Differential down-regulation of HLA-DR on monocyte subpopulations during systemic inflammation

Causal relationship between OHSS and immune cells: A Mendelian randomization study

OBJECTIVE

To confirm the causal relationship between immune cells and Ovarian Hyperstimulation Syndrome.

DESIGN

Obtaining data, collecting single nucleotide polymorphisms, detecting instrumental variables heterogeneity, assessing causality, and assessing bidirectional causality.

SUBJECTS

A two sample Mendelian study to confirm the causal relationship between immune cells and Ovarian Hyperstimulation Syndrome.

EXPOSURE

Immune cell phenotype (including 22 million SNPs from GWAS on 3757 European individuals).

MAIN OUTCOME MEASURES

Inverse variance weighting, one-sample analysis, MR-Egger, weighted median and weighted mode are used to assess the causal relationship between 731 immunophenotypes and Ovarian Hyperstimulation Syndrome. The weighted median and Mendelian Randomization multi-effect residuals and Mendelian Randomization multi-effect residuals and outlier tests are used to assess bidirectional causality between this two.

RESULTS

After False Discovery Rate correction, 9 immunophenotypes were found to be significantly associated with the risk of Ovarian Hyperstimulation Syndrome. B cell panel: IgD+ AC (OR, 0.90) 、CD19 on CD24+ CD27+ (OR, 0.86) 、BAFF-R on CD20- CD38 (OR, -1.22); Mature T cell group panel: EM DN (CD4 -CD8-) AC (OR, 1.46); Myeloid cell panel: Mo MDSC AC (OR, 1.13) 、CD45 on CD33br HLA-DR+ (OR, 0.87); Monocyte panel: HLA-DR on monocyte (OR, 0.86) 、CCR2 on CD14+ CD16+ monocyte (OR, 1.15) 、cDC panel: HLA-DR on myeloid DC (OR, 0.89).

CONCLUSION

This study shows the potential link between OHSS and immune cells by genetic means, providing new ideas for future clinical and basic research.

Regulatory effects of microRNAs on monocytic HLA-DR surface expression

Decreased monocytic HLA-DR expression is the most studied biomarker of immune competency in critically ill and autoimmune disease patients. However, the underlying regulatory mechanisms remain largely unknown. One probable HLA-DR dysregulation is through microRNAs. The aim of this study was to investigate the effects of specific microRNAs on HLA-DR expression in human monocytic cells. Four up- and four down-HLA-DR-regulating microRNAs were identified, with hsa-miR-let-7f-2-3p showing the most significant upregulation and hsa-miR-567 and hsa-miR-3972 downregulation. Anti-inflammatory glucocorticoid medication Dexamethasone-decreased HLA-DR was significantly restored by hsa-miR-let-7f-2-3p and hsa-miR-5693. Contrarily, proinflammatory cytokines IFN-γ and TNF-α-increased HLA-DR were significantly reversed by hsa-miR-567. Clinically, paired plasma samples from patients before and one day after cardiac surgery revealed up-regulated expression of hsa-miR-5693, hsa-miR-567, and hsa-miR-3972, following the major surgical trauma. In silico approaches were applied for functional microRNA-mRNA interaction prediction and candidate target genes were confirmed by qPCR analysis. In conclusion, novel monocytic HLA-DR microRNA modulators were identified and validated in vitro. Moreover, both the interaction between the microRNAs and anti- and proinflammatory molecules and the up-regulated microRNAs identified in cardiac surgery highlight the potential clinical relevance of our findings.

Compartmentalization of the inflammatory response during bacterial sepsis and severe COVID-19

Acute infections cause local and systemic disorders which can lead in the most severe forms to multi-organ failure and eventually to death. The host response to infection encompasses a large spectrum of reactions with a concomitant activation of the so-called inflammatory response aimed at fighting the infectious agent and removing damaged tissues or cells, and the anti-inflammatory response aimed at controlling inflammation and initiating the healing process. Fine-tuning at the local and systemic levels is key to preventing local and remote injury due to immune system activation. Thus, during bacterial sepsis and Coronavirus disease 2019 (COVID-19), concomitant systemic and compartmentalized pro-inflammatory and compensatory anti-inflammatory responses are occurring. Immune cells (e.g., macrophages, neutrophils, natural killer cells, and T-lymphocytes), as well as endothelial cells, differ from one compartment to another and contribute to specific organ responses to sterile and microbial insult. Furthermore, tissue-specific microbiota influences the local and systemic response. A better understanding of the tissue-specific immune status, the organ immunity crosstalk, and the role of specific mediators during sepsis and COVID-19 can foster the development of more accurate biomarkers for better diagnosis and prognosis and help to define appropriate host-targeted treatments and vaccines in the context of precision medicine.

Monocyte HLA-DR level on admission predicting in-hospital mortality rate in exertional heatstroke: A 12-year retrospective study

BACKGROUND

Exertional heatstroke (EHS), a fatal illness, pronounces multiple organ dysfunction syndrome (MODS) and high mortality rate. Currently, no ideal factor prognoses EHS. Decreased monocyte human leukocyte-DR antigen (mHLA-DR) has been observed in critically ill individuals, particularly in those with sepsis. While most research focus on the pro-inflammatory response exploration in EHS, there are few studies related to immunosuppression, and no report targeted on mHLA-DR in EHS. The present study tried to explore the prognostic value of mHLA-DR levels in EHS patients.

METHODS

This was a single-center retrospective study. Clinical data of EHS patients admitted to the intensive care unit of the General Hospital of Southern Theatre Command between January 1, 2008, and December 31, 2020, were recorded and analyzed.

RESULTS

Seventy patients with 54 survivors and 16 nonsurvivors were ultimately enrolled. Levels of mHLA-DR in the nonsurvivors (41.8% [38.1-68.1]%) were significantly lower than those in the survivors (83.1% [67.6-89.4]%, p < 0.001). Multivariate logistic regression indicated that mHLA-DR (odds ratio [OR] = 0.939; 95% confidence interval [CI]: 0.892-0.988; p = 0.016) and Glasgow coma scale (GCS) scores (OR = 0.726; 95% CI: 0.591-0.892; p = 0.002) were independent risk factors related with in-hospital mortality rate in EHS. A nomogram incorporated mHLA-DR with GCS demonstrated excellent discrimination and calibration abilities. Compared to the traditional scoring systems, the prediction model incorporated mHLA-DR with GCS had the highest area under the curve (0.947, 95% CI: [0.865-0.986]) and Youden index (0.8333), with sensitivity of 100% and specificity of 83.33%, and a greater clinical net benefit.

CONCLUSION

Patients with EHS were at a risk of early experiencing decreased mHLA-DR early. A nomogram based on mHLA-DR with GCS was developed to facilitate early identification and timely treatment of individuals with potentially poor prognosis.

Monocytes as Targets for Immunomodulation by Regional Citrate Anticoagulation

Immune alterations in end-stage renal patients receiving hemodialysis are complex and predispose patients to infections. Anticoagulation may also play an immunomodulatory role in addition to the accumulation of uremic toxins and the effects of the dialysis procedure. Accordingly, it has been recently shown that the infection rate increases in patients under regional citrate anticoagulation (RCA) compared with systemic heparin anticoagulation (SHA). We hypothesized that RCA affects the immune status of hemodialysis patients by targeting monocytes. In a cohort of 38 end-stage renal patients undergoing hemodialysis, we demonstrated that whole blood monocytes of patients receiving RCA-but not SHA-failed to upregulate surface activation markers, like human leukocyte antigen class II (HLA-DR), after stressful insults, indicating a state of deactivation during and immediately after dialysis. Additionally, RNA sequencing (RNA-seq) data and gene set enrichment analysis of pre-dialysis monocytes evidenced a great and complex difference between the groups given that, in the RCA group, monocytes displayed a dramatic transcriptional change with increased expression of genes related to the cell cycle regulation, cellular metabolism, and cytokine signaling, compatible with the reprogramming of the immune response. Transcriptomic changes in pre-dialysis monocytes signalize the lasting nature of the RCA-related effects, suggesting that monocytes are affected even beyond the dialysis session. Furthermore, these findings demonstrate that RCA-but not SHA-impairs the response of monocytes to activation stimuli and alters the immune status of these patients with potential clinical implications.

