Hydroxychloroquine efficiently suppresses inflammatory responses of human class-switched memory B cells via Toll-like receptor 9 inhibition

New guidelines and therapeutic updates for the management of lupus nephritis

PURPOSE OF REVIEW

Systemic lupus erythematosus (SLE) can be a devastating condition, striking young patients often in their prime reproductive years. Lupus nephritis is a common and serious complication occurring in roughly 50% of SLE cases, indicating a high likelihood of disease progression, morbidity, and mortality. As the early trials of steroid therapy, and later cyclophosphamide (CYC), therapeutic changes had been stagnant. Then came the introduction of mycophenolate mofetil (MMF) in the 2000s. After the Aspreva Lupus Management Study, there had been a dearth of trials showing positive therapy results. Since 2020, new studies have emerged for lupus nephritis involving the use of anti-BLYS agents, novel calcineurin inhibitors, CD20 blockade, and antiinterferon agents. Nephrology and rheumatology society guidelines in the United States and across the world are still catching up.

RECENT FINDINGS

Although therapeutic guidelines are being developed, updates that have come through have focused on improved diagnostic and monitoring guidelines. One theme is the recommendation of increasingly tight proteinuria control and firmer guidelines for the rapid induction of remission. The reality of multitarget therapy and the expectation of rapid induction for a more complete remission are being widely recognized.

SUMMARY

The need for more complete and more rapid induction and control of lupus nephritis is undisputed according to the evidence and guidelines, and the medications to achieve this are growing at a rate not seen over the prior two decades. What remains is a stepwise approach to recognize how to best optimize therapy. Based on available evidence, an algorithm for induction and maintenance treatment of lupus nephritis used by the University of California Irvine Lupus Nephritis clinic, is recommended.

Deciphering the immunological interactions: targeting preeclampsia with Hydroxychloroquine's biological mechanisms

Preeclampsia (PE) is a complex pregnancy-related disorder characterized by hypertension, followed by organ dysfunction and uteroplacental abnormalities. It remains a major cause of maternal and neonatal morbidity and mortality worldwide. Although the pathophysiology of PE has not been fully elucidated, a two-stage model has been proposed. In this model, a poorly perfused placenta releases various factors into the maternal circulation during the first stage, including pro-inflammatory cytokines, anti-angiogenic factors, and damage-associated molecular patterns into the maternal circulation. In the second stage, these factors lead to a systemic vascular dysfunction with consecutive clinical maternal and/or fetal manifestations. Despite advances in feto-maternal management, effective prophylactic and therapeutic options for PE are still lacking. Since termination of pregnancy is the only curative therapy, regardless of gestational age, new treatment/prophylactic options are urgently needed. Hydroxychloroquine (HCQ) is mainly used to treat malaria as well as certain autoimmune conditions such as systemic lupus and rheumatoid arthritis. The exact mechanism of action of HCQ is not fully understood, but several mechanisms of action have been proposed based on its pharmacological properties. Interestingly, many of them might counteract the proposed processes involved in the development of PE. Therefore, based on a literature review, we aimed to investigate the interrelated biological processes of HCQ and PE and to identify potential molecular targets in these processes.

Cyclical palmitoylation regulates TLR9 signalling and systemic autoimmunity in mice

Toll-like receptor 9 (TLR9) recognizes self-DNA and plays intricate roles in systemic lupus erythematosus (SLE). However, the molecular mechanism regulating the endosomal TLR9 response is incompletely understood. Here, we report that palmitoyl-protein thioesterase 1 (PPT1) regulates systemic autoimmunity by removing S-palmitoylation from TLR9 in lysosomes. PPT1 promotes the secretion of IFNα by plasmacytoid dendritic cells (pDCs) and TNF by macrophages. Genetic deficiency in or chemical inhibition of PPT1 reduces anti-nuclear antibody levels and attenuates nephritis in B6.Sle1yaa mice. In healthy volunteers and patients with SLE, the PPT1 inhibitor, HDSF, reduces IFNα production ex vivo. Mechanistically, biochemical and mass spectrometry analyses demonstrated that TLR9 is S-palmitoylated at C258 and C265. Moreover, the protein acyltransferase, DHHC3, palmitoylates TLR9 in the Golgi, and regulates TLR9 trafficking to endosomes. Subsequent depalmitoylation by PPT1 facilitates the release of TLR9 from UNC93B1. Our results reveal a posttranslational modification cycle that controls TLR9 response and autoimmunity.

Systemic Lupus Erythematosus and Cytokine Storm

Systemic lupus erythematosus (SLE) is the prototype of autoimmune diseases and can manifest with a plethora of clinical signs and symptoms associated with a myriad of laboratory abnormalities. An infrequent but potentially lethal complication of SLE is macrophage activation syndrome (MAS). The diagnosis of MAS in SLE can be very challenging due to similarities in presentation of both flares and infections, such as fever, lymphadenopathy, splenomegaly, and cytopenias. These aggravating factors contribute to the increased risk of poor outcomes in SLE-associated MAS. Indeed, at the moment MAS remains invariably lethal if untreated and still has a high mortality rate with treatment. In this chapter, we discuss several aspects of MAS in the context of SLE and in particular, the pathogenesis of MAS in SLE, how MAS presents in pediatric versus adult SLE, and, finally, MAS treatment in SLE and future directions.

Whole blood hydroxychloroquine: Does genetic polymorphism of cytochrome P450 enzymes have a role?

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease with a wide range of clinical manifestations and multifactorial etiologies ranging from environmental to genetic. SLE is associated with dysregulated immunological reactions, with increased immune complex formation leading to end-organ damages such as lupus nephritis, cutaneous lupus, and musculoskeletal disorders. Lupus treatment aims to reduce disease activity, prevent organ damage, and improve long-term patient survival and quality of life. Antimalarial, hydroxychloroquine (HCQ) is used as a first-line systemic treatment for lupus. It has shown profound efficacy in lupus and its associated conditions. However, wide variation in terms of clinical response to this drug has been observed among this group of patients. This variability has limited the potential of HCQ to achieve absolute clinical benefits. Several factors, including genetic polymorphisms of cytochrome P450 enzymes, have been stipulated as key entities leading to this inter-individual variation. Thus, there is a need for more studies to understand the role of genetic polymorphisms in CYP450 enzymes in the clinical response to HCQ. Focusing on the role of genetic polymorphism on whole blood HCQ in lupus disorder, this review aims to highlight up-to-date pathophysiology of SLE, the mechanism of action of HCQ, and finally the role of genetic polymorphism of CYP450 enzymes on whole blood HCQ level as well as clinical response in lupus.

The OSR9 Regimen: A New Augmentation Strategy for Osteosarcoma Treatment Using Nine Older Drugs from General Medicine to Inhibit Growth Drive

As things stand in 2023, metastatic osteosarcoma commonly results in death. There has been little treatment progress in recent decades. To redress the poor prognosis of metastatic osteosarcoma, the present regimen, OSR9, uses nine already marketed drugs as adjuncts to current treatments. The nine drugs in OSR9 are: (1) the antinausea drug aprepitant, (2) the analgesic drug celecoxib, (3) the anti-malaria drug chloroquine, (4) the antibiotic dapsone, (5) the alcoholism treatment drug disulfiram, (6) the antifungal drug itraconazole, (7) the diabetes treatment drug linagliptin, (8) the hypertension drug propranolol, and (9) the psychiatric drug quetiapine. Although none are traditionally used to treat cancer, all nine have attributes that have been shown to inhibit growth-promoting physiological systems active in osteosarcoma. In their general medicinal uses, all nine drugs in OSR9 have low side-effect risks. The current paper reviews the collected data supporting the role of OSR9.

