Page 81 - Read Online

Sane et al. Microbiome Res Rep 2023;2:18 https://dx.doi.org/10.20517/mrr.2023.12 Page 5 of 12

Figure 1. Development of OA according to Lpps administration. Representative images of macroscopic degradation. (A) and of H&E-
stained joints; (B) of left knee (no injection), right MIA-injected joint from untreated and Lpps treated rat; (C) significant lower
prevalence of OA in Lpps treated group (Fisher’s exact test; P < 0.008); (D) rat discrimination by bacteria profiling according to OA
using PSL-R analysis. BC: treated rats; W: water-drinking rats; dark circle: OA rats; grey circle: healthy rats.

Rats responsive to Lpps treatment are clustered apart from the OA rats
PLS-R analysis of weight, APC numbers and bacterial counts data shows clustering by rat group according
to OA development [Figure 1D]. Plots corresponding to the two unresponsive Lpps rats are localized
between the water drinking group prone to OA development and the responsive Lpps group suggesting that
an optimal balance between the selected variables is associated with the protection.

Principal component analysis of the data from the whole group draws attention to two bacteria strongly
associated with the protective effect, i.e., Bacteroides thetaiotaomicron and the butyrate-producing
Eubacterium plexicaudatum [Figure 2]. Ligilactobacillus murinus in the distal ileum contributed to the Lpps
effect as well as Lactobacillus johnsonii localized in the caecum and colon. Additionally, Parabacteroides
goldsteinii colonizing the lower part of the digestive tract is associated with OA progression.

Moreover, PCA of data excluding the two unresponsive Lpps-treated rats linked as well
B. thetaoiotaomicron, E. plexicaudatum and P. goldsteinii to the regulation of OA onset. OA progression was
not related to weight. The number of APC (+) in bone marrow does not either contribute to OA onset.

A few bacteria are targeted by Lpps intake
To further investigate Lpps effect on the selected bacteria, counts were compared according to the diet and
OA development using ANOVA and Bonferroni post-hoc test [Table 1 and Supplementary Table 2]. In the
whole group (i.e., 10 control rats and 10 Lpps-treated rats), L. murinus and enterococci showed significant
expansion in the distal ileum of the Lpps-protected rats. On the contrary, rats developing OA exhibited
higher counts of Akkermansia sp. in the colon.