Atorvastatin restores Lck expression and lipid raft-associated signaling in T cells from patients with systemic lupus erythematosus

Dysregulated lipid metabolism networks modulate T-cell function in people with relapsing-remitting multiple sclerosis

Altered cholesterol, oxysterol, sphingolipid, and fatty acid concentrations are reported in blood, cerebrospinal fluid, and brain tissue of people with relapsing-remitting multiple sclerosis (RRMS) and are linked to disease progression and treatment responses. CD4 + T cells are pathogenic in RRMS, and defective T-cell function could be mediated in part by liver X receptors (LXRs)-nuclear receptors that regulate lipid homeostasis and immunity. RNA-sequencing and pathway analysis identified that genes within the 'lipid metabolism' and 'signalling of nuclear receptors' pathways were dysregulated in CD4 + T cells isolated from RRMS patients compared with healthy donors. While LXRB and genes associated with cholesterol metabolism were upregulated, other T-cell LXR-target genes, including genes involved in cellular lipid uptake (inducible degrader of the LDL receptor, IDOL), and the rate-limiting enzyme for glycosphingolipid biosynthesis (UDP-glucosylceramide synthase, UGCG) were downregulated in T cells from patients with RRMS compared to healthy donors. Correspondingly, plasma membrane glycosphingolipids were reduced, and cholesterol levels increased in RRMS CD4 + T cells, an effect partially recapitulated in healthy T cells by in vitro culture with T-cell receptor stimulation in the presence of serum from RRMS patients. Notably, stimulation with LXR-agonist GW3965 normalized membrane cholesterol levels, and reduced proliferation and IL17 cytokine production in RRMS CD4 + T-cells. Thus, LXR-mediated lipid metabolism pathways were dysregulated in T cells from patients with RRMS and could contribute to RRMS pathogenesis. Therapies that modify lipid metabolism could help restore immune cell function.

B- and T-Lymphocyte Attenuator in Systemic Lupus Erythematosus Disease Pathogenesis

B- and T-lymphocyte attenuator (BTLA; CD272) is an immunoglobulin superfamily member and part of a family of checkpoint inhibitory receptors that negatively regulate immune cell activation. The natural ligand for BTLA is herpes virus entry mediator (HVEM; TNFRSF14), and binding of HVEM to BTLA leads to attenuation of lymphocyte activation. In this study, we evaluated the role of BTLA and HVEM expression in the pathogenesis of systemic lupus erythematosus (SLE), a multisystem autoimmune disease. Peripheral blood mononuclear cells from healthy volunteers (N = 7) were evaluated by mass cytometry by time-of-flight to establish baseline expression of BTLA and HVEM on human lymphocytes compared with patients with SLE during a self-reported flare (N = 5). High levels of BTLA protein were observed on B cells, CD4+, and CD8+ T cells, and plasmacytoid dendritic cells in healthy participants. HVEM protein levels were lower in patients with SLE compared with healthy participants, while BTLA levels were similar between SLE and healthy groups. Correlations of BTLA-HVEM hub genes' expression with patient and disease characteristics were also analyzed using whole blood gene expression data from patients with SLE (N = 1,760) and compared with healthy participants (N = 60). HVEM, being one of the SLE-associated genes, showed an exceptionally strong negative association with disease activity. Several other genes in the BTLA-HVEM signaling network were strongly (negative or positive) correlated, while BTLA had a low association with disease activity. Collectively, these data provide a clinical rationale for targeting BTLA with an agonist in SLE patients with low HVEM expression.

Autoimmune diseases and atherosclerotic cardiovascular disease

Autoimmune diseases are associated with a dramatically increased risk of atherosclerotic cardiovascular disease and its clinical manifestations. The increased risk is consistent with the notion that atherogenesis is modulated by both protective and disease-promoting immune mechanisms. Notably, traditional cardiovascular risk factors such as dyslipidaemia and hypertension alone do not explain the increased risk of cardiovascular disease associated with autoimmune diseases. Several mechanisms have been implicated in mediating the autoimmunity-associated cardiovascular risk, either directly or by modulating the effect of other risk factors in a complex interplay. Aberrant leukocyte function and pro-inflammatory cytokines are central to both disease entities, resulting in vascular dysfunction, impaired resolution of inflammation and promotion of chronic inflammation. Similarly, loss of tolerance to self-antigens and the generation of autoantibodies are key features of autoimmunity but are also implicated in the maladaptive inflammatory response during atherosclerotic cardiovascular disease. Therefore, immunomodulatory therapies are potential efficacious interventions to directly reduce the risk of cardiovascular disease, and biomarkers of autoimmune disease activity could be relevant tools to stratify patients with autoimmunity according to their cardiovascular risk. In this Review, we discuss the pathophysiological aspects of the increased cardiovascular risk associated with autoimmunity and highlight the many open questions that need to be answered to develop novel therapies that specifically address this unmet clinical need.

Dysregulated serum lipid profile is associated with inflammation and disease activity in primary Sjögren's syndrome: a retrospective study in China

PURPOSE

To investigate the relationship between the lipid profiles of patients with primary Sjögren's syndrome (pSS) and other clinical characteristics, laboratory examination, disease activity, and inflammatory factors. In addition, the risk factors for hyperlipidemia-related complications of pSS and the effect of hydroxychloroquine (HCQ) usage on the lipid profile were incorporated into this study.

METHODS

This is a single-center, retrospective study that included 367 patients who were diagnosed with pSS at Tongji Hospital, School of Medicine, Tongji University, China from January 2010 to March 2022. Initially, demographic information, clinical characteristics, medication records, and complications of the patients were gathered. A case-control analysis compared the 12 systems involvement (ESSDAI domain), clinical symptoms, and laboratory tests between pSS patients with and without dyslipidemia. A simple linear regression model was employed to investigate the relationship between serum lipid profile and inflammatory factors. Logistics regression analysis was performed to assess variables for hyperlipidemia-related complications of pSS. The paired t-test was then used to evaluate the improvement in lipid profile among pSS patients.

RESULTS

48.7 % of all pSS patients had dyslipidemia, and alterations in lipid levels were related to gender, age, and smoking status but not body mass index (BMI). Dyslipidemia is more prevalent in pSS patients who exhibit heightened autoimmunity and elevated levels of inflammation. Higher concentrations of multiple highly inflammatory factors correlate with a more severe form of dyslipidemia. Non-traditional cardiovascular risk factors may contribute to hyperlipidemia-related complications of pSS, such as increased, low complement 3 (C3) and low C4. According to our study, HCQ usage may protect against lipid-related disease in pSS.

CONCLUSION

Attention should be paid to the dyslipidemia of pSS. This research aims to clarify the population portrait of pSS patients with abnormal lipid profiles and provides insights into the correlation between metabolism and inflammation in individuals with pSS and the potential role they play in the advancement of the disease. These findings provide novel avenues for further understanding the underlying mechanisms of pSS pathogenesis.

