Innate immune cell-epithelial crosstalk during wound repair

The shared mechanism of barrier dysfunction in ulcerative colitis and Alzheimer's disease: DDIT4/IL1β neutrophil extracellular traps drive macrophages-mediated phagocytosis

Ulcerative colitis (UC) and Alzheimer's disease (AD) share a common etiology as inflammatory diseases characterized by barrier deterioration. The aim of this study is to elucidate how neutrophil extracellular traps (NETs), serving as a comorbid etiological factor, can trigger the dysfunction in both the intestinal barrier and blood-brain barrier (BBB). Integrated bioinformatics analysis revealed 14 overlapped NETs-related differential expressed genes in UC and AD, which strongly featured barrier dysfunction. The following verification experiments identified enriched NETs, as well as damaged intestinal epithelium and BBB permeability, in the colon and prefrontal cortex of colitis mice and APP/PS1 mice. By employing pharmacological interventions (Cl-amidine and Disulfiram), we disrupted the formation of NETs and discovered significantly restored barrier integrity and attenuated inflammation. Further enrichment and correlation analysis indicated, for the first time, DDIT4/IL-1β NETs might drive macrophage-mediated phagocytosis to induce barrier dysfunction in UC and AD. Our findings originally established the peripheral-central inflammation interactions of UC and AD from the perspective of NETs, highlighting the potential valuable roles in gut-brain interactions and future clinic translational therapeutics.

Segmental Regulation of Intestinal Motility by Colitis and the Adaptive Immune System in the Mouse Ileum and Colon

Gastrointestinal motility disturbances are a hallmark of inflammatory bowel disease (IBD); however, their mechanisms remain unclear. This study used a dextran sulfate sodium-induced colitis mouse model, deficient in mature B and T lymphocytes, to assess intestinal motility and the role of the adaptive immune system in health and IBD. In healthy mice, the absence of adaptive lymphocytes reduced acetylcholine (ACh) sensitivity in the ileum. During colitis, it decreases motility by reducing the intensity and frequency of spontaneous contractions while increasing cholinergic responsiveness. In the proximal colon, adaptive immunity deficiency led to increased contractility and reduced ACh sensitivity in homeostasis, whereas colitis reduced contractile capacity. In the mid colon, immune-deficient mice had reduced ACh sensitivity in homeostasis and exacerbated contractile responses during colitis. In the distal colon, adaptive immunity loss reduced contractility in health and cholinergic responsiveness during colitis. These motility alterations were associated with altered acetylcholinesterase and M2/M3 muscarinic receptor expression. Notably, adaptive lymphocyte deficiency resulted in reduced tissue damage and lower tumor necrosis factor-α expression in the colon during colitis, paralleling intestinal motility changes. Overall, the adaptive immune system critically regulates motility and inflammation across different intestinal segments in IBD.

A tactfully designed photothermal agent collaborating with ascorbic acid for boosting maxillofacial wound healing

Maxillofacial injuries that may cause severe functional and aesthetic damage require effective and immediate management due to continuous exposure to diverse microbial populations. Moreover, drug resistance, biofilm formation, and oxidative stress significantly impede timely bacterial removal and immune function, making the exploration of advanced materials for maxillofacial wound healing an appealing yet highly challenging task. Herein, a near-infrared photothermal sterilization agent was designed, encapsulated with liposomes and coated with ascorbic acid known for its antioxidant and immune-regulatory functions. The resulting nanoparticles, 4TPE-C6T-TD@AA, effectively neutralize reactive oxygen species generated by lipopolysaccharides, facilitate the conversion of pro-inflammatory M1 macrophages to anti-inflammatory M2 macrophages, and eliminate >90% of Staphylococcus aureus and Escherichia coli by disrupting bacterial physiological functions upon exposure to 808 nm laser irradiation. In vivo experiments demonstrate that 4TPE-C6T-TD@AA rapidly eliminates bacteria from infected wounds in the maxillofacial region of rats, and significantly promotes healing in S. aureus-infected wounds by enhancing collagen formation and modulating the inflammatory microenvironment. In conclusion, this study presents a promising therapeutic strategy for effectively combating bacterial infections and excessive inflammation in treating maxillofacial injuries.

The role of multiomics in revealing the mechanism of skin repair and regeneration

Skin repair and regeneration are crucial processes in restoring the integrity of the skin after injury, with significant implications for medical treatments and plastic surgery. Multiomics, an integrated approach combining genomics, transcriptomics, proteomics, and metabolomics, offers unprecedented insights into the complex molecular and cellular mechanisms involved in skin healing. This review explores the transformative role of multiomics in elucidating the mechanisms of skin repair and regeneration. While genomic studies identify the genetic basis of wound healing, transcriptomics and proteomics uncover the dynamic changes in gene and protein expression, and metabolomics provides a snapshot of metabolic alterations associated with wound healing. Integrative multiomics studies can also identify novel biomarkers and therapeutic targets for skin regeneration. Despite the technical and biological challenges, the future of multiomics in skin research holds great promise for advancing personalized medicine and improving wound healing strategies. Through interdisciplinary collaboration, multiomics has the potential to revolutionize our understanding of skin repair, paving the way for innovative treatments in plastic surgery and beyond.

Rectal mucosal inflammation, microbiome, and wound healing in men who have sex with men who engage in receptive anal intercourse

Mucosal injury is common during consensual intercourse and induces an inflammatory response that could contribute to pathogen transmission including HIV. Here, we compared mucosal immune and microbiome responses to experimentally induced mucosal injury between men who have sex with men engaging in receptive anal intercourse (MSM-RAI) and men who do not engage in RAI (controls), all without HIV. Rectal mucosal secretions were collected from adult MSM-RAI (n = 19) and controls (n = 6) via anoscopy before and up to eight days after experimentally induced injury. Mucosal healing was evaluated by repeated injury surface area measurements with digital imaging. MSM-RAI demonstrated overall significantly higher concentrations of pro-inflammatory cytokines and a distinct rectal microbiome compared with controls. Wound healing was numerically faster in MSM-RAI but did not meet statistical significance (p = 0.09). Different cytokine injury response patterns were observed between MSM-RAI and controls; however, IL-6 and IP-10 were important mediators in both groups. Microbial guilds, particularly from the Lachnospiraceae and Prevotellaceae families, were associated with rectal mucosal inflammation. This work is the first experimental study of rectal mucosal injury and the immune environment in healthy humans and provides a more nuanced understanding of rectal mucosal inflammation after injury, which can inform our understanding of HIV transmission.

Depression and anxiety, peripheral blood inflammatory factors, and stress levels on therapeutic outcomes in patients with chronic wounds

BACKGROUND

The incidence of chronic wounds is rising due to an aging population and lifestyle changes in our country. In addition, as the disease spectrum evolves, chronic wounds have become common clinical issues that seriously threaten health and impose significant social and economic burdens.

AIM

To investigate how depression, anxiety, peripheral blood inflammatory factors, and stress levels affect therapeutic outcomes in patients with chronic wounds.

METHODS

Retrospectively collected clinical data from 110 patients with chronic wounds treated at Changde Hospital, Xiangya School of Medicine, Central South University (The First People's Hospital of Changde City) between January 2021 and December 2023, categorizing them into effective and ineffective groups based on treatment effects. Differences between both groups were analyzed using univariate analysis, independent risk factors identified via logistic regression, and their predictive value assessed through receiver operating characteristic analysis.

RESULTS

Following treatment, 95 cases were classified as the effective group (cured or improved), while 15 cases with improvement formed the ineffective group. Significant differences between both groups were noted in wound area, infection status, daily bed time, Hamilton Anxiety Rating Scale (HAMA) scores, Hamilton Depression Rating Scale (HAMD) scores, and levels of interleukin-6, tumor necrosis factor-alpha, and superoxide dismutase (P < 0.05). Logistic regression analysis identified a wound area ≥ 7 cm2, HAMA ≥ 9 scores, and HAMD ≥ 8 scores were independent risk factors for ineffective treatment in patients with chronic wounds (P < 0.05). The receiver operating characteristic curve analysis revealed that the area under the curve for ineffective treatment based on wound area, HAMA, and HAMD was 0.767, 0.805, and 0.768 respectively.

