Francesco Perna

Beneficial effects of leptin on obesity, T cell hyporesponsiveness, and neuroendocrine/metabolic dysfunction of human congenital leptin deficiency

The wide range of phenotypic abnormalities seen in the leptin-deficient ob/ob mouse and their reversibility by leptin administration provide compelling evidence for the existence of multiple physiological functions of this hormone in rodents. In contrast, information regarding the roles of this hormone in humans is limited. Three morbidly obese children, who were congenitally deficient in leptin, were treated with daily subcutaneous injections of recombinant human leptin for up to 4 years with sustained, beneficial effects on appetite, fat mass, hyperinsulinemia, and hyperlipidemia. Leptin therapy resulted in a rapid and sustained increase in plasma thyroid hormone levels and, through its age-dependent effects on gonadotropin secretion, facilitated appropriately timed pubertal development. Leptin deficiency was associated with reduced numbers of circulating CD4(+) T cells and impaired T cell proliferation and cytokine release, all of which were reversed by recombinant human leptin administration. The subcutaneous administration of recombinant human leptin has major and sustained beneficial effects on the multiple phenotypic abnormalities associated with congenital human leptin deficiency.

Selective capacity of metreleptin administration to reconstitute CD4+ T-cell number in females with acquired hypoleptinemia

Leptin is an adipocyte-derived hormone that controls food intake and reproductive and immune functions in rodents. In uncontrolled human studies, low leptin levels are associated with impaired immune responses and reduced T-cell counts; however, the effects of leptin replacement on the adaptive immune system have not yet been reported in the context of randomized, controlled studies and/or in conditions of chronic acquired leptin deficiency. To address these questions, we performed a randomized, double-blinded, placebo-controlled trial of recombinant methionyl-human leptin (metreleptin) administration in replacement doses in women experiencing the female triad (hypothalamic amenorrhea) with acquired chronic hypoleptinemia induced by negative energy balance. Metreleptin restored both CD4+ T-cell counts and their in vitro proliferative responses in these women. These changes were accompanied by a transcriptional signature in which genes relevant to cell survival and hormonal response were up-regulated, and apoptosis genes were down-regulated in circulating immune cells. We also observed that signaling pathways involved in cell growth/survival/proliferation, such as the STAT3, AMPK, mTOR, ERK1/2, and Akt pathways, were activated directly by acute in vivo metreleptin administration in peripheral blood mononuclear cells and CD4+ T-cells both from subjects with chronic hypoleptinemia and from normoleptinemic, lean female subjects. Our data show that metreleptin administration, in doses that normalize circulating leptin levels, induces transcriptional changes, activates intracellular signaling pathways, and restores CD4+ T-cell counts. Thus, metreleptin may prove to be a safe and effective therapy for selective CD4+ T-cell immune reconstitution in hypoleptinemic states such as tuberculosis and HIV infection in which CD4+ T cells are reduced.

Immune-metabolic profiling of anorexic patients reveals an anti-oxidant and anti-inflammatory phenotype ☆

CONTEXT Anorexia nervosa (AN) is an excessive form of calorie restriction (CR) associated with pathological weight loss and alterations of the immune system. However, AN patients seem to be protected from common viral infections. OBJECTIVES To investigate the metabolic and molecular adaptations induced by sustained extreme CR in the peripheral blood mononuclear cells (PBMCs) of patients with restrictive alimentary AN. DESIGN Inflammatory cytokines and adipokines were measured in 15 young (age range, 15-24 years) AN female patients and 20 age-matched healthy controls. Isolated PBMCs were immunophenotyped by flow cytometry, and glycolysis and mitochondrial respiration were determined by measuring the extracellular acidification and oxygen consumption rate. Stress resistance to H2O2 and the antioxidant transcriptional profile of PBMCs and human fibroblasts incubated with sera from AN patients were also determined. RESULTS Compared with controls, AN patients (BMI, 15.9±0.4 kg/m(2)) had significantly fewer leucocytes, lymphocytes and NK cells, lower serum concentrations of leptin, IGF-1 and sTNFR1, and higher levels of adiponectin, sCD40L and sICAM-1 (p<0.05). IL-1β, TNFα, and IL-6 produced by PBMC cultured with autologous serum for 48 h were significantly lower in AN patients than in controls (p<0.01). Moreover, glycolysis and mitochondrial respiration were lower, and the antioxidant transcriptional profile was higher in the PBMCs of AN patients. Fibroblasts cultured in serum from AN patients showed a 24% increase in resistance to H2O2 damage. CONCLUSIONS Extreme CR in AN patients is associated with a reduction in several immune cell populations, but with higher antioxidant potential, stress resistance and an anti-inflammatory status.

