NK cells reduce anergic T cell development in early-stage tumors by promoting myeloid cell maturation

Introduction

Studies of NK cells in tumors have primarily focused on their direct actions towards tumor cells. We evaluated the impact of NK cells on expression of homing receptor ligands on tumor vasculature, intratumoral T cell number and function, and T cell activation in tumor draining lymph node.

Methods

Using an implantable mouse model of melanoma, T cell responses and homing receptor ligand expression on the vasculature were evaluated with and without NK cells present during the early stages of the tumor response by flow cytometry.

Results

NK cells in early-stage tumors are one source of IFNγ that augments homing receptor ligand expression. More significantly, NK cell depletion resulted in increased numbers of intratumoral T cells with an anergic phenotype. Anergic T cell development in tumor draining lymph node was associated with increased T-cell receptor signaling but decreased proliferation and effector cell activity, and an incomplete maturation phenotype of antigen presenting cells. These effects of NK depletion were similar to those of blocking CD40L stimulation.

Discussion

We conclude that an important function of NK cells is to drive proper APC maturation via CD40L during responses to early-stage tumors, reducing development of anergic T cells. The reduced development of anergic T cells resulting in improved tumor control and T cell responses when NK cells were present.

Tumor necrosis factor receptor regulation of peripheral node addressin biosynthetic components in tumor endothelial cells

Tumor-associated tertiary lymphoid structures are ectopic lymphoid aggregates that have considerable morphological, cellular, and molecular similarity to secondary lymphoid organs, particularly lymph nodes. Tumor vessels expressing peripheral node addressin (PNAd) are hallmark features of these structures. Previous work from our laboratory demonstrated that PNAd is displayed on intratumoral vasculature of murine tumors, and its expression is controlled by the engagement of lymphotoxin-α₃, secreted by effector CD8 T cells, with tumor necrosis factor receptors (TNFR) on tumor endothelial cells (TEC). The goals of the present work were: 1) to identify differences in expression of genes encoding the scaffolding proteins and glycosyl transferases associated with PNAd biosynthesis in TEC and lymph node blood endothelial cells (LN BEC); and 2) to determine which of these PNAd associated components are regulated by TNFR signaling. We found that the same genes encoding scaffolding proteins and glycosyl transferases were upregulated in PNAd⁺ LN BEC and PNAd⁺ TEC relative to their PNAd^neg counterparts. The lower level of PNAd expression on TEC vs LN BEC was associated with relatively lower expression of these genes, particularly the carbohydrate sulfotransferase Chst4. Loss of PNAd on TEC in the absence of TNFR signaling was associated with lack of upregulation of these same genes. A small subset of PNAd⁺ TEC remaining in the absence of TNFR signaling showed normal upregulation of a subset of these genes, but reduced upregulation of genes encoding the scaffolding proteins podocalyxin and nepmucin, and carbohydrate sulfotransferase Chst2. Lastly, we found that checkpoint immunotherapy augmented both the fraction of TEC expressing PNAd and their surface level of this ligand. This work points to strong similarities in the regulation of PNAd expression on TEC by TNFR signaling and on LN BEC by lymphotoxin-β receptor signaling, and provides a platform for the development of novel strategies that manipulate PNAd expression on tumor vasculature as an element of cancer immunotherapy.

Immune mechanisms orchestrate tertiary lymphoid structures in tumors via cancer-associated fibroblasts

Tumor-associated tertiary lymphoid structures (TA-TLS) are associated with enhanced patient survival and responsiveness to cancer therapies, but the mechanisms underlying their development are unknown. We show here that TA-TLS development in murine melanoma is orchestrated by cancer-associated fibroblasts (CAF) with characteristics of lymphoid tissue organizer cells that are induced by tumor necrosis factor receptor signaling. CAF organization into reticular networks is mediated by CD8 T cells, while CAF accumulation and TA-TLS expansion depend on CXCL13-mediated recruitment of B cells expressing lymphotoxin-α1β2. Some of these elements are also overrepresented in human TA-TLS. Additionally, we demonstrate that immunotherapy induces more and larger TA-TLS that are more often organized with discrete T and B cell zones, and that TA-TLS presence, number, and size are correlated with reduced tumor size and overall response to checkpoint immunotherapy. This work provides a platform for manipulating TA-TLS development as a cancer immunotherapy strategy.

