Cellular and Nerve Fibre Catecholaminergic Thymic Network: Steroid Hormone Dependent Activity

The thymus plays a critical role in establishing and maintaining the peripheral T-cell pool. It does so by providing a microenvironment within which T-cell precursors differentiate and undergo selection processes to create a functional population of major histocompatibility complex-restricted, self-tolerant T cells. These cells are central to adaptive immunity. Thymic T-cell development is influenced by locally produced soluble factors and cell-to-cell interactions, as well as by sympathetic noradrenergic and endocrine system signalling. Thymic lymphoid and non-lymphoid cells have been shown not only to express beta- and alpha(1)-adrenoceptors (ARs), but also to synthesize catecholamines (CAs). Thus, it is suggested that CAs influence T-cell development via both neurocrine/endocrine and autocrine/paracrine action, and that they serve as immunotransmitters between thymocytes and nerves. CAs acting at multiple sites along the thymocyte developmental route affect T-cell generation not only numerically, but also qualitatively. Thymic CA level and synthesis, as well as AR expression exhibit sex steroid-mediated sexual dimorphism. Moreover, the influence of CAs on T-cell development exhibits glucocorticoid-dependent plasticity. This review summarizes recent findings in this field and our current understanding of complex and multifaceted neuroendocrine-immune communications at thymic level

