'FcαRI (CD89) is upregulated on subsets of mucosal and circulating NK cells and regulates IgA-class specific signaling and functions

Immunoglobulin A (IgA) is the predominant mucosal antibody class with both anti- and pro-inflammatory roles [1-3]. However, the specific role of the IgA receptor CD89, expressed by a subset of natural killer (NK) cells, is poorly explored. We found that CD89 protein expression on circulating NK cells is infrequent in humans and rhesus macaques, but transcriptomic analysis showed ubiquitous CD89 expression, suggesting an inducible phenotype. Interestingly, CD89+ NK cells were more frequent in cord blood and mucosae, indicating a putative IgA-mediated NK cell function in the mucosae and infant immune system. CD89+ NK cells signaled through upregulated CD3ζ, SYK, ZAP70, and SLAMF1, but also showed high expression of inhibitory receptors such as KLRG1 and reduced activating NKp46 and NKp30. CD89-based activation or ADCC with monomeric IgA1 reduced NK cell functions, while ADCC with combinations of IgG and IgA2 was enhanced compared to IgG alone. These data suggest that functional CD89+ NK cells survey mucosal sites, but CD89 likely serves as regulatory receptor which can be further modulated depending on IgA and IgG subclass. Although the full functional niche of CD89+ NK cells remains unexplored, these intriguing data suggest the CD89 axis could represent a novel immunotherapeutic target in the mucosae or early life.

Multiplex interrogation of the NK cell signalome reveals global downregulation of CD16 signaling during lentivirus infection through an IL-18/ADAM17-dependent mechanism

Despite their importance, natural killer (NK) cell responses are frequently dysfunctional during human immunodeficiency virus-1 (HIV-1) and simian immunodeficiency virus (SIV) infections, even irrespective of antiretroviral therapies, with poorly understood underlying mechanisms. NK cell surface receptor modulation in lentivirus infection has been extensively studied, but a deeper interrogation of complex cell signaling is mostly absent, largely due to the absence of any comprehensive NK cell signaling assay. To fill this knowledge gap, we developed a novel multiplex signaling analysis to broadly assess NK cell signaling. Using this assay, we elucidated that NK cells exhibit global signaling reduction from CD16 both in people living with HIV-1 (PLWH) and SIV-infected rhesus macaques. Intriguingly, antiretroviral treatment did not fully restore diminished CD16 signaling in NK cells from PLWH. As a putative mechanism, we demonstrated that NK cells increased surface ADAM17 expression via elevated plasma IL-18 levels during HIV-1 infection, which in turn reduced surface CD16 downregulation. We also illustrated that CD16 expression and signaling can be restored by ADAM17 perturbation. In summary, our multiplex NK cell signaling analysis delineated unique NK cell signaling perturbations specific to lentiviral infections, resulting in their dysfunction. Our analysis also provides mechanisms that will inform the restoration of dysregulated NK cell functions, offering potential insights for the development of new NK cell-based immunotherapeutics for HIV-1 disease.

Multiplex Analysis of Cytokines and Chemokines in Persons Aging With or Without HIV

People with HIV (PWH) on combination antiretroviral therapy (cART) are living longer lives due to modern cART advances and increased routine medical care. The full landscape of aging with HIV is unclear; given that HIV emerged relatively recently in human history and initially had a high mortality rate, there has not been a substantially aged population to evaluate. In this study, we set out to perform high-throughput plasma analyte profiling by multiplex analysis, focusing on various T helper (Th)-related cytokines, chemokines, and proinflammatory and anti-inflammatory cytokines. The primary goals being to provide reference ranges of these analytes for aging PWH cohorts, as well as testing the utility of high-throughput multiplex plasma assays. The cohort used in this study comprised age-matched healthy donors (32.6-73.5 years of age), PWH on cART (26.7-60.2 years of age), and viremic PWH (27.5-59.4 years of age). The patients in each group were then stratified across the age span to examine age-related impacts of these plasma biomarkers. Our results largely indicate feasibility of plasma analyte monitoring by multiplex and demonstrate a high degree of person-to-person variability regardless of age and HIV status. Nonetheless, we find multiple associations with age, duration of known infection, and viral load, all of which appear to be driven by either prolonged HIV disease progression or long-term use of cART.

