Yoji Hakamata

Hemozoin (Hz) is a heme crystal produced during malaria infection that stimulates immune cells, leading to the production of cytokines and chemokines. The immunostimulatory action of Hz has previously been applied in the development of alternative adjuvants. Crystallization of hemin is a chemical approach for producing Hz. Here, we focused on an enzymatic production method for Hz using the heme detoxification protein (HDP), which catalyzes heme dimer formation from hemin in Plasmodium. We examined the immunostimulatory effects of an enzymatically synthesized analog of Hz (esHz) produced by recombinant Plasmodium falciparum HDP. Enzymatically synthesized Hz stimulates a macrophage cell line and human peripheral mononuclear cells, leading to the production of interleukin (IL)-6 and IL-12p40. In mice, subcutaneous administration of esHz together with an antigen, ovalbumin (OVA), increased the OVA-specific immunoglobulin (Ig) G2c isotype level in the serum, whereas OVA-specific IgG1 was not induced. Our findings suggest that esHz is a useful Th-1 cell adjuvant.

Fireflies produce light through luciferase-catalyzed reactions involving luciferin, oxygen, and adenosine triphosphate, distinct from other luminescent organisms. This unique feature has revolutionized molecular biology and physiology, serving as a valuable tool for cellular research. Luciferase-based bioluminescent imaging enabled the creation of transgenic animals, such as Firefly Rats. Firefly Rats, created in 2006, ubiquitously express luciferase and have become a critical asset in scientific investigations. These rats have significantly contributed to transplantation and tissue engineering studies. Their low immunogenicity reduces graft rejection risk, making them ideal for long-term tracking of organ/tissue/cellular engraftments. Importantly, in the islet transplantation setting, the ubiquitous luciferase expression in these rats does not alter islet morphology or function, ensuring accurate assessments of engrafted islets. Firefly Rats have illuminated the path of transplantation research worldwide for over a decade and continue accelerating scientific advancements in many fields.

PURPOSE: To develop a new 4/6 infarct nephrectomy (INx) model rat mimicking moderate chronic kidney disease (CKD) and to evaluate its application. METHODS: We modified the conventional 5/6 INx rat model to create the 4/6 INx model by ligating the renal artery branch to induce infarction of one-third of the left kidney after right kidney removal and compared biochemically and histologically both models. To demonstrate the application of the 4/6 INx model, the effects of a supplementary compound containing calcium carbonate, chitosan, palm shell activated charcoal etc., that is effective for both CKD and its complications, were compared between both models. RESULTS: Impairment of renal function in the 4/6 INx group was significantly more moderate than in the 5/6 INx group (P < 0.05). The 4/6 INx group showed less histological damage in kidney than in the 5/6 INx group. The supplementary compound did not improve CKD in the 5/6 INx group, but ameliorated elevation of blood urea nitrogen in the 4/6 INx group. CONCLUSIONS: We developed the 4/6 INx model, which is more moderate than the conventional 5/6 INx model. This model could potentially demonstrate the effectiveness of drugs and supplements intended to prevent CKD and its progression.