From systemic lupus erythematosus to lupus nephritis: The evolving road to targeted therapies

Systemic lupus erythematosus is a chronic autoimmune disease characterized by loss of tolerance against nuclear and cytoplasmic self-antigens, induction of immunity and tissue inflammation. Lupus nephritis (LN), the most important predictor of morbidity in SLE, develops in almost 30% of SLE patients at disease onset and in up to 50-60% within the first 10 years. Firstly, in this review, we put the pathogenic mechanisms of the disease into a conceptual frame, giving emphasis to the role of the innate immune system in this loss of self-tolerance and the induction of the adaptive immune response. In this aspect, many mechanisms have been described such as dysregulation and acceleration of cell-death pathways, an aberrant clearance and overload of immunogenic acid-nucleic-containing debris and IC, and the involvement of antigen-presenting cells and other innate immune cells in the induction of this adaptive immune response. This result in a clonal expansion of autoreactive lymphocytes with generation of effector T-cells, memory B-cells and plasma cells that produce autoantibodies that will cause kidney damage. Secondly, we review the immunological pathways of damage in the kidney parenchyma, initiated by autoantibody binding and immune complex deposition, and followed by complement-mediated microvascular injury, activation of kidney stromal cells and the recruitment of leukocytes. Finally, we summarize the rationale for the treatment of LN, from conventional to new targeted therapies, focusing on their systemic immunologic effects and the minimization of podocytary damage.

B Cell Tolerance and Targeted Therapies in SLE

Systemic Lupus Erythematosus (SLE) is a chronic systemic autoimmune disease of high clinical and molecular heterogeneity, and a relapsing-remitting pattern. The disease is currently without cure and more prevalent in women. B cell tolerance and production of autoantibodies are critical mechanisms that drive SLE pathophysiology. However, how the balance of the immune system is broken and how the innate and adaptive immune systems are interacting during lupus-specific autoimmune responses are still largely unknown. Here, we review the latest knowledge on B cell development, maturation, and central versus peripheral tolerance in connection to SLE and treatment options. We also discuss the regulation of B cells by conventional T cells, granulocytes, and unconventional T cells, and how effector B cells exert their functions in SLE. We also discuss mechanisms of action of B cell-targeted therapies, as well as possible future directions based on current knowledge of B cell biology.

Guardians of Immunity: Advances in Primary Immunodeficiency Disorders and Management

Primary immunodeficiency disorders (PIDs) are a heterogeneous group of genetic conditions profoundly impacting immune function. The investigation spans various PID categories, offering insights into their distinct pathogenic mechanisms and clinical manifestations. Within the adaptive immune system, B-cell, T-cell, and combined immunodeficiencies are dissected, emphasizing their critical roles in orchestrating effective immune responses. In the realm of the innate immune system, focus is directed toward phagocytes and complement deficiencies, underscoring the pivotal roles of these components in initial defense against infections. Furthermore, the review delves into disorders of immune dysregulation, encompassing hemophagocytic lymphohistiocytosis (HLH), autoimmune lymphoproliferative syndrome (ALPS), immune dysregulation, polyendocrinopathy, enteropathy, and X-linked(IPEX), and autoimmunity polyendocrinopathy candidiasis-ectodermal dystrophy(APECED), elucidating the intricate interplay between immune tolerance and autoimmunity prevention. Diagnostic strategies for PIDs are explored, highlighting advancements in genetic and molecular techniques that enable precise identification of underlying genetic mutations and alterations in immune function. We have also outlined treatment modalities for PIDs, which often entail a multidisciplinary approach involving immunoglobulin replacement, antimicrobial prophylaxis, and, in select cases, hematopoietic stem cell transplantation. Emerging therapies, including gene therapy, hold promise for targeted interventions. In essence, this review encapsulates the complexity of PIDs, emphasizing the critical importance of early diagnosis and tailored therapeutic interventions. As research advances, a clearer understanding of these disorders emerges, fostering optimism for enhanced patient care and management in the future.

Immunosuppression by hydroxychloroquine: mechanistic proof in in vitro experiments but limited systemic activity in a randomized placebo-controlled clinical pharmacology study

Based on its wide range of immunosuppressive properties, hydroxychloroquine (HCQ) is used for the treatment of several autoimmune diseases. Limited literature is available on the relationship between HCQ concentration and its immunosuppressive effect. To gain insight in this relationship, we performed in vitro experiments in human PBMCs and explored the effect of HCQ on T and B cell proliferation and Toll-like receptor (TLR)3/TLR7/TLR9/RIG-I-induced cytokine production. In a placebo-controlled clinical study, these same endpoints were evaluated in healthy volunteers that were treated with a cumulative dose of 2400 mg HCQ over 5 days. In vitro, HCQ inhibited TLR responses with IC50s > 100 ng/mL and reaching 100% inhibition. In the clinical study, maximal HCQ plasma concentrations ranged from 75 to 200 ng/mL. No ex vivo HCQ effects were found on RIG-I-mediated cytokine release, but there was significant suppression of TLR7 responses and mild suppression of TLR3 and TLR9 responses. Moreover, HCQ treatment did not affect B cell and T cell proliferation. These investigations show that HCQ has clear immunosuppressive effects on human PBMCs, but the effective concentrations exceed the circulating HCQ concentrations under conventional clinical use. Of note, based on HCQ's physicochemical properties, tissue drug concentrations may be higher, potentially resulting in significant local immunosuppression. This trial is registered in the International Clinical Trials Registry Platform (ICTRP) under study number NL8726.

Comparison between hydroxychloroquine and systemic corticosteroids in IgA nephropathy: a two-year follow-up study

BACKGROUND

Hydroxychloroquine (HCQ) is recommended as a treatment for IgA nephropathy (IgAN) to control proteinuria. The long-term effects of HCQ compared to systemic corticosteroid therapy remain unclear.

METHODS

We conducted a retrospective case‒control study at Peking University First Hospital. Thirty-nine patients with IgAN who received HCQ for at least 24 months without corticosteroids (CSs) or other immunosuppressive agents were included. Thirty-nine matched patients who received systemic CS therapy were selected using propensity score matching. Clinical data over a 24-month period were compared.

RESULTS

In the HCQ group, the level of proteinuria decreased from 1.72 [1.44, 2.35] to 0.97 [0.51, 1.37] g/d (-50.5 [-74.0, -3.4] %, P < 0.001) at 24 months. A significant decline in proteinuria was also found in the CS group, but no significant differences were found between the HCQ group and CS group in the levels of proteinuria (0.97 [0.51, 1.37] vs. 0.53 [0.25, 1.81] g/d, P = 0.707) and change rates (-50.5% [-74.0%, -3.4%] vs. -63.7% [-78.5%, -24.2%], P = 0.385) at 24 months. In addition, the decline rates of eGFR between the HCQ and CS groups were comparable (-7.9% [-16.1%, 5.8%] vs. -6.6% [-14.9%, 5.3%], P = 0.758). More adverse events were observed in the CS group.

CONCLUSIONS

Long-term use of HCQ can maintain stable renal function with minimal side effects. In patients who cannot tolerate corticosteroids, HCQ might be an effective and safe supportive therapy for IgAN.

