Peripheral Blood Leukocyte Populations Research Articles

Blood integrin- and cytokine-producing T cells are associated with stage and genetic risk score in age-related macular degeneration

Age-related macular degeneration (AMD) remains a leading cause of vision loss in the geriatric population. There are age-related changes in peripheral blood leukocyte composition, but their significance for AMD remains unclear. We aimed to determine changes in immune cell populations in the blood of AMD patients. A standardized 31-parameter flow cytometry analysis was conducted on peripheral blood mononuclear cells from 59 patients with early and advanced AMD and 39 controls without AMD, all older than 65 years. Fundus photography and optical coherence tomography were used to classify disease stages and a custom genotype array was used to compute an AMD genetic risk score based on 52 AMD disease risk variants (GRS-52). A generalized linear regression model corrected for age, sex, and smoking status revealed that AMD patients showed decreased frequencies of CD4+ T helper cell population expressing Integrin Alpha E (CD103) (Padj = 0.019). We further noted that early AMD was characterized by increased interleukin-4 (IL-4)-producing CD4+ T helper cells (Padj = 0.013; <0.001), as well as IL-4-producing cytotoxic CD8+ T cells (Padj = 0.016; <0.001). Reclassification of samples based on the GRS-52 revealed that IL-17-producing T cells decreased incrementally across GRS-52 categories. In AMD, alterations in peripheral blood leukocyte populations are associated with genetic risk score and disease stage and include specifically IL-4 and IL-17A cytokine-producing and CD103 integrin-expressing T cell populations.

The Effect of Probiotics in a Milk Replacer on Leukocyte Differential Counts, Phenotype, and Function in Neonatal Dairy Calves.

Probiotics have been investigated for many health benefits; however, few studies have been performed to determine the effects of oral probiotics on peripheral blood and respiratory immune cells in cattle. Our objectives were to determine changes in health and growth status, differential blood cell counts and function, and blood and lung cell function using flow cytometry and PCR in dairy calves fed a milk replacer with (PRO, N = 10) or without (CON, N = 10) the addition of probiotics to the milk replacer and dry rations from birth to weaning. Performance and clinical scores were not different between the treatment groups. Treatment-by-day interactions for peripheral blood leukocyte populations differed in cell number and percentages. A greater percentage of leukocytes expressed the cell surface markers CD3, CD4, CD8, CD11b, and CD205 on d 21 in CON animals. Lung lavages were performed on five animals from each treatment group on d 52. There were no differences between treatment groups for the expression of cytokines and Toll-Like Receptors as measured using Polymerase Chain Reaction, possibly due to the small sample size. Oral probiotics appear to affect peripheral blood immune cells and function. Their effect on overall calf health remains to be determined.

Sex-specific and immune-cell-specific contributions of beta2 integrins in myocardial ischemia-reperfusion injury

Leukocyte recruitment and their mediated inflammatory responses are critical for cardiovascular diseases, including myocardial ischemia-reperfusion (I/R) injury, which accounts for 9% mortality and 10% morbidity rates in ischemic heart disease patients. Blocking leukocyte recruitment in mouse knockouts (KO) of beta2 integrin (CD18) or blocking beta2 integrin with anitibodies in multiple animals significantly reduced infarct size after myocardial I/R injury. However, the cell-specific contribution of leukocyte beta2 integrin to I/R injury is unknown. In this study, we used the newly established CD18flox/flox (hITGB2 KI) mouse strain to address this knowledge gap. We crossed them to CSF1R-cre (CD115) and MRP8-cre (S100A8) and tested the KO of beta2 integrins in different leukocyte populations. Interestingly, CSF1R-cre CD18flox/flox unexpectedly deleted beta2 integrins in all peripheral blood leukocyte populations, including blood neutrophils, monocytes, CD4 T cells, CD8 T cells, B cells, and NK cells. It also elevated the cell number of these leukocyte populations in peripheral blood. In MRP8-cre CD18flox/flox mice, beta2 integrins were only knocked out in neutrophils but not other peripheral blood leukocytes. And only neutrophil number was elevated in peripheral blood. After 35 minutes of myocardial ischemia and 24 hours of reperfusion, we found both CSF1R-cre CD18flox/flox and MRP8-cre CD18flox/flox mice have significantly reduced infarct size compared to cre- controls. However, if we distinguish the sex in analysis, we only found a significant alleviation in female but not male CSF1R-cre CD18flox/flox mice. In contrast, we observed a significant alleviation only in male but not female MRP8-cre CD18flox/flox mice. These results suggested sex-specific and immune-cell-specific contributions of beta2 integrins in myocardial ischemia-reperfusion injury and provided new insights into beta2 integrin targeting therapies. This research was supported by grants from the National Institutes of Health, National Heart, Lung, and Blood Institute, USA (R01HL145454, R41HL156322, and R44HL152710) and a startup fund from UConn Health. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Peripheral blood immune cell profiling in survivors of testicular germ cell tumors.

