Paracrine interactions within the pituitary gland

Unveiling Mesenchymal Stem Cells' Regenerative Potential in Clinical Applications: Insights in miRNA and lncRNA Implications

It is now widely recognized that mesenchymal stem cells (MSCs) possess the capacity to differentiate into a wide array of cell types. Numerous studies have identified the role of lncRNA in the regulation of MSC differentiation. It is important to elucidate the role and interplay of microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) in the regulation of signalling pathways that govern MSC function. Furthermore, miRNAs and lncRNAs are important clinical for innovative strategies aimed at addressing a wide spectrum of existing and emerging disease. Hence it is important to consider their impact on MSC function and differentiation. Examining the data available in public databases, we have collected the literature containing the latest discoveries pertaining to human stem cells and their potential in both fundamental research and clinical applications. Furthermore, we have compiled completed clinical studies that revolve around the application of MSCs, shedding light on the opportunities presented by harnessing the regulatory potential of miRNAs and lncRNAs. This exploration of the therapeutic possibilities offered by miRNAs and lncRNAs within MSCs unveils exciting prospects for the development of precision therapies and personalized treatment approaches. Ultimately, these advancements promise to augment the efficacy of regenerative strategies and produce positive outcomes for patients. As research in this field continues to evolve, it is imperative to explore and exploit the vast potential of miRNAs and lncRNAs as therapeutic agents. The findings provide a solid basis for ongoing investigations, fuelling the quest to fully unlock the regenerative potential of MSCs.

Perioperative fluctuation and overall evaluation of adenohypophyseal hormone secretion in patients with nonfunctioning pituitary adenoma

OBJECTIVE

Perioperative adenohypophyseal hormone assessment can improve therapeutic strategies and be used to evaluate the prognosis of pituitary adenomas. An individual hormone level does not entirely reflect the pituitary gland. Thus, this study aimed to analyze perioperative hormonal changes and propose a normalized method to facilitate overall assessment of the adenohypophysis.

METHODS

The authors retrospectively analyzed 89 male patients with nonfunctioning pituitary adenoma (NFPA) who underwent transsphenoidal surgery. Preoperative clinical data, imaging data, and perioperative hormone levels of the anterior pituitary gland were evaluated. Hormone values were rescaled using minimum-maximum normalization. The sum of the normalized hormone levels was defined as the total hormonal rate (THR).

RESULTS

Preoperative findings indicated correlations among different adenohypophyseal hormones. Luteinizing hormone (p = 0.62) and adrenocorticotropic hormone (p = 0.89) showed no significant changes after surgery, but growth hormone levels increased (p < 0.001). On the contrary, the levels of thyroid-stimulating hormone (p < 0.001), follicle-stimulating hormone (p = 0.02), and prolactin (p < 0.001) decreased. THR indicated a significant postoperative reduction in adenohypophyseal function (p = 0.04). Patients with postoperative hypopituitarism had significantly lower THR than those without (p = 0.003), with an area under the curve of 0.66. For NFPAs that presented with normal preoperative hormone levels, THR was a good clinical predictor of immediate postoperative hypopituitarism, with an area under the curve of 0.74.

CONCLUSIONS

The normalized synthesis index of hormones is a novel and clinically valuable method used to reflect adenohypophyseal secretion. Compared with individual hormones, these results indicated that THR can facilitate the analysis of general hormone levels despite various fluctuations in adenohypophyseal hormones. THR may also contribute to the effective prediction of short-term surgery-induced hypopituitarism.

Morphometric analysis of somatotropic and folliculostellate cells of human anterior pituitary during ageing

Introduction/Objective. In this study, we have pointed out the immunohistomorphometric characteristics of somatotropic (GH) and folliculo-stellate (FS) cells of the human pituitary gland during ageing. Methods. On histological sections of the pituitary gland of 14 male cadavers of different ages, the GH and FS cells were immunohistochemically labeled with corresponding antibodies, monoclonal anti-GH antibody and polyclonal anti-S100 antibody, respectively. Immunopositive GH- and FS-cells were further morphometrically analyzed using ImageJ software. Results. The obtained results of morphometric analysis showed that the surface area of GH cells increased significantly with age. In these cells, the nuclear-cytoplasmic ratio gradually decreased and became significantly higher after the age of 70 years. The volume density of GH cells has not changed during ageing, while in FS cells this parameter significantly increased in the cases older than 70 years. The nuclear-cytoplasmic ratio of GH cells is negatively correlated with the volume density of FS cells. Conclusions. Based on the obtained results, we concluded that hypertrophy of GH and FS cells occurs in men with ageing and that correlation between the morphometric parameters of these two cell types indicates their mutual interaction.

