Peripheral Lymphopenia Research Articles

PD-1 blockade synergizes with ascorbic acid to restore the activation and anti-viral immune functions of CD8+ T cells in a mouse model of BVDV infection

Bovine viral diarrhea virus (BVDV) can cause typical peripheral lymphopenia and inhibit CD8+ T-cell activation and proliferation. Programmed death-1 (PD-1) blockade has been shown to increase CD8+ T-cell activation during cytopathic (CP) BVDV infection but not non-cytopathic (NCP) BVDV. Notably, ascorbic acid (AA) restores lymphocyte count and activation during SARS-CoV-2 and influenza virus infections and has a synergistic effect with PD-1 blockade to improve antitumor CD8+ T-cell activity. Nevertheless, it remains unclear whether AA exerts an immunomodulatory effect on the activation and proliferation of CD8+ T cells during BVDV infection, especially NCP BVDV infection, or whether PD-1 blockade and AA exert a synergistic effect in regulating CD8+ T cell antiviral activities. In this study, we found that BVDV infection significantly decreased AA levels in serum and CD8+ T cells in a BALB/c mouse model. Interestingly, AA supplementation dramatically downregulated PD-1 expression, restored the activation and proliferation of CD8+ T cells, inhibited viral replication, ameliorated BVDV-induced histological lesions, and upregulated the expression of CD25 and p-ERK. More importantly, we also found a synergistic effect of PD-1 blockade with AA in restoring the activation and proliferation of CD8+ T cells during CP BVDV infection. However, during NCP BVDV infection, a synergistic effect of PD-1 blockade and AA led to the inhibition of viral replication and the promotion of IFN-γ production. Our findings provided new insights into the immunopathological mechanisms of BVDV and the potential value of anti-viral strategies based on AA treatment alone or in combination with PD-1 blockade.

CXCR4 antagonism ameliorates leukocyte abnormalities in a preclinical model of WHIM syndrome.

WHIM (Warts, Hypogammaglobulinemia, Infections, and Myelokathexis) syndrome is an ultra-rare, combined primary immunodeficiency and chronic neutropenic disorder characterized by a range of clinical presentations, including peripheral neutropenia, lymphopenia, and recurrent infections. WHIM syndrome is most often caused by gain-of-function mutations in the gene encoding C-X-C chemokine receptor 4 (CXCR4). As such, inhibition of CXCR4 with XOLREMDI® (mavorixafor), an orally bioavailable CXCR4 antagonist, demonstrated clinically meaningful increases in absolute neutrophil and lymphocyte counts and concomitant reduction in infections in patients with WHIM syndrome, resulting in its recent U.S. Food and Drug Administration approval. The impact of CXCR4 antagonism on other aspects of the pathobiology in WHIM syndrome, such as lymphopoiesis and leukocyte trafficking between primary and secondary lymphoid organs, is less understood. In the current study, the effects of CXCR4 antagonism on leukocyte trafficking and distribution in primary and secondary lymphoid organs were investigated in a mouse model of WHIM syndrome carrying the heterozygous Cxcr41013 mutation. Cxcr4+/1013 and Cxcr4 wild-type mice received the orally bioavailable CXCR4 antagonist X4-185. Blood, spleen and bone marrow samples were collected for numeration, flow cytometry, and functional studies. Cxcr4+/1013 mice exhibited profound peripheral blood leukopenia as seen in patients with WHIM syndrome. CXCR4 antagonism corrected circulating leukopenia and mobilized functional neutrophils without disrupting granulopoiesis in the bone marrow of Cxcr4+/1013 mice. Furthermore, Cxcr4+/1013 displayed aberrant splenic T and B-cell counts and frequency. Treatment with X4-185 normalized splenic T-cell abnormalities, correcting the reduced CD8+ T-cell numbers, restoring the CD4/CD8 T-cell ratio, and ameliorating peripheral blood T-cell lymphopenia. In addition, CXCR4 antagonism was able to correct the abnormal frequencies and numbers of splenic marginal zone and follicular B cells in Cxcr4+/1013 mice, and ultimately normalize B-cell lymphopenia in the peripheral circulation. Our study provides comprehensive evidence that oral dosing with a CXCR4 antagonist can effectively correct WHIM-associated neutrophil and lymphocyte abnormalities in a mouse model of WHIM syndrome. These findings extend our understanding of how targeting the dysregulated CXCR4 signaling pathway can ameliorate the pathogenesis of WHIM syndrome.