417 Background: Testicular germ cell tumors (GCT) achieve exceptional cure rate with cisplatin-based chemotherapy. Survivors of GCTs represent a unique population to study post-cancer treatment physiology and late toxicities. The impact of cancer treatment on the immune-cell profile in long-term GCT survivors is unknown. In this study, we performed an immune-phenotyping in survivors of GCTs. Methods: Whole peripheral blood was obtained from GCT survivors (N = 202) at National Cancer Institute of Slovakia within the protocol of the ongoing survivorship study on a day of their annual follow-up visit. The median follow-up was 11 years (2-25). GCT survivors were distributed into treatment groups: RT – radiotherapy to the retroperitoneum (N = 18), CT - chemotherapy (N = 143), CTRT - chemotherapy + radiotherapy (N=9); and a control group: AS - active surveillance/orchiectomy only (N=32). Immuno-phenotyping of peripheral blood leukocyte populations was performed with flow-cytometry. Immune cell subpopulations were statistically assessed for associations with received treatment. Results: Survivors treated with RT vs AS had higher no of classical dendritic cells (DCs) (mean ± SEM = 82.0 ± 1.9 vs 76.5 ±1.5, p = 0.03) and non-significantly lower no of plasmacytoid DCs and CD16+ DCs (0.11 ± 0.01 vs 0.15 ± 0.01, p = 0.06 and 54.4 ± 4.1 vs 64.8 ± 3.2, p = 0.07, respectively). Survivors treated with CT vs AS had higher no of CD19+ B cells (11.9 ± 0.3 vs 10.4 ± 0.7, p = 0.04)and lower no of CD8+ T cells (26.0 ± 1.3 vs 23.7 ± 0.6, p = 0.04). Similarly, survivors treated with CTRT vs AS had higher no of CD19+ B cells (13.6 ± 1.4 vs 10.4 ± 0.7, p = 0.04) and lower no of CD8+ T cells (20.7 ± 2.4 vs 26.0 ± 1.3, p = 0.04). Survivors treated with ≥ 400mg/m2 of cisplatin-based chemotherapy vs AS had no of CD19+ B cells (12.2 ± 0.5 vs 10.4 ± 0.7, p = 0.04) and lower no of CD8+ T cells (23.4 ± 0.9 vs 26.3 ±1.3, p = 0.04). The immunoregulatory index CD4/CD8 was higher in CTRT vs AS (2.5 ± 0.3 vs 1.8 ± 0.1, p = 0.04). Conclusions: Certain subpopulations of leukocytes differ according to received treatment in survivors of GCTs. Our results may suggest that chemotherapy and/or radiotherapy may produce long-term immunomodulatory effects. Interplay between B and T cells may be a contributing mechanism of late toxicities. Further research is needed to uncover the causal relationship to the long-term health of GCT survivors.

Hypofractionated vs. Conventionally Fractionated Radiotherapy for Glioblastoma: Peripheral Blood Leukocyte Comparison prior to and Following Chemoradiation