CONCLUSION

Wound size, anxiety, and depression are significant factors influencing the therapeutic outcomes in patients with chronic wounds that require careful attention, alongside the development of appropriate strategies.

Immunomodulatory Hydrogel for Electrostatically Capturing Pro-inflammatory Factors and Chemically Scavenging Reactive Oxygen Species in Chronic Diabetic Wound Remodeling

Diabetic wound exhibits the complex characteristics involving continuous oxidative stress and excessive expression of pro-inflammatory cytokines to cause a long-term inflammatory microenvironment. The repair healing of chronic diabetic wounding is tremendously hindered due to persistent inflammatory reaction. To address the aforementioned issues, here, a dual-functional hydrogel is designed, consisting of N1-(4-boronobenzyl)-N3-(4-boronophenyl)-N1, N1, N3, N3-tetramethylpropane-1, 3-diaminium (TSPBA) modified polyvinyl alcohol (PVA) and methacrylamide carboxymethyl chitosan (CMCSMA) can not only electrostatically adsorb proinflammatory cytokines of IL1-β and TNF-α, but can also chemically scavenge the excessive reactive oxygen species (ROS) in situ. Both in vitro and in vivo evaluations verify that the negatively charged and ROS-responsive hydrogel (NCRH) can effectively modulate the chronic inflammatory microenvironment of diabetic wounds and significantly enhance wound remodeling. More importantly, the well-designed NCRH shows a superior skin recovery in comparison with the commercial competitor product of wound dressing. Consequently, the current work highlights the need for new strategies to expedite the healing process of diabetic wounds and offers a wound dressing material with immunomodulation.

Fibroblast-Mediated Macrophage Recruitment Supports Acute Wound Healing

Epithelial and immune cells have long been appreciated for their contribution to the early immune response after injury; however, much less is known about the role of mesenchymal cells. Using single-nuclei RNA sequencing, we defined changes in gene expression associated with inflammation 1 day after wounding in mouse skin. Compared with those in keratinocytes and myeloid cells, we detected enriched expression of proinflammatory genes in fibroblasts associated with deeper layers of the skin. In particular, SCA1+ fibroblasts were enriched for numerous chemokines, including CCL2, CCL7, and IL-33, compared with SCA1- fibroblasts. Genetic deletion of Ccl2 in fibroblasts resulted in fewer wound-bed macrophages and monocytes during injury-induced inflammation, with reduced revascularization and re-epithelialization during the proliferation phase of healing. These findings highlight the important contribution of fibroblast-derived factors to injury-induced inflammation and the impact of immune cell dysregulation on subsequent tissue repair.

Promotes M1-polarization and diabetic wound healing using Prussian blue nanozymes

Long-term inflammation and impaired angiogenesis are the main reasons for the difficulty of diabetic wound healing. What to do to effectively promote vascular endothelial cell response and immune cell reprogramming is the key to diabetic skin healing. However, contemporary therapies cannot simultaneously coordinate the promotion of vascular endothelial cells and macrophage polarization, which leads to an increased rate of disability in patients with chronic diabetes. Therefore, we developed a method of repair composed of self-assembling Prussian blue nanoenzymes, which achieved synergistic support for the immune microenvironment, and also contributed to macrophage polarization in the tissue regeneration cycle, and enhanced vascular endothelial cell activity. The template hydrothermal synthesis PB-Zr nanoplatform was prepared and locally applied to wounds to accelerate wound healing through the synergistic effect of reactive oxygen species (ROS). PB-Zr significantly normalized the wound microenvironment, thereby inhibiting ROS production and inflammatory response, which may be because it inhibited the M1 polarization of macrophages in a rat model of wound. PB-Zr treatment significantly promoted the activity of vascular endothelial cells, which better promoted the growth and regeneration of other tissues in the body. The results confirmed the disease microenvironment of PB-Zr-mediated wound therapy and indicated its application in other inflammation-related diseases.

Contributions of T Cell Signaling for Wound Healing

It has long been known that T cells participate in wound healing; however, the landscape of the signaling derived from T cells in the process of wound healing is still enigmatic. With the advantages of scRNA-seq, in combination with immunofluorescent imaging, we identified activated T cells, cytotoxic T cells (CTLs), exhausting T cells, and Tregs existing in the inflammation phase of wound healing. Further analysis revealed each T cell population possess distinguished signals contributed to wound healing, some are critical for improving the wound healing quality. Besides, this study discovered and validated the existence of exhausting T cells among the T cells accumulated in the skin during wound healing, and the molecular mechanism(s) and contribution of exhausting T cells to wound healing deserve extensive studies in the future.

Dermal TRPV1 innervations engage a macrophage- and fibroblast-containing pathway to activate hair growth in mice

Pain, detected by nociceptors, is an integral part of injury, yet whether and how it can impact tissue physiology and recovery remain understudied. Here, we applied chemogenetics in mice to locally activate dermal TRPV1 innervations in naive skin and found that it triggered new regenerative cycling by dormant hair follicles (HFs). This was preceded by rapid apoptosis of dermal macrophages, mediated by the neuropeptide calcitonin gene-related peptide (CGRP). TRPV1 activation also triggered a macrophage-dependent induction of osteopontin (Spp1)-expressing dermal fibroblasts. The neuropeptide CGRP and the extracellular matrix protein Spp1 were required for the nociceptor-triggered hair growth. Finally, we showed that epidermal abrasion injury induced Spp1-expressing dermal fibroblasts and hair growth via a TRPV1 neuron and CGRP-dependent mechanism. Collectively, these data demonstrated a role for TRPV1 nociceptors in orchestrating a macrophage and fibroblast-supported mechanism to promote hair growth and enabling the efficient restoration of this mechano- and thermo-protective barrier after wounding.

Loss of Nrf2 aggravates ionizing radiation-induced intestinal injury by activating the cGAS/STING pathway via Pirin

Ionizing radiation (IR)-induced intestinal injury remains a major limiting factor in abdominal radiation therapy, and its pathogenesis remains unclear. In this study, mouse models of IR-induced intestinal injury were established, and the effect of IR on nuclear factor erythroid 2-related factor 2 (Nrf2) was determined. More severe IR-induced intestinal damage was observed in Nrf2 knockout (KO) mice than in wild-type mice. Then, the negative regulation of cyclic GMP-AMP synthase/stimulator of interferon genes (cGAS/STING) signaling by Nrf2 was examined both in vivo and in vitro after IR. This was accompanied by alterations in the intestinal neutrophil and macrophage populations in mice. Subsequently, the effect of the cGAS/STING pathway on the intestinal toxicity of IR was also investigated. Moreover, the downregulation of cGAS/STING by Nrf2 via its target gene, Pirin, was confirmed using transfection assays. A rescue experiment with Pirin was also conducted using adeno-associated virus in Nrf2 KO mice. Finally, the protective effect of calcitriol against IR-induced intestinal injury, along with increased Nrf2 and Pirin levels and decreased cGAS, pSTING, and interferon-beta levels, were observed. Taken together, our results suggest that Nrf2 alleviates IR-induced intestinal injury through Pirin-mediated inhibition of the innate immunity-related cGAS/STING pathway.

Unraveling the landscape of m6A RNA methylation in wound healing and scars

Wound healing is a complex process involving sequential stages of hemostasis, inflammation, proliferation, and remodeling. Multiple cell types and factors, including underlying conditions like diabetes and bacterial colonization, can influence healing outcomes and scar formation. N6-methyladenosine (m6A), a predominant RNA modification, plays crucial roles in gene expression regulation, impacting various biological processes and diseases. m6A regulates embryonic skin morphogenesis, wound repair, and pathophysiological processes like inflammation and angiogenesis. Recent studies have highlighted the role of m6A in wound healing, scar formation, and tissue remodeling. Additionally, m6A presents a unique expression pattern in pathological wounds and scars, potentially influencing wound healing and scar formation through modulating gene expression and cellular signaling, thereby serving as potential biomarkers or therapeutic targets. Targeting m6A modifications are potential strategies to enhance wound healing and reduce scar formation. This review aims to explore the roles and mechanisms of m6A RNA methylation in wound healing and scars, and discuss current challenges and perspectives. Continued research in this field will provide significant value for optimal wound repair and scar treatment.