The life of the cell membrane: A paradigmatic reading from Deleuze and Guattari

While the Fluid Mosaic model (FMM) is widely accepted as an account of the cell membrane's structure-function, its inability to explain certain phenomena has led to the lipid rafts hypothesis (nanodomains) that spontaneous spatiotemporal enriched zones of sphingolipids-cholesterol-protein exist within the membrane. In this text, we propose a novel approach that conceives the cell membrane as a living entity. The questions regarding the FMM revolve around the fact that, although these molecular components are present in many cell types, the membrane does not react in the same way to every external agent; for example, a virus evokes a particular response: why is there some marked specificity of virus (or toxin) attack on one (or some) of these cell types and not to other cell types that nevertheless have a similar membrane protein constitution? The crucial question, to explain this selectivity, would be what determines the specificity of attack on some cells and not others? While FMN assumes a dynamism between macrostates at the intramolecular, intermolecular, and/or collective levels in the membrane, the approach of the lipid raft model presupposes a much greater and more complex dynamics of microstates (even nano-states) of these molecular components. In other words, it implies higher and instantaneous mobility as assemblages ("intentional") and thus, of the membrane itself (as a collective), in response to changes in the internal and external physicochemical environment over a broad spatiotemporal scale. This suggests a mechanism of membrane adaptation in the face of evolutionary constraints. In this text, we propose a paradigmatic approach, from Deleuze-Guattari's philosophy: to conceive the cell membrane as living and not as a mere molecular conglomerate with particular functions and mechanical processes between molecules. For this, we employ the functional concepts of territory and machinic assemblage, whence the vitality of the membrane would allow us to postulate instantaneous updates, within wider spatiotemporal scales in its composition in contrast with the model that dominates as a more plausible explanation nowadays, that does not include smaller spatiotemporal events. If we resort to the concept of territory and its different media components, we could offer a more plausible explanation of the vigorous dynamism in the composition of the cell membrane since it would allow more subtle and complex differentiations between media and thus make visible the constant and instant changes. We propose that the model of nanodomains, understood as a process of dynamic territorialization, offers a more complex and subtle explanation of the instantaneous changes in the cell membrane's composition. This approach expands the explanatory framework for cellular phenomena and reveals their spatiotemporal complexity in accordance with other research.

Decoding the crosstalk between mevalonate metabolism and T cell function

The mevalonate pathway is an essential metabolic pathway in T cells regulating development, proliferation, survival, differentiation, and effector functions. The mevalonate pathway is a complex, branched pathway composed of many enzymes that ultimately generate cholesterol and nonsterol isoprenoids. T cells must tightly control metabolic flux through the branches of the mevalonate pathway to ensure sufficient isoprenoids and cholesterol are available to meet cellular demands. Unbalanced metabolite flux through the sterol or the nonsterol isoprenoid branch is metabolically inefficient and can have deleterious consequences for T cell fate and function. Accordingly, there is tight regulatory control over metabolic flux through the branches of this essential lipid synthetic pathway. In this review we provide an overview of how the branches of the mevalonate pathway are regulated in T cells and discuss our current understanding of the relationship between mevalonate metabolism, cholesterol homeostasis and T cell function.

New insights into the Lck-NF-κB signaling pathway

Lck is essential for the development, activity, and proliferation of T cells, which may contribute to pathological progression and development of human diseases, such as autoimmune disorders and cancers when functioning aberrantly. Nuclear factor-κB (NF-κB) was initially discovered as a factor bound to the κ light-chain immunoglobulin enhancer in the nuclei of activated B lymphocytes. Activation of the nuclear factor-κB pathway controls expression of several genes that are related to cell survival, apoptosis, and inflammation. Abnormal expression of Lck and nuclear factor-κB has been found in autoimmune diseases and malignancies, including rheumatoid arthritis, systemic lupus erythematosus, acute T cell lymphocytic leukemia, and human chronic lymphocytic leukemia, etc. Nuclear factor-κB inhibition is effective against autoimmune diseases and malignancies through blocking inflammatory responses, although it may lead to serious adverse reactions that are unexpected and unwanted. Further investigation of the biochemical and functional interactions between nuclear factor-κB and other signaling pathways may be helpful to prevent side-effects. This review aims to clarify the Lck-nuclear factor-κB signaling pathway, and provide a basis for identification of new targets and therapeutic approaches against autoimmune diseases and malignancies.

Hypercholesterolemia promotes autoantibody production and a lupus-like pathology via decreased DNase-mediated clearance of DNA

Hypercholesterolemia exacerbates autoimmune response and accelerates the progression of several autoimmune disorders, but the mechanistic basis is not well understood. We recently demonstrated that hypercholesterolemia is associated with increased serum extracellular DNA levels secondary to a defect in DNase-mediated clearance of DNA. In this study, we tested whether the impaired DNase response plays a causal role in enhancing anti-nuclear antibody levels and renal immune complex deposition in an Apoe^-/- mouse model of hypercholesterolemia. We demonstrate that hypercholesterolemic mice have enhanced anti-ds-DNA and anti-nucleosome antibody levels which is associated with increased immune complex deposition in the renal glomerulus. Importantly, treatment with DNase1 led to a decrease in both the autoantibody levels as well as renal pathology. Additionally, we show that humans with hypercholesterolemia have decreased systemic DNase activity and increased anti-nuclear antibodies. In this context, our data suggest that recombinant DNase1 may be an attractive therapeutic strategy to lower autoimmune response and disease progression in patients with autoimmune disorders associated with concomitant hypercholesterolemia.

Sex-Specific Associations Between Serum Lipids, Antinuclear Antibodies, and Statin Use in National Health and Nutrition Examination Surveys 1999-2004

Lipid metabolism contributes to the regulation of leukocyte activity and immune responses, and may serve as a therapeutic target in the pathophysiology and clinical management of autoimmune disorders. In addition to lipid-lowering properties, statins have been shown to exert anti-inflammatory and immunomodulatory effects within the context of autoimmunity. Importantly, autoimmune incidence and lipid markers differ between men and women, suggesting that the relationship between lipid metabolism and immune function may vary by sex. Therefore, we investigated whether a predictive, sex-specific relationship exists between serum lipids, statin use, and antinuclear antibodies (ANA)—a routine clinical marker of autoimmunity and immune dysfunction—in U.S. men and women (>20 years old; n = 1,526) from the National Health and Nutrition Examination Survey (NHANES) 1999–2004. Within this population, a greater proportion of women were positive for ANA (ANA+) and had higher ANA titers, as compared to men. While we did not observe statistical differences in average total cholesterol, LDL-cholesterol (LDL-C), HDL-cholesterol (HDL-C), or triglyceride levels in ANA positive (ANA+) vs. ANA negative (ANA–) men or women, we observed that a greater proportion of ANA+ women had high total cholesterol levels (>240 mg/dL) when compared to ANA+ men (13.0 vs. 9.0%), and that a greater percentage of ANA+ women had low HDL-C as compared to ANA+ men (29.2 vs. 19.6%). However, in logistic regression models, total cholesterol, LDL-C, and HDL-C levels were not able to predict ANA status, whereas elevated serum triglycerides (150 to < 200 mg/dL) were significantly less likely to be ANA+ vs. ANA– (OR 0.33; 95% CI 0.11–0.92) in men only. Interestingly, women who reported taking statins have significantly lower odds of being ANA+ (OR 0.25; 95% CI 0.09–0.76), whereas no significant association between statin use and ANA status was observed in men. Together, our findings provide novel insight into the relationship between lipid metabolism and autoimmunity by elucidating the limited, albeit sex-specific utility of routine clinical serum lipid levels to predict ANA status at the population level, while further identifying a sex-specific and protective role for statins in predicting ANA status in women.

A Deep Insight Into Regulatory T Cell Metabolism in Renal Disease: Facts and Perspectives

Kidney disease encompasses a complex set of diseases that can aggravate or start systemic pathophysiological processes through their complex metabolic mechanisms and effects on body homoeostasis. The prevalence of kidney disease has increased dramatically over the last two decades. CD4⁺CD25⁺ regulatory T (Treg) cells that express the transcription factor forkhead box protein 3 (Foxp3) are critical for maintaining immune homeostasis and preventing autoimmune disease and tissue damage caused by excessive or unnecessary immune activation, including autoimmune kidney diseases. Recent studies have highlighted the critical role of metabolic reprogramming in controlling the plasticity, stability, and function of Treg cells. They are also likely to play a vital role in limiting kidney transplant rejection and potentially promoting transplant tolerance. Metabolic pathways, such as mitochondrial function, glycolysis, lipid synthesis, glutaminolysis, and mammalian target of rapamycin (mTOR) activation, are involved in the development of renal diseases by modulating the function and proliferation of Treg cells. Targeting metabolic pathways to alter Treg cells can offer a promising method for renal disease therapy. In this review, we provide a new perspective on the role of Treg cell metabolism in renal diseases by presenting the renal microenvironment、relevant metabolites of Treg cell metabolism, and the role of Treg cell metabolism in various kidney diseases.

