Effector and regulatory events during natural killer–dendritic cell interactions

Summary:  The different cell types of the innate immune system can interact with each other and influence the quality and strength of an immune response. The cross talk between natural killer (NK) cells and myeloid dendritic cells (DCs) leads to NK cell activation and DC maturation. Activated NK cells are capable of killing DCs that fail to undergo proper maturation ('DC editing'). Encounters between NK cells and DCs occur in both inflamed peripheral tissues and lymph nodes, where both cell types are recruited by chemokines released in the early phases of inflammatory responses. Different NK cell subsets (CD56^brightCD16⁻ versus CD56⁺CD16⁺) differ in their homing capabilities. In particular, CD56^brightCD16⁻ NK cells largely predominate the lymph nodes. In addition, these two subsets display major functional differences in their cytolytic activity, cytokine production, and ability to undergo proliferation. NK cell functions are also greatly influenced by the presence of polarizing cytokines such as interleukin (IL)-12 and IL-4. The cytokine microenvironment reflects the presence of different cell types that secrete such cytokines in response to microbial products acting on different Toll-like receptors (TLRs). Moreover, NK cells themselves can respond directly to microbial products by means of TLR3 and TLR9. Thus, it appears that the final outcome of a response to microbial infection may greatly vary as a result of the interactions occurring between different pathogen-derived products and different cell types of the innate immunity system. These interactions also determine the quality and strength of the subsequent adaptive responses. Remarkably, NK cells appear to play a key role in this complex network.     

IL-21 induces both rapid maturation of human CD34+ cell precursors towards NK cells and acquisition of surface killer Ig-like receptors

The NK cell maturation from CD34(+) Lin(-) hematopoietic cell precursors is a complex process that requires the direct contact with stromal cells and/or the synergistic effect of different cytokines. In this study we show that IL-21 is capable of inducing an accelerated NK cell maturation when added to cultures of CD34(+) Lin(-) cells isolated from human cord blood supplemented with IL-15, Flt3-L and SCF. After 25 days of culture, 50% of CD56(+) cells expressed various NK cell markers including the NKp46 and NKp30 triggering receptors, the CD94/NKG2A inhibitory receptor and CD16. At day 35, substantial fractions of NK cells expressed KIR, CD8 and CD2, i.e. surface markers expressed by mature NK cells, that are virtually undetectable in developing NK cells cultured in the absence of IL-21. Remarkably, similar to mature NK cells all these markers were included in the CD56(dim) cell fraction, while the CD56(bright) population was only composed of CD94/NKG2A(-) and CD94/NKG2A(+) cells. Thus, IL-21 allows the induction of a full NK cell maturation in vitro and offers an important tool for dissecting the molecular mechanisms involved in different steps of NK cell maturation and in the acquisition of a mature KIR repertoire.     

Hyper immunoglobulin M syndrome due to CD40 deficiency: clinical, molecular, and immunological features

Summary: CD40 is a member of the tumor necrosis factor receptor family, which is expressed by a variety of cells including B cells, macrophages, dendritic cells, and other nonimmune cell types. CD40 activation is critical for B‐cell proliferation, immunoglobulin (Ig)‐isotype switching, and germinal center formation. In physiological conditions, the activation of CD40 occurs by binding to its natural ligand, CD154, which is expressed on activated T cells. The in vivo critical role of CD40–CD154 interaction on B‐cell differentiation and isotype switching is provided by the discovery that mutations in either CD40 or CD154 gene cause the hyper IgM syndrome, termed HIGM3 or HIGM1, respectively, characterized by very low levels of serum IgG, IgA, and IgE, with normal or elevated IgM, associated with a defective germinal center formation. Originally considered humoral primary immunodeficiencies, the clinical features and the defect of T‐cell priming, resulting from a defective T–B cell or dendritic cell interaction, is now considered as combined immunodeficiencies. In this article, we present a comprehensive overview of the clinical, genetic, and immunological features of patients with hyper IgM syndrome due to CD40 mutations.     

Genomic allelotyping for distinction of recurrent and de novo hepatocellular carcinoma after orthotopic liver transplantation.

Distinction between recurrent and de novo hepatocellular carcinoma (HCC) after orthotopic liver transplantation (OLT) bears important clinical and therapeutic implications. Techniques for molecular profiling of clinically suspected de novo and recurrent HCC are required since the histological/clinical discrimination of donor vs. recipient tumor origin is difficult. Multiple PCR amplification of 16 highly polymorphic short tandem repeat (STR) DNA sequences (routinely used for paternity and forensic assays) was applied in two patients who developed a second HCC after OLT. In both patients the technique provided reliable evidence that the two second HCC were recurrences of the primary tumor. Multiple STR genetic allelotyping is an effective tool for clear-cut discrimination of donor/recipient origin of a second HCC after OLT. Its application could be of great therapeutic relevance for such OLT patients.     