Differential Expression of CD49a and CD49b Determines Localization and Function of Tumor-Infiltrating CD8+ T Cells

CD8⁺ T-cell infiltration and effector activity in tumors are correlated with better overall survival of patients, suggesting that the ability of T cells to enter and remain in contact with tumor cells supports tumor control. CD8⁺ T cells express the collagen-binding integrins CD49a and CD49b, but little is known about their function or how their expression is regulated in the tumor microenvironment (TME). Here, we found that tumor-infiltrating CD8⁺ T cells initially expressed CD49b, gained CD49a, and then lost CD49b over the course of tumor outgrowth. This differentiation sequence was driven by antigen-independent elements in the TME, although T-cell receptor (TCR) stimulation further increased CD49a expression. Expression of exhaustion markers and CD49a associated temporally but not mechanistically. Intratumoral CD49a-expressing CD8⁺ T cells failed to upregulate TCR-dependent Nur77 expression, whereas CD69 was constitutively expressed, consistent with both a lack of productive antigen engagement and a tissue-resident memory-like phenotype. Imaging T cells in live tumor slices revealed that CD49a increased their motility, especially of those in close proximity to tumor cells, suggesting that it may interfere with T-cell recognition of tumor cells by distracting them from productive engagement, although we were not able to augment productive engagement by short-term CD49a blockade. CD49b also promoted relocalization of T cells at a greater distance from tumor cells. Thus, our results demonstrate that expression of these integrins affects T-cell trafficking and localization in tumors via distinct mechanisms, and suggests a new way in which the TME, and likely collagen, could promote tumor-infiltrating CD8⁺ T-cell dysfunction.

Insights into Tumor-Associated Tertiary Lymphoid Structures: Novel Targets for Antitumor Immunity and Cancer Immunotherapy

Tertiary lymphoid structures (TLS) are ectopic lymphoid aggregates that phenotypically resemble conventional secondary lymphoid organs and are commonly found at sites of chronic inflammation. They are also found in a wide variety of primary and metastatic human tumors. The presence of tumor-associated TLS (TA-TLS) is associated with prolonged patient survival, higher rates of disease-free survival, and a favorable response to current cancer therapies. However, the immune responses that occur in these structures, and how they contribute to improved clinical outcomes, remain incompletely understood. In addition, it is unknown how heterogeneity in TA-TLS cellular composition, structural organization, and anatomic location influences their functionality and prognostic significance. Understanding more about TA-TLS development, formation, and function may offer new therapeutic options to modulate antitumor immunity.

Comparative Transcriptomic Analysis Identifies a Range of Immunologically Related Functional Elaborations of Lymph Node Associated Lymphatic and Blood Endothelial Cells

Lymphatic and blood vessels are formed by specialized lymphatic endothelial cells (LEC) and blood endothelial cells (BEC), respectively. These endothelial populations not only form peripheral tissue vessels, but also critical supporting structures in secondary lymphoid organs, particularly the lymph node (LN). Lymph node LEC (LN-LEC) also have been shown to have important immunological functions that are not observed in LEC from tissue lymphatics. LN-LEC can maintain peripheral tolerance through direct presentation of self-antigen via MHC-I, leading to CD8 T cell deletion; and through transfer of self-antigen to dendritic cells for presentation via MHC-II, resulting in CD4 T cell anergy. LN-LEC also can capture and archive foreign antigens, transferring them to dendritic cells for maintenance of memory CD8 T cells. The molecular basis for these functional elaborations in LN-LEC remain largely unexplored, and it is also unclear whether blood endothelial cells in LN (LN-BEC) might express similar enhanced immunologic functionality. Here, we used RNA-Seq to compare the transcriptomic profiles of freshly isolated murine LEC and BEC from LN with one another and with freshly isolated LEC from the periphery (diaphragm). We show that LN-LEC, LN-BEC, and diaphragm LEC (D-LEC) are transcriptionally distinct from one another, demonstrating both lineage and tissue-specific functional specializations. Surprisingly, tissue microenvironment differences in gene expression profiles were more numerous than those determined by endothelial cell lineage specification. In this regard, both LN-localized endothelial cell populations show a variety of functional elaborations that suggest how they may function as antigen presenting cells, and also point to as yet unexplored roles in both positive and negative regulation of innate and adaptive immune responses. The present work has defined in depth gene expression differences that point to functional specializations of endothelial cell populations in different anatomical locations, but especially the LN. Beyond the analyses provided here, these data are a resource for future work to uncover mechanisms of endothelial cell functionality.