<h3>Purpose/Objective(s)</h3> The diagnosis of glioblastoma portends a poor prognosis with extremely low 5-year survival rates. Immune suppression related to the tumor, radiotherapy (RT), and chemotherapy has been documented following treatment and appears associated with poor tumor outcome. Previous study suggests radiotherapy contributes to lymphopenia, and that a shorter course of treatment may better spare the lymphocyte population. However, immunosuppressive monocytes, such as myeloid-derived suppressor cells, expand in number during treatment and may also affect tumor control directly and by contributing to lymphopenia. We analyzed clinical measures of peripheral blood leukocytes in patients receiving conventionally fractionated (CF) RT and hypofractionated (HF) RT for glioblastoma. We hypothesized monocyte quantities expand more with CF RT, compared to HF RT following concurrent chemoradiation. <h3>Materials/Methods</h3> We retrospectively reviewed records from patients treated for diagnosis of glioblastoma between 7/1/2011 and 6/2/2021 at our institution. Patients over the age of 18 who completed their glioblastoma RT course, had not received prior RT, and had sufficient lab data for comparison were included. Clinical peripheral blood counts were recorded prior to and following chemoradiation. Values were analyzed using descriptive summary statistics and t-confidence intervals. CF RT for newly diagnosed glioblastoma usually consists of approximately 6000 centigray (cGy) in 30 fractions. HF RT schemes used were generally 3400-4500 cGy in 10-15 fractions. <h3>Results</h3> Lab results from 80 patients (65 CF, 15 HF) were analyzed prior to and following RT. The median patient age was 59 years (Q1, Q3: 47, 66). 57% were male. All patients received concurrent temozolomide. Absolute leukocyte count decreased by 4.8 10⁹/L (3.7, 5.9) and 1.9 10⁹/L (-0.1, 3.8) for CF RT and HF RT, respectively. Absolute lymphocytes decreased by 7.0 10⁹/L (5.8, 8.1) in CF RT and 5.3 10⁹/L (3.5, 7.1) in HF RT, while the percent lymphocytes increased by 1.1% (-1.8%, 4.1%) for CF RT and 2.1% (-3.9%, 8.0%) for HF RT, respectively. Absolute monocytes decreased by 0.1 10⁹/L (0.0, 0.2) for CF RT and 0.1 10⁹/L (-0.1, 0.3) for HF RT. The percent monocytes increased by 2.7% (1.3%, 4.1%) in CF RT and by 0.2% (-2.2%, 2.6%) in HF RT. <h3>Conclusion</h3> We observed different effects in peripheral blood leukocyte populations in glioblastoma patients receiving CF RT and HF RT. Percent monocytes had the greatest increase of the white blood cell types in CF RT, while percent lymphocytes had the greatest increase after concurrent chemoradiation in those receiving HF RT. Further study will better define the effects of RT on the various cell populations important for anti-neoplastic immunity and assess impact on survival.

Myeloid cell-specific mutation of Spi1 selectively reduces M2-biased macrophage numbers in skeletal muscle, reduces age-related muscle fibrosis and prevents sarcopenia.

Intramuscular macrophages play key regulatory roles in determining the response of skeletal muscle to injury and disease. Recent investigations showed that the numbers and phenotype of intramuscular macrophages change during aging, suggesting that those changes could influence the aging process. We tested that hypothesis by generating a mouse model that harbors a myeloid cell‐specific mutation of Spi1, which is a transcription factor that is essential for myeloid cell development. The mutation reduced the numbers of macrophages biased to the CD163+/CD206+ M2 phenotype in muscles of aging mice without affecting the numbers of CD68‐expressing macrophages and reduced the expression of transcripts associated with the M2‐biased phenotype. The mutation did not affect the colony‐forming ability or the frequency of specific subpopulations of bone marrow hematopoietic cells and did not affect myeloid/lymphoid cell ratios in peripheral blood leukocyte populations. Cellularity of most myeloid lineage cells was not influenced by the mutation. The Spi1 mutation in bone marrow‐derived macrophages in vitro also did not affect expression of transcripts that indicate the M2‐biased phenotype. Thus, myeloid cell‐targeted mutation of Spi1 influences macrophage phenotype in muscle but did not affect earlier stages of differentiation of cells in the macrophage lineage. The mutation reduced age‐related muscle fibrosis, which is consistent with the reduction of M2‐biased macrophages, and reduced expression of the pro‐fibrotic enzyme arginase. Most importantly, the mutation prevented sarcopenia. Together, our observations indicate that intramuscular, M2‐biased macrophages play significant roles in promoting detrimental, age‐related changes in muscle.

Single-Cell Analysis of the In Vivo Dynamics of Host Circulating Immune Cells Highlights the Importance of Myeloid Cells in Avian Flaviviral Infection.