Lipid Metabolism: Immune Regulation and Therapeutic Prospectives in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a heterogeneous disease characterized by the production of abnormal autoantibodies and immune complexes that can affect the organ and organ systems, particularly the kidneys and the cardiovascular system. Emerging evidence suggests that dysregulated lipid metabolism, especially in key effector cells, such as T cells, B cells, and innate immune cells, exerts complex effects on the pathogenesis and progression of SLE. Beyond their important roles as membrane components and energy storage, different lipids can also modulate different cellular processes, such as proliferation, differentiation, and survival. In this review, we summarize altered lipid metabolism and the associated mechanisms involved in the pathogenesis and progression of SLE. Furthermore, we discuss the recent progress in the role of lipid metabolism as a potential therapeutic target in SLE.

The Role of Immunometabolism in the Pathogenesis of Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder in which pathogenic abnormalities within both the innate and adaptive immune response have been described. In order to activated, proliferate and maintain this immunological response a drastic upregulation in energy metabolism is required. Recently, a greater understanding of these changes in cellular bioenergetics have provided new insight into the links between immune response and the pathogenesis of a number of diseases, ranging from cancer to diabetes and multiple sclerosis. In this review, we highlight the latest understanding of the role of immunometabolism in SLE with particular focus on the role of abnormal mitochondrial function, lipid metabolism, and mTOR signaling in the immunological phenomenon observed in the SLE. We also consider what implications this has for future therapeutic options in the management of the disease in future.

Lipid metabolism in autoimmune rheumatic disease: implications for modern and conventional therapies

Suppressing inflammation has been the primary focus of therapies in autoimmune rheumatic diseases (AIRDs), including rheumatoid arthritis and systemic lupus erythematosus. However, conventional therapies with low target specificity can have effects on cell metabolism that are less predictable. A key example is lipid metabolism; current therapies can improve or exacerbate dyslipidemia. Many conventional drugs also require in vivo metabolism for their conversion into therapeutically beneficial products; however, drug metabolism often involves the additional formation of toxic by-products, and rates of drug metabolism can be heterogeneous between patients. New therapeutic technologies and research have highlighted alternative metabolic pathways that can be more specifically targeted to reduce inflammation but also to prevent undesirable off-target metabolic consequences of conventional antiinflammatory therapies. This Review highlights the role of lipid metabolism in inflammation and in the mechanisms of action of AIRD therapeutics. Opportunities for cotherapies targeting lipid metabolism that could reduce immunometabolic complications and potential increased cardiovascular disease risk in patients with AIRDs are discussed.

Metabolomics Defines Complex Patterns of Dyslipidaemia in Juvenile-SLE Patients Associated with Inflammation and Potential Cardiovascular Disease Risk

Cardiovascular disease (CVD) is a leading cause of mortality in patients with juvenile-onset systemic lupus erythematosus (JSLE) associated with atherosclerosis. The interplay between dyslipidaemia and inflammation—mechanisms that drive atherosclerosis—were investigated retrospectively in adolescent JSLE patients using lipoprotein-based serum metabolomics in patients with active and inactive disease, compared to healthy controls (HCs). Data was analysed using machine learning, logistic regression, and linear regression. Dyslipidaemia in JSLE patients was characterised by lower levels of small atheroprotective high-density lipoprotein subsets compared to HCs. These changes were exacerbated by active disease and additionally associated with significantly higher atherogenic very-low-density lipoproteins (VLDL) compared to patients with low disease activity. Atherogenic lipoprotein subset expression correlated positively with clinical and serological markers of JSLE disease activity/inflammation and was associated with disturbed liver function, and elevated expression of T-cell and B-cell lipid rafts (cell signalling platforms mediating immune cell activation). Finally, exposing VLDL/LDL from patients with active disease to HC lymphocytes induced a significant increase in lymphocyte lipid raft activation compared to VLDL/LDL from inactive patients. Thus, metabolomic analysis identified complex patterns of atherogenic dyslipidaemia in JSLE patients associated with inflammation. This could inform lipid-targeted therapies in JSLE to improve cardiovascular outcomes.

Cardiovascular Disease in Patients With Systemic Lupus Erythematosus: Potential for Improved Primary Prevention With Statins

Cardiovascular disease (CVD) is a significant cause of morbidity and mortality in patients with systemic lupus erythematosus (SLE). This is especially true in SLE patients with traditional CVD risk factors (eg, hypertension, hyperlipidemia, obesity) and disease-related risk factors (eg, increased SLE disease activity, elevated C-reactive protein levels, and antiphospholipid antibodies). The only guidelines in the primary prevention of CVD in SLE patients involve reducing traditional risk factors, but there are additional therapies that may be beneficial, including statin use. Current data on statin use for prevention of CVD in SLE patients are limited, but there have been some promising results. Statin use has been shown to be especially important in SLE patients for decreasing low-density lipoprotein levels and preventing CVD in hyperlipidemic patients. In addition, there is evidence suggesting that it may be beneficial to use statins in SLE patients with chronically elevated high-sensitivity C-reactive protein levels and antiphospholipid antibodies. It is important to continue to investigate the impact of statins on CVD in SLE patients, as they could significantly improve outcomes in patients with this disease.

HDL and persistent inflammation immunosuppression and catabolism syndrome

PURPOSE OF REVIEW

This study reviews the mechanisms of HDL cholesterol immunomodulation in the context of the mechanisms of chronic inflammation and immunosuppression causing persistent inflammation, immunosuppression and catabolism syndrome (PICS) and describes potential therapies and gaps in current research.

RECENT FINDINGS

Low HDL cholesterol is predictive of acute sepsis severity and outcome. Recent research has indicated apolipoprotein is a prognostic indicator of long-term outcomes. The pathobiologic mechanisms of PICS have been elucidated in the past several years. Recent research of the interaction of HDL pathways in related chronic inflammatory diseases may provide insights into further mechanisms and therapeutic targets.

SUMMARY

HDL significantly influences innate and adaptive immune pathways relating to chronic disease and inflammation. Further research is needed to better characterize these interactions in the setting of PICS.

Effects of Atorvastatin on T-Cell Activation and Apoptosis in Systemic Lupus Erythematosus and Novel Simulated Interactions With C-Reactive Protein and Interleukin 6

Objective

We study activation of T helper 17 (Th17) and regulatory T (Treg) cells and induction of apoptosis in cells from patients with systemic lupus erythematosus (SLE) compared with controls and effects of atorvastatin and its simulated interactions with other compounds.

Methods

Mononuclear cells from 10 patients with SLE and 10 controls were cultured in conditions that induce Th17 and/or Treg cell polarization and/or apoptosis and were studied by FACScan. Gene expression was determined by quantitative real‐time reverse transcription–polymerase chain reaction. Cytokines in plasma were determined by enzyme‐linked immunosorbent assay. The Search Tool for Interactions of Chemicals (STITCH) was used to retrieve information regarding the binding properties of atorvastatin.