Cellular and molecular mechanisms regulating the development of tertiary lymphoid structures in tumor

Tertiary lymphoid structures (TLS) have been described in association with several tumor types, and they are usually associated with enhanced patient survival. However, mechanisms regulating their formation remain unknown. We found that intra- and peri-tumoral TLS develop in intraperitoneal (IP) but not subcutaneously (SC) implanted tumors. These TLS are characterized by a robust accumulation of B cells, and an associated reticular network of podoplanin+ fibroblasts expressing high levels of CXCL12, CXCL13, and the B-cell survival factors BAFF and APRIL. These results suggest that IP tumor-associated fibroblasts are polarized into organizer cells that orchestrate TLS formation. We’ve previously demonstrated that CD8 T effectors induce the development of lymph node-like vasculature in IP tumors. To determine whether these cells also regulate TLS development, we evaluated IP tumors grown in Rag1−/− mice and Rag1−/− mice repleted with bulk CD8 T cells. CD8 T cells upregulated the number of podoplanin+ fibroblasts and CXCL12 expression. However, CXCL13, BAFF and APRIL expression was not dependent on CD8 T cells. Thus, the representation of podoplanin+ fibroblasts and their expression of CXCL12 is regulated by adaptive immunity, while their expression of CXCL13, BAFF and APRIL is mediated by an innate element within the IP tumor microenvironment. We also found that increasing the load of the model tumor antigen ovalbumin led to an increased formation of peri-tumoral TLS with a classical organization, on top of the non-classical intratumoral structures evident at a low antigen load. These results identify novel mechanisms regulating different elements involved in organizing tumor-associated TLS.

Immune Cell Infiltration and Tertiary Lymphoid Structures as Determinants of Antitumor Immunity

Limited representation of intratumoral immune cells is a major barrier to tumor control. However, simply enhancing immune responses in tumor-draining lymph nodes or through adoptive transfer may not overcome the limited ability of tumor vasculature to support effector infiltration. An alternative is to promote a sustained immune response intratumorally. This idea has gained traction with the observation that many tumors are associated with tertiary lymphoid structures (TLS), which organizationally resemble lymph nodes. These peri- and intratumoral structures are usually, but not always, associated with positive prognoses in patients. Preclinical and clinical data support a role for TLS in modulating immunity in the tumor microenvironment. However, there appear to be varied functions of TLS, potentially based on their structure or location in relation to the tumor or the origin or location of the tumor itself. Understanding more about TLS development, composition, and function may offer new therapeutic opportunities to modulate antitumor immunity.

Aging leads to inferior Achilles tendon mechanics and altered ankle function in rodents

Spontaneous rupture of the Achilles tendon is increasingly common in the middle aged population. However, the cause for the particularly high incidence of injury in this age group is not well understood. Therefore, the objective of this study was to identify age-specific differences in the Achilles tendon-muscle complex using an animal model. Functional measures were performed in vivo and tissues were harvested following euthanasia for mechanical, structural, and histological analysis from young, middle aged, and old rats. Numerous alterations in tendon properties were detected across age groups, including inferior material properties (maximum stress, modulus) with increasing age. Differences in function were also observed, as older animals exhibited increased ankle joint passive stiffness and decreased propulsion force during locomotion. Macroscale differences in tendon organization were not observed, although cell density and nuclear shape did vary between age groups. Muscle fiber size and type distribution were not notably affected by age, indicating that other factors may be more responsible for age-specific Achilles tendon rupture rates. This study improves our understanding of the role of aging in Achilles tendon biomechanics and ankle function, and helps provide a potential explanation for the disparate incidence of Achilles tendon ruptures in varying age groups.

Effects of a respiratory functional training program on pain and sleep quality in patients with fibromyalgia: A pilot study

OBJECTIVE

To evaluate the effect of 8-week respiratory functional training program on pain tolerance, sleep, and urinary antioxidant and cortisol levels in 18 patients with fibromyalgia.

METHODS

Participants underwent a 12-week intervention: 4 weeks as control and 8 weeks of breathing exercises. Pain tolerance assay was done by using an algometer, whereas sleep quality was evaluated by actigraphy and by the Pittsburgh Sleep Quality Index. Cortisol and antioxidant levels were determined using commercial assay kits.

RESULTS

Increases in the pain tolerance threshold were detected in the occiput point after one month of intervention as well as in the low cervical and second rib points after one and two months. Actigraphy revealed a decrease in sleep latency, whereas sleep questionnaire showed improvements in sleep quality, sleep duration and sleep efficiency. No changes in cortisol and antioxidant levels were detected.