Cytokine Storm in Pathogenesis of COVID-19 Complications

The aim. To explore the current literature and key findings concerning the cytokine storm contribution to pathogenesis of COVID-19 complications and mortality, and summarize clinical and pathologic features of cytokine storm in COVID-19 patients. A cytokine storm is a hyperinflammatory state secondary to excessive production of cytokines by deregulated immune system. It manifests clinically as an influenza-like syndrome, which can be complicated by multi-organ failure and coagulopathy, leading in most severe cases even to death. Cytokine storm has recently emerged as key aspect in COVID-19 disease, as affected patients show high levels of several key pro-inflammatory cytokines, some of which also correlate with disease severity. The current review describes the role of critical cytokines in COVID-19-mediated cytokine storm. Key findings of the studies are provided further. A cytokine storm is associated with COVID-19 severity and is also a crucial cause of death from COVID-19. Impaired acquired immune responses and uncontrolled inflammatory innate responses may be associated with the mechanism of cytokine storm in COVID-19. Cytokine storm is defined as acute overproduction and uncontrolled release of pro-inflammatory markers, both locally and systemically. In COVID-19 patients, pyroptosis triggers the release of proinflammatory cytokines and affects macrophage and lymphocyte functions, causing peripheral lymphopenia. Cytokine storm is characterized by a clinical presentation of overwhelming systemic inflammation, hyperferritinemia, hemodynamic instability, and multi-organ failure. The cytokine storm clinical findings are attributed to the action of pro-inflammatory cytokines like interleukin-1, interleukin-6, tumor necrosis factor alpha, vascular endothelial growth factor.

Genetically-determined defects of T cell development.

Genetically determined defects of T-cell development comprise a heterogeneous group of conditions characterized by peripheral T-cell lymphopenia due to impaired intrathymic differentiation of T-cell progenitors. Collectively, these conditions are typically referred to as severe combined immune deficiency (SCID). In some cases (leaky SCID), residual function of the defective gene allows partial T-cell development. The vast majority of SCID disorders are due to genetic defects that affect the T-cell differentiation potential of hematopoietic stem cells, through a variety of mechanisms. However, some forms of SCID reflect impaired development or function of thymic stromal cells. A lack of peripheral T cells leads to increased susceptibility to severe infections since early in life. SCID is inevitably fatal unless immune reconstitution is achieved, most often through hematopoietic cell transplantation. Enzyme replacement therapy, gene therapy, and thymus implantation represent other forms of treatment in selected cases. The availability of newborn screening has greatly facilitated prompt recognition of SCID, which allows statistically significant improvement in survival after hematopoietic cell transplantation.

RIPK1 protects naive and regulatory T cells from TNFR1-induced apoptosis

The T cell population size is stringently controlled before, during, and after immune responses, as improper cell death regulation can result in autoimmunity and immunodeficiency. RIPK1 is an important regulator of peripheral T cell survival and homeostasis. However, whether different peripheral T cell subsets show a differential requirement for RIPK1 and which programmed cell death pathway they engage in vivo remains unclear. In this study, we demonstrate that conditional ablation of Ripk1 in conventional T cells (Ripk1ΔCD4) causes peripheral T cell lymphopenia, as witnessed by a profound loss of naive CD4+, naive CD8+, and FoxP3+ regulatory T cells. Interestingly, peripheral naive CD8+ T cells in Ripk1ΔCD4 mice appear to undergo a selective pressure to retain RIPK1 expression following activation. Mixed bone marrow chimeras revealed a competitive survival disadvantage for naive, effector, and memory T cells lacking RIPK1. Additionally, tamoxifen-induced deletion of RIPK1 in CD4-expressing cells in adult life confirmed the importance of RIPK1 in post-thymic survival of CD4+ T cells. Ripk1K45A mice showed no change in peripheral T cell subsets, demonstrating that the T cell lymphopenia was due to the scaffold function of RIPK1 rather than to its kinase activity. Enhanced numbers of Ripk1ΔCD4 naive T cells expressed the proliferation marker Ki-67+ despite the peripheral lymphopenia and single-cell RNA sequencing revealed T cell-specific transcriptomic alterations that were reverted by additional caspase-8 deficiency. Furthermore, Ripk1ΔCD4Casp8 ΔCD4 and Ripk1ΔCD4Tnfr1−/− double-knockout mice rescued the peripheral T cell lymphopenia, revealing that RIPK1-deficient naive CD4+ and CD8+ cells and FoxP3+ regulatory T cells specifically die from TNF- and caspase-8-mediated apoptosis in vivo. Altogether, our findings emphasize the essential role of RIPK1 as a scaffold in maintaining the peripheral T cell compartment and preventing TNFR1-induced apoptosis.