Results

Among patients with SLE, the proportion of Th17 (CD4⁺IL17⁺) cells was higher compared with controls after activation, with Th17 or Treg polarizing cytokines, phorbol myristate acetate, and ionomycin. In contrast, Treg cells (CD4⁺CD25⁺CD127^dim/−) frequencies were lower. CD95 stimulation induced relatively more apoptosis in Treg cells and less in Th17 cells, as compared with controls. Addition of atorvastatin normalized Th17/Treg cell balance and apoptosis induction. Accordingly, the ratio of RORC/FoxP3 decreased in patients with SLE. Interleukin 17 and interleukin 6 (IL‐6) levels were increased in patients with SLE. Atorvastatin interacted strongly with C‐reactive protein (CRP) and also significantly with IL‐6.

Conclusion

There is a higher proportion of Th17 cells and a lower proportion of Treg cells in patients with SLE after activation. Th17 cells were more resistant than Treg cells to CD95‐induced apoptosis in SLE. Atorvastatin normalized these effects. Our findings reveal a novel mechanism behind the imbalance of Th17/Treg cells with implications for treatment in SLE. We determine for the first time simulated interaction between atorvastatin, CRP, and IL‐6, implying a novel role of atorvastatin.

Coronaviruses, cholesterol and statins: Involvement and application for Covid-19

The infectious power of coronaviruses is dependent on cholesterol present in the membranes of their target cells. Indeed, the virus enters the infected cell either by fusion or by endocytosis, in both cases involving cholesterol-enriched membrane microdomains. These membrane domains can be disorganized in-vitro by various cholesterol-altering agents, including statins that inhibit cell cholesterol biosynthesis. As a consequence, numerous cell physiology processes, such as signaling cascades, can be compromised. Also, some examples of anti-bacterial and anti-viral effects of statins have been observed for infectious agents known to be cholesterol dependent. In-vivo, besides their widely-reported hypocholesterolemic effect, statins display various pleiotropic effects mediated, at least partially, by perturbation of membrane microdomains as a consequence of the alteration of endogenous cholesterol synthesis. It should thus be worth considering a high, but clinically well-tolerated, dose of statin to treat Covid-19 patients, in the early phase of infection, to inhibit virus entry into the target cells, in order to control the viral charge and hence avoid severe clinical complications. Based on its efficacy and favorable biodisposition, an option would be considering Atorvastatin, but randomized controlled clinical trials are required to test this hypothesis. This new therapeutic proposal takes benefit from being a drug repurposing, applied to a widely-used drug presenting a high efficiency-to-toxicity ratio. Additionally, this therapeutic strategy avoids any risk of drug resistance by viral mutation since it is host-targeted. Noteworthy, the same pharmacological approach could also be proposed to address different animal coronavirus endemic infections that are responsible for heavy economic losses.

LXR directly regulates glycosphingolipid synthesis and affects human CD4+ T cell function

The liver X receptor (LXR) is a key transcriptional regulator of cholesterol, fatty acid, and phospholipid metabolism. Dynamic remodeling of immunometabolic pathways, including lipid metabolism, is a crucial step in T cell activation. Here, we explored the role of LXR-regulated metabolic processes in primary human CD4⁺ T cells and their role in controlling plasma membrane lipids (glycosphingolipids and cholesterol), which strongly influence T cell immune signaling and function. Crucially, we identified the glycosphingolipid biosynthesis enzyme glucosylceramide synthase as a direct transcriptional LXR target. LXR activation by agonist GW3965 or endogenous oxysterol ligands significantly altered the glycosphingolipid:cholesterol balance in the plasma membrane by increasing glycosphingolipid levels and reducing cholesterol. Consequently, LXR activation lowered plasma membrane lipid order (stability), and an LXR antagonist could block this effect. LXR stimulation also reduced lipid order at the immune synapse and accelerated activation of proximal T cell signaling molecules. Ultimately, LXR activation dampened proinflammatory T cell function. Finally, compared with responder T cells, regulatory T cells had a distinct pattern of LXR target gene expression corresponding to reduced lipid order. This suggests LXR-driven lipid metabolism could contribute to functional specialization of these T cell subsets. Overall, we report a mode of action for LXR in T cells involving the regulation of glycosphingolipid and cholesterol metabolism and demonstrate its relevance in modulating T cell function.

Lipid Metabolism Profiles in Rheumatic Diseases

Rheumatic diseases are a group of chronic autoimmune disorders that involve multiple organs or systems and have high mortality. The mechanisms of these diseases are still ill-defined, and targeted therapeutic strategies are still challenging for physicians. Recent research indicates that cell metabolism plays important roles in the pathogenesis of rheumatic diseases. In this review, we mainly focus on lipid metabolism profiles (dyslipidaemia, fatty acid metabolism) and mechanisms in rheumatic diseases and discuss potential clinical applications based on lipid metabolism profiles.

The Role of Protein and Lipid Clustering in Lymphocyte Activation

Lymphocytes must strike a delicate balance between activating in response to signals from potentially pathogenic organisms and avoiding activation from stimuli emanating from the body's own cells. For cells, such as T or B cells, maximizing the efficiency and fidelity, whilst minimizing the crosstalk, of complex signaling pathways is crucial. One way of achieving this control is by carefully orchestrating the spatiotemporal organization of signaling molecules, thereby regulating the rates of protein-protein interactions. This is particularly true at the plasma membrane where proximal signaling events take place and the phenomenon of protein microclustering has been extensively observed and characterized. This review will focus on what is known about the heterogeneous distribution of proteins and lipids at the cell surface, illustrating how such distributions can influence signaling in health and disease. We particularly focus on nanoscale molecular organization, which has recently become accessible for study through advances in microscope technology and analysis methodology.

Direct Regulation of the T Cell Antigen Receptor's Activity by Cholesterol

Biological membranes consist of hundreds of different lipids that together with the embedded transmembrane (TM) proteins organize themselves into small nanodomains. In addition to this function of lipids, TM regions of proteins bind to lipids in a very specific manner, but the function of these TM region-lipid interactions is mostly unknown. In this review, we focus on the role of plasma membrane cholesterol, which directly binds to the αβ T cell antigen receptor (TCR), and has at least two opposing functions in αβ TCR activation. On the one hand, cholesterol binding to the TM domain of the TCRβ subunit keeps the TCR in an inactive, non-signaling conformation by stabilizing this conformation. This assures that the αβ T cell remains quiescent in the absence of antigenic peptide-MHC (the TCR's ligand) and decreases the sensitivity of the T cell toward stimulation. On the other hand, cholesterol binding to TCRβ leads to an increased formation of TCR nanoclusters, increasing the avidity of the TCRs toward the antigen, thus increasing the sensitivity of the αβ T cell. In mouse models, pharmacological increase of the cholesterol concentration in T cells caused an increase in TCR clustering, and thereby enhanced anti-tumor responses. In contrast, the γδ TCR does not bind to cholesterol and might be regulated in a different manner. The goal of this review is to put these seemingly controversial findings on the impact of cholesterol on the αβ TCR into perspective.

Statins: Could an old friend help in the fight against COVID-19?

The COVID-19 pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has overwhelmed healthcare systems requiring the rapid development of treatments, at least, to reduce COVID-19 severity. Drug repurposing offers a fast track. Here, we discuss the potential beneficial effects of statins in COVID-19 patients based on evidence that they may target virus receptors, replication, degradation, and downstream responses in infected cells, addressing both basic research and epidemiological information. Briefly, statins could modulate virus entry, acting on the SARS-CoV-2 receptors, ACE2 and CD147, and/or lipid rafts engagement. Statins, by inducing autophagy activation, could regulate virus replication or degradation, exerting protective effects. The well-known anti-inflammatory properties of statins, by blocking several molecular mechanisms, including NF-κB and NLRP3 inflammasomes, could limit the "cytokine storm" in severe COVID-19 patients which is linked to fatal outcome. Finally, statin moderation of coagulation response activation may also contribute to improving COVID-19 outcomes. LINKED ARTICLES: This article is part of a themed issue on The Pharmacology of COVID-19. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.21/issuetoc.