Chloroquine inhibits NLRP3 inflammasomes activation and alleviates renal fibrosis in mouse model of hyperuricemic nephropathy with aggravation by a high-fat-diet

Numerous epidemiological studies have demonstrated that hyperuricemia (HUA) is a risk factor for renal diseases and renal fibrosis. Dietary patterns can influence serum urate levels and hyperuricemic nephropathy (HN). NLRP3 inflammasomes play a crucial role in various inflammatory responses and contribute to HN progression. Chloroquine (CQ) is an anti-inflammatory and disease-modifying anti-rheumatic drug (DMARD) utilized in treating autoimmune diseases such as rheumatoid arthritis and systemic lupus erythematosus. In this study, we examined the effects and underlying mechanisms of CQ in a high-fat-diet (HFD) exacerbated mouse model of HN. C57BL/6 mice were randomized into either a control group or an HN group (induced by adenine/potassium oxonate treatment), followed by a normal diet or HFD, with or without CQ treatment. Our findings revealed that the HN group exhibited elevated serum levels of blood urea nitrogen (BUN) and creatinine compared to the control group. Additionally, the HN + HFD group displayed increased serum levels of uric acid, BUN, and creatinine relative to the control + HFD group. Moreover, the HFD exacerbated renal uric acid crystal deposition and fibrosis in HN mice compared to a normal diet. CQ ameliorated renal dysfunction, as evidenced by reduced serum creatinine levels, renal fibrosis, and renal tubular injury scores, and significantly decreased NLRP3, ASC, caspase-1, and IL-1β levels in HN mice. These findings suggest that CQ inhibits the activation of NLRP3 inflammasomes and may serve as a potential therapeutic strategy for HN treatment.

Cyclophosphamide induced intestinal injury is alleviated by blocking the TLR9/caspase3/GSDME mediated intestinal epithelium pyroptosis

OBJECTIVES

Cyclophosphamide (CYC) was commonly used to treat autoimmune disorders, and it could also cause side effects such as intestinal damage. This study aimed to explore the mechanism of CYC-induced intestinal cytotoxicity and provide evidence for protecting from intestinal damage by blocking TLR9/caspase3/GSDME mediated pyroptosis.

METHODS

Intestinal epithelial cells (IEC-6) were treated with 4-hydroxycyclophosphamide (4HC), a key active metabolite of CYC. The pyroptotic rate of IEC-6 cells was detected by Annexin V/PI-Flow cytometry, microscopy imaging, and PI staining. The expression and activation of TLR9, caspase3 and GSDME in IEC-6 cells were detected by western blot and immunofluorescence staining. In addition, hydroxychloroquine (HCQ) and ODN2088 were used to inhibit TLR9 to investigate the role of TLR9 on caspase3/GSDME-mediated pyroptosis. Finally, mice lacking Gsdme or TLR9 or pretreating with HCQ were injected intraperitoneally with CYC, and the incidence and severity of intestinal damage were assessed.

RESULTS

CYC induced lytic cell death in IEC-6 cells and increased the expression of TLR9, activated caspase3, and GSDME-N. Besides, both ODN2088 and HCQ could inhibit CYC-induced pyroptosis in IEC-6 cells. In vivo, CYC-induced intestinal injury was characterized by a large amount of intestinal villi abscission and structural disordered. Gsdme or TLR9 deficiency, or pretreatment of HCQ effectively attenuated intestinal damage in CYC-induced model mice.

CONCLUSIONS

These results indicate an alternative mechanism for CYC-induced intestinal damage, which actives TLR9/caspase3/GSDME signaling pathway, leading to pyroptosis of intestinal epithelial cells. And targeting pyroptosis might be a potential therapeutic approach for CYC-induced intestinal damage.

IgA Nephropathy: Current Understanding and Perspectives on Pathogenesis and Targeted Treatment

Immunoglobulin A nephropathy (IgAN) is the most common primary glomerulonephritis worldwide, with varied clinical and histopathological features between individuals, particularly across races. As an autoimmune disease, IgAN arises from consequences of increased circulating levels of galactose-deficient IgA1 and mesangial deposition of IgA-containing immune complexes, which are recognized as key events in the widely accepted "multi-hit" pathogenesis of IgAN. The emerging evidence further provides insights into the role of genes, environment, mucosal immunity and complement system. These developments are paralleled by the increasing availability of diagnostic tools, potential biomarkers and therapeutic agents. In this review, we summarize current evidence and outline novel findings in the prognosis, clinical trials and translational research from the updated perspectives of IgAN pathogenesis.

Hydroxychloroquine in obstetric antiphospholipid syndrome: rationale and results of an observational study of refractory cases

BACKGROUND

The current recommended therapy of obstetric antiphospholipid syndrome (APS) is a long-term anticoagulant therapy that affects the final event, namely, when the thrombosis has already occurred. Unfortunately, this schedule is not always effective and fails despite the correct risk stratification and an adequate adjusted dose.

MATERIALS AND METHODS

From 2013 to 2020 we observed 217 women with antiphospholipid antibodies and obstetric morbidities who were treated with conventional treatment protocol (aspirin low doses ± LMWH). Among them 150 (69.1%) successfully completed pregnancy with delivery and live birth on the background of LMWH and aspirin therapy and in 67 (30.9%) women despite a traditional therapy regimen, obstetric complications were noted. Later, 56 of these 67 women became pregnant again and were offered traditional therapy plus hydroxychloroquine. Fifteen women refused HCQ treatment due to possible potential side effects. The final cohort consisted of 41 women with positive antiphospholipid antibodies and obstetric and thrombotic complications who received LMWH, aspirin low doses and HCQ at a dose of 200-400mg per day from the beginning of pregnancy.

RESULTS

Forty-one aPL women treated with HCQ after failed previous anticoagulant therapy had live births in 32 cases (78%). Adding of HCQ to the combination of LMWH and LDA showed good overall obstetric results and increased the number of live births in another 32 women. So, a total of 182 (83.8%) of initial 217 aPL-women ended their pregnancies with live birth after adding the HCQ to the traditional therapy with LMWH and low doses of aspirin.

CONCLUSION

In 20-30% of cases the live birth despite anticoagulation cannot be achieved. Perhaps APS is not just anticoagulation. The study of pathophysiological mechanisms suggests that some patients will benefit from other therapy (in addition to anticoagulant). Therapy that affects the early effects of aPL on target cells (monocytes, endothelial cells, etc.) or before binding to receptors-this therapy will be preferable and potentially less harmful than the officially accepted one to date. From this point of view, HCQ looks promising and can be used as an alternative candidate for women with refractory obstetric antiphospholipid syndrome. Adding HCQ should be considered in some selected patients with failed pregnancy after treatment with anticoagulants.

Stress, mindfulness, and systemic lupus erythematosus: An overview and directions for future research

Although the pathogenesis of autoimmunity is not fully understood, it is thought to involve genetic, hormonal, immunologic, and environmental factors. Stress has been evaluated as a potential trigger for autoimmunity and disease flares in patients with systemic lupus erythematosus (SLE). The physiologic changes that occur with stress involve numerous catecholamines, hormones, and cytokines that communicate intricately with the immune system. There is some evidence that these systems may be dysregulated in patients with autoimmune disease. Mindfulness-based techniques are practices aimed at mitigating stress response and have been shown to improve quality of life in general population. This review will discuss pathophysiology of chronic stress as it relates to SLE, evidence behind mindfulness-based practices in these patients, and directions for future research.