Histochemical Evidence for Reduced Immune Response in Nasal Mucosa of Patients with COVID-19.

The primary entry point of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the nasal mucosa, where viral-induced inflammation occurs. When the immune response fails against SARS-CoV-2, understanding the altered response becomes crucial. This study aimed to compare SARS-CoV-2 immunological responses in the olfactory and respiratory mucosa by focusing on epithelia and nerves. Between 2020 and 2022, we obtained post mortem tissues from the olfactory cleft from 10 patients with histologically intact olfactory epithelia (OE) who died with or from COVID-19, along with four age-matched controls. These tissues were subjected to immunohistochemical reactions using antibodies against T cell antigens CD3, CD8, CD68, and SARS spike protein for viral evidence. Deceased patients with COVID-19 exhibited peripheral lymphopenia accompanied by a local decrease in CD3+ cells in the OE. However, SARS-CoV-2 spike protein was sparsely detectable in the OE. With regard to the involvement of nerve fibers, the present analysis suggested that SARS-CoV-2 did not significantly alter the immune response in olfactory or trigeminal fibers. On the other hand, SARS spike protein was detectable in both nerves. In summary, the post mortem investigation demonstrated a decreased T cell response in patients with COVID-19 and signs of SARS-CoV-2 presence in olfactory and trigeminal fibers.

Sarcoidosis Masquerading as Miliary Tuberculosis: A Case Report

A miliary nodular pattern of the lungs is an unusual presentation of sarcoidosis. Diagnosis of this condition can be challenging and requires exclusion of other lung pathology. A 47-year-old African American male presented to his doctor with a complaint of unintentional weight loss, exertional dyspnea and cough. The patient had a history of chronic smoking as well as recent incarceration. A miliary nodular pattern was found on CT scan of the lungs in a random distribution (with prominent peri-lymphatic distribution). HIV was ruled out. Tuberculosis (TB) and fungal infections were ruled out by tissue specimens and cultures from bronchoalveolar washings. Non-caseating granulomas on tissue specimens, peripheral smear lymphopenia and an elevated angiotensin converting enzyme (ACE) level were the positive findings on pathology and labs. The patient responded to a tapering course of oral steroids. This case demonstrates one of the unusual clinical presentations of sarcoidosis. Sarcoidosis is an autoimmune condition with predilection for middle aged African American patients.

Influence of Splenomegaly and Splenectomy on the Immune Cell Profile of Patients with Common Variable Immunodeficiency Disease.

About 25% of patients with common variable immunodeficiency disease (CVID) have splenomegaly, necessitating sometimes splenectomy whom consequences on the immunological profile of CVID patients have never been studied. We analyzed 11 CVID patients' comprehensive blood immune cell phenotypes pre- and post-splenectomy. Flow cytometry analyses of immune cell populations. Among 89 CVID cohort patients, 41 with splenomegaly, splenomegaly was strongly associated with granulomatous disease, autoimmune disorders, lymphoid hyperplasia, and/or portal hypertension. CVID patients with splenomegaly have significant peripheral lymphopenia (p = 0.001), and significantly fewer peripheral class-switched memory B cells (smBs) (p = 0.001), CD4+ T lymphocytes (p = 0.001), NK (p = 0.0001) and dendritic cells (p ≤ 0.01), and significantly more circulating CD4+ and CD8+ (p = 0.00001) T cell subset activation (p = 0.00005), than CVID patients without splenomegaly. Examination of splenectomy impact on circulating lymphocyte subset distributions demonstrated the drastically enhanced total circulating lymphocyte count post-splenectomy, predominantly B lymphocytes and CD8+ T cells. However, splenectomy did not change B cell distribution, with smBs remaining persistently low, in contrast to complete inversion of the circulating T cell composition, with reversal of the CD4+/CD8+ ratio suggesting that amplification of the CD8+ T cell compartment is a CVID characteristic in patients with splenomegaly. Our results highlight this CD8+ amplification in CVID-splenomegaly patients that might be explained by a homing effect to the spleen and/or possible chronic virus replication, which in turn could induce T cell expansions. Splenectomizing CVID patients with splenomegaly restores the absolute circulating lymphocyte count, suggesting that the decreased T cell count in the presence of splenomegaly cannot be used as an exclusive criterion for combined immunodeficiency.