Systemic Lupus Erythematosus (SLE) Therapy: The Old and the New

Despite recent improvements in the treatment of systemic lupus erythematosus (SLE), disease activity, comorbidities and drug toxicity significantly contribute to the risk of progressive irreversible damage accrual and increased mortality in patients with this chronic disease. Moreover, even lupus patients in remission often report residual symptoms, such as fatigue, which have a considerable impact on their health-related quality of life. In recent decades, SLE treatment has moved from the use of hydroxychloroquine, systemic glucocorticosteroids and conventional immunosuppressive drugs to biologic agents, of which belimumab is the first and only biologic agent approved for the treatment for SLE to date. Novel therapies targeting interferons, cytokines and their receptors, intracellular signals, plasma cells, T lymphocytes and co-stimulatory molecules are being evaluated. In the context of a holistic approach, growing evidence is emerging of the importance of correct lifestyle habits in the management of lupus manifestations and comorbidities. The aim of this paper is to provide an overview of current pharmacological and non-pharmacological treatment options and emerging therapies in SLE.

T Cell Metabolism: A New Perspective on Th17/Treg Cell Imbalance in Systemic Lupus Erythematosus

The Th17/T-regulatory (Treg) cell imbalance is involved in the occurrence and development of organ inflammation in systemic lupus erythematosus (SLE). Metabolic pathways can regulate T cell differentiation and function, thus contributing to SLE inflammation. Increasingly, data have shown metabolism influences and reprograms the Th17/Treg cell balance, and the metabolic pattern of T cells is different in SLE. Notably, metabolic characteristics of SLE T cells, such as enhanced glycolysis, lipid synthesis, glutaminolysis, and highly activated mTOR, all favored Th17 differentiation and function, which underlie the Th17/Treg cell imbalance in SLE patients. Targeting metabolic pathways to reverse Th17/Treg imbalance offer a promising method for SLE therapy.

Statin treatment of patients with calcific aortic valve disease modulates extracellular adenosine metabolism on the cell surface of the aortic valve

Statins efficiently prevent cardiovascular events by lipid-dependent and independent mechanisms. We hypothesize that part of these protective effects could be associated with an increased extracellular adenosine signaling. We demonstrated previously that aortic valves obtained from patients with calcific aortic valve disease (CAVD) disclosed disturbances in extracellular adenosine metabolism. This study aimed to analyze the impact of statin treatment on extracellular nucleotides and adenosine metabolism in aortic valves originated from CAVD patients and to elucidate potential mechanisms that are involved in the regulation of ecto-enzyme activities by statins. Aortic valves of CAVD patients treated with statins (n = 45) revealed higher adenosine production and its lower degradation than in non-treated patients (n = 28). Statin treatment was also related to the improvement in pre-operative echocardiographic data indicating milder aortic valve stenosis and a better function of the left ventricle. The rates of aortic valve adenosine conversions correlated with plasma lipid profile parameters, within both statin-treated and non-treated groups. Valvular extracellular AMP hydrolysis correlated negatively, while adenosine deamination positively with plasma total and LDL cholesterol. Atorvastatin treatment of murine heart endothelial cells led to the enhanced ecto-5'nucleotidase (CD73) and decreased ecto-adenosine deaminase (eADA) activity. When endothelial cells were stimulated with thrombin that induces endothelial cell exocytosis, activities of both cell-surface CD73 and eADA were increased, while co-treatment with atorvastatin reversed only thrombin-induced eADA activity. In conclusion, early intervention with statins may provide beneficial effects for CAVD therapy. Here, we presented results showing that these protective outcomes could be mediated via the regulation of extracellular adenosine metabolism pathways.

Cardiovascular risk stratification and appropriate use of statins in patients with systemic lupus erythematosus according to different strategies

INTRODUCTION/OBJECTIVES

Cardiovascular risk management of patients with systemic lupus erythematosus (SLE) is medically relevant. The objectives were to estimate the cardiovascular risk by different strategies in patients with SLE, analyzing which proportion of patients would be candidates to receive statin therapy, and identify how many patients with statin indication received such drugs.

METHOD

A cross-sectional study was performed from a secondary database. Following the recommendations of National Institute for Health and Care Excellence (NICE) guidelines and the Argentine Consensus, the QRISK-3 and the adjusted Framingham (multiplying factor × 2) scores were calculated in primary prevention subjects. The indications for statin therapy according to these recommendations were analyzed.

RESULTS

In total, 110 patients were included. Regarding patients without previous cardiovascular history, the median adjusted Framingham score was 12.8% (4.1-21.9), and 45.2%, 22.6%, and 32.2% of them were classified at low, moderate, or high risk. The median QRISK-3 score was 6.0% (2.1-14.1) and 42.1% of subjects were classified "at risk". Only 60% of subjects in secondary prevention received statins, although no patient received the recommended doses. Analyzing patients in primary prevention who did not receive statins (87%), 43.4% and 45.2% of the patients were eligible for statin therapy according to NICE guidelines and Argentine Consensus, respectively.

CONCLUSIONS

Our findings showed that a large proportion of patients with SLE have a considerable cardiovascular risk and many of them would be eligible for statin therapy. However, the statin use observed was low.Key Points• A large proportion of patients with lupus have a considerable cardiovascular risk, explained in part by dyslipidemia.• Many patients with SLE would be eligible for statin therapy according to risk stratification based on conventional risk factors.• The use of statins in this population is inadequate.

MAP4K Family Kinases and DUSP Family Phosphatases in T-Cell Signaling and Systemic Lupus Erythematosus

T cells play a critical role in the pathogenesis of systemic lupus erythematosus (SLE), which is a severe autoimmune disease. In the past 60 years, only one new therapeutic agent with limited efficacy has been approved for SLE treatment; therefore, the development of early diagnostic biomarkers and therapeutic targets for SLE is desirable. Mitogen-activated protein kinase kinase kinase kinases (MAP4Ks) and dual-specificity phosphatases (DUSPs) are regulators of MAP kinases. Several MAP4Ks and DUSPs are involved in T-cell signaling and autoimmune responses. HPK1 (MAP4K1), DUSP22 (JKAP), and DUSP14 are negative regulators of T-cell activation. Consistently, HPK1 and DUSP22 are downregulated in the T cells of human SLE patients. In contrast, MAP4K3 (GLK) is a positive regulator of T-cell signaling and T-cell-mediated immune responses. MAP4K3 overexpression-induced RORγt–AhR complex specifically controls interleukin 17A (IL-17A) production in T cells, leading to autoimmune responses. Consistently, MAP4K3 and the RORγt–AhR complex are overexpressed in the T cells of human SLE patients, as are DUSP4 and DUSP23. In addition, DUSPs are also involved in either human autoimmune diseases (DUSP2, DUSP7, DUSP10, and DUSP12) or T-cell activation (DUSP1, DUSP5, and DUSP14). In this review, we summarize the MAP4Ks and DUSPs that are potential biomarkers and/or therapeutic targets for SLE.

The Potential Use of Metformin, Dipyridamole, N-Acetylcysteine and Statins as Adjunctive Therapy for Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a chronic inflammatory autoimmune condition that can potentially affect every single organ during the course of the disease, leading to increased morbidity and mortality, and reduced health-related quality of life. While curative treatment is currently non-existent for SLE, therapeutic agents such as glucocorticoids, mycophenolate, azathioprine, cyclosporine, cyclophosphamide and various biologics are the mainstay of treatment based on their immunomodulatory and immunosuppressive properties. As a result of global immunosuppression, the side-effect profile of the current therapeutic approach is unfavourable, with adverse effects including myelosuppression, infection and malignancies. Hydroxychloroquine, one of the very few Food and Drug Administration (FDA)-approved medications for the treatment of SLE, has been shown to offer a number of therapeutic benefits to SLE patients independent of its immunomodulatory effect. As such, it is worth exploring drugs similar to hydroxychloroquine that confer additional clinical benefits unrelated to immunosuppressive mechanisms. Indeed, apart from hydroxychloroquine, a number of studies have explored the use of a few conventionally non-immunosuppressive drugs that are potentially useful in the management of SLE. In this review, non-immunosuppressive therapeutic agents, namely metformin, dipyridamole, N-acetylcysteine and statins, will be critically discussed with regard to their mechanisms of action and efficacy pertaining to their potential therapeutic role in SLE.