Effect of add-on hydroxychloroquine therapy on serum proinflammatory cytokine levels in patients with systemic lupus erythematosus

We investigated the effect of hydroxychloroquine (HCQ) as an add-on treatment to immunosuppressants on the expression of proinflammatory cytokines in patients with systemic lupus erythematosus. Serum levels of tumor necrosis factor (TNF)-α, interleukin (IL)-2, IL-6, IL-8, vascular endothelial growth factor (VEGF)-A, monocyte chemotactic protein-1 (MCP-1), macrophage inflammatory protein-1α (MIP-1α), and interleukin 1 receptor antagonist (IL-1ra) were measured immediately before and 3 months after treatment with oral HCQ. Among the 51 patients enrolled in the study, HCQ treatment led to significantly reduced serum levels of TNF-α, IL-6, IL-8, VEGF-A, IL-1ra, and IL-2 (p < 0.0001; p = 0.0006; p = 0.0460, p = 0.0177; p < 0.0001; p = 0.0282, respectively) and to decreased (but not significantly) levels of MIP-1α (p = 0.0746). No significant changes were observed in the serum MCP-1 levels before and after HCQ administration (p = 0.1402). Our results suggest that an add-on HCQ treatment modulates the expression of proinflammatory cytokines even in systemic lupus erythematosus patients with low disease activity.

Chloroquine Suppresses Effector B-Cell Functions and Has Differential Impact on Regulatory B-Cell Subsets

Objectives

Chloroquine (CQ) is approved for treatment of B-cell mediated diseases such as rheumatoid arthritis and systemic lupus erythematosus. However, the exact mode of action in these diseases has not been studied and it remains unclear which effect CQ has on B-cells. Thus, it was the aim of this study to investigate to which extent CQ affects functionality of effector and regulatory B-cell.

Methods

For this purpose, B-cells were isolated from peripheral blood of healthy controls and renal transplant patients. B-cells were stimulated in presence or absence of CQ and Interleukin-10 (IL-10) and Granzyme B (GrB) secretion were assessed. In addition, effector functions such as plasma cell formation, and Immunoglobulin G (IgG) secretion were studied.

Results

CQ suppressed Toll-Like-Receptor (TLR)-9 induced B-cell proliferation in a dose-dependent manner. IL-10^pos regulatory B-cells were suppressed by CQ already at low concentrations whereas anti-IgG/IgM-induced GrB secreting regulatory B-cells were less susceptible. Plasma blast formation and IgG secretion was potently suppressed by CQ. Moreover, purified B-cells from renal transplant patients were also susceptible to CQ-induced suppression of effector B-cell functions as observed by diminished IgG secretion.

Conclusion

In conclusion, CQ had a suppressive effect on IL-10 regulatory B-cells whereas GrB secreting regulatory B-cells were less affected. Effector functions of B-cells such as plasma blast formation and IgG secretion were also inhibited by CQ. Effector B-cells derived from renal transplant patients already under immunosuppression could be suppressed by CQ. These findings may partly explain the clinical efficacy of CQ in B-cell mediated autoimmune diseases. The application of CQ in other disease contexts where suppression of effector B-cells could offer a benefit, such as renal transplantation, may hypothetically be advantageous.

Hydroxychloroquine attenuates neuroinflammation following traumatic brain injury by regulating the TLR4/NF-κB signaling pathway

Background

After traumatic brain injury (TBI), an acute, robust inflammatory cascade occurs that is characterized by the activation of resident cells such as microglia, the migration and recruitment of peripheral immune cells and the release of inflammatory mediators that induce secondary cell death and impede neurological recovery. In addition, neuroinflammation can alter blood–brain barrier (BBB) permeability. Controlling inflammatory responses is considered a promising therapeutic approach for TBI. Hydroxychloroquine (HCQ) has already been used clinically for decades, and it is still widely used to treat various autoimmune diseases. However, the effects of HCQ on inflammation and the potential mechanism after TBI remain to be defined. The aim of the current study was to elucidate whether HCQ could improve the neurological recovery of mice post-TBI by inhibiting the inflammatory response via the TLR4/NF-κB signaling pathway.

Methods

C57BL/6 mice were subjected to controlled cortical impact (CCI) and randomly divided into groups that received intraperitoneal HCQ or vehicle daily after TBI. TAK-242 (3.0 mg/kg), an exogenous TLR4 antagonist, was injected intraperitoneally 1 h before TBI. Behavioral assessments were performed on days 1 and 3 post-TBI, and the gene expression levels of inflammatory cytokines were analyzed by qRT-PCR. The presence of infiltrated immune cells was examined by flow cytometry and immunostaining. In addition, BBB permeability, tight junction expression and brain edema were investigated.

Results

HCQ administration significantly ameliorated TBI-induced neurological deficits. HCQ alleviated neuroinflammation, the activation and accumulation of microglia and immune cell infiltration in the brain, attenuated BBB disruption and brain edema, and upregulated tight junction expression. Combined administration of HCQ and TAK-242 did not enhance the neuroprotective effects of HCQ.

Conclusions

HCQ reduced proinflammatory cytokine expression, and the underlying mechanism may involve suppressing the TLR4/NF-κB signaling pathway, suggesting that HCQ is a potential therapeutic agent for TBI treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02430-0.

Effects of Hydroxychloroquine on Proteinuria in IgA Nephropathy: A Systematic Review and Meta-Analysis

Introduction

The present meta-analysis was to explore the efficacy of hydroxychloroquine (HCQ) in IgA nephropathy patients in terms of proteinuria.

Method

We systematically searched PubMed and Embase for studies that compared HCQ and other treatments to reduce proteinuria in patients with IgA nephropathy up to June 2021. Mean ± SD of percentage change and level of proteinuria was calculated.

Results

A total of 5 studies with 587 participants were included. IgA nephropathy patients who received HCQ were at a lower level of mean proteinuria at 6 months. However, there was no statistical difference between HCQ and control group considering percentage reduction in proteinuria. The long-term therapeutic effect of HCQ might be inferior to HCQ and renin-angiotensin-aldosterone system inhibition.

Conclusion

HCQ might play a role in the reduction of proteinuria in IgA nephropathy patients. The addition of HCQ to other immunosuppressive agents should be clarified further.

Therapeutic Interventions Targeting Innate Immune Receptors: A Balancing Act

The innate immune system is an organism's first line of defense against an onslaught of internal and external threats. The downstream adaptive immune system has been a popular target for therapeutic intervention, while there is a relative paucity of therapeutics targeting the innate immune system. However, the innate immune system plays a critical role in many human diseases, such as microbial infection, cancer, and autoimmunity, highlighting the need for ongoing therapeutic research. In this review, we discuss the major innate immune pathways and detail the molecular strategies underpinning successful therapeutics targeting each pathway as well as previous and ongoing efforts. We will also discuss any recent discoveries that could inform the development of novel therapeutic strategies. As our understanding of the innate immune system continues to develop, we envision that therapies harnessing the power of the innate immune system will become the mainstay of treatment for a wide variety of human diseases.

Compromised mitochondrial quality control triggers lipin1-related rhabdomyolysis

LPIN1 mutations are responsible for inherited recurrent rhabdomyolysis, a life-threatening condition with no efficient therapeutic intervention. Here, we conduct a bedside-to-bench-and-back investigation to study the pathophysiology of lipin1 deficiency. We find that lipin1-deficient myoblasts exhibit a reduction in phosphatidylinositol-3-phosphate close to autophagosomes and late endosomes that prevents the recruitment of the GTPase Armus, locks Rab7 in the active state, inhibits vesicle clearance by fusion with lysosomes, and alters their positioning and function. Oxidized mitochondrial DNA accumulates in late endosomes, where it activates Toll-like receptor 9 (TLR9) and triggers inflammatory signaling and caspase-dependent myolysis. Hydroxychloroquine blocks TLR9 activation by mitochondrial DNA in vitro and may attenuate flares of rhabdomyolysis in 6 patients treated. We suggest a critical role for defective clearance of oxidized mitochondrial DNA that activates TLR9-restricted inflammation in lipin1-related rhabdomyolysis. Interventions blocking TLR9 activation or inflammation can improve patient care in vivo.