Nervonic acid as novel therapeutics initiates both neurogenesis and angiogenesis for comprehensive wound repair and healing

Rapid tissue reconstruction in acute and chronic injuries are challengeable, the inefficient repair mainly due to the difficulty in simultaneous promoting the regeneration of peripheral nerves and vascular, which are closely related. Main clinical medication strategy of tissue repair depends on different cytokines to achieve nerves, blood vessels or granulation tissue regeneration, respectively. However, their effect is still limited to single aspect with biorisk exists upon long-time use. Herein, for the first time, we have demonstrated that NA isolated from Malania oleifera has potential to simultaneously promote both neurogenesis and angiogenesis in vitro and in vivo. First, NA was identified by NMR and FTIR structural characterization analysis. In a model of oxidative stress in neural cells induced by hydrogen peroxide, the cells viability of RSC96 and PC12 were protected from oxidative stress injury by NA. Similarly, based on the rat wound healing model, effective blood vessel formation and wound healing can be observed in tissue staining under NA treatment. In addition, according to the identification of nerve and vascular related markers in the wound tissue, the mechanism of NA promoting nerve regeneration lies in the upregulation of the secretion NGF, NF-200 and S100 protein, and NA treatment was also able to up-regulate VEGF and CD31 to directly promote angiogenesis during wound healing. This study provides an important candidate drug molecules for acute or chronic wound healing and nerve vascular synchronous regeneration.

Microenvironment-responsive nanomedicines: a promising direction for tissue regeneration

Severe tissue defects present formidable challenges to human health, persisting as major contributors to mortality rates. The complex pathological microenvironment, particularly the disrupted immune landscape within these defects, poses substantial hurdles to existing tissue regeneration strategies. However, the emergence of nanobiotechnology has opened a new direction in immunomodulatory nanomedicine, providing encouraging prospects for tissue regeneration and restoration. This review aims to gather recent advances in immunomodulatory nanomedicine to foster tissue regeneration. We begin by elucidating the distinctive features of the local immune microenvironment within defective tissues and its crucial role in tissue regeneration. Subsequently, we explore the design and functional properties of immunomodulatory nanosystems. Finally, we address the challenges and prospects of clinical translation in nanomedicine development, aiming to propose a potent approach to enhance tissue regeneration through synergistic immune modulation and nanomedicine integration.

The lncRNA SNHG26 drives the inflammatory-to-proliferative state transition of keratinocyte progenitor cells during wound healing

The cell transition from an inflammatory phase to a subsequent proliferative phase is crucial for wound healing, yet the driving mechanism remains unclear. By profiling lncRNA expression changes during human skin wound healing and screening lncRNA functions, we identify SNHG26 as a pivotal regulator in keratinocyte progenitors underpinning this phase transition. Snhg26-deficient mice exhibit impaired wound repair characterized by delayed re-epithelization accompanied by exacerbated inflammation. Single-cell transcriptome analysis combined with gain-of-function and loss-of-function of SNHG26 in vitro and ex vivo reveals its specific role in facilitating inflammatory-to-proliferative state transition of keratinocyte progenitors. A mechanistic study unravels that SNHG26 interacts with and relocates the transcription factor ILF2 from inflammatory genomic loci, such as JUN, IL6, IL8, and CCL20, to the genomic locus of LAMB3. Collectively, our findings suggest that lncRNAs play cardinal roles in expediting tissue repair and regeneration and may constitute an invaluable reservoir of therapeutic targets in reparative medicine.

Temperature-responsive self-contraction nanofiber/hydrogel composite dressing facilitates the healing of diabetic-infected wounds

Bacterial infections and long-term inflammation cause serious secondary damage to chronic diabetic wounds and hinder the wound healing processes. Currently, multifunctional hydrogels have shown promising effects in chronic wound repair. However, traditional hydrogels only keep the wound moist and protect it from bacterial infection, and cannot provide mechanical force to contract the wound edges to achieve facilitated wound closure. Here, an asymmetric composite dressing was created by combining biaxially oriented nanofibers and hydrogel, inspired by the double-layer structure of the traditional Chinese medicinal plaster patch, for managing chronic wounds. Specifically, electrospun Poly-(lactic acid-co-trimethylene carbonate) (PLATMC) nanofibers and methacrylate gelatin (GelMa) hydrogel loaded with Epinecidin-1@chitosan (Epi-1@CS) nanoparticles are assembled as the temperature-responsive self-contracting nanofiber/hydrogel (TSNH) composite dressing. The substrate layer of PLATMC nanofibers combines topological morphology with material properties to drive wound closure through temperature-triggered contraction force. The functional layer of GelMa hydrogel is loaded with Epi-1@CS nanoparticles that combine satisfactory cytocompatibility, and antioxidant, anti-inflammatory, and antibacterial properties. Strikingly, in vivo, the TSNH dressing could regulate the diabetic wound microenvironment, thereby promoting collagen deposition, facilitating angiogenesis, and reducing the inflammatory response, which promotes the rapid healing of chronic wounds. This study highlights the potential of synergizing mechanical and biochemical signals in enhancing chronic wound treatment. Overall, this TSNH composite dressing is provided as a reliable approach to solving the long-standing problem of chronically infected wound healing.

Trem2 acts as a non-classical receptor of interleukin-4 to promote diabetic wound healing

BACKGROUND

The immunoglobulin superfamily protein Trem2 (triggering receptor expressed on myeloid cells 2) is primarily expressed on myeloid cells where it functions to regulate macrophage-related immune response induction. While macrophages are essential mediators of diabetic wound healing, the specific regulatory role that Trem2 plays in this setting remains to be established.

OBJECTIVE

This study was developed to explore the potential importance of Trem2 signalling in diabetic wound healing and to clarify the underlying mechanisms through which it functions.

METHODS AND RESULTS

Following wound induction, diabetic model mice exhibited pronounced upregulation of Trem2 expression, which was primarily evident in macrophages. No cutaneous defects were evident in mice bearing a macrophage-specific knockout of Trem2 (T2-cKO), but they induced more pronounced inflammatory responses and failed to effectively repair cutaneous wounds, with lower levels of neovascularization, slower rates of wound closure, decreased collagen deposition following wounding. Mechanistically, we showed that interleukin (IL)-4 binds directly to Trem2, inactivating MAPK/AP-1 signalling to suppress the expression of inflammatory and chemoattractant factors. Co-culture of fibroblasts and macrophages showed that macrophages from T2-cKO mice suppressed the in vitro activation and proliferation of dermal fibroblasts through upregulation of leukaemia inhibitory factor (Lif). Injecting soluble Trem2 in vivo was also sufficient to significantly curtail inflammatory responses and to promote diabetic wound healing.

CONCLUSIONS

These analyses offer novel insight into the role of IL-4/Trem2 signalling as a mediator of myeloid cell-fibroblast crosstalk that may represent a viable therapeutic target for efforts to enhance diabetic wound healing.

Association of neutrophil-to-lymphocyte ratio with age and 180-day mortality after emergency surgery

BACKGROUND

To examine the relationship between neutrophil-to-lymphocyte ratio (NLR), age, and mortality rates after emergency surgery.

METHODS

In this observational study, a total of 851 patients undergoing emergency surgery between January 2022 and January 2023 were retrospective examined. Using 30 and 180 days mortality data, NLR differences and receiver operating characteristic (ROC) curves were analyzed using a 65-year threshold. A multiple logistic regression model was constructed incorporating age and NLR. Finally, Kaplan-Meier curves were constructed for mortality.

