T. Feola*a (Dr), D. De Alcubierrea (Dr), G. Pulianib (Dr), F. Sciarraa (Dr), A. Cozzolinoa (Dr), ML. Appetecchiab (Prof), E. Sbardellaa (Dr), ML. Jaffrain-Reac (Prof), MA. Venneria (Prof), AM. Isidoria (Prof)

a Department of Experimental Medicine, Sapienza University of Rome, Rome, ITALY ; b Oncological Endocrinology Unit, IRCCS Regina Elena National Cancer Institute, Rome, ITALY ; c Neuroendocrinology, Neuromed Institute, IRCCS, Pozzilli, ITALY

* tiziana.feola@uniroma1.it

Introduction: The GH/IGF1 axis has long been supposed to play a role in immune modulation, mainly affecting lymphocytes and monocytes. However, little is known about the distribution and function of circulating immune cells in acromegaly. We designed a prospective case-control study in order to evaluate the peripheral blood mononuclear cells (PBMCs) subpopulations in acromegalic patients.

Material and Methods: 14 patients with acromegaly (6M, 8F), 10 with controlled and 4 with uncontrolled disease, were studied. All patients were on medical treatment with somatostatin analogs or pegvisomant, and 16 healthy sex-, age- and BMI- matched controls were enrolled. Anthropometric, metabolic, and hormonal parameters were recorded along with full quantification of PBMCs evaluated by flow cytometry. Data as expressed as median (interquartile range) and statistical analysis were performed with parametric and non-parametric tests, as appropriate.

Results: Compared with controls, acromegalic patients showed higher levels of glucose (p=0.001), HbA1c (p=0.026), and GH (p=0.019) and a higher prevalence of hypertension (p=0.046). Significant differences in monocytes number and subpopulations were observed, with a decreased total monocytes count (cells/μL) [128.0 (51.0-243.0) vs 339 (280.2-414.6), p<0.001], a lower percentage of classical monocytes, % [83.6 (79.1-88.0) vs 87.8 (84.9-91.3), p=0.023] and intermediate monocytes, % [2.4 (0.3-4.4) vs 7.3 (5.5-10.4) p<0.001] and higher percentage of non-classical monocytes, % [11.3 (10.4-14.3) vs 1.7 (1.0-3.3), p<0.001], as compared with controls. Acromegalic patients also showed a decreased total number of NK (cells/μL) [121.6 (62.0-261.3) vs 333.7 (253.4-485.4), p<0.001] with a lower percentage of NK CD56bright, % [3.44 (1.5-5.7) vs 7.8 (6.9-10.2), p=0.001] and a higher percentage of NK CD56dim, % [97.1 (93.5-97.8) vs 91.3 (88.2-92.8), p=0.003] than in controls. No differences in lymphocytes were found between the two groups.

Discussion: These preliminary results showed that acromegalic patients on medical treatment have a shift in monocyte subpopulations with a higher proportion of non-classical (anti-inflammatory) subset and a reduced total number of NK cells with an increase of the more naturally cytotoxic subset, supporting the role of GH/IGF1 axis in the modulation of the innate immunity.

The author has declared no conflict of interest.