Ducks are an economically important waterfowl but a natural reservoir for some zoonotic pathogens, such as influenza virus and flaviviruses. Our understanding of the duck immune system and its interaction with viruses remains incomplete. In this study, we constructed the transcriptomic landscape of duck circulating immune cells, the first line of defense in the arthropod-borne transmission of arboviruses, using high-throughput single-cell transcriptome sequencing, which defined 14 populations of peripheral blood leukocytes (PBLks) based on distinct molecular signatures and revealed differences in the clustering of PBLks between ducks and humans. Taking advantage of in vivo sex differences in the susceptibility of duck PBLks to avian tembusu virus (TMUV) infection, a mosquito-borne flavivirus newly emerged from ducks with a broad host range from mosquitos to mammals, a comprehensive comparison of the in vivo dynamics of duck PBLks upon TMUV infection between sexes was performed at the single-cell level. Using this in vivo model, we discovered that TMUV infection reprogrammed duck PBLks differently between sexes, driving the expansion of granulocytes and priming granulocytes and monocytes for antiviral immune activation in males but decreasing the antiviral immune activity of granulocytes and monocytes by restricting their dynamic transitions from steady states to antiviral states with a decrease in the abundance of circulating monocytes in females. This study provides insights into the initial immune responses of ducks to arthropod-borne flaviviral infection and provides a framework for studying duck antiviral immunity.

Immune response to intravenous immunoglobulin in patients with Kawasaki disease and MIS-C.

BACKGROUNDMultisystem inflammatory syndrome in children (MIS-C) is a rare but potentially severe illness that follows exposure to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Kawasaki disease (KD) shares several clinical features with MIS-C, which prompted the use of intravenous immunoglobulin (IVIG), a mainstay therapy for KD. Both diseases share a robust activation of the innate immune system, including the IL-1 signaling pathway, and IL-1 blockade has been used for the treatment of both MIS-C and KD. The mechanism of action of IVIG in these 2 diseases and the cellular source of IL-1β have not been defined.METHODSThe effects of IVIG on peripheral blood leukocyte populations from patients with MIS-C and KD were examined using flow cytometry and mass cytometry (CyTOF) and live-cell imaging.RESULTSCirculating neutrophils were highly activated in patients with KD and MIS-C and were a major source of IL-1β. Following IVIG treatment, activated IL-1β+ neutrophils were reduced in the circulation. In vitro, IVIG was a potent activator of neutrophil cell death via PI3K and NADPH oxidase, but independently of caspase activation.CONCLUSIONSActivated neutrophils expressing IL-1β can be targeted by IVIG, supporting its use in both KD and MIS-C to ameliorate inflammation.FUNDINGPatient Centered Outcomes Research Institute; NIH; American Asthma Foundation; American Heart Association; Novo Nordisk Foundation; NIGMS; American Academy of Allergy, Asthma and Immunology Foundation.

The Contribution of Serum Complement Component 3 Levels to 90-Day Mortality in Living Donor Liver Transplantation.

The contributions of the complement system have been elucidated in the process of solid organ transplantation, including kidney transplantation. However, the role of complement in liver transplantation is unknown. We sought to elucidate the time-dependent changes of peritransplantational serum complement levels and the relationships with posttransplant outcomes and other immunological biomarkers. We enrolled 82 patients who underwent living-related donor liver transplantation (LDLT). Nine patients (11%) died within 90 days after LDLT (non-survivors). The following immunomarkers were collected preoperatively and at 1, 2, and 4 week(s) after LDLT: serum C3, C4, immunoglobulin G (IgG), and peripheral blood leukocyte populations characterized by CD3, CD4, CD8, CD16, CD19, CD20, CD22, and CD56. Consequently, C3 and C4 increased time-dependently after LDLT. Preoperatively, C3 was negatively correlated with the MELD score, Child–Pugh score, CD16-positive leukocyte percentage, and the CD56-positive leukocyte percentage. Non-survivors had lower levels of C3 at 2 weeks in comparison to survivors (median [interquartile range]: 56 [49-70] mg/dL vs. 88 [71-116] mg/dL, p=0.0059). When the cutoff value of C3 at 2 weeks to distinguish non-survivors was set to 71 mg/dL, the sensitivity, specificity, and area under the ROC curve were 87.5%, 75.0%, and 0.80, respectively. A principal component analysis showed an inverse relationship between the C3 and C4 levels and the percentage of CD8-, CD16-, and CD56-positive leukocytes at 1 and 2 week(s). All non-survivors were included in the cluster that showed higher percentages of CD8-, CD16-, and CD56-positive leukocytes at 2 weeks. In conclusion, we demonstrated the relationship between complement, outcomes, and other immunomarkers in LDLT and suggested the usefulness of C3 at 2 weeks after LDLT in distinguishing the mortality.

Targeted Deletion of CXCR2 in Myeloid Cells Alters the Tumor Immune Environment to Improve Antitumor Immunity.