Therapeutic perspectives on the metabolism of lymphocytes in patients with rheumatoid arthritis and systemic lupus erythematosus

INTRODUCTION

The activation of autoreactive T- and B-cells and production of autoantibodies by B cells are involved in the pathogenesis of autoimmune diseases such as systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). Recently, the concept of 'immunometabolism' has attracted significant attention. Immune cells produce large amounts of energy in the form of ATP and biosynthesize biological components such as nucleic acids and lipids via metabolic reprogramming to activate, differentiate, and exert their functions.

AREAS COVERED

While the mechanisms underlying the metabolism of CD4⁺ T cells in SLE have been extensively studied, the metabolic changes underlying B cell activation, differentiation, and function remain unclear. Drugs targeting mTOR and AMPK, such as sirolimus, rapamycin, and metformin, have shown some efficacy and tolerability in clinical trials on patients with SLE, but have not led to breakthroughs. In this review, we summarize the current knowledge on the immunometabolic mechanisms involved in SLE and RA and discuss the potential novel therapeutic drugs.

EXPERT OPINION

The intensity of activation of different immune cells and their metabolic kinetics vary in different autoimmune diseases; thus, understanding the disease- and cell-specific metabolic mechanisms may help in the development of clinically effective immunometabolism-targeting drugs.

Exploring insights of hydroxychloroquine, a controversial drug in Covid-19: An update

The review summarizes chloroquine (CQ) and its safer derivative hydroxychloroquine (HCQ) and its utility in Covid-19. Recently this well-established drug made its way back to the headlines during the SARS-CoV-2 pandemic. This led to an upsurge in the scientific arena with multiple research and review articles along with expert opinions and commentaries. The HCQ has received mixed judgements so far about its efficacy to be used in Covid-19 patients in a limited trial conducted all across the Globe. The purpose of our article is to put forth the history, pharmacodynamics, and pharmacokinetics, along with the existing studies favouring and disapproving the role of HCQ in the treatment of Covid-19. We grouped HCQ use at three stages, this includes HCQ for i. prophylactic use by asymptomatic health workers or peoples at higher risk; ii. patients having mild symptoms; iii. patients with extreme symptoms. The review critically discusses the underlying plausible reasons and mechanisms exploring HCQ in prophylactic management or treatment of SARS-CoV-2. Furthermore, we have critically analysed the reported pharmacokinetic parameters and compiled the proponent, opponent, or neutral opinions on the use of HCQ in Covid-19. Authors discretion is to conduct more studies considering the optimal dosing regimen and pharmacokinetics assessment.

Activation of Toll-Like Receptor 7 Signaling Pathway in Primary Sjögren's Syndrome-Associated Thrombocytopenia

Objectives: To identify the importance of the Toll-like receptor (TLR) pathway using B cell high-throughput sequencing and to explore the participation of the TLR7 signaling pathway in primary Sjogren's syndrome (pSS)-associated thrombocytopenia in patient and mouse models.

Methods: High-throughput gene sequencing and bioinformatic analyses were performed for 9 patients: 3 patients with pSS and normal platelet counts, 3 patients with pSS-associated thrombocytopenia, and 3 healthy controls. Twenty-four patients with pSS were recruited for validation. Twenty-four non-obese diabetic (NOD) mice were divided into the TLR7 pathway inhibition (CA-4948), activation (Resiquimod), and control groups. Serum, peripheral blood, bone marrow, and submandibular glands were collected for thrombocytopenia and TLR7 pathway analysis.

Results: Seven hub genes enriched in the TLR pathway were identified. Compared to that in control patients, the expression of interleukin (IL)-8 and TLR7 pathway molecules in B-cells was higher in patients with pSS-associated thrombocytopenia. Platelet counts exhibited a negative correlation with serum IL-1β and IL-8 levels. In NOD mice, CA-4948/Resiquimod treatment induced the downregulation/upregulation of the TLR7 pathway, leading to consistent elevation/reduction of platelet counts. Megakaryocyte counts in the bone marrow showed an increasing trend in the Resiquimod group, with more naked nuclei. The levels of IL-1β and IL-8 in the serum and submandibular gland tissue increased in the Resiquimod group compared with that in CA-4948 and control groups.

Conclusion: pSS-associated thrombocytopenia may be a subset of the systemic inflammatory state as the TLR7 signaling pathway was upregulated in B cells of patients with pSS-associated thrombocytopenia, and activation of the TLR7 pathway led to a thrombocytopenia phenotype in NOD mice.

Hydroxychloroquine Effects on TLR Signalling: Underexposed but Unneglectable in COVID-19

The main basis for hydroxychloroquine (HCQ) treatment in COVID-19 is the compound's ability to inhibit viral replication in vitro. HCQ also suppresses immunity, mainly by interference in TLR signalling, but reliable clinical data on the extent and nature of HCQ-induced immunosuppression are lacking. Here, we discuss the mechanistic basis for the use of HCQ against SARS-CoV-2 in a prophylactic setting and in a therapeutic setting, at different stages of the disease. We argue that the clinical effect of prophylactic or therapeutic HCQ treatment in COVID-19 depends on the balance between inhibition of viral replication, immunosuppression, and off-target side effects, and that the outcome is probably dependent on disease stage and disease severity. This is supported by the initial outcomes of the well-designed randomized controlled trials: so far, evidence for a beneficial effect of HCQ treatment for COVID-19 is weak and conflicting.

Formulation and stability study of hydroxychloroquine sulfate oral suspensions

Hydroxychloroquine is an antimalarial drug indicated in the treatment of acute attacks of malaria due to Plasmodium vivax, P. malariae, P. ovale, and susceptible strains of P. falciparum. It is also used for the treatment of rheumatoid arthritis, discoid and systemic lupus erythematosus, and more recently proposed in COVID-19 therapy. Hydroxychloroquine is only available in tablets which are not easy to administer for pediatric and geriatric patients, and patients unable to swallow such as patients found in intensive care units. The aim of this work was to develop and optimize a ready to use liquid hydroxychloroquine formulation and to carry out the corresponding chemical and microbiological stability studies. The formulation was evaluated for ease of preparation, physical properties, and palatability. Its stability was performed at ambient temperature and under refrigeration. After 6 months of stability testing, the results showed no pH change, no drug loss, no microbial development, and no visual change. The formulation, employing excipients in a range that EMA has recommended, showed chemical and microbiological stability for at least 6 months even in the worst storage conditions.

Toll-like receptor signalling in B cells during systemic lupus erythematosus

B lymphocytes have a central role in autoimmune diseases, which are often defined by specific autoantibody patterns and feature a loss of B cell tolerance. A prototypic disease associated with B cell hyperactivity is systemic lupus erythematosus (SLE). In patients with SLE, the loss of B cell tolerance to autoantigens is controlled in a cell-intrinsic manner by Toll-like receptors (TLRs), which sense nucleic acids in endosomes. TLR7 drives the extrafollicular B cell response and the germinal centre reaction that are involved in autoantibody production and disease pathogenesis. Surprisingly, TLR9 seems to protect against SLE, even though it is required for the production of autoantibodies recognizing double-stranded DNA-associated antigens, which are abundant in SLE and are a hallmark of this disease. The protective function of TLR9 is at least partly mediated by its capacity to limit the stimulatory activity of TLR7. The roles of TLR7 and TLR9 in the effector function of B cells in lupus-like disease and in patients with SLE, and the unique features of TLR signalling in B cells, suggest that targeting TLR signalling in SLE might be therapeutically beneficial.