Anti-MDA5 antibody-positive dermatomyositis: pathogenesis and clinical progress.

Anti-melanoma differentiation-associated protein 5 (MDA5) antibody-positive dermatomyositis (MDA5-DM) is a subtype of dermatomyositis. Although the aetiology and pathology remain unclear, increasing evidence suggests that viral infection is a potential trigger of MDA5-DM. Multiple factors, including T cells, B cells, neutrophils and macrophages, are implicated in the pathophysiology of MDA5-DM. Distinctive skin rashes, rapidly progressive interstitial lung disease, peripheral lymphopenia and elevated serum ferritin levels are the most prominent clinical and laboratory features of MDA5-DM. Concomitant infection is a common complication of MDA5-DM. The proper evaluation of patients with MDA5-DM requires knowledge of the disease heterogeneity and clinical course variability. Several biomarkers, including serum levels of anti-MDA5 antibodies and biomarkers related to macrophage activation, have been identified as useful tools for monitoring disease activity and prognosis. MDA5-DM shows a poor response to conventional glucocorticoid and immunosuppressant therapy and has a poor overall prognosis. Therefore, there is an urgent need to explore the key pathogenic mechanisms of MDA5-DM and develop novel therapeutic options for patients. This Review discusses recent clinical progress and pathogenic findings of MDA5-DM.

Relapsing pericarditis: Peripheral blood neutrophilia, lymphopenia and high neutrophil-to-lymphocyte ratio herald acute attacks, high-grade inflammation, multiserosal involvement, and predict multiple recurrences.

To identify peripheral blood cellular correlates of active pericarditis and to verify whether peripheral blood neutrophils, lymphocytes and the neutrophil to-lymphocyte ratio (NLR) are associated with disease phenotype or prognosis. Observational prospective study on a cohort of 63 patients with idiopathic pericarditis followed for 12 months after each pericarditis recurrence. Two distinct analyses were performed: the "index attack" analysis focused on the first pericarditis episode in each patient, while the "all attacks" analysis included all episodes occurring during the study. Absolute and relative neutrophilia and lymphopenia, together with high NLR, were observed during active pericarditis, as compared with disease remission, at both analyses. Neutrophils showed a positive correlation with plasma C-reactive protein levels, while lymphocyte count showed a negative correlation. Relative neutrophil count was higher, and lymphocyte count lower in patients with pleural effusion; a higher NLR and lower absolute lymphocyte count were observed in those with peritoneal involvement. No correlations were found between peripheral blood neutrophil or lymphocyte counts and size of pericardial effusion, or with the presence of myocardial involvement. Peripheral neutrophilia, lymphopenia and NLR during acute attacks predicted the number of recurrences in the following 12 months. Peripheral blood neutrophilia and lymphopenia are typical of acute idiopathic pericarditis. Acute attacks of pericarditis are associated with neutrophilia and lymphopenia, as compared with disease remission. During acute attacks, neutrophilia and lymphopenia reflect the extent of serosal inflammation and could help to customize therapeutic management after remission has been achieved.

Impact of Siponimod on Enteric and Central Nervous System Pathology in Late-Stage Experimental Autoimmune Encephalomyelitis.

