Omentum picture: unraveling the enigma of the immune microenvironment in appendicitis scenario

Authors

  • Márcio Gaspar Clínica Multiperfil, Luanda, Angola; Associate Laboratory i4HB - Institute for Health and Bioeconomy, University Institute of Health Sciences - CESPU, 4585-116 Gandra, Portugal; UCIBIO - Applied Molecular Biosciences Unit, Toxicologic Pathology Research Laboratory, University Institute of Health Sciences (1H-TOXRUN, IUCS-CESPU), 4585-116 Gandra, Portugal
  • Tomás Rodrigues University Institute of Health Sciences (IUCS), Rua Central de Gandra, 1317, 4585-116, Gandra, PRD, Portugal
  • Ana Rita Nunes University Institute of Health Sciences (IUCS), Rua Central de Gandra, 1317, 4585-116, Gandra, PRD, Portugal
  • Fernanda Garcez UNIPRO – Oral Pathology and Rehabilitation Research Unit, University Institute of Health Sciences, CESPU, CRL, 4585-116 Gandra, Portugal
  • Sara Ricardo Associate Laboratory i4HB - Institute for Health and Bioeconomy, University Institute of Health Sciences - CESPU, 4585-116 Gandra, Portugal; UCIBIO - Applied Molecular Biosciences Unit, Toxicologic Pathology Research Laboratory, University Institute of Health Sciences (1H-TOXRUN, IUCS-CESPU), 4585-116 Gandra, Portugal; UNIPRO – Oral Pathology and Rehabilitation Research Unit, University Institute of Health Sciences, CESPU, CRL, 4585-116 Gandra, Portugal
  • Carla Batista-Pinto Associate Laboratory i4HB - Institute for Health and Bioeconomy, University Institute of Health Sciences - CESPU, 4585-116 Gandra, Portugal; UCIBIO - Applied Molecular Biosciences Unit, Toxicologic Pathology Research Laboratory, University Institute of Health Sciences (1H-TOXRUN, IUCS-CESPU), 4585-116 Gandra, Portugal; UNIPRO – Oral Pathology and Rehabilitation Research Unit, University Institute of Health Sciences, CESPU, CRL, 4585-116 Gandra, Portugal; Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), University of Porto, Terminal de Cruzeiros do Porto de Leixões, 4450-208 Matosinhos, Portugal
  • Albina Dolores Resende Associate Laboratory i4HB - Institute for Health and Bioeconomy, University Institute of Health Sciences - CESPU, 4585-116 Gandra, Portugal; UCIBIO - Applied Molecular Biosciences Unit, Toxicologic Pathology Research Laboratory, University Institute of Health Sciences (1H-TOXRUN, IUCS-CESPU), 4585-116 Gandra, Portugal; UNIPRO – Oral Pathology and Rehabilitation Research Unit, University Institute of Health Sciences, CESPU, CRL, 4585-116 Gandra, Portugal; Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), University of Porto, Terminal de Cruzeiros do Porto de Leixões, 4450-208 Matosinhos, Portugal https://orcid.org/0000-0003-4644-1867

DOI:

https://doi.org/10.48797/sl.2024.173

Keywords:

Poster

Abstract

Background: Appendix obstruction triggers inflammation and exaggerated immune responses, leading the omentum, rich in Milky Spots (MS) housing immune cells, to play a vital role in peritoneal immunity. These MS collect antigens and pathogens, inducing immune responses like inflammation, immune tolerance, or fibrosis [1,2]. Their activities, including angiogenesis, stem cell differentiation, and immune responses, are essential for wound healing and infection containment. However, these activities may also promote pathological responses like rapid tumor growth and metastasis [1,3]. Omental MS contribute to tissue homeostasis, aiding tissue repair through the regulation of leukocyte recruitment and activation by specialized stromal fibroblasts and mesothelial cells [1,3,4]. Objective: This study aims to semi-quantitatively evaluate leukocyte subpopulations and extracellular matrix composition in omentum samples from three acute appendicitis patients’ groups: Group I without peritoneal blockage, Group II with peritoneal blockage, and the control Group III. Methods: Histological omentum samples underwent staining techniques with H&E, Trichrome, Orcein, and Reticulin for optical microscopy analysis. Results: Observations revealed higher presence of polymorphonuclear cells and/or lymphocytes, increased fibrosis, and abundant extracellular matrix reticular fibers. The control group exhibited minimal polymorphonuclear cells, lymphocytes, or fibrosis, while groups I and II showed increased polymorphonuclear cells, lymphocytes, and reticular fibers. Collagen fibers demonstrated a similar trend, albeit at lower density, while elastic fibers were scarce. These findings indicate a consistent association among the patient groups: while the control group showed low leukocyte counts and minimal fibrosis, groups I and II, characterized by increased fibrosis, demonstrated elevated leukocyte numbers and a greater presence of reticular fibers. Conclusions: These findings align with literature, emphasizing the omentum’s crucial role in maintaining tissue homeostasis and supporting tissue repair through the regulation of leukocyte recruitment and activation by specialized fibroblastic stromal cells and mesothelial cells [3,4]. Further studies characterizing the omentum microenvironment are essential for identifying response predictive biomarkers.

References

1. Meza-Perez, S.; Randall, T.D. Immunological Functions of the Omentum. Trends Immunol 2017, 38(7), 526–536

2. Shah, S.; Lowery, E.; Braun, R.K.; Martin, A.; Huang, N.; Medina, M.; Sethupathi, P.; Seki, Y.; Takami, M.; Byrne, K.; Wigfield, C.; Love, R.B.; Iwashima, M. Cellular basis of tissue regeneration by omentum. PLOS ONE 2012, 7(6), e38368.

3. Liu, M.; Silva-Sanchez, A.; Randall, T.D.; Meza-Perez, S. Specialized immune responses in the peritoneal cavity and omentum. J Leukoc Biol 2021, 109(4), 717–729.

4. Louwe, P.A.; Forbes, S.J.; Bénézech, C.; Pridans, C.; Jenkins, S.J. Cell origin and niche availability dictate the capacity of peritoneal macrophages to colonize the cavity and omentum. Immunol 2022, 166(4), 458–474.

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Published

2024-05-01

How to Cite

Gaspar, M., Rodrigues, T., Nunes, A. R., Garcez, F., Ricardo, S., Batista-Pinto, C., & Resende, A. D. (2024). Omentum picture: unraveling the enigma of the immune microenvironment in appendicitis scenario. Scientific Letters, 1(Sup 1). https://doi.org/10.48797/sl.2024.173

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