Klinefelter syndrome, insulin resistance, metabolic syndrome, and diabetes: review of literature and clinical perspectives

Klinefelter syndrome (KS), the most frequent chromosomic abnormality in males, is associated with hypergonadotropic hypogonadism and an increased risk of cardiovascular diseases (CVD). The mechanisms involved in increasing risk of cardiovascular morbidity and mortality are not completely understood. Insulin resistance, metabolic syndrome, and type 2 diabetes are more frequently diagnosed in KS than in the general population; however, the contribution of hypogonadism to metabolic derangement is highly controversial. Whether this dangerous combination of risk factors fully explains the CVD burden of KS patients remains unclear. In addition, testosterone replacement therapy only exerts a marginal action on the CVD system. This review summaries the current understandings of the complex relationship between KS, metabolic syndrome and cardiovascular risk in order to plan future studies and improve current strategies to reduce mortality in this high-risk population. Since fat accumulation and distribution seem to play a relevant role in triggering metabolic abnormalities, an early diagnosis and a tailored intervention strategy with drugs aimed at targeting excessive visceral fat deposition appear necessary in patients with KS

DataSheet_1_cAMP-specific phosphodiesterase 8A and 8B isoforms are differentially expressed in human testis and Leydig cell tumor.pdf

Cyclic adenosine monophosphate/Protein kinase A (cAMP/PKA) signaling pathway is the master regulator of endocrine tissue function. The level, compartmentalization and amplitude of cAMP response are finely regulated by phosphodiesterases (PDEs). PDE8 is responsible of cAMP hydrolysis and its expression has been characterized in all steroidogenic cell types in rodents including adrenal and Leydig cells in rodents however scarce data are currently available in humans. Here we demonstrate that human Leydig cells express both PDE8A and PDE8B isoforms. Interestingly, we found that the expression of PDE8B but not of PDE8A is increased in transformed Leydig cells (Leydig cell tumors-LCTs) compared to non-tumoral cells. Immunofluorescence analyses further reveals that PDE8A is also highly expressed in specific spermatogenic stages. While the protein is not detected in spermatogonia it accumulates nearby the forming acrosome, in the trans-Golgi apparatus of spermatocytes and spermatids and it follows the fate of this organelle in the later stages translocating to the caudal part of the cell. Taken together our findings suggest that 1) a specific pool(s) of cAMP is/are regulated by PDE8A during spermiogenesis pointing out a possible new role of this PDE8 isoform in key events governing the differentiation and maturation of human sperm and 2) PDE8B can be involved in Leydig cell transformation.</p

Effect of SILD on STZ-diabetic kidney: modulation of macrophage infiltration.

<p>(A) Representative photomicrographs of H&E-stained kidneys (×200 magnification) on harvesting show normal structure in the CTRL and SILD, mild mesangial expansion and tubular damage in the STZ, and normal structure in the STZ+SILD group (bar represents 100 μm).(B) and (C) Glomerular and tubulointerstitial damage index scores are shown for each group. Data are expressed as mean ± SD. ^<b>**</b>P <0.01 STZ vs CTRL; ^<b>##</b>P <0.01 vs STZ (Student’s t-test).(D) Histograms indicate percentage of F4/80^<b>+</b> cells. Results are expressed as mean ± SD (n = 4 in each group) ^<b>**</b>P <0.01 STZ vs CTRL; ^<b>##</b>P <0.01 STZ+SILD vs STZ (Student’s t-test).(E) Immunophenotype of infiltrating macrophages in kidneys from representative CTRL, SILD, STZ and STZ+SILD mice, performed to assess expression of F4/80 and CD11b. Percentage of F4/80^<b>+</b> cells is augmented in STZ mice. One experiment representative of several independent experiments is shown.(F) Confocal analysis for F4/80 (green) and iNOS (red) shows abundant interstitial inflammatory macrophages (iNOS^<b>+</b>) in renal sections from STZ mice, that were significantly decreased in STZ+SILD mice. (G) Relative F4/80^<b>+</b> and iNOS^<b>+</b> area quantification. Each dot represents one slide in different kidney groups.(H) Quantification of VCAM-1 and COX-2 to GAPDH expression detected by Western blotting reveals vascular inflammation in kidneys from STZ mice and less damage in kidneys from STZ+SILD mice.</p

Metabolic characteristics and survival of treated mice.

<p>(A) Schematic representation of the experimental design. (B) Plasma glucose levels in diabetic (STZ and STZ+SILD) vs. non-diabetic (CTRL) mice. Results are expressed as mean ± SD (n = 7 in each group). (C) Changes in water consumption in STZ and STZ+SILD vs. CTRL mice. Results are expressed as mean ± SD (n = 4 in each group). (D) Changes in food consumption index in STZ and STZ+SILD vs. CTRL mice. Results are expressed as mean ± SD (n = 4 in each group). (E) Kaplan-Meier survival curve of CTRL, SILD, STZ and STZ+SILD mice.</p

Mice group characteristics after 3-week sildenafil treatment.

