Matrix metalloproteinase 9 modulates immune response along with the formation of extracellular traps in flounder (Paralichthys olivaceus)

Delayed Immune Response Upon Injury in Diabetic Wounds Impedes Healing

BACKGROUND

Chronic wounds are a severe complication of diabetes. Dysregulated inflammatory signalling is thought to underly the poor healing outcomes. Yet, there is little information available on the acute response following injury and its impact on healing.

METHODS

Using a murine full thickness excisional wound model, the current study therefore assessed the expression of pro-inflammatory and pro-resolving lipid mediators during the early stages post injury in acute and diabetic wounds and compared the timeframe for transitioning through the phases of healing. Tissue eicosanoid (LTB4, PGE2, TxA2, MaR1, RvE1, RvD1, PD) and MMP-9 levels were assessed at 6 h post wounding using ELISAs. Wound closure, healing dynamics (histology), cellular infiltration and MPO, TNF-α expression (IHC) were assessed at 6 h, day2, day7 post wounding.

RESULTS

Eicosanoid expression did not differ between groups (LTB4 24-125 pg/mL, PGE2 63-177 pg/mL, TxA2 529-1184 pg/mL, MaR1 365-2052 pg/mL, RvE1 43-1157 pg/mL, RvD1 1.5-69 pg/mL, PD1 11.5-4.9 ng/mL). An inverse relationship (p < 0.05) between MMP-9 and eicosanoids were however only evident in acute and not in diabetic wounds. Diminished cellular infiltration (x5 fold) (p < 0.05) in diabetic wounds coincided with a significant delay in the expression of TNF-α (pro-inflammatory cytokine) and MPO (neutrophil marker). A significant difference in the expression of TNF-α (C 1.8 ± 0.6; DM 0.7 ± 0.1 MFI) and MPO (C 4.9 ± 1.9; DM 0.9 ± 0.4 MFI) (p < 0.05) was observed as early as 6 h post wounding, with histology parameters supporting the notion that the onset of the acute inflammatory response is delayed in diabetic wounds.

CONCLUSION

These observations imply that the immune cells are unresponsive to the initial eicosanoid expression in the diabetic wound tissue.

Comparative transcriptome analysis reveals a serotype-specific immune response in Nile tilapia (Oreochromis niloticus) infected with Streptococcus agalactiae

Streptococcus agalactiae is a major causative agent of streptococcosis in Nile tilapia (Oreochromis niloticus) and understanding its etiology is important to ensure the sustainable development of global tilapia farming. Our research group recently observed contrasting disease patterns in animals infected with two different S. agalactiae serotypes (Ib and III). To better understand the basis for these divergent responses, we analyzed the brain transcriptome of Nile tilapia following bacterial exposure. Our findings revealed significant variation in the expression of genes involved in immune (e.g., CD209 antigen, granulin, C-X-C motif chemokine 10, prostacyclin synthase, and interleukins) and neuroendocrine (e.g., mmp13a, mmp9, brain aromatase, and pmch) pathways. The serotype Ib strain seems promptly recognized by the host, triggering a potent inflammatory response, whereas the serotype III strain elicited a less immediate response, resulting in more pronounced central nervous system (CNS) symptoms and behavioral effects. To the best of our knowledge, this is the first study to show serotype-specific immune responses to S. agalactiae in Nile tilapia. These findings are important for advancing disease management and control strategies in aquaculture. Identifying different immune reactions triggered by serotypes Ib and III may assist the development of more specific approaches for preventive measures, early detection, and effective treatment against streptococcosis.

Daily crowding stress has limited, yet detectable effects on skin and head kidney gene expression in surgically tagged atlantic salmon (Salmo salar)