CONCLUSION

The 8-week breathing exercise intervention reduced pain and improved sleep quality.

CD49a and CD103 expression on tumor infiltrating lymphocytes in B16-OVA tumors depends on location and is correlated with a naive phenotype

Tissue resident memory (TRM) cells are found in certain peripheral tissues long after resolution of infections that generate them. TRM formation is induced by TGFβ and has been associated with upregulation of CD49a and CD103. Interaction of CD49a and CD103 with their respective ligands is thought to allow long term persistence of TRM cells in peripheral tissues. In melanoma patients, increased expression of CD49a and CD103 has been observed on tumor infiltrating lymphocytes (TIL) compared to PBMCs. These phenotypic similarities suggest that a subset of TIL might function as TRM. However, the impact of continuous antigen presentation and/or differential TGFβ expression levels on this property of TIL is currently unknown. Here we demonstrate that, in B16-OVA melanoma tumors, CD49a and CD103 expression on CD8 TILs is upregulated compared to lymph node (LN) derived CD8 T cells from non-tumor bearing mice. Additionally, relative expression of CD49a and CD103 differs between subcutaneous and intraperitoneal tumors. The capacity of T cells to persist in tumors thus potentially changes based on tumor location, which may be dependent on TGFβ levels. In contrast to LN of non-tumor bearing mice, CD103 is expressed on 50–90% of LN CD8 T cells in tumor bearing mice. Furthermore, CD103+CD8 TILs have a more naïve phenotype, whereas CD103neg CD8 TILs mainly express memory/effector T cell markers. The opposite is observed when T cells are activated in vitro. These data suggest that CD103+CD8 T cells in tumors are largely due to a tumor induced systemic induction of CD103 on naïve T cells, rather than intratumoral TRM differentiation. The importance of CD103 in retaining naïve T cells for functional differentiation within the tumor remains to be established.

Regulation of peripheral node addressin in tumor-associated CD31+ vascular endothelial cells

Naïve T cells use peripheral node addressin (PNAd), normally found on lymph node (LN) high endothelial venules (HEV), to traffic into lymphoid organs. We previously reported that the vasculature of murine tumors expressed PNAd and CCL21, which supports infiltration and intratumoral activation of naïve T cells, in turn delaying tumor growth. PNAd expression on tumor vasculature depends on effector CD8+ T cells that secrete LTα3, which signals through TNFR on tumor-associated CD31+ endothelial cells. PNAd expression is low on tumor vasculature, suggesting that it might be regulated differently than PNAd on HEV. Using RT-qPCR, we found that most of the enzymes responsible for PNAd synthesis are expressed comparably in CD31+ cells from tumors and LN. However, the primary sulfotransferase responsible for the generation of the 6-sulfo sialyl Lewis X structure on PNAd HEV, GlcNAc6ST-2, is minimally expressed in tumors. Tumor CD31+ cells expressed equivalent levels of GlcNAc6ST-1, suggesting that it is responsible for low-level PNAd expression. Of the scaffolding proteins that make up PNAd, GlyCAM-1 was minimally expressed in tumor CD31+ cells, whereas all others were expressed comparably. To identify the components of PNAd biosynthesis in tumor CD31+ cells that are controlled by LTα3-TNFR signaling, we evaluated tumors from WT and TNFR1/2KO mice. GlyCAM-1 was the only assessed PNAd component that was ablated in TNFR1/2KO tumors. However, based on transcript levels, GlyCAM-1 accounts for only about 10% of the PNAd scaffolding proteins in tumor CD31+ cells. This suggests that TNFR signaling regulates additional PNAd biosynthetic components yet to be examined, or that it regulates one or more components at the level of protein translation.

Melatonin increases the survival time of animals with untreated mammary tumours: Neuroendocrine stabilization

The aim of this study was to evaluate the therapeutic effect of melatonin, the main hormone of the pineal gland, on rats with advanced and untreated mammary tumours. Mammary tumours were chemically induced in Sprague-Dawley rats with the carcinogen 9,10-dimethyl-1,2-bezanthracene (DMBA). After the appearance of tumours the effect of melatonin (5 mg/ml per rat per day) was then evaluated on the survival time, tumour multiplicity, and tumour volume until the death of the animals. In addition, the variations in prolactin, noradrenaline and adrenaline concentrations, and in the percentage of NK cells were evaluated after one month of the treatment with melatonin. Daily administration of melatonin increased significantly the survival time of tumour-bearing animals (p<0.05 with respect to the control non-melatonin-receiving rats). The increased survival time did not correlate, however, with changes in either tumour multiplicity or tumour growth rate. Animals with mammary tumours exhibited an increase (p<0.05 with respect to healthy animals) in prolactin and catecholamine concentrations. The administration of melatonin stabilized the hormone levels, returning them to those in the basal-healthy animals. Rats with mammary tumours also presented lower percentages of NK cells, which were not increased by the administration of melatonin. The results strongly suggest that melatonin per se is beneficial during advanced breast cancer. It increases survival time, maybe by improving the homeostatic and neuroendocrine equilibrium which is imbalanced during advanced breast cancer.