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS). Although immune modulation and suppression are effective during relapsing-remitting MS, secondary progressive MS (SPMS) requires neuroregenerative therapeutic options that act on the CNS. The sphingosine-1-phosphate receptor modulator siponimod is the only approved drug for SPMS. In the pivotal trial, siponimod reduced disease progression and brain atrophy compared with placebo. The enteric nervous system (ENS) was recently identified as an additional autoimmune target in MS. We investigated the effects of siponimod on the ENS and CNS in the experimental autoimmune encephalomyelitis model of MS. Mice with late-stage disease were treated with siponimod, fingolimod, or sham. The clinical disease was monitored daily, and treatment success was verified using mass spectrometry and flow cytometry, which revealed peripheral lymphopenia in siponimod- and fingolimod-treated mice. We evaluated the mRNA expression, ultrastructure, and histopathology of the ENS and CNS. Single-cell RNA sequencing revealed an upregulation of proinflammatory genes in spinal cord astrocytes and ependymal cells in siponimod-treated mice. However, differences in CNS and ENS histopathology and ultrastructural pathology between the treatment groups were absent. Thus, our data suggest that siponimod and fingolimod act on the peripheral immune system and do not have pronounced direct neuroprotective effects.

Circulating B-Cell Precursor Cells As Potential Diagnostic and Therapeutic Biomarker in Patients with WHIM Syndrome

Background Warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome is a combined immunodeficiency caused in most known cases by gain-of-function mutations in the CXCR4 gene. The wide spectrum of multisystem clinical presentations, often with incomplete penetrance and expressivity, can pose a diagnostic challenge. WHIM syndrome has historically been a clinicopathologic diagnosis, with myelokathexis being the pathognomonic feature of WHIM. As genetic testing is becoming readily available, sequencing of the CXCR4 gene is often used to confirm a clinical suspicion of WHIM syndrome by finding genetic variants. There is a need for additional easily accessible and noninvasive biomarkers for diagnosing WHIM syndrome. We hypothesize that B-cell compartment might also show pathognomonic features of WHIM syndrome. Patients and Methods We analyzed peripheral blood B-cell subsets in 13 patients diagnosed with WHIM syndrome from 8 families with pathogenic CXCR4 mutations using 9-multicolor flow cytometry after informed consent approval. Samples from 2 patients who received plerixafor were collected at baseline before and after treatment. The duration of treatment was approximately 6 months. Results Using multicolor flow cytometry, we analyzed circulating B-cell subsets (CD10,CD19,CD21,CD27,CD38,IgA,IgD,IgG and IgM) in 13 patients (pediatric, n=7; adult, n=6) with WHIM syndrome (9 patients with p.Arg334Stop mutation, 2 patients with p.Val320Glufs*23 mutation, 1 patient with p.Ser338Stop mutation, and 1 patient with p.Ser346Stop mutation). We observed severe peripheral B-cell lymphopenia, accompanied by the presence of a consistent and specific scarce CD19+CD10+CD38+IgM-IgD-CD21-CD27- B-cell subpopulation. A B-cell subpopulation with an equivalent marker expression pattern was not found in healthy controls (n=50) or in non-WHIM disease controls (n=20). The rare B-cell population found in WHIM syndrome was further characterized as belonging mostly to the pre-B-cell stage revealed by intracellular expression of IgM, CD179a (VpreB chain), and CD179b (lambda 5). The presence of these early B-cell precursors was independent of age and was stable over time in patients with WHIM syndrome. The number of these peripheral B-cell precursors found specifically in patients with WHIM syndrome was greatly reduced when the patients were treated with granulocyte colony-stimulating factor (G-CSF) or plerixafor; counts of the precursor cells returned to baseline after the patients discontinued plerixafor treatment. Conclusions Taken together, we identify a unique CD19+CD10+CD38+IgM-IgD-CD21-CD27- B-cell subpopulation in patients with WHIM syndrome that might be used as a noninvasive biomarker to help identify patients with this rare primary combined immunodeficiency. In addition, these circulating B-cell precursors may be used to monitor response to therapy in patients with WHIM syndrome. The observed impact of G-CSF on the B-cell precursor population may be attributed to downregulation of CXCL12/CXCR4, which influences myelokathexis and impairs egression of the precursor population from the bone marrow but needs further experimental validation.

