Inhibitory checkpoints in human natural killer cells: IUPHAR Review 28

Immune checkpoint inhibitors have revolutionized cancer therapy leading to exceptional success. However, there is still the need to improve their efficacy in non‐responder patients. Natural killer (NK) cells represent the first line of defence against tumours, due to their ability to release immunomodulatory cytokines and kill target cells that have undergone malignant transformation. Harnessing NK cell response will open new possibilities to improve control of tumour growth. In this respect inhibitory checkpoints expressed on these innate lymphocytes represents a promising target for next‐generation immunotherapy. In this review, we will summarize recent evidences on the expression of NK cells receptors in cancer, with a focus on the inhibitory checkpoint programmed cell death protein 1 (PD‐1). We will also highlight the strength and limitations of the blockade of PD‐1 inhibitory pathway and suggest new combination strategies that may help to unleash more efficiently NK cell anti‐tumour response.

An outbreak of severe invasive meningococcal disease due to a capsular switched Neisseria meningitidis hypervirulent strain B:cc11

OBJECTIVES

The aim was to investigate an outbreak of invasive meningococcal disease (IMD) in Southern Sardinia.

METHODS

Epidemiological and microbiological investigations were performed. The latter included antimicrobial susceptibility testing and whole-genome sequencing (WGS).

RESULTS

Seven individuals with severe IMD were found to be infected with serogroup B (MenB) Neisseria meningitidis in the first quarter of 2018. Five of the seven cases (five males; mean age 19 years; range 18-21 years; CFR 40%) were due to a unique strain B:P1.5-1,10-8:F3-6:ST-11(cc11), probably switched from the hypervirulent C-cc11, as confirmed by WGS. All five patients had attended the same nightclub in the 2 weeks prior to symptom onset. Public health measures, including chemoprophylaxis of contacts and active immunization against MenB, were implemented.

CONCLUSIONS

We observed five IMD cases due to the same switched MenB strain. The hypervirulent B:P1.5-1,10-8:F3-6:ST-11(cc11) strain, probably switched from C-cc11, is of concern due to the observed high virulence and case fatality rates. All the patients shared the same place of probable exposure. The molecular characterization of the invasive strain allowed the outbreak to be confirmed, which was then controlled through timely public health action.

IL15 induces a potent antitumor activity in NK cells isolated from malignant pleural effusions and overcomes the inhibitory effect of pleural fluid

Natural Killer (NK) cells are capable of recognizing and killing cancer cells and play an important role in tumor immunosurveillance. However, tumor-infiltrating NK cells are frequently impaired in their functional capability. A remarkable exception is represented by NK cells isolated from malignant pleural effusions (PE) that are not anergic and, upon IL2-induced activation, efficiently kill tumor cells. Although IL2 is used in various clinical trials, severe side effects may occur in treated patients. In this study, we investigated whether also other clinical-grade cytokines could induce strong cytotoxicity in NK cells isolated from pleural fluid of patients with primary or metastatic tumors of different origins. We show that PE-NK cells, cultured for short-time intervals with IL15, maintain the CD56^bright phenotype, a high expression of the main activating receptors, produce cytokines and kill tumor cells in vitro similarly to those treated with IL2. Moreover, IL15-activated PE-NK cells could greatly reduce the growth of established tumors in mice. This in vivo antitumor effect correlated with the ability of IL15-activated PE-NK cells to traffic from periphery to the tumor site. Finally, we show that IL15 can counteract the inhibitory effect of the tumor pleural microenvironment. Our study suggests that IL15-activated NK cells isolated from pleural fluid (otherwise discarded after thoracentesis) may represent a suitable source of effector cells to be used in adoptive immunotherapy of cancer.

Identification of diverse innate lymphoid cells in human decidua

Innate lymphoid cells (ILCs) are developmentally related cells that play an important role in innate defenses and tissue remodeling. So far, only natural killer (NK) cells have been identified and functionally characterized in human decidua where they contribute to induction of immune suppression, neo-angiogenesis, and tissue building/remodeling. The presence of other ILC subsets in human decidua has not been yet characterized. Here we identify in human decidua, during early pregnancy, two subsets of decidual group 3 ILC (ILC3), including lymphoid tissue inducer (LTi)-like cells and natural cytotoxicity receptors (NCRs)(+)ILC3 and interferon-(IFN)γ-producing ILC1, different from NK cells. Decidual LTi-like cells produced interleukin -17 (IL-17) and tumor necrosis factor (TNF), while NCR(+)ILC3 released IL-22 and IL-8. Importantly, NCR(+)ILC3 and LTi-like cells established functional interactions with stromal cells. Decidual LTi-like cells differentiated into NCR(+)ILC3, whereas they marginally contributed to NK cell generation. Our data suggest that decidual ILC3 may play a role in innate defenses and in vessel and tissue building, thus contributing to maintenance of pregnancy.