Recruitment of myeloid-derived suppressor cells (MDSC) into the tumor microenvironment (TME) contributes to cancer immune evasion. MDSCs express the chemokine receptor CXCR2, and inhibiting CXCR2 suppresses the recruitment of MDSCs into the tumor and the premetastatic niche. Here, we compared the growth and metastasis of melanoma and breast cancer xenografts in mice exhibiting or not exhibiting targeted deletion of Cxcr2 in myeloid cells (CXCR2myeΔ/Δ vs. CXCR2myeWT). Detailed analysis of leukocyte populations in peripheral blood and in tumors from CXCR2myeΔ/Δ mice revealed that loss of CXCR2 signaling in myeloid cells resulted in reduced intratumoral MDSCs and increased intratumoral CXCL11. The increase in intratumoral CXCL11 was derived in part from tumor-infiltrating B1b cells. The reduction in intratumoral MDSCs coupled with an increase in intratumoral B1b cells expressing CXCL11 resulted in enhanced infiltration and activation of effector CD8+ T cells in the TME of CXCR2myeΔ/Δ mice, accompanied by inhibition of tumor growth in CXCR2myeΔ/Δ mice compared with CXCR2myeWT littermates. Treatment of tumor-bearing mice with a CXCR2 antagonist (SX-682) also inhibited tumor growth, reduced intratumoral MDSCs, and increased intratumoral B1b cells expressing CXCL11, leading to an increase in activated CD8+ T cells in the tumor. Depletion of B220+ cells or depletion of CD8+ T cells reversed the tumor-inhibitory properties in CXCR2myeΔ/Δ mice. These data revealed a mechanism by which loss of CXCR2 signaling in myeloid cells modulates antitumor immunity through decreasing MDSCs and enriching CXCL11-producing B1b cells in the TME, which in turn increases CD8+ T-cell recruitment and activation in tumors.

A Pilot Study of Galunisertib plus Stereotactic Body Radiotherapy in Patients with Advanced Hepatocellular Carcinoma.

TGFβ is a pleiotropic cytokine with immunosuppressive activity. In preclinical models, blockade of TGFβ enhances the activity of radiation and invokes T-cell antitumor immunity. Here, we combined galunisertib, an oral TGFβ inhibitor, with stereotactic body radiotherapy (SBRT) in patients with advanced hepatocellular carcinoma (HCC) and assessed safety, efficacy, and immunologic correlatives. Patients (n = 15) with advanced HCC who progressed on, were intolerant of, or refused sorafenib were treated with galunisertib (150 mg orally twice a day) on days 1 to 14 of each 28-day cycle. A single dose of SBRT (18-Gy) was delivered between days 15 to 28 of cycle 1. Site of index lesions treated with SBRT included liver (9 patients), lymph node (4 patients), and lung (2 patients). Blood for high-dimensional single cell profiling was collected. The most common treatment-related adverse events were fatigue (53%), abdominal pain (46.6%), nausea (40%), and increased alkaline phosphatase (40%). There were two instances of grade 2 alkaline phosphatase increase and two instances of grade 2 bilirubin increase. One patient developed grade 3 achalasia, possibly related to treatment. Two patients achieved a partial response. Treatment with galunisertib was associated with a decrease in the frequency of activated T regulatory cells in the blood. Distinct peripheral blood leukocyte populations detected at baseline distinguished progressors from nonprogressors. Nonprogressors also had increased CD8+PD-1+TIGIT+ T cells in the blood after treatment. We found galunisertib combined with SBRT to be well tolerated and associated with antitumor activity in patients with HCC. Pre- and posttreatment immune profiling of the blood was able to distinguish patients with progression versus nonprogression.

Effect of climatic factors on urinary cortisol and peripheral blood leukocytes in lambs grazing on a semi-natural grassland in the Hokuriku District of Japan.

The effects of climatic factors on stress and immune functions of grazing lambs in summer and autumn in the Hokuriku District of Japan were evaluated by determining urinary cortisol (U-COR) levels and peripheral blood leukocyte populations and comparing those with lambs kept indoors. Two groups of five lambs, consisting of those grazed on a semi-natural grassland (GRL) and those housed indoors in a domestic animal shelter (INL), were maintained at from July to October. The temperature-humidity index at each location was indicative of heat stress during summer; however, the U-COR elevation was not observed in both groups. The elevation was observed in GRL in autumn and was higher than INL in October. Climatic conditions in autumn were characterized by high humidity and a sudden drop in temperature. U-COR was positively correlated with the relative humidity. The GRL was exposed to low-nutrient conditions for a relatively long time. The CD4+ /CD8+ T cell ratio in GRL decreased in October. Subsequently, the total leucocyte, including granulocytes, monocytes, and lymphocytes, sharply increased. The responses indicated an immune deficiency caused by immunosuppression because of a low nutrition caused by grazing and high-stress conditions in autumn.