The cholesterol biosynthesis pathway regulates IL-10 expression in human Th1 cells

The mechanisms controlling CD4+ T cell switching from an effector to an anti-inflammatory (IL-10+) phenotype play an important role in the persistence of chronic inflammatory diseases. Here, we identify the cholesterol biosynthesis pathway as a key regulator of this process. Pathway analysis of cultured cytokine-producing human T cells reveals a significant association between IL-10 and cholesterol metabolism gene expression. Inhibition of the cholesterol biosynthesis pathway with atorvastatin or 25-hydroxycholesterol during switching from IFNγ+ to IL-10+ shows a specific block in immune resolution, defined as a significant decrease in IL-10 expression. Mechanistically, the master transcriptional regulator of IL10 in T cells, c-Maf, is significantly decreased by physiological levels of 25-hydroxycholesterol. Strikingly, progression to rheumatoid arthritis is associated with altered expression of cholesterol biosynthesis genes in synovial biopsies of predisposed individuals. Our data reveal a link between sterol metabolism and the regulation of the anti-inflammatory response in human CD4+ T cells.

Metastasis and chemoresistance in CD133 expressing pancreatic cancer cells are dependent on their lipid raft integrity

Metabolic rewiring is an integral part of tumor growth. Among metabolic pathways, the Mevalonic-Acid-Pathway (MVAP) plays a key role in maintaining membrane architecture through cholesterol synthesis, thereby affecting invasiveness. In the current study, we show for the first time that CD133^Hi pancreatic tumor initiating cells (TIC) have increased expression of MVAP enzymes, cholesterol-content and Caveolin expression. Further, we show that CD133 in these cells is localized in the lipid-rafts (characterized by Cav-1-cholesterol association). Disruption of lipid-rafts by either depleting Cav-1 or by inhibiting MVAP by lovastatin decreased metastatic-potential and chemoresistance in CD133^Hi cells while not affecting the CD133^lo cells. Additionally, disruption of lipid-raft results in deregulation of FAK-signaling, decreasing invasiveness in pancreatic-TICs. Furthermore, this also inhibits ABC-transporter activity resulting in sensitizing TICs to standard chemotherapeutic agents. Repurposing existing drugs for new clinical applications is one of the safest and least resource intensive approaches to improve therapeutic options. In this context, our study is extremely timely as it shows that targeting lipid-rafts with statins can sensitize the normally resistant pancreatic TIC^Hi-cells to standard chemotherapy and decrease metastasis, thereby defining a novel strategy for targeting the TIC^Hi-PDAC.

Defective BTLA functionality is rescued by restoring lipid metabolism in lupus CD4+ T cells

Coinhibitory receptors play an important role in the prevention of autoimmune diseases, such as systemic lupus erythematosus (SLE), by limiting T cell activation. B and T lymphocyte attenuator (BTLA) is an inhibitory receptor, similar to cytotoxic T lymphocyte-associated protein 4 (CTLA-4) and programmed death 1 (PD1), that negatively regulates the immune response. The role of BTLA in the pathogenesis of autoimmune diseases in humans and, more specifically, in SLE is largely unknown. We investigated BTLA expression on various T cell subsets, and we did not observe significant variations of BTLA expression between lupus patients and healthy controls. However, the enhancement of BTLA expression after activation was significantly lower in SLE patients compared with that in healthy controls. Furthermore, we found an impaired capacity of BTLA to inhibit T cell activation in SLE due to a poor BTLA recruitment to the immunological synapse following T cell stimulation. Finally, we demonstrated that defective BTLA function can be corrected by restoring intracellular trafficking and by normalizing the lipid metabolism in lupus CD4+ T cells. Collectively, our results evidence that the BTLA signaling pathway is altered in SLE T cells and highlight the potential of targeting this pathway for the development of new therapeutic strategies in lupus.

Impact of Dietary Cholesterol on the Pathophysiology of Infectious and Autoimmune Disease

Cellular cholesterol metabolism, lipid raft formation, and lipoprotein interactions contribute to the regulation of immune-mediated inflammation and response to pathogens. Lipid pathways have been implicated in the pathogenesis of bacterial and viral infections, whereas altered lipid metabolism may contribute to immune dysfunction in autoimmune diseases, such as systemic lupus erythematosus, multiple sclerosis, and rheumatoid arthritis. Interestingly, dietary cholesterol may exert protective or detrimental effects on risk, progression, and treatment of different infectious and autoimmune diseases, although current findings suggest that these effects are variable across populations and different diseases. Research evaluating the effects of dietary cholesterol, often provided by eggs or as a component of Western-style diets, demonstrates that cholesterol-rich dietary patterns affect markers of immune inflammation and cellular cholesterol metabolism, while additionally modulating lipoprotein profiles and functional properties of HDL. Further, cholesterol-rich diets appear to differentially impact immunomodulatory lipid pathways across human populations of variable metabolic status, suggesting that these complex mechanisms may underlie the relationship between dietary cholesterol and immunity. Given the Dietary Guidelines for Americans 2015⁻2020 revision to no longer include limitations on dietary cholesterol, evaluation of dietary cholesterol recommendations beyond the context of cardiovascular disease risk is particularly timely. This review provides a comprehensive and comparative analysis of significant and controversial studies on the role of dietary cholesterol and lipid metabolism in the pathophysiology of infectious disease and autoimmune disorders, highlighting the need for further investigation in this developing area of research.

Aberrant T Cell Signaling and Subsets in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a chronic multi-organ debilitating autoimmune disease, which mainly afflicts women in the reproductive years. A complex interaction of genetics, environmental factors and hormones result in the breakdown of immune tolerance to "self" leading to damage and destruction of multiple organs, such as the skin, joints, kidneys, heart and brain. Both innate and adaptive immune systems are critically involved in the misguided immune response against self-antigens. Dendritic cells, neutrophils, and innate lymphoid cells are important in initiating antigen presentation and propagating inflammation at lymphoid and peripheral tissue sites. Autoantibodies produced by B lymphocytes and immune complex deposition in vital organs contribute to tissue damage. T lymphocytes are increasingly being recognized as key contributors to disease pathogenesis. CD4 T follicular helper cells enable autoantibody production, inflammatory Th17 subsets promote inflammation, while defects in regulatory T cells lead to unchecked immune responses. A better understanding of the molecular defects including signaling events and gene regulation underlying the dysfunctional T cells in SLE is necessary to pave the path for better management, therapy, and perhaps prevention of this complex disease. In this review, we focus on the aberrations in T cell signaling in SLE and highlight therapeutic advances in this field.