Persistence of circulating CD169+monocytes and HLA-DR downregulation underline the immune response impairment in PASC individuals: the potential contribution of different COVID-19 pandemic waves

The use of CD169 as a marker of viral infection has been widely discussed in the context of COVID-19, and in particular, its crucial role in the early detection of SARS-CoV-2 infection and its association with the severity and clinical outcome of COVID-19 were demonstrated. COVID-19 patients show relevant systemic alteration and immunological dysfunction that persists in individuals with post-acute sequelae of SARS-CoV-2 infection (PASC). It is critical to implement the characterization of the disease, focusing also on the possible impact of the different COVID-19 waves and the consequent effects found after infection. On this basis, we evaluated by flow cytometry the expression of CD169 and HLA-DR on monocytes from COVID-19 patients and PASC individuals to better elucidate their involvement in immunological dysfunction, also evaluating the possible impact of different pandemic waves. The results confirm CD169 RMFI is a good marker of viral infection. Moreover, COVID-19 patients and PASC individuals showed high percentage of CD169+ monocytes, but low percentage of HLA-DR+ monocytes and the alteration of systemic inflammatory indices. We have also observed alterations of CD169 and HLA-DR expression and indices of inflammation upon different COVID-19 waves. The persistence of specific myeloid subpopulations suggests a role of CD169+ monocytes and HLA-DR in COVID-19 disease and chronic post-infection inflammation, opening new opportunities to evaluate the impact of specific pandemic waves on the immune response impairment and systemic alterations with the perspective to provide new tools to monitoring new variants and diseases associated to emerging respiratory viruses.

Abdominal surgery induces long-lasting changes in expression and binding of CTCF with impact on Major Histocompatibility Complex II transcription in circulating human monocytes

BACKGROUND

Postoperative immunosuppression has been recognized as an important driver of surgery-related morbidity and mortality. It is characterized by lymphocyte depression and impaired monocyte capability to present foreign antigens to T-cells via Major Histocompatibility Complex, Class II (MHC-II) molecules. In patients with postoperative abdominal sepsis, we previously detected a persisting differential binding of the CCCTC-Binding Factor (CTCF), a superordinate regulator of transcription, inside the MHC-II region with specific impact on human leucocyte antigen (HLA) gene expression. In this prospective exploratory study, we investigated to which extent major surgery affects the MHC-II region of circulating CD14+-monocytes.

RESULTS

In non-immunocompromised patients undergoing elective major abdominal surgery, a postoperative loss of monocyte HLA-DR surface receptor density was accompanied by a decline in the transcription levels of the classical MHC-II genes HLA-DRA, HLA-DRB1, HLA-DPA1 and HLA-DPB1. The surgical event decreased the expression of the transcriptional MHC-II regulators CIITA and CTCF and led to a lower CTCF enrichment at an intergenic sequence within the HLA-DR subregion. During the observation period, we found a slow and only incomplete restoration of monocyte HLA-DR surface receptor density as well as a partial recovery of CIITA, HLA-DRA and HLA-DRB1 expression. In contrast, transcription of HLA-DPA1, HLA-DPB1, CTCF and binding of CTCF within the MHC-II remained altered.

CONCLUSION

In circulating monocytes, major surgery does not globally affect MHC-II transcription but rather induces specific changes in the expression of selected HLA genes, followed by differential recovery patterns and accompanied by a prolonged reduction of CTCF expression and binding within the MHC-II region. Our results hint toward a long-lasting impact of a major surgical intervention on monocyte functionality, possibly mediated by epigenetic changes that endure the life span of the individual cell.

During Sepsis and COVID-19, the Pro-Inflammatory and Anti-Inflammatory Responses Are Concomitant

The most severe forms of COVID-19 share many features with bacterial sepsis and have thus been considered to be a viral sepsis. Innate immunity and inflammation are closely linked. While the immune response aims to get rid of the infectious agent, the pro-inflammatory host response can result in organ injury including acute respiratory distress syndrome. On its side, a compensatory anti-inflammatory response, aimed to dampen the inflammatory reaction, can lead to immunosuppression. Whether these two key events of the host inflammatory response are consecutive or concomitant has been regularly depicted in schemes. Initially proposed from 2001 to 2013 to be two consecutive steps, the concomitant occurrence has been supported since 2013, although it was proposed for the first time in 2001. Despite a consensus was reached, the two consecutive steps were still recently proposed for COVID-19. We discuss why the concomitance view could have been initiated as early as 1995.

Proinflammatory role of monocytes in SARS-CoV-2 infection in chronic hemodialysis patients

Background

Fully mature monocytes that express CD14, but not CD16, undergo phagocytosis within tissues, whereas non-classical monocytes, CD14-low CD16+, represent <11% of peripheral monocytes and have primary pro-inflammatory functions. Inflammation plays a major role in Covid-19 disease and adds to the inflammation caused by chronic hemodialysis. The aim of our study was to monitor monocyte subsets in five patients with end-stage kidney disease (ESKD) over a 1-year period after a mild Covid-19 infection. Five ESKD patients with a mild Covid-19 infection were monitored using CD14, CD16, CD300e, HLA-DR, CD64, and CD45 panels using a BD FACS Canto flow cytometer.

Results

CD14-low CD16+ was dramatically (p=0,001) decreased in patients during Covid-19 infection, as previously described for patients without chronic renal failure. In addition, CD14-low CD16+ monocytes remained decreased for 10 months after recovery from Covid. Intermediate monocytes increased during Covid-19 infection and decreased 10 months after infection but this subtype of monocytes retained their inflammatory activity with a significant increase in HLA-DR expression after recovery from Covid infection.

Conclusion

Our study shows that ESKD patients had a pro-inflammatory profile induced by Covid 19, but this status was prolonged significantly over a 10-month period. Thus, advanced renal failure treated by hemodialysis did not dramatically change the inflammatory response against to SARS Covid 2. It seems that monocytes retain their inflammatory status for many months in ESKD patients after a Covid-19 infection.

Parallel Dysregulated Immune Response in Severe Forms of COVID-19 and Bacterial Sepsis via Single-Cell Transcriptome Sequencing

Critically ill COVID-19 patients start developing single respiratory organ failure that often evolves into multiorgan failure. Understanding the immune mechanisms in severe forms of an infectious disease (either critical COVID-19 or bacterial septic shock) would help to achieve a better understanding of the patient’s clinical trajectories and the success of potential therapies. We hypothesized that a dysregulated immune response manifested by the abnormal activation of innate and adaptive immunity might be present depending on the severity of the clinical presentation in both COVID-19 and bacterial sepsis. We found that critically ill COVID-19 patients demonstrated a different clinical endotype that resulted in an inflammatory dysregulation in mild forms of the disease. Mild cases (COVID-19 and bacterial non severe sepsis) showed significant differences in the expression levels of CD8 naïve T cells, CD4 naïve T cells, and CD4 memory T cells. On the other hand, in the severe forms of infection (critical COVID-19 and bacterial septic shock), patients shared immune patterns with upregulated single-cell transcriptome sequencing at the following levels: B cells, monocyte classical, CD4 and CD8 naïve T cells, and natural killers. In conclusion, we identified significant gene expression differences according to the etiology of the infection (COVID-19 or bacterial sepsis) in the mild forms; however, in the severe forms (critical COVID-19 and bacterial septic shock), patients tended to share some of the same immune profiles related to adaptive and innate immune response. Severe forms of the infections were similar independent of the etiology. Our findings might promote the implementation of co-adjuvant therapies and interventions to avoid the development of severe forms of disease that are associated with high mortality rates worldwide.

Inflammatory status in pediatric sickle cell disease: Unravelling the role of immune cell subsets

Introduction: The mutation of the beta-globin gene that causes sickle cell disease (SCD) results in pleiotropic effects, such as hemolysis and vaso-occlusive crisis that can induce inflammatory mechanisms with deleterious consequences on the organism. Moreover, SCD patients display an increased susceptibility to infections. Few studies are currently available that evaluate a wide immunological profile in a pediatric population. This study proposes an evaluation of the immune profile in subjects with SCD in a pediatric population through a detailed analysis by flow cytometry. Methods and Materials: Peripheral blood samples from 53 pediatric patients with SCD (mean age 9.8 years, interquartile range 9 years) were obtained and then analyzed by flow cytometry, in order to evaluate changes in the immune populations compared to 40 healthy donors (mean age 7.3 years, interquartile range 9.5 years). Results: Our data showed an increase in neutrophils (with a reduction in the CD62L + subpopulation) and monocytes (with a decrease in HLA-DRlow monocytes) with normal values of lymphocytes in SCD patients. In the lymphocyte subpopulations analysis we observed lower values of CD4⁺ T cells (with higher number of memory and central memory T lymphocytes) with increased frequency of CD8⁺ T cells (with a predominant naive pattern). Moreover, we observed higher values of CD39⁺ Tregs and lower HLA-DR+ and CD39^- T cells with an increased Th17, Th1-17 and Th2 response. Conclusion: We observed immunological alterations typical of an inflammatory status (increase in activated neutrophils and monocytes) associated with a peculiar Treg pattern (probably linked to a body attempt to minimize inflammation intrinsic to SCD). Furthermore, we highlighted a T helper pathway associated with inflammation in line with other studies. Our data showed that immunological markers may have an important role in the understanding the pathophysiology of SCD and in optimizing targeted therapeutic strategies for each patient.