RESULTS

Among 851 patients, the 30 and 180 days mortality rates were 5.2% and 10.8%, respectively. Median NLR in 30 days was 5.6 (3.1 to 9.6) in survivors and 8.7 (4.6 to 13.4) in deceased patients (p < 0.0001); in 180 days, it was 5.5 (3.1 to 9.8) and 8.8 (4.8 to 14.5), respectively (p < 0.0001). In the 30- and 180-days mortality analyses, median NLRs were 5.1 (2.9 to 8.9) and 4.9 (2.9 to 8.8) in survivors and 10.6 (6.9 to 16.6) and 9.3 (5.4 to 14.9) in deceased patients aged < 65 years, respectively. The ROC AUC in patients younger than 65 years was higher for 30 days (AUC 0.75; 95% CI 0.72 to 0.87) and 180 days (AUC 0.73; 95% CI 0.64 to 0.81). Multivariate logistic regression revealed that the NLR (odds ratio, 1.03 [95% CI 1.005 to 1.053; p = 0.0133) and age (odds ratio, 1.05 [95% CI 1.034 to 1.064; p < 0.0001) significantly contributed to the model. Survival analysis revealed differences in the 180 days mortality (p = 0.0006).

CONCLUSION

We observed differences in preoperative NLR between patients who survived and those who died after emergency surgery. Age impacts the use of NLR as a mortality risk factor.

TRIAL REGISTRATION

NCT06549101, retrospectively registered.

The choroid plexus synergizes with immune cells during neuroinflammation

The choroid plexus (ChP) is a vital brain barrier and source of cerebrospinal fluid (CSF). Here, we use longitudinal two-photon imaging in awake mice and single-cell transcriptomics to elucidate the mechanisms of ChP regulation of brain inflammation. We used intracerebroventricular injections of lipopolysaccharides (LPS) to model meningitis in mice and observed that neutrophils and monocytes accumulated in the ChP stroma and surged across the epithelial barrier into the CSF. Bi-directional recruitment of monocytes from the periphery and, unexpectedly, macrophages from the CSF to the ChP helped eliminate neutrophils and repair the barrier. Transcriptomic analyses detailed the molecular steps accompanying this process and revealed that ChP epithelial cells transiently specialize to nurture immune cells, coordinating their recruitment, survival, and differentiation as well as regulation of the tight junctions that control the permeability of the ChP brain barrier. Collectively, we provide a mechanistic understanding and a comprehensive roadmap of neuroinflammation at the ChP brain barrier.

Gut mechanoimmunology: Shaping immune response through physical cues

The gut immune system embodies a complex interplay between the gut mucosal barrier, the host's immune cells, and gut microbiota. These components exist within a dynamic environment characterized by a variety of physical cues, e.g., compression, tension, shear stress, stiffness, and viscoelasticity. The physical cues can be modified under specific pathological conditions. Given their dynamic nature, comprehending the specific effects of these physical cues on the gut immune system is critical for pathological and therapeutic studies of intestinal immune-related diseases. This review aims to discuss how physical cues influence gut immunology by affecting the gut mucosal barrier, host immune cells, and gut microbiota, defining this concept as gut mechanoimmunology. This review seeks to highlight that an enhanced understanding of gut mechanoimmunology carries therapeutic implications, not only for intestinal diseases but also for extraintestinal diseases.

Interferon-gamma signaling drives epithelial TNF-alpha receptor-2 expression during colonic tissue repair

Interferon-gamma (IFNγ) is traditionally recognized for its pro-inflammatory role during intestinal inflammation. Here, we demonstrate that IFNγ also functions as a pro-repair molecule by increasing TNFα receptor 2 (TNFR2 protein/TNFRSF1B gene) expression on intestinal epithelial cells (IEC) following injury in vitro and in vivo. In silico analyses identified binding sites for the IFNγ signaling transcription factor STAT1 in the promoter region of TNFRSF1B. Scratch-wounded IEC exposed to IFNγ exhibited a STAT1-dependent increase in TNFR2 expression. In situ hybridization revealed elevated Tnfrsf1b mRNA levels in biopsy-induced colonic mucosal wounds, while intraperitoneal administration of IFNγ neutralizing antibodies following mucosal injury resulted in impaired IEC Tnfrsf1b mRNA and inhibited colonic mucosal repair. These findings challenge conventional notions that "pro-inflammatory" mediators solely exacerbate damage by highlighting latent pro-repair functions. Moreover, these results emphasize the critical importance of timing and amount in the synthesis and release of IFNγ and TNFα during the inflammatory process, as they are pivotal in restoring tissue homeostasis.

Deep skin fibroblast-mediated macrophage recruitment supports acute wound healing

Epithelial and immune cells have long been appreciated for their contribution to the early immune response after injury; however, much less is known about the role of mesenchymal cells. Using single nuclei RNA-sequencing, we defined changes in gene expression associated with inflammation at 1-day post-wounding (dpw) in mouse skin. Compared to keratinocytes and myeloid cells, we detected enriched expression of pro-inflammatory genes in fibroblasts associated with deeper layers of the skin. In particular, SCA1+ fibroblasts were enriched for numerous chemokines, including CCL2, CCL7, and IL33 compared to SCA1- fibroblasts. Genetic deletion of Ccl2 in fibroblasts resulted in fewer wound bed macrophages and monocytes during injury-induced inflammation with reduced revascularization and re-epithelialization during the proliferation phase of healing. These findings highlight the important contribution of deep skin fibroblast-derived factors to injury-induced inflammation and the impact of immune cell dysregulation on subsequent tissue repair.

Novel IL-4/HB-EGF-dependent crosstalk between eosinophils and macrophages controls liver regeneration after ischaemia and reperfusion injury

OBJECTIVE

Previous studies indicate that eosinophils are recruited into the allograft following orthotopic liver transplantation and protect from ischaemia reperfusion (IR) injury. In the current studies, we aim to explore whether their protective function could outlast during liver repair.

DESIGN

Eosinophil-deficient mice and adoptive transfer of bone marrow-derived eosinophils (bmEos) were employed to investigate the effects of eosinophils on tissue repair and regeneration after hepatic IR injury. Aside from exogenous cytokine or neutralising antibody treatments, mechanistic studies made use of a panel of mouse models of eosinophil-specific IL-4/IL-13-deletion, cell-specific IL-4rα-deletion in liver macrophages and hepatocytes and macrophage-specific deletion of heparin-binding epidermal growth factor-like growth factor (hb-egf).

RESULT

We observed that eosinophils persisted over a week following hepatic IR injury. Their peak accumulation coincided with that of hepatocyte proliferation. Functional studies showed that eosinophil deficiency was associated with a dramatic delay in liver repair, which was normalised by the adoptive transfer of bmEos. Mechanistic studies demonstrated that eosinophil-derived IL-4, but not IL-13, was critically involved in the reparative function of these cells. The data further revealed a selective role of macrophage-dependent IL-4 signalling in liver regeneration. Eosinophil-derived IL-4 stimulated macrophages to produce HB-EGF. Moreover, macrophage-specific hb-egf deletion impaired hepatocyte regeneration after IR injury.

CONCLUSION

Together, these studies uncovered an indispensable role of eosinophils in liver repair after acute injury and identified a novel crosstalk between eosinophils and macrophages through the IL-4/HB-EGF axis.

Exosomes derived from cord blood Treg cells promote diabetic wound healing by targeting monocytes

Chronic nonhealing diabetic wounds are a critical clinical challenge. Regulatory T cells (Tregs) are immunosuppressive modulators affecting wound healing progression by controlling the inflammatory response. The current study attempted to investigate whether the exosomes derived from cord blood (CB) Tregs can accelerate the healing process. Exosomes were isolated from CB-Treg cultures using ultracentrifugation and validated with different specific markers of exosomes. The purified CB-Treg-derived exosomes were co-cultured with peripheral blood mononuclear cells (PBMCs) and CD14+ monocytes. The migration-promoting effect of CB-Treg-derived exosomes on fibroblasts and endothelial cells was investigated. We used thermosensitive Pluronic F-127 hydrogel (PF-127) loaded with CB-Treg-derived exosomes in a diabetic wound healing mouse model. CB-Treg-derived exosomes with 30-120 nm diameters revealed exosome-specific markers, such as TSG101, Alix, and CD63. CB-Treg-derived exosomes were mainly bound to the monocytes when co-cultured with PBMCs, and promoted monocyte polarization to the anti-inflammatory phenotype (M2) in vitro. CB-Treg-derived exosomes enhanced the migration of endothelial cells and fibroblasts. Furthermore, CB-Treg-derived exosomes treatment accelerated wound healing by downregulating inflammatory factor levels and upregulating the M2 macrophage ratio in vivo. Our findings indicated that CB-Treg-derived exosomes could be a promising cell-free therapeutic strategy for diabetic wound healing, partly by targeting monocytes.