Multiplex analysis of cytokines and chemokines in persons aging with or without HIV

People with HIV (PWH) on combined antiretroviral therapy (cART) are living longer lives due to modern cART advances and increased routine medical care. The full landscape of aging with HIV is unclear; given that HIV emerged relatively recently in human history and initially had a high mortality rate, there has not been a substantially aged population to evaluate. In the present study, we set out to perform high throughput plasma analyte profiling by multiplex analysis, focusing on various T helper (Th)-related cytokines, chemokines, and pro- and anti-inflammatory cytokines. The primary goals being to provide reference ranges of these analytes for aging PWH cohorts, as well as testing the utility of high throughput multiplex plasma assays. The cohort used in this study was comprised of age-matched healthy donors (aged 32.6-73.5), PWH on cART (aged 26.7-60.2), and viremic PWH (aged 27.5-59.4). The patients in each group were then stratified across the age span to examine age-related impacts of these plasma biomarkers. Our results largely indicate feasibility of plasma analyte monitoring by multiplex and demonstrate a high degree of person-to-person variability regardless of age and HIV status. Nonetheless, we find multiple associations with age, duration of known infection, and viral load, all of which appear to be driven by either prolonged HIV disease progression or long-term use of cART.

NK cell education: Physiological and pathological influences

Natural killer (NK) cells represent a critical defense against viral infections and cancers. NK cells require integration of activating and inhibitory NK cell receptors to detect target cells and the balance of these NK cell inputs defines the global NK cell response. The sensitivity of the response is largely defined by interactions between self-major histocompatibility complex class I (MHC-I) molecules and specific inhibitory NK cell receptors, so-called NK cell education. Thus, NK cell education is a crucial process to generate tuned effector NK cell responses in different diseases. In this review, we discuss the relationship between NK cell education and physiologic factors (type of self-MHC-I, self-MHC-I allelic variants, variant of the self-MHC-I-binding peptides, cytokine effects and inhibitory KIR expression) underlying NK cell education profiles (effector function or metabolism). Additionally, we describe the broad-spectrum of effector educated NK cell functions on different pathologies (such as HIV-1, CMV and tumors, among others).

Mucosal-homing natural killer cells are associated with aging in persons living with HIV

Natural killer (NK) cells are critical modulators of HIV transmission and disease. Recent evidence suggests a loss of NK cell cytotoxicity during aging, yet analysis of NK cell biology and aging in people with HIV (PWH) is lacking. Herein, we perform comprehensive analyses of people aging with and without HIV to determine age-related NK phenotypic changes. Utilizing high-dimensional flow cytometry, we analyze 30 immune-related proteins on peripheral NK cells from healthy donors, PWH with viral suppression, and viremic PWH. NK cell phenotypes are dynamic across aging but change significantly in HIV and on antiretroviral drug therapy (ART). NK cells in healthy aging show increasing ⍺4β7 and decreasing CCR7 expression and a reverse phenomenon in PWH. These HIV-associated trafficking patterns could be due to NK cell recruitment to HIV reservoir formation in lymphoid tissue or failed mucosal signaling in the HIV-infected gut but appear to be tight delineators of age-related NK cell changes.