Allelic distribution of human leucocyte antigen in historical and recently diagnosed tuberculosis patients in Southern Italy

This study addresses the analysis of the human leucocyte antigen (HLA) allele distribution in 54 historical and in 68 recently diagnosed tuberculosis (TB) patients. The historical cohort was characterized by the presence of large fibrocavernous lesions effectively treated with therapeutic pneumothorax during the period 1950–55. Patients and healthy controls enrolled in the study were from the Campania region of southern Italy. No significant association between HLA alleles and TB in the population of recently diagnosed TB patients was observed. On the contrary, among the historical TB patients there was a strong association with an increased frequency of the HLA‐DR4 allele alone and/or in the presence of the HLA‐B14 allele (P = 0·000004; Pc = 0·0008), as well as with a decreased frequency of the HLA‐A2+,‐B14−,DR4− allele association (P = 0·00005; Pc = 0·01). In order to exclude any interference from age‐related factors, these results were confirmed by comparing the historical cohort of TB patients with an age‐matched healthy control population of the same ethnic origin (P = 0·00004; Pc = 0·008; and P = 0·0001; and Pc = 0·02, respectively).

Longitudinal assessment of immuno-metabolic parameters in multiple sclerosis patients during treatment with glatiramer acetate

OBJECTIVE We investigated the effect of glatiramer acetate (GA) on the modulation of immune cell subpopulations and serum levels of multiple immune/metabolic markers in patients with relapsing-remitting multiple sclerosis (RRMS) to understand whether the treatment with GA could induce a specific change in the immunometabolic asset of patients with RRMS. MATERIAL AND METHODS We performed an extensive peripheral blood immunophenotyping and measured serum levels of several parameters involved in the pathogenesis of RRMS and also relevant in the pathogenesis of metabolic syndrome and obesity such as leptin, soluble leptin-receptor (sLep-R), myeloperoxidase (MPO), soluble CD40 ligand (sCD40-L), soluble tumor necrosis factor-receptor (sTNF-R), monocyte chemoattractant protein 1 (MCP-1), soluble Inter-Cellular Adhesion Molecule-1 (sICAM-1) and osteoprotegerin (OPG), in 20 naïve-to-treatment RRMS patients and 20 healthy controls. We repeated these analyses over time at 6 and 12 months after starting GA treatment. RESULTS Our analysis showed that naïve-to-treatment RRMS patients had a lower number of CD16(+)CD56(+) NK cells, CD19(+) B cells, CD4(+) T cells co-expressing the MHC class II activation marker HLA-DR (CD4(+)DR(+)) and naïve CD4(+)CD45RA(+) T cells in basal conditions. GA treatment induced a specific and significant decrease of circulating CD19(+) B cells. Naïve-to-treatment RRMS patients also showed a significantly higher number of CD4(+) T cells with a memory phenotype (CD4(+)CD45RO(+)) whose peripheral frequency was not affected by GA treatment. These changes over time associated with a higher serum concentration of leptin and lower levels of MPO. GA treatment also reduced significantly the circulating levels of sCD40-L and sTNF-R overtime. CONCLUSIONS Our data suggest that the clinical outcome of GA treatment is associated with changes in immune cell subpopulations and modulation of specific immunometabolic markers. These data add substantial evidence of the immune modulating effect of GA during RRMS and could be of relevance in understanding the pathogenesis of disease and its follow-up.

Imbalance of circulating dendritic cell subsets in chronic obstructive pulmonary disease.

Dendritic cells (DCs) play an unsettled role in chronic obstructive pulmonary disease (COPD) pathogenesis. Two main blood subsets, myeloid (m) and plasmacytoid (p) DCs, have been identified in humans. Phenotype and frequency of circulating DC subsets were assessed by multi-parametric flow cytometry in 28 COPD patients and 30 healthy controls (15 never smokers and 15 smokers). Proportion and absolute number of pDCs were significantly reduced in COPD patients in comparison with never smokers (p<0.001 and p<0.003) along with a marked increase of the mDC/pDC ratio (p<0.001). Analysis of peripheral lymphocyte subsets showed that the naive/memory T cell ratio was significantly reduced in COPD patients in comparison with never smokers (p<0.001). Similar perturbations in the distribution of DCs and T cells also occurred in control smokers. This study is the first report of an imbalance of blood DCs in COPD. Influence of smoking and clinical relevance of these findings are discussed.