Bioactive lipids in the skin barrier mediate its functionality in health and disease

Our skin protects us from external threats including ultraviolet radiation, pathogens and chemicals, and prevents excessive trans-epidermal water loss. These varied activities are reliant on a vast array of lipids, many of which are unique to skin, and that support physical, microbiological and immunological barriers. The cutaneous physical barrier is dependent on a specific lipid matrix that surrounds terminally-differentiated keratinocytes in the stratum corneum. Sebum- and keratinocyte-derived lipids cover the skin's surface and support and regulate the skin microbiota. Meanwhile, lipids signal between resident and infiltrating cutaneous immune cells, driving inflammation and its resolution in response to pathogens and other threats. Lipids of particular importance include ceramides, which are crucial for stratum corneum lipid matrix formation and therefore physical barrier functionality, fatty acids, which contribute to the acidic pH of the skin surface and regulate the microbiota, as well as the stratum corneum lipid matrix, and bioactive metabolites of these fatty acids, involved in cell signalling, inflammation, and numerous other cutaneous processes. These diverse and complex lipids maintain homeostasis in healthy skin, and are implicated in many cutaneous diseases, as well as unrelated systemic conditions with skin manifestations, and processes such as ageing. Lipids also contribute to the gut-skin axis, signalling between the two barrier sites. Therefore, skin lipids provide a valuable resource for exploration of healthy cutaneous processes, local and systemic disease development and progression, and accessible biomarker discovery for systemic disease, as well as an opportunity to fully understand the relationship between the host and the skin microbiota. Investigation of skin lipids could provide diagnostic and prognostic biomarkers, and help identify new targets for interventions. Development and improvement of existing in vitro and in silico approaches to explore the cutaneous lipidome, as well as advances in skin lipidomics technologies, will facilitate ongoing progress in skin lipid research.

5-aminolevulinic acid induced photodynamic reactions in diagnosis and therapy for female lower genital tract diseases

Since the patients suffering from female lower genital tract diseases are getting younger and younger and the human papilloma virus (HPV) infection is becoming more widespread, the novel non-invasive precise modalities of diagnosis and therapy are required to remain structures of the organ and tissue, and fertility as well, by which the less damage to normal tissue and fewer adverse effects are able to be achieved. In all nucleated mammalian cells, 5-Aminolevulinic acid (5-ALA) is an amino acid that occurs spontaneously, which further synthesizes in the heme biosynthetic pathway into protoporphyrin IX (PpIX) as a porphyrin precursor and photosensitizing agent. Exogenous 5-ALA avoids the rate-limiting step in the process, causing PpIX buildup in tumor tissues. This tumor-selective PpIX distribution after 5-ALA application has been used successfully for tumor photodynamic diagnosis (PDD) and photodynamic therapy (PDT). Several ALA-based drugs have been used for ALA-PDD and ALA-PDT in treating many (pre)cancerous diseases, including the female lower genital tract diseases, yet the ALA-induced fluorescent theranostics is needed to be explored further. In this paper, we are going to review the studies of the mechanisms and applications mainly on ALA-mediated photodynamic reactions and its effectiveness in treating female lower genital tract diseases.

Focal Adhesion Kinase and Colony Stimulating Factors: Intestinal Homeostasis and Innate Immunity Crosstalk

Thousands struggle with acute and chronic intestinal injury due to various causes. Epithelial intestinal healing is dependent on phenotypic transitions to a mobile phenotype. Focal adhesion kinase (FAK) is a ubiquitous protein that is essential for cell mobility. This phenotype change is mediated by FAK activation and proves to be a promising target for pharmaceutical intervention. While FAK is crucial for intestinal healing, new evidence connects FAK with innate immunity and the importance it plays in macrophage/monocyte chemotaxis, as well as other intracellular signaling cascades. These cascades play a part in macrophage/monocyte polarization, maturation, and inflammation that is associated with intestinal injury. Colony stimulating factors (CSFs) such as macrophage colony stimulating factor (M-CSF/CSF-1) and granulocyte macrophage colony stimulating factor (GM-CSF/CSF-2) play a critical role in maintaining homeostasis within intestinal mucosa by crosstalk capabilities between macrophages and epithelial cells. The communication between these cells is imperative in orchestrating healing upon injury. Diving deeper into these connections may allow us a greater insight into the role that our immune system plays in healing, as well as a better comprehension of inflammatory diseases of the gut.

Non-TGFβ profibrotic signaling in ulcerative colitis after in vivo experimental intestinal injury in humans

Although impaired regeneration is important in many gastrointestinal diseases including ulcerative colitis (UC), the dynamics of mucosal regeneration in humans are poorly investigated. We have developed a model to study these processes in vivo in humans. Epithelial restitution (ER) and extracellular matrix (ECM) regulation after an experimental injury of the sigmoid colonic mucosa was assessed by repeated high-resolution endoscopic imaging, histological assessment, RNA sequencing, deconvolution analysis, and 16S rDNA sequencing of the injury niche microbiome of 19 patients with UC in remission and 20 control subjects. Human ER had a 48-h lag before induction of regenerative epithelial cells [wound-associated epithelial (WAE) and transit amplifying (TA) cells] along with the increase of fibroblast-derived stem cell growth factor gremlin 1 mRNA (GREM1). However, UC deconvolution data showed rapid induction of inflammatory fibroblasts and upregulation of major structural ECM collagen mRNAs along with tissue inhibitor of metalloproteinase 1 (TIMP1), suggesting increased profibrotic ECM deposition. No change was seen in transforming growth factor β (TGFβ) mRNA, whereas the profibrotic cytokines interleukin 13 (IL13) and IL11 were upregulated in UC, suggesting that human postinjury responses could be TGFβ-independent. In conclusion, we found distinct regulatory layers of regeneration in the normal human colon and a potential targetable profibrotic dysregulation in UC that could lead to long-term end-organ failure, i.e., intestinal damage.NEW & NOTEWORTHY The study reveals the regulatory dynamics of epithelial regeneration and extracellular matrix remodeling after experimental injury of the human colon in vivo and shows that human intestinal regeneration is different from data obtained from animals. A lag phase in epithelial restitution is associated with induction of stromal cell-derived epithelial growth factors. Postinjury regeneration is transforming growth factor β-independent, and we find a profibrotic response in patients with ulcerative colitis despite being in remission.

The effects of fraxetin and monnieriside A on Cultured L929 fibroblasts

Skin lesions are considered a public health problem, compromising patients' quality of life. This work aimed to evaluate the effects of fraxetin and monnieriside A on Cultured L929 Fibroblasts through the scratch assay. Supernatants and cells from the fibroblast culture treated with the compounds were used to evaluate essential markers of the tissue repair process (IGF-1, VEGF, IL-8, IL-10, FGF-2, COL1A2, COL4A, PDGF) using ELISA and qRT-PCR. The results showed that fraxetin and MOA were non-cytotoxic and could stimulate cellular migration. Fraxetin induced IGF-1, VEGF, IL-8, and IL-10 expression, while MOA induced FGF2, COL1A2, and IL-10 expression. Altogether, these results set provides evidence that fraxetin and MOA have healing potential for tissue repair, paving the way for in vivo studies and clinical trials to validate the in vitro results.

ER-mitochondria association negatively affects wound healing by regulating NLRP3 activation

Methicillin-resistant Staphylococcus aureus (MRSA) is the most common causative agent of acute bacterial skin and skin-structure infections (ABSSSI), one of the major challenges to the health system worldwide. Although the use of antibiotics as the first line of intervention for MRSA-infected wounds is recommended, important side effects could occur, including cytotoxicity or immune dysregulation, thus affecting the repair process. Here, we show that the oxazolidinone antibiotic linezolid (LZD) impairs wound healing by aberrantly increasing interleukin 1 β (IL-1β) production in keratinocytes. Mechanistically, LZD triggers a reactive oxygen species (ROS)-independent mitochondrial damage that culminates in increased tethering between the endoplasmic reticulum (ER) and mitochondria, which in turn activates the NLR family pyrin domain-containing 3 (NLRP3) inflammasome complex by promoting its assembly to the mitochondrial surface. Downregulation of ER-mitochondria contact formation is sufficient to inhibit the LZD-driven NLRP3 inflammasome activation and IL-1β production, restoring wound closure. These results identify the ER-mitochondria association as a key factor for NLRP3 activation and reveal a new mechanism in the regulation of the wound healing process that might be clinically relevant.