NLRP3-Independent Inflammasome Activation By Proteasome Inhibitors

Introduction Proteasome inhibitors (PIs) such as Bortezomib (BTZ) have revolutionized multiple myeloma (MM) treatment. However, their efficacy is limited by the emergence of drug resistance and treatment-limiting side effects, including peripheral neuropathy and lymphopenia. Treatment resistance in MM has been demonstrated to be promoted by an NLRP3 inflammasome-mediated innate immune response to MM-associated proteins. Thus, we set out to investigate the impact of PI treatment on innate immune cytokine production. Materials and Methods The PIs BTZ, marizomib, epoxomicin and onx-0914 were applied to a variety of inflammasome-competent human immortalized and primary cells, including the cell line THP-1 (monocytic), primary human peripheral blood mononuclear cells (PBMC), M-CSF or ascites-derived macrophages, keratinocytes, and epithelial cells. Inflammasome activation was characterized via Interleukin-1b (IL-1β) release in cellular supernatants (ELISA, all cell types) and ASC-speck formation using an ASC-GFP reporter cell line (THP-1). To characterize the contribution of Nod-like receptor pyrin domain-containing protein 3 (NLRP3) and caspase-1 (CASP-1) to inflammasome formation, NLRP3 and CASP-1-deficient THP1 cells were generated using CRISPR/Cas9-mediated genome engineering, and NLRP3 and caspase-1 were pharmacologically inhibited using MCC-950 (Invitrogen) and VX-765 (Invivogen). Results We report PI-mediated activation of the inflammasome in all cells tested. Treatment with PI induced secretion of IL-1b by THP1 cells and PBMC with an EC50 that was similar to the IC50 in BTZ-sensitive, but not BTZ-resistant, KMS-11 MM cells. We observed hallmarks of canonical inflammasome activation such as the formation of ASC specks in PI-exposed cells. Moreover, pharmacological inhibition of caspase-1 with VX-765 or genetic caspase-1 deficiency abrogated IL-1b. A variety of inflammatory stimuli, including soluble proteins secreted by MM cells, induce inflammasome formation via activation of NLRP3, the only inflammasome receptor currently targetable by a small molecule and investigated in clinical trials. Surprisingly, neither genetic ablation of NLRP3 in THP-1 cells nor MCC-950 treatment of PBMC inhibited IL-1b signaling following BTZ exposure. Conclusion Here, we identify PIs as activators of the inflammasome. In contrast to previously identified myeloma-intrinsic mechanisms leading to inflammasome assembly, PI-mediated IL-1b secretion was independent of NLRP3. Further investigation will include the identification of the receptor mediating BTZ-driven inflammasome assembly in order to identify mechanisms of action that may be amenable to therapeutic intervention.

Altered transcription factor targeting is associated with differential peripheral blood mononuclear cell proportions in sarcoidosis.

IntroductionIn sarcoidosis, peripheral lymphopenia and anergy have been associated with increased inflammation and maladaptive immune activity, likely promoting development of chronic and progressive disease. However, the molecular mechanisms that lead to reduced lymphocyte proportions, particularly CD4+ T-cells, have not been fully elucidated. We posit that paradoxical peripheral lymphopenia is characterized by a dysregulated transcriptomic network associated with cell function and fate that results from altered transcription factor targeting activity.MethodsMessenger RNA-sequencing (mRNA-seq) was performed on peripheral blood mononuclear cells (PBMCs) from ACCESS study subjects with sarcoidosis and matched controls and findings validated on a sarcoidosis case-control cohort and a sarcoidosis case series. Preserved PBMC transcriptomic networks between case-control cohorts were assessed to establish cellular associations with gene modules and define regulatory targeting involved in sarcoidosis immune dysregulation utilizing weighted gene co-expression network analysis and differential transcription factor involvement analysis. Network centrality measures identified master transcriptional regulators of subnetworks related to cell proliferation and death. Predictive models of differential PBMC proportions constructed from ACCESS target gene expression corroborated the relationship between aberrant transcription factor regulatory activity and imputed and clinical PBMC populations in the validation cohorts.ResultsWe identified two unique and preserved gene modules significantly associated with sarcoidosis immune dysregulation. Strikingly, increased expression of a monocyte-driven, and not a lymphocyte-driven, gene module related to innate immunity and cell death was the best predictor of peripheral CD4+ T-cell proportions. Within the gene network of this monocyte-driven module, TLE3 and CBX8 were determined to be master regulators of the cell death subnetwork. A core gene signature of differentially over-expressed target genes of TLE3 and CBX8 involved in cellular communication and immune response regulation accurately predicted imputed and clinical monocyte expansion and CD4+ T-cell depletion.ConclusionsAltered transcriptional regulation associated with aberrant gene expression of a monocyte-driven transcriptional network likely influences lymphocyte function and survival. Although further investigation is warranted, this indicates that crosstalk between hyperactive monocytes and lymphocytes may instigate peripheral lymphopenia and underlie sarcoidosis immune dysregulation and pathogenesis. Future therapies selectively targeting master regulators, or their targets, may mitigate dysregulated immune processes in sarcoidosis and disease progression.