Hypercholesterolemia induces T cell expansion in humanized immune mice

Emerging data suggest that hypercholesterolemia has stimulatory effects on adaptive immunity and that these effects can promote atherosclerosis and perhaps other inflammatory diseases. However, research in this area has relied primarily on inbred strains of mice whose adaptive immune system can differ substantially from that of humans. Moreover, the genetically induced hypercholesterolemia in these models typically results in plasma cholesterol levels that are much higher than those in most humans. To overcome these obstacles, we studied human immune system-reconstituted mice (hu-mice) rendered hypercholesterolemic by treatment with adeno-associated virus 8-proprotein convertase subtilisin/kexin type 9 (AAV8-PCSK9) and a high-fat/high-cholesterol Western-type diet (WD). These mice had a high percentage of human T cells and moderate hypercholesterolemia. Compared with hu-mice that had lower plasma cholesterol, the PCSK9-WD mice developed a T cell-mediated inflammatory response in the lung and liver. Human CD4+ and CD8+ T cells bearing an effector memory phenotype were significantly elevated in the blood, spleen, and lungs of PCSK9-WD hu-mice, whereas splenic and circulating regulatory T cells were reduced. These data show that moderately high plasma cholesterol can disrupt human T cell homeostasis in vivo. This process may not only exacerbate atherosclerosis, but also contribute to T cell-mediated inflammatory diseases in the hypercholesterolemia setting.

Tyrosine kinase inhibitors and mesenchymal stromal cells: effects on self-renewal, commitment and functions

The hope of selectively targeting cancer cells by therapy and eradicating definitively malignancies is based on the identification of pathways or metabolisms that clearly distinguish “normal” from “transformed” phenotypes. Some tyrosine kinase activities, specifically unregulated and potently activated in malignant cells, might represent important targets of therapy. Consequently, tyrosine kinase inhibitors (TKIs) might be thought as the “vanguard” of molecularly targeted therapy for human neoplasias. Imatinib and the successive generations of inhibitors of Bcr-Abl1 kinase, represent the major successful examples of TKI use in cancer treatment. Other tyrosine kinases have been selected as targets of therapy, but the efficacy of their inhibition, although evident, is less definite. Two major negative effects exist in this therapeutic strategy and are linked to the specificity of the drugs and to the role of the targeted kinase in non-malignant cells. In this review, we will discuss the data available on the TKIs effects on the metabolism and functions of mesenchymal stromal cells (MSCs). MSCs are widely distributed in human tissues and play key physiological roles; nevertheless, they might be responsible for important pathologies. At present, bone marrow (BM) MSCs have been studied in greater detail, for both embryological origins and functions. The available data are evocative of an unexpected degree of complexity and heterogeneity of BM-MSCs. It is conceivable that this grade of intricacy occurs also in MSCs of other organs. Therefore, in perspective, the negative effects of TKIs on MSCs might represent a critical problem in long-term cancer therapies based on such inhibitors.

Metabolic Factors that Contribute to Lupus Pathogenesis

Systemic lupus erythematosus (SLE) is an autoimmune disease in which organ damage is mediated by pathogenic autoantibodies directed against nucleic acids and protein complexes. Studies in SLE patients and in mouse models of lupus have implicated virtually every cell type in the immune system in the induction or amplification of the autoimmune response as well as the promotion of an inflammatory environment that aggravates tissue injury. Here, we review the contribution of CD4+ T cells, B cells, and myeloid cells to lupus pathogenesis and then discuss alterations in the metabolism of these cells that may contribute to disease, given the recent advances in the field of immunometabolism.

Excessive interferon-α signaling in autoimmunity alters glycosphingolipid processing in B cells

Excessive interferon-α (IFN-α) production by innate immune cells is a hallmark of autoimmune diseases. What other cell type secretes IFN-α and how IFN-α affects immune cell metabolism and homeostasis in autoimmunity are largely unclear. Here, we report that autoimmune B cells, arising from two different B cell-specific genetic lesions in mice, secrete IFN-α. In addition, IFN-α, found in abundance in autoimmunity, elicited profound changes in the B cell lipidome, increasing their expression of glycosphingolipids (GSLs) and leading to their CD1d-mediated depletion of iNKT cells in vitro and in vivo. IFN-α receptor blockade could reverse the loss of iNKT cells. Excessive stimulation of B cells with IFN-α altered the expression of enzymes that catalyze critical steps in GSL processing, increasing the expressions of glucosylceramide synthase (GCS) and globotrihexosylceramide synthase (Gb3S) but decreasing that of α-galactosidase A (α-galA). Inhibiting GCS or restoring α-galA expression prevented iNKT depletion by IFN-α-activated B cells. Taken together, our work indicated that excessive IFN-α perturbs GSL metabolism in B cells which in turn adversely affects iNKT homeostasis.

Cholesterol Metabolism in T Cells

Compartmentalization and spatial control of biochemical reactions is the foundation of cell-based life on earth. The lipid bilayer system employed by eukaryote cells not only keeps them separate from the environment but also provides a platform for key receptors to sense and interact with outside factors. Arguably one of the cell types most reliant on interactions of this kind, immune cells depend on their membrane to keep functioning properly. In this review, the influence of variation in cholesterol levels, a key component of lipid bilayer stability, on T cells will be discussed in detail. In comparison to other cells, T cells must be able to undergo rapid activation followed by proliferation. Furthermore, receptor colocalization is an important mechanism in this activation process. The impact of cholesterol availability on the processes of T cell proliferation and receptor sensitivity, as well as its potential for immunomodulation in disease treatment will be considered.

Transcriptional Regulation of T-Cell Lipid Metabolism: Implications for Plasma Membrane Lipid Rafts and T-Cell Function

It is well established that cholesterol and glycosphingolipids are enriched in the plasma membrane (PM) and form signaling platforms called lipid rafts, essential for T-cell activation and function. Moreover, changes in PM lipid composition affect the biophysical properties of lipid rafts and have a role in defining functional T-cell phenotypes. Here, we review the role of transcriptional regulators of lipid metabolism including liver X receptors α/β, peroxisome proliferator-activated receptor γ, estrogen receptors α/β (ERα/β), and sterol regulatory element-binding proteins in T-cells. These receptors lie at the interface between lipid metabolism and immune cell function and are endogenously activated by lipids and/or hormones. Importantly, they regulate cellular cholesterol, fatty acid, glycosphingolipid, and phospholipid levels but are also known to modulate a broad spectrum of immune responses. The current evidence supporting a role for lipid metabolism pathways in controlling immune cell activation by influencing PM lipid raft composition in health and disease, and the potential for targeting lipid biosynthesis pathways to control unwanted T-cell activation in autoimmunity is reviewed.

Immunometabolism in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease mediated by pathogenic autoantibodies directed against nucleoprotein complexes. Beyond the activation of autoreactive B cells, this process involves dysregulation in many other types of immune cells, including CD4⁺ T cells, dendritic cells, macrophages and neutrophils. Metabolic substrate utilization and integration of cues from energy sensors are critical checkpoints of effector functions in the immune system, with common as well as cell-specific programmes. Patients with SLE and lupus-prone mice present with activated metabolism of CD4⁺ T cells, and the use of metabolic inhibitors to normalize these features is associated with therapeutic effects. Far less is known about the metabolic requirements of B cells and myeloid cells in SLE. This article reviews current knowledge of the alterations in metabolism of immune cells in patients with SLE and mouse models of lupus in the context of what is known about the metabolic regulation of these cells during normal immune responses. How these alterations might contribute to lupus pathogenesis and how they can be targeted therapeutically are also discussed.

Update on cardiovascular disease in lupus

PURPOSE OF REVIEW

Atherosclerotic cardiovascular disease confers significant morbidity and mortality in patients with systemic lupus erythematosus (SLE) and cannot be fully explained by traditional cardiovascular risk factors. Recent immunologic discoveries have outlined putative pathways in SLE that may also accelerate the development of atherosclerosis.

RECENT FINDINGS

Aberrant innate and adaptive immune responses implicated in lupus pathogenesis may also contribute to the development of accelerated atherosclerosis in these patients. Defective apoptosis, abnormal lipoprotein function, autoantibodies, aberrant neutrophil responses, and a dysregulated type I interferon pathway likely contribute to endothelial dysfunction. SLE macrophages have an inflammatory phenotype that may drive progression of plaque.

