*3.2. IgY Treatment-Induced Changes in Experimental Murine Model of Psoriatic Dermatitis*

For naturally remitted Ps group, the mice were allowed to heal naturally and erythema, thickening and skin scaling were daily observed in order to appreciate the day when the effects produced by applying of IMQ-based cream disappeared. The mice were weighed at the beginning of the experiment (day 1), after IMQ-based cream treatment (day 7) and before sacrifice—day 22—when the natural remission of the IMQ-skin effects was noticed.

For IgY-treated Ps group, mice received a dose of IgY by gavage for 5 consecutive days, The evolution of the three in vivo parameters (erythema, thickening and skin scaling) was monitored and we established that the skin healing took place in day 20, 2 days earlier than naturally remitted Ps group. The body weight was recorded at the beginning of the experiment (day 1), day 7 (beginning of IgY treatment), at the end of IgY treatment (day 12) and before sacrifice—day 20—when it was macroscopically appreciated that the IMQ-skin effects disappeared.

Body weight (Figure 2a,b) revealed a decrease after the IMQ topical application (day 7) for both IgY-treated Ps group and naturally remitted Ps group. For the IgY-treated Ps group (Figure 2a) the values decrease until the end of the IgY treatment and at the end of the experiment, for both experimental groups, weight increases were recorded.

**Figure 2.** Evolution of the body weight (**a**) Evolution of the body weight for IgY-treated Ps group (*n* = 12)-day 1 (21.33 ± 2.14), day 7 (20.74 ± 2.24), day 12 (20.66 ± 2.27), day 20 (21.65 ± 2.28) (**b**) Evolution of the body weight for naturally remitted Ps group (*n* = 8)-day 1 (17.87 ± 0.81), day 7 (16.93 ± 0.78), day 22 (19.13 ± 0.21). The results are presented as mean ± SD; *n* = number of mice; D = day.

In order to assess the involvement of the triggered Ps on the secondary immune organs, splenomegaly evaluation was performed. Spleens were weighed separately and the ratio between spleen weight (SW) and body weight (BW) was calculated. Spleen weight was significantly higher in Ps group (0.22 ± 0.02, *p* = 2.19 × 10−<sup>9</sup> ) as compared to controls (0.08 ± 0.01) (Figure 3e). The measurements also showed that in IMQ-mice, SW/BW ratio is almost 3 times higher than in healthy mice (0.011 ± 0.001 versus 0.0039 ± 0.0002, *p* = 2.21 × 10−<sup>8</sup> ) (Figure 3f).

The SW/BW parameter was evaluated also for IgY-treated group. As mentioned above, a marked splenomegaly was noticed in IMQ-based experimental model of psoriatic dermatitis, namely spleen weights and SW/BW were about three times higher for Ps group as compared to control group. In the IgY-treated group there is a clear reduction of the splenomegaly. Figure 3a–d presents the macroscopic images of spleens and Figure 3e shows the mean values of spleen weights for all experimental groups.

As a measure of splenomegaly, SW/BW ratio was calculated for all groups and IgYtreated Ps group and naturally remitted Ps group were compared to control and Ps groups (Figure 3f).

(**a**) (**b**) (**c**) (**d**)

**Figure 3.** *Cont*.

**Figure 3.** Representative images for the assessment of splenomegaly reduction. Spleens harvested from (**a**) mouse from IgY – treated Ps group; (**b**) mouse naturally remitted Ps group; (**c**) mouse from control group; (**d**) mouse from Ps group; (**e**) The weight of the spleens for IgY – treated Ps group (*n* = 12) (0.09 ± 0.02) as compared to naturally remitted Ps group (*n* = 8) (0.08 ± 0.01), control group (*n* = 8) (0,08 ± 0.01) and Ps group (*n* = 8) (0.22 ± 0.02); (**f**) SW/BW ratio for IgY-treated Ps group (*n* = 12) (0.0040 ± 0.0009) as compared to naturally remitted Ps group (*n* = 8) (0.0044 ± 0.0003), control group (*n* = 8) (0.0040 ± 0.0009) and Ps group (*n* = 8) (0.011 ± 0.001). The results are presented as mean ± SD; *n* = number of mice).

At the end of the experiment, values for both spleen weight and SW/BW ratio after IgY treatment were identical or statistically equivalent to the values recorded for the control group Additionally, there are no statistically significant differences between IgY-treated Ps group and naturally remitted Ps group, for both spleen weight and SW/BW ratio. Thus, the splenomegaly observed after the induction of Ps (respectively, after applying the IMQ-based cream for 6 consecutive days) was completely remitted.