Targeting psychological stress-steroid-MARCH1 signaling pathway promotes the efficacy of specific allergen immunotherapy

Background: The therapeutic efficacy of allergen specific immunotherapy (SIT) is recognized, but needs improved. Psychological stress influences the immune system's function. The objective of this study is to elucidate the effects of psychological stress on compromising the effectiveness of SIT. Methods: A murine model with the airway allergic disorder (AAD) was established. Mice were treated with SIT with or without restraint stress (Rs). Results: Rs was found to significantly hamper the efficacy of SIT in mice with AAD. Induction of IL-10⁺ dendritic cells and type 1 regulatory T cells were reduced by Rs in the airway tissues. Rs-induced cortisol release subverted immune tolerance generation. Expression of MARCH1 was elevated in dendritic cells of the allergic lesion sites. The Rs-induced MARCH1 mediated the immune impairment in AAD mice. Genetic ablation of MARCH1 in dendritic cells efficiently blocked the Rs-compromised the therapeutic efficacy of SIT. Conclusion: Rs can increase the expression of MARCH1 in DCs of the allergic lesion sites. MARCH1 interferes with the immune regulatory properties in DCs, and impairs the immune regulatory capacity. Blocking MARCH1 can counteract the Rs-affected SIT efficacy.

Monocyte response after colorectal surgery: A prospective cohort study

BACKGROUND

Tumor resection is the common approach in patients with colorectal malignancy. Profound insight into inflammatory changes that accompany the normal post-operative stress response will establish reference parameters useful for identification of putative complications. Alterations in circulating monocytes might be indicative as these cells are considered to be the most responsive leukocytes to trauma. Therefore, the aim of this study is to assess the monocyte subset kinetic and phenotypic changes in response to surgery.

METHODS

Fifty patients undergoing colorectal tumor resection were included in a multicenter prospective cohort study. Blood samples were collected early in the morning prior to surgery and the next days through postoperative day three for flowcytometric analysis. Leukocyte subtypes were identified and expression of activation stage-related markers by monocyte subsets was quantified.

RESULTS

Changes in leukocyte subset composition and monocyte subset phenotypes were most prominent at the first day postoperatively, after which these parameters typically returned to normal or near-normal preoperative values. The immunophenotypic alterations after surgery were most notable in classical and intermediate monocytes. These included up-regulation of activation markers CD64 and CD62L, but down-regulation of HLA-DR and CD54. Markers of de-activation, CD163 and CD206, were consistently increasingly expressed.

DISCUSSION/CONCLUSION

The current study gives detailed insight into the peripheral blood leukocyte response after colorectal cancer surgery. This form of short-term stress induces a rapid and significant redistribution of immune cells. Immunophenotypic alterations in monocytes as a response to surgery suggest a mixed profile of cellular activation and de-activation.

Fatal COVID-19 is Associated with Reduced HLA-DR, CD123 or CD11c Expression on Circulating Dendritic Cells

Purpose

Severe coronavirus disease 2019 (COVID-19) is linked to insufficient control of viral replication and excessive inflammation driven by an unbalanced immune response. Plasmacytoid dendritic cells (pDCs) are specialized in the rapid production of interferons in response to viral infections, and can also prime and activate T-cells. Conventional DCs (cDCs) are critical for the elimination of viral infections owing to their specialized ability to prime and activate T cells. We assessed the frequency and phenotype of pDCs and cDCs in survivors and non-survivors of COVID-19.

Patients and methods

Patients with COVID-19 were enrolled, and 22 were included in this study. Peripheral whole blood was obtained during the 2^nd week of illness, stained with antibodies specific for lineage markers, human leukocyte antigen-DR isotype (HLA-DR), CD11c, and CD123, and analyzed by flow cytometry. Patients were followed-up during hospital admission and grouped into survivors (n=17) and non-survivors (n=5) of COVID-19.

Results

The ratio of pDCs to pre-cDCs was significantly lower (P=0.0005) in non-survivors compared to survivors. The frequency of pDCs was significantly higher than cDC2-like cells (P=0.0002) and pre-cDCs (P<0.0001) in survivors but not in non-survivors. HLA-DR expression level on pDCs and cDC2-like cells was lower in non-survivors compared to survivors (P=0.02 and P=0.058, respectively), and HLA-DR was inversely correlated with disease severity rating (pDCs: r= –0.47, P=0.027; cDC2-like cells: r= –0.45, P=0.037). CD123 expression level on pDCs was significantly lower (P=0.038) in non-survivors compared to survivors, and CD123 was inversely correlated with disease severity rating (r=–0.5, P=0.016). CD11c expression level on cDC2-like cells was significantly lower (P=0.03) in non-survivors compared to survivors, and CD11c was inversely correlated with disease severity rating (r=–0.47, P=0.025).

Conclusion

A lower frequency of pDCs compared to other circulating DCs, and lower expression levels of HLA-DR, CD123 or CD11c on DCs is associated with fatal COVID-19.

MHCII Expression on Peripheral Blood Monocytes in Canine Lymphoma: An Impact of Glucocorticoids

Simple Summary

Loss or decreased expression of human leukocyte antigen—D-related (HLA-DR) on the surface of monocytes is related to the dysfunction of the immune system and was reported in human neoplasia, including lymphoma. Canine lymphoma is frequently presented as a valuable comparative model for studies on human non-Hodgkin’s lymphoma. However, there are no studies on the expression of analogue proteins—MHCII antigens—on monocytes in canine lymphoma. In this study, we have evaluated the changes in the expression of MHCII on monocytes in the blood of dogs with lymphoma before any treatment and in dogs that had previously received glucocorticoids. Glucocorticoids are often used by clinicians as first drugs after diagnosis for immediate health improvement and are known to impact monocyte number. We have shown an increase in the percentage of MHCII− monocytes, regardless of treatment. However, only in dogs that had received glucocorticoids were changes in the proportion of MHCII+ and MHCII− monocytes reflected also by the changes in the number of MHCII− monocytes in the blood, which was significantly higher. Evaluating the changes in canine monocytes might be helpful in the diagnosis of various tumor types, monitoring of the treatment or assessing the immune status of dogs.

Abstract

An increase in the percentage of monocytes with reduced HLA-DR expression and immunosuppressive properties has been reported in numerous human neoplastic diseases, including lymphoma. However, there are no analogous studies on phenotypical variations in the peripheral blood monocytes in dogs with lymphoma. The aim of this study was to determine the difference in the expression of the MHCII molecule on peripheral blood monocytes in dogs with lymphoma before any treatment (NRG) and in dogs that had previously received glucocorticoids (RG) in comparison to healthy dogs. Flow cytometry immunophenotyping of peripheral blood leukocytes was performed using canine-specific or cross-reactive antibodies against CD11b, CD14 and MHCII. In the blood of dogs with lymphoma (NRG and RG), compared to that of healthy ones, the MHCII+ and MHCII− monocytes ratio was changed due to an increase in the percentage of MHCII− monocytes. The number of MHCII− monocytes was significantly higher only in RG dogs compared to healthy ones, which might result from the release of these cells from the blood marginal pool due to the action of glucocorticoids. Our results encourage further studies to assess if changes in MHCII expression affect immune status in dogs with lymphoma.

Monocyte Metabolism and Function in Patients Undergoing Cardiac Surgery

Objective

Cardiopulmonary bypass (CPB) can lead to systemic inflammation, which is associated with higher morbidity. Therefore, we investigated the metabolism of isolated blood monocytes before and after CPB compared to healthy controls.

Methods

In this prospective, monocentric, observational study, we included 30 patients undergoing CPB and 20 controls. We isolated monocytes from heparinized blood and investigated their metabolism by using Seahorse technology before (t0), 4 h (t4), and 24 h (t24) after the start of the CPB. We also examined programmed cell death 1 ligand (PD-L1), PD-L2, V-domain Ig suppressor of T cell activation (VISTA), and human leukocyte antigen-DR isotype (HLA-DR) using fluorescence-activated cell sorting analysis. Additionally, we investigated plasma cytokine levels in patients without and after ex vivo stimulation.