Loss of B cell tolerance to autoantigens in systemic lupus erythematosus (SLE) is driven by TLR7, whereas TLR9 appears to protect against SLE by limiting the stimulatory activity of TLR7. The unique features of Toll-like receptor signalling in B cells implicate it as a therapeutic target in SLE.

Intrinsic TLR7 and TLR9 signalling in B cells plays an important role in the development and pathogenesis of systemic lupus erythematosus (SLE).

In patients with SLE, effector plasma cells are generated via the extrafollicular response and via the formation of spontaneous germinal centres.

TLR7 plays key roles in the extrafollicular response and the response mediated by germinal centres.

Some plasma cells produce IL-10 and can have protective roles in lupus-like disease.

The treatment of SARS-CoV2 with antivirals and mitigation of the cytokine storm syndrome: the role of gene expression

In the absence of a vaccine, the treatment of SARS-CoV2 has focused on eliminating the virus with antivirals or mitigating the cytokine storm syndrome (CSS) that leads to the most common cause of death: respiratory failure. Herein we discuss the mechanisms of antiviral treatments for SARS-CoV2 and treatment strategies for the CSS. Antivirals that have shown in vitro activity against SARS-CoV2, or the closely related SARS-CoV1 and MERS-CoV, are compared on the enzymatic level and by potency in cells. For treatment of the CSS, we discuss medications that reduce the effects or expression of cytokines involved in the CSS with an emphasis on those that reduce IL-6 because of its central role in the development of the CSS. We show that some of the medications covered influence the activity or expression of enzymes involved in epigenetic processes and specifically those that add or remove modifications to histones or DNA. Where available, the latest clinical data showing the efficacy of the medications is presented. With respect to their mechanisms, we explain why some medications are successful, why others have failed, and why some untested medications may yet prove useful.

Impact of hydroxychloroquine on the gestational outcomes of pregnant women with immune system problems that necessitate the use of the drug

AIM

To evaluate the impact of hydroxychloroquine (HCQ) on the perinatal outcomes of pregnancies with immune system disorders that necessitate the use of the drug.

METHODS

This cohort consisted of 202 pregnancies with poor obstetric history and immune system problems. Patients enrolled in special antenatal care program were administered low-dose low-molecular-weight heparin, low-dose salicylic acid and low-dose corticosteroid (prophylaxis protocol) as soon as their pregnancies were confirmed. Pregnancies with systemic lupus erythematosis, Sjogren syndrome and rheumatoid arthritis were additionally administered HCQ 200 mg daily as a part of their routine treatment. Pregnancies using HCQ were included in the study group (n = 39) while the remainders were included in control group (n = 163). We compared the groups in terms of the presence of miscarriage, fetal growth restriction (FGR), preeclampsia and preterm birth, as well as gestational week at birth, birthweight and "APGAR score of <7" at 10th minute.

RESULTS

Miscarriage rates were 28.2% and 28.2% while preterm birth rates were 16.6% and 28.2% in the control and study groups, respectively (P = 0.215). Preeclampsia and HCQ-related side effects were not detected in the groups. There were also no significant differences between the groups in terms of FGR, gestational day at birth, birthweight and the presence of "APGAR score <7" at 10th minute (P = 0.462, P = 0.064, P = 0.273 and P = 0.627, respectively).

CONCLUSION

Low-dose low-molecular-weight heparin, low-dose salicylic acid and low-dose corticosteroid prophylaxis together with HCQ seem to be promising in pregnancies with immune system disorders. HCQ seems to be a safe and effective drug in low dosages.

Toll-Like Receptors, Infections, and Rheumatoid Arthritis

Toll-like receptors (TLR) that belong to the group of protein recognition receptor (PPR) provide an innate immune response following the sensing of conserved pathogen-associated microbial patterns (PAMPs) and changes in danger-associated molecular patterns (DAMPs) that are generated as a consequence of cellular injury. Analysis of the TLR pathway has moreover offered new insights into the pathogenesis of rheumatoid arthritis (RA). Indeed, a dysfunctional TLR-mediated response characterizes RA patients and participates in establishment of a chronic inflammatory state. Such an inappropriate TLR response has been attributed (i) to the report of important alterations in the microbiota and abnormal responses to infectious agents as part of RA; (ii) to the abnormal presence of TLR-ligands in the serum and synovial fluid of RA patients; (iii) to the overexpression of TLR molecules; (iv) to the production of a large panel of pro-inflammatory cytokines downstream of the TLR pathway; and (v) to genetic variants and epigenetic factors in susceptible RA patients promoting a hyper TLR response. As a consequence, the development of promising therapeutic strategies targeting TLRs for the treatment and prevention of RA is emerging.

A case report of toxic epidermal necrolysis (TEN) in a patient with COVID-19 treated with hydroxychloroquine: are these two partners in crime?

BACKGROUND

Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis (SJS/TEN) is the most Serious Cutaneous Adverse Reaction (SCAR) often with a fatal outcome. Coronavirus Disease (COVID-19) is caused by Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-COV2) and is an emergent pandemic for which no cure exist at the moment. Several drugs have been tried often with scant clinical evidence and safety.

CASE PRESENTATION

Here we report the case of 78-years-old woman with cardiometabolic syndrome and COVID-19. A multidrug regimen including others hydroxychloroquine, antibiotics, dexamethasone and paracetamol, low-molecular-weight-heparin and potassium canrenoate was started. After almost 3 weeks, the patient started to display a violaceous rash initially involving the flexural folds atypical targetoid lesions and showing a very fast extension, blister formation and skin detachments of approximately 70% of the total body surface area and mucous membranes involvement consistent with toxic epidermal necrolysis (TEN). The ALDEN algorithm was calculated inserting all drugs given to the patient in the 28 days preceding the onset of the skin manifestations. The highest score retrieved was for hydroxychloroquine. Other less suspicious drugs were piperacillin/tazobactam, ceftriaxone and levofloxacin.

CONCLUSIONS

To our knowledge, this is the first case of TEN in a patient suffering from COVID-19 probably associated with hydroxychloroquine. Given the activation of the immune system syndrome induced by the virus and the widespread off-label use of this drug, we suggest a careful monitoring of skin and mucous membranes in all COVID-19 positive patients treated with hydroxychloroquine in order to early detect early signs of toxicities.

Elucidating the Pivotal Immunomodulatory and Anti-Inflammatory Potentials of Chloroquine and Hydroxychloroquine

Chloroquine (CQ) and hydroxychloroquine (HCQ) are derivatives of 4-aminoquinoline compounds with over 60 years of safe clinical usage. CQ and HCQ are able to inhibit the production of cytokines such as interleukin- (IL-) 1, IL-2, IL-6, IL-17, and IL-22. Also, CQ and HCQ inhibit the production of interferon- (IFN-) α and IFN-γ and/or tumor necrotizing factor- (TNF-) α. Furthermore, CQ blocks the production of prostaglandins (PGs) in the intact cell by inhibiting substrate accessibility of arachidonic acid necessary for the production of PGs. Moreover, CQ affects the stability between T-helper cell (Th) 1 and Th2 cytokine secretion by augmenting IL-10 production in peripheral blood mononuclear cells (PBMCs). Additionally, CQ is capable of blocking lipopolysaccharide- (LPS-) triggered stimulation of extracellular signal-modulated extracellular signal-regulated kinases 1/2 in human PBMCs. HCQ at clinical levels effectively blocks CpG-triggered class-switched memory B-cells from differentiating into plasmablasts as well as producing IgG. Also, HCQ inhibits cytokine generation from all the B-cell subsets. IgM memory B-cells exhibits the utmost cytokine production. Nevertheless, CQ triggers the production of reactive oxygen species. A rare, but serious, side effect of CQ or HCQ in nondiabetic patients is hypoglycaemia. Thus, in critically ill patients, CQ and HCQ are most likely to deplete all the energy stores of the body leaving the patient very weak and sicker. We advocate that, during clinical usage of CQ and HCQ in critically ill patients, it is very essential to strengthen the CQ or HCQ with glucose infusion. CQ and HCQ are thus potential inhibitors of the COVID-19 cytokine storm.