DTNBP1 haplotype influences baseline assessment scores of schizophrenic in-patients

Dysbindin gene (DTNBP1) has been associated with schizophrenia, but literature findings are inconsistent, and further analyses are required. This study is aimed to investigate if a set of DTNBP1 variations might influence clinic psychotic phenotype or treatment response in a sample of 240 Korean schizophrenic in-patients. Four variants have been selected (rs3213207; rs1011313; rs16876759; rs2619522) on the basis of previous findings of association with schizophrenia, bipolar disorder and antidepressant response. Single marker analysis gave marginal results. Haplotype analysis identified a significant association between A–A (rs3213207(A/G), rs1011313(A/G)) haplotype and lower PANSS total and positive scores at baseline (p = 0.01; 0.02) and at discharge (p = 0.008; 0.005). Covariate analysis revealed a more stable significant association between A–A haplotype and baseline scores. These results suggest a protective effect of A–A haplotype on psychotic positive symptoms at baseline.     

Metabolic fate of zetidoline,a new neuroleptic agent,in man

Summary Healthy volunteers administered orally a single dose (20 mg) of [2-¹⁴C]zetidoline, a new dopamine antagonist, exhibited rapid absorption of radioactivity with peak plasma levels of 250–300 ng/ml achieved in 1 h. The compound underwent intensive metabolic first-pass so that plasma radioactivity was represented mostly by two products, metabolite B endowed with neuroleptic activity, and metabolite D inactive, while unchanged zetidoline was not detected. Disappearance of radioactivity from plasma was rapid with a half-life of 1.78±0.20 h.The simultaneous assay of plasma prolactin showed increased levels of the hormone (+464% at the peak time) up to the 6th h after dosing, with plasma concentration profile which mimic those of metabolite B.The radioactive test-dose was eliminated mainly via the kidneys with an average urinary recovery of 84.7±1.7% in 4 days (73.4±1.1% within 8 h). The main urinary metabolite (metabolite G) and two minor ones (metabolites B and D) were purified and their structures assigned by IR, MS and NMR spectroscopy, they are: 1-(3-chloro-4-hydroxyphenyl)-3[2-(3,3-dimethyl-1-azetidinyl)ethyl]imidazolidin-2-one, metabolite B; 1-[2-(3,3-dimethyl-1-azetidinyl)ethyl]imidazolidin-2-one, metabolite D and the 4-O-sulphate ester of metabolite B, metabolite G.The metabolic fate of zetidoline in man follows the same phase I reactions demonstrated in rats and dogs, while the phase II reaction is sulphoconjugation instead of the glucuronidation observed in animals.     

Nutrigenomics and Nutrigenetics in Metabolic- (Dysfunction) Associated Fatty Liver Disease: Novel Insights and Future Perspectives

Metabolic- (dysfunction) associated fatty liver disease (MAFLD) represents the predominant hepatopathy and one of the most important systemic, metabolic-related disorders all over the world associated with severe medical and socio-economic repercussions due to its growing prevalence, clinical course (steatohepatitis and/or hepatocellular-carcinoma), and related extra-hepatic comorbidities. To date, no specific medications for the treatment of this condition exist, and the most valid recommendation for patients remains lifestyle change. MAFLD has been associated with metabolic syndrome; its development and progression are widely influenced by the interplay between genetic, environmental, and nutritional factors. Nutrigenetics and nutrigenomics findings suggest nutrition’s capability, by acting on the individual genetic background and modifying the specific epigenetic expression as well, to influence patients’ clinical outcome. Besides, immunity response is emerging as pivotal in this multifactorial scenario, suggesting the interaction between diet, genetics, and immunity as another tangled network that needs to be explored. The present review describes the genetic background contribution to MAFLD onset and worsening, its possibility to be influenced by nutritional habits, and the interplay between nutrients and immunity as one of the most promising research fields of the future in this context.     

Prenatal Exposure to BPA: The Effects on Hepatic Lipid Metabolism in Male and Female Rat Fetuses

Bisphenol A (BPA) is an organic chemical compound widely used for manufacturing plastics. BPA exposure originates principally from the diet, but it can also originate from dermal contact. In over 90% of individuals, including pregnant women, BPA is detectable in several body fluids. The effects of this exposure on the fetus are under active investigation in several research laboratories. The aim of our work was to study the impact of prenatal exposure to BPA in the liver of rat fetuses from a sex-dependent point of view. We particularly investigated the effects of prenatal BPA exposure on hepatic lipids because of their crucial role, not only for the liver, but also for the whole-body functions. Our results demonstrate that the liver of rat fetuses, in utero exposed to a very low dose of BPA (2.5 µg/kg/day), displays significant modulations with regard to proteins involved in cholesterol and fatty acid biosynthesis and trafficking. Moreover, an impact on inflammatory process has been observed. All these effects are dependent on sex, being observable only in female rat fetuses. In conclusion, this work demonstrates that maternal exposure to BPA compromises hepatic lipid metabolism in female offspring, and it also reveals the perspective impact of BPA on human health at doses currently considered safe.