Results

CPB-induced inflammatory responses are shown by significantly elevated plasma interleukin-6 levels in the CPB group compared to baseline and controls [t0: 0 ng/ml (95%CI 0-0 ng/ml); t4: 0.16 ng/ml (95%CI 0.1-0.197 ng/ml), p < 0.0001; t24: 0.11 ng/ml (95% CI 0.1-0.16 ng/ml), p < 0.0001, and controls: 0 ng/ml (95% CI 0-0 ng/ml)]. The cytokine release in the ex vivo stimulation is reduced for lipopolysaccharide stimulation at t4 [t0: 35.68 ng/ml (95% CI 22.17-46.57 ng/ml) vs. t4: 15.02 (95% CI 10.25-24.78 ng/ml), p < 0.0001]. Intracellular metabolism of monocytes after CPB showed a protracted shift to aerobic glycolysis [t0: 179.2 pmol/min (95% CI 138.0-205.1 pmol/min) vs. t24: 250.1 pmol/min (95% CI 94.8-300.2 pmol/min), p < 0.0001]. Additionally, we observed an altered metabolism in monocytes in patients undergoing cardiac surgery compared to controls even before any surgical procedure [t0: 179.2 pmol/min (95% CI 138.0-205.1) vs. controls 97.4 (95% CI 59.13-144.6 pmol/min), p = 0.0031].

Conclusion

After CPB, patients' monocytes show a shift in metabolism from oxidative phosphorylation to aerobic glycolysis, which is associated with energy-demanding and proinflammatory processes. This is the first study to show changes in monocyte immunometabolism in cardiac surgery. Monocytes of patients undergoing cardiac surgery were leaning toward aerobic glycolysis even before any surgical procedure was conducted. Leaving the question of the pathophysiological mechanisms for future studies to be investigated and paving the way for potential therapy approaches preventing inflammatory effects of CPB.

Compartment-Specific Differences in the Activation of Monocyte Subpopulations Are Not Affected by Nitric Oxide and Glucocorticoid Treatment in a Model of Resuscitated Porcine Endotoxemic Shock

Inhaled nitric oxide (iNO) remains one of the treatment modalities in shock, and in addition to its vasoactive properties, iNO exerts immunomodulatory effects. We used a porcine model of endotoxemia with shock resuscitation (control) and additional treatment with iNO and a steroid (treatment group). After 20 h, bone marrow (BM), peripheral blood (PB), and bronchoalveolar lavage fluid (BALF) were collected to analyze the immunophenotype and mitochondrial membrane potential (Δφ) in three subsets of monocytes. In both groups, SLA-DR expression decreased twofold on the circulating CD14+CD163+ and CD14−CD163+ monocytes, while it did not change on the CD14+CD163+. Δφ increased only in the CD14−CD163+ subpopulation (0.8 vs. 2.0, p < 0.001). The analysis of compartment-specific alterations showed that nearly 100% of BALF CD14+CD163+ and CD14−CD163+ monocytes expressed SLA-DR, and it was higher compared to PB (32% and 20%, p < 0.0001) and BM (93% and 67%, p < 0.001, respectively) counterparts. BALF CD14+CD163+ had a threefold higher Δφ than PB and BM monocytes, while the Δφ of the other subsets was highest in PB monocytes. We confirmed the compartmentalization of the monocyte response during endotoxemic shock, which highlights the importance of studying tissue-resident cells in addition to their circulating counterparts. The iNO/steroid treatment did not further impair monocyte fitness.

Kinetics of human leukocyte antigen receptor HLA-DR+ monocytes and T lymphocytes during remission induction therapy in ANCA-associated vasculitis

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis is characterized by small vessel inflammation and the presence of autoantibodies against cytoplasmic proteases, most often proteinase-3 and myeloperoxidase. Peripheral blood monocytes are an important source of local macrophage accumulation within parenchymal organs, as evidenced by their presence in early lesions in ANCA-associated glomerulonephritis. Major histocompatibility complex (MHC) II cell surface receptor human leukocyte antigen receptor (HLA-DR) allows antigen presentation to T cells and is crucial for the initiation of an immune response. We herein report HLA-DR abundance in AAV and the kinetics of HLA-DR⁺ monocytes and T lymphocytes during remission induction therapy in AAV. Life-threatening AAV with pulmonary hemorrhage and renal involvement was associated with the presence of HLA-DR in a considerable population of peripheral blood monocytes and T lymphocytes, and relapsing disease manifested despite persistent B cell depletion after remission induction with rituximab. Moreover, remission induction in AAV with steroids, plasma exchange and intravenous cyclophosphamide, and improvement of clinical symptoms were associated with a decrease in HLA-DR⁺ differing between monocytes and T lymphocytes. Particularly, persistent suppression of HLA-DR⁺ monocytes was observed during remission induction, while an initial decrease in HLA-DR⁺ T lymphocytes was followed by recovery of this population during the further course. Detailed insights into HLA-DR kinetics could pave the way towards an increased understanding of immunopathology and identify patients that could mostly benefit from distinct remission induction regimens.

Monitoring Pre- and Post-Operative Immune Alterations in Patients With Locoregional Colorectal Cancer Who Underwent Laparoscopy by Single-Cell Mass Cytometry

Surgical excision is currently the principal therapy for locoregional colorectal cancer (CRC). However, surgical trauma leads to controlled tissue damage, causing profound alterations in host immunity and, in turn, affecting post-operative outcomes. Surgery-induced immune alterations in CRC remain poorly defined. Here, single-cell mass cytometry was applied to serial blood samples collected pre-operatively, and on days 1, 3, and 7 post-operatively from 24 patients who underwent laparoscopic surgical resection of CRC to comprehensively monitor the perioperative phenotypic alterations in immune cells and dynamics of immune response. Characterization of immune cell subsets revealed that the post-operative immune response is broad but predominantly suppressive, supported by the decreases in total frequencies of circulating T cells and natural killer (NK) cells, as well as decreased HLA-DR expression on circulating monocytes. The proportion of T cells significantly decreased on day 1 and recovered to the pre-surgical level on day 3 after surgery. The frequency of monocytes was significantly elevated on day 1 after surgery and declined to baseline level on day 3. NK cells temporarily contracted on post-operative day 3. T cells, monocytes, DCs, NK cells, and B cells were partitioned into phenotypically different single-cell clusters. The dynamics of single-cell clusters were different from those of the bulk lineages. T cell clusters in the same response phase fluctuate inconsistently during the perioperative period. Comparing to the baseline levels, the frequencies of CD11b(+)CD33(+)CD14(+)CD16(−) classical monocytes expanded followed by contraction, whereas CD11b(+)CD33(+)CD14(high)CD16(low) intermediate monocytes remained unchanged; HLA-DR expression in monocytes were significantly reduced; the frequencies of intermediate CD56(bright)CD16(+) NK cell subsets increased; and the percentage of memory B lymphocytes were elevated after surgery. Post-operative pro- and anti-inflammatory cytokines were both altered. Furthermore, perioperative immune perturbations in some of the cell subsets were unrecovered within seven days after surgery. Chronological monitoring major immune lineages provided an overview of surgery-caused alterations, including cell augments and contractions and precisely timed changes in immune cell distribution in both innate and adaptive compartments, providing evidence for the interaction between tumor resection and immune modulation.

Exosomes Recovered From the Plasma of COVID-19 Patients Expose SARS-CoV-2 Spike-Derived Fragments and Contribute to the Adaptive Immune Response

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by beta-coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that has rapidly spread across the globe starting from February 2020. It is well established that during viral infection, extracellular vesicles become delivery/presenting vectors of viral material. However, studies regarding extracellular vesicle function in COVID-19 pathology are still scanty. Here, we performed a comparative study on exosomes recovered from the plasma of either MILD or SEVERE COVID-19 patients. We show that although both types of vesicles efficiently display SARS-CoV-2 spike-derived peptides and carry immunomodulatory molecules, only those of MILD patients are capable of efficiently regulating antigen-specific CD4+ T-cell responses. Accordingly, by mass spectrometry, we show that the proteome of exosomes of MILD patients correlates with a proper functioning of the immune system, while that of SEVERE patients is associated with increased and chronic inflammation. Overall, we show that exosomes recovered from the plasma of COVID-19 patients possess SARS-CoV-2-derived protein material, have an active role in enhancing the immune response, and possess a cargo that reflects the pathological state of patients in the acute phase of the disease.

An Immunomodulatory Peptide Dendrimer Inspired from Glatiramer Acetate

Glatiramer acetate (GA) is a random polypeptide drug used to treat multiple sclerosis (MS), a chronic autoimmune disease. With the aim of identifying a precisely defined alternative to GA, we synthesized a library of peptide dendrimers with an amino acid composition similar to GA. We then challenged the dendrimers to trigger the release of the anti-inflammatory cytokine interleukin-1 receptor antagonist (IL-1Ra) from human monocytes, which is one of the effects of GA on immune cells. Several of the largest dendrimers tested were as active as GA. Detailed profiling of the best hit showed that this dendrimer induces the differentiation of monocytes towards an M2 (anti-inflammatory) state as GA does, however with a distinct immune marker profile. Our peptide dendrimer might serve as starting point to develop a well-defined immunomodulatory analog of GA.