Role of ovarian hormones in thymic involution in rats

Timus je primarni limfoidni organ koji obezbeđuje mikrosredinu neophodnu za diferencijaciju/sazrevanje T-limfocita. Tokom ontogeneze, ovaj organ trpi značajne strukturne i funkcionalne promene koje se zbirno označavaju kao involucija timusa, i manifestuju se kao smanjena efikasnosti timopoeze i posledično, smanjen izlazak novoformiranih T-limfocita na periferiju. Involucija timusa je kod glodara najizraženija u periodu sticanja polne zrelosti. Veliki broj literaturnih podataka ukazuje na to da hormoni hipotalamo-hipofizo-gonadne (H-H-G) osovine, pre svega hormoni gonada, utiču na razvoj i involuciju timusa. Međutim, uprkos brojnim istraživanjima u proteklim decenijama, uloga hormona jajnika u inicijaciji i održavanju/progresiji involucije timusa nije do kraja rasvetljena. Cilj ove doktorske disertacije je bio da se ispita uloga hormona jajnika u inicijaciji i održavanju/progresiji involucije timusa. U tom cilju ispitivan je uticaj jednokratnog davanja testosterona u kritičnom neonatalnom uzrastu, koji dovodi do odlaganja sazrevanja H-H-G osovine i promena u obrascu sekrecije hormona jajnika kod adultnih životinja (neonatalna androgenizacija) i uklanjanja jajnika ženkama pacova u uzrastu od 10 meseci, kada su involutivne promene timusa jasno izražene, na građu timusa i timopoezu u ranom adultnom uzrastu; odnosno u uzrastu od 11 meseci. Posebno je ispitivan, mogući, indirektan uticaj promena u sekreciji hormona jajnika na aktivnost timusnog kateholaminergičkog regulatornog sistema. Neonatalna androgenizacija, delujući na različite stadijume diferencijacije/sazrevanja T-ćelija, od ulaska/diferencijacije progenitorskih ćelija do linijskog usmeravanja timocita, povećala je efikasnost timopoeze (na osnovu većeg broja svežih timusnih emigranata u perifernoj krvi i slezini), uključujući, najverovatnije, i povećano stvaranje ćelija regulatornog fenotipa (CD4+CD25+FoxP3+ i CD161+TCRαβ+ ćelije). Pored toga, kod ovih životinja je uočeno favorizovano stvaranje ćelija CD4-CD8+TCRαβ++ fenotipa (fenotipska defeminizacija/maskulinizacija procesa timopoeze). Uprkos povećanoj efikasnosti timopoeze, nepromenjena relativna zastupljenost timusnih epitelnih ćelija (TEC) kao i nivo iRNK za IL-6, a smanjen nivo iRNK za IL-7 u tkivu timusa, ukazuju, da je kod neonatalno androgenizovanih životinja, u uzrastu od 3 meseca, najverovatnije, došlo do pokretanja mehanizama negativne povratne sprege, koji ograničavaju ekspanziju TEC i timopoezu. Ovarijektomija u uzrastu od 10 meseci, nakon 30. dana, imala je za posledicu povećanje relativne zastupljenosti TEC i efikasnosti timopoeze (uključujući i povećano stvaranje ćelija regulatornog fenotipa), što se manifestovalo povećanim brojem svežih timusnih emigranata CD4+ i CD8+ fenotipa u perifernoj krvi i slezini. Međutim, uprkos regeneraciji epitelne komponente timusa i povećanoj efikasnosti timopoeze, smanjen nivo iRNK za IL-6 i IL-7 u tkivu timusa ovarijektomisani životinja sugeriše da je kod ovih životinja došlo do aktivacije intratimusnih mehanizama negativne povratne sprege koji ograničava ekspanziju TEC koje sintetišu IL-6 i efikasnost timopoeze. U zaključku, nalazi dobijeni u ovoj disertaciji ukazuju da neonatalna androgenizacija menja kinetiku postnatalnog razvoja timusa i polno specifičan obrazac diferencijacije/sazrevanja timocita i odlaže, ali vrlo verovatno ne sprečava involuciju timusa, dok uklanjanje hormona jajnika u uzrastu kada su involutivne promene timusa uznapredovale dovodi do delimične reverzije ovih promena i efikasnije timopoeze, koji su, najverovatnije, vremenski ograničenog trajanja. Pored toga, pokazano je da se uticaj hormona jajnika na ove procese odvija i indirektno, menjanjem efikasnosti modulatornog delovanja noradrenalina na timopoezu.The thymus is a primary lymphoid organ that provides the microenvironment necessary for the differentiation/maturation of T-lymphocytes. During ontogeny, thymus undergoes significant structural and functional changes leading to reduced efficiency of thymopoiesis and, consequently, reduced output of newly generated Tlymphocytes. These changes are collectively referred to as thymic involution. The most profound thymic changes in rodents, occur around puberty. There is an accumulating body of evidence indicating that hormones of the hypothalamic-pituitary-gonadal (H-PG) axis, particularly gonadal hormones, influence thymic development and involution. However, despite extensive research in the past decades, the role of ovarian hormones in the initiation and maintenance/progression of thymic involution is not fully understood. Bearing all aforementioned in mind, this dissertation was aimed to elucidate the role of ovarian hormones in initiation and maintenance/progression of thymic involution. To this end the effects of single injection of testosterone in critical postnatal period, which postpones H-P-G axis maturation and affects the gender-specific pattern of gonadal hormone secretion in adult animals (neonatal androgenization), and ovarian hormone removal in rats with advanced thymic involutive changes (10-month-old), on thymic structure and function, were examined in 3-month-old and 11-month-old female rats, respectively. In addition, the putative indirect, catecholamine-mediated effects of the neonatal androgenization and ovariectomy on thymopoiesis were explored. Neonatal androgenization, affecting distinct stages of thymocyte differentiation/maturation (from progenitor cell entry and differentiation to thymocyte lineage commitment), increased the efficiency of thymopoiesis and consequently thymic output (as evidenced by the increased number of recent thymic emigrants in peripheral blood and spleen), including, most likely, increased output of the cells with regulatory phenotype (CD4+CD25+FoxP3+ and CD161+TCRαβ+ cells). In addition, neonatal treatment with testosterone skewed thymocyte lineage commitment towards CD4-CD8+TCRαβ++ cells (phenotypic defeminization/masculinization of thymopoiesis). Despite the increased efficiency of thymopoiesis, unaltered relative abundance of thymic epithelial cells (TEC) and the thymic level of IL-6 mRNA, and reduced thymic level of IL-7 mRNA, indicated, most likely, activation of intrathymic negative feedback mechanisms limiting TEC proliferation and thymopoiesis in 3- month-old neonatally androgenized rats. Ovariectomy at the age of 10 months led to the expansion of TECs and greater efficiency of thymopoiesis (including generation of cells with regulatory phenotype), increasing the number of both CD4+ and CD8+ recent thymic emigrants in peripheral blood and spleen of 11-month-old rats, compared with age-matched controls. However, despite the regeneration of the thymic epithelial component and increased efficiency of thymopoiesis, reduced thymic levels of mRNA for IL-6 and IL-7 in ovariectomized rats indicated activation of intrathymic negative feedback mechanisms limiting the expansion of IL-6-synthesizing TECs and thymopoietic efficiency in these animals. In conclusion, the data obtained in this dissertation indicate that neonatal androgenization alters the kinetics of postnatal thymic development and sex-specific pattern of thymocyte differentiation/maturation and postpones thymic involution, but, most likely, does not prevent it completely. The removal of ovarian hormones in female rats with advanced thymic involutive changes leads to partial reversion of these changes, and an increase in thymopoietic efficiency of, most likely, limited duration. In addition, these data indicate that ovarian hormones might affect thymic development/involution not only directly, but also indirectly by diminishing the efficiency of noradrenaline-mediated modulation of thymopoiesis