IL-17 Control of Cutaneous Immune Homeostasis

IL-17 is widely recognized for its roles in host defense and inflammatory disorders. However, it has become clear that IL-17 is also an essential regulator of barrier tissue physiology. Steady-state microbe sensing at the skin surface induces low-level IL-17 expression that enhances epithelial integrity and resists pathogens without causing overt inflammation. Recent reports describe novel protective roles for IL-17 in wound healing and counteracting physiologic stress; however, chronic amplification of these beneficial responses contributes to skin pathologies as diverse as fibrosis, cancer, and autoinflammation. In this paper, we discuss the context-specific roles of IL-17 in skin health and disease and therapeutic opportunities.

IL-4-induced M2 macrophages inhibit fibrosis of endometrial stromal cells

BACKGROUND

Intrauterine adhesions (IUA) refers to endometrial fibrosis caused by irreversible damage of the endometrial basal layer. As the key regulators in tissue repair, regeneration, and fibrosis, macrophages play an essential role in endometrial regeneration and repair during the normal menstrual cycle. However, the mechanism of macrophages involved in IUA remains unclear.

METHODS

In the late stages of proliferation, the endometrium was collected to make paraffin sections. HE and Masson staining were used to observing endometrial morphology and endometrial fibrosis. Immunohistochemistry and Western blotting were used to detect the expression level of fibrosis indexes COL1A1 and α-SMA. The macrophage infiltration was evaluated by immunohistochemistry for the expression levels of CD 206 and CD163. Next, we cultured the primary human endometrial stromal cells (HESCs), and then an IUA cell model was established with 10 ng/ml TGF-β1 for 72 h. THP 1 cells were differentiated by 100 ng/ml PMA into macrophages for 48 h, then macrophages were polarized to M2 macrophages by 20 ng/ml IL-4 for 24 h. The culture supernatants (M(IL-4) -S) of M2 macrophages were applied to the IUA cell model. The expression of fibrosis markers was then assessed using immunofluorescence and Western blotting.

RESULTS

The results show that Patients with IUA have fewer endometrial glands and significantly increased fibrosis levels. Moreover, the infiltration of CD206-positive (M2) macrophages was significantly reduced in IUA patients, and negatively correlated with the expression of endometrial fibrosis indexes α-SMA and COL1A1. In addition, the primary HESCs treated with 10 ng/ml TGF-β1 for 72 h were found to have significantly increased levels of fibrosis indexes. Furthermore, supernatants from IL4-induced M2 macrophages inhibit the TGF-β1-induced fibrosis of HESCs.

CONCLUSIONS

M2 macrophages may negatively regulate the expression of COL1A1 and α-SMA, inhibiting the TGF-β1-induced fibrosis of HESCs. Our study suggests that targeting macrophage phenotypes and promoting the polarization of macrophages to M2 may become a novel strategy for the clinical treatment of IUA.

A multifunctional silk-hyaluronic acid self-healing hydrogel laden with alternatively activated macrophage-derived exosomes reshape microenvironment of diabetic wound and accelerate healing

The impairment of phenotype switching of pro-inflammatory M1 to pro-healing M2 macrophage induced by hyperglycemic microenvironment often elevates oxidative stress, impairs angiogenesis, and leads to chronic non-healing wounds in diabetic patients. Administration of M2 macrophage-derived exosomes (M2Exo) at wound site is known to polarize M1 to M2 macrophage and can accelerate wound healing by enhancing collagen deposition, angiogenesis, and re-epithelialization. In the present study, M2Exo were conjugated with oxidized hyaluronic acid and mixed with PEGylated silk fibroin to develop self-healing Exo-gel to achieve an efficient therapy for diabetic wounds. Exo-gel depicted porous networked morphology with self-healing and excellent water retention behaviour. Fibroblast cells treated with Exo-gel showed significant uptake of M2Exo that increased their proliferation and migration in vitro. Interestingly, in a diabetic wound model of wistar rats, Exo-gel treatment induced 75 % wound closure within 7 days with complete epithelial layer regeneration by modulating cytokine levels, stimulating fibroblast-keratinocyte interaction and migration, angiogenesis, and organized collagen deposition. Taken together, this study suggests that Exo-gel depict properties of an excellent wound healing matrix and can be used as a therapeutic alternative to treat chronic non-healing diabetic wounds.

Molecular evidence sterile tissue damage during pathogenesis of pododermatitis aseptica hemorrhagica circumscripta is associated with disturbed epidermal-dermal homeostasis

Podermatitis aseptica hemorrhagica circumscripta is associated with metalloproteinase 2 weakening of distal phalangeal suspensory structures and sinkage of the distal phalanx in the claw capsule. Pressure from the tuberculum flexorium on the sole epidermis and dermis produces hemorrhagic tissue injury and defective horn production appearing as yellow-red, softened claw horn in region 4 of the sole. A model of the MAPK/ERK signal cascade orchestrating epidermal-dermal homeostasis was employed to determine if sterile inflammatory responses are linked to disturbed signal transduction for epidermal homeostasis in sole epidermis and dermis. The objective was to assess shifts in target genes of inflammation, up- and downstream MAPK/ERK signal elements, and targeted genes supporting epidermal proliferation and differentiation. Sole epidermis and dermis was removed from lateral claws bearing lesions of podermatitis aseptica hemorrhagica circumscripta, medial claws from the same limb and lateral claws from completely normal limbs of multiparous, lactating Holstein cows. The abundance levels of targeted transcripts were evaluated by real-time QPCR. Lesion effects were assessed by ANOVA, and mean comparisons were performed with t-tests to assess variations between mean expression in ulcer-bearing or medial claw dermis and epidermis and completely normal lateral claw dermis and epidermis or between ulcer-bearing dermis and epidermis and medial claw dermis and epidermis. The lesions were sterile and showed losses across multiple growth factors, their receptors, several downstream AP1 transcription components, CMYC, multiple cell cycle and terminal differentiation elements conducted by MAPK/ERK signals and β 4, α 6 and collagen 17A hemidesmosome components. These losses coincided with increased cytokeratin 6, β 1 integrin, proinflammatory metalloproteinases 2 and 9, IL1B and physiologic inhibitors of IL1B, the decoy receptor and receptor antagonist. Medial claw epidermis and dermis from limbs with lateral claws bearing podermatitis aseptica hemorrhagica circumscripta showed reductions in upstream MAPK/ERK signal elements and downstream targets that paralleled those in hemorrhagic lesions. Inhibitors of IL1B increased in the absence of real increases in inflammatory targets in the medial claw dermis and epidermis. Losses across multiple signal path elements and downstream targets were associated with negative effects on targeted transcripts supporting claw horn production and wound repair across lesion-bearing lateral claws and lesion-free medial claw dermis and epidermis. It was unclear if the sterile inflammation was causative or a consequence of these perturbations.

Topical lyophilized thrombin application improves wound healing for posterior spinal surgery

Background

The erector spinae plane block (ESPB) was proposed as a part of the postoperative multimodal analgesic regimen to improve pain management after posterior spinal surgery. However, ESPB might cause more surgical incisional wound exudate and poor wound healing, which might be improved after topical lyophilized thrombin application.

Materials and methods

We performed a retrospective study on patients who received posterior spinal surgery between January 2018 and December 2021. These patients were assigned into three groups: group A (general anesthesia), group B (general anesthesia with ESPB), and group C (general anesthesia with ESPB and topical 1000-unit thrombin application). Postoperative outcomes, including times of dressing changes, duration of suture removal, and incisional wound healing, were compared among these groups.