Systemic and mucosal mobilization of granulocyte subsets during lentiviral infection

Granulocytes mediate broad immunoprotection through phagocytosis, extracellular traps, release of cytotoxic granules, antibody effector functions and recruitment of other immune cells against pathogens. However, descriptions of granulocytes in HIV infection and mucosal tissues are limited. Our goal was to characterize granulocyte subsets in systemic, mucosal and lymphoid tissues during lentiviral infection using the rhesus macaque (RM) model. Mononuclear cells from jejunum, colon, cervix, vagina, lymph nodes, spleen, liver and whole blood from experimentally naïve and chronically SHIVsf162p3-infected RM were analysed by microscopy and polychromatic flow cytometry. Granulocytes were identified using phenotypes designed specifically for RM: eosinophils-CD45+  CD66+  CD49d+ ; neutrophils-CD45+  CD66+  CD14+ ; and basophils-CD45+  CD123+  FcRε+ . Nuclear visualization with DAPI staining and surface marker images by ImageStream (cytometry/microscopy) further confirmed granulocytic phenotypes. Flow cytometric data showed that all RM granulocytes expressed CD32 (FcRγII) but did not express CD16 (FcRγIII). Additionally, constitutive expression of CD64 (FcRγI) on neutrophils and FcRε on basophils indicates the differential expression of Fc receptors on granulocyte subsets. Granulocytic subsets in naïve whole blood ranged from 25·4% to 81·5% neutrophils, 0·59% to 13·3% eosinophils and 0·059% to 1·8% basophils. Interestingly, elevated frequencies of circulating neutrophils, colorectal neutrophils and colorectal eosinophils were all observed in chronic lentiviral disease. Conversely, circulating basophils, jejunal eosinophils, vaginal neutrophils and vaginal eosinophils of SHIVsf162p3-infected RM declined in frequency. Overall, our data suggest modulation of granulocytes in chronic lentiviral infection, most notably in the gastrointestinal mucosae where a significant inflammation and disruption occurs in lentivirus-induced disease. Furthermore, granulocytes may migrate to inflamed tissues during infection and could serve as targets of immunotherapeutic intervention.

HISTOLOGICAL CHANGES FOLLOWING OVARIECTOMY IN MICE : I. dba HIGH TUMOR STRAIN

1. In dba mice ovariectomized at birth the vagina, uterus, and mammary glands showed a gradual recovery from the castrate state, and finally reached the stage which they presumably can attain only under the influence of estrogenic hormones. Tumors of the mammary glands developed in 37 animals, of 75 examined, between the ages of 14 and 28 months (3 adenomas and 34 carcinomas). 2. As ovarian regeneration had not taken place the probability that estrogen originated in some other organ in the absence of the ovaries is suggested. 3. The consistent nodular hyperplasia of the suprarenal cortex and close morphological similarity of cells of these nodules to lutein-like cells of the ovaries points to the abnormal suprarenals as possible sources of the estrogenic hormones.

Effects of neuropeptides, ruthenium red and neuraminidase on chemoreflexes mediated by afferents in the dog epicardium

1. Experiments were performed on anaesthetized, open-chest dogs to determine reflex effects on blood pressure and heart rate produced by stimulation of neural afferents of the left ventricular epicardium by local application of capsaicin, bradykinin, nicotine and the neuropeptides substance P (SP), neurokinin A (NKA), neurokinin B (NKB) and calcitonin gene-related peptide (CGRP). 2. Studies also included assessing whether reflexogenic actions of capsaicin, bradykinin and nicotine are influenced by epicardial treatment with either neuropeptides, Ruthenium Red or neuraminidase. 3. Epicardial application of either capsaicin (0.1-10 micrograms) or bradykinin (0.1-1 micrograms), consistently resulted in dose-related increases in blood pressure and heart rate, whereas reflex bradycardia and hypotensive effects were initiated by the application of nicotine (30-50 micrograms). 4. SP, NKA, NKB and CGRP caused marked hypotensive effects and tachycardia when injected intravenously (1 microgram), but failed to produce any cardiovascular response when applied to the epicardium of the left ventricle (0.1-1 microgram). Treatment of the heart surface with these neuropeptides (0.05-0.5 micrograms min-1) was also without any effect on the magnitude of reflex responses evoked by epicardial application of either capsaicin, bradykinin or nicotine. 5. Superfusion of the ventricular epicardium with Ruthenium Red (10-30 microM), a cationic dye known to have sialic acid as a molecular target, antagonized the reflexogenic effects of capsaicin but not those of bradykinin or nicotine. The reflex effects of capsaicin, but not those of bradykinin, were also sensitive to inhibition by epicardial treatment with neuraminidase, an enzyme which cleaves sialic acid residues from glycosides and sialoglycoproteins. 6. We conclude that neuropeptides which may be released from the peripheral endings of some cardiac sensory neurons neither directly activate nor sensitize spinal sympathetic and vagal afferents in the dog heart to the reflexogenic action of bradykinin, nicotine or capsaicin. 7. We further suggest that activation of the cardiac sympathetic chemoreflex by capsaicin involves its interaction with calcium-binding sialic acid moieties present on the surface of axons and/or terminals of chemosensitive sympathetic afferents distributed in the dog ventricular epicardium.