Brazilian green propolis: A novel tool to improve the cytotoxic and immunomodulatory action of docetaxel on MCF-7 breast cancer cells and on women monocyte

Docetaxel (DTX) is used against breast cancer despite its side effects such as toxicity and immunosuppression. Here we investigated the cytotoxic and immunomodulatory effects of the ethanol solution extract of propolis (EEP) in combination with DTX on MCF-7 breast cancer cells and on women's monocyte. The cytotoxic potential of EEP + DTX was assessed by MTT assay and the type of tumor cell death was evaluated by flow cytometry. The effects of EEP + DTX on the migration and invasion of MCF-7 cells were analyzed. Cytokine production by monocytes was assessed by ELISA and the expression of cell surface markers was evaluated by flow cytometry. We also assessed the fungicidal activity of monocytes against Candida albicans and the generation of reactive oxygen species (ROS). Finally, the impact of the supernatants of treated monocytes in the viability, migration, and invasiveness of tumor cells was assessed. EEP enhanced the cytotoxicity of DTX alone against MCF-7 cells by inducing necrosis and inhibiting their migratory ability. EEP + DTX exerted no cytotoxic effects on monocytes and stimulated HLA-DR expression, TNF-α, and IL-6 production, exerted an immunorestorative action in the fungicidal activity, and reduced the oxidative stress. Our findings have practical implications and reveal new insights for complementary medicine.

TLR-4 Agonist Induces IFN-γ Production Selectively in Proinflammatory Human M1 Macrophages through the PI3K-mTOR- and JNK-MAPK-Activated p70S6K Pathway

IFN-γ, a proinflammatory cytokine produced primarily by T cells and NK cells, activates macrophages and engages mechanisms to control pathogens. Although there is evidence of IFN-γ production by murine macrophages, IFN-γ production by normal human macrophages and their subsets remains unknown. Herein, we show that human M1 macrophages generated by IFN-γ and IL-12- and IL-18-stimulated monocyte-derived macrophages (M0) produce significant levels of IFN-γ. Further stimulation of IL-12/IL-18-primed macrophages or M1 macrophages with agonists for TLR-2, TLR-3, or TLR-4 significantly enhanced IFN-γ production in contrast to the similarly stimulated M0, M2a, M2b, and M2c macrophages. Similarly, M1 macrophages generated from COVID-19-infected patients' macrophages produced IFN-γ that was enhanced following LPS stimulation. The inhibition of M1 differentiation by Jak inhibitors reversed LPS-induced IFN-γ production, suggesting that differentiation with IFN-γ plays a key role in IFN-γ induction. We subsequently investigated the signaling pathway(s) responsible for TLR-4-induced IFN-γ production in M1 macrophages. Our results show that TLR-4-induced IFN-γ production is regulated by the ribosomal protein S6 kinase (p70S6K) through the activation of PI3K, the mammalian target of rapamycin complex 1/2 (mTORC1/2), and the JNK MAPK pathways. These results suggest that M1-derived IFN-γ may play a key role in inflammation that may be augmented following bacterial/viral infections. Moreover, blocking the mTORC1/2, PI3K, and JNK MAPKs in macrophages may be of potential translational significance in preventing macrophage-mediated inflammatory diseases.

Resveratrol as an Adjunctive Therapy for Excessive Oxidative Stress in Aging COVID-19 Patients

The coronavirus disease 2019 (COVID-19) pandemic continues to burden healthcare systems worldwide. COVID-19 symptoms are highly heterogeneous, and the patient may be asymptomatic or may present with mild to severe or fatal symptoms. Factors, such as age, sex, and comorbidities, are key determinants of illness severity and progression. Aging is accompanied by multiple deficiencies in interferon production by dendritic cells or macrophages in response to viral infections, resulting in dysregulation of inflammatory immune responses and excess oxidative stress. Age-related dysregulation of immune function may cause a more obvious pathophysiological response to SARS-CoV-2 infection in elderly patients and may accelerate the risk of biological aging, even after recovery. For more favorable treatment outcomes, inhibiting viral replication and dampening inflammatory and oxidative responses before induction of an overt cytokine storm is crucial. Resveratrol is a potent antioxidant with antiviral activity. Herein, we describe the reasons for impaired interferon production, owing to aging, and the impact of aging on innate and adaptive immune responses to infection, which leads to inflammation distress and immunosuppression, thereby causing fulminant disease. Additionally, the molecular mechanism by which resveratrol could reverse a state of excessive basal inflammatory and oxidative stress and low antiviral immunity is discussed.

Meta-analysis of single-cell RNA-seq data reveals phenotypic switching of immune cells in severe COVID-19 patients

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has resulted in the global coronavirus disease 2019 (COVID-19) pandemic. Despite several single-cell RNA sequencing (RNA-seq) studies, conclusions cannot be reached owing to the small number of available samples and the differences in technology and tissue types used in the studies. To better understand the cellular landscape and disease severity in COVID-19, we performed a meta-analysis of publicly available single-cell RNA-seq data from peripheral blood and lung samples of COVID-19 patients with varying degrees of severity. Patients with severe disease showed increased numbers of M1 macrophages in lung tissue, while the number of M2 macrophages was depleted. Cellular profiling of the peripheral blood showed a marked increase of CD14⁺, CD16⁺ monocytes and a concomitant depletion of overall B cells and CD4⁺, CD8⁺ T cells in severe patients when compared with moderate patients. Our analysis indicates the presence of faulty innate-to-adaptive switching, marked by a prolonged innate immune response and a dysregulated adaptive immune response in severe COVID-19 patients. Furthermore, we identified cell types with a transcriptome signature that can be used as a prognostic biomarker for disease state prediction and the effective therapeutic management of COVID-19 patients.

Non-classical monocytes and its potential in diagnosing sepsis post cardiac surgery

BACKGROUND

Sepsis is caused by a dysregulation of immune response to infection that results in very high mortality. Current laboratory tests and clinical criteria are inadequate to diagnose sepsis due to limited sensitivity and specificity. Circulating monocytes are important players in immune homeostasis and their altered HLA-DR expression indicate immune dysregulation. HLA-DR is an MHC Class II cell-surface receptor that can present foreign antigens to helper T cells and mount an inflammatory response. Therefore, we analyzed the variations in HLA-DR expression and the concentration of monocyte subsets for diagnosing post-surgical sepsis.

METHODS

In this double-blinded prospective cohort study, we adopted immunophenotyping and quantification of antigen expression by flowcytometry to detect the changes in circulating monocyte subsets in patients undergoing cardiac surgery. Statistical analysis was performed to identify significant changes and based on the predictive potential of measured variables ROC curve analysis was done. ROC curve permitted the choice of appropriate cut-off values using which a diagnostic protocol was developed.

RESULTS

We observed that the monocyte subset concentrations in circulation varied differently after surgery. There was a significant downregulation of monocytic HLA-DR on both intermediate (p = 0.0477) and non-classical monocytes (p = 0.0333) at 48 h post-surgery. The monocyte subset analysis clearly showed that the patients with reduced pre-surgical non-classical monocyte count (p = 0.0430) coupled with post-surgical down-regulation of HLA-DR expression on the same subset had a higher incidence of developing sepsis after cardiac surgery.

CONCLUSIONS

Here we are reporting for the first time, the significant influence of non-classical monocytes in inducing dysregulated host response and sepsis after cardiac surgery. Using multiple biomarkers associated with this monocyte subset, we established an algorithm for the diagnosis of sepsis at 48 h post cardiac surgery with 100% sensitivity and 69.23% specificity.

Intraoperative Cell Salvage as an Alternative to Allogeneic (Donated) Blood Transfusion: A Prospective Observational Evaluation of the Immune Response Profile

Allogeneic blood transfusion (ABT) is associated with transfusion-related immune modulation (TRIM) and subsequent poorer patient outcomes including perioperative infection, multiple organ failure, and mortality. The precise mechanism(s) underlying TRIM remain largely unknown. During intraoperative cell salvage (ICS) a patient's own (autologous) blood is collected, anticoagulated, processed, and reinfused. One impediment to understanding the influence of the immune system on transfusion-related adverse outcomes has been the inability to characterize immune profile changes induced by blood transfusion, including ICS. Dendritic cells and monocytes play a central role in regulation of immune responses, and dysfunction may contribute to adverse outcomes. During a prospective observational study (n = 19), an in vitro model was used to assess dendritic cell and monocyte immune responses and the overall immune response following ABT or ICS exposure. Exposure to both ABT and ICS suppressed dendritic cell and monocyte function. This suppression was, however, significantly less marked following ICS. ICS presented an improved immune competence. This assessment of immune competence through the study of intracellular cytokine production, co-stimulatory and adhesion molecules expressed on dendritic cells and monocytes, and modulation of the overall leukocyte response may predict a reduction of adverse outcomes ( i.e., infection) following ICS.