Excessive IL-10 and IL-18 trigger hemophagocytic lymphohistiocytosis–like hyperinflammation and enhanced myelopoiesis

Hyperinflammation is a life-threatening condition associated with various clinical disorders characterized by excessive immune activation and tissue damage. Multiple cytokines promote the development of hyperinflammation; however, the contribution of IL-10 remains unclear despite emerging speculations for a pathological role. Clinical observations from hemophagocytic lymphohistiocytosis (HLH), a prototypical hyperinflammatory disease, suggest that IL-18 and IL-10 may collectively promote the onset of a hyperinflammatory state. We aimed to investigate the collaborative roles of IL-10 and IL-18 in hyperinflammation. A comprehensive plasma cytokine profile for 87 secondary HLH patients was first depicted and analyzed. We then investigated the systemic and cellular effects of coelevated IL-10 and IL-18 in a transgenic mouse model and cultured macrophages. Single-cell RNA sequencing was performed on the monocytes/macrophages isolated from secondary HLH patients to explore the clinical relevance of IL-10/IL-18-mediated cellular signatures. The therapeutic efficacy of IL-10 blockade was tested in HLH mouse models. Excessive circulating IL-10 and IL-18 triggered a lethal hyperinflammatory disease recapitulating HLH-like phenotypes in mice, driving peripheral lymphopenia and a striking shift toward enhanced myelopoiesis in the bone marrow. IL-10 and IL-18 polarized cultured macrophages to a distinct proinflammatory state with pronounced expression of myeloid cell-recruiting chemokines. Transcriptional characterization suggested the IL-10/IL-18-mediated cellular features were clinically relevant with HLH, showing enhanced granzyme expression and proteasome activation in macrophages. IL-10 blockade protected against the lethal disease in HLH mouse models. Coelevated IL-10 and IL-18 are sufficient to drive HLH-like hyperinflammatory syndrome, and blocking IL-10 is protective in HLH models.

31P Efficacy and safety of utidelone in treatment-refractory advanced non-small cell lung cancer

Chemotherapy remains the standard-of-care for most patients with advanced NSCLC. Utidelone, a genetically engineered epothilone analogue, demonstrated marked and durable antitumor activity in patients with metastatic breast cancer. Here, we reported the efficacy and safety of utidelone for advanced NSCLC refractory to second-line treatment. This was an open label, multicenter, phase II study (NCT03693547). Eligible criteria included age 18-70, ECOG performance status of 0-1, failure of previous standard second-line treatment (including platinum-containing chemotherapy with or without targeted therapy). All patients received the recommended dose of utidelone (40mg/m2/d intravenously on d1-d5, 21d per cycle). The primary endpoint was objective response rate (ORR). Safety was analyzed in all patients who received at least one dose of study treatment. From April 22, 2019 to January 22, 2021, 26 patients were enrolled, with a median age of 55.3 (range 39-68) years. 61.5% of patients had an ECOG PS of 1, 80.8% had adenocarcinoma, and 65% were pre-treated with taxol. At baseline, pre-treatment in the second-line, third-line, and fourth-line or over were present in 34.6%, 38.5%, and 26.9%, respectively. Efficacy was evaluated in full analysis set (FAS) (n=26) and per protocol set (PPS) (n=21) with an ORR of 15.4% (95% CI 4.4, 34.9) and 19.0% (95% CI 5.4, 41.9), respectively. DCR were 69.2% (95% CI 48.2, 85.7) and 81.0% (95% CI 58.1, 94.6) in FAS and PPS, respectively. The median PFS was 4.37 (95% CI 2.50 5.29) months in FAS and 4.37 (95% CI 2.50, 9.76) months in PPS. OS was not reached but 12 month-OS rate was 69.0% (95% CI 45.1%, 84.1%) in FAS and 71.0% (95% CI 42.7%, 87.1%) in PPS. 26 (100%) patients had at least one adverse event (AE), 2 (7.7%) experienced discontinuation of utidelone and 8 (30.8%) had a dose reduction. Common grade 3-4 AEs were peripheral neuropathy (19.2%, all were grade 3), lymphopenia (7.7%), elevated glutamyltransferase (7.7%), and hyponatremia (7.7%). Notably, low incidences of liver and renal toxicities, and very limited gastrointestinal toxic effect were observed. These findings demonstrate that utidelone may be an effective treatment option for advanced NSCLC refractory to second-line treatment.