SUMMARY

Recent discoveries have placed increased emphasis on the immunology of atherosclerotic cardiovascular disease. Understanding the factors that drive the increased risk for cardiovascular disease in SLE patients may provide selective therapeutic targets for reducing inflammation and improving outcomes in atherosclerosis.

Molecular Mechanisms for cAMP-Mediated Immunoregulation in T cells - Role of Anchored Protein Kinase A Signaling Units

The cyclic AMP/protein kinase A (cAMP/PKA) pathway is one of the most common and versatile signal pathways in eukaryotic cells. A-kinase anchoring proteins (AKAPs) target PKA to specific substrates and distinct subcellular compartments providing spatial and temporal specificity for mediation of biological effects channeled through the cAMP/PKA pathway. In the immune system, cAMP is a potent negative regulator of T cell receptor-mediated activation of effector T cells (Teff) acting through a proximal PKA/Csk/Lck pathway anchored via a scaffold consisting of the AKAP Ezrin holding PKA, the linker protein EBP50, and the anchoring protein phosphoprotein associated with glycosphingolipid-enriched microdomains holding Csk. As PKA activates Csk and Csk inhibits Lck, this pathway in response to cAMP shuts down proximal T cell activation. This immunomodulating pathway in Teff mediates clinically important responses to regulatory T cell (Treg) suppression and inflammatory mediators, such as prostaglandins (PGs), adrenergic stimuli, adenosine, and a number of other ligands. A major inducer of T cell cAMP levels is PG E2 (PGE2) acting through EP2 and EP4 prostanoid receptors. PGE2 plays a crucial role in the normal physiological control of immune homeostasis as well as in inflammation and cancer immune evasion. Peripherally induced Tregs express cyclooxygenase-2, secrete PGE2, and elicit the immunosuppressive cAMP pathway in Teff as one tumor immune evasion mechanism. Moreover, a cAMP increase can also be induced by indirect mechanisms, such as intercellular transfer between T cells. Indeed, Treg, known to have elevated levels of intracellular cAMP, may mediate their suppressive function by transferring cAMP to Teff through gap junctions, which we speculate could also be regulated by PKA/AKAP complexes. In this review, we present an updated overview on the influence of cAMP-mediated immunoregulatory mechanisms acting through localized cAMP signaling and the therapeutical increasing prospects of AKAPs disruptors in T-cell immune function.

Early High-dosage Atorvastatin Treatment Improved Serum Immune-inflammatory Markers and Functional Outcome in Acute Ischemic Strokes Classified as Large Artery Atherosclerotic Stroke: A Randomized Trial

Statins have beneficial effects on cerebral circulation and brain parenchyma during ischemic stroke and reperfusion. The primary hypothesis of this randomized parallel trial was that treatment with 80 mg/day of atorvastatin administered early at admission after acute atherosclerotic ischemic stroke could reduce serum levels of markers of immune-inflammatory activation of the acute phase and that this immune-inflammatory modulation could have a possible effect on prognosis of ischemic stroke evaluated by some outcome indicators. We enrolled 42 patients with acute ischemic stroke classified as large arteries atherosclerosis stroke (LAAS) randomly assigned in a randomized parallel trial to the following groups: Group A, 22 patients treated with atorvastatin 80 mg (once-daily) from admission day until discharge; Group B, 20 patients not treated with atorvastatin 80 mg until discharge, and after discharge, treatment with atorvastatin has been started. At 72 hours and at 7 days after acute ischemic stroke, subjects of group A showed significantly lower plasma levels of tumor necrosis factor-α, interleukin (IL)-6, vascular cell adhesion molecule-1, whereas no significant difference with regard to plasma levels of IL-10, E-Selectin, and P-Selectin was observed between the 2 groups. At 72 hours and 7 days after admission, stroke patients treated with atorvastatin 80 mg in comparison with stroke subjects not treated with atorvastatin showed a significantly lower mean National Institutes of Health Stroke Scale and modified Rankin scores. Our findings provide the first evidence that atorvastatin acutely administered immediately after an atherosclerotic ischemic stroke exerts a lowering effect on immune-inflammatory activation of the acute phase of stroke and that its early use is associated to a better functional and prognostic profile.

T cells as a therapeutic target in SLE

Systemic lupus erythematosus (SLE) is a multisystem autoimmune disease characterized by a loss of tolerance to multiple endogenous antigens. SLE etiology remains largely unknown, despite recent insight into the immunopathogenesis of the disease. T cells are important in the development of the disease by amplifying the immune response and contributing to organ damage. Aberrant signaling, cytokine secretion, and tissue homing displayed by SLE T cells have been extensively studied and the underlying pathogenic molecular mechanisms are starting to be elucidated. T-cell-targeted treatments are being explored in SLE patients. This review is an update on the T-cell abnormalities and related therapeutic options in SLE.

FcγRIIIa-Syk Co-signal Modulates CD4+ T-cell Response and Up-regulates Toll-like Receptor (TLR) Expression

CD4(+) T-cells in systemic lupus erythematosus (SLE) patients show altered T-cell receptor signaling, which utilizes Fc-receptor γ-chain FcRγ-Syk. A role for FcγRIIIa activation from immune complex (IC) ligation and sublytic terminal complement complex (C5b-9) in CD4(+) T-cell responses is not investigated. In this study, we show that the ICs present in SLE patients by ligating to FcγRIIIa on CD4(+) T-cells phosphorylate Syk and provide a co-stimulatory signal to CD4(+) T-cells in the absence of CD28 signal. This led to the development of pathogenic IL-17A(+) and IFN-γ(high) CD4(+) T-cells in vitro. Cytokines IL-1β, IL-6, TGF-β1, and IL-23 were the only requirement for the development of both populations. SLE patients CD4(+) T-cells that expressed CD25, CD69, and CD98 bound to ICs showed pSyk and produced IFN-γ and IL-17A. This FcγRIIIa-mediated co-signal differentially up-regulated the expression of IFN pathway genes compared with CD28 co-signal. FcγRIIIa-pSyk up-regulated several toll-like receptor genes as well as the HMGB1 and MyD88 gene transcripts. ICs co-localized with these toll-like receptor pathway proteins. These results suggest a role for the FcγRIIIa-pSyk signal in modulating adaptive immune responses.

Pathogenic immunity in systemic lupus erythematosus and atherosclerosis: common mechanisms and possible targets for intervention

Systemic lupus erythematosus (SLE) is an autoimmune disorder that primarily affects young women and is characterized by inflammation in several organs including kidneys, skin, joints, blood and nervous system. Abnormal immune cellular and humoral responses play important roles in the development of the disease process. Impaired clearance of apoptotic material is a key factor contributing to the activation of self-reactive immune cells. The incidence of atherosclerotic cardiovascular disease (CVD) is increased up to 50-fold in patients with SLE compared to age- and gender-matched controls, and this can only partly be explained by traditional risk factors for CVD. Currently, there is no effective treatment to prevent CVD complications in SLE. Traditional preventive CVD therapies have not been found to significantly lower the incidence of CVD in SLE; therefore, there is a need for novel treatment strategies and increased understanding of the mechanisms involved in the pathogenesis of CVD complications in SLE. The pathogenic immune responses in SLE and development of atherosclerotic plaques share some characteristics, such as impaired efferocytosis and skewed T-cell activation, suggesting the possibility of identifying novel targets for intervention. As novel immune-based therapies for CVD are being developed, it is possible that some of these may be effective for the prevention of CVD and for immunomodulation in SLE. However, further understanding of the mechanisms leading to an increased prevalence of cardiovascular events in SLE is critical for the development of such therapies.