Effect of serotonergic system on AVP secretion induced by physical exercise

The present study was undertaken in order to establish the possible involvement of serotonergic receptors in the control of physical exercise-stimulated vasopressin secretion. Twenty-one healthy men (divided in three groups of seven) underwent bicycle-ergometer tests until exhaustion: exercise control test (n=21), exercise plus ondansetron, selective 5-HT3 antagonist (n=7), exercise plus buspirone, selective 5-HT1A receptor agonist (n=7), exercise plus sumatriptan, selective 5-HT1D receptor agonist (n=7). AVP levels, physiological and biochemical variables were measured and compared during tests. Results showed that exercise-induced AVP rise did not change after the administration of buspirone and sumatriptan. In contrast, the administration of ondansetron significantly reduced physical exercise-induced AVP rise. Mean peak levels during physical exercise were 4.9 times higher than basal values in the control test and 2.6 times higher than basal values in the ondansetron plus exercise test. These data demonstrate that 5-HT3 serotonergic receptors at least partially mediate the AVP response to physical exercise. On the other hand, 5-HT1A and 5-HT1D serotonergic receptors do not appear to be involved in the control of AVP secretion during exercise.

Naloxone decreases the inhibitory effect of ethanol on the release of arginine-vasopressin induced by physical exercise in man

To establish whether ethanol and/or endogenous opioids play a role in the control of arginine-vasopressin (AVP) response to physical exercise, six healthy men underwent six bicycle-ergometer tests until exhaustion [exercise control test; exercise plus ethanol (50 of 110 ml proof whiskey orally), exercise plus naloxone (2 mg injected plus 5 mg infused or 4 mg injected plus 10 mg infused intravenously] or exercise plus ethanol plus naloxone). Plasma AVP levels, physiological and biochemical variables were measured during tests. Physiological and biochemical variables were similar in all tests. During the control test, exercise significantly increased plasma AVP levels, with a peak value five times higher than baseline. The AVP response to exercise was similar in the presence of naloxone, whereas it was abolished by ethanol. When ethanol tests were repeated in the presence of naloxone, at both lower and higher dose, ethanol inhibition on AVP secretion was only partial, with mean peak responses 2.5 times higher than basal values. Results indicate an ethanol involvement in regulation of the AVP response to physical exercise. Furthermore, naloxone-sensitive endogenous opioids appear to play a role in the mechanism underlying ethanol inhibitory action, but not in mediation of the AVP response to physical exercise.

Purification and HPLC-MS analysis of a naturally processed HCMV-derived peptide isolated from the HEK-293T/HLA-E+/Ul40+ cell transfectants and presented at the cell surface in the context of HLA-E

A new method for isolation and characterization of peptides presented in the context of the nonclassical human leukocytes antigen (HLA) class I molecule HLA-E was developed. A combination of different chromatographic steps coupled with electrospray mass spectrometry allowed us to detect the presence of small amounts of a naturally processed human Cytomegalovirus (HCMV)-derived peptide isolated from the HEK-293T/HLA-E+/UL40+ transfected cells of from HELA cell line. The peptide sequence was confirmed by tandem mass spectrometry (MS/MS). This approach provides a versatile and sensitive method for direct identification of MHC class I-binding peptides that might be derive from different pathogen or tumor-associated proteins.

Neurotensin pulmonary metabolism in normal and asthmatic subjects

BACKGROUND

The role of pulmonary metabolism of endogenous neurotensin (NT) in asthma is still unclear. Information on this subject in humans is scarce.

OBJECTIVES

Evaluation of the pulmonary metabolism of the endogenous NT in asthmatic subjects during symptom-free periods and after a methacoline challenge test and in healthy individuals.

METHODS

Ten asthmatic subjects (aged 34 to 70 years), diagnosed with extrinsic (n = 5), atopic (n = 3), and mixed asthma (n = 2), were compared to a group of 10 healthy individuals (aged 45 to 69 years). The asthmatic group of patients was evaluated with a PD20-FEV1 methacoline challenge test 3 days after a washout period from cessation of their regular medications. Two catheters were inserted in order to draw blood samples for the evaluation of NT concentration: one was inserted into the pulmonary artery and the other into the radial artery. The mean concentration of NT in pulmonary and systemic arterial blood, as well as the arteriovenous difference of NT and the absolute value of production rate [PR/m'], PR/m'/kg and PR/m'/m2 were calculated for each participant.