Mutagenic, Genotoxic and Immunomodulatory effects of Hydroxychloroquine and Chloroquine: a review to evaluate its potential to use as a prophylactic drug against COVID-19

Hydroxychloroquine (HCQ) and Chloroquine (CQ) are two anti-malarial drugs that are now being extensively used by front-line healthcare workers and other common people as a prophylactic drug against the Corona Virus Disease − 19 (COVID-19) in India and as well as in many parts of the world. While only a few in vitro studies have pointed to some efficacy of these drugs as a prophylactic against COVID-19, to date, there are no clinical studies that have established any clinical efficacy of these drugs as a prophylactic. These drugs are commonly used for the treatment of Rheumatoid Arthritis (RA) and Systemic Lupus Erythematosus (SLE) because of its immunomodulatory effects. Previously, we have evaluated the genetic toxicology of different drugs and chemicals including antimalarial drug CQ both in vitro and in vivo. Thus, we recognize the need to critically review the mutagenic, genotoxic, and immunomodulatory effects of these drugs, to find out whether it is safe to use as a prophylactic drug against COVID-19. Existing literature suggests that CQ can induce mutagenic and genotoxic effects in multiple test systems and both the drugs have immunomodulatory effects. There was no data available to evaluate the mutagenicity and genotoxicity for HCQ. However, during metabolism about 60% of both the drugs remain unchanged and about 40% of the drugs are metabolized into two metabolites, desethylchloroquine and bisdesethylchloroquine by the action of the cytochrome P450 (CYP) enzymes in the liver. Both HCQ and CQ are immunomodulatory drugs and have the potential to suppress normal immune system activation. In this review, we have elucidated the mechanism of immunomodulation by both HCQ and CQ and highlighted the mutagenic and genotoxic effects from the available literature. This article is written with the sole objective that the reader will be able to recognize the adverse effects of these drugs when consumed by healthy individuals as a prophylactic. Current literature indicates that healthy individuals should refrain from the use of these drugs until further investigation.

Therapeutic vaccines for aggressive B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most common aggressive B-cell lymphoma and highly heterogeneous disease. With the standard immunochemotherapy, anti-CD20 antibody rituximab (R-) plus CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) chemotherapy, 30-40% of DLBCLs are refractory to initial immunochemotherapy or experience relapse post-therapy with poor clinical outcomes despite salvage therapies. Mechanisms underlying chemoresistance and relapse are heterogeneous across DLBCL and within individual patients, representing hurdles for targeted therapies targeting a specific oncogenic signaling pathway. In recent years, paradigm-shifting immunotherapies have shown impressive efficacy in various cancer types regardless of underlying oncogenic mechanisms. Vaccines are being developed for DLBCL to build protective immunity against relapse after first complete remission and to promote antitumor immune responses synergizing with immune checkpoint inhibitors to treat refractory/relapsed patients. This article provides a brief review of current progress in vaccine development in DLBCL and discussion on immunologic mechanisms underlying the therapeutic effectiveness and resistance.

Molecular mechanisms and epidemiology of COVID-19 from an allergist's perspective

The global pandemic caused by the newly described severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused worldwide suffering and death of unimaginable magnitude from coronavirus disease 2019 (COVID-19). The virus is transmitted through aerosol droplets, and causes severe acute respiratory syndrome. SARS-CoV-2 uses the receptor-binding domain of its spike protein S1 to attach to the host angiotensin-converting enzyme 2 receptor in lung and airway cells. Binding requires the help of another host protein, transmembrane protease serine S1 member 2. Several factors likely contribute to the efficient transmission of SARS-CoV-2. The receptor-binding domain of SARS-CoV-2 has a 10- to 20-fold higher receptor-binding capacity compared with previous pandemic coronaviruses. In addition, because asymptomatic persons infected with SARS-CoV-2 have high viral loads in their nasal secretions, they can silently and efficiently spread the disease. PCR-based tests have emerged as the criterion standard for the diagnosis of infection. Caution must be exercised in interpreting antibody-based tests because they have not yet been validated, and may give a false sense of security of being "immune" to SARS-CoV-2. We discuss how the development of some symptoms in allergic rhinitis can serve as clues for new-onset COVID-19. There are mixed reports that asthma is a risk factor for severe COVID-19, possibly due to differences in asthma endotypes. The rapid spread of COVID-19 has focused the efforts of scientists on repurposing existing Food and Drug Administration-approved drugs that inhibit viral entry, endocytosis, genome assembly, translation, and replication. Numerous clinical trials have been launched to identify effective treatments for COVID-19. Initial data from a placebo-controlled study suggest faster time to recovery in patients on remdesivir; it is now being evaluated in additional controlled studies. As discussed in this review, till effective vaccines and treatments emerge, it is important to understand the scientific rationale of pandemic-mitigation strategies such as wearing facemasks and social distancing, and implement them.

Hydroxychloroquine in rheumatic autoimmune disorders and beyond

Initially used as antimalarial drugs, hydroxychloroquine (HCQ) and, to a lesser extent, chloroquine (CQ) are currently being used to treat several diseases. Due to its cost‐effectiveness, safety and efficacy, HCQ is especially used in rheumatic autoimmune disorders (RADs), such as systemic lupus erythematosus, primary Sjögren's syndrome and rheumatoid arthritis. Despite this widespread use in the clinic, HCQ molecular modes of action are still not completely understood. By influencing several cellular pathways through different mechanisms, CQ and HCQ inhibit multiple endolysosomal functions, including autophagy, as well as endosomal Toll‐like receptor activation and calcium signalling. These effects alter several aspects of the immune system with the synergistic consequence of reducing pro‐inflammatory cytokine production and release, one of the most marked symptoms of RADs. Here, we review the current knowledge on the molecular modes of action of these drugs and the circumstances under which they trigger side effects. This is of particular importance as the therapeutic use of HCQ is expanding beyond the treatment of malaria and RADs.

Anti-DNA antibodies cross-reactive with β2-glycoprotein I induce monocyte tissue factor through the TLR9 pathway

Antibodies specific for cardiolipin (CL)-β₂-glycoprotein I (β₂GPI) are known to induce tissue factor (TF) expression by monocytes and endothelial cells which leads to a prothrombotic state in antiphospholipid syndrome (APS), but the mechanism is not fully elucidated. Previously, we reported that the mouse monoclonal anti-CL-β₂GPI antibody WB-6 cross-reacts with DNA, enters monocytes via binding to cell surface DNA, and induces TF expression. The current study aimed to identify the intracellular signaling pathways involved in this process. The binding of WB-6 to CL-β₂GPI or DNA, and endocytosis was not prevented by chloroquine, but pre-treatment of the cells with chloroquine significantly suppressed TF expression. TLR9 inhibitory oligodeoxynucleotide also suppressed the WB-6-induced TF expression, suggesting a pivotal role of the TLR9 pathway in TF production. Serum antibodies obtained from a patient with APS accompanying systemic lupus erythematosus (SLE) bound to both CL-β₂GPI and DNA, and induced TF in normal monocytes. This effect was suppressed by chloroquine, and abolished by removal of the DNA-binding activity. These results suggest that induction of TF expression results from TLR9 activation by DNA which was internalized together with cross-reactive antibodies produced in secondary APS accompanying SLE.