Immunological imprint of COVID-19 on human peripheral blood leukocyte populations.

BackgroundSARS‐CoV‐2 has triggered a pandemic that is now claiming many lives. Several studies have investigated cellular immune responses in COVID‐19‐infected patients during disease but little is known regarding a possible protracted impact of COVID‐19 on the adaptive and innate immune system in COVID‐19 convalescent patients.MethodsWe used multiparametric flow cytometry to analyze whole peripheral blood samples and determined SARS‐CoV‐2‐specific antibody levels against the S‐protein, its RBD‐subunit, and viral nucleocapsid in a cohort of COVID‐19 convalescent patients who had mild disease ~10 weeks after infection (n = 109) and healthy control subjects (n = 98). Furthermore, we correlated immunological changes with clinical and demographic parameters.ResultsEven ten weeks after disease COVID‐19 convalescent patients had fewer neutrophils, while their cytotoxic CD8+ T cells were activated, reflected as higher HLA‐DR and CD38 expression. Multiparametric regression analyses showed that in COVID‐19‐infected patients both CD3+CD4+ and CD3+CD8+ effector memory cells were higher, while CD25+Foxp3+ T regulatory cells were lower. In addition, both transitional B cell and plasmablast levels were significantly elevated in COVID‐19‐infected patients. Fever (duration, level) correlated with numbers of central memory CD4+ T cells and anti‐S and anti‐RBD, but not anti‐NC antibody levels. Moreover, a “young immunological age” as determined by numbers of CD3+CD45RA+CD62L+CD31+ recent thymic emigrants was associated with a loss of sense of taste and/or smell.ConclusionAcute SARS‐CoV‐2 infection leaves protracted beneficial (ie, activation of T cells) and potentially harmful (ie, reduction of neutrophils) imprints in the cellular immune system in addition to induction of specific antibody responses.

Leukocyte populations in peripheral blood of dromedary camels with clinical endometritis

Endometritis represents the main cause of reproductive failure in dromedary camels. In dromedary camels, associations between endometritis-causing pathogen-species, disease severity, and systemic changes in the immune system have not been evaluated. In the current study, there was use of flow cytometry and immunofluorescence of membrane proteins for the evaluation of leukocyte subsets and the cellular phenotype in blood of camels with clinical endometritis and evaluations of associations with disease severity and endometritis-causing pathogens. Animals with endometritis had markedly larger numbers of total leukocytes and neutrophils. Although total lymphocyte and monocyte counts did not differ between camels with and without clinical endometritis, there were lesser numbers of total and effector CD4-positive T cells in camels with endometritis. Among monocytes, number of camel inflammatory monocytes (Mo-II) was markedly greater, whereas Mo-III numbers were less in the blood of camels with clinical endometritis. Number of inflammatory monocytes was also indicative of endometritis severity grade. Among camels with clinical endometritis, E. coli- and S. aureus-infected animals had similar endometritis grades and comparable phenotype and composition patterns of leukocytes. Neutrophils and monocytes of camels with clinical endometritis had fewer cell adhesion molecules (i.e., CD11a and CD18). Collectively, the results from the current study allowed for identification of associations between endometritis severity grade and larger numbers of inflammatory monocytes. The results also indicate there is no association between endometritis pathogen-species and changes in phenotype or composition of blood leukocytes.

Effect of Beta-Carotene Supplementation on the Peripheral Blood Leukocyte Population in Japanese Black Calves.

The purpose of this study was to determine the effect of beta-carotene supplementation to Japanese Black calves on the peripheral blood leukocyte population. Twenty-two Japanese Black calves were alternately assigned to two groups. Eleven calves received 20 mg/d of beta-carotene orally from 2 to 8 wk of age (BC group), and the other 11 calves did not receive (control group). The serum beta-carotene concentration in the BC group at 4, 8 and 12 wk of age were significantly higher than those in the control group (p<0.05). The numbers of CD4+ cells in the BC group were significantly higher than those in the control group at 4 wk of age (p<0.05). These results confirmed that beta-carotene supplementation to Japanese Black calves affected the peripheral blood leukocyte population.