To ensure welfare-friendly and effective internal tagging, the tagging process should not cause a long-term burden on individuals given that tagged fish serve as representatives for the entire population in telemetry applications. To some extent, stress is inevitable within regular aquaculture practices, and thus, the consequences of long-term stress should be described in terms of their effects on internal tagging. In fish, stressors activate the Hypothalamus-Pituitary-Interrenal (HPI) and Brain-Sympathetic-Chromaffin Cell (BSC) axes, leading to neuroimmunoendocrine communication and paracrine interactions among stress hormones. The interrelation between wound healing and stress is complex, owing to their shared components, pathways, and energy demands. This study assessed 14 genes (mmp9, mmp13, il-2, il-4, il-8a, il-10, il-12, il-17d, il-1b, tnfa, ifng, leg-3, igm, and crh) in the skin (1.5 cm from the wound) and head kidney over eight weeks. These genes, associated with cell signaling in immunity, wound healing, and stress, have previously been identified as influenced and regulated by these processes. Half of a group of Atlantic salmon (n = 90) with surgically implanted dummy smart-tags were exposed to daily crowding stress. The goal was to investigate how this gene panel responds to a wound alone and then to the combined effects of wounding and daily crowding stress. Our observations indicate that chronic stress impacts inflammation and impedes wound healing, as seen through the expression of matrix metalloproteinases genes in the skin but not in the head kidney. This difference is likely due to the ongoing internal wound repair, in contrast to the externally healed wound incision. Cytokine expression, when significant in the skin, was mainly downregulated in both treatments compared to control values, particularly in the study's first half. Conversely, the head kidney showed initial cytokine downregulation followed by upregulation. Across all weeks observed and combining both tissues, the significantly expressed gene differences were 12 % between the Wound and Stress+ groups, 28 % between Wound and Control, and 25 % between Stress+ and Control. Despite significant fluctuations in cytokines, sustained variations across multiple weeks are only evident in a few select genes. Furthermore, Stress+ individuals demonstrated the most cytokine correlations within the head kidney, which may suggest that chronic stress affects cytokine expression. This investigation unveils that the presence of stress and prolonged activation of the HPI axis in an eight weeklong study has limited yet detectable effects on the selected gene expression within immunity, wound healing, and stress, with notable tissue-specific differences.

Research progress of exosomes in the angiogenesis of digestive system tumour

Malignant tumours of the digestive system cover a wide range of diseases that affect the health of people to a large extent. Angiogenesis is indispensable in the development, and metastasis of tumours, mainly in two ways: occupation or formation. Vessels can provide nutrients, oxygen, and growth factors for tumours to encourage growth and metastasis, so cancer progression depends on simultaneous angiogenesis. Recently, exosomes have been proven to participate in the angiogenesis of tumours. They influence angiogenesis by binding to tyrosine kinase receptors (VEGFR)-1, VEGFR-2, and VEGFR-3 with different affinities, regulating Yap-VEGF pathway, Akt pathway or other signaling pathway. Additionally, exosomes are potential therapeutic vectors that can deliver many types of cargoes to different cells. In this review, we summarize the roles of exosomes in the angiogenesis of digestive system tumours and highlight the clinical application prospects, directly used as targers or delivery vehicles, in antiangiogenic therapy.

Are bold-shy personalities of European perch (Perca fluviatilis) linked to stress tolerance and immunity? A scope of harnessing fish behavior in aquaculture

The sensitivity to stress and its impact on immunity are supposedly related to a fish's personality. In the present study, European perch (Perca fluviatilis) were exposed to an open-field and a novel-object test to identify distinctive shy and bold individuals. This series of cognitive tests revealed clear differences between proactive individuals with pronounced exploration behavior (bold personality) and reactive individuals that took a freeze-hide position (shy personality). A cohort of shy and bold perch was then exposed to elevated stocking density. Frozen activity and lower explorative behavior were related to higher basal and stocking-induced cortisol levels compared to proactive individuals. Since cortisol is a well-known modulator of immune-gene expression, we used multiplex real-time PCR to profile the differential immune responses to the intraperitoneal injection of Aeromonas hydrophila in the head kidney and peritoneal cells of bold and shy perch individuals. These expression differences between stimulated bold and shy perch were generally modest, except for the genes encoding the complement component c3 and the matrix metallopeptidase mmp9. The strong differential expression of these two bactericidal and inflammatory genes in the context of the modestly regulated features suggests that a fish's personality is linked to a particular immune-defense strategy. In conclusion, our approach, based on behavioral video observations, phagocytosis and enzyme assays, immunogene-expression profiling, and quantification of stress-relevant metabolites, revealed indications for divergent coping styles in cohorts of bold or shy European perch. This divergence could be exploited in future selective breeding programs.