Immunoreactive neuropeptides in the cells of human thymus

The study was designed to explore the expression of different neuropeptides, viz. vasoactive intestinal peptide (VIP), calcitonin gene related peptide (CGRP), substance P (SP), bombesin and motilin in the cells of fetal and adult human thymus. Immunohistochemical staining revealed that cortical and medullary thymocytes were labeled by all antibodies, except those specific for motilin. Immunoreactive VIP and SP were observed in the solitary epithelial cells located in the subcapsular/subtrabecular cortex, at the corticomedullary junction and in the medulla. The cells within the subcapsular/subtrabecular monolayer, rare solitary cells in the deep cortex and epithelial cell network in the medulla, were labeled with antibodies to CGRP and bombesin. Hassall's corpuscles were labeled with all antibodies except that specific for SP. The obtained data obtained testify to the expression of different neuropeptides in human thymic lymphoid and non-lymphoid cells and suggest a role for neuroendocrine hormone-mediated mechanisms in the regulation of thymic homeostasis in humans

The assessment of genetic potential in performance tested gilts by means of selection indexes method

The objective of this research paper was to make an assessment of breeding value of performance tested gilts of Swedish Landrace and F-1 crossbreds of Swedish Landrace and Great Yorkshire by the method of selection index. The traits on whose basis the breeding value was estimated were: daily liveweight gain, average backfat thickness measured at two sites and carcass meat percentage. These traits were corrected for body mass of 100kg by the method of base indexes and the following average values were determined: corrected daily liveweight gain (KZDP) 408.93g/day, corrected average backfat thickness measured at two sites (KSL) 9.77mm and corrected carcass meat percentage (KPM) 61.08%. Studying the effect of genotype, year and birth season of gilts a statistically significant variation (P>0.05) of these traits provoked by the mentioned factors was not determined while the gilts sire statistically highly significantly (P lt 0.001) influenced all studied traits. Heritability coefficients were: h(2)= 0.255 for KZDP, h(2)= 0.356 for KSL and h(2)= 0.349 for KPM. The four selection index equations were constructed among which as the most optimal was chosen the one which includes all three traits (KZDP, KSL and KPM) and whose coefficient of the correlation of selection index and aggregate genotype was r(IAG) = 0.594

Peripubertetna ovarijektomija obezbeđuje dugotrajno odlaganje starenjem uslovljenog smanjenja celularnosti timusa i produkcije T limfocita

