Hello from JustAnswer.
There is no clinical evidence that Lazaprazole or any proton pump inhibitor increases the risk of developing psoriasis, by any mechanism. However, there is a theoretic risk of proton pump inhibitors that may play a role. The proton pump inhibitors are very strong inhibitors of acid release in the stomach. Theoretically, strong inhibition of the stomach acid may increase the risk of germs entering the body. Much of what is swallowed is not sterile, and the strong stomach acid is one of the mechanisms by which the body kills any germs that are swallowed. There are many other defense mechanisms, but stomach acid is clearly one of the mechanisms.
When proton pump inhibitors were first approved, there was so much concern about long term suppression of stomach acid that the original recommendations was that they should only be used for 4 weeks to get control of the condition being treated, and then either stop the medicine or change to another medicine that is not as strong, such as Zantac/ranitidine. As we gained more experience with the drug, it has become apparent that the theoretic risk did not yield significant clinical risk. And some people have more severe disease that got worse whenever we changed to a lesser medicine, so some people were kept on proton pump inhibitors long-term. Following these patients over years have shown only limited risks of infection associated with the proton pump inhibitors. It is not that the medicines adversely affect the immune system, but rather by affecting another mechanism that protects the body from entry of germs.
Psoriasis is a condition that can have many factors that can contribute to the illness in various people, and infection is one of the mechanisms that may be a factor. Most of the infections that are associated with psoriasis involve skin germs, so would be unrelated to stomach acid suppression, but there are some systemic infections that may have a role. So, even though there is no direct clinical evidence that proton pump inhibitors will increase the risk of developing psoriasis, there is a theoretic mechanisms by which it could do so.
The only way to know whether it is having this effect in you would be to stop the drug and see if there is any improvement in the psoriasis. If your stomach and hernia can tolerate being on no medicines, then that may answer the question more quickly. But if you have some recurrent symptoms, it would be better to use a different medicine, such as the Zantac/ranitidine to see if it will control the GI symptoms.
If I can provide any additional information, please let me know.