Upregulated tumor necrosis factor-α transcriptome and proteome in adipose tissue-derived mesenchymal stem cells from pigs with metabolic syndrome

INTRODUCTION

Mesenchymal stem cells (MSCs) have endogenous reparative properties, and may constitute an exogenous therapeutic intervention in patients with chronic kidney disease. The microenvironment of metabolic syndrome (MetS) induces fat inflammation, with abundant expression of tumor necrosis factor (TNF)-α. MetS may also alter the content of adipose tissue-derived MSCs, and we hypothesized that the inflammatory profile of MetS manifests via upregulating MSC mRNAs and proteins of the TNF-α pathway.

METHODS

Domestic pigs were fed a 16-week Lean or MetS diet (n = 4 each). MSCs were harvested from abdominal subcutaneous fat, and their extracellular vesicles (EVs) isolated. Expression profiles of mRNAs and proteins in MSCs and EVs were obtained by high-throughput sequencing and proteomics. Nuclear translocation of the pro-inflammatory transcription factor (NF)-kB was evaluated in MSC and in pig renal tubular cells (TEC) co-incubated with EVs.

RESULTS

We found 13 mRNAs and 4 proteins in the TNF-α pathway upregulated in MetS- vs. Lean-MSCs (fold-change > 1.4, p < 0.05), mostly via TNF-α receptor-1 (TNF-R1) signaling. Three mRNAs were upregulated in MetS-EVs. MetS-MSCs, as well as TECs co-incubated with MetS-EVs, showed increased nuclear translocation of NF-kB. Using qPCR, JUNB, MAP2K7 and TRAF2 genes followed the same direction of RNA-sequencing findings.

CONCLUSIONS

MetS upregulates the TNF-α transcriptome and proteome in swine adipose tissue-derived MSCs, which are partly transmitted to their EV progeny, and are associated with activation of NF-kB in target cells. Hence, the MetS milieu may affect the profile of endogenous MSCs and their paracrine vectors and limit their use as an exogenous regenerative therapy. Anti-inflammatory strategies targeting the TNF-α pathway might be a novel strategy to restore MSC phenotype, and in turn function.

Morphometric analysis of the folliculostellate cells and luteinizing hormone gonadotropic cells of the anterior pituitary of the men during the aging process

The aim of this research was to quantify the changes in the morphology and density of the anterior pituitary folliculostellate (FS) and luteinizing hormone (LH) cells. Material was tissue of the pituitary gland of the 14 male cadavers. Tissue slices were immunohistochemically stained with monoclonal anti-LH antibody and polyclonal anti-S100 antibody for the detection of LH and FS cells, respectively. Digital images of the stained slices were afterwards morphometrically analyzed by ImageJ. Results of the morphometric analysis showed significant increase of the FS cells volume density in cases older than 70 years. Volume density of the LH cells did not significantly change, whereas their area significantly increased with age. Nucleocytoplasmic ratio of the LH cells gradually decreased and became significant after the age of 70. Finally, volume density of the FS cell significantly correlated with LH cells area and nucleocytoplasmic ratio. From all above cited, we concluded that in men, density and size of the FS cells increase with age. Long-term hypertrophy of the LH cells results in their functional decline after the age of 70. Strong correlation between FS cells and LH cells morphometric parameters might point to age-related interaction between these two cell groups.

Secretagogue induction of GH release in QNR/D cells: prevention of cell death

Retinal ganglion cells (RGCs) in the chick embryonic neural retina are extrapituitary sites of growth hormone (GH) synthesis and release. The regulation of GH secretion by these cells is largely unknown, although we recently discovered several of the hypothalamic releasing factors involved in pituitary GH regulation (including GH-releasing hormone (GHRH) and thyrotropin releasing hormone, TRH) to be present in the cytoplasm of immortalized quail RGCs (QNR/D cells). QNR/D cells may therefore provide an experimental model for studies on GH regulation in the chick neural retina. The possibility that GHRH and TRH might stimulate GH secretion in QNR/D cells was therefore investigated. Both peptides acutely depleted the GH content of the QNR/D cells, as demonstrated by immunocytochemistry and ELISA, whilst increasing the GH content in incubation media. Both peptides also increased the immunochemical and ELISA content of the QNR/D cells and the content of GH in the incubation media after long-term incubation. Cell survival, determined by metabolic activity of the QNR/D cells and by TUNEL-labeling, was reduced when the endogenous GH content was reduced by GH immunoneutralization, even in the presence of exogenous GHRH or TRH. Cell survival was also reduced when endogenous GHRH was blocked by GHRH immunoneutralization, although the immunoneutralization of endogenous TRH did not affect QNR/D cell survival. In summary, these results demonstrate secretagogue actions of exogenous GHRH and TRH on the secretion of GH from QNR/D cells. They also suggest that endogenous GHRH, but not endogenous TRH, prevents cell death by increasing endogenous GH secretion in QNR/D cells.