Monocyte subset distribution and surface expression of HLA-DR and CD14 in patients after cardiopulmonary resuscitation

Systemic inflammation is a major feature of the post-cardiac arrest syndrome. The three monocyte subpopulations are thought to play an important role in this inflammatory state because they are endowed with numerous pattern recognition receptors, such as CD14, that have been associated with ischemia-reperfusion injury. By contrast, an exaggerated antiinflammatory response has also been described following cardiac arrest, which may be mediated by downregulation of antigen presentation receptor HLA-DR. We report the composition of monocyte subpopulations and the expression of CD14 and HLA-DR following cardiac arrest. Blood specimens were collected from 32 patients at three timepoints in the first 48 h after cardiac arrest. Monocyte subset composition was determined by flow cytometry based on the expression of CD14, CD16, and HLA-DR. Monocyte subset composition and the expression of CD14 and HLA-DR were correlated with patient outcomes. The results were compared to 19 patients with coronary artery disease. Cardiac arrest patients showed a significant decline in the percentage of nonclassical monocytes. Monocyte CD14 expression was upregulated after 24 h and correlated with the time to return of spontaneous circulation. Downregulation of HLA-DR expression was observed mainly among classical monocytes and significantly correlated with the dose of norepinephrine used to treat shock. Downregulation of HLA-DR among nonclassical and intermediate monocytes was significantly associated with disease severity. Our data demonstrate the disturbance of monocyte subset composition with a significant decline in nonclassical monocytes at an early stage following cardiac arrest. Our findings suggest the simultaneous presence of hyperinflammation, as evidenced by upregulation of CD14, and monocyte deactivation, characterized by downregulation of HLA-DR. The extent of monocyte deactivation was significantly correlated with disease severity.

The Many Faces of Innate Immunity in SARS-CoV-2 Infection

The innate immune system is important for initial antiviral response. SARS-CoV-2 can result in overactivity or suppression of the innate immune system. A dysregulated immune response is associated with poor outcomes; with patients having significant Neutrophil-to-Lymphocyte ratios (NLR) due to neutrophilia alongside lymphopenia. Elevated interleukin (IL)-6 and IL-8 leads to overactivity and is a prominent feature of severe COVID-19 patients. IL-6 can result in lymphopenia; where COVID-19 patients typically have significantly altered lymphocyte subsets. IL-8 attracts neutrophils; which may play a significant role in lung tissue damage with the formation of neutrophil extracellular traps leading to cytokine storm or acute respiratory distress syndrome. Several factors like pre-existing co-morbidities, genetic risks, viral pathogenicity, and therapeutic efficacy act as important modifiers of SARS-CoV-2 risks for disease through an interplay with innate host inflammatory responses. In this review, we discuss the role of the innate immune system at play with other important modifiers in SARS-CoV-2 infection.

The COVID-19 puzzle: deciphering pathophysiology and phenotypes of a new disease entity

The zoonotic SARS-CoV-2 virus that causes COVID-19 continues to spread worldwide, with devastating consequences. While the medical community has gained insight into the epidemiology of COVID-19, important questions remain about the clinical complexities and underlying mechanisms of disease phenotypes. Severe COVID-19 most commonly involves respiratory manifestations, although other systems are also affected, and acute disease is often followed by protracted complications. Such complex manifestations suggest that SARS-CoV-2 dysregulates the host response, triggering wide-ranging immuno-inflammatory, thrombotic, and parenchymal derangements. We review the intricacies of COVID-19 pathophysiology, its various phenotypes, and the anti-SARS-CoV-2 host response at the humoral and cellular levels. Some similarities exist between COVID-19 and respiratory failure of other origins, but evidence for many distinctive mechanistic features indicates that COVID-19 constitutes a new disease entity, with emerging data suggesting involvement of an endotheliopathy-centred pathophysiology. Further research, combining basic and clinical studies, is needed to advance understanding of pathophysiological mechanisms and to characterise immuno-inflammatory derangements across the range of phenotypes to enable optimum care for patients with COVID-19.

The Emerging World of Microbiome in Autoimmune Disorders: Opportunities and Challenges

Trillions of commensal bacteria colonizing humans (microbiome) have emerged as essential player(s) in human health. The alteration of the same has been linked with diseases including autoimmune disorders such as multiple sclerosis, rheumatoid arthritis, systemic lupus erythematosus, and ankylosing spondylitis. Gut bacteria are separated from the host through a physical barrier such as skin or gut epithelial lining. However, the perturbation in the healthy bacterial community (gut dysbiosis) can compromise gut barrier integrity, resulting in translocation of bacterial contents across the epithelial barrier (leaky gut). Bacterial contents such as lipopolysaccharide and bacterial antigens can induce a systemic inflammatory environment through activation and induction of immune cells. The biggest question in the field is whether inflammation causes gut dysbiosis or dysbiosis leads to disease induction or propagation, i.e., it is inside out or outside in or both. In this review, we first discuss the microbiome profiling studies in various autoimmune disorders, followed by a discussion of potential mechanisms through which microbiome is involved in the pathobiology of diseases. A better understanding of the role of the microbiome in health and disease will help us harness the power of commensal bacteria for the development of novel therapeutic agents to treat autoimmune disorders.

Selective killing of human M1 macrophages by Smac mimetics alone and M2 macrophages by Smac mimetics and caspase inhibition

The inflammatory and anti-inflammatory Mϕs have been implicated in many diseases including rheumatoid arthritis, multiple sclerosis, and leprosy. Recent studies suggest targeting Mϕ function and activation may represent a potential target to treat these diseases. Herein, we investigated the effect of second mitochondria-derived activator of caspases (SMAC) mimetics (SMs), the inhibitors of apoptosis (IAPs) proteins, on the killing of human pro- and anti-inflammatory Mϕ subsets. We have shown previously that human monocytes are highly susceptible whereas differentiated Mϕs (M0) are highly resistant to the cytocidal abilities of SMs. To determine whether human Mϕ subsets are resistant to the cytotoxic effects of SMs, we show that M1 Mϕs are highly susceptible to SM-induced cell death whereas M2a, M2b, and M2c differentiated subsets are resistant, with M2c being the most resistant. SM-induced cell death in M1 Mϕs was mediated by apoptosis as well as necroptosis, activated both extrinsic and intrinsic pathways of apoptosis, and was attributed to the IFN-γ-mediated differentiation. In contrast, M2c and M0 Mϕs experienced cell death through necroptosis following simultaneous blockage of the IAPs and the caspase pathways. Overall, the results suggest that survival of human Mϕs is critically linked to the activation of the IAPs pathways. Moreover, agents blocking the cellular IAP1/2 and/or caspases can be exploited therapeutically to address inflammation-related diseases.

Glucocorticoid-Induced Leucine Zipper: A Promising Marker for Monitoring and Treating Sepsis

Sepsis is a clinical syndrome that resulting from a dysregulated inflammatory response to infection that leads to organ dysfunction. The dysregulated inflammatory response transitions from a hyper-inflammatory phase to a hypo-inflammatory or immunosuppressive phase. Currently, no phase-specific molecular-based therapies are available for monitoring the complex immune response and treating sepsis due to individual variations in the timing and overlap of the dysregulated immune response in most patients. Glucocorticoid-induced leucine zipper (GILZ), is broadly present in multiple tissues and circumvent glucocorticoid resistance (GCR) or unwanted side effects. Recently, the characteristics of GILZ downregulation during acute hyperinflammation and GILZ upregulation during the immunosuppressive phase in various inflammatory diseases have been well documented, and the protective effects of GILZ have gained attention in the field of sepsis. However, whether GILZ could be a promising candidate biomarker for monitoring and treating septic patients remains unknown. Here, we discuss the effect of GILZ in sepsis and sepsis-induced immunosuppression.