<p>Values are presented as mean ± SD, ^aP <0.05 and ^aaP <0.01, STZ treated versus normal and ^bP<0.05, STZ+SILD treated versus STZ.</p><p>Mice group characteristics after 3-week sildenafil treatment.</p

Effect of SILD on cardiac hypertrophy and macrophage infiltration.

<p>(A) Representative photomicrographs of H&E-stained heart from CTRL, SILD, STZ and STZ+SILD mice on harvesting (bar represents 100μm).(B) Histogram shows heart cross-sectional area. Results are expressed as mean ± SD (n = 4 in each group). ^*P <0.05 STZ vs CTRL; ^#P <0.05 STZ+SILD vs STZ (Student’s t-test).(C) Histogram shows mRNA quantitative analysis ANP. Results are expressed as mean ± SD (n = 3 in each group). ^*P <0.05 STZ vs CTRL; ^##P <0.01 STZ+SILD vs STZ (Student’s t-test).(D) β-MHC and GAPDH expression detected by Western blotting. Histogram shows activation of hypertrophic protein in STZ mice that was reduced in STZ+SILD mice. Results are expressed as mean ± SD (n = 3 in each group) ^##P <0.01 STZ+SILD vs STZ (Student’s t-test).(E) Histogram illustrates percentage of infiltrating F4/80⁺ cells in the heart from CTRL, SILD, STZ and STZ+SILD mice. Results are expressed as mean ± SD (n = 4 in each group). ^*P <0.05 STZ vs CTRL; ^#P <0.0 STZ+SILD vs STZ (Student’s t-test).(F) Histograms indicates percentage of F4/80⁺TIE2⁺ cells. Expression of F4/80⁺TIE2⁺ cells was decreased in STZ compared with CTRL mice and increased in STZ+SILD compared with STZ mice. Results are expressed as mean ± SD (n = 4 in each group), ^*P <0.05 STZ vs CTRL; ^##P <0.01 STZ+SILD vs STZ (Student’s t-test).(G) iNOS and COX-2 expression detected by Western blotting. Histogram shows induction of inflammatory proteins in STZ mice that was reduced in STZ+SILD mice. Results are expressed as mean ± SD (n = 3 in each group). ^**P <0.01 STZ vs CTRL, ^##P <0.01 STZ+SILD vs STZ (Student’s t-test).</p

SILD increases renal expression of TEMs pro-angiogenic macrophages.

<p>(A) Representative of at least 4 flow cytometry analyses of macrophage infiltration in kidney from CTRL, SILD, STZ and STZ+SILD mice, showing TIE2 expression in a subset of monocytes (filled line in the histogram plots).(B) Histograms indicate percentage of TIE2^<b>+</b> in the F4/80^<b>+</b> macrophages population. Expression of F4/80^<b>+</b>TIE2^<b>+</b> cells decreased in STZ compared to CTRL mice and increased in the STZ+SILD compared to STZ mice. Results are expressed as mean ± SD (n = 4 in each group); ^<b>*</b>P <0.01 STZ vs CTRL; ^<b>##</b>P <0.01 STZ+SILD vs STZ (Student’s t-test).(C) Confocal analysis for kidney TEMs from representative CTRL, SILD, STZ and STZ+SILD mice, performed for TIE2 (green) and MRC1 (blu). TIE2^<b>+</b>MRC1^<b>+</b> macrophages were lower in STZ than in CTRL and higher in SILD and STZ+SILD groups (bar represents 30μm).</p

SILD inhibits high-glucose-induced adhesion via TIE2 receptor.

<p>(A) THP1 cell adhesion to HUVEC. Note that there are more adherent monocyte cells in high-glucose than in normal condition medium. SILD inhibits high-glucose-induced adhesion and co-treatment with TIE2-Fc cancelled this effect (n = 3/treatment group). (B) Quantification of monocyte adhesion to HUVEC. Histogram shows number of adherent cells per field in different experimental groups (n = 3/group). Results are shown as mean ± SD (n = 5 in each group). ^<b>***</b> P <0.001. ^<b>**</b> P <0.01 (Student’s t-test).(C) VCAM-1, NF-kB and GAPDH expression detected by Western blotting reveals that SILD inhibits vascular inflammation induced by high glucose treated HUVEC, while co-treatment TIE2-Fc cancelled this effect in VCAM-1.</p

Multiple linear regression models concerning thyroid structure and function

Multiple linear regression models to ascertain the potential confounding role of anthropometric variables in adult Klinefelter syndrome patients on each of the thyroid outcomes of interest, with gonadal status as the independent variable and the anthropometric variables significantly different between gonadal status groups acting as covariates, and fT4 levels, the fT3/fT4 ratio, echogenicity and homogeneity as dependent variables </p