Meta-Immunological Profiling of Children With Type 1 Diabetes Identifies New Biomarkers to Monitor Disease Progression

Type 1 diabetes is characterized by autoimmune destruction of pancreatic β-cells in genetically susceptible individuals. Triggers of islet autoimmunity, time course, and the precise mechanisms responsible for the progressive β-cell failure are not completely understood. The recent escalation of obesity in affluent countries has been suggested to contribute to the increased incidence of type 1 diabetes. Understanding the link between metabolism and immune tolerance could lead to the identification of new markers for the monitoring of disease onset and progression. We studied several immune cell subsets and factors with high metabolic impact as markers associated with disease progression in high-risk subjects and type 1 diabetic patients at onset and at 12 and 24 months after diagnosis. A multiple correlation matrix among different parameters was evaluated statistically and assessed visually on two-dimensional graphs. Markers to predict residual β-cell function up to 1 year after diagnosis were identified in multivariate logistic regression models. The meta-immunological profile changed significantly over time in patients, and a specific signature that was associated with worsening disease was identified. A multivariate logistic regression model measuring age, BMI, fasting C-peptide, number of circulating CD3+CD16+CD56+ cells, and the percentage of CD1c+CD19−CD14−CD303− type 1 myeloid dendritic cells at disease onset had a significant predictive value. The identification of a specific meta-immunological profile associated with disease status may contribute to our understanding of the basis of diabetes progression.

Thymoma-associated immunodeficiency: a syndrome characterized by severe alterations in NK, T and B-cells and progressive increase in naïve CD8+ T Cells.

Thymomas are rare tumours that sustain T-lymphopoiesis and trigger a variety of autoimmune diseases and immunodeficiencies, including a fatal hypogammaglobulinemia, namely Goods Syndrome (GS). Due to its rarity, GS has been poorly investigated and immunological features, as well as pathogenetic mechanisms underlying this syndrome, are unclear. We studied 30 thymoma patients by performing an immunological assessment, including immunophenotype and analysis of T cell repertoire (TCR). Development of GS was characterized by a progressive decrease in B, CD4 T and NK lymphocytes. These alterations paired with accumulation of CD8+CD45RA+ T cells that showed a polyclonal repertoire without expansions of specific clonotypes. GS is defined as hypogammaglobulinemia with thymoma. Here, we show for the first time that this syndrome is characterized by a severe loss of CD4+, NK and B cells. Furthermore, the accumulation of CD8+CD45RA+ T lymphocytes parallels these changes; this accumulation may have a role in determining the disease and can be used to monitor clinical stages of immunodeficiency in thymoma.

Cutting Edge: Increased Autoimmunity Risk in Glycogen Storage Disease Type 1b Is Associated with a Reduced Engagement of Glycolysis in T Cells and an Impaired Regulatory T Cell Function

Glycogen storage disease type 1b (GSD-1b) is an autosomal-recessive disease caused by mutation of glucose-6–phosphate transporter and characterized by altered glycogen/glucose homeostasis. A higher frequency of autoimmune diseases has been observed in GSD-1b patients, but the molecular determinants leading to this phenomenon remain unknown. To address this question, we investigated the effect of glucose-6–phosphate transporter mutation on immune cell homeostasis and CD4+ T cell functions. In GSD-1b subjects, we found lymphopenia and a reduced capacity of T cells to engage glycolysis upon TCR stimulation. These phenomena associated with reduced expression of the FOXP3 transcription factor, lower suppressive function in peripheral CD4+CD25+FOXP3+ regulatory T cells, and an impaired capacity of CD4+CD25− conventional T cells to induce expression of FOXP3 after suboptimal TCR stimulation. These data unveil the metabolic determinant leading to an increased autoimmunity risk in GSD-1b patients.

CD8+ T-cell alveolitis in familial pulmonary alveolar microlithiasis

Pulmonary alveolar microlithiasis (PAM) is a rare diffuse lung disease characterised by the accumulation of calcium phosphate microliths within the alveoli. The causative mechanism of PAM has only recently been discovered, and involves a gene mutation of sodium phosphate co-transporter, which is expressed by alveolar epithelial cells. This mutation may have variable consequences on the clinical phenotype. However, pulmonary cell immune phenotyping in familial PAM has not previously been assessed. In the present article, the analysis of bronchoalveolar lavage fluid of two siblings with PAM diagnosis revealed a pattern of lymphocytic alveolitis with accumulation of CD8+ T-cells. The clonal complexity of this lymphocyte’s population was assayed by spectratyping, which showed an oligoclonal accumulation of T-cells with a restricted variable beta T-cell receptor (TCR) gene usage. TCR analysis in peripheral blood lymphocytes revealed no abnormal patterns of T-lymphocytes. In the pulmonary alveolar microlithiasis familial cases reported, CD8-mediated maladaptive immune response may have taken place in the bronchoalveolar compartment. The relationship between this immune dysregulation and genetic background in pulmonary alveolar microlithiasis warrants further investigation.