Distinct inflammatory profiles distinguish COVID-19 from influenza with limited contributions from cytokine storm

We pursued a study of immune responses in coronavirus disease 2019 (COVID-19) and influenza patients. Compared to patients with influenza, patients with COVID-19 exhibited largely equivalent lymphocyte counts, fewer monocytes, and lower surface human leukocyte antigen (HLA)-class II expression on selected monocyte populations. Furthermore, decreased HLA-DR on intermediate monocytes predicted severe COVID-19 disease. In contrast to prevailing assumptions, very few (7 of 168) patients with COVID-19 exhibited cytokine profiles indicative of cytokine storm syndrome. After controlling for multiple factors including age and sample time point, patients with COVID-19 exhibited lower cytokine levels than patients with influenza. Up-regulation of IL-6, G-CSF, IL-1RA, and MCP1 predicted death in patients with COVID-19 but were not statistically higher than patients with influenza. Single-cell transcriptional profiling revealed profound suppression of interferon signaling among patients with COVID-19. When considered across the spectrum of peripheral immune profiles, patients with COVID-19 are less inflamed than patients with influenza.

A transient increase in MHC-IIlow monocytes after experimental infection with Avibacterium paragallinarum (serovar B-1) in SPF chickens

Infectious coryza (IC), an upper respiratory tract disease affecting chickens, is caused by Avibacterium paragallinarum. The clinical manifestations of IC include nasal discharge, facial swelling, and lacrimation. This acute disease results in high morbidity and low mortality, while the course of the disease is prolonged and mortality rates are increased in cases with secondary infections. Studies regarding the immune response in infected chickens are scarce, and the local immune response is the focal point of investigation. However, a large body of work has demonstrated that severe infections can impact the systemic immune response. The objective of this study was to evaluate the systemic effects of Avibacterium paragallinarum (serovar B-1) infection on immune cells in specific pathogen-free (SPF) chickens. The current study revealed the presence of a transient circulating monocyte population endowed with high phagocytic ability and clear downregulation of major histocompatibility complex class II (MHC-II) surface expression. In human and mouse studies, this monocyte population (identified as tolerant monocytes) has been correlated with a dysfunctional immune response, increasing the risk of secondary infections and mortality. Consistent with this dysfunctional immune response, we demonstrate that B cells from infected chickens produced fewer antibodies than those from control chickens. Moreover, T cells isolated from the peripheral blood of infected chickens had a lower ability to proliferate in response to concanavalin A than those isolated from control chickens. These findings could be related to the severe clinical signs observed in complicated IC caused by the presence of secondary infections.

Severe COVID-19 and aging: are monocytes the key?

The ongoing pandemic severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) causes a disproportionate number of severe cases and deaths in older adults. Severe SARS-CoV-2-associated disease (coronavirus disease 2019 (COVID-19)) was declared a pandemic by the World Health Organization in March 2020 and is characterized by cytokine storm, acute respiratory distress syndrome, and in some cases by systemic inflammation-related pathology. Currently, our knowledge of the determinants of severe COVID-19 is primarily observational. Here, I review emerging evidence to argue that monocytes, a circulating innate immune cell, are principal players in cytokine storm and associated pathologies in COVID-19. I also describe changes in monocyte function and phenotype that are characteristic of both aging and severe COVID-19, which suggests a potential mechanism underlying increased morbidity and mortality due to SARS-CoV-2 infection in older adults. The innate immune system is therefore a potentially important target for therapeutic treatment of COVID-19, but experimental studies are needed, and SARS-CoV-2 presents unique challenges for pre-clinical and mechanistic studies in vivo. The immediate establishment of colonies of SARS-CoV-2-susceptible animal models for aging studies, as well as strong collaborative efforts in the geroscience community, will be required in order to develop the therapies needed to combat severe COVID-19 in older adult populations.

Differential Accumulation and Activation of Monocyte and Dendritic Cell Subsets in Inflamed Synovial Fluid Discriminates Between Juvenile Idiopathic Arthritis and Septic Arthritis

Despite their distinct etiology, several lines of evidence suggest that innate immunity plays a pivotal role in both juvenile idiopathic arthritis (JIA) and septic arthritis (SA) pathophysiology. Indeed, monocytes and dendritic cells (DC) are involved in the first line of defense against pathogens and play a critical role in initiating and orchestrating the immune response. The aim of this study was to compare the number and phenotype of monocytes and DCs in peripheral blood (PB) and synovial fluid (SF) from patients with JIA and SA to identify specific cell subsets and activation markers associated with pathophysiological mechanisms and that could be used as biomarkers to discriminate both diseases. The proportion of intermediate and non-classical monocytes in the SF and PB, respectively, were significantly higher in JIA than in SA patients. In contrast the proportion of classical monocytes and their absolute numbers were higher in the SF from SA compared with JIA patients. Higher expression of CD64 on non-classical monocyte was observed in PB from SA compared with JIA patients. In SF, higher expression of CD64 on classical and intermediate monocyte as well as higher CD163 expression on intermediate monocytes was observed in SA compared with JIA patients. Moreover, whereas the number of conventional (cDC), plasmacytoid (pDC) and inflammatory (infDC) DCs was comparable between groups in PB, the number of CD141⁺ cDCs and CD123⁺ pDCs in the SF was significantly higher in JIA than in SA patients. CD14⁺ infDCs represented the major DC subset in the SF of both groups with potent activation assessed by high expression of HLA-DR and CD86 and significant up-regulation of HLA-DR expression in SA compared with JIA patients. Finally, higher activation of SF DC subsets was monitored in SA compared with JIA with significant up-regulation of CD86 and PDL2 expression on several DC subsets. Our results show the differential accumulation and activation of innate immune cells between septic and inflammatory arthritis. They strongly indicate that the relative high numbers of CD141⁺ cDC and CD123⁺ pDCs in SF are specific for JIA while the over-activation of DC and monocyte subsets is specific for SA.

Immunosuppression is Inappropriately Qualifying the Immune Status of Septic and SIRS Patients

Immunosuppression is the most commonly used concept to qualify the immune status of patients with either sterile systemic inflammatory response syndrome (SIRS) or sepsis. In this review we attempt to demonstrate that the concept of immunosuppression is an oversimplification of the complex anti-inflammatory response that occurs in patients dealing with a severe sterile or infectious insult. Particularly, the immune status of leukocytes varies greatly depending on the compartment from where they are derived from. Furthermore, although certain functions of immune cells present in the blood stream or in the hematopoietic organs can be significantly diminished, other functions are either unchanged or even enhanced. This juxtaposition illustrates that there is no global defect. The mechanisms called reprogramming or trained innate immunity are probably aimed at preventing a generalized deleterious inflammatory reaction, and work to maintain the defense mechanisms at their due levels.

In-depth immune cellular profiling reveals sex-specific associations with frailty

Background

With advancing age, the composition of leukocyte subpopulations in peripheral blood is known to change, but how this change differs between men and women and how it relates to frailty is poorly understood. Our aim in this exploratory study was to investigate whether frailty is associated with changes in immune cell subpopulations and whether this differs between men and women. Therefore, we performed in-depth immune cellular profiling by enumerating a total of 37 subpopulations of T cells, B cells, NK cells, monocytes, and neutrophils in peripheral blood of 289 elderly people between 60-87 years of age. Associations between frailty and each immune cell subpopulation were tested separately in men and women and were adjusted for age and CMV serostatus. In addition, a random forest algorithm was used to predict a participant’s frailty score based on enumeration of immune cell subpopulations.

Results

In the association study, frailty was found to be associated with increased numbers of neutrophils in both men and in women. Frailer women, but not men, showed higher numbers of total and CD16^- monocytes, and lower numbers of both CD56⁺ T cells and late differentiated CD4⁺ TemRA cells. The random forest algorithm confirmed all the findings of the association studies in men and women. In men, the predictive accuracy of the algorithm was too low (5.5%) to warrant additional conclusions on top of the ones derived from the association study. In women however, the predictive accuracy was higher (23.1%), additionally revealing that total T cell numbers and total lymphocyte numbers also contribute in predicting frailty.

Conclusions

In-depth immune cellular profiling revealed consistent associations of frailty with elevated numbers of myeloid cell subpopulations in both men and women. Furthermore, additional associations were found between frailty and lower numbers of some T cell subpopulations, in women only. Thus, our study indicates sex-specific associations of immune subpopulations with frailty. We hope that our study will prompt further investigation into the sex-specific immune mechanisms associated with the development of frailty.

Sepsis therapies: learning from 30 years of failure of translational research to propose new leads

Sepsis has been identified by the World Health Organization (WHO) as a global health priority. There has been a tremendous effort to decipher underlying mechanisms responsible for organ failure and death, and to develop new treatments. Despite saving thousands of animals over the last three decades in multiple preclinical studies, no new effective drug has emerged that has clearly improved patient outcomes. In the present review, we analyze the reasons for this failure, focusing on the inclusion of inappropriate patients and the use of irrelevant animal models. We advocate against repeating the same mistakes and propose changes to the research paradigm. We discuss the long-term consequences of surviving sepsis and, finally, list some putative approaches-both old and new-that could help save lives and improve survivorship.

