Overview of the Soluble and Membrane-bound Tumor Factors Limiting NKmediated Immune Surveillance

Many evidences suggest that NK cells are effective in patrolling for and eliminating tumors in their onset phase, but hardly limit the progression of large established solid tumors. Beside the transition of tumor cells towards a more aggressive phenotype, the NK cell efficacy might be limited by a complex immunosuppressive milieu present in the tumor microenvironment. Indeed, different mechanisms damping NK cell function have been shown in these last years. These include a plethora of tumor-derived immunomodulatory soluble factors (TGF-\u3b2, MIF, adenosine, LKynurenin, PGE2) as well as soluble ligands (MICA, ULBP-2, PVR, B7-H6) that compete with membrane-bound tumor ligands for binding to activating NK receptors. During NK-tumor cell contact the NK cell function can also be inhibited by the engagement on NK cells of different inhibitory receptors. The specific ligands might be either constitutively expressed at the tumor cell surface (HLA-I, B7-H3, PVR) or de novo induced/up-regulated (PD-Ls) by immunostimulatory factors (IFN-\u3b3, TNF-\u3b1). These are largely released during the active phases of the immune responses and exert an unwanted side effect called \u201ctumor adaptive immune resistance\u201d. This review aims to summarize the best-known molecular mechanisms that, at various times and in different ways, can limit the efficacy of the NK-mediated immune surveillance of tumors

Molecular Mechanisms Directing Migration and Retention of Natural Killer Cells in Human Tissues

A large body of data shows that Natural Killer (NK) cells are immune effectors exerting a potent cytolytic activity against tumors and virus infected cells. The discovery and characterization of several inhibitory and activating receptors unveiled most of the mechanisms allowing NK cells to spare healthy cells while selectively attacking abnormal tissues. Nevertheless, the mechanisms ruling NK cell subset recirculation among the different compartments of human body have only lately started to be investigated. This is particularly true for pathological settings such as tumors or infected tissues but also for para-physiological condition like pregnant human uterine mucosa. It is becoming evident that the microenvironment associated to a particular clinical condition can deeply influence the migratory capabilities of NK cells. In this review we describe the main mechanisms and stimuli known to regulate the expression of chemokine receptors and other molecules involved in NK cell homing to either normal or pathological/inflamed tissues, including tumors or organs such as lung and liver. We will also discuss the role played by the chemokine/chemokine receptor axes in the orchestration of physiological events such as NK cell differentiation, lymphoid organ retention/egress and recruitment to decidua during pregnancy

Analysis of morphological variables and arterialization in the differential diagnosis of hepatic nodules in explanted cirrhotic livers

BACKGROUND: Many terminologies have been given to dysplastic hepatocellular nodules, which are preneoplastic lesions. In 1995, the International Working Party meeting established the nomenclature and morphological criteria for hepatocellular nodular lesions. Nevertheless, an unequivocal differential diagnosis is sometimes difficult, particularly among large regenerative nodules, dysplastic nodules and hepatocellular carcinoma. Angiogenesis is observed during hepatocarcinogenesis and the presence of the isolated arteries may help to discriminate these nodules. The relevance of the International Working Party histological variables and presence of the isolated arteries were analyzed with regard to the diagnosis of large regenerative nodules, low and high grade dysplastic nodules and hepatocellular carcinoma, in order to evaluate which have a real contribution in such diagnoses. METHODS: One hundred and seven nodular hepatocellular lesions over 5 mm (or smaller nodules with a different color) from explanted cirrhotic livers were analyzed and classified following the criteria of the International Working Party. Classifications were as follows: large regenerative nodules, low grade dysplastic nodules, high grade dysplastic nodules and hepatocellular carcinoma. The presence of isolated arteries (not related to the portal tracts or fibrosis) was verified for the nodules. RESULTS: Among the 107 nodular lesions studied, 17 were classified as large regenerative nodules, 38 as low grade dysplastic nodules, 28 as high grade dysplastic nodules and 24 as hepatocellular carcinoma. The most relevant International Working Party variables in the differential diagnosis of the nodules were cellularity, trabeculae thickness, cytoplasmic staining, nuclear atypia, pseudoacinar pattern, portal tracts, nucleocytoplasmic ratio and mitosis. The isolated arteries, identified by hematoxylin and eosin staining, were important discriminating between two groups: low grade lesions (large regenerative nodules/low grade dysplastic nodules) and high grade lesions (high grade dysplastic nodules/hepatocellular carcinoma) (P < 0.001). CONCLUSION: The International Working Party criteria allow for the classification of the majority of hepatocellular nodules. However, other features such as cytoplasmatic tintorial affinity and pseudoacinar pattern may contribute to these diagnoses. The finding of isolated arteries in a nodular lesion should be investigated carefully, since the nodule could be a dysplastic lesion or hepatocellular carcinoma