Mechanical, energetic, and biochemical changes in long-term pressure overload of rabbit heart

The mechanical and energetic consequences of long-term pressure-overload (POL) hypertrophy have been investigated in rabbits and compared with sham-operated controls (SOC). Hypertrophy was induced by banding the pulmonary artery of young rabbits and examining the mechanical, biochemical, and energetic properties of the compensated heart 10-16 wk later. Experiments were undertaken on papillary muscles from the hypertrophic hearts. At 27 degrees C and a stimulus frequency of 1 Hz there was a modest depression of peak stress development but no significant changes in isometric rise times and one-half widths or in isotonic maximum velocity of shortening and power output. The inverse relationship between peak stress and cross-sectional area (CSA) was practically identical in the POL and SOC groups. Both polarographic and myothermic investigations were made on papillary muscles. Hypertrophy nearly halved basal metabolism, and in isometric contractions there was increased isometric economy due to a combination of a lower stress cost and a reduced activation heat. Hypertrophy did significantly depress the extent of shortening leading to a reduced work output per beat. In isotonic contractions the reduced work output was offset by a reduced energy output such that there was no significant change in suprabasal mechanical efficiency. Biochemical studies showed that the transition of myosin isoenzymes to the V3 form was essentially complete in the POL group, but that the SOC group was also predominantly V3 when the animals were killed. There was a significant 30% decline in the Ca2(+)-stimulated adenosinetriphosphatase activity of the sarcoplasmic reticulum. It is concluded that in long-term compensated hypertrophy of rabbit hearts there are only a few mechanical and energetic differences between control and hypertrophic muscles. The changes that can be detected appear to predominantly reflect disturbances in cellular Ca2+ regulation.

A role for cyclic GMP in the initiation of cardiac pressor reflexes by bradykinin and capsaicin

Reflexogenic effects of bradykinin on the cardiac sympathetic afferents supplying the dog epicardium were inhibited by treatment of the heart surface with either methylene blue or the compound LY-83583 (6-anilino-5,8-quinolinedione), which are known to lower cellular levels of cyclic GMP. Stimulation of cyclic GMP production by epicardial treatment with the NO-containing synonimine compound, SIN-1, potentiated bradykinin-induced reflex effects. In contrast, the sympathetic cardiac pressor response induced by capsaicin was not influenced by epicardial treatment with either methylene blue, LY-83583 or SIN-1. These findings indicate the importance of cyclic GMP for the reflexogenic activity of bradykinin, but not that of capsaicin on the sympathetic afferents supplying the dog heart.