The present study was undertaken to reassess the recently challenged role of ovarian hormones in age-associated thymic involution. For this purpose, in eleven-month-old peripubertally ovariectomized (Ox) rats we analyzed: i) thymic weight and cellularity, ii) size of CD4+CD8+ double-positive (DP) thymocyte population, which is believed to correlate to the thymic capacity to export mature T cells, iii) number of recent thymic emigrants (RTEs), and iv) number of peripheral blood CD4+ and CD8+ lymphocytes. It was found that both thymic weight and cellularity were greater in Ox than in control rats. In addition, in Ox rats the numbers of DP thymocytes and both CD4+ and CD8+ RTEs, were significantly greater than in controls, indicating a more efficient generation of T cells in these rats. Furthermore, these findings, coupled with data indicating that the number of neither CD4+ nor CD8+ peripheral blood lymphocytes was affected by ovariectomy, most likely, suggest a reduced homeostatic proliferation of memory cells in Ox rats, i.e. broadening of TCR peripheral repertoire without changes in the overall number of T cells leading to a more efficient response to newly encountered antigens. The results indicate that the ovarian steroid deprivation from early peripubertal period leads to a long lasting postponement/alleviation of age-associated decline in T-cell mediated immune response.Ova istraživanja su preduzeta sa ciljem da se preispita uloga gonadnih hormona u involuciji timusa, koja je nedavno dovedena u pitanje. U tom cilju je kod 11 meseci starih ženki pacova, koje su ovarijektomisane (Ox) u peripubertetnom uzrastu, analizirana: i) težina i celularnost timusa, ii) broj CD4+CD8+ dvostruko pozitivnih (DP) timocita, za koji se smatra da odražavaju sposobnost organa da generiše zrele T limfocite, iii) broj neposrednih emigranata iz timusa (RTE) i iv) ukupan broj CD4+ i CD8+ limfocita u perifernoj krvi. Dokazano je da su težina i celularnost timusa bile značajno veće u Ox životinja. Kod ovih životinja je nađen i povećan broj DP timocita, kao i CD4+ i CD8+ RTE, što ukazuje na efikasniju produkciju T ćelija u njihovom timusu. Ovaj nalaz, u kontekstu nepromenjenog broja CD4+ i CD8+ ćelija u perifernoj krvi, takođe sugeriše smanjenu homeostatsku proliferaciju memorijskih ćelija, odnosno ukazuje na kvalitativne promene u perifernom T ćelijskom repertoaru (koje obezbeđuju efikasniji odgovor na nove antigene) bez kvantitativnih promena. U celini, rezultati ukazuju da u odsustvu hormona ovarijuma počevši od ranog peripubertetnog uzrasta dolazi do značajnog odlaganja/ublažavanja involucije timusa i posledičnih promena na periferiji

Environmental modeling of interaction variance for grain yield of medium early maturity maize hybrids

The phenomenon of genotype by environment interaction (GEI) represents permanent interest for breeders, geneticists and biometricians with its practical and theoretical aspects. We investigated GEI for grain yield of medium early maturity maize (Zea mays L.) hybrids from the official variety trial network by the Department of Protection and Recognition of Varieties of the Republic of Serbia that includes experimental maize hybrids on eight sites over two years. Environmental variables explained 77.6% and 60.7% of the GEI variation for two consecutive years, respectively. Factorial regression combined with stepwise procedure revealed the model which includes variables precipitation in July (pr7), minimum temperature in May (mnt5), maximum temperature in May (mxt5) and insolation hours in April (sh4), in 2004, and environmental index (EI) and average temperature in September (mt9) in 2005, to be the most explanatory models in the region of Vojvodina (Serbia) in two consecutive years. These results provide a base for further research in GEI and stability analysis, and are a useful tool in characterizing the sub-regions of maize growing area and extending the existing results to new sites

Peripubertal orchidectomy transitorily affects age-associated thymic involution in rats

The role of gonadal hormones in induction and, particularly, maintenance/ progression of rat thymic involution, which normally starts around puberty, was reassessed by examining the effects of peripubertal orchidectomy on thymic weight and morphometric parameters at different times up to the age of 10 months. Up to 6 months post-castration both thymic weight and cellularity in orchidectomized ( Cx) rats were greater than in age-matched control rats, sham Cx ( Sx). The increase in thymic cellularity reflected an increase in thymocyte proliferation rate ( the proportion of proliferating cells was 18.6 +/- 0.7% in 2-month-old Cx ( N = 5) vs 13.4 +/- 0.3% ( N = 5) in age-matched Sx rats) followed by reduced sensitivity to apoptotic signals ( apoptotic thymocytes were 9.8 +/- 0.9% in 2-month-old Cx ( N = 5) vs 15.5 +/- 0.3% ( N = 5) age-matched Sx rats). However, 9 months post-orchidectomy, neither thymic weight and cellularity nor any of the morphometric parameters analyzed differed between Cx and control rats. The reduction of thymic cellularity in Cx rats to control values may be related to increased sensitivity of their thymocytes to apoptotic signals in culture ( 72.6 +/- 1.2% in 10-month-old vs 9.8 +/- 0.9% in 2-month-old Cx rats) followed by reduced responsiveness to proliferative stimuli ( 14.1 +/- 0.2% in 10-month-old vs 18.6 +/- 0.7% in 2-month-old Cx rats). Thus, the study indicates that the effects of peripubertal orchidectomy on thymic weight and cellularity, as well as on the main morphometric indices, are long-lasting but not permanent, i.e., that removal of the testes can only postpone but not prevent age-related organ atrophy and consequently functional deterioration of the immune system