Abstract P451: Aircraft Noise Exposure As A Novel Risk Factor For Clonal Hematopoiesis Of Indeterminate Potential

Background: Although the etiology of clonal hematopoiesis of indeterminate potential (CHIP) remains unclear, CHIP-defining somatic mutations within hematopoietic stem cells appear to expand peripheral blood leukocyte populations, promote inflammation, and thereby increase cardiovascular disease (CVD) risk. Moreover, high noise exposures have been linked to chromosomal aberrations in bone marrow and DNA repair in peripheral blood leukocytes. We therefore examined the potential of aircraft noise exposure as a novel risk factor for CHIP. Methods: We leveraged cross-sectional data on 10,050 postmenopausal women without prior hematologic malignancy in a Women’s Health Initiative (WHI) ancillary study of 5,309 women with stroke and/or venous thromboembolic disease and 4,741 controls. We ascertained CHIP using Trans-Omics for Precision Medicine (TOPMed) whole-genome sequencing data, the GATK Mu TECT2 somatic variant caller, a pre-specified list of leukemogenic driver mutations in 74 genes, and a threshold variant allele frequency of &gt; 0.02. In cooperation with the Federal Aviation Administration, we generated day-night-level (DNL) noise contours around 90 major U.S. airports using the Aviation Environmental Design Tool noise modelling software. The DNL imposes a penalty for nighttime noise exposure and is the primary means for assessing and regulating noise exposure in the U.S. We estimated geocoded participant address-specific, annual average DNL aircraft noise exposures in decibels (dB) from the contours on the day of blood draw and categorized individuals as exposed or non-exposed (DNL ≥ or &lt; 45dB). We estimated the noise-related risk of CHIP as an odds ratio, 95% confidence interval (OR, 95% CI) using logistic regression before and after adjustment for age, race / ethnicity, case-control status, smoking, alcohol use, body mass index, physical activity, hearing loss, education, and neighborhood socioeconomic status. Results: Among this population of postmenopausal women (Mean age: 68.7 years; White: 82.1%; African American: 12.3%), 19.4% were exposed to aircraft noise, and 8.4% had CHIP. The age-adjusted CHIP proportion was higher among whites (8.1%) than African Americans (7.3%) and other racial/ethnic groups (6.4%). CHIP was also more common among women aged ≥ 70 years (11.5%) than those aged 60-69 years (7.5%) or 50-59 years (3.8%). Compared to non-exposed women, those exposed to aircraft noise were not at increased risk of CHIP: OR unadjusted (95% CI) = 0.95 (0.80, 1.14) and OR adjusted (95% CI) = 0.97 (0.81, 1.16). Results were insensitive to dichotomization of noise exposure at 55 dB and further exclusion of women with hearing loss. Conclusion: Our study found no evidence of an association between aircraft noise and CHIP suggesting that aircraft noise may not be a factor contributing to CHIP-defining somatic mutations linked to CVD.

Exposure to the UV Filter Octyl Methoxy Cinnamate in the Postnatal Period Induces Thyroid Dysregulation and Perturbs the Immune System of Mice.

Evidence demonstrates the bidirectional communication and regulation between the neuroendocrine and immune systems. Thyroid hormones play key roles in nervous system development and can exert influence on various immune cells contributing to pathophysiological conditions. Octyl methoxycinnamate (OMC) is one of the most commonly used UV filters, and in vitro and in vivo studies have found thyroid disrupting effects. The present study assessed whether OMC administration in mice dams during the lactational period can cause thyroid disruption and generate immunologic alterations in the offspring. Indirect exposure to the OMC (1,000 mg/kg) in the lactational period affected neurodevelopment parameters, such as delayed eye-opening and weight gain in mice of both sexes, and these alterations are corroborated by the decrease in the T4 levels present in the pups' blood. No significant changes were observed in the thymus of these pups, but the number of lymphocytes increased in the spleen of the animals exposed to OMC, similar to the animals treated with propyl-thiouracil (PTU), a well-known thyroid disruptor. OMC modulated the percentage of leukocyte populations in peripheral blood, and the number of circulating polymorphonuclear cells increased two-fold. In vitro, OMC exhibited an inhibitory effect on splenocyte proliferation and IL-2 production induced by anti-CD3 antibody; however, this effect was reversed with the addition of T4 in the cell culture. In summary, the results of the present study demonstrate the influence of OMC on thyroid dysregulation and its impact on the modulation of the immune system in mice pups.