Cardiac nociceptive reflexes: role of kinins, prostanoids and capsaicin-sensitive afferents

Spinal sympathetic afferent fibres with endings in the heart are essential for signalling cardiac pain. In anesthetized, open-chest dogs, stimulation of these cardiac afferents with the algesic agents, bradykinin or capsaicin, results in reflex increases in arterial pressure and cardiac rate. The reflex responses induced by bradykinin are enhanced by concomitant application of prostaglandins of the E type or prostacyclin, and reduced by indomethacin. In contrast, the reflex effects of capsaicin are not influenced by either indomethacin or prostaglandin E1 treatment. Evidence is presented that reflexogenic effects of bradykinin involve its interaction with specific B2-receptors for kinins and that proteolysis of endogenous kininogen precursor to kinins by epicardially applied tissue kallikrein can initiate reflex cardiovascular effects.

Lymphocyte ectoenzyme activity compared in healthy persons and patients seropositive to or at high risk of HIV infection

We measured two ectoenzymes, ecto-5'-nucleotidase (NT) and dipeptidyl peptidase IV (DP) in the peripheral blood lymphocytes of various groups of HIV-infected patients because of the previous implied relationship of these enzymes to immune function. NT expressed as mean nmol/h per mg protein (+/- s.d.) was significantly depressed in the HIV-seropositive asymptomatic (42 +/- 32; P less than 0.01) and AIDS groups (14 +/- 7; P less than 0.002) when compared with a healthy HIV-seronegative male population (83 +/- 27). The NT activities in asymptomatic HIV-seropositive and HIV-seronegative high risk groups (53 +/- 30) were not significantly different from one another but both groups had significantly higher enzyme activities than the AIDS group (P = 0.01 and less than 0.002, respectively). The seronegative high risk and normal healthy group had similar NT activities. DP activities expressed as mean nmol/h per mg protein (+/- s.d.) in both seropositive asymptomatic (0.188 +/- 0.038) and high risk seronegative (0.180 +/- 0.05) groups had higher enzyme activities than the healthy seronegative (0.117 +/- 0.015; P = 0.02 and 0.05, respectively) and AIDS group (0.096 +/- 0.036; P = 0.002 and 0.02, respectively). The healthy seronegative group had DP activities not significantly different to the AIDS groups. Similarly the high risk seronegative and healthy seropositive group had similar DP activities. These results taken together indicate that measurement of both DP and NT should be evaluated prospectively as a monitor of the clinical progression of HIV infection.

Participation of the kallikrein-kinin-receptor system in reflexes arising from neural afferents in the dog epicardium

1. Reflexogenic effects of bradykinin, lysyl-bradykinin and endogenously formed kinins on neural afferents of the left ventricular epicardium were studied in anaesthetized, open-chest dogs. 2. Epicardial application of either bradykinin (0.01-10 micrograms), lysyl-bradykinin (0.01-10 micrograms) or tissue kallikrein (0.003-1 U) consistently resulted in dose-related increases in blood pressure and heart rate. The pressor and heart rate responses to epicardial kallikrein were slower in onset and longer lasting than those evoked by bradykinin or lysyl-bradykinin. The effects of kallikrein, but not those of exogenous kinins, were subject to tachyphylaxis. The application of higher doses of kallikrein (0.1 or 1 U) also resulted in long-lasting desensitization of the epicardium to the effects of bradykinin. 3. Treatment of the epicardium with a proteinase inhibitor, aprotinin, prevented the reflexogenic effects of kallikrein but not those of bradykinin or lysyl-bradykinin. Treatment with aprotinin also counteracted post-kallikrein desensitization of sensory receptors of the ventricular epicardium to the reflexogenic effect of bradykinin. 4. Superfusion of the epicardium with a selective B2 receptor antagonist, D-Arg[Hyp3,Thi5,8,D-Phe7]-bradykinin, was equally effective in antagonizing the reflexogenic effects of kallikrein, bradykinin and lysyl-bradykinin. 5. We conclude that the response to epicardial application of kallikrein indicates an ample presence of endogenous substrate for local formation of bradykinin and/or related kinins. These then initiate reflex activation of the cardiovascular system by interacting with specific B2 receptors associated with sympathetic afferent neurones in the dog epicardium. We suggest that the kallikrein-kinin-receptor system has a role in the reflex function of the cardiac sympathetic afferents in both physiological and pathological conditions.

