ABSTRACT
Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the activation of the immune response against self antigens. Numerous reproductive complications, including reduced birth rate and complications for the mother and the fetus during pregnancy, have been observed in women with SLE. In the present study, we aimed to investigate the effect of SLE development on oocyte meiosis in lupus-prone mice. Lupus-prone MRL/lpr mice were used for the experiments: disease-free (4 weeks of age) and sick (20 weeks of age, virgin and postpartum). The immune response was monitored by flow cytometry, ELISpot, ELISA, and histology. Oocytes were analyzed by fluorescence microscopy based on chromatin, tubulin, and actin structures. The lupus-prone MRL/lpr mice developed age-dependent symptoms of SLE with increased levels of various autoantibodies, proteinuria, and renal infiltrates and a tendency for the immune response to worsen with changes in cell populations and the cytokine profile. The number and quality of oocytes were also affected, and the successful pregnancy rate of MRL/lpr mice was limited to only 60%. Isolated oocytes showed severe structural changes in all studied groups. Systemic alterations in immune homeostasis in SLE affect the quality of developing oocytes, which is evident from a young age. The data obtained is in line with the trend of reduced fertility in lupus-prone MRL/lpr mice. The phenomenon can be explained by changes in the microenvironment of the relevant organs and close connection between ovulation and inflammatory processes.
ABSTRACT
Known as a degenerative joint disorder of advanced age affecting predominantly females, osteoarthritis can develop in younger and actively working people because of activities involving loading and injuries of joints. Collagenase-induced osteoarthritis (CIOA) in a mouse model allowed us to investigate for the first time its effects on key cytoskeletal structures (meiotic spindles and actin distribution) of ovulated mouse oocytes. Their meiotic spindles, actin caps, and chromatin were analyzed by immunofluorescence. A total of 193 oocytes from mice with CIOA and 209 from control animals were obtained, almost all in metaphase I (M I) or metaphase II (MII). The maturation rate was lower in CIOA (26.42% M II) than in controls (55.50% M II). CIOA oocytes had significantly larger spindles (average 37 µm versus 25 µm in controls, p < 0.001), with a proportion of large spindles more than 64% in CIOA versus up to 15% in controls (p < 0.001). Meiotic spindles were wider in 68.35% M I and 54.90% M II of CIOA oocytes (mean 18.04 µm M I and 17.34 µm M II versus controls: 11.64 µm M I and 12.64 µm M II), and their poles were approximately two times broader (mean 6.9 µm) in CIOA than in controls (3.6 µm). CIOA oocytes often contained disoriented microtubules. Actin cap was visible in over 91% of controls and less than 20% of CIOA oocytes. Many CIOA oocytes without an actin cap had a nonpolarized thick peripheral actin ring (61.87% of M I and 52.94% of M II). Chromosome alignment was normal in more than 82% in both groups. In conclusion, CIOA affects the cytoskeleton of ovulated mouse oocytes-meiotic spindles are longer and wider, their poles are broader and with disorganized fibers, and the actin cap is replaced by a broad nonpolarized ring. Nevertheless, meiotic spindles were successfully formed in CIOA oocytes and, even when abnormal, allowed correct alignment of chromosomes.
ABSTRACT
Systemic lupus erythematosus (SLE) is a chronic systemic autoimmune disease characterized by generation of autoantibodies and severe damage of various organs. The hormonal changes associated with pregnancy and especially estrogen might lead to damage of reproductive function and ovarian quality. We employed a pristane-induced lupus model of Balb/c mice which resembles human lupus in an attempt to follow oogenesis disruption during the disease progression. The integrity of cytoskeletal and chromatin structures was estimated in oocytes derived by hormonally stimulated ovulation in lupus mice and the results were compared with those from healthy mice. Chromatin, tubulin and actin structures in oocytes were detected by Hoechst 33258, anti-alpha-tubulin antibody and rhodamine-labeled phalloidin, respectively. All available meiotic spindles were analyzed - in immature (metaphase I) and mature oocytes (metaphase II). The total number of mature oocytes obtained from lupus mice was lower compared to healthy controls. The maturation rate was 9.8 % for lupus mice, 12.7 % for 7-month old controls, and 14.3 % for the young control mice (4 weeks old). Another major difference between the studied groups was the higher percentage of defective metaphase I spindles registered in oocytes derived from lupus mice (60 % normal spindles), while for the young and older controls this proportion was 86 % and 81 %, respectively. No such difference was registered for metaphase II spindles. For both metaphase I and metaphase II oocytes, the proportions of normal actin cap and chromosomal condensation were similar between the experimental groups.