Physiological concentrations of melatonin and corticosterone in stress and their relationship with phagocytic activity

The aim of the present work was to investigate the possible connection between melatonin, corticosterone and the nonspecific immune response under both basal and stressed conditions. The concentrations used in the present study were as determined in an earlier work, and corresponded to the minimum and maximum concentrations of the hormones melatonin and corticosterone over one circadian cycle in mice subjected to stress and in a basal group of mice. The concentrations were 15 pg/ml and 90 pg/ml of melatonin and 50 ng/ml and 200 ng/ml of corticosterone for incubations of the basal group macrophages, and 15 pg/ml and 70 pg/ml and 200 ng/ml and 500 ng/ml of melatonin and corticosterone, respectively, for incubations of macrophages from the group of stressed mice. The results indicate that corticosterone stimulates antigen ingestion at all physiological doses tested in the macrophages from the unstressed mice. The greatest phagocytic stimulation was obtained in macrophages from mice in a basal situation, and which had been incubated with the diurnal concentrations of the two hormones (maximum corticosterone 200 ng/ml; minimum melatonin 15 pg/ml). When the macrophages were from stressed mice, neither corticosterone nor melatonin led to any change in their phagocytic activity.

Melatonin and aging: in vitro effect of young and mature ring dove physiological concentrations of melatonin on the phagocytic function of heterophils from old ring dove

We have studied the circadian rhythm of melatonin in the ring dove (Streptopelia risoria) for different age groups: young (1-1.5 years), mature (3-4 years) and old animals (>8 years). Melatonin levels were determined by radioimmunoassay. Results showed a significant decline in plasma melatonin levels in old animals when compared with the concentrations observed in the other two age groups, in which maximum (nocturnal) concentrations were 300 pg/ml and minimum (diurnal) concentrations were 50 pg/ml. We analyzed the in vitro effect of the physiological concentrations found in young and mature animals on the heterophils obtained from old animals, evaluating the capacity for ingestion and destruction of Candida albicans, and the oxidative metabolism associate to phagocytosis by determining the superoxide anion levels. Melatonin induced an increase in both the phagocytosis index and the candidicide capacity. This effect was dose-dependent. In relation with the oxidative metabolism, a decline in superoxide anion levels after incubation with both concentrations of the hormone was observed. Thus our results corroborate in this avian species the decline in plasma melatonin levels with advanced age, as well as the enhancing effect of physiological concentrations of melatonin on the phagocytic function.

Enhanced chemotaxis of macrophages by strenuous exercise in trained mice: thyroid hormones as possible mediators

Exercise modulates the macrophage activity via 'stress hormones'. Three experiments were performed. (1) The effect of strenuous exercise performed by trained mice on macrophage chemotactic capacity was evaluated; (2) peritoneal macrophages from control mice were incubated with plasma from exercised mice or control mice and the differences in chemotaxis were measured; (3) changes in plasma T3 and T4 levels after exercise were measured, and the effect of incubation with the post-exercise levels of plasma T3 and T4 on chemotaxis was then studied in vitro. A 10(4)-fold higher concentration of each hormone was also evaluated. Exercise provoked an increase in chemotaxis (104 +/- 35 vs. 47 +/- 11 in controls). Incubation with plasma from exercised mice led to an increased level of chemotaxis. Incubation with concentrations of T3 and T4 similar to those observed in post-exercise plasma (T3, 2.3 nmol l(-1); T4, 84 nmol l(-1)) enhanced chemotaxis with respect to incubation with the basal concentrations of the hormones in control animals. A 10(4)-fold concentration of T4 reversed this effect. It is concluded that thyroid hormones stimulate macrophage chemotaxis. Also, these data support the hypothesis that thyroid hormones may be involved in exercise-induced stimulation of chemotaxis.

