An in vitro method for assessing the ability of an agent to prevent, treat and/or alleviate the symptoms associated with an inflammatory condition in an individual, said method comprising: (a) combining in vitro the agent with a reagent to obtain a parameter associated with at least one biological activity of USP15, wherein the at least one biological activity is a de-ubiquinating activity, wherein the reagent is • a nucleic acid molecule, wherein the nucleic acid molecule (i) comprises a promoter of a gene encoding USP15 and the parameter is a measure of the expression driven by the promoter, (ii) is a transcript encoding USP15 and the parameter is a measure of the amount of the transcript or (iii) is a transcript of at least one gene whose expression can be modified by USP15 and the parameter is the amount of the transcript; • a USP15 polypeptide; or • a binding partner of the USP15 polypeptide that can be de-ubiquinated by the USP 15 polypeptide; (b) measuring in vitro the parameter of step (a) to obtain a test level; (c) comparing the test level to a control level, wherein the control level is associated with the at least one biological activity of USP15 in the presence of a control agent known not to limit inflammation or prevent, treat, alleviate the symptoms of inflammation; and (d) characterizing the agent as (i) useful for the prevention, treatment and/or alleviation of the symptoms associated with the inflammatory condition when the at least one biological activity associated with the test level is lower than the at least one biological activity associated with the control level or (ii) lacking utility for the prevention, treatment and/or alleviation of the symptoms associated with the inflammatory condition when the at least one biological activity associated with the test level is equal to or higher than the at least one biological activity associated with the control level. (a) combining in vitro the agent with a reagent to obtain a parameter associated with at least one biological activity of USP15, wherein the at least one biological activity is a de-ubiquinating activity, wherein the reagent is • a nucleic acid molecule, wherein the nucleic acid molecule (i) comprises a promoter of a gene encoding USP15 and the parameter is a measure of the expression driven by the promoter, (ii) is a transcript encoding USP15 and the parameter is a measure of the amount of the transcript or (iii) is a transcript of at least one gene whose expression can be modified by USP15 and the parameter is the amount of the transcript; • a USP15 polypeptide; or • a binding partner of the USP15 polypeptide that can be de-ubiquinated by the USP 15 polypeptide; • a nucleic acid molecule, wherein the nucleic acid molecule (i) comprises a promoter of a gene encoding USP15 and the parameter is a measure of the expression driven by the promoter, (ii) is a transcript encoding USP15 and the parameter is a measure of the amount of the transcript or (iii) is a transcript of at least one gene whose expression can be modified by USP15 and the parameter is the amount of the transcript; • a USP15 polypeptide; or • a binding partner of the USP15 polypeptide that can be de-ubiquinated by the USP 15 polypeptide; (b) measuring in vitro the parameter of step (a) to obtain a test level; (c) comparing the test level to a control level, wherein the control level is associated with the at least one biological activity of USP15 in the presence of a control agent known not to limit inflammation or prevent, treat, alleviate the symptoms of inflammation; and (d) characterizing the agent as (i) useful for the prevention, treatment and/or alleviation of the symptoms associated with the inflammatory condition when the at least one biological activity associated with the test level is lower than the at least one biological activity associated with the control level or (ii) lacking utility for the prevention, treatment and/or alleviation of the symptoms associated with the inflammatory condition when the at least one biological activity associated with the test level is equal to or higher than the at least one biological activity associated with the control level.