TY - JOUR

T1 - Lymph Nodes Draining Infections Investigated by PET and Immunohistochemistry in a Juvenile Porcine Model

AU - Afzelius, Pia

AU - Morsing, Malene Kjelin

AU - Nielsen, Ole Lerberg

AU - Alstrup, Aage Kristian Olsen

AU - Jensen, Svend Borup

AU - Jødal, Lars

N1 - Publisher Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

PY - 2022

Y1 - 2022

N2 - Background: [18 F]FDG and [11 C]methionine accumulate in lymph nodes draining S. aureus-infected foci. The lymph nodes were characterized by weight, [11 C]methionine-and [18 F]FDG-positron emissions tomography (PET)/computed tomography (CT), and immunohistochemical (IHC)-staining. Methods: 20 pigs inoculated with S. aureus into the right femoral artery were PET/CT-scanned with [18 F]FDG, and nine of the pigs were additionally scanned with [11 C]methionine. Mammary, medial iliac, and popliteal lymph nodes from the left and right hind limbs were weighed. IHC-staining for calculations of area fractions of Ki-67, L1, and IL-8 positive cells was done in mammary and popliteal lymph nodes from the nine pigs. Results: The pigs developed one to six osteomyelitis foci. Some pigs developed contiguous infections of peri-osseous tissue and inoculationsite abscesses. Weights of mammary and medial iliac lymph nodes and their [18 F]FDG maximum Standardized Uptake Values (SUVFDGmax) showed a significant increase in the inoculated limb compared to the left limb. Popliteal lymph node weight and their FDG uptake did not differ significantly between hind limbs. Area fractions of Ki-67 and IL-8 in the right mammary lymph nodes and SUVMetmax in the right popliteal lymph nodes were significantly increased compared with the left side. Conclusion: The PET-tracers [18 F]FDG and [11 C]methionine, and the IHC-markers Ki-67 and IL-8, but not L1, showed increased values in lymph nodes draining soft tissues infected with S. aureus. The increase in [11 C]methionine may indicate a more acute lymph node response, whereas an increase in [18 F]FDG may indicate a more chronic response.

AB - Background: [18 F]FDG and [11 C]methionine accumulate in lymph nodes draining S. aureus-infected foci. The lymph nodes were characterized by weight, [11 C]methionine-and [18 F]FDG-positron emissions tomography (PET)/computed tomography (CT), and immunohistochemical (IHC)-staining. Methods: 20 pigs inoculated with S. aureus into the right femoral artery were PET/CT-scanned with [18 F]FDG, and nine of the pigs were additionally scanned with [11 C]methionine. Mammary, medial iliac, and popliteal lymph nodes from the left and right hind limbs were weighed. IHC-staining for calculations of area fractions of Ki-67, L1, and IL-8 positive cells was done in mammary and popliteal lymph nodes from the nine pigs. Results: The pigs developed one to six osteomyelitis foci. Some pigs developed contiguous infections of peri-osseous tissue and inoculationsite abscesses. Weights of mammary and medial iliac lymph nodes and their [18 F]FDG maximum Standardized Uptake Values (SUVFDGmax) showed a significant increase in the inoculated limb compared to the left limb. Popliteal lymph node weight and their FDG uptake did not differ significantly between hind limbs. Area fractions of Ki-67 and IL-8 in the right mammary lymph nodes and SUVMetmax in the right popliteal lymph nodes were significantly increased compared with the left side. Conclusion: The PET-tracers [18 F]FDG and [11 C]methionine, and the IHC-markers Ki-67 and IL-8, but not L1, showed increased values in lymph nodes draining soft tissues infected with S. aureus. The increase in [11 C]methionine may indicate a more acute lymph node response, whereas an increase in [18 F]FDG may indicate a more chronic response.

KW - calcium-binding leukocyte L1

KW - IL-8

KW - immunohistochemistry

KW - Ki-67

KW - lymph nodes

KW - PET

KW - pig model

KW - Staphylococcus aureus

KW - [ C]methionine

KW - [ F]FDG

U2 - 10.3390/molecules27092792

DO - 10.3390/molecules27092792

M3 - Journal article

C2 - 35566137

AN - SCOPUS:85129831693

VL - 27

JO - Molecules

JF - Molecules

SN - 1420-3049

IS - 9

M1 - 2792

ER -