Results

Our study included 89 patients, with 48, 20, and 21 patients in groups A, B, and C, respectively. Baseline demographics, height, weight, comorbidities, and operation duration were comparable among the three groups. Group B required statistically significantly more dressing changes and had a prolonged duration of suture removal than group A (9.4 ± 4.7 versus 6.5 ± 2.0 times, 16.2 ± 3.7 versus 14.2 ± 1.4 days, respectively), which could be statistically significantly improved after the thrombin application in group C. Group B also had more frequent poor wound healing (25.0 %), which could also be improved after the thrombin application (0.0 %).

Conclusions

ESPB could cause more dressing changes and poor surgical wound healing after posterior spinal surgery, which could be improved by topical lyophilized thrombin powder application.

Rho-associated kinase regulates Langerhans cell morphology and responsiveness to tissue damage

Skin damage requires efficient immune cell responses to restore organ function. Epidermal-resident immune cells known as Langerhans cells use dendritic protrusions to surveil the skin microenvironment, which contains keratinocytes and peripheral axons. The mechanisms governing Langerhans cell dendrite dynamics and responses to tissue damage are poorly understood. Using skin explants from adult zebrafish, we show that Langerhans cells maintain normal surveillance following axonal degeneration and use their dendrites to engulf small axonal debris. By contrast, a ramified-to-rounded shape transition accommodates the engulfment of larger keratinocyte debris. We find that Langerhans cell dendrites are populated with actin and sensitive to a broad-spectrum actin inhibitor. We show that Rho-associated kinase (ROCK) inhibition leads to elongated dendrites, perturbed clearance of large debris, and reduced Langerhans cell migration to epidermal wounds. Our work describes the dynamics of Langerhans cells and involvement of the ROCK pathway in immune cell responses.

Current Knowledge and Perspectives of Phage Therapy for Combating Refractory Wound Infections

Wound infection is one of the most important factors affecting wound healing, so its effective control is critical to promote the process of wound healing. However, with the increasing prevalence of multi-drug-resistant (MDR) bacterial strains, the prevention and treatment of wound infections are now more challenging, imposing heavy medical and financial burdens on patients. Furthermore, the diminishing effectiveness of conventional antimicrobials and the declining research on new antibiotics necessitate the urgent exploration of alternative treatments for wound infections. Recently, phage therapy has been revitalized as a promising strategy to address the challenges posed by bacterial infections in the era of antibiotic resistance. The use of phage therapy in treating infectious diseases has demonstrated positive results. This review provides an overview of the mechanisms, characteristics, and delivery methods of phage therapy for combating pathogenic bacteria. Then, we focus on the clinical application of various phage therapies in managing refractory wound infections, such as diabetic foot infections, as well as traumatic, surgical, and burn wound infections. Additionally, an analysis of the potential obstacles and challenges of phage therapy in clinical practice is presented, along with corresponding strategies for addressing these issues. This review serves to enhance our understanding of phage therapy and provides innovative avenues for addressing refractory infections in wound healing.

Epithelial-neuronal-immune cell interactions: Implications for immunity, inflammation, and tissue homeostasis at mucosal sites

The epithelial lining of the respiratory tract and intestine provides a critical physical barrier to protect host tissues against environmental insults, including dietary antigens, allergens, chemicals, and microorganisms. In addition, specialized epithelial cells communicate directly with hematopoietic and neuronal cells. These epithelial-immune and epithelial-neuronal interactions control host immune responses and have important implications for inflammatory conditions associated with defects in the epithelial barrier, including asthma, allergy, and inflammatory bowel diseases. In this review, we discuss emerging research that identifies the mechanisms and impact of epithelial-immune and epithelial-neuronal cross talk in regulating immunity, inflammation, and tissue homeostasis at mucosal barrier surfaces. Understanding the regulation and impact of these pathways could provide new therapeutic targets for inflammatory diseases at mucosal sites.

Cold Atmospheric Plasma: An Emerging Immunomodulatory Therapy

Cold atmospheric plasma (CAP) is a novel technology that generates a unique combination of reactive oxygen and nitrogen species (ROS/RNS), electric fields, and UV radiation. CAP has shown promise in regulating the immune system and has potential clinical applications in wound healing, cancer treatment, and infection control. This review provides an overview of the immunological regulation activity of CAP, highlighting its substantial impact on cytokines production, immune cell phagocytosis, and immune cell proliferation. CAP has also been demonstrated to have potent therapeutic effect in anti‐inflammation, wound repair, viral and bacterial infections. Furthermore, CAP has been investigated as an adjuvant therapy for tumor treatment, eliciting a robust antitumor immune response and remarkable synergistic effects in diverse combination therapies. Further research is needed to fully understand the mechanisms underlying the effects of CAP on the immune system and to optimize its clinical application.

Biocompatible arabinogalactan-chitosan scaffolds for photothermal pharmacology in wound healing and tissue regeneration

Delayed wound healing is often caused by bacterial infections and persistent inflammation. Multifunctional materials with anti-bacterial, anti-inflammatory, and hemostatic properties are crucial for accelerated wound healing. In this study, we report a biomacromolecule-based scaffold (ArCh) by uniquely combining arabinogalactan (Ar) and chitosan (Ch) using a Schiff-based reaction. Further, the optimized ArCh scaffolds were loaded with Glycyrrhizin (GA: anti-inflammatory molecule) conjugated NIR light-absorbing Copper sulfide (CuS) nanoparticles. The resultant GACuS ArCh scaffolds were characterized for different wound healing parameters in in-vitro and in-vivo models. Our results indicated that GACuS ArCh scaffolds showed excellent swelling, biodegradation, and biocompatibility in vitro. Further results obtained indicated that GACuS ArCh scaffolds demonstrated mild hyperthermia and enhanced hemostatic, anti-oxidant, anti-bacterial, and wound-healing effects when exposed to NIR light. The scaffolds, upon further validation, may be beneficial in accelerating wound healing and tissue regeneration response.

Inhibition of Pck1 in intestinal epithelial cells alleviates acute pancreatitis via modulating intestinal homeostasis

Intestinal barrier dysfunction usually occurred in acute pancreatitis (AP) but the mechanism remains unclear. In this study, RNA sequencing of ileum in L-arginine-induced AP mice demonstrated that phosphoenolpyruvate kinase 1 (Pck1) was significantly up-regulated. Increased Pck1 expression in intestinal epithelial cells (IECs) was further validated in ileum of AP mice and duodenum of AP patients. In AP mice, level of Pck1 was positively correlated with pancreatic and ileal histopathological scores, serum amylase activity, and intestinal permeability (serum diamine oxidase (DAO), D-lactate, and endotoxin). In AP patients, level of Pck1 had a positive correlation with Ranson scores, white blood cell count and C-reactive protein. Inhibition of Pck1 by 3-Mercaptopicolinic acid hydrochloride (3-MPA) alleviated pancreatic and ileal injuries in AP mice. AP + 3-MPA mice showed improved intestinal permeability, including less epithelial apoptosis, increased tight junction proteins (TJPs) expression, decreased serum DAO, D-lactate, endotoxin, and FITC-Dextran levels, and reduced bacteria translocation. Lysozyme secreted by Paneth cells and mucin2 (MUC2) secretion in goblet cells were also partly restored in AP + 3-MPA mice. Meanwhile, inhibition of Pck1 improved intestinal immune response during AP, including elevation of M2/M1 macrophages ratio and secretory immunoglobulin A (sIgA) and reduction in neutrophils infiltration. In vitro, administration of 3-MPA dramatically ameliorated inflammation and injuries of epithelial cells in enteroids treated by LPS. In conclusion, inhibition of Pck1 in IECs might alleviate AP via modulating intestinal homeostasis.