Cutaneous lupus erythematosus: The impact of self-amplifying innate and adaptive immune responses and future prospects of targeted therapies

Cutaneous lupus erythematosus (CLE) is a heterogeneous autoimmune disease encompassing a broad spectrum of skin conditions including localized plaques or widespread lesions, which may be accompanied by systemic involvement (systemic lupus erythematosus (SLE)). The disease is characterized by necroptotic keratinocytes and a cytotoxic immune cell infiltrate at the dermo-epidermal junction (DEJ), orchestrated by interferon (IFN)-regulated proinflammatory cytokines. Molecular analyses revealed a strong upregulation of innate and adaptive immune pathways in lesional skin including DNA-recognition pathways, chemokine signalling, antigen presentation and B- and T-cell activation, which are believed to interact in a complex self-amplifying network. Concerning adaptive immune signalling, particularly B cells are currently being studied as there is growing evidence for additional abilities besides autoantibody expression in skin autoimmunity. These detailed insights have paved the way for the development of drugs targeting crucial molecules of pathogenic immune cells and pathways. Moreover, they forwarded the understanding of distinct molecular mechanisms within CLE subtypes, which might enable a more mechanism-directed, stratified pharmacotherapy of LE skin lesions in the future.

Putative Natural History of CoViD-19

The Severe Acute Respiratory Syndrome Corona Virus2 (SARS-CoV2) is responsible for Corona Virus Disease 2019 (CoViD-19), the pandemic that has afflicted close to two million people worldwide, and has taken the lives of over 120,000 patients since its first report in late December 2019. Per million people globally, the infection rate is close to 250 with a death rate of close to 14 (death rate average global death rate: 6.06%; for comparison, revised estimate of the 1918 influenza pandemic had an average global death rate of 5.4% [1]). About 400,000 SARS-CoV2-positive patients have been declared 'recovered', although it is not clear to date what exactly that entails. To be clear, the natural history of SARS-CoV2 infection and of the patho-physiology of CoViD-19 remains shrouded in relative confusion, in part due to the exceedingly virulent nature of the virus, as manifest by its elevated morbidity and mortality, and the fast accumulation of clinical observations and research evidence. Many pieces of a complex puzzle are emerging all at once and their organization into a coherent and cogent picture of the natural history of CoViD-19 is arduous and still wanting. Here, we discuss the recent findings in the context of the available evidence. We propose a putative prediction model of the natural history of CoViD-19. We highlight putative loci and modes of therapeutic intervention that may become beneficial preventive and treatment modalities for individuals at risk of SARS-CoV2 infection and CoViD-19 patients.

Incident diabetes associated with hydroxychloroquine, methotrexate, biologics and glucocorticoids in rheumatoid arthritis: A systematic review and meta-analysis

OBJECTIVES

To evaluate the impact of disease-modifying antirheumatic drugs on the risk of developing diabetes in rheumatoid arthritis (RA) patients without diabetes.

METHODS

Electronic database searches of PubMed, EMBASE and Cochrane Library plus a hand search of conference proceedings were performed from inception to October 2019. The studies assessing the association between diabetes and antirheumatic agents in RA patients in cohort or case-control design were included. Data were pooled using fixed-effects or random-effects meta-analysis according to I² and pooled hazard ratios (HRs), and 95% confidence intervals (CIs) were used as summary statistic.

RESULTS

A total of 15 studies involving 552,019 patients with RA (11 for hydroxychloroquine, 7 for methotrexate, 6 for tumor necrosis factor inhibitors [TNFi], and 8 for glucocorticoids) were included. In pooled analysis, a reduced risk of diabetes was reported with hydroxychloroquine (meta-HR 0.61, 95% CI 0.56-0.66), methotrexate (meta-HR 0.81, 95% CI 0.75-0.87), TNFi (meta-HR 0.63, 95% CI 0.55-0.71), while glucocorticoids was associated with an increased risk of developing diabetes in a dose-dependent manner (Any dose: meta-HR 1.46, 95% CI 1.39-1.53; <10 mg/day prednisolone or equivalent: meta-HR 1.30, 95% CI 1.13-1.51; ≥10 mg/day prednisolone or equivalent: meta-HR 2.25, 95% CI 1.88-2.70).

CONCLUSIONS

Hydroxychloroquine, methotrexate and TNFi were associated with decreased risk of diabetes, and glucocorticoids with increased risk in RA patients. These important findings may aid clinical decision-making in the management of RA. Large, prospective, well-designed studies are needed in the RA patients with high-risk diabetes.

Toll-like receptor 9 expressed in proximal intestinal enteroendocrine cells detects bacteria resulting in secretion of cholecystokinin

Toll-like receptors (TLRs) play a key role in the recognition of microbes via detection of specific and conserved microbial molecular features. TLRs, mainly expressed in immune cells, interact with intestinal microbiome. Little is known about mechanism(s) of sensing of bacteria by the intestinal surface enteroendocrine cells (EECs). We show here that TLR9 is expressed by the EECs of proximal intestine in a range of species and is co-expressed with the satiety hormone cholecystokinin (CCK). CCK secreted in excess induces emesis (vomiting). Using an EEC model cell line, STC-1, we demonstrate that in response to the TLR9 agonist, DNA containing unmethylated CpG dinucleotide motifs, STC-1 cells secrete CCK and that this secretion is inhibited by specific inhibitors of TLR9. Exposure of STC-1 cells to heat-inactivated pathogenic bacteria, Escherichia coli O55/H7, Shigella flexneri 2457T, Salmonella typhimurium ST4/74, and non-pathogenic Lactobacillus amylovorus GRL1112, results to an increase in CCK secretion compared to untreated control. The magnitudes of CCK release are higher in response to pathogenic bacteria and lowest in response to the non-pathogenic L. amylovorus. The pathogenic strains not only have substantially bigger genomes than L. amylovorus, they also have significantly higher numbers/frequency of RR/CG/YY stimulatory CpG hexamers in their genomic DNA. Pathogen-induced excessive secretion of the gut hormone CCK, provoking emesis can serve as a protective mechanism against development of enteric infections.

Cutaneous Lupus Erythematosus: Progress and Challenges

PURPOSE OF REVIEW

The review provides an update on the diagnosis, pathogenesis, and treatment of cutaneous lupus erythematosus (CLE).

RECENT FINDINGS

Diagnostic challenges exist in better defining CLE as an independent disease distinct from systemic lupus erythematosus with cutaneous features and further classifying CLE based on clinical, histological, and laboratory features. Recent mechanistic studies revealed more genetic variations, environmental triggers, and immunologic dysfunctions that are associated with CLE. Drug induction specifically has emerged as one of the most important triggers for CLE. Treatment options include topical agents and systemic therapies, including newer biologics such as belimumab, rituximab, ustekinumab, anifrolumab, and BIIB059 that have shown good clinical efficacy in trials. CLE is a group of complex and heterogenous diseases. Future studies are warranted to better define CLE within the spectrum of lupus erythematosus. Better insight into the pathogenesis of CLE could facilitate the design of more targeted therapies.