Elevated circulating CD14++CD16+ intermediate monocytes are independently associated with extracardiac complications after cardiac surgery

Elective cardiac surgery has low procedural complications. However, about 40% of patients develop extracardiac complications including delirium and acute kidney injury. We hypothesized that inflammatory processes and immune cell activation might be associated with these complications. We therefore prospectively included 104 patients undergoing cardiac surgery in our study. We assessed peripheral blood leukocyte populations by flow cytometry and circulating cytokines before operation, after surgery and at days one and four post-operatively. Patients undergoing cardiac surgery showed significantly elevated leukocytes and neutrophils after surgery. On the contrary, monocytes decreased after surgery and significantly increased at days 1 and 4, particularly classical (Mon1,CD14++CD16−) and intermediate (Mon2,CD14++CD16+) monocytes. While peripheral leukocyte subsets were unaltered in patients with infectious (n = 15) or cardiac complications (n = 31), post-operative leukocytes (p = 0.0016), neutrophils (p = 0.0061) and Mon2 (p = 0.0007) were clearly raised in patients developing extracardiac complications (n = 35). Using multiple logistic regression analyses, patient’s age, ICU days, number of blood transfusions and elevated post-surgery Mon2 independently predicted extracardiac complications. Our findings demonstrate that elevated Mon2 after cardiac surgery are associated with an increased risk for extracardiac complications. These findings might improve the risk estimation after cardiac operations and the role of Mon2 for inflammation in cardiac surgery.

Regulatory Effects of Stachyose on Colonic and Hepatic Inflammation, Gut Microbiota Dysbiosis, and Peripheral CD4+ T Cell Distribution Abnormality in High-Fat Diet-Fed Mice.

A long-term high-fat diet (HFD) can cause a range of health problems. Gut microbiota plays a decisive role in the development of HFD-associated inflammation, involved in function of T cells. This study was designed to probe the regulative effects of dietary stachyose, a functional oligosaccharide, on HFD-induced weight gain, inflammation, gut microbiota dysbiosis, and T cell abnormality in C57Bl/6 mice. Mice were divided into three groups which received normal chow, HFD and HFD plus stachyose (400 mg/kg), respectively. Results showed that administration of stachyose diminished the HFD-induced upregulation of serum TNF-α level and elevation of peripheral blood leukocyte populations to alleviate the HFD-caused colonic and hepatic inflammation in mice. Analysis of gut microbiota revealed that stachyose improved the intestinal homeostasis of HFD-fed mice by improving the bacterial diversity with the increases in the relative abundances of the Prevotellaceae_NK3B31_group, Parasutterella, Christensenellaceae_R-7_group, and Anaerovorax, as well as the fecal level of butanoic acid, while decreasing the ratio of Firmicutes-to-Bacteroidetes and the abundances of the Lachnospiraceae_NK4A136_group, Desulfovibrio, Anaerotruncus, Mucispirillum, Roseburia, and Odoribacter. Flow cytometric analysis showed that stachyose antagonized the HFD-induced decrease of peripheral CD4+ T cell population in mice. Conclusively, these findings suggest that long-term consumption of stachyose can ameliorate the HFD-associated colonic and hepatic inflammation and its complications by modulating gut microbiota.

Selective Cytotoxicity of Staphylococcal α-Hemolysin (α-Toxin) against Human Leukocyte Populations.

Staphylococcus aureus produces a variety of exoproteins that interfere with host immune systems. We attempted to purify cytotoxins against human leukocytic cells from the culture supernatant of S. aureus by a combination of ammonium sulfate precipitation, ion-exchange chromatography on a CM-cellulose column and HPLC on a Mono S 5/50 column. A major protein possessing cytotoxicity to HL60 human promyelocytic leukemia cells was purified, and the protein was identified as α-hemolysin (Hla, α-toxin) based on its molecular weight (34 kDa) and N-terminal amino acid sequence. Flow cytometric analysis suggested differential cytotoxicity of Hla against different human peripheral blood leukocyte populations. After cell fractionation with density-gradient centrifugation, we found that peripheral blood mononuclear cells (PBMCs) were more susceptible to Hla than polymorphonuclear leukocytes. Moreover, cell surface marker analysis suggested that Hla exhibited slightly higher cytotoxicity against CD14-positive PBMCs (mainly monocytes) than CD3- or CD19-positive cells (T or B lymphocytes). From these results, we conclude that human leukocytes have different susceptibility to Hla depending on their cell lineages, and thereby the toxin may modulate the host immune response.