Suppression of both basal and antigen-induced lipid peroxidation in ring dove heterophils by melatonin

There have been several findings recently concerning melatonin as a free radical scavenger and general antioxidant. For instance, in bird heterophils we found that 100 microM of melatonin decreases superoxide anion levels and modulates superoxide dismutase activity. This paper sought to study the effect of melatonin upon induced oxidative damage in heterophils of the ring dove (Streptopelia risoria). The concentration of malonaldehyde (MDA) as an index of induced oxidative damage to lipid membranes was tested by colorimetric assay. A heterophil suspension was co-incubated with and without inert particles (latex beads) as material to be phagocytosed, both alone and in combination with 100 microM of melatonin. Measurements were made at the basal time (0 min), as well as at 15, 30, 45, and 60 min. Protein concentrations were determined by a standardized method using bovine serum albumin as standard. Results are expressed as nmol MDA/mg prot. Melatonin clearly reduced the production of MDA, an index of lipid peroxidation. It also annulled the enhancement of MDA levels produced by latex beads. Both effects were observed at all the times studied. In conclusion, our findings again show that the neurohormone melatonin could be useful as an effective pharmacological antioxidant.

Serum hemolytic and bactericidal activity in breast and formula-fed infants

Whether formula or breast feeding influences the functional activity of the complement system from birth to three months of age has been studied. The classical pathway was evaluated by assessing hemolytic activity, based on the capacity of the intact complement system to lyse sheep erythrocytes when coated with specific antibodies. The bactericidal activity of the serum against Staphylococcus aureus and Escherichia coli was used to evaluate the alternative complement pathway. Sera were obtained from neonates (40 +/- 2 weeks of gestation), and one-month or three-month old infants, fed either breast or formula. Control serum was obtained from healthy adults between 22 and 30 years of age. The hemolytic capacity of serum from breast-fed infants of one month and three months of age was significantly greater than that of the serum from infants which had been fed formula milk.

A study of the role of corticosterone as a mediator in exercise-induced stimulation of murine macrophage phagocytosis

1. It is generally accepted that physical activity provokes changes in the immune system. Previous studies have demonstrated that the stress of physical activity (swimming until exhaustion) increases the phagocytic activity of peritoneal macrophages. However, the precise mechanisms remain unknown. 2. Two experiments were performed in the present study. (A) Peritoneal macrophages from control mice were incubated with plasma from three different groups of mice: (1) mice subjected to swimming until exhaustion with no previous training, (2) mice subjected to the same activity but with 1 month of training (30 min day-1), and (3) a control (non-exercised) group. The differences in the resulting phagocytic (attachment and ingestion) capacity were measured. (B) Changes in the concentration of plasma corticosterone after exercise were also measured, and the effect of incubation with the postexercise plasma corticosterone level on the phagocytic activity of peritoneal macrophages was then studied in vitro. 3. The results were: (A) incubation with plasma from both groups of exercised mice (with and without previous training) led to increased levels of phagocytic capacity (number of C. albicans cells ingested per 100 macrophages). (B) Incubation with a corticosterone concentration of 0.72 mumol l-1 (similar to that observed in plasma immediately after exercise) raised the phagocytic capacity (144 +/- 12 after incubation with 0.72 mumol l-1 vs. 93 +/- 19 after incubation with 0.24 mumol l-1). This increase was also significantly greater than that observed with 7.2 mumol l-1 corticosterone. 4. It is concluded that corticosterone may mediate the increased phagocytic function of peritoneal macrophages induced by exercise.

Intracellular activity of both teicoplanin and vancomycin against Staphylococcus aureus in human neutrophils

The effects in vitro of both teicoplanin and vancomycin of blood peripheral human neutrophils have been studied by assays of antibiotic uptake and intracellular killing of previously phagocytosed Staphylococcus aureus. The effects of vancomycin and teicoplanin (a novel glycopeptide antibiotic), at the therapeutic concentrations reached in plasma (10, 25, 50, 75 and 100 mg/l) and at different times of incubation (5, 15, 30 and 60 min) were studied. The results indicate that: (1) the bactericidal effect of neutrophils increases with incubation time, (2) in the presence of both teicoplanin and vancomycin, the number of CFU/ml of intraphagocytic S. aureus declines with both increasing incubation time and exposure dose of the antibiotics and (3) at 100 mg/l of teicoplanin there is a significant increase in the percentage inhibition of S. aureus growth at all the times studied.