Effect of the photoperiod and administration of melatonin on folliculostellate cells of the pituitary pars distalis of adult male viscacha (Lagostomus maximus maximus)

Numerous reports have shown the effect of photoperiod and melatonin administration on the different hormone secreting cell types in the pituitary pars distalis. The viscacha (Lagostomus maximus maximus) is a rodent with photoperiod-dependent seasonal reproduction. The aim of this study was to examine the effect of photoperiod seasonal variations and melatonin administration on the folliculostellate cells in pituitary pars distalis of viscacha. Immunohistochemistry and image analysis were used to measure the percentage of S-100-positive area (total, cellular and colloidal) and the number of folliculostellate cells. The S-100 protein was immunolocalized at intracellular (folliculostellate cells) and extracellular (follicular colloid) levels. The morphometric parameters analyzed exhibited seasonal variations with highest values in the summer (long photoperiod) and lowest values in the winter (short photoperiod). The administration of melatonin caused a significant decrease of immunostaining. Results suggest that the natural photoperiod might be the most important environmental signal causing the decrease in folliculostellate cells immunostaining observed in the winter. These findings agree with seasonal changes previously reported in endocrine cells and suggest that folliculostellate cells may be involved in the paracrine regulation of the secretory activity of pituitary pars distalis through S-100 protein production.

Mesenchymal stromal cells. Biology of adult mesenchymal stem cells: regulation of niche, self-renewal and differentiation

Recent advances in understanding the cellular and molecular signaling pathways and global transcriptional regulators of adult mesenchymal stem cells have provided new insights into their biology and potential clinical applications, particularly for tissue repair and regeneration. This review focuses on these advances, specifically in the context of self-renewal and regulation of lineage-specific differentiation of mesenchymal stem cells. In addition we review recent research on the concept of stem cell niche, and its relevance to adult mesenchymal stem cells.

IVIG-pools: regulatory gifts--transiting from harmony toward harmonious immunoglobulins: why? and why not?

Based on 'initial conditions' which depend on each donors' exposure to a unique environment, a pooled intravenous immunoglobulin (IVIG) product transfers its immunoglobulin molecule repertoire, unchanged, to the altered host. The relay function of the cell-bound receptors, especially that of the inhibitory Fc(gamma)RIIB, may then allow sufficient amplification to make regulatory activity possible. To the clinician, IVIG may be considered a tool to promote reversal of the dysregulation causing autoimmune disease. Generically, IVIG may be seen as a promoter allowing a progression from harm by an inflammatory/fibrotic reaction, then down-regulating toward restitutio ad integrum. By modifying natural processes, IVIG may play minor roles in promoting defense against spontaneous bleeding and, perhaps, stimulating remyelination. The wide spectrum of IVIG specificities, by reflecting evolutionary epitope selection, may not further destabilize cell/molecule disarray in the affected host. Benefit to the patient by IVIG treatment cannot be predicted nor can potentially severe or even fatal accidents entirely be excluded. Important aspects of IVIG treatment still await clarification including dosage, timing and the isotype form. In the foreseeable future it does not seem that biotechnological advances will match the physiologic harmony of IVIG, leaving antibody characteristics aside.

Prolactin: structure, function, and regulation of secretion

Prolactin is a protein hormone of the anterior pituitary gland that was originally named for its ability to promote lactation in response to the suckling stimulus of hungry young mammals. We now know that prolactin is not as simple as originally described. Indeed, chemically, prolactin appears in a multiplicity of posttranslational forms ranging from size variants to chemical modifications such as phosphorylation or glycosylation. It is not only synthesized in the pituitary gland, as originally described, but also within the central nervous system, the immune system, the uterus and its associated tissues of conception, and even the mammary gland itself. Moreover, its biological actions are not limited solely to reproduction because it has been shown to control a variety of behaviors and even play a role in homeostasis. Prolactin-releasing stimuli not only include the nursing stimulus, but light, audition, olfaction, and stress can serve a stimulatory role. Finally, although it is well known that dopamine of hypothalamic origin provides inhibitory control over the secretion of prolactin, other factors within the brain, pituitary gland, and peripheral organs have been shown to inhibit or stimulate prolactin secretion as well. It is the purpose of this review to provide a comprehensive survey of our current understanding of prolactin's function and its regulation and to expose some of the controversies still existing.