Novel Immunoregulatory Functions of IL-18, an Accomplice of TGF-\u3b21

TGF-\u3b21 is a pleiotropic factor exerting a strong regulatory role in several cell types, including immune cells. In NK cells it profoundly alters the surface expression of crucial activating and chemokine receptors. To understand which soluble signals might better contrast these effects, we cultured human NK cells in the presence of TGF-\u3b21 and different innate and adaptive cytokines, generally referred as "immunostimulatory". These included IL-2, IL-15, IL-21, IL-27, and IL-18. Unexpectedly, IL-18 strengthened rather than contrasting important TGF-\u3b21-mediated functions. In particular, IL-18 further reduced the expression of CX\u2083CR1 and NKp30, leading to the virtual abrogation of the triggering capability of this activating receptor. Moreover, IL-18 further increased the expression of CXCR4. The IL-18-mediated additive effect on NKp30 and CXCR4 expression involved transcriptional regulation and activation of MEK/ERK and/or p38MAPK. A proteomic approach quantified both surface and intracellular proteins significantly modified in cytokine-treated NK cells, thus giving global information on the biological processes involving TGF-\u3b21 and IL-18. Our data support the concept that IL-18 may have a different behavior depending on the type of soluble factors characterizing the microenvironment. In a TGF-\u3b21 rich milieu such as tumors, it may contribute to the impairment of both NK cells recruitment and killing capability

Clinical features of respiratory syncytial virus bronchiolitis in an infant: rapid and fatal brain involvement

BACKGROUND: Respiratory Syncytial Virus (RSV) infection is a significant cause of bronchiolitis and pneumonia, mostly responsible for hospitalization and infant death worldwide. However, in recent years the importance of extrapulmonary RSV manifestations, especially at neurological level, have become evident. Seizures, lethargy, ataxia and status epilepticus are suggestive of brain involvement, but also in their absence a direct neurological damage RSV-related need to be evaluated. CASE PRESENTATION: A 40-day old male infant was admitted to the Emergency Department with severe bronchiolitis and dyspnea. The patient was reported to be coughing for a week with a vomiting episode in the previous two days. The nasopharyngeal swab confirmed the diagnosis of RSV infection and blood gas test showed hypoxemia and respiratory acidosis. For these reasons, the patient was provided with oxygen therapy. A few hours later, after an initial improvement in clinical parameters, a worsening of respiratory dynamics occurred and the patient was prepared for endotracheal intubation, but in the meantime death occurred. During all the observation period in the Emergency Room, no signs of neuropathological damage were evident. Post mortem examination showed lungs congestion with alveolar atelectasis and white matter degradation with severe edema at brain level. Microbiological analysis performed on autoptic samples confirmed the presence of RSV genome in tracheobronchial aspirate, meningeal swabs, pericardic and abdominal fluids, lung and brain biopsies. CONCLUSIONS: RSV is usually associated with respiratory diseases, however, as reported by an increasingly number of studies, the systemic dissemination of virus during severe disease can lead to a sudden infant death. The clinical picture herein reported showed a severe bronchiolitis resulting in a fatal and underestimated cerebral involvement due to RSV neurotropic behaviour and underline the need for clinicians to pay more attention to neurological involvement of RSV infection, even in absence of cerebral damage evidence

Efficacy of chlorthalidone and hydrochlorothiazide in combination with amiloride in multiple doses on blood pressure in patients with primary hypertension : a protocol for a factorial randomized controlled trial

Background: Thiazide diuretics have demonstrated favorable blood pressure lowering efficacy, but the equivalent doses of their more common agents, chlorthalidone and hydrochlorothiazide, are still unclear. Further, concerns exist regarding adverse metabolic effects, which may be attenuated with the concomitant administration of a potassium-sparing diuretic, such as amiloride. This trial aims to investigate the efficacy of chlorthalidone and hydrochlorothiazide, in combination with amiloride at different doses, for initial management of patients with primary hypertension. Methods/design: This is a factorial (2 × 2) randomized double-blinded clinical trial comparing the association of a thiazide diuretic (chlorthalidone 25 mg/day or hydrochlorothiazide 50 mg/day) with a potassium-sparing diuretic (amiloride 10 mg/day or amiloride 20 mg/day) in patients with primary hypertension. The primary outcome will be the mean change from baseline in 24-h systolic and diastolic blood pressure measured by ambulatory blood pressure monitoring. The secondary outcomes will be the mean change from baseline in daytime and nighttime systolic and diastolic blood pressure measured by ambulatory blood pressure monitoring, mean change from baseline in systolic and diastolic blood pressure measured by office blood pressure, incidence of adverse events, variation of laboratory parameters, and proportion of patients who achieved blood pressure control. The follow-up will last 12 weeks. For a P alpha of 0.05, power of 80%, standard deviation of 9 mmHg, and absolute difference of 6 mmHg on systolic blood pressure on 24-h ambulatory blood pressure monitoring, it will be necessary to study a total of 76 patients. The sample size will be increased by 10% to compensate for losses, resulting in 84 patients being randomized. Discussion: Diuretics are pivotal drugs for the treatment of hypertension. Chlorthalidone and hydrochlorothiazide, in combination with amiloride in multiple doses, will be tested in terms of blood pressure lowering efficacy and safety. Since the intensity of blood pressure reduction is the major determinant of reduction in cardiovascular risk in hypertensive patients, this study will help to determine which combination of diuretics represents the most appropriate treatment for this population