Increased phagocytic activity of polymorphonuclear leukocytes during pregnancy

Many immunological parameters are depressed during pregnancy. For this reason, an evaluation was made of the phagocytic activity, representing non-specific immunity, of polymorphonuclear leukocytes from pregnant women. The cells were isolated from heparinized venous human blood of pregnant women of 10 or more weeks' gestation and non-pregnant women (controls), 20-30 years old. The results indicate that the phagocytosis of inert particles (latex beads) does not significantly change in pregnancy. However, the attachment, ingestion and digestion of Candida albicans significantly increased in pregnancy, with the greatest difference from controls being in the second trimester. These findings suggest that the phagocytic activity in pregnant women is enhanced and that this increased non-specific immunity may compensate in part for weakened specific immunity of the maternal host.

Effect of age on adherence and chemotaxis capacities of peritoneal macrophages. Influence of physical activity stress

The aim of the present research was to study the effects of age on the adherence and chemotaxis capacities of macrophages. Macrophages were obtained from the peritoneum of young and old mice (young, 12 +/- 4 weeks; old, 68 +/- 6 weeks) and young and mature guinea pigs (young, 12 +/- 1 weeks; mature, 108 +/- 2 weeks). Adherence of macrophages was evaluated with a plastic adherence technique, and chemotaxis in a Boyden chamber. The macrophages from old animals showed a higher adherence capacity (studied at 10, 40 and 60 min of incubation), and lower chemotaxis capacity in both mice and guinea pigs. The effect of physical activity stress (swimming until exhaustion) was also studied, both with and without a previous training program, on the adherence and chemotaxis of macrophages from young and old mice. While the physical activity stress (detected by the increase of the serum corticosterone concentration) did not induce changes in adherence or chemotaxis of peritoneal macrophages from young mice, in the old mice, there was a decrease in adherence and an increase in chemotaxis.

In vitro effect of cefoxitin on phagocytic function and antibody-dependent cellular cytotoxicity in human neutrophils

The effects in vitro of Cefoxitin, a beta-lactam antibiotic, at a concentration of 50 micrograms/ml (similar to a therapeutic level in plasma) on each step of the phagocytic process, in addition to antibody-dependent cellular cytotoxicity (ADCC) of blood peripheral human neutrophils have been studied. The antibiotic produced a significant stimulation of adherence capacity, chemotaxis, attachment of Candida albicans to neutrophils and phagocytosis of Candida albicans (with serum, decomplemented serum or without serum), ingestion of inert particles (latex beads), microbicidal activity, and digestion capacity of the ingested material [measured by nitroblue tetrazolium (NBT) reduction]. Moreover, cefoxitin (50 micrograms/ml) demonstrated chemoattractant activity for neutrophils. ADCC was also increased by this antimicrobial agent. These results therefore suggest that a therapeutic concentration of cefoxitin may enhance microbicidal and cytotoxic functions of a pivotal human phagocytic cell: the neutrophil.

Stimulation of phagocytic processes and antibody-dependent cellular cytotoxicity of human neutrophils by cefmetazole

Interactions between antimicrobial agents and phagocytic cells, especially neutrophils, have a potential role in the treatment of infections. The in vitro effects of cefmetazole, a novel beta-lactam antibiotic, at a therapeutic concentration reached in plasma (50 micrograms/ml) on phagocytic and cytotoxic functions of human neutrophils have been studied. In human neutrophils, adherence capacity to nylon fiber and to substrate, chemotaxis, attachment to and ingestion of Candida albicans (with serum, with decomplemented serum and without serum), ingestion of inert particles (latex beads), candidicidal activity and superoxide anion production were all stimulated by cefmetazole. Cefmetazole at this dose was a chemotactic agent for neutrophils. Antibody-dependent cellular cytotoxicity (ADCC) was also increased by this anti-microbial agent.

Phagocytic function of blood neutrophils in sedentary young people after physical exercise

The effect of exhaustive running exercise on the phagocytic function of blood polymorphonuclear neutrophils in sedentary young men and women has been studied. Adherence capacity to the endothelium, spontaneous mobility, chemotaxis and ingestion of Candida albicans were not modified after physical exercise. However, opsonization of Candida albicans as well as candidicide power increased significantly in men and women after exercise. The immediate advantages of physical exercise on the phagocytic immune response is discussed.