Cardiac Sarcoidosis with Peripheral Lymphopenia is Responsive to Adalimumab Therapy

Cardiac Sarcoidosis with Peripheral Lymphopenia is Responsive to Adalimumab Therapy

NSrp70 is a lymphocyte-essential splicing factor that controls thymocyte development.

Alternative pre-mRNA splicing is a critical step to generate multiple transcripts, thereby dramatically enlarging the proteomic diversity. Thus, a common feature of most alternative splicing factor knockout models is lethality. However, little is known about lineage-specific alternative splicing regulators in a physiological setting. Here, we report that NSrp70 is selectively expressed in developing thymocytes, highest at the double-positive (DP) stage. Global splicing and transcriptional profiling revealed that NSrp70 regulates the cell cycle and survival of thymocytes by controlling the alternative processing of various RNA splicing factors, including the oncogenic splicing factor SRSF1. A conditional-knockout of Nsrp1 (NSrp70-cKO) using CD4Cre developed severe defects in T cell maturation to single-positive thymocytes, due to insufficient T cell receptor (TCR) signaling and uncontrolled cell growth and death. Mice displayed severe peripheral lymphopenia and could not optimally control tumor growth. This study establishes a model to address the function of lymphoid-lineage-specific alternative splicing factor NSrp70 in a thymic T cell developmental pathway.

Mild COVID-19 Infection in a Patient with Multiple Sclerosis, while Taking Fingolimod: A Case Report

Background: Fingolimod, as an immunosuppressive drug, is used in the treatment of patients with Multiple Sclerosis. During recent pandemic, several controversies raised to stop or continue immunosuppressive drugs such as fingolimod in patients who developed coronavirus disease 2019. In this regard, most of consensuses advised to stop the consumption of this drug, but try to re-initiate before 6-8 weeks to prevent the disease’s activity or occurrence of rebound phenomenon. Case presentation: we report a 40-year old female patient with Multiple Sclerosis receiving fingolimod. Having peripheral lymphopenia, she developed coronavirus disease 2019 symptoms, tested for polymerase chain reaction of coronavirus, and the result was positive. Afterward, she stayed at home and did not stop fingolimod. However, her symptoms have improved and she did not need hospitalization for the entire course of coronavirus disease 2019 infection. Conclusion: The effects of the treatment with fingolimod on a patient infected by coronavirus disease 2019 are complex. On one hand, fingolimod withdrawal can increase the number of circulating lymphocytes, which consequently improves body defense against viral infections. On the other hand, it can also increase the risk of cytokine storm, which could be harmful. Therefore, further studies needed to find the risks and beneficial effects of fingolimod on coronavirus disease 2019 patients.

Calcium flux control by Pacs1-Wdr37 promotes lymphocyte quiescence and lymphoproliferative diseases.

Endoplasmic reticulum (ER) calcium (Ca2+ ) stores are critical to proteostasis, intracellular signaling, and cellular bioenergetics. Through forward genetic screening in mice, we identified two members of a new complex, Pacs1 and Wdr37, which are required for normal ER Ca2+ handling in lymphocytes. Deletion of Pacs1 or Wdr37 caused peripheral lymphopenia that was linked to blunted Ca2+ release from the ER after antigen receptor stimulation. Pacs1-deficient cells showed diminished inositol triphosphate receptor expression together with increased ER and oxidative stress. Mature Pacs1-/- B cells proliferated and died in vivo under lymphocyte replete conditions, indicating spontaneous loss of cellular quiescence. Disruption of Pacs1-Wdr37 did not diminish adaptive immune responses, but potently suppressed lymphoproliferative disease models by forcing loss of quiescence. Thus, Pacs1-Wdr37 plays a critical role in stabilizing lymphocyte populations through ER Ca2+ handling and presents a new target for lymphoproliferative disease therapy.