Neuro-immune lessons from an annelid: The medicinal leech

An important question that remains unanswered is how the vertebrate neuroimmune system can be both friend and foe to the damaged nervous tissue. Some of the difficulty in obtaining responses in mammals probably lies in the conflation in the central nervous system (CNS), of the innate and adaptive immune responses, which makes the vertebrate neuroimmune response quite complex and difficult to dissect. An alternative strategy for understanding the relation between neural immunity and neural repair is to study an animal devoid of adaptive immunity and whose CNS is well described and regeneration competent. The medicinal leech offers such opportunity. If the nerve cord of this annelid is crushed or partially cut, axons grow across the lesion and conduction of signals through the damaged region is restored within a few days, even when the nerve cord is removed from the animal and maintained in culture. When the mammalian spinal cord is injured, regeneration of normal connections is more or less successful and implies multiple events that still remain difficult to resolve. Interestingly, the regenerative process of the leech lesioned nerve cord is even more successful under septic than under sterile conditions suggesting that a controlled initiation of an infectious response may be a critical event for the regeneration of normal CNS functions in the leech. Here are reviewed and discussed data explaining how the leech nerve cord sensu stricto (i.e. excluding microglia and infiltrated blood cells) recognizes and responds to microbes and mechanical damages.

Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.

Review of medicinal leech CNS neuro-immune responses to microbes and damage, with regeneration enhanced under septic conditions, providing alternative model to mammalian adaptive immunity.

Explore how this research connects to clinical practice

More peer-reviewed studies in Antimicrobial Resistance.

• Novel Leech Antimicrobial Peptides — Hirunipins — Kumar et al. (2025)
• Leech therapy (Hirudo medicinalis) attenuates testicular damages induced by testicular ischemia/reperfusion in an animal model — Davoodi F et al. (2021)
• AIF-1 and RNASET2 Play Complementary Roles in the Innate Immune Response of Medicinal Leech — Baranzini N et al. (2019)
• Medicinal leech antimicrobial peptides lacking toxicity represent a promising alternative strategy to combat antibiotic-resistant pathogens — Grafskaia E et al. (2019)
• Antimicrobial Role of RNASET2 Protein During Innate Immune Response in the Medicinal Leech — Baranzini N et al. (2020)
• Morganella Morganii Infection in Hirudo Medicinalis (Iran): A Case Report — Rahmati Holasoo H et al. (2022)
• Clinical efficacy of Jalaukawacharana (leech application) in Thrombosed piles — Bhagat P, Raut S, Lakhapati A (2012)
• Determination of disulfide linkages in antimicrobial peptides of the macin family by combination of top-down and bottom-up proteomics — Hung CW, Jung S, Grötzinger J, Gelhaus C, Leippe M, Tholey A (2014)
• Molecular characterization of two novel antibacterial peptides inducible upon bacterial challenge in an annelid, the leech Theromyzon tessulatum — Tasiemski A, Vandenbulcke F, Mitta G, Lemoine J, Lefebvre C, Sautière PE, Salzet M (2004)
• Macin family of antimicrobial proteins combines antimicrobial and nerve repair activities — Jung S, Sönnichsen FD, Hung CW et al. (2012)

Browse all ASH-analysed research →