice by suppressing cytokine production and costimulatory molecule expression. Specific silencing of CAMK4 in human T cells results in similar suppression of IFNγ production. Our data justify the development of small-molecule CaMKIV inhibitors for the treatment of patients with SLE.

Pathogenesis of human systemic lupus erythematosus: recent advances.

Systemic lupus erythematosus (SLE) is an autoimmune disease with manifestations derived from the involvement of multiple organs including the kidneys, joints, nervous system and hematopoietic organs. Immune system aberrations, as well as heritable, hormonal and environmental factors interplay in the expression of organ damage. Recent contributions from different fields have developed our understanding of SLE and reshaped current pathogenic models. Here, we review recent findings that deal with (i) genes associated with disease expression; (ii) immune cell molecular abnormalities that lead to autoimmune pathology; (iii) the role of hormones and sex chromosomes in the development of disease; and (iv) environmental and epigenetic factors thought to contribute to the expression of SLE. Finally, we highlight molecular defects intimately associated with the disease process of SLE that might represent ideal therapeutic targets and disease biomarkers.

B cells contribute to ischemia/reperfusion-mediated tissue injury.

Multiple elements are known to participate in ischemia/reperfusion (I/R)-mediated tissue injury. Amongst them, B cells have been shown to contribute by the production of antibodies that bind to ischemic cells and fix complement. It is currently unknown whether B cells participate through antibody-independent mechanisms in the pathogenesis of I/R. In a mesenteric I/R model we found that B cells infiltrate the injured intestine of normal and autoimmune mice 2h after reperfusion is established. B cell depletion protected mice from the development of I/R-mediated intestinal damage. The protection conferred by B cell depletion was significantly greater in MRL/lpr mice. Finally, we show that ischemic tissue expressed the B cell-attractant CXCL13 and infiltrating B cells expressed the corresponding receptor CXCR5. Our data grant B cells an antibody-independent role in the pathogenesis of intestinal I/R and suggest that B cells accumulate in the injured tissue in response to the chemokine CXCL13.

T cells and in situ cryoglobulin deposition in the pathogenesis of lupus nephritis.

We discuss a 53-year-old woman with systemic lupus erythematosus who presented with vasculitis, hypocomplementemia and nephritis. Although her serum complement 4 (C4) levels were zero, she had four copies of C4 gene. Renal biopsy revealed membranoproliferative glomerulonephritis and the presence of cryoglobulins, detected by electron microscopy, and significant numbers of T cells in the interstitium. Cryoglobulins were considered responsible for the complete consumption of C4 in the serum the levels of which improved gradually after treatment. T cells in the kidney were found to express CD44 and phosphorylated ezrin/radixin/moiesin which explain why they homed to the kidney inappropriately. The contribution of cryoglobulins and T cells in the expression of kidney pathology is discussed.

Adult-onset Still disease as the cause of fever of unknown origin.

We conducted the current study to evaluate the cases of fever of unknown origin (FUO) admitted in our institution during the 10 years between 1991 and 2001 and to compare the patients diagnosed as having adult-onset Still disease (AOSD) with the patients with FUO due to other diagnoses. We performed a case-control study and analyzed 26 patients with AOSD and 135 patients with FUO due to other diseases. Controls were classified into 1 of 4 groups: 1. Infectious diseases; 2. Malignant conditions; 3. Autoimmune diseases; 4. No diagnosis. Differences between groups were evaluated by analysis of variance (ANOVA). Odds ratios (OR) were calculated by multiple logistic regression analyses. Patients with AOSD were younger than controls. Arthritis (OR, 8.6; 95% confidence interval [CI], 1.5-49.1; p = 0.014), pharyngitis (OR, 6.9; 95% CI, 1.5-30.2; p = 0.010), splenomegaly (OR, 5.4; 95% CI, 1.1-26.7; p = 0.039), and neutrophilic leukocytosis (OR, 18.1; 95% CI, 3.5-93.6; p = 0.001) were significantly more common in patients with AOSD than in the control groups. A clinical scale that identifies patients with AOSD was designed. It proved to be highly specific ( approximately 98%), with predictive values greater than 90%.AOSD is a defined clinical entity. In most cases, it is clinically distinguishable from other causes of FUO. We propose a clinical scale as a tool to identify patients whose disease can be diagnosed based on clinical grounds without the need of long, costly diagnostic procedures.

IL-10 production in B cells is confined to CD154+ cells in patients with systemic lupus erythematosus.

The immunological hallmark of SLE is B cell hyperactivity. CD154 (CD40-L) is normally expressed in activated T cells, and plays an important role in T-B interactions. Its expression is increased in SLE T cells. Additionally, its expression on B cells leads to the development of SLE-like disease in a transgenic model. IL-10 is a key cytokine in the disturbed SLE immune system. The aim of this work was to explore the relation between IL-10 and CD154 expression in SLE B cells. We studied 11 SLE patients and 10 healthy volunteers. Mononuclear cells were isolated from peripheral blood and cultured in the presence or absence of Cowan I Strain Staphylococcus (CSS). Surface CD154 and intracytoplasmic IL-10 expression were quantified with flow cytometry. In basal conditions, CD154 expression was not different in patients and controls. B cell stimulation did not cause a significant increase in CD154 expression in control B cells. However, its expression increased 2 times in B cells obtained from SLE patients. IL-10 expression was confined to CD154(+) cells. Our results show that IL-10 production is intimately linked to CD154 expression in B cells, and that the IL-10(+)CD154(+) B cell subset increases abnormally when SLE-derived cells are stimulated with CSS.