Cystatins, cysteine peptidase inhibitors, as regulators of immune cell cytotoxicity

Cystatins comprise a superfamily of evolutionarily related proteins, present in all living organisms, from protozoa to mammals. They act as inhibitors of cysteine peptidases although they can also function independently of their inhibitory function. Cysteine cathepsins are implicated in various physiological and pathological processes. In the immune response they are involved in antigen processing and presentation, the cytotoxicity of natural killer (NK) cells and cytotoxic T lymphocytes (CTL), migration and adhesion of immune cells, cytokine and growth factor regulation and toll-like receptor signalling. Cystatins are probably involved in the regulation of all these processes; importantly, cystatin F has a crucial role in the regulation of immune cell cytotoxicity. NK cells and CTLs exploit the granzyme/perforin pathway for target cell killing, with perforin and granzymes as crucial effector molecules. Granzymes are synthesized as inactive pro-granzymes and need to be proteolytically activated by cathepsins C and H. Cystatin F is the main regulator of the activity of cathepsins C and H in cytotoxic cells and, consequently, regulates their cytotoxicity. The role of cystatins and cysteine cathepsins in the immune response is presented, with emphasis on their role in the regulation of cytotoxicity of NK cells and CTLs.</p

Neonatal castration affects intrathymic kinetics of T-cell differentiation and the spleen T-cell level

To test putative interdependence in the ontogenesis of the hypothalamic-pituitary-gonadal and thymic-lymphatic axes, thymocyte differentiation and maturation was examined in neonatally castrated (Cx) adult rats. In the hypercellular thymi of Cx rats, the proportion of the least mature CD4(-)CD8(-)TCR alpha beta(-) triple negative (TN) thymocytes was reduced, while the proportions of all downstream double positive (DP) subsets (TCR alpha beta(-), TCR alpha beta(low) and TCR alpha beta(high)) were increased when compared with neonatally sham-castrated (Sx) adult rats. This suggested an accelerated thymocyte transition from the TN to DP TCR alpha beta(low) developmental stage accompanied by an increased positive/reduced negative thymocyte selection. The increased thymocyte surface density of Thy-1, which is implicated in thymocyte hyposensitivity to negative selection, in Cx rats further supports the previous assumption. The finding that the proportions of both single positive (SP) TCR alpha beta(high) thymocyte subsets were reduced, while their numbers were increased (CD4(+)CD8(-)) or unaltered (CD4(-)CD8(+)), coupled with results demonstrating an increased level of CD4(-)CD8(+) cells without changes in that of CD4(+) 8(-) cells in the spleen indicate: (i) accelerated differentiation and maturation of the positively selected DP TCR alpha beta(high) thymocytes towards CD4(-)8(+) TCR alpha beta(high) cells followed by increased emigration of the mature cells and (ii) decelerated hi h differentiation and maturation towards CD4(+)8(-) TCR alpha beta(high) cells in Cx rats. Furthermore, the unaltered proportion of intrathymically developing CD4(+)CD25(+)Foxp3(+) regulatory cells in Cx rats, in light of putative hyposensitivity of thymocytes to negative selection suggesting reduced elimination of autoreactive cells, may provide a firm basis for understanding the reasons behind increased susceptibility of Cx rats to autoimmune disease induction

Effect of solid residues from biogas plant on growth and photosynthetic characteristics of cucumber

Renewable energy sources have an important place in most European countries, with a tendency to increase their share. Biomass deriving from agricultural production is used, besides other purposes, for the production of biogass which is then used to produce electricity or for heating. Solid residues, which remain after the passage of biomass through biogass plant, are still quite voluminous and contain significant amounts of nutrients. In this regard, we studied the effect of solid residues, remained after fermentation, on growth and photosynthesis of cucumber in a semi-controlled conditions. One part of the experiment was done with solid residues as they are, and another part with composted solid residues. Mineral elements were in part supplied by nutrient solution. Significantly higher biomass of cucumber shoots was obtained in the presence of composted solid residues. With increase in amount of added solid residues increased dry weight of cucumber shoots, regardless of additional supply of nutrients through nutrient solution. Similar results were recorded for total leaf area