Activation of α7 Nicotinic Acetylcholine Receptor Upregulates HLA-DR and Macrophage Receptors: Potential Role in Adaptive Immunity and in Preventing Immunosuppression

Immune response during sepsis is characterized by hyper-inflammation followed by immunosuppression. The crucial role of macrophages is well-known for both septic stages, since they are involved in immune homeostasis and inflammation, their dysfunction being implicated in immunosuppression. The cholinergic anti-inflammatory pathway mediated by macrophage α7 nicotinic acetylcholine receptor (nAChR) represents possible drug target. Although α7 nAChR activation on macrophages reduces the production of proinflammatory cytokines, the role of these receptors in immunological changes at the cellular level is not fully understood. Using α7 nAChR selective agonist PNU 282,987, we investigated the influence of α7 nAChR activation on the expression of cytokines and, for the first time, of the macrophage membrane markers: cluster of differentiation 14 (CD14), human leukocyte antigen-DR (HLA-DR), CD11b, and CD54. Application of PNU 282,987 to THP-1Mϕ (THP-1 derived macrophages) cells led to inward ion currents and Ca2+ increase in cytoplasm showing the presence of functionally active α7 nAChR. Production of cytokines tumor necrosis factor-α (TNF-α), interleukin (IL)-6, and IL-10 was estimated in classically activated macrophages (M1) and treatment with PNU 282,987 diminished IL-10 expression. α7 nAChR activation on THP-1Mϕ, THP-1M1, and monocyte-derived macrophages (MDMs) increased the expression of HLA-DR, CD54, and CD11b molecules, but decreased CD14 receptor expression, these effects being blocked by alpha (α)-bungarotoxin. Thus, PNU 282,987 enhances the macrophage-mediated immunity via α7 nAChR by regulating expression of their membrane receptors and of cytokines, both playing an important role in preventing immunosuppressive states.

Transportation and Routine Veterinary Interventions Alter Immune Function in the Dog

Rapid activation of the hypothalamic pituitary adrenal axis and the sympathetic nervous system are hallmarks of the acute stress response and these systems interact with the immune system by signaling though glucocorticoid and adrenergic receptors on immune cells. There is limited information about the effect of these physiologic responses on immunologic parameters of pet dogs enrolled in clinical studies. The objective of this study was to evaluate how travel, instrumentation, and hospitalization alter immunologic parameters in pet dogs. Blood was collected from healthy dogs in a home environment and from healthy dogs at the time of presentation to the hospital and after instrumentation and 24 hours of hospitalization. We found that lipopolysaccharide (LPS)-induced downregulation of toll like receptor 4 (TLR4) was blunted in dogs exposed to stress. Neutrophil and monocyte major histocompatibility complex class II (MHCII) expression increased after transportation to the veterinary hospital but then became similar to that of the control dogs at the end of hospitalization. Peripheral blood mononuclear cell cytotoxicity function was blunted in dogs exposed to the stress of transportation as well as hospitalization. Neutrophil apoptosis was greater in dogs exposed to stress compared to controls although this effect significantly decreased after hospitalization stress. Conversely, stress did not alter induced or spontaneous cytokine production from leukocytes, neutrophil or monocyte expression of TLR4, LPS-induced downregulation of monocyte TLR4, LPS-induced neutrophil and monocyte expression of MHCII or peripheral blood lymphocyte phenotype. Transportation and instrumentation/hospitalization stress should be considered when interpreting immunologic studies in pet dogs.

Changes in the Molecular and Functional Phenotype of Bovine Monocytes during Theileria parva Infection

Theileria parva is the causative agent of East Coast fever (ECF), a tick-borne disease that kills over a million cattle each year in sub-Saharan Africa. Immune protection against T. parva involves a CD8⁺ cytotoxic T cell response to parasite-infected cells. However, there is currently a paucity of knowledge regarding the role played by innate immune cells in ECF pathogenesis and T. parva control.

Theileria parva is the causative agent of East Coast fever (ECF), a tick-borne disease that kills over a million cattle each year in sub-Saharan Africa. Immune protection against T. parva involves a CD8⁺ cytotoxic T cell response to parasite-infected cells. However, there is currently a paucity of knowledge regarding the role played by innate immune cells in ECF pathogenesis and T. parva control. Here, we demonstrate an increase in intermediate monocytes (CD14⁺⁺ CD16⁺) with a concomitant decrease in the classical (CD14⁺⁺ CD16⁻) and nonclassical (CD14⁺ CD16⁺) subsets at 12 days postinfection (dpi) during lethal infection but not during nonlethal T. parva infection. Ex vivo analyses of monocytes demonstrated upregulation of interleukin-1 beta (IL-1β) and tumor necrosis factor alpha (TNF-α) mRNA and increased nitric oxide production during T. parva lethal infection compared to nonlethal infection at 10 dpi. Interestingly, no significant differences in peripheral blood parasite loads were observed between lethally and nonlethally infected animals at 12 dpi. In vitro stimulation with T. parva schizont-infected cells or Escherichia coli lipopolysaccharide (LPS) resulted in significant upregulation of IL-1β production by monocytes from lethally infected cattle compared to those from nonlethally infected animals. Strikingly, monocytes from lethally infected animals produced significant amounts of IL-10 mRNA after stimulation with T. parva schizont-infected cells. In conclusion, we demonstrate that T. parva infection leads to alterations in the molecular and functional phenotypes of bovine monocytes. Importantly, since these changes primarily occur in lethal infection, they can serve as biomarkers for ECF progression and severity, thereby aiding in the standardization of protection assessment for T. parva candidate vaccines.

Restoration of Peripheral Intermediate and Classical Monocytes Expressing HLA-DR in Patients With Lung Adenocarcinoma After Platinum-Based Chemotherapy

Lung adenocarcinoma represents one of the lung cancer subtypes with major prevalence. Accumulating evidence indicates that the immune system plays an important role in the evolution of the neoplastic process; additionally, several reports suggest that chemotherapy has an immunomodulatory effect. In order to identify the peripheral subpopulations of leukocytes that may change after chemotherapy, we evaluated several peripheral immune subpopulations of monocytes and lymphocytes by multicolor flow cytometry. In addition, we also measured cytokines and growth factors on plasma in order to evaluate the pro-inflammatory context in patients with lung adenocarcinoma after chemotherapy. We found that HLA-DR⁺ classical and intermediate monocytes were decreased in patients before chemotherapy, compared to controls. After chemotherapy, the relative percentage of those subpopulations was restored. In addition, interleukin 1β, interleukin 12, and interleukin 5 were increased after chemotherapy compared to prechemotherapy levels, while MIP-1β was decreased.

Post-operative immune suppression is mediated via reversible, Interleukin-10 dependent pathways in circulating monocytes following major abdominal surgery

Introduction

Post-operative infections occur frequently following major surgery. The magnitude of the post-operative immune response is associated with an increased risk of post-operative infections, although the mechanisms driving post-operative immune-dysfunction and the potential reversibility of this response with immune stimulants are not well understood. This study aims to describe the immediate immune response to major surgery and establish links to both post-operative infection and functional aspects of immune dysregulation. We also investigate the potential of clinically available immune stimulants to reverse features of post-operative immune-dysfunction.

Methods

Patients over 45 years old undergoing elective gastro-intestinal surgery with planned post-operative surgical ICU admission were recruited. The expression of selected genes was determined pre-operatively and at 2, 24 and 48 hours post-operatively using qRT-PCR. Circulating levels of Interleukin-10 protein were determined by ELISA. Peri-operative cell surface monocyte HLA-DR (mHLA-DR) expression was determined using flow cytometry. Gene expression and mHLA-DR levels were determined in healthy monocytes cultured in peri-operative serum with and without neutralising antibodies and immune stimulants.

Results

119 patients were recruited; 44 developed a post-operative infection. Interleukin-10 mRNA and protein increased 4-fold post-operatively (P<0.0001), peaking within 2 hours of the procedure. Higher post-operative Interleukin-10 mRNA (P = 0.007) and protein (P = 0.001) levels were associated with an increased risk of infection. Cell surface mHLA-DR expression fell post-operatively (P<0.0001). Reduced production, rather than intracellular sequestration, accounted for the post-operative decline in cell surface mHLA-DR expression. Interleukin-10 antibody prevented the decrease in mHLA-DR expression observed when post-operative serum was added to healthy monocytes. GM-CSF and IFN-γ prevented the decline in mHLA-DR production through distinct pathways.

Conclusions

Monocyte dysfunction and features of immune suppression occur frequently after major surgery. Greater post-operative Interleukin-10 production is associated with later infection. Interleukin-10 is an important mediator of post-operative reductions in mHLA-DR expression, while clinically available immune stimulants can restore mHLA-DR levels.