Mechanisms of action involved in the chemoattractant activity of three beta-lactamic antibiotics upon human neutrophils

The effects produced by three beta-lactamic antibiotics (N-formimidoyl thienamycin or imipenem, cefmetazole and cefoxitin) in vitro on protein carboxylmethylation, cAMP and cGMP levels in human polymorphonuclear neutrophils were studied. These antibiotics (50 micrograms/mL) exhibited chemoattractant activity for phagocytic cells and produced a fast (0.5 min) and significant stimulation of protein carboxylmethylation. They also increased intraphagocytic cGMP levels although no changes in cAMP levels were observed. Since the involvement of the above-mentioned mechanisms in leukotaxis have been established, the stimulation of neutrophil chemotaxis by the three antibiotics studied could possibly be mediated by one or more of these mechanisms.

Phagocytic function and antibody-dependent cellular cytotoxicity of human neutrophils in the presence of N-formimidoyl thienamycin

The efficacy of an antibiotic in the treatment of bacterial infections depends upon the interactions of the drug, bacteria and phagocytes. We have studied "in vitro" the effect of N-formimidoyl thienamycin (Imipenem), a novel beta-lactamic antibiotic, on the phagocytic function and antibody-dependent cellular cytotoxicity of human neutrophil leukocytes. The incubation of these cells with 50 micrograms/ml of Imipenem similar to the therapeutic levels reached in plasma results in an increase of their adherence capacity to nylon fiber and to substrate, induced mobility or chemotaxis, opsonization, phagocytosis of Candida albicans (with serum, with decomplementarized serum and without serum) and latex beads, candidicidal power and the capacity of NBT reduction. Imipenem at this dose also presents chemoattractant power for neutrophils and enhances the antibody-dependent cellular cytotoxicity (ADCC).

In vitro and in vivo effects of Imipenem on phagocytic activity of murine peritoneal macrophages

Imipenem, a new antibiotic beta-lactam, and Tienam (an Imipenem/Cilastatine combination) have been studied in vitro and in vivo respectively, in the phagocytic function of macrophages. In this paper we have seen the variations produced by 50 mg/l of Imipenem and 120 mg/kg of Tienam in the adherence, spontaneous mobility, chemotaxis, opsonization, phagocytosis of Candida albicans and latex beads, candidicid effect and nitroblue tetrazolium (NBT) reduction in peritoneal macrophages from BALB/C mice. This antibiotic significantly increases in vitro and in vivo the adherence, spontaneous mobility and chemotaxis, phagocytosis of latex beads and the digestion of ingested material (nitroblue tetrazolium reduction) in the above-mentioned cells. The number of Candida albicans opsonized and ingested by the macrophages is not modified in the presence of Imipenem, and neither is the candidicid effect.

Effects of acetylsalicylic acid on the phagocytic function of human polymorphonuclear leukocytes in vitro

1. In this paper acetylsalicylic acid (aspirin), an anti inflammatory drug, was studied in vitro at doses of 50, 100, 200 and 500 mg/l to see its effects on adherence, chemotaxis, spontaneous mobility, phagocytosis, candidicide power, nitrobule tetrazolium (NBT) reduction as well as the incorporation and metabolism of arachidonic acid in human polymorphonuclear neutrophils (PMNns). 2. Aspirin significantly stimulated neutrophil adherence to nylon fiber at all the doses used, with a correlation between the doses used and the adherence indices found. 3. At the therapeutic dose (100 mg/l) aspirin brings about a significant increase of chemotaxis, but reduces this property at the highest dose (500 mg/l). On the other hand, spontaneous mobility is not altered except with the 500 mg/l dose of aspirin which produces a significative decrease. 4. The ingestion of Cándida albicans by PMNns is significant at the therapeutic dose; the candidicide power is not modified with any of the doses used with 100 mg/l of aspirin nitroblue tetrazolium (NBT) reduction is significantly increased. 5. No changes are observed in the incorporation of arachidonic acid or in the release of its metabolites.

Effects of cefmetazol, cefoxitin and imipenem on polymorphonuclear leukocytes

1. We have investigated the effects produced in vitro by Cefmetazol, Cefoxitin and Imipenem on the chemotaxis, spontaneous mobility, adherence, phagocytosis and candidicide power of human polymorphonuclear neutrophils (PMNs). 2. The three antibiotics tested significantly stimulated the adherence of neutrophils to nylon fibre at doses either equal (50 mg/l) or superior (500 mg/l) to the therapeutic one. 3. Cefmetazol, Cefoxitin and Imipenem bring about a maximum increase of chemotaxis at the therapeutic dose, whereas the spontaneous mobility diminishes with any one of the doses used. 4. The capacity of the PMNs to phagocytize and produce lysis of Candida albicans is increased in Cefmetazol with therapeutic doses. Cefoxitin produced an increased lysis of candidas.