Host-Microbiome Crosstalk in Chronic Wound Healing

The pathogenesis of chronic wounds (CW) involves a multifaceted interplay of biochemical, immunological, hematological, and microbiological interactions. Biofilm development is a significant virulence trait which enhances microbial survival and pathogenicity and has various implications on the development and management of CW. Biofilms induce a prolonged suboptimal inflammation in the wound microenvironment, associated with delayed healing. The composition of wound fluid (WF) adds more complexity to the subject, with proven pro-inflammatory properties and an intricate crosstalk among cytokines, chemokines, microRNAs, proteases, growth factors, and ECM components. One approach to achieve information on the mechanisms of disease progression and therapeutic response is the use of multiple high-throughput 'OMIC' modalities (genomic, proteomic, lipidomic, metabolomic assays), facilitating the discovery of potential biomarkers for wound healing, which may represent a breakthrough in this field and a major help in addressing delayed wound healing. In this review article, we aim to summarize the current progress achieved in host-microbiome crosstalk in the spectrum of CW healing and highlight future innovative strategies to boost the host immune response against infections, focusing on the interaction between pathogens and their hosts (for instance, by harnessing microorganisms like probiotics), which may serve as the prospective advancement of vaccines and treatments against infections.

Smad4 Loss in the Mouse Intestinal Epithelium Alleviates the Pathological Fibrotic Response to Injury in the Colon

Mucosal healing is associated with better clinical outcomes in patients with inflammatory bowel diseases (IBDs). Unresolved injury and inflammation, on the other hand, increases pathological fibrosis and the predisposition to cancer. Loss of Smad4, a tumor suppressor, is known to increase colitis-associated cancer in mouse models of chronic IBD. Since common biological processes are involved in both injury repair and tumor growth, we sought to investigate the effect of Smad4 loss on the response to epithelial injury. To this end, Smad4 was knocked out specifically in the intestinal epithelium and transcriptomic and morphological changes compared between wild type mice and Smad4 knock out mice after DSS-induced injury. We find that Smad4 loss alleviates pathological fibrosis and enhances mucosal repair. The transcriptomic changes specific to epithelium indicate molecular changes that affect epithelial extracellular matrix (ECM) and promote enhanced mucosal repair. These findings suggest that the biological processes that promote wound healing alleviate the pathological fibrotic response to DSS. Therefore, these mucosal repair processes could be exploited to develop therapies that promote normal wound healing and prevent fibrosis.

NEW AND NOTEWORTHY

We show that transcriptomic changes due to Smad4 loss in the colonic epithelium alleviates the pathological fibrotic response to DSS in an IBD mouse model of acute inflammation. Most notably, we find that collagen deposition in the epithelial ECM, as opposed to that in the lamina propria, correlates with epithelial changes that enhance wound healing. This is the first report on a mouse model providing alleviated fibrotic response in a DSS-IBD mouse model in vivo .

Immune cell-derived signals governing epithelial phenotypes in homeostasis and inflammation

The intestinal epithelium fulfills important physiological functions and forms a physical barrier to the intestinal lumen. Barrier function is regulated by several pathways, and its impairment contributes to the pathogenesis of inflammatory bowel disease (IBD), a chronic inflammatory condition affecting more than seven million people worldwide. Current treatment options specifically target inflammatory mediators and have led to improvement of clinical outcomes; however, a significant proportion of patients experience treatment failure. Pro-repair effects of inflammatory mediators on the epithelium are emerging. In this review we summarize current knowledge on involved epithelial pathways, identify open questions, and put recent findings into clinical perspective, and pro-repair effects. A detailed understanding of epithelial pathways integrating mucosal stimuli in homeostasis and inflammation is crucial for the development of novel, more targeted therapies.

Effects of various cross-linked collagen scaffolds on wound healing in rats model by deep-learning CNN

Scar tissue is connective tissue formed on the wound during the wound-healing process. The most significant distinction between scar tissue and normal tissue is the appearance of covalent cross-linking and the amount of collagen fibers in the tissue. This study investigates the efficacy of four types of collagen scaffolds in promoting wound healing and regeneration in a Sprague-Dawley murine model-the histomorphology analysis of collagen scaffolds and developing a deep learning model for accurate tissue classification. Four female rats (n = 24) groups received collagen scaffolds prepared through physical and chemical crosslinking. Wound healing progress was evaluated by monitoring granulation tissue formation, collagen matrix organization, and collagen fiber deposition, with histological scoring for quantification-the EDC and HA groups demonstrated enhanced tissue regeneration. The EDC and HA groups observed significant differences in wound regeneration outcomes. Deep-learning CNN models with data augmentation techniques were used for image analysis to enhance objectivity. The CNN architecture featured pre-trained VGG16 layers and global average pooling (GAP) layers. Feature visualization using Grad-CAM heatmaps provided insights into the neural network's focus on specific wound features. The model's AUC score of 0.982 attests to its precision. In summary, collagen scaffolds can promote wound healing in mice, and the deep learning image analysis method we proposed may be a new method for wound healing assessment.

Recent advances of hydrogels as smart dressings for diabetic wounds

Chronic diabetic wounds have been an urgent clinical problem, and wound dressings play an important role in their management. Due to the design of traditional dressings, it is difficult to achieve adaptive adhesion and on-demand removal of complex diabetic wounds, real-time monitoring of wound status, and dynamic adjustment of drug release behavior according to the wound microenvironment. Smart hydrogels, as smart dressings, can respond to environmental stimuli and achieve more precise local treatment. Here, we review the latest progress of smart hydrogels in wound bandaging, dynamic monitoring, and drug delivery for treatment of diabetic wounds. It is worth noting that we have summarized the most important properties of smart hydrogels for diabetic wound healing. In addition, we discuss the unresolved challenges and future prospects in this field. We hope that this review will contribute to furthering progress on smart hydrogels as improved dressing for diabetic wound healing and practical clinical application.

Facile preparation of self-healing hydrogels based on chitosan and PVA with the incorporation of curcumin-loaded micelles for wound dressings

The increased demand for improved strategies for wound healing has, in recent years, motivated the development of multifunctional hydrogels with favorable bio-compatibility and antibacterial properties. To this regard, the current study presented the design of a novel self-healing composite hydrogel that could perform as wound dressing for the promotion of wound healing. The composite hydrogels were composed of polyvinyl alcohol (PVA), borax and chitosan functionalized with sialic acid (SA-CS) and curcumin loaded pluronic F127 micelles. The hydrogels were formed through the boronic ester bond formation between PVA, SA-CS and borax under physiological conditions and demonstrated adjustable mechanical properties, gelation kinetics and antibacterial properties. When incubating with NIH3T3 cells, the hydrogels also demonstrated good biocompatibility. These aspects offer a promising foundation for their prospective applications in developing clinical materials for wound healing.

Biological processes and factors involved in soft and hard tissue healing

Wound healing is a complex and iterative process involving myriad cellular and biologic processes that are highly regulated to allow satisfactory repair and regeneration of damaged tissues. This review is intended to be an introductory chapter in a volume focusing on the use of platelet concentrates for tissue regeneration. In order to fully appreciate the clinical utility of these preparations, a sound understanding of the processes and factors involved in soft and hard tissue healing. This encompasses an appreciation of the cellular and biological mediators of both soft and hard tissues in general as well as specific consideration of the periodontal tissues. In light of good advances in this basic knowledge, there have been improvements in clinical strategies and therapeutic management of wound repair and regeneration. The use of platelet concentrates for tissue regeneration offers one such strategy and is based on the principles of cellular and biologic principles of wound repair discussed in this review.

Investigating Inflammatory Markers in Wound Healing: Understanding Implications and Identifying Artifacts

Understanding the complex interplay of pro-inflammatory and anti-inflammatory cytokines is crucial in the field of wound healing, as it holds the key to developing effective therapeutics. In the initial stages of wound healing, pro-inflammatory cytokines like IL-1β, IL-6, TNF-α, and various chemokines play vital roles in recruiting cells for debris clearance and the recruitment of growth factors. Careful regulation and timely resolution of this early inflammation are essential for optimal wound repair. As the healing process progresses, anti-inflammatory proteins such as IL-10 and IL-4 become instrumental in facilitating the transition to later stages where pro-inflammatory cytokines promote angiogenesis and wound remodeling. This Perspective underscores the complexity of inflammatory cytokines in wound healing research and emphasizes the need for comprehensive and unbiased methodologies in their evaluation. For robust and reliable results in wound-healing research, a more holistic approach is necessary-one that considers the roles, interactions, and timing of biological molecules, alongside careful sampling and evaluation strategies.