RESULTS

The mean neurotensin concentration in normal subjects was higher in mixed venous blood (pulmonary artery) than in systemic arterial blood (p < 0001). Similarly, mean NT mixed venous levels in asthmatic subjects was shown to be higher than mean NT levels in systemic arterial blood, before and after the bronchoconstriction with methacoline (p = 0.05 and p = 0.02, respectively). In contrast, the arterovenous difference and the mean values of PR of NT were similar in both groups.

CONCLUSIONS

Our findings suggest that (1) NT concentration in mixed venous blood changes in transit through the pulmonary parenchyma, indicating that the pulmonary parenchyma is an important site of NT metabolism; (2) Pulmonary clearance of NT is unaffected by cholinergic bronchoconstriction. Further clinical studies are needed in order to improve both the understanding and the therapeutic approach of the neurogenic process in asthmatic subjects.

Minimal handling and bronchopulmonary dysplasia in extremely low-birth-weight infants

Over the last 16 years a minitouch regime, i.e., nasal continuous positive airway pressure (n-CPAP) and/or nasal intermittent positive pressure ventilation (n-IPPV), together with a minimal intubation policy has been routinely used for the treatment of respiratory distress syndrome (RDS) in preterm infants. Only 1.39 (1 out of 72) of the extremely low-birth-weight babies admitted to our Neonatal Intensive Care Unit (NICU) and surviving for at least 36 weeks' postconceptional age developed bronchopulmonary dysplasia at 36 weeks (BPD 36-wk). The BPD-36 wk incidence observed in our population is significantly lower than expected (30%) from the literature (p=0.000002).

CONCLUSION

Our experience supports the effectiveness of the minitouch regime as a way to ventilate premature babies, reducing BPD risk.

[Lipid metabolism and atherosclerosis risk in renal diseases in pediatric age]

The pathophysiological events regarding the atherosclerotic processes are present already in early childhood. Various clinical trials confirm tight correlation between dyslipidemia and cardiac and cerebrovascular complications. Over the clinical dyslipidemia genetically determined, various systemic diseases can lead to anomalies of the lipidic metabolism. The determination and analysis of the lipidic pattern is essential during childhood and in particular in patients with renal disease for the increased risk of progressive failure of renal function and for the central role of kidney in lipidic homeostasis. Cardiovascular event is the most important cause of mortality in patients with end-stage renal disease. In children with nephrotic syndrome, renal failure, hemodialysis or after renal transplantation, an increase of the serum values of triglycerides, cholesterol, LDL, VLDL is generally observed. The presence of anomalies in lipidic pattern must be considered during the course of renal disease for preventing the progression of renal damage. Thus, the pharmacological therapy and diet permit to prevent the atherosclerotic events.

[Does B-mode ultrasound still have a role in the diagnosis of spermatic cord torsion? Findings in a pediatric series]

INTRODUCTION

Acute scrotum in the pediatric age is mainly related to surgical causes. Spermatic cord torsion and inguinoscrotal hernia must be ruled out first, because of the possible ischemic damage to gonadal tissue and therefore surgery is sometimes performed directly, thus representing also a diagnostic tool. Spermatic cord torsion is found in two age ranges, namely: the neonatal period, where it usually represents the evolution of an intrauterine process, and the peripubertal period, which is more frequent. An unquestionable and prompt diagnosis is particularly needed because of the extreme sensitivity of gonadal tissue to ischemia. In this particular field, color and power Doppler US, depicting gonadal flow, have greatly increased diagnostic imaging capabilities, which were previously limited to B-mode US.

MATERIAL AND METHODS

We examined 19 peripubertal patients with the diagnosis of spermatic cord torsion made on the basis of B-mode US and then confirmed with color Doppler.

RESULTS

We found two signs which can be considered highly suggestive of spermatic cord torsion: the spiral twist of spermatic vessels and the peculiar extent of reactive hydrocele, caused by the bell clapper anomaly of the vaginal sac.

CONCLUSIONS

The above US patterns are very helpful to diagnose spermatic cord torsion.

[Disseminated mucormycosis. A rare case in pediatric intensive care]

A rare case of disseminated mucormycosis occurred in a 3-year-old boy suffering from a 4th degree neuroblastoma, treated with chemiotherapy and broad-spectrum antibiotics is reported. The child was admitted in the pediatric intensive care unit after surgical debridement of a wide part of the bowel showing necrosis and vessel thrombosis. After the histological diagnosis of mucormycosis in the gastrointestinal tract and the echographic detection of multiple mycotic localizations in the liver and kidneys, a treatment with high-dose amphotericin B was carried out. At the same time, the occurrence of anaerobiosis and/or acidosis as well as hyperglycemia was avoided in order to prevent the hyphae growth. This therapeutic strategy has been successful in preventing the infection spread, so that after 10 months from the discharge from the intensive care unit the child is in good health and the liver and kidney lesions are unchanged.