Specific receptors for bradykinin-induced cardiac sympathetic chemoreflex in the dog

Bradykinin (BK, 0.03-1 microgram), capsaicin (1 microgram) or potassium chloride (KCl, 13 mumol) applied to the epicardium of the left ventricle of anaesthetized, open-chest dogs, caused reflex tachycardia and pressor effects, whereas des-Arg9-BK (1-100 micrograms), a selective bradykinin B1-receptor agonist, failed to produce any cardiovascular response. Superfusion of the epicardium with a selective B1-receptor antagonist, des-Arg9-[Leu8]BK (50-100 micrograms/min) had no effect on reflex responses to epicardial BK (0.03-0.1 microgram). However, the selective B2-receptor antagonist, D-Arg-[Hyp3,Thi5,8,D-Phe7]BK (10-25 micrograms/min) abolished the reflex effects of 0.03 and 0.1 microgram BK and reduced by 50 to 70% the responses to 1 microgram BK. Another B2-receptor antagonist [Thi6,9,D-Phe8]kallidin (10-50 micrograms/min) also reduced (30-70%) responses to 1 microgram BK. The antagonism was reversible and specific for BK since reflex responses to epicardial application of either capsaicin or KCl were not affected. The results indicate that BK interacts with B2-receptors, probably located on terminals and/or axons of sympathetic afferents supplying the dog heart, to activate a cardiac sympathetic chemoreflex.

Protein binding studies of technetium-99m-labeled phosphine and isocyanide cationic complexes

Most 99mTc/phosphine/isocyanide complexes synthesized to date show preferential uptake by the myocardium of many animal species but not in man. A new complex has been synthesized, [99mTc(DEPE)2(CNR)2], +(DEPIC), where R = t - butyl isocyanide, which in three animal species images the myocardium very well, but in humans it remains primarily in the blood pool. One reason for the difference in the behavior of these complexes in different species could be the characteristics of their binding to plasma proteins. The protein binding characteristics of DEPIC and two other well-known complexes have therefore been studied. Whereas the other complexes bind nonspecifically to many proteins both in animal and human plasma, DEPIC binds almost exclusively to prealbumin in humans but nonspecifically to other proteins in the rabbit. The binding sites in human plasma appear to be those normally occupied by thyroxine on the prealbumin tetramer and these can be blocked by sodium salicylate.

Cardiac energetics in daunorubicin-induced cardiomyopathy

Daunorubicin (DNR) was administered to one of each pair of litter mate rabbits at a weekly dosage rate of 40 mg/m2. Treated animals were killed when their pre-ejection period: left ventricular ejection time ratio (PEP:LVET) reached or exceeded 0.4. Mechanical, myothermic and polarographic measurements were made upon papillary muscles obtained from the right ventricle of DNR treated rabbits and their litter mate controls. DNR treatment significantly increased the PEP:LVET ratio (41%) and increased the left ventricular: body weight ratio (24%). Basal metabolism, measured 2 h after cardiectomy, was significantly reduced whether measured myothermically or polarographically: both measurements were highly correlated but the O2 consumption values were higher. Peak stress development was 31% lower in the DNR treated rabbits but this reduction was largely accounted for by a larger cross-sectional area (CSA) of the papillary muscles in this group. There was no change in the slope of the active heat: stress relationships but the stress-independent (activation) heat intercept was depressed. In isotonic studies DNR treatment caused a 57% reduction in work output per beat (relative to controls) and a 39% decline in active energy output. Because of the approximately parallel shift in work and total energy output mechanical efficiency was not significantly changed. It is suggested that part of the basal energy production fall produced by DNR relates to protein synthesis inhibition but that most of the other mechanical and energetic effects are probably explicable in terms of the intrinsic hypertrophic response of the 'failing' heart.